Abdulgader A. Sherif, B.Sc. (Cairo), D.I.C

STUDIES ON THE PERSISTENCE AND EFFECTS OF SOIL-APPLIED

CARBAMATE AND PHOSPHORUS INSECTICIDES ON SOIL FAUNA,

WITH SPECIAL REFERENCE TO THE COLLEMBOLA

A thesis submitted by

Abdulgader A. Sherif, B.Sc. (Cairo), D.I.C.

for the degreo of Doctor of Philosophy in the University of London

Imperial College of Science and Technology,

Field Station, Silwood Park,

Sunninghill, Ascot,

Berkshire. October, 1971. 2.

ADSTRACT

During the period 1960 -- 1971, field and

laboratory etudtes were made of the effects of two systemic insecticides, 'Zinophos and aldicarb on soil arthropods with particular reference to Collembola.

A comparison is made between the effects of these chemicals in arable, sandy and clay soil typos at Imperial College Field Station and Grassland Research

Institute.

Descriptions are given of te vertical and horizontal distributions of some soil inhabiting species and the variations of these distributions and recolonisation processes following chemical treatments.

Population changes in terms of numbers and species structure are considered with reference to-seasonal variation, chemical applications and toxic residues, and biological interactions between competing species.

The analysis of chemical effects is supported by evidence of species susceptibility from laboratory bio-assay species and chemical analysis of toxic residues in the soil at intervals after field applications. Factors affecting the persistence of toxic residues in the soil are discussed. J•-) •

TABLE OF CONTENTS

Title Page 1.

ABSTRACT 2.

TABLE OF CONTENTS 3.

GENERAL INTRODUCTION 7. SECTION 12. MATERIALS.. AND 1,,ETHODS 12.

Chemicals and Formulation 12. 1. Site and Design of Main Field Ex eriments 13. 2. Methods of Sampling and Extraction 17.

(a) Sampling. Tools 18.

(b) Modification to the sampler in 1969 22. (c) Extraction Techniques 23.

(i)Flotation Method 23.

(ii)'High Gradient' Method 25. 3. A general study of the soil fauna 34. 4. Horizontal Distribution 44. 5. Seasonal Distribution 50. 6. Vertical Distribution 50. 7. Faunal Group Relationship. 53. 8. Persistence of Aldicarb and fZinonhog in 57. Church Field Gandy soil 1968-1969 9. Persistence of. Aldicarb andiZinophos'in 60. Hurley, High Field (clay soil) in 1968-1969 10. Some effects of cultivation on the soil 63. fauna during 1969 4.

SECTION IT. 66.

THE EFFECT OF ALDICARB AND "ZINOPHOS'ON SOIL 66. FAUNA IN TWO SOIL TYPES, SANDY AND CLAY SOIL AT CHURCH FIELD AND HIGH FIELD 1969-1970 1. Methods and experimental design 67. 2. Results 69 (a) Lower. Church Field, Silwood Park 69. (i) COLLEMi3OLA 74. (ii) ACARINA 84. (b) Higli Field Hurley 92. (i) COLLEIIBOLA 95. (ii) ACARINA 99. 3. Comparative effecizof sandy and clay soil .105. on the persistence otl_11.4caxb and-Zinophos in relation to aagt4444 fauna of 0-6" soil profile 4. Long-term effects of aldicarb andlinophos 108. on the soil fauna of Church Field 1969-70 5. Vertical distribution of subterranean 111. micro-arthropods 6. DISCUSSION 118. SECTION 128. THE SUSCEPTIBILITY OF COLLEMBOLA TO ALDICARB 128 7057ETNOPHOSI INSECTICIDES IN THE LABORATORY AND BIOASSAY OF INSECTICIDE RESIDUES IN TEE SOIL 1. Materials and Methods 129. (a) Culturing Methods 129. (b) Age determination in Collembola 136. (c) Containers 138. (d) Insecticides 139. 5

(e) Methods of Treatment 141. (1) Filter paper method 141. (ii) Soil treatment method 142. (f) Mortality determination 146. (g) Statistical treatments 147. 2. Results 147. 3. Discussion 166. SECTION IV. 172.

THE EFFECT OF ALDICAT1B ON SOIL FAUNA. IN SAIOY 172. SOIL AT . 19 70..

1. Materials and Methods 173. (a) Experimental Design and sampling: 173. (b) Chemical estimation of aldicarb from 175. --thesoilde- Ilineci b -LTe net112L1 (i) Soil sampling 175. (ii) Preparation of samples and 177. clean-up procedure (iii) Preparation and processing of 180. T.L.C. plates (iv) Calculations for the 181. quantities of residual insecticides in the soil

2. Results 182. (a) Chemical degradation 182. (b) Analysis of ponulations 182. (i) COLLEMBOLA 187. (ii) Major Predatory Acari 205. (iii) Other Acari 210. TA V.:re (iv) Other A,r441.0/Drods 215. 6.

3. EffeCt of cultvation on the lIntxpated 220. Dpinllation of Boil fauna

4. Factors affecting no.:?sistence of 222. aldicarb

5. oct of suoy the soil faun 224.

6. DISCUSSION 228. SECTION V. 235. GENERAL DISCUSSION 235. SUEHARY 244. ACIEVILITDGELOTOT S 253. REFERENCES 255. APPENDICES 269. 7.

GENERAL INTRODUCTION Some soil organisms such as Collembola, Euchytraeidae

and onvthworms are beneficial to the fertility and structure of soil.

Mills and Sinha (1971) emphasised the importance of

soil Collembola whentheystated that: "Collembola play an

important role in the breakdown or raw humus and in the

comminution of plant residues, particularly in forest soils

(Hale, 1967). They also aid drainage and aeration by eating

decayed roots, thereby leaving channels which contain much

organically rich fecal matter (Kevan, 1962). Collembola are

less abundant in cultivated soils than in the forest soils

(Kevan, 1962) and less important in aeration since

mechanical tillage is used to aerate and breakdown the soil.

The current trend in agriculture towards growing crops

without tillage, particularly in the United States and the

United Kingdom (Edwards, 1969), is likely to favor

multiplication of Collembola. Under such conditions

Collembola may play an important role in maintaining soil

fertility in agricultural soils".

A good deal of qualitative research has been done

upon the spatial and temporal distribution of different

groups of soil fauna, including the dominant species

within the faunal groups, and their biology with respect

to their environment. However, there is a need for

quantitative studies with reference to the change in

environment due to the application of soil - applied

pesticides, and meteorological factors also have to be

considered. The use of chemical insecticides is frequently attended

by unintentional side effects that may be harmful to bene- 8. ficial arthropods as well as to the target pest. However there is still much to be learned about the effect of pesticide residues on soil fauna. Edwards (1966) reported intensive studies on the fate of organochlorine insecticides in soils, these compounds have been extensively used against a wide variety of pest species. For example, dieldrin and BHC seed-dressings, were

±ound to have more potent effects on wireworms than aldrin seed-OresIng ech }j no d17,!'nct or ,-7.esidul effect

(Potter at al., 1968).

The undesirable side effects of the organochlorine compounds have been reported by many workers, Shoals, (1933) found that micro-arthropDcl:s were generally reduced in numbers by BHC applications. He also reported that after

DDT application the numbers Of Collembola greatly increased while the predatory and saprophagous mites decreased. Such effects were attributed to the reductions in numbers of predatory mites, particularly the Mesostigma. (Sheals, 1955,

1956; Edwards and Dennis, 1960; Edwards and Arnold, 1963,

196L-; Edwards, Dennis and Empson, 1967).

Little information was available on the fate of organophosphorus insecticides in soil, though it was generally accepted that they were less persistent.

Recently, the use of organophosphorus insecticides, rather than chlorinated hydrocarbons, has been encouraged, although it has been reported that some of the most important soil applied organophosphorus insecticides have shown possible undesirable side effects when the insecticide is placed locally at a very high concentration. 9.

Edwards (1965) and others, investigated the side-effects

of a number of organophosphorus insecticides including

parathion, diazinon, disulfoton, Vinophos, sumithion and

various experimental chemicals produced by Shell, Fisons

and Bayer. None of them affected soil animals to the/same tictent

of the organochlorine compounds. The Collembola was the

most sensitive group of animals to the organophosphoriks insecticides but larvae of Diptera and Coleoptera were less

susceptible to them than to the organochlorine compounds.

Scopes (1965) also showed that band treatments of ilnophos'had drastic effects on Collembola and mites. Even

at 10 ppm. the insecticide due to its persistence kept

numbers below those of untreated plots for 24 months.

Edwards et. al. (1967), tested 4 organophosphorus

insecticides, namely parathion, diazinon, phorate and

disulfoton on soil fauna and found that the surface-dwelling

and the deeper-living Collembola were affected. These

chemicals also affected Mesostigmata, Prostigmata and

oribatid mites. Numbers of some groups were reduced but

not to the same extent as by organochlorine treatments

and some groups of Collembola, Prostigmata and oribatid

Mites increased to populations far greater than those in

untreated plots. The increases were attributed to the

destruction of predators, particularly the gamasid mites.

The effect of pesticide residues on soil fauna has

been extensively studied by Edwards (1966, and 1969) and by Voronova (1968). A recent review (Butcher et..al., 1971)

briefly covers some recent advances in this field. It was

suggested that microbiollgical degradation is an important

factor affecting the persistence of carbamates in soil

(Abdellatif et. al., 1967). 10.

Pain and Skrentny (1969), investigating the residues of A Zinophos found it to be present in detectable quantities up to 100 days after the time of application.

Some carbamates are effective against a wide range of pests and pathogens, one of these carbamates is aldicarb which could be widely used in future as soil - applied systemic insecticide as well as nematicide (1eiden et al., 1965).

Bull (1968) reported that aldicarb is not persistent in soils because of its rapid degradation to less toxic oxime derivatives of carbamates. The extensive usefulness of the compound is uncertain due to the hazards associated with its application, however, an investigation into any possible undesirable side effects on soil fauna was considered necessary.

The persistence and long-term effect of carbamates and organophosphorus insecticides have not been fully investigated. Therefore the present work was carried out to determine possible harmful side effects in relation to persistence of a newly developed carbamate insecticide (aldicarb) compared with the physiologically non-selective organophosphorus systemic insecticide thionazin (zinophos2). Oh11'0- Prt l 0 n The granular fnformatian hai" already been described by

Edwards (1966) as being the most efficient with regard to persistence in soil application Persistence of pesticides varies according to the type of soil (Edwards, 1964; Skrentny, 1970). Edwards (1970) stated that rain-fall and cultivation both affect the persistence of pesticides. Getzin and Rosefield (1966) 14 4 studied the persistence of C labelled Zinorhos up to 24 weeks 11. in four types of soil, and found that the type of soil had a definite effect on the persistence of the insecticides.

Fortunately Skrentny (1970) has recently studied the fate of aldicarb in the two different types of soil included in these studies and found different rates of degradation of pesticide detected by thin layer c llromotography (TLC) up to

12 months after application, Springtails and mites were known for their sensitivity to soil pesticides Edwards (1965).

It was, therefore, considered interesting to study these micro-arthropods from insecticide treated fields in two different types of agricultural soils at Imperial College

Field Station and the Grassland Research Institute, Hurley, in order to analyse their std':' effects on the populations and activity of Collembola, Acari and other arthropods. Seasonal changes in the number of the fauna and their distribution in the soil, as affected by chemical residues, are also

considered. 12.

SECTION 1.

MATERIALS AND METHODS

Laboratory techniques specific to particular experiments will be discussed in the main text.

Chemicals and Formulation

The following granular systemic insecticides were used in field experiments:-

, (a) Aldicarb C7H14N202S - known as LT Teinik 105, UC7211491 2-Methy1-2-(methylthio) propionaldehyde 0-(Methylcarbamoyl) oxime _7, developed by the Union Carbide Corporation U.S.A. as a new class of oxime carbamate insecticide, because of the high hazards, the granules were used 10% a.i. on corn cob base, 16/30 mesh, quick release coating.

(b) Thionazin C8II13N203PS - known as diethyl 0-2-pyrazinyl phosphorothioate 7; 10% active ingredient on attapulgite clay. This pesticide is known also as 'Nemafos', 'Unophos'. The size of the, granules was between 20-60 mesh/inch.

The name 'Zinophool has been used in the following text. 13.

1. Site and Design of Main Field Experiments

Two field experiments were set up in 1968 to study

the persistence and long-term effects of the two systemic

soil applied insecticides aldicarb and'Zinophos The

experiments were laid do,:Tn in Church Field, Silwood Park

and in High Field, Grassland Research Institutes, Hurley,

Berks. The soil characteristics of the two sites were

dissimilar (Tablet ).

Table: 1

Soil Characteristics*

Site ; Field ! Bulk % 1 pH 4 Mechanical analyses 1 ; capacity !density . Organic'1 i------r-- --. i matter Silt! Clay Fine!Course sandy sand

Church Field I 19.8 1.38 2.4 5.4 115.31 5.1 49.3 29.5 1

High Field ! 22.3 j 1.29 2.2 7.3 12.4;24.7 27.9 32.9

From Pain and Skrentny * J.Sci. Fd. Agric., 1969, Vo. 20.

Pain and Skrentny (1967) reported that the acid soil

of Church Field provided more favourable long-term persistence

and systemic efficiency of itinophosi than in the clay

alkaline soil of High Field.

The experimental areas were ploughed, rotivated and

then divided into two parallel blocks, (Figs.1, 2)

each block consisted of three plots of 12 x 12 yards.

SITE I FOOTPATH

ro F11 0 0 A NOPHOS. CONTROL ALDICARB 36' N . 0

1-1

P. CD B CONTROL ALDICARB Zl NO PROS.

0 c÷

Potato Slope Rows 1St'

6 OL I I 1

cpcopiptv I 0 .11, U 0 D AoLidou!z , 9

ado's ts. lo p ld ie

10J1U0 D ,soydoutz, q .1 D p up pv V h F SMOG Hig 01 D 1 0 d cs < T I S 109 .9E IC ri.r-I

Z 3119 16.

Headlands 3 feet wide separated each plot and block while

the whole experimental area was bordered by 6 feet wide

bands of fallow soil. The experiment was laid down as a

omised block and there were two plots each of alidcarb and iEinophos plus two untreated plots as controls at each

site. The orientation and the slere of these plots have

been shown in Figs. 1, 2.

Since the distance between Church Field and High Field is less than 20 miles (32 km) climate would not seem to

be the major factor influencing the difference in persistence

of the insecticides. Details for each site of the 1968

experiment are as follows:-

Church Field: The plots marked out on 18th March, 1968

had application of fertilisers on 19th March at the

following rates:-

I.C.I. No. 3, 6 cwt./acre equal to 20.21 lb./plot

I.C.C. No. 4, 6 cwt./acre equal to 20.21 lb./plot

Kieserite (Mg SO2) at 5 cwt./acre equal to 16.8 lb./plot

Herbicide (Gammaxane w) was applied. The plots

were planted with a variety of potato, Penland Dell, in

late April 1968 in 12 rows per plot and 24 potatoes per row.

On 30th Aprillinophos'was applied to the appropriate

plots - broadcast on the surface with Suttons spreader at 3.34 sq. 4.4 • approx. 38 grins. per 4 gq, y4. i.e., 10 lbs active ingredient/acre equal to 100 lbs. 10% granular, and

aldicarb was applied to the appropriate plots at the same

rate on 3rd May. 17.

High Field: The potatoes were planted on the 8th April

and the plots marked out at the end of April. 'Zinophos'

was applied on 2nd May to the appropriate plots and on

14th May aldicarb was similarly applied.

During the first few months the land was regularly

hoed to keep the weeds under control but later in the

experiment the natural flora was allowed to grow. The

weed growth developed a grass sward in some parts of the plots.

The purpose of these experiments was mainly to

study the persistence of insecticides and their effect

upon the soil fauna.

2 Methods of Sampling and Extraction

It was planned that soil samples would be taken regularly

from April 1968 to November 1970, but because some materials

of the high gradient extraction apparatus were not available

commercially, the first soil samples after the treatment

could not be taken until July 1968. The actual occasions

of sampling are evident from the data tables.

It was required to estimate variations in numbers of

Collembola vertically and horizontally in addition to the

total number of fauna present, because it is well known

that Collembola tend to form aggregations, and there is

little doubt that Collembola are normally more abundant in 18.

the upper layers of soil. Thus each sample was divided into

three layers, i.e. depths 0-3, 3-6 and 6-9 inches, giving a

total of 72 soil cores from Church Field on each occasion.

At High Field only two layers were sampled because the

soil was rather more stony and had a high clay content. Thus

each sampling rendered 48 Goil cores.

Sample units which were mainly occupied by large stones

or potato tubers were discarded where possible and another

sample taken from an adjacent unit, but occasionally such

undesirable samples reached the extraction stage accidentally

(the stones or tubers being totally obscured by the surround-

ing soil) and this was one of the factors causing surprisingly

poor yields from some samples.

Each plot was divided, on a chart, into four sub-plots

and these in turn were divided each into four smaller plots,

which were again sub-divided into nine units numbered 1-9

each measuring one square yard (Fig, 3 ).

On each sampling occasion four random samples were

taken from each plot ensuring whilst so doing that each sub-

plot provided one sample. As it was planned to take samples

on nine occasions during the experiment the re-division of

each sub-plot into smaller plots and units ensured that

random selections could be planner: and arranged to avoid

any unit being sampled more than once. The exact place to

bore was measured out on the plot using a square yard metal-

lic frame and co-ordinates chosen using tables of random

numbers. (a) Sampling Tools A sampler was designed, in 1963, to take Bakelite rings,

and was a modification of the one described by Macfadyen (1961)

1 9 .

MMEN■

IS) • n v -

. h) * .0 a) us 0' ....1

10• 1:0 I 10 > 10 4 1 . —

—. —. — r —

W 1 to

1 , .

(a)

Aim

Fig.. 3. Sampling chart. 20.

Fig.4. Sampling tool. 21.

(Fig. 4 ). The graduated cylindrical sampling tool illustrated was 2 feet long with internal diameter of 2" and made of hard steel and contained the rings of Bakelite laminate held by means of a removeable bar, which pas sed through holes bored through the cylinder 3" apart. The cutting edge was' case-hardened on the inside so that wear was negligible and, the cutting edge of the core:? was always kept sharp.

Ph 'diameter of the sampling tool was chosen so that it would provide a sliding fit for the Bakelite rings. A half- inch slot ran the length of the cylinder, starting just below the, handle and terminating about 141c” from the cutting edge.

This 'cut-away' enabled the Bakelite rings to be removed easily by inserting a piece of wood or a spatula, and lifting theM to the top.

The stout handles were made of iron, one inch in diameter, and'covered. with rubber.

7n use the operator stands with the sampler in his hands, and by exertion of pressure combined with rotation sinks the sampler to the.. desired level.. After, withdra-,Iral of the sampler from the soil the Bakelite rings holding the soil samples are pushed out gently with the help of a rod through the lengthwise slot in the sampler, and trimmed with a simple cutting tool.

Difficulties were encountered in sampling the dry

powdery soil in summer, and it was advisable to irrigate

the areas and allow the moisture to penetrate at leas' to

the lowest depth to be sampled. In the case of very dry

soil, in summer, samples were taken from the first two .,! w 4a. The sleeve. 22.

levels and removed from the auger after which other empty

Bakelite rings were inserted and the sampler was sunk into

the third level through the same hole.

The latter practice described above caused some mis-

givings on few occasions, as it was thought that on withdrawal

of the auger from the first two levels some fauna remsining

around the periphery were at times falling to the base of the

hole and consequently being included in the third layer

specimens. No doubt some fauna became agitated by the

disturbance and fell to the base with small particles of soil

onto which they had jumped in their confusion. Proof of

this accidental fall was obtained upon discovery of several

surface layer fauna in the third layer samples which were

conspicuously absent from the second layer.

The average weight of air-dried samples was approxi-

mately 325 grams, with a range from 276 to 454 grams, the

volume of the samples was about 241.cc; (2.5"diameter x3" in depth).

(b) Modification to the sampler in 1969

A plastic sleeve of internal diameter 2;-? and external

diamter 25/8", 15" in length, was placed inside the sampler and had holes to correspond with those in the

sampler, (Fig. 411). By the use of two sleeves, it is

possible for an assistant to transfer the soil samples to

containers while the auger was re-employed on the next

sample point. Another advantage cf using a sleeve is that the sample

from each depth is of the same density. It was noticed

when taking samples without the use of the sleeve that the 23,

soil from the lower levels was at times too highly compressed

due to the pressure exerted upon it by the soil above. Also,

when the Bakelite rings were modified (as described later),

it was found that the internal diameter of the sleeve being

.similar to that of the rings ensured that the plugs of soil

issuing from the sleeve fitted snugly into the Bakelite rings

of the containers.

The introduction of the sleeve has proved so successful

that from January 1969 it was possible to take samples from

the fourth level (i.e. 9-12").

Attempts had previously been made to take these fourth

level samples using only the Bakelite rings but, in addition

to the problems of compression already mentioned, it was

found that in particularly moist conditions the base of the

fourth layer was of insufficient solidarity for retraction

and fell from the auger before it could be removed. This

'accident' is precluded when using the sleeve because in

such conditions the auger is sunk into the soil a few inches

more than necessary and thus the top 12" can be extracted

intact. A wooden plunger of slightly less diameter than

the internal diameter of the sleeve was used to expel the

soil core from the sleeve.

(i) Flotation Method Although mechanical methods for the extraction of coil

animals vary considerably in technique, they all owe their

origin in principle to the flotation method. Flotation methods collected .with hand sorting of the material( enable separation of small 24.

animals from mineral soils and are based on the principle

that organic materials float in solutions of a specific gravity

of 1.2 whereas mineral matter sinks. A simple flotation

method with hand sorting of the floating organic materials

is here described.

The usual procedure was to gently crumble the soil by

hand. Stones and any other 'alien' objects were removed

and about 15 to 20 grams of soil were placed in a plastic,

dish containing magnesium sulphate or sodium chloride

solution (sp. gr. ca. 1.2). This was stirred and left for

a while. The animals floated to the surface. Some were living specimens of certain Collembola and a few were .Acari.

A small portion of the suspension was withdrawn and examined.

The main problems arising in this simple flotation

method were as follows:

(1) The need' to disperse the soil particles in order

to allow the Collembola to rise to the surface. Damage may

be caused to a specimen by excessive stirring or it might

become submerged.

(2) The requirement for a suitably coloured background.

The colour chosen depends on the colour of the particular

animal group under examination, and thus for optimal

conditions would need to be varied according to the particular

animals under study.

(5). Sorting samples by hand was extremely tedious and

time consuming, and thus errors could be expected when

counting a large number of samples of unit size in the short

time available for each one. 25.

It was felt that this technique must involve dis-

advantages such as rough handling and difficulties in

separating the small arthropods from organic matter -

especially where plants were mixed with the animals.

(ii) 'High Gradient' Method

During the present work the high gradient cylinder

was chosen for the routine extraction of 120 sample units.

To date this is the most efficient dynamic apparatus, being

ten times more efficient for Collembola extraction than

the ordinary Tullgren funnel(Macfadyen, 1961).

The high gradient method depends on a vertical tempera-

ture gradient in the soil core which acts in two ways:-

(a) The higher temperature on the upper surface

forces animals to escape to the lower cooler levels of

the core.

(b) The coil gradually dries out, progressively from

the top surface, again forcing the animals to move down

through the core.

As the temperature is increased and dries out more

completely the animals leave the core at the base and are

collected in suitable containers.

The methods of collecting the samples, transporting

them to the laboratory and their treatment in the extraction

apparatus in 1968 and subsequent modifications of the are techniques/as described below.

The Bakelite rings were pushed out of the corer and

were separated from one another and from the unwanted plug

of soil in the lower end of the corer by the use of cutting

device. A small square of aluminium sheet, sharpened along 26. one edge and with the opposite edge folded to afford a good grip, proved most suitable for this purpose.

The Bakelito rings, of 2im internal diameter, were suitably tuperod to fit into a motnllic circlet frwma.which held in place a gauze disc or sieve plate. This plate rested on the small inside edge of the circlet frame and provided a mesh area covering exactly the open end of an aluminium canister of nominal diameter 23/8m and length 3" (Fig. 5 ).The sieve apertures were of 13 mesh per linear inch and the wire was of aluminium.

In some of the preliminary samples extracted a considerable amount of fungus sealed the holes of the mesh.

It was found necessary to dip the sieves in a 0.2% solution of the fungicide Nipagin (which contains Streptomycin and Terramycin) before use.

A lid of 24" internal diameter covered. the other open end of the Bakelite ring so that the sample was sealed in order to minimise loss of specimens from field to laboratory. Unfortunately it was not possible to attach the canister to the ring assembly in the field for reasons explained elsewhere. Thus the samples were gathered in small batches, sieve side uppermost, and transported to the laboratory. The retaining caps were removed and the cylinders were placed, sieve downwards, over the canisters already in situ in the wooden rack of the extractor (Fig.6., 6a.).

These canisters contained either 5 ml. of distilled water in order to sustain the life of the fauna or a saturated aqueous solution of picric acid which has been used as 2?.

Fig.5. Bakelite ring and aluminium canister. 23.

Fig.6., 6a. High gradient extractor. 29. procorvutivo fa-utd (providei that the inside of the aluminium canister has been varnished with Shellac frequc.ntly)(Call 1968).

The Macfadyen high gradient extractor (Macfayden 1961) was used (Fig. 6 ). The apparatus had 120 port positions for cylinders and canisters.

The cores in the apparatus were kept at room temperature for 24 hours. The temperature was then gradually raised from room temperature (ayoroximately 20°C.) to 45°C. over the next eleven days of the twelve days extraction period.

Heal- was provided by heating elements placed two inches above the top of the 3" cylinders. A steep temperature gradient was ensured by placing th4Canisters in a water bath of circulating cold water. The water maintained a relative humidity of 95% in the apparatus when the sides were in place (Fig. 6a). After 12 days extraction each canister was removed from the apparatus and the animals transferred • Tor— alcohol of 70% plus 5% glycerine into a 3" x 1" specimen tubes. These test tubes were stored until identification and counting were carried out. The extracted animals were transferred into a Petri dish of about 5 cm. in diameter and under a dissecting microscope of x magnification, Collembola and other arthropods were counted.

Collembola were identified under a dissecting microscope of

x 50 magnification without mounting when possible. Other Collembola or Acari were cleared and mounted in

polyvinyl lactophenol(Goto, 1964), and identified under

the microscope of 40 - 100 magnification, and sorted 30, 36n440 according to Order, Frunilykrid species. Some species were identified 'ay specialists.

Collembola which were required for culture were collected in water and then transferred to culture jars.

A list of identified arthropods is included in the appendix 11, 2, 4; 5. previous method has some of the following drawbacks.

(1) Some samples of the 3" cores were mainly occupied by large stones or potato tubers even though care was taken to discard these samples.

(2) Because of a slight discrepancy between the size of the metallic frame of the Bakelite ring and the diameter of the aluminium canister it was not possible to Wix the soil-bearing rings in the field and permitted the escape of an occasional specimen during collection and transportation of the samples.

(3) It was necessary to fit a metal circlet over the Bakelite ring in order to form a close fit with the canister. It is possible that one or two specimens were unable to fall into the canister by becoming trapped in the crevice caused by this circlet frame.

(4) When radiant heat was applied to the 3" cores it may have penetrated too quickly to allow all of the specimens to escape from it due to their difficulty in travelling the full 3" distance. This is borne out by comparison with similar treatment of 1-" cores which did not provide such a formidable obstacle to the specimens escape (see Table 2 ).

(5) It is possible that the use of the aluminium cutting device to separate the cores (as previously described) 31.

may have had the effect of sealing off some of the soil

pores, thug hnmpuring or provonting the escape of some

animals. This factor was eliminated in 1969 when the use

of the cutting device was discontinued upon introduction

of improved sampling. Before this attempts were made to

minimise this hazard by scratching the cut surface before

extraction.

(6) Although adequate for Collembola and Acari the sieve used was of small mesh and prevented the movement of larger species and there was no provision for their escape

through holes or gaps in the side of the rings due to the rings being equal in diameter to the containers.

The following modifications were made at the end of

1968 and used in subsequent sampling:

(1) It was decided to divide the 3" core into two cores each of 14". This had the effect of exposing many of the stones, tubers etc., which would otherwise have remained undetected, and also lessened the distance which the insect had to travel to escape from the radiant heat.

It was also found that this reduced the period of extraction from 12 days (for 3" cores) to 7 days for the 14" samples.

For 3" cores the high gradient method extracted only 67% of the total (based on the remainder extracted by the flotation method applied after high gradient extraction) and

88% for 1--A-" cores (Table 2

32,

Table: 2

Comparison of the efficiency of cores of different thickness for the extraction of T. krausbaueri from sandy soil by simple flotation and high gradient cylinder methods. fieptembert_1968

7-- -7- Thickness Depth ',High Mean of 4 Flotation, Efficiency of core in gradient samples of high inch Flotation gradient after high method gradient

1.5" 0-1.5 I 55 13 83

1.5-3.0 71 13 78 3.o-4.5 l 48 2 52 4.5-0.o j 39 0 41 Total 213 28 1 254 Y 21300/208$%

3" 0-3.0 134 71 131 3.0-6.0 48 20 6o

Total 182 91 191 i18200/275 67%

This increase in efficiency is due to a very steep

gradient build-up of temperature over the 1.5" soil sample

in comparison to the core of 3". The flotation method was more efficient than the high gradient method but the latter

is more convenient when handling the large number of samples

required in these studies.

(2) The aluminium canisters were fitted with a screw-

on circlet top (the original lid with the centre removed)

which held in position the sieve of wire mesh. The

internal diameter of the Bakelite ring (2i") was increased

at one end by about one sixteenth of an inch to permit the 33. entry of the canister/sieve assembly to a depth of approx- 1 imately /8,as soon as the sample-bearing ring was removed from the corer (or, latterly, as soon as the ring had been filled from the sleeve) ( 22 ). The other end of the

Bakelite ring, of course, being capped immediately.

(3) A trailer was constructed with removeable racks with compartments numbered 1-120, into which the samples were placed with the seive uppermost (Fig. 7 ). In this way samples could be transported from plot to laboratory, even over the most bumpy ground and without undue haste, ensuring that no specimens were lost and a cle74n extraction obtained. In the case of samples from High Field, Hurley, it was necessary to place the samples similarly into wooden racks mounted in the rear of a motor transport vehicle.

Other methods specific to particular experiments are contained in the relevant sections.

Fig. 7. Trailer and sampler with a sleeve. 34.

7 A General study of the soil fauna

To study the behaviour of different soil animals

with respect to space, time and in relation to each other,

the common species (Appendix 1, 2, 3, 4, 5) have been considered

in three groups, namely:-

(1) Colleli,bola

(2) Acari

(3) Other arthropods

At present only a group study has been made and on

the completion of sampling similar treatment will be

given to dominant species within each group, and a study

of their relationships to one another. Tables 3, & 5

show the mean distributions of Collembola, Acari and

other arthropods obtained from the sandy soil of Church

Field in the control, 'Einophos and aldicarb plots, by

the high gradient extraction method.

The population of each group in the treated plots

were compare with the respective totals extracted from the

top 9" of the control plots (Table 6). Since the fauna

extracted from the cores were pooled on each sampling

occasion it is not possible to calculate standard errors

for mean densities.

The method of sampling is not adequate for certain

zrouPs of the larger invertebrates such as earthworms

and carabid larvae and these groups are discussed only to

indicate trends in their response to the pesticide

treatments. 35. Table: 3

Spatial & temporal distribution of Collembola per 14.73 cubic in (241.cc) of soil in Church Field during the summer quarter of 1968. (Percentage of Control)

Soil Depth 0 - 3 in. 3 - 6 in. 6 - 9 in. 0 - 9 in.

Treatment Z A Z A Z A Z A

Date of Sample 1st July - 7.4 4.o 0 1.8 0 0 3.9 2.9 14th July 32.1 21.6 36.4 13.3 11.8 8.8 31.2 17.9 13th August 36.7 38.7 50.2 29.1 42.3 24.5 41.1 26.6 3rd September 45.0 60.2 60.2 70.6 65.4 82.3 67.9 62.6 3rd October 44.9 105.5 48.6 130.0 38.7 96.3 44.7 109.2

Z = Soil treated with'Zinophosl A = Soil treated with Aldicarb 36.

Table: 4

Distribution of Acari per 14.73 cubic in. of soil in Church Field (1968) (Percentage of control)

Soil Depth 0 - 3 in. 3 - 6 in. 6 - 9 in. 0 - 9 in.

Treatment Z A Z A Z A Z A

Date of sample 1 1st July 23.8 42.9 28.3 30.2 11.1 0 22.9 29.2 14th July 67.4 9.3 92.6 14.8 4.7 11.6 67.? 11.5 13th August 52.8 79.2 93.1 44.8 73.1 48.1 74.1 57.4 3rd September 81.1 73.7 83.3 79.8 91.4 60.0 84.3 72.3 3rd October 91.7 61.5 85.0 69.4 113.8 71.3 94.2 66.4 37. Table: 5

Distribution of other arthropods, per 14.73 cubic in of soil in Church Field (1968) (Percentage of control)

Soil Depth 0 - 3 in. 3 - 6 in. 6 - -9in. 0 - 9 in.

Treatment Z A Z A Z A Z A

Date of Sample 1st July 23.3 20.0 51.6 24.2 0 0 1.6..7 20.8 14th July 33.3 21.1 28.0 60.0 25.0 20.1 31.4 31.4 13th August 24.1 27.8 73.3 57.8 53.8 28.2 47.8 37.0 3rd September 55.8 69.2 75.0 70.8 70.5 59.1 64.6 67.7 3rd October 97.1 157,2 23.7 130.0 25.4 49.2 70.3 133.6 38.

Table: 6 mean The /number and percentai7es contributions of Collembola, Acari and other arthropods to the total arthropods populations in the top 9" of soil in contra..plots Church FieldcI9-6-8.) ( Numbers per 1 4.73.cu inches)

Mean 1 July 14 July 13 Aug. 3 Sept. 3 Oct. density No. % No. % No. % No. No. control

Collem bola 10.3 59 23.4 60 31.6 76 38.2 72 58.4 69

Acari 4.8 27 12.2 31 5.4 13 8.3 16 13.7 16

Other Arthro- pods 2.4 14 3.5 9 4.6 11 6.5 12 12.8 15

Total 17.5 100 39.1 100. 41.6 100 53.0 100 84.9 100 -4 ■■•

Quite clearly Collembola are the dominant group of

fauna, and hence can be used to indicate the spatial and

temporal distribution of the soil fauna in the control

plots. The effects of the systemic insecticides used on

the animals as a whole will be discussed later.

The distributions of the three groups of fauna in

the clay soil of High Field, Hurley is presented in

Tables 7, 8, 9. A comparison of the population densities of the three

groups of fauna is shown in Table 10.

Generally speaking, the density in the sandy soil

is about 1.77 of that in the clay soil. Some workers for

example Murphy (1955) and Klima (1956)have considered

micro-arthropods in relation to soil structure, and have 39.

Table: 7

Distribution of Collembola per 14.73 cubic in., of clay soil in High Field Hurley (1968) (Percentage of Control)

Soil Depth 0 - 3 in, 3 - 6 in. 0 - 6 in.

Treatment. ' ' Z A .Z A Z A Date or sample 12th July 44.8 12.5 33.0 0 , 41.2 8.8 15th August 44.8 22.0 58.$ 33.3 49.4 25.6 4 4th September 32.3 40.3 39.1 43.7 34.9 41.4 5th October 94.3 74.4 85.7 42.7 90.7 58.7 4o,

Table: 8

Distribution of Acari per 14.73 cubic in. of clay soil in High Field Hurley. (Percentage of Control) ,

1- Soil Depth . 0 - 3 in. 3 - 6 in. 0 - 6in.

Tratment Z A Z - A Z A . • Date of sample 12th July 80.8 52.1 22.5 - 67.4 60.2 33.6 15th August 85.0 76.7 67.4 40.9 76.2 57.9 l 4th September 49.6 42.9 56.3 49.1 53.0 46.1 5th October 62.7 115.7 92.8 58.8 77.8 87.9 1 41.

Table: 9

Distribution of other arthropods per 14.73 cubic in. of clay soil in High Field Hurley (1968) extracted by dynamic method (Percentage of Control)

:Soil Depth 0 - 3 in. 3 - 6 in. 0 - 6 in.

Treatment. Z A Z A Z A Date of sample 12th July 89.7 86.2 90.9 0 90.0 60.0 15th August 42.3 32.7 33.3 66.7 39.0 43.9. 4th September 38.2 38.2 38.0 48.0 38.1 41.3 5th October 145.8 137.5 62,0 54.3 98.8 93.9 42.

Table: 10

Comparison of mean ponulation densities of different groups of soil fauna types of untreated soil (0-6" depth)

Sandy loam (0-6") . Clay (o-6”)

Date of sample C AC AR Total C AC AR Total

14th July 15.9 8.1 2.1 26.1 12th July 8.5 5.7 1.0 15.2

13th August 15.7 2.8 2.5 25.0 15th August 8.4 6.3 2.1 16.8

3rd September 23.0 4.5 3.8 31.3 4th September 12.5 5.8 3.1 21.4

3rd October 35.2 7.9 8.0 51,1 5th October 13.0 4.9 4.1 22.0

SUM 93.8. 23.2 16.7 133.4 42.4 22.7 10.3 75.4

MEAN 23.5 5.8 4.1 33.4 10.6 5,8 2.6 18.85

Sandy Loam ± clay 2.21 1.03 1.61 1.77

C = Collembola AC = Acari AR = Other Arthropods 43. shown that: tho highest densitio& occur where the pore spaces are largest. According to Tia.lrl/v (1955) the cavity size decreases with depth in mineral soils, and here again the results show high densities of animals in the upper layers of soil. Generally the total porosity of clay soil is higher than sandy soil except where colloidal clay percentage is very high.

One may point out that the necessity of high non- capillary porosity is not only for free movement of fauna but also for the circulation of free air. It is a well known fact that the exchange of gases between the soil and the atmosphere does not take place efficiently in clay soil, leading to the accumulation of carbon dioxide in the soil and making the environment unfavourable for the fauna. The clay soil from the plots examined contained a high percentage of stones, many of considerable size, which might have a relative effect on the soil porosity. The presence of these stones also made pene- tration of the soil rather difficult, hindering and rather limiting sampling with the soil corer. 44.

4. Horizontal Distribution

Many authors have reported tendencies of micro-arthropods

to aggregate (Glasgow, 1939; Macf adyen 1952, 1957; Raw 1956;

Hughes, 1962; HaarlOv, 1960; Poole, 1961; Usher, 1970)

Hughes proposed a new technique for studying aggregated

populations by comparing the probabilities of sampling with-

in an aggregate and of the "tie-line". It was therefore,

considered necessary to make statistical comparisons of

population densities of the more abundant Collembol and

Acarina to understand some of the critical fluctuations in

order to reveal possibilities of biological and physical

interactions.

Intensive random sampling was carried out by extracting

the major soil fauna from 0-3" cores obtained from the control

plot in Church Field. Data obtained were punched onto cards

and analysed on the University of London CDC6600 using a

programm developed by Reyna (1968). Statistical comparisons

were made for the following distributions; (1) Normal,

(2) Poisson, (3) Double-Poisson, (4) Trunctated Poisson,

(5) Neyman A, (6) Trunctated Neyman A, (7) Binomial (8) Negative binomial, (9) Trunctated negative binomial and, (10) Logarithmic. The results are summarised in Table1lal b

The coefficient of dispersion between sample densities

is in all cases greater than unity and indicates that the

distribution is spatially underdispersed. Most useful fits

were obtained for the Neyman type A and Negative binomial

distributions. A population consisting of randomly located

individuals would show a distribution of the Poisson form

with variance equal to the mean but the Poisson did not fit

any of the distribution data. 45.

Table:11 (a)

Comparative results of two applied distribution for eight species of Collembola and three species of Acari from untrerited lower Church Field

Species No. of Neyman type A. Negative Binomial 2 sample X2 D.F Probability X D.F Probability Collembola 0. trinotatus 60 21.0 5 P. 001 88:8 5 . . 2>P>. 1 T. karausbaueri 60 - - - 13.6 19 ' .9.>1)„>.8 L. :47.,saleus 60 27.9 5 P<.001 4.7 5 .5,EN.3 F. (4.11adrioculata* 120 2.1 2 .57P7.3 14.2 1 BC-.002 F. candida 60 11.8 2 .01>Q01 1.5 - 2 .5>1),-.3 I. Productus* 120 1.1 2 • .77P7.5 1.g 2 .57P?.3 I. thermphila 60 10.6 2 .0T7P>.001 4.5 3 .3›1›..2 I. viridis* 120 32.8 6 P‘0.001 1.6 4 .97.0....8' Acari

P. brassipes 60 6.1 5 .3)P>.2 5.4 6 .57P)..3 P. Punctum 60 14.5 5 .02>pp..01 9.7 4 .05>P7.02 Pygmephorus sp. 60 4.3 4 .5>P7.3 6.6 5 0.3>ip>,.2

* Number of individuals were not sufficient therefore more samples were taken. 46.

Table:11 (b)

Mean number, variance, variance/mean. and k values for goodness fit of negative Binomial distribution*

. . Species Mean Variance variance/mean k

Collembola 0. trinotatus 5.1 58.2 11.3 0.60 T. krausbaueri 91.6 4772.0 5.2 1.51 L. cyaneus 6.4 92.7 14.5 0.71 F. quadrioculata 0.7 1.9 2.8 0.40 F. candida 2.9 38.5 13.4 0.18 I. -productus 0.2 0.70 3.0 0.40 ,r I. thermaphila 3.8 46.6 12.4 0.30 I. viridis 3.2 90.3 28.5 0.13 Acari P. crassipes 4.8 29.9 4.9 0.14 P. punctum 8.6 329.4 38.4 0.32 Pygmephorus sp. 5.7 68.6 11.9 0.57

* For other details see Table (a) Althouish ,gorse of tho distrubJtione fitted the Neyman-type A,

the Negative binomial ;cries, was a much better description yielding nine out of eleven good fits. A good fit to the

Neyman-type A, of Isotomodes productus distribution was also similar to the findings reported by Debauche (1962).

Southwood (1966) reported that the parameter k of the negative binomial distribution gives a measure of dispersion; the smaller the value of k, the greater the extent of aggregation. Therefore, present findings indicate aggregation amongst most of the species of Collembola and Acari studied. The majority of the k values were less than 1 indicating a trend towards a Logarithmic distribution.

Nef (1962), studied the distribution of various species of Acarina and found that the negative binomial was a good fit and the distribution of three representative mites of Gamasina, Prostigmata, Cryptostigmata confirmed

this for the current studies. He indicated that the con-

clusion can be generalised to a number of other animals.

Southwood (1966), has mentioned "the aggregation

recognized by the negative binomial may be due to either

active aggregation by the insects or to some heterogenety

of the environment at large (Micro climate soil, plant,

natural enemies)".

The aggregation of Collembola could be due to several

reasons:-

(a) Aggregation of eggs is a quite natural phenomenon.

However, Poole (1961), showed that aggregation of

Collembola is not related to egg clusters by comparing the 48 co--efficient of dispersion of egg batch sizes of different species. He pointed out that the co-efficient varies inversely with the egg batch size. Nevertheless, after the eggs have hatched slow disrersion of individuals could preserve the aggregates. Thus a pronounced difference in the motor activity of individuals would tend to set up aggregations in relation to growth stages, and the age within the life cycle. Species of euedaphic Collembola like 0. trinotatus,

T. krausbaueri, F. candida and I. productus are considered to have less developed locomotory organs (Gisin, 1961;

Christiansen, 1964), and it is a reasonable assumption that higher probabilities of their aggregation could have been caused by the type of the ir locomotory organs. Haarl& (1960), contended that the better the locomotory organs are developed, the less aggregated is the distribution of species. This seems to be a geometrical explanation, assuming the hatching centre as a source of migration in all directions the density at any point would tend to be inversely proportional to its distance from the centre.

(b) Aggregation has been attributed to the gregarious instinct by Davies (1932) and Palct (1956). It is extremely difficult to prove this hypothesis, but nevertheless cannot be refuted.

(c) No doubt, animal behaviour is dominantly guided by instinct, and in this case, food-seeking seems to be a contributary cause of aggregation.

Hale (1967) suggested that aggregations could arise from egg-batches, gregariousness, or the coming together of 49. individuals At a food source. Usher (1970), has recently further analysed factors reeponsible for aggregation and has correlated various factors with aggregation of

Collembola, including egg batches and food resources. The biological significance of aggregation in Collembola populations has been described by Cole (1946), and Hale (1966).

The sizes of aggregates have been estimated by Glasgow (1939) and ranged between 3-12 inches in diameter. No confirmatory attempt was made in the present work.

There were several additional features which affect the density of populations in soil such as temperature, humidity, soil structure, and organic matter content. For example, most Collembola are confined to the air spaces in the soil, demonstrating the importance of soil structure.

Also it was thought there might be a correlation between the density of population and the organic matter in the core. This can be verified by finding either the organic matter percentage directly or by finding the specific gravity of soil sample as a whole, including all the organic and inorganic constituents. Obviously a significant negative correlation between the faunal density and specific gravity of soil would support this hypothesis.

The specific gravity of the soil sample was determined later and is reported in the results of 1969. 50.

5. Seasonal Distribution

Most workers found seasonal variation in the faunal

density, with a peak in autumn and a minimum in summer,

although this report is based only on observations from

July 1968 to January 1969, with a fair amount of confidence

it can be said that in the areas examined the maximum and

minimum densities of Collembola occurred in winter and

zummer respectively.

Davies (1928) and Argell (1941) have shown that

probably the most important single factor governing the

population of Collembola is soil moisture.

Obviously the rainy months of the year vary from one

place to another as do the population peaks. In Southeast

England about 12% of the annual average rain falls in

December. January 1969 was exceptionally wet month which

is reflected by the high density of the Collembola for

that sample. Early summer, being the driest period, did

in fact produce the lowest figures for soil fauna. This

correspondence perhaps simply supports the hypothesis

that soil moisture governs the seasonal distribution of

Collembola.

6. Vertical Distribution

As observed by many workers, (Glasgow 1939;

Macfadyen 1952; Haarqv 1955; Poole 1961 and Usher 1970),

this present investigation showed that the maximum density

of soil animals in general, and Collembola in particular,

is in the top layer of the soil. Density appears to

decrease with depth without exception on all sampling 51 occasions. By plotting the density against mean depth of the sample on linear graph paper the variation along the depth seems to chance exponentially accordingly to the general form -Kx Y = Ae were Y is the density and x is the mean depth of the core.

The values of A & K were calculated using the pair of simultaneous equations:

(1) Log A 2Y24.0.4343K ixY2 =iY 2log y x21.2 4xy2log y (2) Log AtxY2+0.4343K

To use common logarithms the constant K has been multiplied by 0.4343. The results of such curve fittings for six occasions of sampling are shown in Table12. The estimated values of population density for the given depths are in very close agreement with the observed values.

As the population decreases with depth there mast be a limiting depth where population is expected to be rare, that is when Y = O.

On elimination x = log A - log y -K

Using the common logarithm and y = 1 then

x = 2.3026 log L -K

The limiting depths estimated by this equation seems to be quite reasonable. From July onward with the increase of population the habitat is bound to extend to a greater depth. The limiting depth of 29" during September 1968 against 23" during January 1969 seemed to bo anomalous. 52.

Table: 12 Vertical distribution of Collembola under natural conditions in sandy soil at Church Field

T---- Date of Mean Observed Distri- Estimated Sample depth Popul- bution Limiting"rbensity x(in) ation Best fit Mean max density`` surface depth density (inches) Yo Y= Ye [ 1.7.68 1.5 17.6 18.0 4.5 11.2 23.6e-0* 179x 23.6 18 10.5 7.5 2.0 6.2 13.8.681 1.5 54.8 54.0 -0.226x 4.5 23.7 75.9e 75.9 19 27.4 7.5 16.3 14.0 3.9.68 1.5 55.5 55.1 4.5 35.4 68.6e-0.144x 68.6 29 35.8 7.5 23.7 23.3 3.10.68 1.5 92.8 91.4 4.5 47.7 119.7e-0.180x /19.7 27 53.3 7.5 34.6 31.0 15.1.69 1.5 165.0 166.5 4.5 89.0 238.6e-°'237x 238.6 23 61.8 7.5 32.9 40.2 10.5 10.6 19.8

Population per core (1473 cu. in,) Lower boundary of the habitat 53.

Howovor, thero ovula hr two c:mplRrationc.. for this irregular-

(a) The surface temperature was too high, which led

to the downward migration of fauna, which in fact is the

basis of the high gradient extraction technique.

(b) The meteorological record showed that on

12th August 1968 there was a heavy rainfall of 25.8 mm.

It is possible that eggs could be carried downwards to a

depth of about 29". After hatching during autumn, which

is a gradual process and not an explosion, the fauna

would begin to migrate upwards to a favourable environment

and possibly set up colonies at the depth of 23" estimated

for January 1969. It is reasonable to assume that rainfall

in late snmmer would transfer the eggs from the original

level to a deeper one.

It is evident (Table 2 ) that vertical distribution

in clay soil at High Field is similar but no quantitative

analysis was done as the sampling was from two levels

only.

If one accepts that non-capillary porosity is a

controlling factor of free movement of the fauna and of

removal of carbon dioxide, then it would be expected that

the limiting depth of fauna would be much less in a clay

soil than in a sandy soil.

7. Faunal Group Relationship.

It is evident that the population densities of

Collembola and other Arthropoda are much less in a clay

soil than in a sandy soil, but the density of Acari is 54. more or less the same in both soils (Table10) and are thus less affected by the soil differences. One would also feel tempted to assume that the lower density of Collembola is not only due to shortage of their own requirements but also to predation by Acari. it is surprising that Acari did not show much seasonal variation. However, there is insufficient information at this time to suggest an explanation for this.

To see if any interrelationships exist between different groups of fauna, the following correlation co-efficients were computed.

(a) Between Collembola and total fauna.

(b) Between other Arthropoda and Collembola.

(d) Between Acari and Collembola.

(e) Between Collembola, and total Acari and other

Arthropoda.

The results are summarised in Table136 The correlation between Collembola and other Arthropoda

(excluding Acari) is highly significant and the estimated observed values are in fair agreement.

Quite obviously the Acari is the anomalous group and densities do not seem to reflect trends in the Collembola and other Arthropoda numbers.

To determine the denendence of Collembola and Arthropoda and Acari densities a multiple regression analysis was done and the multiple correlation co-efficient (R) was calculated. 55. Table: 13

Correlation between the mean densities of different groups of fauna extracted from the surface layer of sandy soil (control plots) at Church Field

Expected y Observed y

(a) Between Collembola (x) and 22.3 23.3 Acari + other arthropoda (y) 46.2 51.9 r = 0.9848, p 40.01 56.7 49.8 Y = 1.38x + 2.42 65.9 62.5 99.3 102.1

(b) Between other arthropoda 17.5 10.3 (x) and Collembola (y) r = 0.9615, P<;0.01 22.1 23.4 Y = 4.2x + 7.4 26.7 314 34.7 38.2 61.2 58.4

(c) Between Acari (x) and (d) Between Acari (x) and other arthropoda (y) Collembola (y) r = 0.6682 p>0.1.0 insig- r = 0.6498. p>0.1Q (in- nificant significant)

Ze Zo

(e) Dependence of Collembola 17.4 10.3 (Z) on other arthropoda 22.4 23.4 (x) and Acari (y) jointly:- 26.5 31.6 R . 0.9616 = p 0.01 34.6 38.2 Ze = 4.15x + 0.06y + 7.12 61.1 58..:4 • 56.

Apparently R is highly significant accounting for 2 92% (p ) of the variation in (Z) and the estimated values of Collembola from the given values of other Arthropoda and Acari are in fair agreement with the observed values, but comparing the estimated values in section (a) and (b) with the estimated values in section

The small contribution of Acari in the multiple regression equation, compared with that of other Arthropoda, is expected from the poor correlations shown in section c

(Tablel3). It would seem from these results that Acari are influenced by factors other than these operating on the Collembola and other Arthrcpoda which vary together.

That Collembola and - the other Arthropoda (excluding Acari) vary together does not necessarily indicate causal relationships between them but probably only that the same general soil conditions, and possibly climate conditions, influence their numbers 57.

_ 8. Pei7piptence 0;c_.4.1icprb.54nd_Ljnol2ho,g_ in_churphield - (sandvsoill_ 1963 - 126Q 3-4" Soil samples were taken from 0-3"/and 6-9" depths 'DART .sue momthsafter the insecticide application. The

species list of Coller.lbola, Acari, and other

arthropods extracted are listed. in Appendix 1, 2, 3, 4, 5.

The effect of pesticides on the 7pooulation of

arthro73ods was monitoted up' to C months after

insecticidal apthcation. It w=7.8 found convenient to

present the mean numbers recovered in treated plots

as percentages of the mean numbers recovered from the

control 'mots (Fig. 8 ). The method

of extraction was 1ml:roved later, and better

information on the soil fauna is available for the

1969 and 1970 trials. However, since the trends of

the pesticide effect should be the same it is

considered ap?ropriate to incorporate the 1968

results to indicate t7le effects of pesticide

treatments on t17.2 fauna in the 0-9" soil profile.

'ZinophosIb2d a more drastic effect than aldicarb

on Acar1 and other arthropods but the populations of

Collembola were eoually affected by both insecticidesorrle

mom ths after a-_pplication. Recolonisation was ra-pid

in subsequent months but the :Po.zYulation build-tu.) of

Collembola plots in aldicarb treated plots was

creater than in the l no7"ros'treate(f plots. 58.

I 1 140 ALDICARB ZINOPHOS (Treatment in May 1968)

O COLLEMBOLA 120 • ACARI 0-9" • OTHER ARTHROPODA

100 _

80 0

0 U 0 60_ ♦

JULY AUG. SEPT. OCT. JAN. 1968 1969

Fig. 8. Effects of aldicarb and -linophos broadcast in May 1968 on Collombola, Acari and other Arthropods

at Lower Church Field, Silwood Park (0-9" depth). 59.

Interaction of predatory mites with the

Collembola appeared more prominent during mid-autumn.

Collembola exceeded. the control population in the alciicarb treated olots pres-,;mably as a result of a decline in predatory mites, whereas in the .minoohos olots recoveries of these mites aporoached. normal and thereby Collembola were reduced significantly.

Populations of other arthr000ds were also affected more drastically in i7inoohosI treated plots than in aldicarb, but after 3 months (January, 1969) their number exceeded the control population by 20. Acari showed higher susceptibility to aldicarb than N2Inophos l while the tolerance of Collembola was reversed to these insecticides. Po2ulation densities of Acari and Collembola could not reach the level of the 1 . control population even 0 months after Ilnophos treatment. The total numbers of the fauna in the aldicarb treated Lot increased more than in the control. This might indicate that perhaps the toxic metabolites of aldicarb were reduced to non-toxic levels and possibly the insecticides had some stimulatory effect on the reproduction of arthropods. 60.

, 9. IDer..,-istence._o:•::.' ,t44i.carb_ and 1 ±no T1.41 so-'1] o6C - 1 960

Soil samples were taken at the Grassland Research

Institute, Hurley, from July 1963 to l'iay 1969. Data

were pooled for 0-6" cores and comparisons were made

similarly as re-Dorted for Church Field(Fig. 9). It has already been stated that the carbamate and the

organophost3horus pesticides were .less persistent in

the clay soil on the basis of chemical analysis and

census records of the fauna. Tslo months after soil treatment the population of sprin:stails was found

lass in aldicarb than ininoohosi treated T)lots.

Comparing populations for each insecticide treatment

mites were less affected than Collembola by both

insecticides. Recolonisation by Collembola was progressive and

conspicuous and the populations in the aldicerb treated

plots out-numbered the control population by 40% after 1 year. Precision of the census records would no

doubt be affected up to 5 months (October, 1963) due to the less efficient method of extraction. Therefore

counts after 12 months would give more accurate data

on the persistence of the pesticides on the basis of

arthropods numbers. It has been reported that the rate of loss of

-anophosis very rapid in clay soil and it is several

times less "persistent than aldicarb (2ain and Skrentny,

1969; Full. 1963; Goir;in, 1967). Rollover 61.

/ / ,

e' .0' k

0 0

0 a 0 a. 17.1 U, DA O OP

R O A L BO AR TH kA ER TH O D

1 I 0 0 0 0 0

Fig. Effects of aldicarb ands i.nophosi broadcast in May 1963 on Collembola, Acari and other Arthropoda

at High Field, Hurley (0-6" depth). 62.

t712 1:-)69-1970 oxi,orimeuts plcacarb was detected

after 12 months,(Srentny,1970;,Appendix Table 44 but by extrapolating the concentration oflinophos from published data (:Pain and Skrentny, 1969) it may be

seen that traces of'Zino-ohos'are extremely doubtful after 12 months. However, even small quantities of

''Zinophosi may:.,rove sub-lethal to species. Values for

LE1, and. LC10 calculated from the regression

equations for'lainopl.7.os- '(Table 30) gives 0.0014 pnm and 0.0063 ppm concentration resoectively. Such low

concentrations are difficult to detect by the GLO

method of -Pain and Skrentny (1969). Scopes (1965)

showed that Folpopia species was sensitive to

0.003 opm of"Zinonho& and he found hir:her residues

than this in treated fi-lds 760 days after treatment

for application rates close to that used in the

present studies. Griffiths and Bardnel-'s (1964) bio-assay on the control of wireworms revealed that

Zinophoswas persistent up to 259 days; therefore,

there are oossibilities thatnophos' was persistent in the field in ouantities and may be toxic to the soil

organisms extracted. Notwithstandin this information the 9resent-

work indicates that'Zinonhos'was less persistent than

aldicarb and, but, even so, it drastically affecte4

the ecosystem and the number of soil invertibrates

remained lower than in the control 'plots even after 63.

12 no:.-1-hhe. 11n long -uerm effect of aldicarb 'was

greateron mites than Col]owbola uhich is the reverse

of its effect up to -5 months after treatment.

Similarly other arthropods were more affected than

mites by aldicarb.

Thus clay soil )rov(.d to be less effective than sandy soil for maintaining the bersistence of the

pesticides used. ILxtensive cyan es in the population

balance of prey and predatory groups were noticed in

,sandr,apd7.claysalls.,aftep2111;-99.;1 9f al,c4ep,rb 9nd

1 . Some effects. of cultivatThn bi the. soil fallna. during: A942

12.s conoide'rahle idisac-rea;2d4

:literature'concernin,, t71.

Gbliexabpip nsan. 96_ ottgla.3:11 g •ond. rotovation uere.carried out. before ,sowing potatoes/ • ..• and a ceLlterisen of the ,fauna -9f t3,-.1.9 runtreated

January, ,

rotovatee. .477.7 . 1, 1269", n the control and

treated :olots., Fauna,'wers extraeted 2 weelts aftor

rotovation. The ithestigation was-aimecl at firiding

out only some .possible efi'oct of ciAtiVation on the,

• fauna. of 0-12" soil depths, as the census, just

before the cultivation was not known. ROtovation was

carriee. out u.,? to G" soil depth, and it is

intorostino to rocord from the verticai'distribution ''':4

plots on Collembola, Aea'ina and 0#0r Arthropoda in 0.12" depth. Collembola • 1. Onidhiurusap

2. T. Itrauabaueri

FoIsomiAPP, 4. I. la-cduQtuc thermilta2

I. viridis 7. ,sminthuridae..

8. Neelus minimua.

9. Mesoetigmata 10. Prostigmata Arthropoda (except Collembola and Acarina) 11. Insecta and Larvae 12. Other arthropods UNCULTIVATED NI CULTIVATED CONTROL

H 1 2 3 611 7 8 9 10 11 12 EPT

2.0 e D l

0- 1.5

U AL O 0.5 0

0-0 1 3 4 6 8 9 10 II 12

2.0 1

1.5- HOS OP 1.0 IN Z o 0.5

0-0- 1 2 3 4 5 7 8 9 10 11 12 I I I L I COLLEMBOLA ACARINA O. ARTHROPODA 65.

(Fig. 10) based on ten pooled random samples from each treatment before and after ploughing that major chnages did not occur below 6" depth e.g., T. krausbaueri, I. productus,

Prostigmata. In the control plots cultivation had varied effects on populations of Collembola, Acari and other arthropods but gener-lly caused obvious decreases (Fig. 10).

However, a 10 x increase was observed in I. therwhila after rotovation, but this might be due to seasonal changes or aggregation. Maddison (1969) has also mentioned increase in the density of I. thermqphila after cultivation.

Remarkable increases in the population density of

I. ILEAphila in control and treated plots indicate also the possibilities of maxima at the time of sampling. Results from the treated plots were also close to control observation considering the overall effects and the rate of population build-up for the long-term effect of both insecticides

(Figs. 8, 9). Present results contradict the finding of

Schalk (1968), that "cultivation had no apparent effect upon

Collembola but it did affect Oribatei and Acari." 66. SECTION II.

THE EFFECT OF ALDICARB AND IgINOPHOSI ON SOIL FAUNA IN TWO SOIL TYPES, SANDY AND CLAY SOIL AT CHURCH FIELD AND HIGH FIELD 19675=-1970 The previous experiment, 1968-69, evaluated some of the responses of the soil fauna, broadly divided into three groups, to aldicarb and-iinophos'in two soil types, sandy and clay. Some attempt was made to examine responses at the species level but since the sampling and extraction methods had to be modified during the course of the experiment only general trends could be interpreted with any confidence. Therefore the experiment was repeated in

1969 using the improved techniques and with greater emphasis on the specific responses to the pesticidal treatments. It was also possible to consider more species including some of the rarer species which were extracted in larger numbers than hitherto.

The separation of the samples into 13" depth cores

was expected to produce more uniform efficiencies o2

extraction at all sampling depths and thus an examination

oPthe vertical distribution was given greater attention.

In addition other workers were using the same plots

to evaluate the persistences of the insecticides. It was

anticipated that this information would be invaluable in

the interpretation of population trends.

The methods of analysis are presented in Appendix 5A( p. 279-80). 67.

1. Methodand experimental•design

The layout of field experiments is shown in

Figures 1, 2 for Lower Church Field and High Field

Grassland Research Institute Hurley respectively. The

fertilisers applied, herbicide (Grammaxane W) dosage and

method of application of the pesticide and sampling were the same as described for 1968 (p.16 ). The plots were again planted with the potato variety, Penland Dell, in

April 1969. 'Zinophaand aldicarb, 10 lbs active ingredient

per acre were applied to the appropriate plots on the

13th May at Hurley High Field and on the 16th May at

Lower Church Field. Monthly soil samples were taken at

random from each plot.

On each sampling occasion five random samples were

taken from each plot, the vertical distribution of fauna

was studied by dividing the 0-12" cores into four depths,

0-3, 3-6, 6-9 and 9-12 inches, using (1.5" core) gi-ring a

total of 120 soil cores from each block at Church Field on

each occasion (Fig. 11).

At High Field, 4 random samples were taken and each sample was divided into 0-3, 3-6 and 6-7.5 inches giving

a total of 120 soil cores from all plots on each occasion.

The results of the statistical analysis of the

distribution of Collembola and Acari (p.44) indicated

that their distributions were patchy and this was best

described by the negative binomial distribution. Since the

negative binomial was found to be a good fit the mean of

raw counts were transformed to the common logarithim of n 1. 68.

Fig.11. High Gradient Extractor (1.5" core). 69.

Bio-assays were carried out using aldicarb and its

sulphoxide and sulphone metabolites extracted from

contaminated soil and using contaminated soil by itself and

also iiinophosi (technical grade) as described in the

bio-assays section (p.145). The analysis of sensitivity

of some Collembola species to field-applied pesticides are

also described later. The residues of aldicarb sulphoxide

and sulphone (Skrentny, 1970) for the period during which

these studies were conducted are included in Appendix

to aid interpretation of the persistence of aldicarb. 2. Results

(a) Lower Church Field,Silwooa Park

Most of the experimental work on the persistence of

aldicarb and iZinophosi was carried out during May - November,

1969 although samples in May, 1970 were also taken to

evaluate the long-term effect of the pesticides. The

//wen. h st, tRS majority of Collembola, Acarina and other ar4liPeplasee

recorded during the period of experimentation could be

identified and are listed in Appendix 1, 2, 3, 4, 5. It was difficult to present conclusive results on many of the

infrequently occurring species and they are therefore only

categorised under the suitable order or group. The vertical

distribution of soil animals ts shown in Figs. 12 - 20

and their contributory proportions to the mean population

of the whole soil fauna are presented in Tables 14a, b.

Estimates of the population fluctuations in Collembola,

Acari etc., and the difference in the composition of all 70.

fauna are also incorporated in Tables 14a, b to

determine the changes in composition due to pesticide

treatment. The overall effect of soil treatment of insecticide on the increase/decrease of soil fauna is indicated in Table 15.

It is evident (Table 15 ) that in the 0-647 and 6-12" respectively, profile the Collembola population was

decreased 34.6/ and 13.5% in the aldicarb plots and 55.6% and 22.1% in ikinophosi plots. Acari were decreased 62.2% and 37.1% due to aldicarb and 76.0% and 68.6% due to —Linophos'

and that i2inophos was thus more toxic in effect than r aldicarb. Other insects species and other 41.-Wa

showed a similar response to both pesticides. These

findings also indicate some information regarding tolerant

and susceptible species which may be an outcome of oompetition between species due to a predator/prey

relationship. The population composition of Collembola

was increased, and Acari decreased, during June to

November in all levels of both aldicarb and'Zinophos i

treated plots in comparison to the control (Tables 14a, b).

Insects and other micro-arthropods showed a mixed

response to the pesticides. Observations on the individual

species/groups are given below. 71.

Table: 14 (a)

Effect of Aldicarb and aZinophoston the composition of the population of totalinvti-ftbr-40sin sandy soil (0-6" depth) during June to November, 1969 (Percentage)

•. Population within A, B & C Control Aldicarb'Zinophos Control Aldicarb 'Zinophosl

A. Collembola Onychiurus sp. 2.0 0.5 0.2 2.3 0.5 0.2 T. krausbaueri 81.4 90.9 92.0 92.0 98.5 99.6 Lepidocyrtus sp. 0.7 0.2 0.0 0.8 0.2 0.0 Folsomia sp. 1.1 0.3 0.1 1.5 0.3 0.1 I. productus 1.5 0.1 0.0 1.7 0.1 0.0 I. thermuhila. 1.0 0.0 0.0 1.1 0.0 0.0 I. viridis 0.4 0.3 0.1 0.4 0.3 0.1 Sminthuridae 0.2 0.0 0.0 0.2 0.0 0.0 Neelus minimus 0.2 0.0 0.1 0.2 0.0 0.1

Total 88.5 92.3 92.4 100.0 99.9 100.1 B. Acarina Mesostigmata 7.7 3.4 3.0 76.1 55.3 52.8 Cryptostigmata 0.1 0.1 0.1 1.0 1.8 1.4 Prostigmata 2.1 2.5 2.1 20.6 41.2 37.5 Astigmata 0.2 0.1 0.5 2.3 1.8 8.3

Total 10.1 6.1 5.7 s100.0 100.1 100.0 C. Miscellaneous Insects and larve 0.5 0.5 0.-4 34.1 33.3 20.8 Other invertebrates 0.9 1.1 1.5 65.9 66.7 79.2

Total 1.4 1.6 1.9 100.0 100.0 100.0

72.

Table:14 (b)

Effect of Aldicarb and'Zinophos) on the composition of the population .. of total invertebrates PaAdTs763-±75,70277.-adiSTET-Turing June to November, 1969 (percentage)

Arthropods Mean number Population within A, B & C species Control Aldicarb Zinophos' Control Aldicarb 'Zinophos'

A. Collembola Onychiurus sp. 0.3 0.3 0.1 0.4 0.3 0.2 T. krausbaueri 75.8 . 87.5 90.7 88.5 98.0 98.5 Lepidocyrtus sp. 0.2 0.0 ' 0.1 0.3 0.0 0.2 Folsomia sp. 2.1 0.7 0.7 2.4 0.7 0.8 I. productus 6.6 0.7 0.0 7.7 0.7 0.0 I. thermqphilla 0.0 0.0 0.0 0.0 0.0 0.0 I. viridis 0.0 0.1. 0.0 0.0 0.1 0.0 Sminthuridae 0.0 0.0 ' 0.0 0.0 0.0 0.0 Neelus minimus 0.7 0.1 0.5 0.8 0.1 0.3

Total 85.7 89.3 92.4 100.1 99.9 100.0

B. Acarina Memostigmata • 9.4 7.2 4.2 70.2 70.5 71.8 Cryptostigmata 0.0 0.0 0.0 0.0 0.0 0.0 Prostigmata 3.5 3.0 1.3 25.8 29.5 23.1 Astigmata 0.5 0.0 0.2 4.0 0.0 5.0

Total 13.4 10.2 5.5 100.0 100.0 99.9

C. Miscellaneous Insects 0.3 0.3 0.0 37.5 50.0 0.0 Other invertebrates 0.5 0.3 2.1 62.5 50.0 100.0

Total 0.9 0.5 2.1 100.0 100.0 100.0 73. Table: 15

Comparison of the mean population number per core between aldicarb,ilinophosi treated and untreated plots in Church Field from June to November 1969(as percentage of control)

Aldicarb 'Zinophos' Aldicarb 'Zinophos' 0-6" 6-12" Collembola 65.4 44.4 86.5 77.9 Onychiurus sp. 14.8 3.3 66.7 33.3 T. krausbaueri 70.0 48.0 95.7 86.7 Lepidocyrtus sp. 63.6 0.0 0.0 50.0 Folsomia sp. 18,2 3.0 26.3 26.3 I. productus 4.4 0.0 8.2 0.0 I. thermqphila 0.0 0.0 0.0 0;0 I. viridis 45.5 20.0 0.0 0.0 Sminthuridae 0.0 0.0 0.0 0.0 Veelus hinimus 0.0 16.6 16.7 33.3 1Jcarina 37.8 23.9 62.9 31.5 Mesostigmata 27.5 16.6 63.2 32.2 Cryptostigmata 66.7 33.3 0.0 . 0.0 Prostigmata 75.8 43.5 71.9 28.1 Astigmata 28.6 85.7 0.0 420.0 Miscellaneous 73.2 58.5 50.0 175.0 Insecta 71.4 35.7 66.6 0.0 Other in-ve.:1..-relii-a.`-res 714-.1 70.4 40.0 280.0 74.

(1) COLLEMBOLA

Onychiurus sp.

The numbord in the conLrol plot were greater in the

0-3" and 3-6" layers than in the pesticide treated plots.

Population peaks in the lower depths were evident in

September and the species were found in abundance during

October. This probably indicates that egg batches were

laid at a depth of 9-12" (Fig.12). The species probably

preferred comparatively less moisture for breeding as the

rainfall was at a minimum during September and October.

Low temperature did not seem favourable as low recoveries

were observed during November.

Evidence for interaction between Onychiurus and

gamasid predatory mites was not conclusive.

As the toxic residues of aldicarb began to disappear

from the top layer (Appendix Table 6) the populations built up during October but recoveries from lower layer; did

not confirm the presence of higher toxicants at a greater

depth.

'Zinophoss caused a greater decrease in the population.

It was perhaps more confined to the top layer and was

comparatively less persistent in lower layers than the

aldicarb. In the 0-6" layers aldicarb reduced the

population by 85.2% while'Zinophosi was more effective

reducing the population by 96,7%. At 6-12" depth"tinophos/

remained twice as toxic to the species than aldicarb

(Table 15 ).

75.

22.12.1-J1151LLIE- o—e Control e— Aldicarb

41" Zinophos ' I.5 Treatment 11 0-3 7q5.1 Z t /, 1.0 1

0.5 0.e... % s P 2. s- ....,.., AL- ./ I ••■ z 1,... , , ...... ®' ... ••00 ...... 6 , -of i 'N.A.-. -' --A- • - • -4, -; 4•-. -A.

l.0

0.5

0.0

0 1.0 6-9"

0.5

0.0_

0.5 9 —1 20

0.25

o . o F M A J A 50 1 9 6 9

Fig. 12. Effect of aldicarb and'ilinophos'on

Onychiurun np. Church Field 1969. 76.

Tulibergia krausbaueri

The population of this, the most abundant collembola species (76.81%), was found to gradually build up until

October (0-3") and September (3-12"), after which a steep fall was observed. The delayed peak in the 0-3" layer could be due to an upward movement from the lower levels or perhaps more favourable condition for increase (Fig. 13).

Observations of the relative abundance of juveniles in the lower layers suggest that egg batches might have been laid below the depth of 6" moreover, increases in the gamasid population, especially nymphs, at the same time could have also been responsible for this fall, but only as a secondary cause,

'Zinophos' was more effective than aldicarb in 0-3" and 3-6" layers but response in the lower layers were varied.

During the course of this investigation the proportion of this species to the tOtal,compo'sition of the fauna population was increased in both the treated plots, this may be attributed to less competition, i.e. fewer other non-predatory and predatory species, to some stimulatory effect on this species, or to dire6t or indirect changes in detritus and available or,anic matters due to the pesticide. T. krauchaueri was found to be a tolerant species on the basis 'of its appearance in the treated plots and i1;1 bio-assays. In the 0-6" layer its population was decreased 30% by aldicarb, and "Zinophost reCuced it by 52% (Table 15),

Population estimates may not truly reflect the toxic effect as a considerable reduction in the population of predatory mites could also have had an effect,

77.

TULLBERGIA KRAUSBAUERI

• Control

30 0-3m • Aldicarb Treatment a_._4•ZInophos s

2.5 2.5_ Treatment 6-9m .,.. -•--• , ....e.. 2.0 obi ..... N. 2.0 ••••..•••= "A - w::.,41-. . la N.A...... a d • ,... 1 1.5 / 1.5 ,

- - - 1.0 1.0

0.5 0.5

"0.0 0.0 • as 3_e O P-- • •._ 9-12" 2.0 -a 2.0 111

1.5 1.5 6, "--A/ 1.0 S.

0.5 0.5

0.0 0.0

J FM A M J JASON JFMAMJJAS ON 1969 1969

Fig. 13. Effect of aldicarb andlinophoe on T. krausbaueri Church Field 1969. 78.

Lepidocyrtus sp.

This surfaoo-Lype apecies showed two maxima in the

0-3" layer, namely during August and October - the highest concentration being recorded in the latter month. The number in the 0-6" layer was three times that of the 6-12" and, during favourable seasons, the species was found in deeper layers. Both aldicarb and tinophos proved to be lethal and the population recovery was very slow up to

November. During June to November the population in zinophos (0-6") and aldicarb (6-12") - treated plots was completely destroyed although both insecticides were comparatively less effective in the second half of the soil profile.

Reasons for the rapid build-up of density in top layers seems to be due to the degradation of the toxic residues (Fig. 14 and Appendix T. 6)in aldicarb treated plots. There is no firm evidence for migration to treated from untreated plots.

Folsomia sp.

These were found to be more active down to 9H in depth

but beyond that depth their numbers were considerably

decreased. Composition of the species in the 0-6" layer was only half that of the 6-12"(Tables14*lb).The 'three-maxima

(June, August and October), were quite distinctive in these

Collembola and minima occurred during the intermediate months

(Fig. ilt). Drastic reduction in the population of thtse

major species was recorded after insecticidal treatmentparticul- arly in the 0-6" levels. LEPIDOCYRTUS Sp. FOLSOMIA Sp.

•---• Control

• - - -0 Aldicarb

• —A"Zinophos"

Treatment

1.0 3-6" i.ol- A,-z., 3 -6" 21 2I

IX 0.0 0-0— • • - • - • - • -.A... r

0 -J a5 6 -9

025

0.0

O. 5 9 -12" 1.0

0.25 05

0.0 0-7-1 r- r• • T.I JASON A SON FMAMJ J ASON 1969 1969 80.

'Zinophowas about six times more toxic than aldicarb in

0-6" layers but nietherinsecticide had marked .effects in the'6-12" layers.. Laboratory bio-assays. revealed 0.1 ppm (aldicarb sulphoxide plus sulphone in the contaminated soil) as an LC50for E. fimetaria, but in the field in October when the residues were estimated as 0.25 ppm (Appendix Table 6) the population had built up to 50% of the contral plot. In

lower depths (6-12") the detected residues was 0.5 ppm for the same month and the population count was two-thir.du

of the control.

I. productus This was the third most abundant species of collembolan

(Tablel1+a). Tts ceasona3. distribut:Lon .(Fig„ 15 ) indicates that the species has a comparatively short life span, peaks and dips being at monthly intervals. Its movement

in the soil down to deep layers is probably due to the porosity of the sandy soil. The species was highly

sensitive to the organophosphorus insecticide. Zinophos and aldicarb reduced the population 100% and 95.6%

respectively in 0-6" layers. The higher population increase

in lower layers of aldicarb treated plots might be partially

due to decrease in the number of predatory mites (Fig.18).

I. thermqphila On the basis of vertical distribution (Fig. 15) the species could be categorised as surface type. 81.

ISOTOMINA THERMAPHILA ISO TOMODES PRODUCTUS •-• Control 0- - -• Aldicarb

Treatment Treatment 0-3” I.0 1.0 0-3" 1 0.5 0.5

, 0.0 0.0 a .„. •—• -A' 2.'4

3-6" 1.0

0.5

• • 1 0.0 Ix

1.5 6-9"

9-12" 1.0 9-12" 1.0

0.5 0.5

00 0.0 .4! • • •r- -1 • -44-• • • T- • ;:.•(- • -44 JFMAMJJ A S O N J FM A M J J A SON 1969 1969

Fig. 15. -Effect-of-aldicarb and lUophos'on Isotomina

therm9phila and Isotomodes productus.

Church. Field 1969. 82.

Very low rocoverioo from tho tro,Ated field fully support that this species was one of the worst affected, and during the period of observation it failed to recolonise.

Perhaps residues of pesticide were high enough to prove lethal to any recolonisation efforts made. No correlation of the abundance of I. thermnphila to the weather could be definately established.

Isotoma sp.

Like I. thermqphila this unidentified species was concentrated in the top 3" of soil. (Fig.16 ). The insects' recolonisation was rapid and population fluctuations in treated plots coincided with those of the control.

The appearance of a few species in the lower layers of aldicarb-treated plots seems to be due to the patchy distribution (Table11a). The population was anihilated in'linophos treated plots.

Sminthuridae

Summer and autumn peaks were evident in all layers although the summer peak appeared a month late in the surface layer of the untreated plot (Fig.16 ). The species were mainly confined to the top layer. Gamasids were lowest in July in the aldicarb-treated plot and conseauently sminthurids appeared in abundance during the period.

The overall low yield of Collembola prevented the accurate measurement of the effect of the pesticides and it is evident from Table 15 that the toxicants had similar effect in the 0-611 and the 3-11" layers. ISOTOMA Sp . SMINTHURIDAE • Control • - -. Aldicarb 15 _ Treatment • -A IZinophos 0-3" Treatment 0-3"

I0 _ 0.5

•. 0.25 0.5 1, •

• Doh .0

I.0 3-6" 0.5 3- 6"

0.5_ es. 0.25

41 A-- t 0.0_ • 0. 0_ •.

D 0 0.5 6-9" 0.5 6-9" tui or 0.25 • 0.25 / S R • . / \ / liT •._ 0.0 / \ 0. 0 PT 6 0.5 9-12" O. 5 9-12" 69 '

0.25 0.25 a.,

0.0 • . • , r , • . Y' -•. — -r • -r JFMAMJJ ASON J F MAMJJ AS ON

1969 1 969 84.

Neelus minimus

This Collembolanwas extracted slightly more in

number than Sminthuridae but they were mainly subterranean

(Fig. 1 7, Table 14t, b). '2inophos was less persistent in lower layers than aldicarb and aldicarb was more potent

in its toxic action as it caused tctal destruction of

Neelus in 0-6". Compared to the effect ofiZinophos%

(6 times decrease) aldicarb proved to be twice as toxic

in the 6-12" layer. This was the only genus which showed

less sensitivity to the organophosphorus insecticide than

to carbamate in the whole of the fauna (Table 15).

(ii) ACARINA

Mesostigmata

The population of these mites comprised 7.7% and

9.k% of the soil arthropods extracted from control plots

and 55% and 71% of the Acarina, in 0-6" and 6-12" levels

respectively (Table 14a b). Population maxim occurred in all layers during the autumn. Population densities were

significantly increased after September and a similar

trend was observed in the treated plots. During counting

it was noticed that the higher mean values (Fig. 18 )

were due to a majority of nymphs. These organisms were

twice as susceptible toi/inophos'than to aldicarb (Table 15 ).

The different residues of aldicarb sulphoxide and sulphone

in 0-6" and 6-12" (AppendixT.6) are not associated with a

proportional fall in those mites. 85.

NEELUS MINIMUS

*---• Control - Aldicarb A. ---A/ZInophosj Treatment 1.0 0-3" — •

0.5

0.0

1.0 3 - 6"

0.5

— 0.0 41.• Ix

(9 I.0 6-9" 0 -J •

0.5

0.0_

1.0 9-I2"

0.5

0.0

JFMAMJ JA 0 N 1969

Fig. 17. Effect of aldicarb ondiinophosl on Neelus minimus. Church Fi °Id" 1'99.

86,,

MESOSTIGMATA Control o --® Ald Ica rb - •-A sZinophosi Treatment 2.0 0-3" Acxt oft,z, 1I, c1 1.5 _ o Z1 /1 /A1 // A • \ A 10 _ 11,z 1// • / •/ ■ Aell 0 \ ,.°/ VA /° 0.5 '',%- ",:',2,74---...... e _ ...0... ti: ‘if •■ - ../. ..."A-.-.-11 •...... il 0.0

u 3-6 1.5 7.4 /It

0 A.... / At 0 \ . -1 0.5 - . ...,-0 \ '• •... ------„,--„-- ...,A, Al '''s ..--. -. .,‘3 -,,.:v.f.1...... --;.." 0.0

1.5 z, 6-9"

1.0

0.5 A.„ _____-o...,,...... " -.4 \ ./ i ■ , G----:-`": - _ ..o -' ..... `t"-3 v -4./ p 0, 'A --... . \ / ...0 0.0_ 0-- - .".A...•' o

9-I 2" 1 .0 / \ \\to 0.5 ''6.— \44., r 0 \ f.„4„:"...... A.N._ AY s. •‘ ,411, ../ •,1/4-S7"-- ./ i ..0 ___.---CP;" . / \ \ l....* 0-..-- r — —0 • , •,0,-- o.o ■ --r---'--A< , -1 4.'"P —.1 -1---, J F M A M- J J A SON 1969

Fig. 18. Effect of aldicarb and 7inophoot on Monootigmata. Church Field 1569, 87.

Cryptostigmata

These were mostly surface type saproghagous mites.

Major population peaks appeared in mid-autumn in the

0 - 3" layer. Their distribution was sporadic in other

layers (Fig. 19). The apparent, although insignificant,

increase in population in June in treated plots might have

been due to the abundance of food, most dead soil animals,

being found during this month. It appears from Figure 19

that mites belonging to this group had a longer life cycle.

Prostigmata

Mites belonging to this order were next in number to

the Mesostigmata population (Table 14a,b). Only a few

.species of this order have been rerorted as predators

.(Wallwork 1967). Nymphs were in abundance during upsurges.

A maximum population was observed by the beginning of-autumn

(Fig. 19). The minimum population in June was evident in all

plots. Although 'Zinophos' appeared to have a drastic

effect on the population, in one case (September, 3 - 6")

there was a significance between the population in the

'Zinophos' plot and the control. Observations of the effect

after treatments have revealed excellent recoveries in all

treatments. ,There was an overall increase in the population

of these mites in the treated plots (Table 15). 'Zinophos'

exerted 1.6 times more toxic effect on the population of 6 - 12" than on that of 0 - 6" depth. A similar but less pronounced effect was observed in the case of aldicarb. 88.

Astigmata

These minute soil animals were found at various

depths (Fig. 19). The yield of these mites was always low,

except during July and August when their number was slightly increased in lower layers. Because of their very low populations little variation in their numbers was possible and thus the

effects of the chemicals are not very clear. However, the

substantial increase in numbers in the control 0 -,3" layers in November was not shown in the treated plots.

'Zinophos' might have had some stimulatory effect on their

reproduction as their overall population was increased 320%

in the 6 - 12" layers. Their interaction with predators was not conclusive.

Miscellaneous

Insects and other invertebrates other than those

hitherto mentioned constituted 0.9% to 1.4% of the fauna

(Table 14a, b). August and October were recorded as

favourable months for their successful multiplication.

Most of the insects were concentrated in the top layers and

only a .few sporodic counts were made at deeper layers.

Inset population was decreased by 28.6% to 33.3% in the

0 - 6" and 6 - 12" layers after aldicarb treatment, but the

89.

CRY P TOSTIGMATA 4---0 Control o- AlOicarb —•-elinophost Treatment Treatment 1.0 0-3" 0. 5 6 -9"

1 0.5 0.25

00_ 0.

0.5 3-6n 0.5 9 -12"

0.25 025

0. 0 0 0 a e D

PROS TIGNA ATA 15 0-3"

4 1.0 6-9"

0.5 r,

IA 0 0 0.0 1.5 3-e 0

Zy 1.0 9-1 0,, ■ % 0.5 -.. 1„• ... fb 05 . *..., / ii 74 — . 4"'” .-Iti 0.0 A ,' 0 0_ A ST I 0' MA TA 075

0-3" t 0 . 5 0. 5 6-9"

• A 0.25 0 25 • / \

* ss: 0. 0 0 e

0 5 3-6H 0.5 9-12"

0.25_ 0.25 ••• /\ I A \ e • • O. 0 0. 0 t- .+64 — — • — -r J F MA M J J A 0 N JF MA M J J A SON 1 9 6 9 1969

Fig. 19. Effect of aldicarb and4inophos' on Cryptostigmata, Prootigmata, Asbigmata.

Church Field 1969. 90. effect of 'Zinophos' was twice as great although only negligible recoveries could be made in 6 - 12" lnyers

(Table 15).

Due to the low number, miscellaneous species of other invertebrates were pooled together and therefore only a general idea could be obtnined regarding their vertical distribution and the effectiveness of pesticides (Fig. 20).

The persistence of aldicarb up to November is evident from the dta but the persistence of 'Zinophos' could not be detected from their counts after three months. The occurrence of some enchytreids and pauropods in deep layers was due to the safe zone which provided them with favourable conditions for multiplication, as the population in 6 - 12" was 180% higher in comparison to the control. Similar increase in enchytreids in 'Zinophos' treated plots were reported by Way and Scopes .(1968) and by Maddison (1969). im irrE4s. Arra s OTHER AThrftsot INSECTA & LARVAE

Treatment Control 15 • — --• Aidicarb Treatment 1-4 — - —A' Zinophosi 019 •• I0 0-3"

O OS mt10 os tt 3-6" 1.0

3-6" :3 1 0. 1 - 0.5

IX 6 P sui 0.0L 0.0 69 00 0

rq. 6-9" ur p ri av A : . - 0

1.0 9-12" 0. 5 9-12"

0.5— ■.—..... 025 ...... > 4 •—. / \ e— ... • . . / '• 'co— — 0-0 0.0 •/....5.4.m—ti:1:L...\:, IS -r a—t • 1". • I JFMAMJJ ASON JFMAMJJASON 1969 1969 92.

(b) High Field Hurley

The composition of the clay soil fauna of Hurley

High Field is presented in Table16. The table shows the

proportional change of the various micro-arthropod

composition of the soil from July to November 1969, after

the application of aldicarb and'Einophos: Moreover,

changes within Collembola, Acari and other axaVegarhave

also been interpreted, as they indicate the competitiveness

between species together with abundance/scarsity of the

fauna concerned.

In he top 6" Collembola were slightly increased by

12.1 percent in the aldicarb treated plot whileZinopho' Ss )

decreased the population by 32,2 percent. Mean population

figures are based on samples from 0-3, 3-6 and 6-74-" depth.

It was not easy to penetrate the auger beyond 7.5u in the

clay soil because of its hardness. Fauna extracted from

6-7.5" is only presented to show the vertical distribution

of species concerned (Figs.21.2.4)s.nd ara not used for other

interpretations. The total responses covering the five

month period from July-November (i.e. up to six months

after the application of pesticides) are compared in

Table 16. This table also shows the changes in population

pressure in treated plots compared with that of control.

Comments on each major faunal group extracted are given

below: 93.

Table:16 Effect of aldicarb and iiinophos'on the composition of the population of totaluve),Tebkimsin clay soil (0-6" depth) during July to November, 1969 TTercentage)

' Population within A, B & C Control Aldicarb aZinophost Control Aldicarb 'Zinophoe A. Collembola Onychiurus sp. 3.2 1.6 2.7 6.9 2.6 5.1 T. krausbaueri 32.4 52.7 40.5 70.1 86.2 75.11- Lepidocyrtus sp. 3.2 2.2 4.1 6.9 3.6 7.6 Folsomia sp. .1.9 1,3 3.6 4.0 2.1 6.8 I. productus 0.3 0.0 0.0 0.6 0.0 0.0 Isotoma sp. 3.5 2.5 1.8 7.5 4.1 3.4 Sminthuridae 1.1 0.3 0.0 2.3 0.5 0.0 Neelus minimus 0.8 0.6 0.9 1.7 1.0 1.7

Total 46.3 61.1 53.6 100.0 100.1 100.0

B. Acarina Mesostigmata 16.0 12.5 ' 12.9 42.9 48.2 39.4 Cryitostigmata 8.0 1.3 3.6 21.4 4.8 11.3 Prostigmata 12.2 10.6 13.2 32.9 41.0 40.8 Astigmata 1.1 1.6 2.7 2.9 6.0 8.5

Total 37.2 26.0 32.3 100.1 100.0 100.0

C. Miscellaneous Insecta 3.2 2.8 3.2 19.3 22.0 22.6 Otherlaveie5-1,, a.ies 13.3 10.0 10.9 80.6 78.0 77.4

Total 16.5 12.8 14.1 99.9 100.0 ,loo.o 94. Table: 17

Comparison of the mean population number per core between aldicarb,'ginophositreated and untreated plots in Hurley High Field from July to November 1969 (as percentage of control)

. - . .

. , Aldicarb 'Zinophos‘ 0-6"4 Collembola 112.1 67.8 Onychiurus sp. 41.7 50.0 T. krausbaueri 137.7 72.9 Lepidocyrtus sp. 58.3 75.0 Folsomia sp. 57.1 114.3 I. productus 0.0 0.0 Isotoma sp. 61.5 30.8 Sminthuridae 25.0 0.0 Neelus minimus 66.6 66.6 Acarina 59.3 50.7 Mesostigmata 66.6 46.7 Cryptostigmata 13.3 26.7 Prostigmata 73.9 63.0 Astigmata 125.0 150.0 Miscellaneous 66.1 50.0 Insecta 75.0 58.3 Other wietebft..tcs 64.0 48.0

96.

The decrease in the number in all layers by the end of

autumn seems to be associated with its life history and

the slight increase in predatory mites (see Fig. 23

for Mesostigmata).

Lepidocyrtus sp.

The distribution of these insects was mostly confined

to the top 6". slimmer and autumn maxima are prominent

(Figure 21 ). Their movement in 0-3" and 3-6" is shown in

control extraction. The disappearance ofi7inophoss

residues after four months in clay soil (Pain and

Skrentny, 1969) appeared to assist their rapid recolonisa-

tion and their number equalled that of the control

maximum in autumn. Gamasid mites were more sensitive to

"Zinophos' that) to aldicarb and this might have facilitated

the breeding of the species. The same factors were

probably responsible for the comparatively higher yield

of L. cyaneus in the top 3" during September and October.

Folsomia These were abundant mostly in 3-6" layers and

maximum population concentrations were observed during the

middle of summer and autumn in the control plots and the

population in thel/inophos'plots recovered before those in aldicarb treated plots (Fig. 21 ). Folsomia showed

higher activity in different soil profiles and it is

suspected that this might be due to their oscape from the

97.

ONYCHIURUS 5p. T. KRAUSBAUERI Treatment t--4 Control // •-• Aldicarb I. 5 Treatment 0.75 1 A. --A 'Zinophos 0-3" 0-3" I. 0 0. 5 __...... ---1...... At 10---'..,-- ••••"' ,°"" -- 0 0. 5 . ••••• / A...... -,-, / 0.25 19 \ , .0/ i _...I 0.0L 0.0

0.75 I.5 ti - 3-e I • 3-6" / •

0. 5 I. 0 • '7

0.25 v 0. 5 • p \\ • •\4:, • O. 0 0.0

0. 5

n 0.25

Ix L' 0.0 (.9 0 LEPIDOCYRTUS Sp. FOLSOMIA Sp. 0. 5 0-3" 075 • 0-3" zt / • 0.25 f A c AS 0. 5 9- 7 0. 0 \A"

0.25 I. 0.75

0. 0 0. 5

0. 5 3-6" 0.25

0.25

0.0 •

0 5 6-7.5"

0.25

0.0 MJ JASON ' M J J A SON I 969 1969

Fig. 21. Effect of aldicarb and'Einophos on Onychinrns v T. krau.Dbaueri, Lopidocyrtus Bp., and Folsomia sp. High Field 1969. 98.

toxic residues, apart from thei:., spatially underdispersed

distribution (Tablel1i%) Due to sampling variation and low recoveries no significant treatment effects, couldbe distinguished.

I. productus

In the control plot Only a few individuals were

recovered from the surface layer compared to a relatively

higher number from the middle layer (Fig.22). Optimum

season for their. growth was early autumn. The total

destruction of the population in treated plots indicates

the highest susceptibility of this species among all the

arthropods recovered from the soil in'these studies.

Isotoma sp.

These Collembola were second in number only to

T. krausbaueri although they constituted only 3.5% of

the total fauna and 7.5% of the total Collembola species

recovered (Table 16 ). August and October maxima and

September and November minima (Fig.22) wore probably due

to their short life-cycle, Up to months after

treatment the effects of carbamate and phosphorus

insecticides were not significantd.y different but during

later months l ancronos appeared to be more effective.

For the5ix months after treatment the opuiationoa1 in the aldicarb

treated plotswas reduced by 38.5% and in the"7inophos'plots

by 69.2% compared with the control. 99.

Sminthuridae

Sminthurida were extracted in low numbers from control

plots but they showed a high density during August and

October (Fig.22). Mean values indicate 100% mortality in

17inophosi plots and a 75% decrease in population with

aldicarb in the 0-6" layer (Table17 ).

Neelus minimus

This was one of the less abundant species. These

subterranean Collembola were extracted mostly from the

3-6" layer. Their seasonal fluctuation was similar to

that of Sminthuridae. 'Zinophos'and aldicarb .,ere equally

effective against the population of the 0-6" layer for the

whole of the observation period (Table 17).

(ii) ACARINA

Mites extracted along with Collembola were pooled

under their family/order as, due to low densities, it was

not considered practical to record the species individually.

No significant change could be observed in the Acarina

population after'Zinophos treatment although the species

composition was affected in the aldicarb treated soil

(Table 16).

Mesostigmata

Most of the predatory mites belonged to this group

and they probably formed half of the population of the

predators upon T. krausbaueri (Table 16). These animals 100. ISOTOMODES PRODUCTUS ISOTOMA Sp.

*---• Control 1 , 0

0 - - -40 Aldicor b A -- A Zinophos 0.75

0. 5 0.5

0.25 0.25

0. 0 0.0

0. 5 0. 5

025 0.25

0.0 0.0

0. 5 6-7.58 0. 5 L 6-7.5"

• 025 025 1)

7(+ O.0 0.0 OGC

L SMINTHURIDAE NEELUS.; mimimus

0. 5 0-3" 0. 5

0.25 0.25

0.0 O.0

0. 5 3-6" 0-5

0.25 0.25

0.0 0. 0

0.5 6-7.5" O.5 6-7.5"

025 0.25

Q. 0.0 0. 0 JASON N MJ JA SON 1969 1969

Fic 22. Effect of aldicarb and Zinophos'on Isetomedes Productus, isotoma sp., EALbhFiclac and

Maus minimus. High Field 1969. 101.

seemed to be effected by the chemicals soon after

application but their population densities were not

significantly different from the values (Fig. 23). Over

the period of observation 'Zinophos' and aldicarb reduced

the total numbers recovered by 53.3% and 33.3% of the control respectively.

Cryptostigmata

HThe gradual increase in the population build-up of

these mites is evident in July (Fig. 23). Population

peaks were also eviaent in September an4 November. These

- indications support that the mites have a short

synchronised life-cycle. Maximum populations in all

layers during November might have been due to the presence

Of saprophagous fungi and a fall off of pesticide persistence.

'Zinophos' appeared about, half as toxic to the mite population

as aldicarb (Table 17).

Prostigmata

Mites belonging to this order were active and they

were extracted in moderate numbers from all three layers

(Fig. 23) but the 0 - 3" layer contained 1.2 times more

mites than did the 3 - 6". Population peaks occured in periods similar to those of the other fauna. Although the totals

recovered compared with the contrial were decreased by 26% and 37% for 'Zinophos' and aldicarb plots respectively

there was no evidence.ofH..',significent treatment-effect.

Some of the probable reasons for the 0 - 3" peak in 0ctbber

102.

can be explained by the findings of Waliwork (1967) who

reported that Scutacaridae and Tarsonemidae (included in

thi-1 group) migrate on other soil-dwelling insects.

Astigmata

These saprophagous mites were found mostly below 3"

in depth (Fig. 23). Aldicarb and 'Zinophos' had no marked

effects on the population. There was some evidence that 'Zinophos'

did not effect the population as much as aldicarb. Reasons

for the increase in population in 'Zinophos' plots might be

the decrease in predator populations, more food resources due

to the putrification of dead organic materials and/or migration

from other areas.

Miscellaneous

The control plot population peak for other insects

occurred in September and for other invertebrates in July

(Fig. 24). Aldicarb was comparatively less toxic than

.'Zinophos' (Table 17). Due to the diversity of behaviour /4 b )4. Ala.'s and general biology of the various r- -- involved the

effect can only be considered as a general proportional

response.

103.

MES OST IG MA TA PROS TIGMATA

Treat ment Treatment Ar -311 I. 0 o-Y 1 . 0 /‘ • es IN \ea 0. 5 ‘•■ 1 h•-.‘•._._.•-• 0.5 - \,,,.. y e- - .. r \VI 0. 0 _ •• 0.0

3-6" I.0 I. 0 3-6"

0. 5 0. 5

0.0 O.0

1.0

0. 5

0.0

0 C RY P TO ST I G MATA 1.5 AST IGMATA

o-Y I A' 1.0 0.5 0-3" BAs

0. 5 0.25 Af -•... 1 \ , O.0 0.0 \

I.0 0. 5

0. 5 0.25

0.0 0. 0

I. 0 0. 5 6-7.5"

0.5 0.25

0.0 s "; • -4 M J J A M J JASON 1969 1969

Fig. 23. Effect of aldicarb and'Zinophosi on Mesostigmata, Prostigmata, Cryptostigmata, Astigmata.

High. Field 1969. 101+.

INVERTEBRATES INSECTA & LARVAE OTHER /ARCRIMOTOINA *----+ Control • 0— --• Aldicarb A--.—• 1Z j nopho 1 Treatment —e 0. 5 . I. 0

\■11 0.25 0. 5 , • • *

0.0 0.0

D. 0. 5 3-6" Ix

(.90.25 0

0. 0

0. 5 6 —7.5" 1.0 6-7.5"

0.25 0.5

• -- 0.0 • • • -4 0 •■•• ■••••■• ■■•■ • A, 11 1 1 8 1 • M J J A S 0 N MJJASON 1969 1969

Fig. 24. Efieet of aldlOarb anelnoPhoSI On Inseota and Larvae, alid other RXXXVINNIA.Invertebrates High Fiela 1969. 105,

3. Comparative effects of sandy and clay soil on the persistence of aldicarb and'Zinophos'in relation to arthropod fauna of 0-6" soil_profile

Attempts were made to compare the persistence of

aldicarb and"iinophosl in the acid sandy soil of Church

Field and the alkaline clay soil of High Field. The

density of soil inhabiting animals should reflect variations

in the toxic residues in soil. Therefore, total mean

counts of arthropods extracted from treated plots for an

idential period for both insecticide wore compared with control counts up to 6 months after soil application. (Table 18).

The majority of Collembola, Acari and other

,n. C!LS A U1rJ ain-thrtrgad populations showed that carbamate and phosphorus

insecticides were more effective in sandy soil than in clay

soil. This may be attributed to the longer persistence of

insecticides in sandy soil. Chemical analysis of residues

of aldicarb metabolites (AppendixT.6) supports that the

rate of degradation was about twice as rapid in clay soil

as in sandy soil.

Pain and Skrentny (1969) determined the residue of

"iinophosi in the fields utilised for current extraction of

soil organisms by gas liquid chromotography. Eye-fitted

lines to the analytical data show that the organo-phosphorus

insecticides were three times more persistent in sandy soil

than in clay soil. Considering 0.05 ppm residue corresponding 106. Table: 18

Comparison of the mean population number per core between aldicarb and'iinophos'treated and untreated plots in Church Field and Hurley High Field from July to November 1969 (as percentage of control)

Mean Population in 0-6" Sandy Soil Clay Soil Aldicarb 'Zinophos' Aldicarb 'Zinopho

Collembola 69.7 44.9- 112.1 67.8 (2412) (174) Onychiurus sp. 12.7 3.6 41.7 50.0 (55) (12) T. krausbaueri 74.1 48.3 137.7 72.9 (2236) (122) Lepidocyrtus sp. 18.2 0.0 58.3 75.0 (22) (12) Isotomidae 14,1 1.1 (92) 57.1 (21) 57.1 Sminthuridae 0.0 0.0 25.0 0.0 (5) (4) Neelus minimus 0.0 '0.0 66.6 66.6 (2) (3) Acarina 36.9' 23.6 59.3 50.7 (292) (14o) Mesostigmata • 26.9 16.1 66.6 46.7 (223) (60) Cryptostigmata 0.0 0.0 13.3 26.7 (2) (30) ProstiEmata 75.4 44.3 73.9 63.0 (61) (46) Astigmata 33.3 100.0 125.0 150.0 (6) (4) Miscellaneous 30.7 51.3 66.1 50.0 (39) (62) Insecta 64.3 35.7 75.0 58.3 (14) (12) Othe InYt7:tbe.6..Tes 12.0 60.0 64.0 48.0 (25) (50)

Figures in brackets indicate mean total population in control. 107.

periods were 1 and 3 months for clay and sandy soils respectively. This concentration was about the L;50 obtained in bio-assays for T. krausbaueri (Table30a).f./S7

Data on the control populations (Table 18) indicate that the population of arthropods was significantly different in clay and sandy soil. Persistence of the liinophosl in sandy soil contributed to a greater decrease in the population. No doubt the drastic initial killing power of iiinophos and consequently slow population build-up of the species might have camourflaged the overall population difference in the course of 6 months. Rapid recovery after linophos treatment in clay soil, indicates rapid detoxification or the enhanced hydrolysis of the chemical.

T. krausbaueri constituted the major collembolan species in both soils but they were 18 times higher in sandy soil.

It seems evident that the population of Collembola was

10.8 x more than the gamasid predators in the sandy soil compared to 2.9 x more in the clay soil. Thus the less drastic overall effects of the chemicals in the clay soil was probably due more to their rapid degredations than to the absence of predators although their recovery was more rapid than in the sandy soil. Most of the Prostimata species extracted were predatory (4allwork, 1967) hence, a comparatively smaller decrease of these mites in ianophos' treated plots in clay soil than sandy soil might have occurred due to the initial population decrease of the predatory component of this group (Fig. 23 ). 108.

I nve Presence of higher number of other at -t hopeds might

have caused the higher migration of Astigmata (dallwork 1967),

in the aldicarb treated clay soil.

It seems obvious from the results that predatory

mites play an important role in regulating the collembolan

population after aldicarb troatment. Therefore, it was

considered worth-while to isolate various mites in families

or groups in future experimentation so that the re tion-

ships could be established more precisely.

4. Long - term effects of aldicarb and./Inophoss on the soil fauna of Church Field 1969-70 A census of the soil fauna in the top 9" of the soil was made in May, 1970, to investigate the effects of

aldicarb and'inophos'355 days after treatment. The

numbers of species extracted from the treated plots were

compared with those of untreated recoveries as a percentage

of a number in untreated plots. The species obtained

from 0-9" core were pooled into families/sub-order/order

to facilitate the evaluation of the long term effects of

pesticides on major groups of soil animals. Results

obtained were compared with the November, 1969 counts i.e.

6 months after application, (Table 19 ).

'Zinophos'affected all soil ang; "more drastically

than aldicarb. Collembola were less sensitive than Acari

to both insecticides on the basis of the 6 months and

12 months census; 350 per cent recoveries in Insecta were

calculated on the basis of only a few Coleopterus larvae, 109.

Table: 19

Long term effects of Aldicarb and iZinonhosi treatment on the soil organisms of sandy soil during 1969-1970, in 0-9" soil depth

% of number in untreated plots Aldicarb 'Zinophoss After After After After 6 months 12 months 6 months 12 months

Collembola 95.5 130.0 43.7 50.9 Onychiuridae 2.1 2.8 22.1 0.0 Tullberginae 103.0 146.9 47.0 63.6 Lepidocyrtidae 36.3 482.8 0.0 113.8 Isotomidae 2.7 101.8 0.8 1.8 Symphypleona 0.0 183.3 0.0 8.3 Acarina 12.7 23.9 4.7 8.4 Mesostigmata 5.4 8.0 3.7 1.9 Cryptostigmata 0.0 311.1 0.0 0.0 Prostigmata 58.0 48.8 12.6 22.4 Astigmata 5.3 254.5 0.0 0.0 Miscellaneous 29.0. 51.7 0.0 5.7 Insecta 350.0 26.6 0.0 16.7

Other invere b A 4.res 6.9 64.9 0.0 0.0 110. therefore, the figure may have little significance. Of

the true soil-dwellers (euedaphic) only T. krausbaueri

was able to recolonise successfully 6 months after the

aldicarb treatment. A rapid population build-up of

Collembola after 12 months for most species in aldicarb

treated plots appeared to be due to the absence of predators

and decrease in the toxicity of the chemical. It is

evident that aldicarb was more persistent up to 6 months.

It may be seen from the vertical distribution of Onychiuridae

(Fig. 12 ) that both insecticides affected the seasonal

maxima and, consequently, their population could not reach

normality and this may be the reason for the erratic

response seen (Table 19 ). Lepidocyrtidae out-numbered

the control population after 12 months of"Zinophos' treatment,

otherwise the populations of all other invertebrates

examined remained greatly reduced. T. krausbaueri could

be considered as a comparatively less susceptible species

of springtails toiiinophos: 5. Vertical distribution of subterranean micro-arthropods So far only soil samples up to a12" core have been

considered and it was observed that the numbers of most

subterranean species were significantly different in lower

depths. Previous attempts by Scopes (1965) and Maddieon (1969) were limited to 4" depth in arable land used for

the present studies. Therefore, some efforts were made to

investigate the depth distribution of major subterraneous

Collembola, Acari and other arthropods.

November, 1969, and April, 1970, were convenient

periods and soil samples were taken up to 15" and 21" depths

respectively. Population densities observed have been

recorded as mean values (log x 1) taken from 10 samples

(Fig. 25). The differences in the population counts were

most likely due to seasonal fluctuation, differential

mortalities, and aggregation tendencies of individuals.

It is evident (Pig. 25 ) that Collembola, Acari and other

arthropods were available in deeper soil layers, perhaps

due to the availability of sufficient travelling routes

(pore spaces) occurring in the cultivated sandy soil.

The density of T. krausbaueri and I. productus were

significantly decreased after 18", and similar indications

were available for the other arthropods. The changes in

the population correspond to the status and composition of

species quoted earlier for other depths of samples(T. 20, 21)

HaarlOv (1955) found arthropods up to 20" and reported

that the distribution of Collembola and mites was correlated Fig. 25. The vertical distribution of subterranean

micro-arthropods in November 1969 and April 1970 at various depths. 1. T. kraUsbaueri

2. OnyChtm,:.Us . Folsomia T. prodUctus'

5. Mesostigmata

6. Proetigmata_ 7. Astigmatn, Inver. b 0.. re/ .8. Other ,Aot4roposie..- APRIL 1970 NOVEMBER 1969

CTO to IN " 0 /A 0 I I II C.fl, aF3 a go= 0% LJ III II 1 I I I I 1 I I I I _F

0 r 0 0 0 as lA xl co

'241, 113.

Table: 20

The mean number of invertebratesin 0-15" cores in untreated plots in Church Field in November 1969 at various depths

0 _ 311 3 _ 6" 6 - 9" 9 - 12" 12 - 15"

COLLEMBOLA Onychiurus sp. 12.8 0.8 . 0.0 0.0 0.0 T. krausbaueri 288.9 179.2 73.8 46.5 10.3 Folsomia sp. 0.5 0.1 0.4 0.0 0.0 I. productus 4.3 7.8 8.3 7.7 4:6 ACARI Mesostigmata 50.9 21.7 9.3 4.0 . 2.1 Prostigmata 10.1 1.0 3.2 4.1 0.8 Astigmata 4.6 0.8 0.3 0.4 • 0.0

Other inverebitare4 2.8 0.1 0.2 0.5 0.0 114. Table

The mean number of invertibratesin 0-21" cores in untreated plots in Church Field in April 1970 at various depths

0-3" 3-6" 6 19" 9-12" 12-15" 15-18" 18-21"

COLLEMBOLA

Onychiurus sp. 5.0 0.0 0.0 0.0 0.0 0.0 0.0

T. krausbaueri 74.6 90.7 23.0 9.4 5.7 8.8 0.6

Folsomia sp. 1.0 2.2 3.5 0.7 0.3 0.3 0.3

I. productus 6.o 5.5 13.1 15.3 15.8 7.9 0.6 ACARI

Mesostigmata 1.8 0.7 2.6 0.8 3.5 1.8 0.0

Prostigmata 4.6 2.2 2.8 2.4 2.9 4.1 0.0

Astigmata 0.2 0.1 0.2 0.2 1.0 0.0 0.2

Other Ins eta 44:tes 0.8 1.4 0.8 3.0 1.4 5.0 0.1 115„ with the availability of food. Madge (1965) found that climatic conditions and organic material caused variations in population densities of mites and Collembola extracted from 5.5" soil depth. Glasgow (1939) and Baweja (1939) have studied vertical distribution of some insects up to

16" and 33" respectively, hut, due to different methods of extractions and soil types, results cannot be compared.

One other factor which could contribute to variation in the vertical distribution of Collembola is the density of the soil. Increase in the bulk density (mass of soil/ unit volume) of a particular soil leads to decrease in its porosity or in the fraction of the soil volume which can be occupied by water or air. Murphy (1955) and Klima (1956) have considered microarthropods in relation to soil structure, and have shown that the highest densities occur where the pore spaces are largest. According to HaarlAv (1955) the cavity size decreases with depth in mineral soils a.d showed high densities of arthropods in the upper layers of soil.

Clearly the number of T, krausbaueri per sample is related to the bulk density of the soil (Table22 ). The bulk density increases with depth of sampling and numbers show a corresponding decrease. This association is emphasised when considering the variation in bulk densities of soil from the same depth and the numbers of T. krausbaueri extracted from them (Table 23 ). 116.

Table: 22

Comparison of the bulk density of cores of different depths for the yield of T. krausbaueri from sandy soil in November 1969

Depth No. of individual Mean Bulk density* in in samples in samples inches 1 2 3 1 2 3 0 - 3 240 145 91 1.98 2.24 2.62 3 - 6 278 167 17 1.86 1.94 3.05 6 - 9 104 155 64 2.34 2.49 2.80 9 -12 15 17 7 3.09 2.95 3.32

* Mean of 2 replicates for each sample 117.

Table: 23

Comparison of the bulk density of different depths of one sample for the yield of T. krausbaueri from sandy soil in April 1970

Depth in inches No. of individuals Mean bulk* in the sample density

0 - 3 196 1.21 3 - 6 131 1.60

6 - 9 10 2.09 9 - 12 6o 2.37 12,- 15 10 3.14 15 - 18 2 3.72

* Mean of 3 replicates for each depth . 118.

6. DISCUSSION More intensive studies on the persistence of aldicarb and'iinophoss t-hari-during 1968 and 1969 confirmed that the latter insecticide affected soil arthropods drastically and recoveries in most of the Collembola could not approach control levels after 12 months of treatment during 1969-70, and after 8 months during 1968-69 trials. Results obtained during January 1968-69 (Fig. 8 ), were broadly comparable to the findings reported in Tablel9 for 1969-70. Minor differences are probably due to sampling after 3-4 weeks of snow during January, 1969. Latzel (1907) and

Kiihnelt (1961) have already recorded the influences of frozen soil on the various species of Collembola,

Chemically it was established that aldicarb was much more persistent in soil at 10 ppm dose level (AppendixT) than'iinophod (Pain and Skrentny, 1969). Scopes (1965) has reported drastic effects of zinophos on T. krasubaueri,

Onychiurus sp, and Isotomurus palustris. Therefore, the severe effect of.7inophos'seems to be only due to its initial destructive power of the soil organisms. Aldicarb

(Metcalf et. al., 1966) and organophosphort insecticides are cholinestrase inhibitors and this appears to be their basic mode of action, O'Brien '1967 ,O'Brien & Yamamoto (1970). In view of the conversion of DDT to DDB in F. candida

(Butcher et. al. 1969) it may be suspected that aldicarb ) might be detoxified sulphoxide (SO) and sulphone (SO2 119. to non-toxic metabolites by Collembola. Moreover, the higher rate of oxygen consumption in Mesostigmata predatory mites than in non-predatory forms, Webb (1971) suggests that a secondary reason for the increase in population of the former might be associated with their higher oxidative metabolism which could play a role in the detoxification of toxic metabolites of aldicarb. Therefore, some bio-chemical investigations may be suggested, in view of the increased population build-up in aldicarb treated plots observed during the 3 years census of the present study.

Voronova (1968) has studied the effect of Sevin (carbamate) and Malathion (organophosphorus insecticide) but his findings were mainly limited to soil-dwelling animals such as beetles and earthworms. Griffiths and Bardner (1964) used organophosphorus and carbamate insecticides as soil treatment for the control of wireworms. They found that two carbamates namely Sevin and Isolan, were not as persistent as organophosphorus compounds such as iinophosi in laboratory experiments. They found that'/inophod was persistent up to 259 days. Edwards et. al. (1968) have published a detailed account of Chlorfenvinphos (organophosphorus insecticide) and reported a different pattern of change in the soil fauna than that observed in present findings. Therefore, it may be suggested that different insecticide exert different effects on the soil fauna.

The effects of carbamate are not comparative with the effects of chlorinated hydrocarbon and eyclodine group of insecticides extensively studied at Rothamsted, Experimental

Station (Edwards, et. al., 1967). 120.

The effect of various soil characteristics on the

chlorinated hydrocarbons have been studied by Wheatley et. al.

(1962), Lichtenstein and Schulz (1959, 1961), Edwards (1966)

and factors affecting persistence of pesticides in soil

have been described by Edwards (1964, 1966, 1970). Similarly

Scopes (1965), Getzin and Rosefield (1966), Way and Scopes

(1968) and Pain and Skrentny (1969) have reported

factors associated with the persistence oelinophosa in soil.

Earlier, Edwards (1966) pointed out that organo-

phosphorus insecticides persist longer in acid soils than

alkaline ,3011. He further mentioned that chemical structure

of the compound, intrinsic stability, volatility, is an

important factor of the persistence, and the effectiveness

is inversely proportional to its water solubility.

Therefore, in view of the chemical properties of aldicarb

and'inophos% it may be suggested that the persistence of

the latter will be more affected by rainfall.

Major studies on the persistence of aldicarb and

"Zinophos were concentrated for 6 months after insecticidal

application. Skrentny (1969) reported 0.25 ppm residues

of aldicarb-sulphoxide and sulphone in the sandy-loam soil

and 0.03 ppm in the olay soil (0-6" depth), used for

extracting soil fauna; quantities of aldicarb were higher

in the 6-12" layers (AppendixT.6).

Differences in the pH of clay and sandy soils may be

considered as one of the vital variables affecting the

differences in persistence of a7inophos. Getzin (1968)

stated that the effect of soil pH upon insecticide 121. breakdown is a complex phenomenon, involving interactions

between pH and hydrolysis of the insecticides, absorption, and microbial activity.

Pain and Skrentny (1969) published information on the soil characteristics of High Field (clay) and Church Field

(sandy) soils. Major diferences were found in the clay content (5.1 in sandy and 24.7 in clay), fine- sand (49.3 in sandy and 27.9 in clay) and pH values determined by the

present author were 5.8 in sandy and 7,5 in clay soils.

Present studies suggest that the pH of the soil plays some role in the alkaline hydrolysis. Lichtenstein and Schulz

(1964) and Getzin (1967) have demonstrated that breakdown

was faster in more alkaline soil in the case of organo-

phosphorus insecticides and Griffiths et. al., (1967) have

mentioned similar influence of the pH on the persistence

of ilnophos.

The initial drastic effect ofilinophos on athrapoilL6

may be due to its dual mode of action namely respiratory

poison (see table of physical-chemical properties i.e.

Table25) besides contact action. Aldicarb has a low

vapour pressure and does not have a significant fumigant

action. Factors affecting persistence of soil-applied insecti-

cides have been discussed recently by Edwards (1970). Some

workers (Abdellatif, 1967; Clark, 1967; Coppedga et. al.,

1967; Hendrickson and Meader, 1963; Bull, 1968;

Skrentny, 1970) have reported various factors affecting

the persistence of aldicarb in soil and demonstrated its

effects on the biological activity in different ways. 122.

Skrentny (1970) noted a difference in the microbial activity of the sandy and clay soils which he listed as a possible factor the doal.tAdation of eldi.carb in soil. But in view of Getzin's findings, it appears more important that the microbiological activity was playing a role in the comparative persistence of'/Inophod in the two different soils studied.

Pain and Skrentny (1969) determined by GLC the residue of/inophos in both soil types in the field. One year after application, it was found present in detectable quantities

(0.025 ppm in 0-6" layer, 0.028 ppm in 6-12" layer and not detectable in 12-18" layer at Church Field but no residues were found in any layer at High Field). It may be seen that traces oflinophod were extremely doubtful after 12 months.

However, small quantities of'Yinophog may prove sub-lethal to some species. Values for LC1 and LC10 calculated from the regression/equations of i'Zinophoss (Table 30*) gi7es

0.0014 ppm and 0.0063 concentration respectively. Such low concentration are difficult to detect by GLC method of

Pain and Skrentny (1969). Scopes (1965) showed that Folsomia spp. were sensitive to 0.003 ppm oflinophoss and he found higher residues than this in treated fields 760 days after treatment for application rates close to that used in the present studies. Such a result suggested that there are possibilities thatlinophos' was persistent in the field in quantities and may be toxic to the soil organisms extracted. 123.

14 Getzin and Rosefield (1966) using C labelled chemicals reported that the half-life of 1 2inophos was six weeks in sandy loam soil and Getzin (1968) reported that the micro-organism and non-biological factors affect the persistence of organophosphorus insecticide in Sultan silt loam. For example diazinon was primarily degraded through non-biological pathways. In contrast micro-organisms degraded 30e70% of.iinephos, depending upon the environmental condition.

Aldicarb was detected after twelve months (Skrentny,

1970) (Appendix T. 6). It is therefore obvious that toxic residues of pesticides were present in the field up to one year after their application. Moreover, quantities of pesticides predicted from the above findings may prove toxic to Collembola on the basis of bio-assays performed during the present investigation. These suggestions indicate that residues of pesticides were present, although in small quantities, when the 1969 experiments were carried out after 1968 trials. It might have led to some cumulative effects of poison on the soil fauna. 124.

Present studies help to elucidate the effect of

1 4 V eYeblittfeC aldicarb and Iinophos on the ai41.traTrod fauna of clay and

sandy loam soil types.

Studies carried out on the persistence of aldicarb

andi7inophos (1968-69) in sandy and clay soils were a

preliminary assessment during the development phase of

extraction techniques. Comparison with the findings of

other workers shows that Scopes (1965), for example

obtained similar response of Collembola to'iinophos'but the response of Acari was different from Scopes's findings.

Differences in the susceptibility of Collembola and Acari

have already been documented by Edwards (1965), he did

not investigate the effects of the recently introduced

carbamate, aldicarb, used in present studies. Due to the

broad spectrum and non-selective actions of aldicarb and iiinophos, fauna were grouped into Collembola, Acari, and

other arthropods. Clay soil proved to be less effective

for maintaining the persistence of pesticides. A remark-

able change in the population balance of prey and predatory

groups was noticed in both sandy and clay soil after

application of aldicarb and zinophos.

Persistence of both pesticides was detectable up to 6 months after treatment by the low yields of Collembola and Acari but the response was mixed in other insects and

other arthropods. The high susceptibility of Collembola

to organophosphorus insecticides has been pointed out by

Edwards (1965), and Scopes (1965). Effects oflinophos'

were in close agreement with those of chlorfonvinphos 125.

recorded by Edwards et. al., (1968). Aldicarb did not

completely destroy populations of Collembola nor mites in

either of the soils studied. Stegeman (1964) found a

similar reduction for forest soil mites and Collembola

after carbaryl treatment. Voronova (1968) used emulsion/

suspension and dust formulations of sevin and malathion

on forest soils and observed much faster recovery and less

drastic effects of pesticides than was found by Edwards

(1966) who concluded that granules are more effective

and persistent than other formulations.

Tullberginae showed little effects of carbamate and

phosphorus insecticides in both soil types. Maddison (1969)

recorded similar effects on T. krausbaueri of zinophos

treatment. Onychiuridae were affected, but the effects in sandy

soil were less definite with aldicarb and in clay soil

treatment with'Zinophos. Edwards et. al., (1968) mentioned

that chlorfenvinphos, a phosphorus insecticide, showed

less definite effects to species belonging to the

Onychiuridae. Lepidocertidae were much adversely affected

in sandy soil after treatment Zlnophos'possibly because

of the surface activity of insects and the fumigant action

of iZinophos% Responses of Isotomidae were similar to

Lepidocridae except Folsomia spp., appeared less affected. Findings of Scope: (1965) and Maddisori (1969) on

the effect of low rate applications oelinophos to the soil

fauna are comparable to p:sesent studies. Many differences 126. were observed in Symphypleona from Maddison's findings because Sminthuridae and Neelidae when separated in the present investigation showed considerable differences in their susceptibilities, which most likely due to their habitant differences. Some changes in the density of mites might have occurred during maxima and minima because of their migration.

Aldicarb proved more injurious to predatory mites

(Gamasina) in clay soil than in sandy soil. 'Zinophoss was less effective to mites in clay soil and recoveries were more definite but changes in their bioecology influence their overall existence in both soil types. Some non- predatory groups of Cryptostigmata were completely destroyed in sandy soil which might suggest the persistence of high populations of predatory mites. It has been reported by

Karg, (1961), that Gamasina prey on the juveniles of

Cryptostigmata. Increases in the Astigmata were considered

C to be due to the high number of other arApee4e. in clay soil, which might help the migration of these saprophagous mites.

Edwards (1969) reported that enchytraeids were unaffected by many different kinds of soil-applied insecticides. He mentioned further that most of the families of springtails, excluding Isotomidae and all Symphylids, have considerable immunity to many insecticide (organophosphorus and Chlorinated hydrocarbons) and that earthworms and enchytraeids were also unaffected, but the carbamate sevin was reported to be effective against enchytraeids (Voronova, 1968) and the present author observed a similar response to aldicarb. 127.

A general observation of the dominant weeds which were present in sandy and clay soils suggested that

.21nophosi waB more phytotoxic than aldicarb (Appendix 8, 9). The density of weeds, by the beginning of autumn, was increased in aldicarb treated plots more than the control, whileeZinophos'treated plot had sparse flora. No significant difference was recorded during the next

growing season in the aldicarb treated plot, and plants in • 4 3anophos treated plots remained slightly less than in the

control. Increase in the weed density of aldicarb treated plots might be due to the destruction of fauna resulting in an increase of nitrogen resources in the soil.

Naglitsch and Steinbrenner (1963); Ryke (1965) and Maddison (1969) reported that fluctuations in the soil fauna influence the density and variety of flora. Thus a combination of the effects of the direct influence

of the chemicals on the flora and the indirect effect through modifying soil fauna numbers and species composition may be suggested. It would appear also that the microflora

have a striking qualitative and quantitative effect on the Collembola population (Jahn, 1960; Knight, 1961; El-kifl, 1959). No attempts were made to investigate the

specific contribution of flora to the fluctuations in

the fauna. 128.

S;CTION III.

TH6 SUW3PTIBMTY OF COLLEMBOLA TO ALDICARB .ANDI ZINOPHOSI .ig.ZCYICID2S IN THE LABORATORY AND BIOASSAY OF INSECTICIDE TTgfflfs—frflif. s

Attempts were made to investigate the long-term effect and persistence of aldicarb in the soil by bio-assay using Collembola in the laboratory, Folsomia fimetaria adults and larvae were selected, and their susceptibility to soil extracts from aldicarb treated plots using a filter paper bio-assay technique. Effects of such treated soil were investigated qualitatively on the life stages of the species to evaluate the broad spectrum long-term effects of the pesticides on the fecundity and general behaviour of the insect.

It was also considered worth-while to compare bio- assays, based on soil extracts, with others on the pure insecticides, because the analytical methods for residue

determination were specific to aldicarb, and two Lits

metabolites, namely sulphoxide and sulphone, and/not rule

out possibilities of the presence of other unknown toxic

metabolites of aldicarb.

The effects of unknown toxic metabolites were in-

directly assessed by using an extract from three weeks-old

aldicarb treated soil, and soil itself. Information on

the susceptibility of F. fimetaria was also obtained by

using insecticide treated soil containing 3.9 ppm

chemically estimated aldicarb sulphoxide and thoroughly

mixing it with untreated pulverised soil to decrease the

level of toxicant for a satisfactory mortality response. 129.

Residuos of Odiosrb in soil were estimated by a semi-

quantitative thin layer chromatographic technique as

described by Skrentny (1970).

Beard (1949) emphasised the significance of time

of evaluation and the dosage - response curve. He mentioned

that the killing dose and time required to kill are not

mutually independent. A low dose of a toxicant, acting

for a long time, may be as effective as a high dose acting

for a short time. Unfortunately these considerations were realised only at the end of the bio-assays and it was

thought useful to draw a time-mortality response curve

for Tullbergia krausbaueri treated with aldicarb and

"iinophos

The three species used were T. krausbaueri, F. candida

and Folsomia fimetaria.

1. Materials and Methods (A) Culturing Methods

Many soil mites and Collembola feed on verticillium

soil fungi, spore heads and distal parts of conidiphores

(Sewell, 1959). Witkamp in (1960), estimated that under

favourable conditions Onychiurus armatus can eat 6 metres

per day of hyphae of mycelium of Mortierella pusilla

variety Isabellina. It has been reported that the same

insect can even digest spores if their cases are damaged.

Poole (1957), showed that fungi may remain viable

after passing through the gut of the Collembola and he

concluded in (1959), from gut analysis, that smaller species

of Collembola appeared to feed on the humus, whereas the 130. larger species of Collembola fed mainly on soil fungi.

Christianson (1964) reported that most forms of Collembola feed on both decayed and undecayed plant materials, fungi, and bacteria.

Several workers have attempted to determine the food of Collembola species more precisely by analysis of gut contents. Healey (1970), classified the gut contents of soil and litter-dwelling Collembola as follows:- plant material, fungal hyphae, fungal spores, pollen grains, collembolan remains (setae, cast skins, scales, etc.), other arthropods remains, enchytraeid setae, mineral particles, and other materials.

Such gut content materials were found in four species of Onychiurus and two species of Tomecerus, Healey also reported that so far almost nothing is known of the physiology of digestion in Collembola. Edwards (1962) reported that Onychiurus hortensis (Gisin) feed on bean seedlings.

It was reported by Mills and Sinha (1971) that out of 43 fungi and actinomycetres tested, Alternaria alternata (Fries) Keissler, Cladosporium cladosporioides

(Fresenius) De Vries, Bipolaris tetramera (McKinney)

Shoemaker, and Sporotrichum carnis Brooks and Hansford were the most favourable diets for Hypogastrura tullbergi.

Yeast is still used in the laboratory as the most successful diet for some species of Collembola (Christiansen 1964).

Peterson (1970) was successful in culturing T. krausbaucri by adding a yeast of Candida sp., which was isolated from 131. wood soil and cultured on an agar plate, but it was thought that an even bettor rr7tural die*. for T. krausbaueri could poscibly be found.

The size of aggregations has been reported to be often greater than 12" in diameter (Glasgow 1939). It was therefore decided to make soil extracts from sample units, which were taken adjacent to samples which had yielded a large number of T. krausbaueri. In this way it was thought more likely that a suitable and acceptable extract would be obtained and used as a satisfactory diet for this species.

Soil samples were taken by an auger to a depth of 12" and animals were extracted using a high gradient cylinder

(Nacfadyen 1961). The procedure was to take the soil

(with roots when present) and gently crumble it in a

100 ml beaker. After removing stones and any other alien objects, 20 grams of the soil were added to a plastic dish containing distilled water. The muddy mixture was stirred in order to separate the soil particles, and left for a while so that the organic matter such as humus and animals could float to the surface, and the inorganic matter sink to the bottom. This suspension was examined under a binocular microscope, all living and dead animal specimens were removed, and the suspension then poured through a sieve (30 mesh) which rested over another sieve (of 60 mesh). This sieve in turn rested above a third sieve (of 100 mesh) made of bolting silk, which itself fitted into a Petri dish. The silk was dyed black 132 with IndiAn ink for orine in examining the retained material.

The contents of the two upper sieves were checked and washed carefully with distilled water into a sterile bottle, the contents of the third sieve were also examined and washed into another sterilised bottle. The suspension in the Petri dish was refiltered and washed into a third bottle; these bottles were kept at a constant temperature of 25°C. for a few days before use for moistening the culture vessels.

A method of culturing similar to that described by

Goto (1961) was used. Four ounce, wide-mouth jars of internal diameter 5.2 cm. and length 7.5 cm. were used for the vivaria. A ratio of nine parts Plaster of Paris to one of activated charcoal was mixed well, and placed dry in the vessels to a depth of approximately 1 cm. The

necessary water was then added and, whilst stirring, a

little extra charcoal was added to provide a better coloured

background for visual examination, and also to provide an

indication of the moisture content of the Plaster of Paris.

When the plaster had set, the insides of the vessels were

cleaned. The surface of the plaster bed was smoothed and

allowed to harden and left until nearly dry; these vivaria

were sterilised by means of a small gas jet flame. The

clean smooth plaster surface is ideal for observation of

the eggs and all instars under a binocular microscope.

Ten millilitres of distilled water were then poured into

each jar and was all absorbed quickly. The bed was then

moistened in one area by the addition of soil extract 133. solution from the third bottle and kept at/or near satura-

tion point, but not with oxccso surface water which was carefully removed with a piece of absorbent tissue.

Floating matter from the second bottle was removed with a fine squirrel-hair brush size No. 3 and placed in another area of the vivarium, and this procedure was repeated with larger materials from the first bottle. Before closing, the cardboard disc inside the screw-top was moistened to

maintain desirably humid conditions. The vessels were

closed tightly with screw-on tops to reduce evaporation

from the plaster.

The culture was examined periodically at intervals in

the region of one week to ten days. When some fungal

growth was observed the Tullbergia adults and other

Collembola species were introduced to the jars. It was

noticed that Tullbergia krausbaueri fed on certain fungal

species. A fresh soil extract was used for wetting the

old culture. No special aeration was necessary since the

exchange of gasses when the vivarium was opened for

periodic examination was sufficient to sustain the

Tullbergia or other species.

The cultures and all treatments were held in a small

incubator with the temperature controlled thermostatically

at 25°C. + 0.5°C. Water in pyrex dishes inside the

incubator maintained the atmospheric relative humidity at

about 70% + 10%.

The fungal species which were present in these

cultural jars were identified. The organisms have been 134 identified in the Plant Pathology Department at Imperial

College Field Station as follows:-

Culture 1. mixture of Pythuim sp. and Cephalosporium sp

Culture 2. possibly another species of Trichoderma Culture 3. Trichoderma viride

Culture 4. Mflcorhceous fungus, probably Mucor 5. PenicillivA sp. Culture 6, Fusarium, probably F. culmorum

Culture 7. Trichoderma viride

Culture 8. same as 4, but mixed with a Penicillium sp.

Similar pure cultures of the above identified cultures were identified by the Commonwealth Mycological Institute as follows:-

1. Fusarium solani (Mart.) Sacc. Penicillium sp.

2. Trichoderma koningii Oudemans

3. Penicillium lil-lcinum Thom. Trichoderma sp.

4. Mucor SD Fusarium solani (Mart.) Sacc.

5. Penicillium sp. Trichoderma sp.

6. Fusarium culmorum (W.G.sm.) Sacc. Nucor sp.

7. Gliocladium deliquescens Sopp

8. Mucor sp. Fusarium solani (Mart.) Sacc.

Later on, in routine culturing it was observed that the abundance of mucoraceous fungus (Mucor sp.) favoured the breeding of T. krausbaucri. Folsomia sp. showed a similar response in the presence of Penicillium sp. and

Fusarium culmorum. Therefore, there were indications of feeding specificity in the species of Collembola used later in bio-assay. The other two species Onychiurus trinotatus and Neelus minumus were bred in other culturing jars in 135. which there was little fungal growth and which was apparently

Unnocossary for their development. No attempt has been made to specify the favourable fungus for their food choice. Preliminary attempts have been made to examine the gut contents viewed through the gut wall under a microscope of certain Collembola sampled from the field or from laboratory bred cultures. These specimens were mounted in

Goto's modification of polyvinyl. Such information is however, limited in its value considering the diet of these species since identification depended on shape and colour of food particles:

1. Onychiurus trinotatus - Fungal mycelia, part from

their own exuvia (spine), spores possibly.

2. Tullbergia krausbaueri micro-organisms or fungal

mycelia (which grew on mixture of Plaster of

Paris and charcoal in laboratory culture),

faecal materials, Unicellular algae or possibly

humus.

3. Folsomia fimetaria and Folsomia candida. Fungal

hyphae, micro-organisms, possibly spores and

faecal materials.

4. Neelus mintmus Micro-organisms (grew on the

Plaster of Paris culture).

5. Tomocerus minor and Tomocerus flavescens.

Decaying leaves, pollen grains, spores.

These observations draw attention to the suggestion that some Collembola species are not at all fastidious in their choice of food. Some Collembola species show no 136.

pnrticulal- Fvoferonao to a cortain diet, and, in fact,

the contrary seems to be true (Agrell 1941). No attempt

has been made to analyse the gut contents of these materials,

due to the limited resources which have so far been developed

for this purpose. Although it has been widely reported

that fungi form one of the food constituents of collembolan

diets, to my knowledge host specificity has not been

reported previously, Moreover, present evidence supports

that the fungi is an essential part of the diet. Some

more studies in this direction may reveal further food

preferences and lead to improvements in laboratory rear-

ing diets, compared with the conventional use of yeast

(Christiansen, 1964; Butcher et al. 1971).

It is certain that species vary greatly in the

selection of types of fungi that can and will be eaten.

(b) Age determination in Collembola

For bio-assay work it is important to use individuals

of known age. However, age determination is difficult

and two alternative methods of rearing insects of known

age were used. 1. Many Collembola, for example Folsomia sp., lay

their eggs in batches. When these species began laying

eggs they were placed in a fresh culture jar. After a

set time interval, 24-72 hours, these were removed and

the new culture used as a source of insects for the bio-

assays.

T. krausbaueri, however, lay their eggs scattered

over the culture, for example on the mucor fungus growing 137. jn tho bod of the vivarium and the crevices and holes in the planter substrate, and el.•o difficult to collect in sufficient numbers.

2. The method favoured for T. krausbaueri was to use the criterion that when individuals lay egg batches they have reached the 7-8 instar period of development (Hale, 1965).

In an attempt to limit the laying area small plastic vials with attached lids having a hole were inserted into the culturing jars filled with a layer of the previously used cementing materials and having only a 5 mm. cavity at the top, Adults did lay their egg batches in these cavities and it was a simple matter to observe adults when they laid the eggs. The method was found successful for observation on the life stages and predators but for the purpose of setting up sub-cultures tha method was found time consuming.

This culturing method may also prove valuable in future work on the life-cycles of ecologically important species, if a comprehensive analysis of the kinds of food consumed by any single species under widely varied condition can be predicted.

The sources and food of the three species used in the bio-assays are listed in Table 24.

138.

Table: 24

Source and food of the species used in toxicolyical studies

Species Food Source

T. krausbaueri Soil extract Lower Church Field,

(soil fungus mainly Silwood Park Hucor sp)

. fimetaria Soil extract Lower Church Field, (soil fungus mainly Silwood Park Penicillium sp. Fusarium culmorum)

F. candida Yeast pellet Pure strain from the insectory of Imperial College

For F. candida and F. fimetaria the laboratory bio-

assays were carried out in wide-mouth jars, and specimen

tubes (2 cm. by - 2 cm.) were used for T. krausbaueri.

A circular filter paper (Whatman No. 1) with the same

diameter as the container, was placed on the bottom of

the jar, and smoothed with a glass rod to ensure close

contact with the bottom, thus preventing individuals

crawling underneath, a filter paper was also placed in the

bottom of the tube. Similar containers were used for bio-

assay tests employing treated soil.

The effects of pesticide residues in soil on life

stages of F. fimetaria was carried out in the laboratory

by keeping contaminated soil and insects in 100 ml. plastic

containers (5 cm. diameter and 5 cm. deep) with a tight

fitted lid. 139.

(a) Insecticides

Pure chemicals and stock solutions were kept in a deep- freeze at - 20°C. Pure insecticides were dissolved in redistilled analytical grade acetone and diluted to the required concentrations. Pure samples of aldicarb /'2-Methyl-2- (methylthio)f-propionaldehyde 0-(methylcarbamoyl) oxime7, (TemikR) (registered trademark for Union Carbide 21149) and two

potential metabolites of aldicarb sulphoxide, (2-methyl-2- (methylsulfinyl) propionaldehyde 0-(methylcarbamoyl) oxime7 and aldicarb sulphone L 2-methyl-2-(methylsulfonyl) propionaldehyde 0-(methylcarbamoyl) oxime 7, were supplied by the Union Carbide Corporation of U.S.A. R N Thionazin (Zinophos ) Diethyl 0-2-pyrazinyl phosphorothioate was supplied by the Cyanamid of (Great

Britain) Ltd. The information on the solubility and vapour pressure of insecticides are listed in Table 25. 140.

Table: 25

infol-mation on the solubility and vapour pressure of insecticides

Insecticides Solubility Vapour Pressure

Water ',Other Solvents

Aldicarb (Temik(R)) 0.6% (Soluble in most Less than !organic 0.05mm at 20°C. !Solvents but Aldicarb sulphoxide 33.0% 1.xlsoluble tieptane

Aldicarb sulphon.e at 0.7% 20°C. -1--1 Thionazin at 0.1144 Misicible 3 x 10 -3mraHg. with most at 30°C. (Zinophos(R)) 24.8°C.1 organic solvents

* Data from Skrentny (1970) and Martin (1971)

Note:

Aldicarb, is an approved name by the Committee on

Insecticide Terminology of the Entomological Society of

America and by the British Standards Institution (BSI);

Zinophos is approved by the (ESA) and Thionazin is

only approved by the (BSI) Rev. Appl. Ent. A., 59.

1 and 12 (1971). (H) Methods of Treatment

(1) Filter .parer method

A circle ( 2 cm. diameter) was drawn, with pencil in

the centre of the filter paper, and connected to the

periphery to split the remaining area into two parts, to

facilitate insect-counts in the bioassay tests. Filter

paper used in jars/tubes was treated with the insecticide

by applying the desired concentration in 1. ml. of solvent

(acetone) using a 1, ml. glass syringe and despensing the

liquid spirally from centre to periphery to ensure a

uniform deposit. Filter papers were treated with acetone

for control. After the acetone had been evaporated from

the containers, in a fume-hood, 1. ml. of distilled water

was pipetted onto the filter paper in jars and 0.1 ml in

tubes. These quantities of water were considered optimum

for wetting the entire area of the filter paper. The lid

of the jar or the cork of the specimen/tube was soaked in

water and placed tightly to maintain the internal humidity.

Specimen tubes were kept in a Petri dish (14 cm. in

diameter) having a 5 mm.. water layer to maintain the

moisture of the corks. Care was taken to wet the lid and

the cork whenever insects were observed. After treatment,

containers with insects were held in a cabinet maintained

at a temperature and humidity as described under the rear-

ing method. Mortality Counts were taken periodically as

indicated in the results shown. There were three replicates

for each dose level. This method was used in two ways:-

(a) using pure chemical (Tables 26-30)

(b) and soil extracts (Tables 34, 35) 11+2.

(ii) Soil treatment method T. krausbaueri

Soil samples were taken with an auger from the untreated areas of Church Field. In preliminary experiments it was

observed that control mortalities in test insects placed

on soil samples from 0-3" and 3-6" layers were considerably

higher than in those from 6-12". Although the precise

cause of those differences are not known the high control

mortalities were thought to be possibly due to unknown toxi-

cants produced by microbial activity, therefore, the 6-12"

samples were considered suitable for the test. This layer

has the additional merit of being a mineral type, which

contained homogeneus soil particles and was more likely to

give a uniform deposit of insecticides which is a vital

factor for the assessment of the toxicity.

Samples taken at random were pooled and throughly

mixed. The air-dried soil was passed through a 100 mesh

bolting silk sieve. 1 gm. of the soil and 1 ml. of

distilled water was pipetted into each specimen tube and

after gentle mixing of soil and water, the tubes were kept

in an oven fitted with a blower at 120-140°C. for 20

minutes to evaporate the water; a smooth hard layer was

formed during the drying process. When tubes had cooled,

the pure insecticides dissolved in 1 ml. acetone was

pipetted onto a soil uniformly, and tubes were kept under

fl f hood to evaporate the solvent. For control, soil

was treated only with acetone. Approximately 0.7 ml. of

distilled water was added to moisten uniformly the soil in

the bottom of tho tube. 143.

The method of handling for Folsomia spp. and T. krausbaueri was different, due to their different size and activity. For Folsomia sp., insects of known age group (28 + 3 days) were transferred from the original culture jars to a moist and clean jar and were finally transferred into jars containing treated filter papers for bio-assays. For T. krausbaueri water was added to the cultures just to float them off the substrate and it was observed that they aggregated at the periphera, probably because of water-surface tension. It was then easy to separate large numbers of insects in a short time using only 3 hairs of a squirrel hair brush (size No. 3) and transfer them from culture jars to eye cells (1.5 cm. - diameter and 5 mm. depth) drilled into a perspex sheet

(Fig. 26). The insects, being white in colour, could be

easily seen against a dark background provided by painting

black the outside base of the cells. T. krausbaueri

used were adults of 7-8 instars, using the egg batch

criterion.

Isolated insects from culture jars were kept in

distilled water for 24 hours before they were released

for the toxicity determination. Handling, and making

initial counts and mortality counts of insects were carried

out under a binocular microscope at x 5 or x 10 magnifica-

tion. Insects found damaged or dead were discarded before

the toxicant-response was measured.

The insects were collected, transferred into treated

specimen tubes in the same way as for filter paper treatment.

There were 3 replicates for each dose. Fig.26. Eye cells (Covered) drilled into perspex sheet. 145.

F. fimetaria

The soil wars sampled from the treated and untreated areas set up in May 1970. The procedure for biologically assaying toxicants in treated sells were as .follows:- (a) Soil from the untreated areas was 'cleaned° using acetone.

(b) Soil was collected from the aldicarb - treated areas three weeks after treatment. The residues were extracted using acetone and used for three determination.

(i) The quantities of extracted'sulphoxide and sulphone were chemically assayed (Table 38). The 1970 data for the residues in soil treated one year earlier (May 1969) in Church Field and High Field were kindly provided by

Dr. R. Skrentny (Tables 34-36). (ii) In some cases the concentrations of residues were too high for present studies and the soil was diluted with uncontaminated soil to give a suitable range of concentrations based on the estimated quantities of toxicants in the soil. The treated and dilutant soils were mixed together in a culture jar mounted on a shaker for 30 minutes, and the mortalities of F. fimetaria placed on it were determined (Table33).

(iii) The extracts were pipetted onto uncontaminated soil for comparison with the diluted - soil assay in (ii) above and mortality of F. fimetaria assessed (Table33)• 5 grins of treated soils and soils from the control plots were placed in 4 oz. plastic containers and sufficient water was added to moisten the soil and then known 11+6.

numbers of insects released into the containers. The

containers were closed with a tight fitted lid (Table 36).

Containers were held in a cabinet at controlled temper-

ature and humidity, as described earlier for T. krausbaueri

and mortality counts were made periodically. Final

mortality counts in each method were ascertained by

floating dead insects. The extracts used for Dr. Skrentny's

chemical determination in (i) above were pipetted into

filter papers and mortalities were assessed (Tables 34, 35).

(f) Mortality determination

Live insects moved freely and did not show agitation

to a gentle touch of a squirrel hair brush. In Folsomia sp.

crawling and jamping were normal responses.

Insects categorised as dead were those which showed

no movement even when lightly stroked with a brush.

Affected or moribund individuals were also counted as dead

and furcula were fully stretched in dead Folsomia.

Affected insects appeared sluggish, lying upside down,

showing agitation when touched and also paralysis. Severe

symptoms of poisoning were convulsive twitching of append-

ages or flexing of abdomen which became feebler and more

spasmodic as death approached. Crawling and a jumping

movement in Folsomia was decreased corresponding to the

increase in the degree of poisoning. Dead Folsomia had a

thin secretion of fluid around their body while in

T. krausbaueri secretion in droplets was observed on the

lateral sides of the abdomenal and antennal segments. 147,

Secretion in T. k:rausbaneri war probably from pz;oudocelli

as they arc know to release an odour as a defence

mechanism. (Goto, 1970).

(g) Statistical treatments

Dosage - mortality curves were calculated for each

individual time of observation for each insecticide and

species and analysed probits analysis (Finney, 1962), with

the aid of an electronic computer. Time-mortality responses

were tested for parallelism and relative LC.50,s calculated

where parallelism was evident.

2. Results

The dosage response curves are illustrated in (Figs.27-32)

and the probit analysis summarised in Tables 26-33.

F. candida is more susceptible to aldicarb sulphoxido

than T. krausbaueri in spite of its relatively larger size.

for F. candida and T. krausbaueri were 0.13y.g. The LC50's and 0.21 )1g.respectively (Tables 26, 28). However, the lines

are not parallel (Fig.27) and the comparison of relative

susceptibilities at one response although illustrating the

general point do not hold true for all response levels.

The toxicity of aldicarb was about 4 to 6 x greater

than that of aldicarb sulphone on the basis of mortalities

24, 48, and 72 hours (Fig.28) after treatment.

The non-parallel nature of the aldicarb sulphoxide

regression line makes it difficult to make a similar

comparison but responses generally lay between the aldicarb 1 48.

7.0

6.0

-J

5.0

0 cx 0

4.0

2•S 3.0 3•S 4.0 DOSE ALDICARB SULFr6XIDE (Log 10 /ug + 4

Fig. 27. The toxicity of aldicarb-sulphoxide to

F. candida••••••■•■■•••••■••••••••■•• and T. krausbaueri based on 48 hours mortality (Filter paper treatment method).

F. candida (0 ) T. krausbaueri 149.

0 7.0 0 A

6.0

-J -J

-- 5.0 0 a_

4.0

2.5 3.0 3.5 4.0 DOSE (Log to pg )

Fig. 28. Toxicity of aldicarb, aldicarb-sulphoxide and aldicarb-sulphone to T. krausbaueri on the basis of 72 hours mortality (Filter paper treatment method).

Aldicarb Aldicarb-sulphoxide Aldicarb-sulphone 150.

6.0

■ 11.0.1•11 2.5 3.0 3.5 4.0 DOSE CLog1opg+4)

Fig. 29. Comparative toxicity of Aldicarb and aldicarb-sulphoxide to T. krausbaueri using filter paper and soil treatment methods of bio-assay (based on 24 hours mortality).

Aldicarb (0) Filter paper treatment Aldicarb-sulphOxide(A) Aldicarb (0) Soil treatment Aldicarb-sulphoxide(x) 151.

PROBIT. KILL 4z• O 0

0 m w 0 r- 0

(.4

Fig. 50. Toxicity of aldicarb and zinophos to

T. krausbaueri based on 24 hours mortality (Filterpaper treatment method)

Aldicarb (0) • 4Zinophos ( a) 152.

D5 D4 0 3

0 8 24 48 72 TIME HOURS)

Fig. 31. Mortality responses curves of T. krausbauori to Aldicarb and t Zinophoe (Filter paper

treatment, method). 153.

PROBIT. KILL rN) Co cn 1:7% O 0 0 0 0 0 I

▪ woo MN wow

♦ ♦

DO ♦ ♦ SE A 2

.5 10

r LDI ♦

4.0 C 0 A 0 RB

uo - 3 .0 S

4 ULPHO 0 XIDE 3 .5

Fig. 32. Toxicity of aldicarb-sulphoxide to F. candida based on 48 hours mortality. (Filter paper treatment method). 154. Table : 26 (a)

The toxicity of Aldicarb-sulphoxide to F. candida (Filter paper treatment method) based on 24 and 48 hrs. I II Probit Analysis and Test Parallelism

Parameters of 95% confidence Probit Line Heterogeneity LC 50. limits of LC:50. ()-1 g) a. b+S.E. 1.; D.F. P. Lower Upper

I -0.22 1.52+0.15 0.48 2 0.80 0.26 0.23 0.31 II -2.26 2.34+0.17 5.32 2 0.08 0.13 0.11 0.14

Table: 26 (b)

Test of Parallelism Control b+S.E ' Parallelism of Regression Relative Mortality 2 'X D.F. P LC 50 1.89 12.18 1 0.01 I 1.00* 2.0 II 0.48 4.6

* The data contradict the Hypothesis of parallelism

155.

Table: 27(a)

The toxicity of Aldicarb-to T. kraubaueri (Filter paper treatment method) based on 8, 24, '32, 48 and 72 hours I II III IV V Probit Analysis and Test Parallelism

confidence Parameters of Heterogeneity Lr:50. 95% Probit Line (pg) limits of LC:50

a. b+S.E. '3C2D.F. P. Lower Upper

I -4:14' 1.78+0.22 4.46 2 0.11 0.29 0.23 0.37

-0.16 1.58+0.18 5.26 3 0.15 0.12 0.10 0.15

IIT -0.59 1.93+0.20 1.23 2 0.55 0.08 0.06

IV -0.20 1.88+0.21 0.33 2 0.85 0.06 0.04k 0.07

V -1.18 2.30+0.26 1.11 1 0.35 0.05 0.04 0.06

Table: 27 (b)

Test of Relative Control b+S.E Parallelism of Regression Mortality 2 'X D.F. P LC.,50

1.85+0.09 5.71 4 0.25 r 1.00 2.2 II 0.43 2.9 III 0.27 4.o IV 0.21 4.8 v 0.15 5.1 156.

Table: 28 (a)

The toxicity of Aldicarb-sulphoxide to T. Krausbaueri (Filter paper treatment method) based on 8, 24, 48 & 72 hrs. I II III IV • Probit Analysis and Test Parallelism

Parameters of Probit Line Heterogeneity LC 50. 95% confidence •91g) limits of LC.50 a. b+S.E. D.F. • P. Lower Upper

1.44 1.22+0.14 6.29 3 0.10 0.83 0.60 1.33 1.65 1.28+0.14 6.21 4 . 0.18 0.41 0.32 0.57 1.81 1.37+0.14 6.63 4 0.17 0.21 0.17 0.27 11.90 1.43+0.23 11.27 4 0.02 0.15 0.08 0.25

Table: 28(b)

Test of Parallelism Relative Control b+S.E Parallelism of Regression Mortality D.F. P LC:50

1.33+0.10 1.9 3 0.82 1 1.00 0 II 0.54 2.3 III 0.28 3.8 Iv 0.19 4.2 157. Table: 29 (a)

The toxicity of Aldicarb-sulphone to T. krausbaueri (Filter paper treatment method) based on 24, 48 & 72 hrs. I II III Probit Analysis and Test Parallelism

Parameters of Probit Line Heterogeneity LC 50 95% confidence (pg) limits of LC 50 2 a. b+S.E. D.F. P. Lower Upper

-1.35 2.32+0..24 1.84 2 0.40 0.54 o.54 0.64 -0.51 2.17+0.21 .4.02 3 0.25 0.34 0.29 0.40 _0.11 2.14+0.20 7.75 3 0.06 0.24 0.21 0.29

Table: 29(b)

Test of Parallelism Relative Control b+S.E. Parallelism of Regression Mortality 2 D.F. P L:C 50 90

2.20+0.12 0.35 2 0.85 1.00 2.3 II 0.63 4.o III 0.45 5.4. 158. Table: 30(a)

The toxicity of'Zinophos to T. krausbaueri (filter paper treatment method Y- based on 8, 56 and 72 hours I II III IV Probit Analysis and Test Parallelism

Parameters of Probit Line Heterogeneity LC 50 95% confidence (pg) limits of LC:50

a. b+S.E. ' D.F. P. Lower Upper .17 1.37+0.18 0.21 3 0.96 0.33 0.25 0.46 1.35 1.504.16 0.64 3 0.88 0.15 0.12 0.20 1.86 1.12+0.16 4.75 3 0.20 0.06 0.04 0.08 1.30 1.37+0.17 0.91 3 0.93 0.05 0.03 0.06 .72 1.66+0.20 0.61 2 0.75 0.04 0.03 0.05

Table: 30 (b)

Test of Parallelism Relative Control b+S.E. Parallelism of Regression Mortality D.F. P LC 50

1.31+0.08 .5.84 4 0.22 I 1.00 1.9 II 0.44 1.9 III 0.20 3.5 IV 0.14 4.4 V 0.09 .5.0

159. Table: 31 (a)

The toxicity of Aldicarb to T. krausbaueri (soil treatment method) based on 8, 241 and 36 hours

Probit Analysis and Test Parallelism

Parameters of Probit Line Heterogeneity LC:50 95% confidence (pg) limits of LC:50

2 a. b+S.E. "X. D.F. P Lower Upper

.,285 1.90+0.22 1.93 2 0.37 0.30 0.25 0.38 2.09 1.41+0.17 2.78 3 0.45 0.12 0.09 0.15 2.02 1.67+0.19 1.75 3 0.60 0.07 0.05 0.08

Table: 31 (b)

Test of Parallelism Relative Control b+S.E. Parallelism of Regression Mortality

X2 D.F. P LC 50

1.63+0.11 3.29 2 0.20 I 1.00 1.7

II 0.36 3.1

III 0.19 13-.7

160.

Table: 32 (a)

The toxicity of Aldicarb-sulphoxide to T. krausbaueri (soil I II treatment method) based on 8, 24 and 361gurs. Probit Analysis and Test Parallelism

Parameters of Heterogeneity LC 50 95% confidence Probit Line (dig) limits of L<7.50

a. b+S.E. %2 D.F. P Lower Upper

_.90 1.97+0.35 0.93 2 0.70 1.01 0.78 1.54 .98 1.51+0,,20 3.28 3 0.35 0.47 0.40 0.62 1.38 1.48+0.19 5.11 3. 0.17 0.29 0.23 0.36

Table: 32 (b)

Test of Parallelism Relative Control b+S.E. Parallelism of Regression Mortality 2 1, D.F. P . 50

1.57+0.13 1.83 2 0.42 I 1.00 3.2

II 0.39 4.5

III 0.24 5.7 161.

Table: 33 (a)

The toxicity of Aldicnrb and its metabolites+T ____ to F. fimeteria treated - dilutant soil method based on - 24 ana_48.hours And also soil extract from Aldicarb . I II treated plot 1970 apnlied to uncontaminated soil2

Parameters of LC5O. 95% confidence Probit Line Heterogeneity (jig) limits of LC 50

? a. b+S.E. IS D.F. P Lower Upper

a 6.05 1.58+0.16 0.29 1 0.60 0.22 0.17 0.27 316.59 1.61+0.17 1.39 1 0.50 0.10 0.08 0.13

15.30 1.881.0.26 3.66 2 0.17 0.69 0.57 0.91 315.72 1.64+0.24 2.62 2 0.10 0.41 0.34 0.49

Table: 33 (b)

Test of Parallelism Control b+S.E Parallelism of Regression Relative Mortality ? D.F. P Io.,C 50

1,59+0.12 0.02 1 0.95 i 1.00 0

IT, 0.47 0

1.86+0.18 0.01 1 1.00 11.00 1.2 If 0.58 1.2

+ Aldicarb and its metaboliteswF.u^o chemically estimated in the soil (0-6" layer) 3 weeks after application, 162.

Table: 34. Comparative toxicity of residual metabolites of aldicarb extracted from sandy and clay soils one year after application to 5-6- weeks-old adults of F. fimetaria

Layer Type Residual Mort- Compar- Mort- Compar- of of metabolites ality ison* ality ison* soil soil in soil after of after of sample 24 sandy 48 sandy (in ins Concen- hours with hours with Chemi- tration cal (%) clay (50 clay (PPm) soil soil , —

Sandy SO -04-0.02 26 41 SO2 = ND 0-6 P(0.01 P0.01 Clay SO .43.0.0l 6 14 SO2 = ND ----.1.- Sandy SO =4170.01 7 17 " SO2 = 0.01 _ not ____- not 6-12 signi signi ficant ficant Clay SO @0.01 8 10 SO2 . ND ._

Sandy SO .0•0.01 10 19 SO2 = ND 12-18 ------p46.o5 . — P6.01 Clay SO = ND 1 4 SO2 '= ND ______. ••■•".11•••••••••• _- Con- Sandy No residue trol 0 2 . ..- not signi Con- Clay No residue ficant trol 0 0

A 1 1 . Notes: *The significance of each difference in mortality was assessed with the tables of Mainland et al., (1956) SO = Sulphoxide S02, = Sulphone ND = Not detected by thin layer Chromatography 163.

Table: 35.

Comparative toxicity of residual. metabolites _.._.____of aldicarb extracted from sandy and clay soils one year after application to 1 week-old larvae of F. fimetaria

Layer Type ResiduE 1 Mort- Compar- Mort- Compar- of of metaboli tes ality ison' ality ison* soil soil in soi 1 after of after of sample 24 sandy 48 sandy (in ins) Chemi- Co/ cen - hours with hours with cal trE tion (96) clay (%) clay (p1 m) soil soil V.

Sandy SO .!-C0 .02 100 100 = 1 D SO2 0 - 6 P4p.ol Clay SO 4..0 .01 8o 100 =1 SO2

Sandy SO 41C).01 91 100 = C .01 302 6-12 P<0.01 Clay SO (.a( .01 100 100 = I SO2 . _ D.01 Sandy SO 'LL( 93 100 SO = ] D 12-18 2 - P(0.01 Clay SO = ] 56 78 SO2 =

Con- Sandy No residu 1 5 trol not not ------signi signi ficant ficant Con- Clay No residue 0 10 trol

Notes as for Table 34. 164.

Table: 36.

Qualitative effect of aidicarb treated soil (one year after aldicarb treatment in the Church Field soil) on the life stapes of Folsomia flmetaria

Layer Aldicarb Concen- Number* Observations on the of soil Meta- tration of live stages in cultures sample bolites (ppm) insect (inches) detected released 1 week 6 weeks 13 weeks initialy (adult) A

0-6 SO 40.02 Adults Adults & Few adults 193 few eggs few SO = ND larvae & 2 few eggs

6-12 SO ti 0.01 Adults Adults & Adults & 171 few eggs larvae & = 0.01 few eggs SO2

12-18 SO Adults & Adults & Adults & few eggs few eggs larvae & SO = ND few one egg 2 larvae cluster & few eggs

Con- Adults & Adults & Adults & trol + No residue 549 egg egg egg clusters clusters clusters & & juven- & & juveniles larvae iles,larvae

Notes:

There were 3 replicates for each soil sample. Control observations were recorded from 3 corresponding different layers of uncontaminated soil samples and not enough differences were observed to categorise independently; therefore general observation is incorporated.

ND No detectable quantity.

SO Sulphoxide

Sulphone SO2 165. and sulpbone responses. T. krausbaueri showed an order of susceptibility to nlAinavb and its toxic metabolites similar to that reported by Skrentny and Ellis (1970) using Aphis fabae, even though their quoted of LC50's sulphoxide and sulphone were more than 10 x than those observed for T. krausbaueri in the present studies. The effectiveness of aldicarb and sulphoxide to T. krausbaueri was similar when insecticides were tested by the filter paper and soil treatment methods on the basis of 8 and

24 hours observations (Fig. 29 ).

Comparing the susceptibility of T. krausbaueri to aldicarb and'iinophosshowed that, up to 24 hours, less aldicarb thanIinophos was required to produce 50% kill but 48 and 72 hours mortality observations did not show (Fig.30) . Again the lines substantial differences in the Le50's were not parallel and this can only be a restricted

hours were 6.5 and conclusion. The L.150's after 8 1 11.1 x greater for aldicarb and tinophos respectively, when compared with the dose calculated for 72 hours under the restriction of parallelism.

It is clear that 24 and 48 hours mortalities of

F. fimetaria on extracts from sandy soil (0-6" and

12-18" layers, were significantly higher than the corres-

ponding extracts of the clay soil (Table 34). Comparison

of extracts from the 6-12" layers, from sandy and clay

soils showed no significant effects. The patterns of

toxcicity are broadly similar for larvae and adults

(Tables31h 35). However, larvae were more susceptible 166.

than adults and the differences were more highly significant

probably due to the higher susceptibility of the former,

and thus small differences in toxicants would produce a

greater than proportionate response compared with the adults.

Control mortalities were appreciably higher in juveniles

than in adults.

When the residues of aldicarb-sulphoxide and sulphone,

were extracted from treated soil and applied to clean soil

it was less toxic to F. fimetaria than the original treated

soil. The estimated L.E50's on the field treated soil were (0.25.,ug.) and (0.21 Ag.) after 24 and 48 hours

respectively, using the quantities of chemically determined

insecticides as a basis.

Time mortality responses of T. krausbaueri for each

dose of aldicarb and'71noDhosare presented in Fig. 31.

The concentration of aldicarb and .7inophos were 0.0313,

0.0625, 0.1250, 0,2500, and 0.500,ug. Curves show a

tendency of flattening-off in the 48-72 hours region for

aldicarb treatment but in the case of'-iinophos the flattening-

off did not appear by 72 hours (the maximum period of

observation).

3. Discussion

Juveniles of F. fimetaria_ . were more susceptible than adults, but their response to soil extracts was broadly

similar to that of adults. Significant differences in

mortalities in extracts from sandy soil (0-6" and 12-18"),

were due to higher residues of sulphoxide and sulphonu 167.

than extracted from similar layers of clay soil. However, significant mortality differences were not observed between clay and sandy soils extracts from 6-12" layers (Tables 34, 35). Since there were differences in the detected chemicals in the 6-12" layers (Tables 34, 35 ). Reasons for such differences in mortalities are obscure.

Although extracts from clay soil from (6-12") contained less aldicarb sulphoxide and sulphone, they might contain some toxic metabolites which were not present in the extract of sandy soil. Both types of soils do play different roles in the degradation of aldicarb (Skrentny, 1970), but on the basis of their characteristics (Pain and

Skrentny, 1969) no conclusion can be drawn from such differences in the susceptibility of adult and larvae of

F. fimetaria. From the viewpoint of findings reported by

Bull et al (1970), especially in relation to pH differences of soil, the application of radio-active aldicarb was thought to be the only suitable answer of investigating the afore-said problem; but due to lack of time this was not carried out. This would seem to be an important consideration since recently Williaq et al (1970), studied the metabolism of aldicarb in cotton plants and

detected ten major and twenty overall metabolites of pesti-

cides using radio-tracer technique and mass-spectral

analytical method.

From the extrapolation of the fitted regression line

(Fig.32), calculated for determining the toxicity of aldicarb sulphoxide to F. candida, (48 hours mortality), 168, it was estimated that 0.01 ppm concentration would have

accounted only for 0.6% kill of the insects. Although in

the current studies F. fimetaria. _ was used, comparison of Folsomia species was considered intereuting from various

toxicological reasons. It is observed from Table 34 that the lowest mortality after 48 hours, due to the

chemically estimated sulphoxide and sulphone, was 4% and

the highest was 41%. Thus, overall increase in the

toxicity as compared to the estimated 0.6% (if only

sulphoxide had been involved), indicates the presence of

other toxic metabolites in the soil extracts which were not identified. Moreover, unknown toxic metabolites were

presumably in higher quantities in sandy soil than in

clay soil as revealed by mortality counts of F. fimetaria.

This suggests that the persistence of toxic metabolites

of aldicarb was more in sandy soil than in clay soil,

which supports present chemical estimations and also

numerous reports by other workers (Bull et.a1.1970). The

overall rate of disappearance of aldicarb reported by

Skrentny (1970), was similar to the present findings on

the persistence of insecticides revealed by toxicity tests.

There is strong evidence from the bio-assays that

chemically determined concentrations of aldicarb sulphoxide

and sulphone in soil extracts were not the true represen-

tation of potential metabolites of aldicarb. Experiments

indicate that in the process of chemical extraction of

treated soil some unknown toxic derivatives of aldicarb

were either lost or they were broken down to non-toxic 169.

metabolites. It may bo suggostod that the residues of

sulphoxide (SO) and sulphone (S02) as determined by

the current TLC method, may not hold as a standard for the

toxicity test against Collembola (F. fimetaria), for

prediction or assessment, of the affected insect population in the field, due to the aldicarb treatment. The only

possible reason for the high toxicity of treated soil, by itself, may be due to the presence of toxic materials

produced by higher Macro or microbiological activity after

aldicarb treatment in the 0-6" layer of sandy soil.

Very little is known from the literature regarding

the toxicity of aldicarb andlinophos to Collembola using

standard laboratory bio-assay techniques. Scopes (1965)

pointed out that the sensitivity of 6 days old Folsomia

cavicola (Bouteville) toiiinophos' was 0.003,Ag (when o insects were exposed for 24 hours at 25 C.). Present

studies have shown that for fiinophoe the LC50,s to T. krausbaueri adults may vary in the range of 0.038 to 0.33, yg. Low values indicated by Scopes might be

accounted for by the early age of the juveniles as well

as for a different species.

Scopes and Lichtenstein (1967) calculated 0.53, Ag

for aldicarb against F. fimetaria on the as the L.050 basis of 8 hours exposure period on insecticide - contam- Amated filter paper. F. candida in current investigations

showed a similar range of toxicity allowing for unidentical methods and conditions of assays. Considering the relative

toxicity of aldicarb and the sulphoxide against T.

krausbaueri, it may be said that F. candida is slightly 170.

more wAccoptible than F. fimetaria. It was observed that

the larvae of F. fimetaria (Table 35) were highly susceptible to sulphoxide and sulphone residues; therefore, this stage is promising as a test insect for determining

the residue of aldicarb and its toxic metabolites especially when present in low concentrations.

In preliminary studies on the toxicity of aldicarb to

F. candida adults, it was noticed that the insecticide has a rapid narcotic, but not necessarily lethal, effect even at comparatively low dosages, and insects removed from the treated containers often recovered. Parker et al, (1970) used aldicarb against Daphnis magna (Straus) and found that the species were highly sensitive to the insecticide

(LC = 0.82, .,ug in 30 minutes). It may therefore be 50 suggested that similarly F. candida might prove to be a

useful animal for detecting minute concentrations of

aldicarb in a short period.

Edwards et al, (1967) have found that F. candida was

more susceptible than Tullbergia sp to aldrin. In current

studies, the order of susceptibility of T. krausbaueri and

F. candida to aldicarb-sulphoxide was similar to the report

by Edwards et al,(1967)Iiinophosl was less toxic than aldicarb to T. krausbaueri and similar relationships of insecticides

were reported by Skrentny and Ellis, (1970) with A. fabae,

although variations in toxicity of individual insecticides

were considerable. Toxicity data on aldicarb and'iinophos'

indicated that T. krausbaueri was 10 and 5 times more susceptible than B. brasoicae when compared with the data 171 x.erdoi by Ahmed (1970) and Galley (1968) respectively for the same period of exposures.

'Zinophos% an organo-phosphorus insecticide, showed that the mortality periods selected wore not toxicologically precise. It is evident that a low dose of the insecticide acting, for a long time, may be as effective as a high dose acting for a short time. Therefore, it may be suggested that for future work, longer observation periods for mortality counts should be considered until the levelling of the time mortality curves are observed. This might then be more indicative of the field responses expected.

Although'Zinophos'has some fumigant action the present

handling and opening of the container probably minimised

this effect.

Up to 24 hours different dosages of aldicarb showed

an erratic pattern of toxicity which is broadly true of yon41/0, 04 e carbamates (O'Brien,/1970), but thereafter responses

became more parallel. The rapid oxidation of aldicarb to

form sulphoxide, and consequently sulphone, in the chain

of aldicarb metabolism in vivo (Metcalf,et. a1.1966),.may be a

strong reason for the response shown by the curves (Fig. 31 ). 172.

SECTION IV.

THE EFFECT OF ALDICARB ON SOIL FAUNA IN SANDY SOIL AT CHURCH FIELD 1970 The experiments described in the preceding sections

were essentially to compare the effects of aldicarb and

'Zinophos'on the fauna in two soil types, sandy and clay.

The information on chemical residues was obtained from

other workers using the same area. In 1970 it was decided

to use only one plot treated with aldicarb in order to

confirm the patterns of response to this particular

pesticide and to further evaluate the sequence of

recolonisetion by soil fauna. The interaction between

predator and predator species and the insecticide was

also a major consideration.

Aldicarb was chosen as the treatment since it had

less drastic effects on the soil fauna thanlinophosi but

was more persistent. The residues of aldicarb were

chemically determined by thin layer chromatography (T.L.C.)

and the effect of these residues on soil organisms deter-

minted by sampling the soil organisms. The frequency of

sampling was increased to shorten the intervals between

observations.

The methods of analysis are presented in Appendix

5B( p. 280-81). 173.

1. Materials and Methods

(a) Experimental Design and Sampling The experimental plot used was the control plot located in block B of the original 1968 plots of the

Church Field (Fig. 1 ). This plot was adjusted to the dimensions shown in order to avoid the previously treated areas. The total area of the plot was 196 square yards.

The area was divided into two parts:-

(a) An outer border 2 yards wide (1, Fig.33 ) extending around the whole of the plot and 96 square yards in area.

(b) The inner area of 100 square yards was treated with aldicarb. This area was sub-divided into three sections (2, 3, 4, Fig.53 ). Section 2 was a band 1 yard wide, section 3, 2 yards wide and the centre section 4, 4 x 4 yards. The areas were further subdivided using string into

areas 1 x 1 yard to facilitate sampling. The plot had

been sown with the potato variety, Penland Dell in 1969

and the crop was left in situ-, On the 5th May 1970 aldicarb

was applied at the rate of 10 lbs. active ingredient per acre

(10% granules) to give an estimated 5 ppm. in the soil

to 6" depth. Area 1, the untreated area, was screened from the treated area during application of the insecticide

by using polythene sheet. After treatment the granules

were lightly raked into the soil (Fig. 34 ).

The plot was sampled in April 1970 before treatment

and at two week intervals after treatment. The samples

were taken to a depth of 9" and the fauna extracted using 174.

10 YARDS

• • . • • • • • • • • • • . = • • i s • • • I • • • • • • I • • • • I • I • • • • I • • . • • • • • • • • • • • • • • • • • • • . • • • • • • • • • II • • • • • U) . • • • • • • • • • • • • • • • • • cc ■ • • • •• •• • • • . • • • • • • • )- • • • • • •• • • ® • •• • • • • • • I • f • --n- • • • • • • •• .

• • • 8 • • • • • •• • • • • • • • r 49 • • • i • • • • • • • •• • • • • • • • _

• • • • • • • • • • •

• • •e •

Fig. 33. Plan of the experimental plot of 1970 at Church Field howing the pattern of sampling

• points . 175.

the grcidi‹,nt method. A restricted random sampling was

employed. 8 samples woro fnkon from area 1, two random

samples from each of the four sides, and similarly 6 and 4 samples were taken from areas 2 and 3 respectively. Only two random samples were taken from area 4. The vertical distribution of micro-arthropods was

studied by dividing the 0-9" cores into three depths,

0-3", 3-6", and 6-9" and compared using mean population

estimates and the changes in the faunistic composition.In

relation to treatment, soil applied aldicarb and untreated

areas were analysed on the basis of these mean populations (Table 37). It was observed that most of the soil fauna was confined to the 0-6" depth, therefore, residues of the

insecticide were determined from this depth.

(b) Chemical estimation of aldicarb from the soil determined by (T.L.C.) method (1) Soil sampling

An auger of one inch internal diameter (Fig. 3-Ta)I. Vitn used for taking the samples from treated and untreated

areas at 0-6" depths. It consisted of a graduated steel

tube corer of 1" diameter. Two-thirds of the side was cut

away along the length of the shaft except for the bottom

inch. This 'cut-away' minimised compression of the soil

samples and facilitated their removal. The cutting edge

was kept sharpened. Ground, if dry, was irrigated lightly

to facilitat2the sampling process. Fig.34. Treated and untreated areas seperated with polythene sheet. kiliglikaAAAAA

Fig.34a. Sampler of 1" diameter. 177.

All ton random pAmplc6 Ear the treated and untreated

aroms were taken separately, pooled and thoroughly mixed.

Air-dried samples from the plot were kept in labelled

polythene bags and stored in a deep-freeze at -20°C. (+ 0.5°C.). These soil samples were used for extracting residues

of aldicarb metabolites - namely sulphoxide and sulphone

using thin layer chromotography as the analytical method.

(ii) Preparation of Samples and clean-up procedure To determine the insecticidal residue in each of the

soil samples 200 grins. of air-dried aliquot were weight

into a 400 ml. jar and 20 grins. of anhydrous sodium

sulphate were added. 150 ml. of an equal mixture of

acetone and chloroform were then added to the sample which

was subsequently thoroughly homogenised, using au electric

homogeniser (M.S.E.) for 10 minutes. The jars were

covered with tin foil, tightly capped and allowed to stand

for approximately 12 hours. The thoroughly mixed solvent -

soil mixture was filtered through a Buchner funnel, having

three filter layers i.e., woolly asbestos (a thin layer at

the bottom to retain the soil particles), hyflo supercel

(a layer of 3-4 grin. material to facilitate the flow) and

sodium sulphate (anhydrous, a layer of 3-5 grms, to retain

the water molecules). The efficiency of the filtration was increacied by

connecting the Buchner funnel to a simple hydrolic unit

for reducing pressure from the laboratory water supply to

avoid a cloudy extract. The operation of pressure

reduction was regulated by varying the flow of the tap

water. 178.

After the recovery of the solvent mixture the soil was removed from the funnel, 150 ml. of solvent mixture was added, and homogenised and the filtration process repeated. The filtrates collected from both processes

were mixed and concentrated with the use of a rotary film

evaporator at 40-45°C. Aldicarb evaporates at 50°C.,

hence the selection of this temperature.

The concentrate was transferred into a measuring

cylinder and the volume made up to 50 ml. using the

analytic grade acetone which had been used to rinse the

evaporator flask, It was kept in airtight glass jars

containing 2-3 grms. of anhydrous sodium sulphate.

One ml. of soil extract, equivalent to 4 grms. of

original soil sample, was pipetted into a beaker contain-

ing a thorough mixture of 1 grm. of decolonised charcoal

(Norit NK) and 0.25 grm. of hyflo supercel for further

clean-up. The solvent was then evaporated under a fume

hood using a gentle jet of nitrogen, until the odour of

acetone had disappeared.

50 ml. of re-distilled hexane was added in parts

onto the residue and poured into the chromatographic

column of Florisil (5 grms., 60-100 mesh) until it was

completely transferred.

Most of the filtrate was discarded in order to remove

the impurities of aldicarb. This was necessary because,

although aldicarb is not itself soluble in hexane, other

unknown undesirable materials may have dissolved in it

which could have interferred with the analysis. 100 ml.

of acetone was eluted through the column. 179.

The column consisted of a glass tube of 20.8 cm. in longth with a constriction at the bottom and an internal

dinmeter of 1.8 cm. The bottom end was packed with asbestos

wool, one grin. of granular sodium sulphate was placed above

this and on top 5 grins of florisil. Finally the column was

covered with another 1 gm. layer of sodium sulphate.

The chromatographic column was held in a 250 ml. conical

flask. The acetone-based extract collected in the flask

was concentrated, using the rotary film evaporator at 40°C.,

as described above, until the extract volume was reduced

to 2.5 ml. The concentrate was then transferred to a 10 ml.

centrifuge tube and the flask rinsed a few times with

acetone which was then used to make up a final volume of

8 ml. in the tube, depending upon the actual concentration

of the insecticides.

A range of various concentrations, covering those

most likely to be found, was made for purposes of ccnpari-

son with known standard solutions. It is useful to

mention here that the quantities represented by soil

extracts were easily calculated back to the original soil

samples for the convenience of final concentration used in

bio-assays. Tubes were then fitted into a beaker containing warm

water at 40-45°C. The temperature was maintained by the

addition of water. A controlled, gentle jet of nitrogen

was passed over the surface of the liquid until the solvent

completely evaporated. 10 u1. of pure acetone was added

to the centre of the tube by means of a microsyringe and 180.

the oamplo then rottAbod to disco11re nny adhering insecticides

from the side of the tube, and the assessment was carried out using these samples.

(iii) Preparation and processing of T.L.C._ plates

T.L.C. glass plates (20 x 20 cm.) were used by being

coated with silica gel G and activated in an oven at 100°C.,

for one hour. Points for each sample (standard and unknown)

were marked along a straight line, leaving sufficient

margins, with a steel needle, on silica gel coated side.

A constant micro-quantity of each sample was applied

by means cf a micro-capilliary tube to respective points.

Micro-volume on each point was delivered by eye estimation

and a gentle flow of air was used to confine the chemical

in the spot. 10 ,Al. of acetone was again added to the

sample tube and re-applied to the same spot. For each

unknown sample, simultaneous spots were treated with unknown

or standard concentrations of aldicarb, sulphoxide and

sulphone in the range of 0.5 - 5,ug. Known quantities of

aldicarb, sulphone and sulphoxide were delivered in

concentrations of 0.5, 1, 2.5 and 5,ng. for each insecti-

cide on the same spot in increasing order.

Treated plates were suspended vertically in a covered glass tank which contained a developing solution

of ethyl acetate and acetone (25: 4 by volume).

Observations were made until the solvent reached about

30 mm. from the top of the T.L.C. plate, which took about

30 minutes. The plates were removed and dried then

sprayed with two chromogenic re-agents, first 10% aqueous 181. sodium hydroxide, heated for three minutes at 70°C., cooled, and secondly oversprayed with 2% ninhydrin in 65% ethanol and then reheated for 30 minutes at 70°C., as Skrentny (1970)

described. This increased the sharpness of the red spots especially of the trace amounts and this method was found to be more sensitive than when the plates were sprayed with a pyridine solution of indanetrione hydrate (1%)

(Skrentny and Ellis, 1970).

Spots for aldicarb appeared at the top, those for sulphone in the middle and, at the bottom, those for sulphoxide. They appeared in a band. Aldicarb, its sulphoxide and sulphone, developed rod spots due to the amines produced from the carbamyl group at Rf 0.61,

0.06 and 0.39 respectively (see Metcalf et. al., 1966).

Amounts of insecticides were estimated by comparing the size and colour intensity of the spot with known standards applied on the same plate as described earlier.

(-.7) Calculations for the quantities of residual insecticides in the soil

It is evident from the analytical method described above that known quantities of the soils were used in preparing concentrates of unknown Quantities of insecticides, which were chemically analysed. Thus estimated quantities were utilised by dividing the,gg. of recovery sulphoxide or sulphone by the per unit grins., giving parts per million concentrations (ppm.) of the metabolites concerned in the original soil samples. Where spots could

be observed (but the accuracy was not reproduceable at

traces(0.01)is indicated in Table38 for corresponding insecticides. Where spots were not detected the term

"ND" is used. 18?.

2. Results (a) Chemical degradation

Rate of degradation (Table38), was rapid when compared

with 1969 estimates (AppendixT.6 after Skrentny 1970).

Edwards (1970) stated that rainfall and cultivation both

affect the presence of insecticides. Rainfall during

July 1970 was 58% higher than the corresponding period of

1969 (Appendix T.7) and soil was undisturbed. Therefore,

it appears that both of these factors were responsible for

the faster degradation or leaching of aldicarb - metabolites

to deeper layers. Influence of water on the loss of

aldicarb has been shown by Bull et. al., (1968).

(b) Analysis of populations

Due to insecticidal application to the soil, the

fauna was affected considerably. Proportional changes in

the aldicarb treated area compared with the control are 3 shown in Table6$9, 40). DensIZtias of total Collembula and er4‘A4/c5 other ar+hrrputs were decreased by 33% and 77% respectively,

while predatory and other mites increased by i,% and 36%

respectively. Reasons for the increase in mite population

are discussed later. The sample numbers and the mean

number of invertebrates in 0-9" cores are given in Table 37.

Interpretations are based on the mean population counts as

the numbers of samples were not uniform. Results for

individual species are described below: 183.

Table: 37

The mean number of invertebrateSin 0-9" cores in Aldicarb treated and untreated areas in Church Field from May to November 1970

. May June July Aug. Sept. Oct. Nov. CACACACACACACA

O. trinotatus 41 1 10 1 29 13 4 2 23 4 8 6 10 2 T. krausbaueri 155 64 186 54 188 138 121 116 290 182 113 218 102 124 Hyrogastrurids 1 0 1 0 0 0 1. 0 0' 0 '2 0 0 0 L. cyaneus 3 0 5 0 13 0 6 1 1 0 3 3 3 8 F. quadrioculata 2 0 2 0 3 0 0 0 8 0 1 .0 1 0 liolsomia species 0 1 2 0 8 0 5 2 1 0 0 33 0 21 I. productus 14 0 0 0 52 6 3 0 13 0 23 12 8 4

I. thermQphila :8000 2 0 1 1 0 6 0 0 0 0 I. viridis 2 0 4 0 18 0 5 2 14 0 6 6 25 11 Tomocerids 0 0 0 0 0 2 0 0 0 0 0 0 0 0 Symphypleona 3 0 0 0 0 0 0 0 0 0 0 2 0 1 Rhodacarids 2 0 0 0 1 0 0 0 1 0 5 0 0 1 Pergamasus species , 2 3 2 2 9 3 3 6 2 4 3 5 20 1

Other gamasids 16 0 3 0 7 1 3 0 4 15 5 4 0 1 (adults) Gamasid nymphs 86 41 4 0 42 19 18 58 0 26 6 0 0 100 Uropodina 0 0 0 0 4 0 15 7 0 3 5 8 3 0 Cryptostigmata 4 0 0 0 4 0 0 0 0 •0 0 5 0 0 Prostigmata (adult) 8 8 10 10 10 8 7 5 1 7 8 31 1 5 Prostigmata(nymphs) 8 27 51 5 49 21 6 8 0 32 4 27 1 7 Tyroglyphids 1 1 ' 0 0 2 23 0 11 4 7 0 10 0 0 Enchytraeidae 7 0 0 0 9 0 0 0 2 0 5 0 1 1 Earthworms 0 0 0, 0 0 0 0 0 0 0 1 0 0 0 Myriapoda 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Coleoptera larvae 0 0 0 0 1 0 1 1 1 0 0 0 1 1 Dintera larvae 1 0 0 0 1 0 0 0 0 1 0 1 1 0 Other insects 2 0 1 1 1 0 1 1 2 0 2 1 D 1 Number of samples 8 12 16 24 16 24 16 24 8 12 16 24 8 12

C = Control A = Aldicarb treatment 184.

Table: 38

The persistence of Aldicarb and its metabolites in the Church Field plot (0-6H depth) after soil treatment on 5th May, 1970

Total Sampling date Insecticide Concentration Concentration (ppm) (ppm)

19th May Aldicarb 0.15 Aldicarb-sulphoxide 3.25 3.90 Aldicarb-sulphone 0.50 ... 22nd July .Aldicarb ND* Aldicarb-sulphoxide 0.25 0.49 --') Aldicarb-sulphone 0.24

18thSeptember Aldicarb-sulphoxide 0.12 0.40 Aldicarb-sulphone 0.28

15th November Aldicarb-sulphoxide 0.02 Aldicarb-sulphone. 0.13 0.15

* ND = Not detected 185. Table: 39

Mean population number per 0-9" sample and percentage contri- hution of species and faunal groups to total soil fauna in Church Field from May to November 1970

% contribution of each species to Mean number total population with groups A, B, C and D Control Aldicarb Control Aldicarb O. trinotatus 6.0 1.8 8.0 3.4 T. krausbaueri 56.5 55.2 74.4 85.6 Hypogastrurids 0.2 0.0 0.3 0.0 L. cyaneus 1.7 0.8 2.2 1.1 4. COLLEMBOLA F. quadrioculata 0.8 0.0 1.1 0.0 ( control 75.9%) Folsomia sp. 0.8 3.5 1.0 5.4 ( Aldicarb 64.5%) I. productus 5.5 1.4 7.3 2.1 I. thermlphila 0.5 0.4 0.7 0.7 I. viridis 3.6 1.2 4.8 1.8 Tomocerids 0.0 0.1 o.o 0.2 Symphypleona 0.15 0.2 0.2 0.3 B. Major Rhodacarids 0.4 0.1 3.7 0.3 Predatory Acari Pergamasus sp. 2.0 1.5 16.8 8.3 (control 11.9%) Other Gamasid (Aldicarb17.9%) (adults) 1.9 1 .3 15.6 7.2 Gamasid nymphs 7.6 15.0 63.9 84.1

Uropodina 1.3 1.1 13.1 6.5 3. OTHER ACARI Cryptostigmata 0.3 0.3 3.9 1.8 (control 10.1%) Prostigmata (adults) 2.2 4.5 21.8 26.5 (Aldicarb16.9%) Prostigmata (nymphs) 5.8 7.8 57.8 46.2 Tyroglyphids 0.3 3.2 3.4 18.9 Enchytraeids 1.2 0.1 55.8 10.0 D. Other Earthworms 0.1 0.0 2.3 0.0 iLve.)1,346/than Myriapoda 0.0 0.1 0.0 10.0 Collembola & Coleopterous larvae 0.2 0.1 9.3 20.0 Acari) Dipterous larvae 0.1 0.1 7.0 20.0 (Control 2.1%) (Aldicarb 0.6%) Other insects(adults)0.5 0.2 25.6 40.0 186.

Table: 40

Comparison of the mean population numbers per core between aldicarb treated and untreated areas in Church. Field from May to November (0-9" depth) 1970

Mean Population Aldicarb Population Control Aldicarb as % of control COLLEMBOLA 1553 1047 67 O. trinotatus 125 29 23 T. krausbaueri 1155 896 78 Hypogastrurids 5 0 0 . I. cyaneus 34 12 35 F. quadrioculata 17 0 0 Folsomia species 16 57 356 I. productus 113 22 19 I. thermoophila 11 7 63 I. viridis 74 19 26 Tomocerids 0 2 - Symphypleona 3 3 100 ACARI (predatory) 2+4 290 119 Rhodacarids 9 1 11 Pergamasus species 41 24 59 Other Gamasids (adults) 38 21 55 Gamasid nymphs 156 244 156 OTHER ACARI 206 275 136 Uropodina 27 18 67 Cryptostigmata 8 5 63 Prostigmata (adult) 45 73 162 Prostigmata (nymphs) 119 127 107 Tyroglyphids 7 52 743 Other inver/ebActees (other than Collembola 43 10 23 & Acari) Enchytraeidae 24 1 4 Earthworms 1 0 0 Myriapods 0 1 - Coleopterous larvae 4 2 50 Diptera larvae 3 2 67 Other insects (adults) .o 4 44 187.

(i) COLI4MBOLA

Onychlurus trinotatus

This species was the second most frequently, occurring

species constituting 8% of the total population of Collembola found during May to November, 1970 (Table 39). Mostly it was abundant in upper layers (Fig.35), although

during late spring its numbers were similar in all layers.

Three peaks indicate population built—up possibly due to

different generations and the population decreased towards

the end of autumn. After aldicarb treatment the population

was reduced considerably up to two months after treatment

but a first peak appeared in July; this indicates the

possibilities of migration into treated areas at this time.

The second peak was delayed and only 20% of insects in

comparison to control were recovered during the November

sample.

In the control areas the population of predatory

gamasid nymphs increased during August while there was a

corresponding decrease of 0. trinotatus in treated areas.

Gamasid nymphs and Pergamasus spp., were more common

during August and consequently the population of

0. trinotatus diminished. In later months the Collembola

were affected by the presence of predatory mites in treated

areas more severely than in the control. This suggests

that the decrease in population was also due to predators

(Fig.36 ), apart from the persistence of insecticide. A

77% decrease in the population was noticed during the

6 months after insecticide was applied (Table40). 188.

Tn prlimtnary 1n1,%,rt.i.too elcperimontG Pergamasus spp., were established as predators on O. trinotatus, which supports the previous statement

T. krausbaueri

This was the most abudant species of the soil fauna and the mean population calculated was 74.4% and 85.6% of the total Collembola in control and aldicarb areas respectively (Table 39). Species were extracted from all layers studied (Fig.35 ) and recoveries were 0-3", 3-6",

6-9" in order of decreasing number during May to November.

Glasgow (1939) observed similar distribution on

T. krausbaueri, in different soil layers. In treated areas the population was decreased but recolonisation was rapid and exceeded the control populations during October and November. Maddison (1969) reported upsurges during recolonisation of T. krausbaueri in zinophos treated soil.

Since T. krausbaueri was the most abudant species it was therefore considered logical to study the response of major predatory mites on the natural population balance of T. krausbaueri and the effect of aldicarb treatment.

The analysis of data revealed that the Rhodocarids,

Pergamasus spp., Gamasid adults and nymphs were principal predatory. Fluctuations in the mean population per sample are presented in Fig. 37, for T. krausbaueri and associated Mesostigmata to correlate relationship in their populations in control and aldicarb treated areas. .189.

During May the predator and prey populations were affected in a proportion similar to the control pattern when compared with the response of insecticide. June, probably due to higher temperature along with little rainfall, provided worse conditions for the oollembolan in treated areas.

Moreover, loss of moisture is reported as a factor for the increase persistent of insecticides in soil due to physical absorTtion (Edwards, 1966). A 22 decrease in the population of the species was calculated during the

6 months after insecticidal application (Table 40).

It is interesting to record that this major species was significantly diminished in treated soils sampled

15 days after the application of the chemical (Table 41).

Table: 41

Effect of aldicarb on T. krausbaueri 0-3" core 15 days after treatment

Analysis of variance table

Source of Sum of Degrees of Mean Variance ratio ) variation squares freedom square

Treatments 17400.2 1 17400.2 15.5"

Residual 20252.8 18 1125.2

Total: 37653.0 19

** Significant at 1% level 190.

Toxio motz.1.1>olitos extvctofnd frost tho 0-671 core indicate that the concentration of aldicarb was highest (3.9 ppm.) during the 3 week period after treatment (Table 38) and it appears the appropriate reason for the significant result.

Upsurge in T. krausbaueri was delayed by one month in treated areas, and it appeared in the middle of autumn; similar changes in population peak was observed in

Mesostigmata as well. Mesostigmata remained less in number after aldicarb treatment although the number of gamasid nymphs was significantly increased in August and onwards, which led to a complex interaction of pesticides on Collembola and the physiology of predators along with various unknown reactions involving the flora and organic composition of the soil concerned.

Laboratory trials on P. crassipes, reported as a gamasid predatory mite on T. krausbaueri, Sheals(1956) confirmed it a definate predator on juvenile and adult

T. krausbaueri

Hypogastrurids

This group contains hemiedaphic (Hypogastrura and

Willemia) and eduepaphic species (Friesea sp.) and

were found in low numbers. The three population peaks

during June, August and October followed by very low

densities were indicative of typical seasonal fluctuations.

Hypogastrurids were found to be highly susceptible to

aldicarb (Table 39 and Fig. 35). Complete kill of insects 191,

belonging to the family was recorded when Ethylene

Dibromide, chloropicrin and Dazomet were applied earlier at the present locality (Maddison, 1969).

Pergamasus sp., gamasid and rhodocarid predators indicated a direct correlation with increase or decrease of hypogastrurids, (Fig.38). It was noticed that Willemia anopthalma, H. armata and H. dentiylata were mainly surface types and little activity occurred in the middle layer. F. mirabillis was sub-terranean and occurred only in lowest layer. No definite relationship of Hypogastruridae numbers could be established with soil temperature and rainfall data.

L. cyaneus

Population density of this surface-type hemiedaphic collembolan increased in May and June and the population peak appeared in July. During August and September the population decreased and only three insects were extracted in September from eight samples (0-9" depth). Maximum numbers of insects were obtained from the top layer and few insects from the remaining layers. It is interesting to note that the pattern of vertical distribution was similar

to the one reported by Keiko Niijima (1971) in Asakawa

(Japan). An inspection of the numbers of L. cyaneus indicated that counts were inversely proportional to total rainfall. These Collembola showed a high sensitivity to

the carbamate insecticide, although population built-up 192. 0

ONYCHIURUS TRINOTATUS TULLI3ERGIA KRAUSBAUERI Control Treatment Treatment - Aldlcarb 2.5 I.5 • o 61 .001 • 6101 0-3" , I 6 5. 0-3" 1-0 2.0 ,coi • Gni •oG a.. 0.5 1.5

.4 0.0 1.0

3-6" •001 1.0 3-6" 2.0 -o61 •of ,q

0.5 1.5 c I

0.0 10_

6-9" 4 1) 7+ C

LEPIDOCYR TUS CYA, NEUS OG L

0-3"

1.0 3-6" 0-5

3-6" 0" 025

0.0 0.0

0.5 40 6-9"

6-96 •0 01 0.25 O•

0.0 - -I • 1--4,--r• • 0'° • • • -• F M A M J J A SO N FM A MJ J ASON 1970 1970

rig. 35. Effect of aldicarb broadcast in May 1970 on Onychiurus trinotatus, T. krausbaueri, Hypogastruas and Leyidocystus cza_nouti.

Church Field 1970. 193. 0.trInotatus

2.0 A / Aldicarb ofA • a,' Q. S. o,. .

t■1 `a o t.s . / t I . / I 0 • / II / /•, • . / / / % • / t / '. A I / N.. t /

1 I r %.

0.0 0-•-•-• -AO'

4 of

0 2.0 Control 0 -J 3' 3' 3'

%.•

3' 1.0

0.0

M J J .A S 0 N 1970 Fig. 36. The relationship between the numbers of 0. trinot atus and Gamasid nymphs in untreat(d areas. Also this col lembolan and gamasid adults,nymphs and Percramasq SD in treated areas. Church Field 1970

0. trinotatus ( 0 ) gamasid adults ( 0)

gamasid nymphs ( A ) Pergamasus sp. ( X ) Fig. T. krausbaueri 37. O t.) « 1- 0 c = 0 a I A a- ( X001)N011dlfldOd Natural population balanceofT.krausbaueri of aldicarb persistenceon these organisms and Mesostigmata (predators) andtheeffect during 1970 in lower Church Field (0-9" depth). 194. ■■• 0

0 z U 0 a. w w z N 0 195,

3.0

HYP OG ASTRUR1 DS Control

2.0

a `\

`A / 0 R 1 \ X / 1 / • 1 .0 \. / x 1 \ 1 / 1 \ 1 / 1 t, \X/ 1 % \ •A .0 % .... 0... •••" "'"' • \ • a" ..--• i • / •

\ • \

, 4444 44 0.0 a

M J J A S 0 1970

Fig. 38. The relationship between numbers of hypogastrurids

and Gamasid adults and nymphs and Pergamasus sp.

and Rhodacarids. Church Field 1970.

Hypogastrurids ( 0)

Gamasid adults ( 0)

Pergamasus sp. ( X )

Rhodacarids ( • )

Gamasid nymphs. ) 196. increased in the long run and exceeded control numbers in November. Such increase in number might be attributed to three reasons:- (1) Migration from the untreated areas.

(2) Reproductive stimulation due to the insecticide. (3) Aerial distribution of Collembola as suggested by Flower (1964) and Buahin (1965). A decrease of 65% was calculated in the treated areas, when compared with check areas (Table40). No definite predator-prey interaction could be established although the presence of general predators of Collembola might have affected the population in some ways. Bhattaoharyya (1962), established Pergamasus as a predator of the species and three species of the genus were found along with Collembola extracted.

F. quadrioculata This isotomid was characteristically a surface type species and other workers (Kiihnelt, 1961 and Buallin, 1965) observed its frequent movement up to the top two inches of the soil. Maximum population was recorded during the beginning of autumn which appeared to be the most favourable period for oviposition. Statistical analysis (Table 11a, b), of the distribution of the species indicated that it was patchy as the Heyman A was a good fit the Double Poisson was also a good fit, 0.3>00.2. Usher (1970), found that

F. auadrioculata, adults, have uniform distribution in pine forest soil. 197.

Hughes (1954)(1954) _, pointed out that F. quadrioculata may be randomly distributed. A rise in the population of predatory mi.tns during August seems to explain the lowest density. Peaks of Mesostiginata (rhodocarids, Pergamasus sp., gamasid adults and nymphs) probably induce low population dips of F. quadrioculata _ . during October and November. Populations in treated areas were partially wiped out after aldicarb treatment in May and only few insects could be screened in the whole 0-9" layer until the end of the experiment. Table 40 also indicates 100 per cent kill of the species due to insecticide. Vertical distribution

(Fig.39) was similar to that reported for L. cyaneus.

Folsomia sp.

The vertical distribution data for Folsomi- Fig.39 ) incorporates two commonly occurring species, F. candida,

F. fimetaria and a third rare species Folsomia fimetariodes.

The population showed a very good fit (0.5 >P >0.3) to the negative binomial distribution. Collembola were under the direct influence of associated predators, as revealed by the correlated rates of increase and decrease in the density of Collembola and predators in untreated and treated areas (Fig. 40). The absence of Pergamasus species• and gamasid nymphs and adults was the most likely factor for the sharp increase which occurred during October in tho middle layer of aldicarb treated soil. There was a 198. definito ind:LeAti.on thitt Polsomiart, not p.olcly 4,4111)-- terranean arthropods as they were found moving in all layers. Probably toxic metabolites of aldicarb could have leached down to deeper soil layers due to rain in May and it might have favoured insects forming their colonies in a safer zone

An overall increase of 256% for Folsomia sp.,

(Table 40) was observed during the period of the experiment.

The action of aldicarb along with predation was pronounced in June and July counts and a months delay in recolonisation occurred during late summer. It is important to record that juveniles were in the majority for the October peak in the treated areas (Fig. 41). Some of the F. ametarioides extracted from the treated areas showed abnormal mucor, 4-5 teeth in comparison with 3 teeth in normal specimens.

I. productus

This was one of the most widespread and frequently occurring species and was 5.9% of the total population of

Collombola in the control areas. Its number in .the different layers up to 9" did not vary considerably and this may have been accounted for by its sluggish movement. Presence of a peak during July and October in control and aldicarb treated areas (Fig. indicates a uniform bioocological response of the population. No apparent relationship was noticed in regard to predators extracted along with

I. productus or climatic factors. General observations indicated that seasonal population fluctuations in these 199.

Collembola and Mesoetigmata were more or loss proportional.

Recolonisation did occur after treatment, although

the species is sensitive to the insecticide, but the

buili up was not sustained (Table 39Fig.39). The population was decreased by 81% during 6 months after treatment in

the 0-9" core when compared with control data (Table 40 ).

Isotomina Vermqphila

The maximum density of this surface-type hemiedaphic species was recorded in May. Later on, the population

gradually decreased and only a few insects were found during

the autumn in the control areas. The numbers of predatory

mites reported earlier were always more than I. thermqphila in all samples in the control areas. The number of

I. thermqphila was reduced to zero during the first three

months after aldicarb treatment but the following

recolonisation numbers surpassed the control maxima in

July. Overall, aldicarb reduced the numbers of this species

by 37% (Table 40).

I. viridis

Vertical distribution revealed that this isotomid

was mainly a surface type. On only a few occasions were

insects extracted from deeper layers, otherwise the numbers

remained insignificant. Peaks occurring during studies

indicated a short life cycle of the species; peaks during

September and November were probably partially due to a 200, ISO TOM D E S PRODUCTUS FOLSOMIA SP. Control 1.5 TrelliMent .o,| AlclIcart. Treuttnnt •

1.0 P • 0 er 0.!.• 0-3" V 0.5 •0°1 00

0.0^

0.0

0.75 6-91' •001 • 1.0 0.5 6-9"

0 5 A 0-25

\\tki oo °•• 0.0 --..••""a• NY- ISOTOMMA THERMAPIIILA FOLSOMIA OUADRIOCULATA' 1.0

0-5

I N • 0 3" 0.0 % %.

3-6"

0.25

0.0

6-9" o'25

0 • 0 °' 0.0 FM AMJJ A SON FMAMJJA 501J |v70 I 9 70

••• Pic. 39. Effect of aldicarb on Isotomodenprodnctus,

op. Motomina thmeroph ila, roloomia

9undrioculota. Church Field 1970.

201.

Folsomia Sp.

2.0 a Aldicarb / A / S. / A • . 1 ■ S. / / ..% / 1 / A I • 1 ■ / % ° . / 1 / 0 . / , , 1 %A 1 .0 % / / //. X ..."."...... /# 1 // X...... ;...... ",.....„,X x 1 I / 1 I 1/ - 0.0 a 7. Ix 0 0 2.0 A Control

A /%\

s.A 0

\• 1 1.0 1 O \A .o- • .1 x

A 0.0

M J J A S 0 N 1970

Pig. 40. The relationship between the numbers of gamasid nymphs and adults and Pergamasus sp. and C Folsomia sp.in untreated and aldicarb treated areas. Church Field 1970.

Folsomia sp. ( 0 ) Gamasid adults (0)

Gamasid nymphs ( A )

Pergsmasus sp. ( X ) 202.

...... MII••••.IMII.IM■Ir.■pxipww•el•••.I.IIII.MI■+•-■•••—■-•--

Fig.41. October extract of Folsomia sp. - more juveniles present (x 10). 203. fall in the predator population. General effects of aldicarb, reported earlier on I. thermelphila, were also observed in I. viridis but the species was more than twice as susceptible as the latter (Table 40 Fig. 42). The population density during October was uniform in control and treated areas, which supports the statement regarding their short life cycle and consequent quicker recolonisation. The population build-up capacity of I. viridis may thus be considered fast.

Tomocerids

two species T. longicornis and T. minor, were the only hemiedaphic tomocerids recorded. T. minor was a rare species. They are surface-type and active Collembola,

therefore the reasons for the maxima in July (Fig. 42) and presence in treated areas (Table 37), is suspected to

be due to migration from surrounding adjacent areas. Confinement to the top layer was perhaps due to their large size (4 mm) and lack of ability to penetrate through minute soil pores. Similar comments regarding their size

were made by Karg (1961) and Sharma acid Kevan (1963).

Symphypleona Neelus minimus (Neelidae), Sminthurinus niger and

S. elegans (Sminthuridae) were only a few representative Collembola from the sub-order Symphypleona. N. minimus

was found in 3-9" soil samples while the Bminthurids were confined to 0-3". Rise in treated areas (Fig. 42 ) might

204.

ISOTOMA VIRIDIS SY MPH YPLEON A

Treatment Treatment I.5 0.5 0-3" 1 1.0 025 • /

0.5 , 0-3" / 0-0,_ — • — 1)/ )

1 0.5

ii+ 3-6" 1.0

025 oat 3-6" OG C

L 0.5

0.0 0.0

0.5 0.5 6-9"

•001 6 -9" 0.25 0.25

0.0 •- - , 00 FMAMJJ A O N FMAMJJ 0 N I 9 70 I 9 7 0

TOM OCERI DS Control Aldicarb

Treatment 0.5 0-3" • / I,'J4 025 ,

0 \ -J 0.0 FMAMJJ A S ON I970

Fig. 42. Effect. of aldicarb on Symphypleona l Isotoma viridis Tomocerids. Churchfield 1970. 205.

have occurred due to the migration from other areas

(Table 37 ) and thus escaped the toxicity of aldicarb or they are comparatively tolerant Collembola.

(ii) Major Predatory Acari

On the basis of preliminary laboratory observations,

rhodocarids, Pergamasus sp., and other gamasid adults

were considered as major predatory mites on Collembola.

Possibilities of a particular group or groups of predators

on Collembola in field conditions have been already

mentioned above.

Vertical stratification of the Acari spectrum in

different depths is indicated in Fig. 43 and seasonal

abundance and population density in relation to the

persistence of aldicarb treatment in a core of 0-9" is

shown in Fig.44. These Mesostigmata were the second major Ave.icts group after Collembola in the whole of the soil a-141,w-epeas

examined and constituted 121 of the population. A reduction

of 11.4% in the faunal contribution of Collembola and an

increase of 6% in the faunal contribution of predatory

mites, during seven months after aldicarb treatment,

supports their designation as predators (Table 39 )• Their number in the aldicarb treated areas was 19% higher

than in the control.

Some of the limiting factors on the concentration of

different mites in control and aldicarb treated area are

described below: 206.

(1) Rhodocarids

The population showed 4 maxima and 3 minima and the population peaks occurred in mid-autumn. Of the Mesostigmata

these were the more susceptible; and recolonisation took

six months. During favourable conditions, these bright pink

coloured euedaphoiwere distributed in the whole soil profile,

but mostly they were found in deep layers.

(2)Pergamasus sp.

These species are known predators on T. krausbaueri

and other Collembola (Shoals 1955 and Maddison 1969).

During present investigations they were not much affected

by the aldicarb treatment, although their population did

decrease. Population density remained similar in treated

and control areas until November when there was some

indication of an increase only in control areas. Highest

and lowest concentrations were recorded in November for

control and treated areas respectively. These mites were

mainly active near the surface and they are classified as

hemiedaphic (Karg, 1961; Wallwork, 1967; Oliver and Ryke,

1969). Young stages were found throughout the field studies

and similar observations have been reported by

Bhattacharyya (1962)n (3) Other gamasid adults

Hemiedaphic gamasids, are mostly carnivorous and prey

upon Collembola and tyroglyphidsetc., (Karg, 1961). The

population of gamasid adults reached a first peak during

May in the check areas and it was gradually decreased in 207. subtiegunnt months except in the July and September upsurges. June and August were unfavourable months. Attempts to analyse critical limiting factors, including temperature, rainfall and prey population, were not successful in examining population fluctuations.

Aldicarb caused complete destruction of these predatory mites during May but population build-up was fast and the

late summer pea 1I with the control peak (Fig. 43). Voronova (1968) also observed the complete kill of soil Acari after treatment with Sevin, a carbamate insecticide. Population in treated areas once exceeded the control population seven times during early September in 3-6" and 6-9" layers. Thus there was a spectacular recovery and some evidence of downward migration during colder months, may be suggested. The overall decrease in numbers of these

predatory mites during May and June may have been due to a combined effect of the insecticide and of the absence of

prey (Table 37). (4) Gamasid nymphs Nymphs were very active amongst the entire soil fauna studied and their movement in the soil profile was not confined to any specific depth, although population densities were greater in the middle layer (Fig. 43). A 56% population increase was calculated as a direct/indirect

effect of aldicarb treatment (Table 40). The fall in the population of nymphs during June is

comparable to adults and is probably associated with the

life-cycle. The number of these micro-arthropods was 7.6% which is next to the highest score of T. krausbaueri. 20B„

GAMSIDS CNymphs)

Treatment PERGAMASUS Sp. (Adults) 1.5 0-3"

•Aldiearb 1.0 Treatment 0-3" o .04a5

0 5_ \

0 OL

1.0

0.5

6;Q" I .5

6-Q" I.0 1.0

•ool 0.5 .os 0.5 7 pc 0.0

O RHODACARI DS (Adults) OTHER GAMSIDS (Adults)

025

0S 6-9" 1.0 6-9" • ool 4', •0 •00t I • I \ 0.25 0.5 •0 01 . N.

0 0 ••-.- 0.0 FM A M J J A S ON F MAMJ J S 0 N 1 9 70 19 70

Fig. Effect of aldicarb on Pergamasus sp. (adults), Gamasids (nymphs) Rhodocarids (adults), other Gamasids (adUlts) ghurch Field 1970. Fig. AC AR I Cpredatory) 0 44. predatory mites,in 0-9".ChurchField1970. The effectofaldice.rb onnumbersofthemajor Gamasid nymphs Rhodacarids Other Pergamasus in Gamasid adults( 209. sp.

CI+A) 901 0

( a ) ( 0) ( •) A ) 0 ( 0 1 - 1

210.

Their number was significnntly higher than all the other Mesostigmata during the 3 months after insecticidal

treatment. The fluctuations in counts of treatment numbers were out of phase with the control in the 3 - 6" layers, but outnumbered the control after September. The November

maxima in the treated area following the general downward

trend from the August maximum is very curious and reasons

for the observation are lacking.

(iii) Other Acari

(1) Uropodina

Uropods were not found during spring. By the middle

of summer they began to appear and their highest density was

approached in August. A second peak occurred in October

when mites were confined in the surface layer only.

The population was unaffected after treatment and numbers

equalled the control values in all layers (Fig. 45). There

was a marked fall in population numbers in September.

(2))Cryptostigmata .

The Cryptostigmata was the most poorly represented

group of mites'.in the fauna, (Table 37) and only

P punctam and C gracilis were observed in significant

numbers. Poor yield in arable land has been also recorded

by other workers (Maddison, 1969; Wallwork, 1970). 211.

The statistical tests on one of the species, namely

P. pulotua, showed a patchy distribution (Tables 118x., b).

These mites feed on fungi, algae and leaf etc., therefore their abundance in the surface layer was quite reasonable.

Their seasonal abundance was not fully correlated with

climatic factors and maxima indicated short life span.

These micro-arthropods were very sensitive to aldicarb and

population density did not recover after the treatment

until October. The pattern of vertical distribution (Fig. 46)

indicates its relative sensitivity to toxic residues of

aldicarb metabolites in all soil layers.

(3) Prostigmata

Order Prostigmata constitues one of the

major arthropods of soil fauna. Pygmephorus sp.

was the most abundant species followed by Balaustium

florale and Eupodes sp. Raphignathus sp. and Tarsonemoiedes sp.

were less common and individuals of Microtrombidium sp.,

Tydeus sp. and Scutacarus sp. were found only on a few

occasions. Some species of the order are mainly

mycetophagous while Bdellidae feed on pollen (Evans,

et. al., 1961); while other species had been reported

as predators (Wallwork, 1967). Direct effects of the

Prostigmata predators on Collembola were not evident,

therefore only mean population fluctuations in the group as

a whole are examined (Fig. 454). The relative distributions

of the adult in the soil profile were not stable, but

nymphs were mostly more abundant in the top layer. 212.

These mpecies were found in abundance during May to August, and in October nymph densities wore higher than adult densities, although the maxima of adults and nymphs were synchronised. An October maximum in the Prostigmata was also reported by Evans et. al., (1961) in samples of soil from Bedfordshire. The population of nymphs was found to be slightly affected up to four months after insecticidal treatment.

The populations of adults and nymphs in the treated areas were greater than the control during September -

November. This affect may be due to:

(a) The Prostigmata are reported as saprophagous

Acari (Evans et. al., 1961; Oliver and Ryke, 1969) which feed on dead organic matter. There was an abundance of two of the saprophagous Acari namely Pygmephorus sp., and

Eupodes sp., probably due to the availability of dead organic matter in the treated field e.g., unharvested potatoes, of dying or decaying dead fauna or flora in soil pores, due to the toxic effects of carbamate and seasonal change.

(b) Possibly stimulatory effect of the insecticide on the fecundity of the species concerned.

(4) Astigmata Only three species of the family Tyroglyphidae were found. They are reported to feed on fungal and plant detritus, and liquified products of putrification process

(Karel 1963). Their numbers in the control areas were low 213k,

TYROGLYPHIOS PROSTIGMATA [Nymphs) • • Control 1.5 Treatment Treatment •_ _ -. Aldicarb tt .001 .0; :65)1 — 6-3" 10 / I tt \ r • S \ 1 0 5- 1 1 1 / 1r 00

1.0_ .

0.5 3-6"

0.0

2.0-

1.5

-001 1.0_ 1.0 .001 . , 6-9" °1 t 3 \\ 6 0.5 . ., ik • o \ n •,... ri i tt 6,-.4--... x 0 0_ —4 0.0_ PROSTIGMATA (Adults)

.00f A 0-3" /

3-6" 1.0 _ 0 /

0.5 •

00`

1.0 6-9" col 6-9" 025 0.5 '00 0 0 [ • „ -. •n , O 0 F ha A M .1 J A S 0 N FM A M J J A S O N 1970 1970

Fig, 45. Effect of aldicarb on Tyroglyphids 1 Prostigmata

(nymphs ), Uropodina, Prostigmata (adults)) Church Field 1970. 214.

3.0

2.0

0.0

M J J A 0 N 1970

Fig. 45a. The effect of aldicarb on numbers of Prostigmata

adults and nymphs in 0-9". Church Field 1970. Adults 0..:1' Control Nymphs 4---11

Adults O„ O. Aldicarb Nymphs A= 215. with a population peak during July in the 0-3" layer and a second peak in all layers in August to September. The population. was slightly affected for a month after aldicarb treatment but during July and August it was increased

10 x 11x respectively in comparison to the control population. In seven months there was an overall 643% increase in the mite population after aldicarb treatment

(Table 40). Most probably the increase of putrifying organic matter after insecticidal treatment might have enhanced fungal growth and therefore increase of food seemed to be the reason for such a Mctacular population boom.

(iv) Other invertebrates

(1) Enchytraeidae

The biomass extracted from the Church Field soil contained one per cent of enchytraeids. Achaeta bohemica and Henlea perpusilla and other Henlea sp. recorded were mainly young and immature stages.

Reynolds (1943) studied the life-cycle of some enchytraeids and

18°C. to be the optimum temperature. In present field studies the maxima of the species is considered to be due to the favourable temperatures in the spring to autumn periods.

Seasonal trends in the population density, as reported by

O'Conner (1967), is also evident from May to July and October peaks. Springett et al (1970) studied in detail the seasonal populations of twenty one species of enchytraeids which generally had summer maxima 216. and winter mad early spring minima in "Mull" type soils. The maxima and minima, described here (Fig. 46), differ from Springett findings. No specimens were found in the 6-9" layer and only a few were recorded from 3-6", therefore mean population density of only the 0-6" layer is recorded

(Fig. 46 ). These worms appear to be very sensitive to aldicarb and present observations showed a 96% decrease in their population after aldicarb treatment (Table 40). Gamasid mites occasionally prey on small enchytraeids

(Ktihnelt, 1961; Wzattacharyya, 1962; Karg, 1963; Maddison, 1969) and this could be an additional factor hindering their recovery. Voronova (1968) observed high mortality of enchytraeids after soil treatment, with Sevin. Since the enchytraeids are litter destroyers (Table 40 ), soil fertility could be severly affected as a side effect of aldicarb treatment. (2) Earthworms Young worms of the shallow-living species ALL0Lob6pApp.4 caliginosa, A. chlorotica and A. rosea were also extracted a few times from the field. Although their number was low, due to the methods of sampling and extraction there is some

evidence that there was adverse effect of the carbamate pesticide on them (Tables 37, 39, 40).

(3) Myriapods Myriapods of the Pauropoda, Symphyla and Chilopoda were extracted. It was necessary to group the few

individuals collected (Fig. 1+6 ). 217.

The maximum number of myriapods were found during spring and later on their numbers became sporadic. Effects of aldioarb could not be isolated from population counts of control and untreated areas. (4) Coleopterous larvae The major larvae collected were staphylinids and a few were of carabids and some coccinellids. General observations on the effect of aldicarb on these insects indicate that their populations were not significantly affected (Fig. 46 ). Counts during August and November indicate that probably due to the increase of mites population in treated areas, some predatory larvae of Staphylinidae and Carabidae (Schaller, 1949 and Kiihnelt, 1961) flourished more than in the control. Preliminary laboratory observations revealed that A. bilineata (Staphylinidae) may feed on T. krausbaueri. (5) Dipterous larvae The number of larvae reported in the fauna list were pooled for the entire 0-91' depth (Fig. 46 ). Population densities were decreased during three months after insecticidal application and thereafter a steady increase was observed until October. Edwards, (1965) cited examples of increase in Dipterous larvae, when predators were killed by pesticides. Although predator and prey relationship could not be

established its possibilities cannot be ignored, in view of Edward's report, and significant population increase is evident (Table 37). During November, due to low temperatures,

most larvae were expected to move into deeper layers of soil. 210.

In the treated area residues of aldicarb metabolites were present (Table 38), therefore, presumably some sensitive sluggish species died while active species might have escaped the toxic effects. (6) Other Insecti6(adult)

Because of the number of adults of various insect species found when Collembola were extracted from the field samples, it was thought advisable to compare the count of miscellaneous adult insects in control and treated Areas, in order to ascertain the effect of carbamate pesticide on their numbers. Mean population counts (Fig. 46) indicate three maxima in the fauna each during spring, summer and autumn. These fluctuations might have occurred due to different life-cycles for different species in the control areas. The population was completely erradicated after aldicarb application, but adults began to appear in low numbers during June to

October. The peek of control and treatment did not sychronise and, moreover, their arrangement was found opposite to each other (Fig. 46). This suggests that there might be a delay of one month in the life-cycle in the treated areas. The November increase in treated populations was parallel to control which indicated tolerance of the adultsto the level of toxic residue

(Table 38) and/or release from the predatory population, as most other fauna were diminished at this time. A comprehensive account of the feeding habits of Coleoptera,

Diptera and other insects is given by Raw, (1967) but no definite correlation could be established in the present studies. 219.

CRYPT CST IGMATA

Treatment Control 2.0 AI dlcarb

ENCHYTRAEI DS 1.5

0-3" Treatment I.0

0-6"

0.0 / t

0.251._ • cb ei 3 — 6" •o f MY RI 0 PODS 0.0 •

0.25

7. ivx 0.0

O OTHER IN SECTS CAdults ) O 0-9"

0. 5

0.25

0.0 COLEOPTEROUS LARVAE DIPTEROUS LARVAE

0-5 0-9e 0. 5

0.25 0.25

00 , • 0.0 FM AMJJ A S 0 N FM AMJ JASON 19 70 1974

Fig. 46. Effect of aldicarb on Cryptostigmata, Enchytraeids, other Insect adults, Myriapods,

Dipterous larvae, and Coleopterous larvae.

Church Field 1970. 220,

3. Effect of cultivation on the untreated population of soil fauna

The population data of the 1969 untreated plots was compared with those of 1970 (Table 42). The field during

1969 was cultivated and the potato crop was sown. The field was not disturbed during 1970 in order to evaluate the effect of cultural practices. Changes in the census of 1969 and 1970 may not be fully attributed to lack of cultural operations, as variations in climatic factors such as temperature and rainfall are bound to exert considerable influence on the fauna. It may be pointed out that during 1970 Collembola,

Acari, and other miscellaneous fauna were decreased, 59.1%, 25.7% and 14.7% respectively, in comparison to the 1969 census. These changes might have been caused by the lack of ploughing, rotovation, fertilizers application and unharvested crop of potatoes. Onychiuridae, Lepidocyritadae and Isotomidae were increased while other Collembola, including Tullberginae, decreased. Mites other than the Cryptostigmata and Prostigmata were decreased. Also other insects were increased.

Kavan (1955)2 Naglitsch and Steinbranner (193) and Christiansen(1964) suggested irregular effects of cultivation. Schalk (1968) reported no effect while Curry (1970) found significant population increases due to cultivation. Present findings confirm the opinion of former authors. Edwards & Lofty (1969) also found that fertilizer application increased food and consequently increased the fauna. Increase in fauna during 1969, there-. fore, could have been caused by the fertilizer application. 221.

Table: 42

Comparison of the mean number of individuals per 0-6,, core in untreated soil during 1969 & 1970, June - November at Church Field

Mean Population 1970 as percentage 1969 1970 of 1969

Collembola 440.0 180.0 40.9 Onychiuridae 10.2 13.2 129.4 Tullberginae 404.7 134.8 33.3 Lepidocyritadae 3.7 4.5 121.6 Isotomidae 19,7 27.3 138.6 Symphypleona 1.8 0.0 0.0 Acari 50.2 37.3 74.3 Mesostigmata 38.2 18.0 47.1 Cryptostigmata 0.5 0.7 14o.0 Prostigmata 10.3 18.0 174.8 Astigmata 1,2 0.7 58.3 Miscellaneous 6.8 5.8 85.3 _Mrecta 2.3 3.0 130.4 Other t livet, tehit,tteS 4.5 3.0 66.7 Total soil fauna 497.0 223.0 44.9 222-.

4. Factors affecting persistence of aldicarb Persistence of aldicarb during 1969 and 1970 can be compared (Table 38 and Appendix Table 6). A comparison of fauna extracted during both years is also made and results are presented in Table 43. Degradation of aldicarb was different in the two years. Skrentny (1970) cited that aldicarb was more rapidly oxidized to sulphone than in 1969, at Church Field plot. He reported further that there differences in weather conditions such as the temperature, rainfall, and also in the microbiological population, and the amounts of organic material in the soil. All these factors were considered responsible for the degradation of aldicarb to its metabolites. The comparison of fauna revealed that most of the soil animals were less affected during 1970 and it is comparable with the chemical estimates. Significant increases were observed in Symphypleona, Prostigmata and Astigmata and Mesostigmata. Appropriate reasons are covered earlier in the results. Aldicarb appeared to be less persistent in uncultivated soil than in ploughed, rotovated and fertilizer - applied soil.

Present studies provided an opportunity to analyse some of the factors responsible for the persistence of aldicarb in sandy loam soil. It appeared that aldicarb was more persistent in the undisturbed. 223.

Table: 43

The changes in soil fauna in sandy soil after aldicarb treatment (0-6" depth) comparison of 1969 with 1970 June - November (percentage of control)

1969* 1970*

Onychiuridae 14.7 30.3 Tullberginae 70.0 78.3 Lepidocyrtidae 18.9 28.9 Isotomidae 11.2 59.3

Symphypleona 0.0 ONO Mesostigmata 27.5 141.7 Cryptostigmata 60.0 100.0 Prostigmata 75.7 111.1 Astigmata 25.0 828.6 craP, uInsecta 73.9 40.0 Other in-fertbmoLlits 73.3 10.0

Note: Assessment based on mean population of treated and

control plot. * 1969 - Rotivation, application of fertilizers and sowing of potato crop. * 1970 - Unharvested potato undisturbed soil 224..

and non-planted soil. Increase in peruistazcs of

aldicarb in cultivated soil seems to be due to its

different physical adsorption of toxic molecules or

competitiveness with differential water control

mechanism of a ploughed field. Edwards and Lofty (1969)

rotovated the soil sprayed with insecticide and

concluded that the persistence depends upon the fact of

how deeply they are mixed in the soil. Clark (1967)

reported that the biological activities of the organisms are usually higher in the top 0-3" layer. Therefore such

stability of soil profile is in existence, hence the

microbiological population in this layer may contribute

to the faster rate of degralation of the chemical in

the sandy acid Church Field soil. Wheatley et. al.,

(1962) reported similar results for aldrin and dieldrin

in sandy loam soil. Lichtenstein and Polivka (1959),

and Lichtenstein et. al., (1961), confirmed that the

degradation of pesticides is affected by different

cultivation practices.

Present findings indicate that the insecticide was more persistent in rotovated and ploughed fields;

however, there may be some unknown factors related to

fertilizer applications. 225.

5. Rffect of snow on the soil fauna

After extraction of the soil fauna from control plot samples (0-•3") at Church Field in February, 1970, the field was covered with a heavy layer of snow which stayed for a week followed by sub-zero air temperatures. A second extraction was carried out after the snow thawed,to observe the effect of snow on the soil-dwelling micro-arthropods. Fig.47 represents the mean (log x + 1) population of the entire fauna. Each point Indic,-Ites

each species or group. It is evident that the 0-3"

population of soil organisms was affected adversely by the snow and following the snow the whole fauna was reduced to 47.7% of the numbers before snow. Generally

mites were found more tolerant than Collembola. Kilhnelt (1961) gave similar accounts of the tolerance of mites to low temperatures. However, F.que.driocu/ataand I. productus did show an increase in numbers. The geographical distribution of F. quadriaculatareveals that the species occurs even in arctic Sweden, (Agrell, 1942); possibly indicating a higher tolerance to low temperatures. I. productus and gamasids usually lay their eggs in deeper layers but they were extracted in abundance in 0-3" cores after snow was melted. This could be due to the

filling of the air spaces of the lower layers of soil by water and forcing some movement upwards through the profile.

A waterlogged field may give rise to swarming of some Collembola and Latzol (1907), described such increases in

TOTAL REDUCTION = 47.7

• • • • • • MAR. 1.• t • " ..E______SNOW o FEB.1 08 ICIB 0 8 o 0 0 ce

0 • 5 1.0 1.5 2.0 LOG (x-1- I ) 227.

Colloabola Aft.,ar snow. In vim of OlusgoIgts findings (1939), it may be suggested that nom species of Collembola may die due to waterlogging, or to the lack of oxygen in soil cavities.

Unfortunately the sampling in February was restricted to 0-3" to gain information on the form of the distribution of the soil fauna and the vertical distribution over 0-9" therefore cannot be compared with the

March samples. 228;

15 DISCUSSION

Overall,Coilebele wore decreased and Acarina

increased 6 months after aldicarb soil application (rable 40).

The untreated population of O. trinotatus

in 0-3" (Fig. 35) showed a maximum during May, 1970. Glasgow, in 1939, found similar peaks in Onvchiurus

species and mentioned migration as a possible reason. Predation of O. trinotatus by Pergamasus species

observed during current studies was also reported

previously by Kahnelt (1961) and Maddison (1969).

The species showed a high sensitivity to aldicarb.

The many factors producing the seasonal abundance of T. krausbaueri and predatory mites in

control and aldicarb treated areas were found difficult to isolate. Maddison (1969) reported

reproductive stimulation due to soil application of

other pesticides on T. krausbaueri but this was difficult to detect from current results. Seasonal

peaks observed during current experimentation were not comparable to the findings of Maddison, possibly

due to climatic factors and the condition of the soil.

I'Iaddison further reported that the adults of 2. crassipes feed on the various life-stages of

T. krausbaueri and this may be one reason for the

decrease in population during 1970 compared with

7969 (Table 42). 229.

In preliminary experiments, during the current studies, it was established that the p-cdatory Mesostigmata,

PerEamsus crassipes and staphilinid adults feed on T. krausbaueri which was the most abundant species of the soil fauna and the mean population calculated was 74.4% and 85.6% of the total Collembola in control and aldicarb respectively. The response of major predatory mites on the natural balance of T. krausbaueri and the effect of aldicarb treatment suggested that rhodocarids, Pergamasus spp. gamasid adults and nymphs were princi*7 predators. Sheals (1956) and Edwards (1965a), reported that after

DDT application the number of Collembola greatly increased while predatory mites decreased. Such effects were attributed to the reduction in numbers of predatory mites, particularly the Mesostigmata. Edwards et. al., (1967), reported increases of Collembola after application of the organophosphorus insecticides; trombidiform and oribatid mites also increased. The increases were attributed to the destruction of predators, particularly the gamasid mites. Gamasid mites occasionally prey on small enchytraeids (KUhnelt, 1961 ;Bhatts.charyya 1962; Karg, 1963 and Maddison, 1969), such a relationship might have contributed to the increase of Enchytraelaae after phorate and menazon treatment reported by Way and Scopes, (1968), following a reduction in predatory mites. 230.

The extracted fauna also contained staphylinids which, in preliminary laboratory experiments, were found to be predators

upon T. krausbaueri. They are general predators on Collembola and nematodes (Kuhnelt, 1961; Choudhari, 1962) and thus there may

be some action by the staphylinids on the soil fauna.

Decrease of T. krausbaueri in early winter is also related to their life history as they do not lay eggs after October (Hale, 1965).

Various reasons for the patterns of vertical distribution of subterranean micro-arthropods were critically discussed by Dhillon and Gibson (1962). During the present sampling more pore space in the sandy loam soil seems to be the most logical reason for the movement of T. krausbaueri into deeper layers. The 20% increase in predators (Table 40) might have been due to effective predation as most of the predatory

Mesostigmata are well distributed throughout the soil profile

(Wallwork, 1967).

The population peak of H. denticulata was observed by Hale (1965)

during the same month as reported here and he points out that,these insects oviposit during their population maximum. Spring and autumn peaks recorded by Maddison (1968) were observed in 1.969

but probably because of differences in weather condition were not

observed in 1970. 231.

On the basis of :lorphological characteristics noul 7De eategclised under euedaphon

(Christiansen, 1964, his Table 1) and they should occur only in deeper layers. However present firldings indicate that iftywa-sas not confined to the ecological group of Christiansen. 1=arg (1961) reported VeiLaia 1;116morensia as a specific predator on F. firaetaria; and the present extraction produced both arthropods. Decrease in the population of rhociocarids caused an increase in the population of F. candida after DDT application (Edwards, 1969) Adult predators rel)orted by Maddison (1969) were also

decreased in aldicarb treated areas. A 89% decrease

in the population of the same predators (similar to

that reported by Edwards and naddison) was observed

in the fauna (Table 40) which could have been

responsible for the increase in the Folsomia population (Fig. 39). Badmin (1970) found abnormalities in parts of

the mouth, antennae, etc., of Diptera treated with

chemosterilants. The type of abnormalities observed in the mucor of F. MNAAAnt,oidas. indicate the possibility of some interference by aldicarb at gene

level - perhaps a mutugen:ic effect. nacnillan (1969) also found a nay population

peak in I. thermciphila and also indicated that the

greatest variation occurred in the same month. 232.

Maddison (1969) found that the species was a prey of

Pergamasup sp., but the population figures of both from current extractions do not give positive support to his findings. Similar observations were recorded in

Symphypleone. Maddison reported spring/autumn upsurges in the population of Svmphypleona while. only a spring peak WiaE evicler;t :in the present studis, That Acari prey on Collenibola has been reported by various workers (Karg, 1961; Wallworh, 1967;

Oliver and Ryke, 1969; Maddison, 1969; Usher, 1971)

and this relationship was confirmed in present studies. Rhodacarellus silesiams was described as a predatory mite by Edwards (1969). Webb (1970) indicated that most of the predatory mites (Uesostigmata) have higher metabolic rates (Oxygen-consumption) than non-predators of the Acari and stated that the seasonal

population fluctuation of R. roseus were directly related to the metabolic rate. Thus, in the present

studies the rhodacarids maxima might have been due to

their higher metabolic rate as other interpretations

do not appear to be feasible.

The population peaks and vertical distribution

of rhodacarids observed by Dhillon and Gibson (1962)

were not identical to present findings. Such

discrepancies are not uncommon according to reasons

illustrated by Macfadyeal (1952) and Joose (1969). Tic, :14-kci•oar-in iu Folsomia sp., was probably due to

the decrease in I' . craao.k?es (Maddison 1969). This

parasitic mite was described as a predator on

isotomids by Sharma and Y:evan (l963). The population of gamasid nymphs was apparently

not affected by the aldicarb treatment and a possible reason might be their small size adding efficiency to their movement in smaller soil pores thus avoiding

their contact with the insecticides to the same degree

as the adults. Edwards (1969) pointed out that the

smaller the animal the smaller the proportion of its living space that will be contaminated, and the better its chance of survival, which supports the present

observation.

Records of early maxima in Propodipa and Cryptostimaata observed by liaddison (1969), were

confirmed by the present studies. Evans (1955),

pointed out that the population peahs of Acari differ

according to their reproductive cycle. Therefore it

may be suggested that change in the population peaks

for aldicarb treated areas might be associated with

the physiology of the arthropods. Voronova (1968)

observed a decrease in Cryptostifmata after Sevin

(a carbamate) application and a similar response by

the group was observed after aldicarb treatment. Curry (1970) noticed a similar effect by the herbicides Paraquot and Ealapon on the population of Cryptostigmata. 234„

During 1970, after the a7Tplicatton of aldicarb, docrease in the 1.0SOS“ornatta -,yam oberved and this was probably a contributory cause of the increase in

Prostigmata numbers (Karg 1961). The increase in the Prostigmata was then due to changes ( dwards, 1969 ) in the natural balance of Acari and Collembola caused by residues. MacMillan (1969) shows a variation in the number of some Prostigmata in New Sealand pastures. Current population peaks are not in agreement with those of MacMillan, probably because of differences in soil characteristics and climatic conditions. Patchy distribution(Table11a,b),stimulation of oviposition, excess of pollen grains during Hay, or decrease in competition all seem to be possible reasons for higher populations recorded for nya:phs of the Prostigmata after aldicarb application.

Similarly the population increase of Astigmata may have followe:: the reduction in Hesostigmata predators (Karg, 1963). Maddison (1969) established the predator/prey relationship of Perx,amasus crassipes on tyroglyphid mites. aame, Oardialdne proy on opiodapio and homi-odaphic Collombola and on other animals near tho surface (Critchley, 1968)0 The Colooptra.population uns 11,011red. in troetod areas after oldidarT),- 5,y42,3A04.1tIom (Tnblo 40). Thk.rc_ shay tIttorttortikeizaterection of rover“. natieS corabids N./0.th other ar474=npada fotnd in. thaoetudy 235. SECTION V. GENERAL DISCUSSION

It is a common practice to use pesticides for the control of crop pests. The application of such pesticides should only be when assessments indicate potential damage at economic levels. Their use is probably associated with undesirable side effects on other fauna particularly since few of those in current use are selective in their action and limited to the target pest. The side effects can upset the natural balance of organisms in the environment possibly leading to upsurges of hitherto uneconomic pests by the removal of competing, or parasitic and predatory species.

In addition the side effects of soil applied insecticides, might lead to the destruction of beneficaial organisms which are essential for soil fertility, e.g. organisms responsible for the breakdown of organic matter, and perhaps for soil structure, for example maintaining soil aeration and continuous mixing of the soil. To overcome this problem integrated control and rational control measures can be adopted. An essential part of such programmes is prior knowledge of the effects of such pesticides on fauna other than the target pests.

The previous sections describe an attempt to evaluate some of the responses of soil fauna to two soil applied systemic insecticides,I iinophod and aldicarb in two soil types, sandy and clay. The fauna in total were considered but particular attention was given to estimate the variations in numbers of Collembola vertically and horizontally. 236.

Also the meteorological factors have been interpreted whenever it was possible in discuss" the results. Factors affecting persistence (Edwards 1964) were taken into consideration in discussing some of the findings. Critical limiting factors (Oliver and Rykel 1969) were used to explain the fauna composition, seasonal abundance and population density.

Generally speaking, Collembola are the dominant group of the fauna, therefore, can be considered as indicators of the spatial and temporal distribution in the experimental plots. It was shown (p. 38) that the faunal density in the sandy soiluvz about 1.77 of that in the clay soil.

Some factors such as soil structure, different pH levels, clay content, and sandy content, in addition to other chemical properties of the two different types of soil may lead to such differences in the population densities of the fauna in these contrasting soil type3. Collembola are less abundant in cultivated soils than in forest soils

(Kevan,1962).

Extraction after rain gave poor yields Of springtails, which indicates that they prefer to remain in the air spaces in the soil (Kiihnelt, 1961). Therefore differences in the

numbers . the species of Collembola, Acari and other mvefTebmefes ap-thpercift in an acid, sandy soil and alkaline, clay soil are explicable•in terms of their physical characters.

It is well known that Collembola tend to form aggregations, therefore, the statistical comparisons of 237.

population densities of the more abundant Collembola and

Acarina (Tables 11a, b) mostly fitted the negative binomial

series. In all cases the coefficient of dispersion was

greater than unity, indicating that the distribution of

the species studied was statistically overdispersed, that is spatially underdispevsed. The comprehensive work done

by other workers supports the present findings (1). 47).

Aggregation of Collembola could arise from the forma-

tion of egg clusters, and in such cases the slow dispersion

of individuals would preserve the aggregations of particular

growth stages of more uniform age within the life cycle.

Aggregation may also be attributed to a gregarious instinct.

The food-seeking instinct is also considered a third

possibility of aggregation. Hale (1967) suggested that

aggregations could arise from egg batches, gregariousness,

or the coming together of individuals at a food source.

The sizes of aggregates have been estimated by Glasgow (1939)

and ranged between 3-12 inches in diameter.

Attempts were made to correlate the density of

populationsand the organic matter in the core. Results

revealed by finding the specific gravity of a.. soil sample

as a whole, including all the organic and inorganic consti-

tuents, suggested a significant negative correlation

between faunal deity and the specific gravity of soil

((Table 22). Also clearly bulk density increased with

depth of sampling and numbers of T. krausbaueri showed a

corresponding decrease. 238,

Butcher et. al., (1971) have reported that

edaphic factors of the soil make an impact on Collembola

and acarina but found that the effects of soil temperature,

humidity, salinity, etc., were difficult to separate from each other.

Availability of food, sothmoisture, organic matter

content, soil microbial activity, range of pH of the soils,

structure, and temperature could contribute towards niche

diversification in the soil-dwelling micro-organisms. For

example the significance of water content for soil fauna

has been well documented (Davies, 1928; Agrell, 1941;

Murphy; 1955; Tischler, 1955 and Hale, 1963). Ashraf (1969) and Wallace (1967) stated that the structure and pH of

the substrate may promote or inhibit oviposition by

certain. Collembola species.

The vertical distribution of the soil •fauna indicates that

they can be divided into ecological groups such as

•euedaphic species confined to deeper soil layers and

hemiedaphic species mostly living in upper layers.

Collembola such as Tullbergia kraUsbaueril Isotomodes productus,

t5nychiurus sp. and Folsomia sp. indicate an abundance in deeper

mineral layers while others, for example, Isotoma viridis,

I. thermaphila and a few species of Sminthuridae are present

mainly in the 0-3" layer, Similarly Acarina, such as

Parasitidae, uropods and some species of Prostigmata were

active near the surface, while the rhodacarids were found

deep in the soil. 239.

Most of the soil fauna is interdependent. Fungi, algae, decaying organic matter are important food reservoirs for Collembola and non-predatory mites. Gamasids not only eat Collembola, but other living organisms such as other mites, nematodes and enchytraeids (Heungens 1968).

The studies of culturing media showed that abundance of mucoraceous fungus (Mucor sp.) favoured the breeding of T. krasubaueri. Folsomia sip: showed a similar response in the presence of Penicillium sp. and Fusarium culmorum.

However, an analysis of gut contents indicated some field species are not at all fastidious in their choice of food; some favour fungus mycelia or micro-organisms while others feed on decaying leaves, pollen grains, spores, etc.

However, the present evidence is in agreement with other workers who stated that fungi are essential parts of the diet.

The inter-relationships between the soil organisms are not fully investigated. Predation is on,A such relationship between two species of such a kind that, like competition for food, it may threaten the survival of one of the two species populations concerned. The results have demonstrated that when the chemicals were applied, the population of predatory mites were reduced which was followed by an upsurge in other groups, such as Folsomia sp.

T. krausbaueri, Astigmata, Uropodina and Prostigmata.

Obviously these upsurges could only occur when toxic residues were utsublethal concentrations. 240.

It seems that the fauna composition is subjected to various interactions, for example, between the predatory mites and Collembola and non-predatory mites, and the activities of Carabidae on Collembola and other animals.

The full prey range of predatory mites and other soil predators is still not yet known nor the preferences for particular food species. The predator and prey species will co-exist under natural condition with numbers classically fluctuating around on equilibrium. When a toxic chemical is applied this natural balance is upset since some animals will be poisoned while others may escape the zone of toxicity or are able to reduce the toxic metabolites of the chemical concerned to non-toxic levels. There is some evidence that sublethal doses of the chemicals may act as a stimulant of reproduction. Perhaps the quick recoveries of springtails and mites and other arthropods in the present studies demonstrate some of the ponsil litiFr dentioned above. These do not exclude the possibility that species may develop resistance to the chemicals applied.

The presence of toxic residues was confirmed by the destruction of soil arthropods. Proportional recoveries of fauna were not wholly representative of the toxic quantities available in the soil. There are inherent differences in the susceptibility of Afferent species to chemicals. The responses of the fauna to residues in the field is further modified by the interaction between predators and prey. Thus because of the faunal interactions, comparisons of control and treated plots do 21+1. not civo trur- values for tolerances and susceptibi1ities

but to balance this laborettory bio-assays cannot give

accurate data for the full responses by fauna in the field.

Direct and residual effects of insecticides on

Collembola, and Acari in the two soil types are not only

different due to the differences in their susceptibilities,

but also to the inherent soil type differences in faunistic composition (Table 18); such differences in composition

obviously effect their recolonisation capabilitites. Thus

there is a combination of biological and chemical features

which are difficult to separate. Salient features include,

different rates of movements of soil animals in the

available pore space of the soil concerned; contact and

fumigant action of insecticides; food of predatory mites;

soil pH, moisture content, and flora coverage.

One factor in the interaction chain which has been

excluded to date is that predators are not only exposed to

the direct hazards of the chemical in the soil around them

but also to quantities taken up in their food. In the

long run these effects could be detrimental to the control

programme.

There is no surprise in postulating that soil

insecticides can affect predator-prey relationships in soil

and this may enhance damage by the pest (Ulm, 1958;

Coaker and Williams, 1962). It was found difficult to

correlate the complex interactions of various soil

animals, due to the scarcity of knowledge on their biology. 2k2.

In view of meagre knowlodgo about oconom-Lo importanoo of soil organisms the statement of Ghilarov (1965), that:

"a high natural fertility of the soil usually depends more on the rate of turnover than on a rich supply of the mineral nutrients of the plants; soil animals being an obligatory link in this turnover", appears mere authentic. But the obligatory link of soil animals is highly complex for linking with the net results of pesticide residues in soil.

Some instances are known where insecticides or their residues in soil had proved lethal to beneficial arthropods

(Coaker et. al., 1963; Wright, 1965; Edwards,

1969, 1970). Therefore, it may be suggested that the persistence of insecticide may be difficult to consider useful due to the bio-complex of soil-dwelling organisms.

However, future laboratory trials can screen selective insecticides which may prove to have less dangerous side effects and endanger the economic value of contro' operations.

Factors affecting persistence of aldicarb are not fully known apart from the reasons mentioned earlier. How residual products of aldicarb are attacked by micro- organisms and their effect on the absorption of toxic molecules in the soil remains to be fully investigated before the persistence of carbamate can be precisely defined. fon Walker (1967) has also emphasised the need of investigation into the effects of micro-organisms in detoxifying plant protoction chemicals,

Census data of the whole group of soil - inhabiting micro-arthropods is insufficient to enable the interpretation of their association with any unequivocal accuracy (MacMillan, 1969). It is realised that without

detailed ecological information it may be difficult to interpret the various reactions and interactions of soil organisms in relation to persistent toxic chemicals. 21[4.

SUMMAR:Y During the period 1968 to 1970 a comparison was

made of the effects on soil fauna of two soil applied systemic insecticides, iinophos and aldicarb broadcast on

the arable acid sandy soil of Church Field at Imperial

College, Field Station and the alkaline clay soil of

High Field at the Grassland. Research Institute. In 1970

only the effects of aldicarb were studied at Church Field.

1968-70

1. Sampling 11" cores was found more satisfactory than

3" cores for studying vertical distribution of the fauna

and for their extraction in a 'high gradient' extractor

(Nacfadyen, 1961 ). Extraction was specially improved for

clay soils and where stones were common.

The efficiency of extraction for 11" cores was 83%

compared with 67% for 3" cores based on residual extractions

by flotation. The time of extraction was decreased

from 12 days for 3" cores to 7 days for 14z"1 cores.

2. Collembola was the dominant group of soil fauna,

with TullberrPia krausbaneri the major species represented.

3. The vertical distribution of the soil fauna showed that

T. krausbaueri, Isotomodes_yroductus2 Onychiurus sp.

and Folsomia sp. are euedaphic. Isotoma viridis, I.

thermuphila and a few species of Sminthuridae, Lepidocertidae,-

and Tomoceridae are hemiedaphic. Of the Acarina the Parasitidae,

Uropodina and some species of Prostiq:mata are nemiedphic

while the Rhodacaridae are euedaphic. 245.

4. The faunal density in the sandy soil was greater than for the clay soil. The difference was attributed to such factors as soil structure, pH level, clay content and sand content. The species compositions of the two soils were also different.

5. The role of meteorological factors have been interpreted whenever possible in discussing the results.

6. The distribution of individual species suggest that the soil Collembola and Acarina form aggregations. In most cases studied the variance/mean ratio was greater than unity, that is the distribution was statistically overdispersed, and thus individuals were spatially underdispersed. The negative binomial described most of the distribution data. Aggregation of Collembola could be explained by the production of egg clusters, a gregarious instinct, or by aggregation at non-random food sources.

7. The seasonal distribution suggest that in the areas examined the maximum and minimum densities of Collembola occur in winter and summer respectively. Collembola are normally more abundant in the upper layers of soil. The vertical distribution of Collembola numbers and of soil characteristics indicates a positive correlation between numbers and high organic matter. Increase in density of the soil and mineral content occurs with depth and is associated with a corresponding decrease in numbers.

Other factors such as meteorological variations and non-capillary soil porosity also influence the distribution and density of Collembola. 246.

8. Up to 5 months after treatment adlicarb had less f elleeVeb,..4,res effect on mites than Collembola and other One year after treatment Collembola population had recovered more than the mites. The more rapid recovery by Collembola was attributed to reduced chemical toxicity and less competition from predatory mites. The decrease of predatory mites (Nesostigmata) populations was followed by upsurges in other groups such as Folsomia sp.,T. krausbaueri, and non-predatory mites (Astigmata, Uropodina and Prostigmata).

9. Both aldicarb andl 7inophost were less persistent in the clay than in the sandy soil. The combined effects of different faunistie compositions and insecticide persistences varied species responses and recoveries after insecticide applications to the two soil types.

Factors which might affect persistence of the toxic chemicals in the two soil types include pH, water states, adsorption on soil particles and cultivation. The micro-floraycharacteristics of the soil are also important.

10. Four bio-assay methods were used to test the susceptibility of Collembola to aldicarb and"anopho. A filter paper method testing three species of Collembola

T. krausbaueri, F. fimetaria and F. bandida using:-

(a) pure chemicals,

(b) acetone extracts of treated soil

The soil treatment method testing two species

T. krausbaueri and F. fimetaria using:- 24.7.

(a) pure chemical

(b) soil extract

T. krausbaueri was more susceptible to aldicarb than.

'Inophoe and was more susceptible to aldicarb than to its

metabolites, sulphoxide and sulphone. Juveniles of F.

fimetaria were more susceptible than adults, but their

response to soil extracts was broadly similar to that of

adults.

The bio-assays suggested that chemically-determined

concentrations of aldicarb sulphoxide and sulphone in soil

extracts were not accurate measures of the toxic metabolites

of aldicarb in the soil. When the residues of aldicarb

sulphoxide and sulphone were extracted from treated soil

and applied to clean soil they wore less toxic to

F. fimetaria than the original treated soil.

The relative toxicities of aldicarb and the sulphoxide

against Collembola spp. suggested that F. candida, was

more susceptible than F. fimetaria and both were less

tolerant than T. krausbaueri.

11. The mode of action of*inophoe and aldicarb showed an

irregular pattern of toxicity which suggest that longer

observation periods for mortality counts may be considered

worthwile for future work.

12. A comparison of 1968-69 and 1969-70 results indicates

that the repeated annual applications of aldicarb and

"Zinophos' have a continued depressing effect on populations

of soil fauna. 243.

a. Tullbcrziu,Ae showed little effects of cnrbamate and phosphorus insecticides in both soil types.

b. Onychiuridae were affected, but the effects in sandy soil were less definite with aldicarb and in clay soil treatment with'Zinophos:

c. Lepidocertidae were more adversely affected after treatment with"anophod in sandy soil, possibly because of the surface activity of insects and the fumigant action of—Enophos.

d. Responses of Isotomidae were similar to Lepidocridac except Folsomia spp appeared less affected.

e. Sminthuridae and Neelidae when separated under present investigation showed considerable difference in their susceptibility.

f. Some changes in the density of mites might have occurred during maxima and minima because of their migration.

g. Aldicarb proved more injurious to predatory mites

(Gamasina) in clay soil than in sandy soil.

h. 'Zinophosrwas less effective against mites in clay soil.

i. Non-predatory groups of Crytostigmata were completely destroyed in sandy soil.

j. Persistence of both pesticides was detectable up to 6 months after treatment by the low yields of Collembola and Acari but the response was mixed in insects of other arthropods. 13. Population increases after cultivation were observed in Isotomodes productus and Sminthuridae (in aldioarb treated plots) and Folsomia (Finophor; treated plots). 249.

14. Soil samples were taken up to 15" depth in November 1969

and to 21" in April 1970. Collembola, Acari and other

arthropod were available in deeper soil layers. The

density of T. krausbaueri and I. productus were significantly

decreased after 18" and similar indications were available

for the other arthropods.

15. The studies of culturing media showed that abundance

of mucoraceous fungus (mucor sp.) favoured the breeding

of T. krausbaueri . Folsomia sp. showed a similar response

in the presence of Penicillium sp. and Fusarium culmorum.

An examination of grit contents indicated that in the field

Collembola are not at all fastidious in their choice of

food, which included:

Fungus mycelia, decaying leaves, pollen grains,

spores, etc. 250.

1970

1. The chemical residue determination indicated that the

rate of degradation of aldicarb at Church Field in 1970 was rapid, possibly due to high rainfall during July 1970 and

the soil was uncultivated compared with previous years.

Decrease in the persistence of aldicarb in the uncultivated

soil was possibly due to its different physical adsorption

on soil particles and variations in water charecteristics

of the soil. The absence of fertiliser and increased

organic matter may have also affected persistence. Nr.*4146,40, ler 2. The densities of total Collembola and other were decreased during 6 months after treatment by 33% and 77% respectively, while the predatory and other mites

increased by 20% and 30% respectively.

3. Tullbergia krausbaueri was the most abundant species

and it was significantly diminished in treated soil sampled

fifteen days after the application of the chemical.

L. cyaneus showed a high sensitivity to aldicarb but

their number exceeded control numbers in November.

I. productus population was decreased by 81% during 6 months after treatment in the 0-9" core compared with the

control numbers.

I. thermqphila and I. viridis were reduced to zero

during the first 3 months after the chemical application but the numbers following recolonisation by I. therm*phila

surpassed the control in July.

4. The major predatory Acari, these Mesostigmata

constituted 12% of the population. An increase of 6% in the 251. faunal contribution or these predatory miters and an associated decrease of 11.4% in the faunal contribution of the Collembola during 7 months after aldicarb treatment, support their designation as predators.

Rhodocarids, Pergamasus cp., gamasid adults and nymphs were principal predators of T. krausbaueri, and also their numbers indicated a close correlation with increase or decrease of the hypogastrurids of which

Folsomia sp. were under the direct influence of those associated predators in treated and untreated areas. The population of O. trinotatus were affected by the presence of predatory mites in treated and control areas and

Pergamasus spp. were established as predators on

O. tflnotatus also.

5. Of the other Acari the Uropodina recolonised the plot rapidly after treatment and numbers equalled the control values by August in the 0-3" layer, probably as a result of a reduction of their gamasid predators.

The Cryptostigmata were very sensitive to aldicarb and population densities did not recover after the treatment until October. Prostigmata adults and nymphs in treated areas were greater than the control during

September - November. This effect may be due to an increase ak-eal ^nigo, of dead organic matters in the treated p err a stimulatory effect of the insecticide on the fecundity of the species concerned. An increase in the Astigmata was

attributed to an increase in fungal growth on soil organic-

matter. 252.

6. Enchytraeidae, earthworms, myriapods, dipterous and staphylinid larvae were decreased by aldicarb.$ince the enchytraeids are litter destroyers, soil fertility could be severely affected as a side effect of aldicarb treatment.

The population of adult insects was completely eradicated after aldicarb application.

7. Comparison of 1969 data with the 1970 data for the untreated, uncultivated plot indicated that in 1970

Collembola, Aceri and a miscellaneous fauna were decreased by 59.1%, 25.7% and 14.7% respectively, indicating a long term decrease in undisturbed soil.

8. Predators are not only exposed to the direct hazards of the chemical in the soil but also to quantities taken up in their food. It is suggested that in future chemicals should be screened for selectivity, in order to diminish dangerous side effects and endanger soil fertility and the future economic value of control operation.

9. More detailed ecological and biological information on the whole group of soil-inhabiting micro-arthropods is required. It may then be possible to interpret some of the various reactions of, and interactions between, soil organisms in relation to the persistent toxic chemicals cencitheir side-effects on the soil fauna. 253.

ACKNWLEDGEMENTS

I am Indebted to the Director of the field Station, Professor T.R.E Southwood, for the provision of research facilities; and to Dr. G. Murdie, my supervisor for his constant advice, for his invaluable suggestion and guidance. Particularly I extend my sincere thanks to him for his patient and constructive criticism of the manuscript.

Thanks are due to Mr. H.E. Goto and the late

W.O. Steel, for their help with identifications of

Collembola and other Arthropoda, respectively. Also to Mr. D. MacFarlane of the British Museum of Natural

History, and Dr. J.A. Wallwork, of Westfield College

University of London for their identification of the

Prostigmata, Mesostigmata, Astigmata and Cryptostigmata.

I should also like to thank Dr. B.E.J. Wheeler, and the

Commonwealth Mycological Institute for their identification of soil fungi. I am grateful to the late

Dr. F. Call and Dr. R.F. Skrentny, for their advice and assistance in chemical analysis.

I also wish to acknowledge Professor M.J. Way and Dr. C.T. Lewis for their encouragement, To the other members of the academic staff and to the technical staff of the College, I owe much, especially to the late

Mr. J.W. Siddorn who helped in the design and construction of extraction apparatus.

I also wish to express my gratitute for tho help and assistance received from the following; Mr. N. Khan, 254.

Miss S. McCarthy, Mrs. Sarney, Mr. R. Williams, and my colleagues at the Field Station, Ashurst Lodge, Ascot.

I am indebated to Mrs. Annemarie Baghdadi and

Miss Melitta Schmied for their patient and efficient typing of the final manuscript.

I also wish to acknowledge the Libyan Government for providing the financial support. I am especially grateful to my wife for her encouragement, inspiration

and patience, and for her help in many ways including routine calculation during the completion of the thesis. 255.

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WHEATLEY, G. A., HARTMAN, J. A., STRICICLAND, A. H. (1962) Residues of chlorinated hyaroc,nrbon lnriecticides in some farm soils in England. Plant Pathology 111 81. VITEAUP, M. (1960) Seasonal fluctuations of the fungus flora in mull and moor of an oak forest. Mede.d. Inst. toege2, Diol. Onderz Nat. (Arnhem). 46: 1-51.. WRIGHT, D. U. (1965) Aldernativee to organochlorino insecticides for the control of the carrot fly and the cabbage root fly. Ann. ap,31. Biol. 1,1 337-340.

ADDITIONAL RiLFERENCE'iS AGRELL, I. (1940). 14nt, Meddr. 22, , JOOSSE ,ELS N. G.,(1969).POpulation structure of some surfase dwelling Collembola in a coniferous Forest soil. rotherlands,l_LkSZoolopy 19 (4) : 621-34. HUGHES, R. D. (1954) The problem of sapling a grassland imoct:-31(201fittan. Ph.D. Thesis, Univ. Lond. MACFADYEN, A. (1957)a AniMal EaO16gy, AIMS end MethedS' LONDON. POOLE, T. B. (1957) Report on Forest Research for 1956: pp. 109-111. H.M.S.O. SCHALTBR, F.1949).Zur Okologie der Collemblen in Kalkstin- boden(nebst ei.nigen Bemerkungenuber Proturen). 2ool. Jb. (Syst.) 78, 263-293. O'CONNOR, F. B. (1953) Age class composition and sexual maturity in an enchytraeid wo7....m population of a coniferous forest soil. Oikos 2, 272-231.

17ILLIAM J. Bartley, NATHAN R. ANDIUMS,EDSEL L. CHANCEY, WILLIAM P. BAGLEY and HARVEY 11 . SPURR (1970)

The metabolism of Temik ALDICARD pesticide&-Moth1-2- (methylthio)propionaldehyde 0-(methycarbamoyl)oximil in the Cotton P7ant4 Agr. and Food Chemistry,18,3 p44 269.

Appendix 1. Collembola species recovered

Collembole species found to be present in- Lower Church. Field experimental_plats.

The species identified were-

Class:- IIT7ECTA

Order:- COLLE',IBOLA

Sub-order:- ARTHROPLEONA

Super-family:- Poduroidea

Family:- Hypogastruridae - Hypogastrurinae

Hypopastrura denticulata (Bagnall, 19111). Hypogastrur armata (4colet, 1841). Willemia anophthalma BOrner, 1901. - Pseudachorutinae Friesea mirabilis (Tullberg, 1871).

Family:- Onychiuridae - Onychiurinae

Onychiurus trinotatus Gisin, 1961. Onychiurus armatus (Tullberg, 1869). Onychiurus furciferus (B8rner, 1901). Onychiurus spineaus Bagnall, 19ti9. Onychiurus tricampatus Gisin, 1956. Onychiurus edinensis Bagnall, 1935. Onychiurus sp.

- Tullberginae Tullbergia krausbaueri (Burner, 1901). Tullbergia ouadrispina (Borner, 1901).

Family:- Tsotomidae

Isotomodes productun (Axelson, 1906). Folsomia cuaorioculata (Tullberg, 1871 ). Folsomi. L.m riotes (Axelson, 1903 ). Folsomia fimetaria (Linnaeus, 1758 ). Folsomia candida Willem, 1902. Folsomia litsteri Bagnall, 1939. Folsomia garret ti Bagnall, 1939. Folsomia montigena 191/. Folsomia sexoculata (Tullberg, 1871). Folsomia acheta Bacriii, 1939. Proisotoma minima (Absolon, 1900.). •TT-,5677,71.1a minor (chtlifer, 1896). Tsotomurus palustris (Nttiler, 1776 ). lsotomina therrLyhila (Axelson, 1900). Isotoma viridis Bourlet, 1839. Isotoma noLabths Sch1.ffer,186. Isotoma oliv,Acea Tullber, 1871. 270.

Super-family:- Entomobryoidea

Family:- Entomobryidae Entomobrya multifasciata (Tullberg, 1871). Pseudosinella alba (Packard, 1873). Entomobrya sp.

Family :- Lepidocyrtidae

Lepidocyrtus cyaneus Tullberg,1871. Lepidocyrtus curvicollis Bourlet, 1839. -

Family:- Tomoceridae Tomocerus minor (Lubbock, 1862). Tomocerus longicornis (Miller, 1776).

Sub-order:- SYMPITYPLEONA Family:- Neelidae

Neelus minimus (Willem; 1900).

Family:- Sminthuridae

Sminthurides (Krausbauer, 1863). Sminthurides schoetti (Axelson,- 1903). Sminthurinus elegans (Fitch, 1863). Sminthurides niger (Lubbock, 1867). Bourletiella hortensis (Fitch, 1863). •Sminthurus viridisTfannaeus, 1758). 271.

Amendix 2. Collembola -Decies recovered

Collembola species found to be present in High Field Grassland Research Instituteelkperimental plots. The species identified were:-

Class : - INSECTA Order:- COLIEMBOLA

Sub-order:- ARTHROPLEONA

Super-family:- Poduroidea

Family:- Hypogastruridae •Hypogastrurinae Huogastrura denticulate (Bagnall, 1941). Willemia anophthalma Bdrner, 1901. Hypogastrura sp.

Family:- Onychiuridae - Onychiurinae

✓Onychiurus trinotatus Gisin, 1961. Onychiurus armatus (Tullberg, 1869). Onychiurus furciferus (Bbrner, 1901 ). Onychiurus sp. - Tullberginae

v'Trullbergia krausbpueri (B6rner, 1901). Tulibergia deniSi (Bagnall, 1935').

Family:- Isotomidae

IsotemodeS productus (Axelson,.1906). Folsomia auadrioculata (Tullberg, 1871). ✓Folsomia candida Willem, 1902. Folsomia litsteri Bagnall, 1939. Proisotoma minima (Absolon, 1900). Isotomiella minor (Schaffer, 1896). Isotomurus palu:tris (Miler, 1776). v'Isotoma viridis Bourlet, 1839. Isotoma notabilis Schaffer, 1896. Isotoma, olivacea Tullberg, 1871. 272.

Super-family:- Entomobryoidea Family:- Entomobryidae Pseudosinella alba (Packard, 1873).. Orchesella sp. Entomobrya sp.

Family:- Lepidocyrtidae p--- Lepidccyrtus cyaneus Tullberg, 1871. Lepidocyrtus sp.

Family:- Tomoceridae

Tomocerus minor (Lubbock, 1862). Tomocerus lonp:icornis (Willer, 1776).

Sub-order:- SYMPHYPLEONA Family:- Neelidae

Neelus minimus (Willem, 1900). Family:- Sminthuridae Sminthurides pumilis (Krausbauer, 1863). Sminthurides sn. Sminthurinus eleff:ans (Fitch, 1863). Smintburides niger (Lubbock, 1867). Bourletiella hortensis (Fitch, 1863). SmihLhurus viridis (Linnaeus, 1758). 273.

Appendix 3. Terre'rtial Acari recovered

Acarina. species found to be -present in Lower Church Fields gxperimental plots.

The spedies identified were:-

Sub-phylum:- ARACHNIDA

Class:- ACARI Sub-class:- ACARI-ANACTINOCHAETA

Order : - MESOSTIGMATA

Sub-order:- GAMASINA

Family:- Rhodacaridae

Rhodacarus roseus Oudemans Rhodacarellus silesiac-Js Willmann Rhodacarus Ea211111 Hull Family:- Parasitidae

Eugamasus sp. Parasitus sp. Perrl.amasus teutonicus Wilimann Pergamasus crassipes (Linnaeus) Pergamasus longicornis Berlese PT:;ragamasus robustITTTOudemans)

Family:- Macrocholidae

Macrocheles sp.

Family:- Digamasellidae

Digamasellus sp.

Family:- Veigaiidae

Veigaia nemorensis (C.L.Koch)

Family:- Ascid'a2 Sub-order:- UROPODLJA

Family:- Uropodidae

Uropoda sp 271F.

Sub-class:- ACAPI - ACTINOCHAETA

-/Order:- CPYPTOSTIGMATA

Family:- Oppiidae Oppia sp.

Family:- Mycobatidae Punctoribates Dunctum (C. L. Koch)

Family:- Pantelozetidae

Pantelozetes Daolii (Ooudemans)

Family:- Ceratozetidae

Ceratozetes-gracilis ;((Michael)

4,- Order:- ASTIGMATA Family:- Acaridae

Rhizoayphus echinopus (Fumouze & Robin) Tyrophacus dimidiatus7(Hermann) GlycyphaRus sp.

Order:- PROSTIGMATA. Family:- Tydeidae

Tydeus sp. Lorryia sp.

Family:- Balaustiidae Balaustium sp. Balaustium florale (Grandj.) 275.

Family:- Scutacaridae Scutacr,rus sp. Family:- Raphignathidae Raphignathus sp.

Family:-- Eupodidae EupOdos sp,

Anystidae Anystis sp.

Family:- Ascidae

Blattisocius tarsalis (Berl.)

, Family:- PyemotidaD Pygmephorus sp. Family:- Tarsonemidae

Tarsonemoides sp. Family:- Trombidiidae

Microtrombidium sp. 276.

Appendix 4. 'Terr'estrial cari Recovered

Acarina species found to be mTesent in High Field experimental plots, Grassland Reaearch Institute.

The species identified were:- • Sub-phylum:- APACHNIDA Class:- ACM?'

Sub-class:- ACARI4ANACTINOCHAETA

Order:- MESOSTIGMATA

Sub-order:- GAMASINA

Family:- Phodacaridae

Rhodacarus roseus Oudemans Rhodacarellus silesiacus Willmann

Eviphididae

Alliphis halleri (G. &. R. Canestrini)

Family:- Parasitidae

Eugamasus sp. Pergamaus craasipes (Linnaeus) Pergamasus mirabilis ':Iillmann Paragamasus suecicus (Tragardh) Permamastu sp.

Family:- Digamasellidae

Digamase]-lus sp. Family:- Gamasolaelapidae

Gamasolaelaps sp. Family:- Ascidae

fIrctoseius cetratus (ell n) Gamasellodes sp. Sub-order:- UROPODINA

Uropodidae Uropodid deutonymph 277.

Sub-class:- AC/dRI- ACTINOCHAETA

Order : - CRYPTOSTIGMTA Family:- Oppiidae

Oppia sp. Oppia subpectinata Oudemans)

Family:- Nothiidae

Nothrus sp.

Family:- Camisiidae

Pl:.-tynothrus -peltifer (C. L. Koch) Family:- Phthitacaridae

Phthiracnrus sp. Family:- Mycobatidae

Minunthozetcs semirufus (C. L. Koch. ) Order:- ASTIGMATA

Family:- Acaridae Rhizorayphus echinopus(Fumouze & Robin) Tvropharus putrer-centiae (Schrar4) CaloglyDhus berlese (Michael)

Order:- PIOSTIGMATA Family:- Alicorhagiidae

Alicorhagia sp. Family:- Trombidiidae

Allothrombium fulp;inosum (Herm.) 278.

The methods of sampling and extraction used were not adequate for soil fauna other than the collembola and some Acari species. .A two specimens of the following species of earthworms and enchytraeids were recovered.

Appendix 5. Invertebrates recovered

Other groups of animals extracted in Lower Church Field and Experimental plot of High Field.

Class:- OLIGOCUIETA

Family:- Lumbricidae

AllolOophora caliginosa Allolobophora chlorotica Allolobophora rosea Immature Lumbricus species

Family:- Enchytraeidae

Achaeta bohemica. Henlea perpusilla Henlea SP. 279

Appendix 5A. Analysis of Experiments.

Church Field,_Silwood Park and Hig.h Field, Hurley, 1959.

The three treatments(untreated 'control', 'Zinophos' and

aldicarb) were laid down in two randomised blocks -at each site.

At Church Field five random/Cores were taken monthly (June to * November) from each plot while at High Field only four 747" cores

were taken per plot from July to-November. The fauna extracted

were classified and grouped into species, genus, etc, for each

3" layer, ie. 0 - 3",.3 - 6", 9", and 9 - 12" for Church

Field, 0 - 3" and 3 6" for High Field (final 12" not analysed;,

The counts were transformed to log10 (n 4. 1) and the sites

and sampling depths analysed separately by analysis of variance:-

Church Feild High Field

Source of Variation; Degrees of Freedom:. Degrees of Freedom

Chemicals 2,

Blocks i 1

Chemicals x Blocks 2 • 2

Dates 5 4,

Chemicals x Dates 1 0

Flocks x Dates 5

Chemicals x Blocks x Dates 10 ,8 144 90 Total 179 119

The mean square for the triple interaction term was

considered the most appropriate measure of interplot variation

and was used to test main effects and binary interactions and

for the comparisons of treatment means, Comparisons were made 280 between treatment means for each date of sampling by using the least significant difference (LSD);- 2 • LSD T. t 2s i n t is student's 't' chosen at either 5% or 1% probability and degrees of freedom of the interaction term (10 for Church Field and 8 for High Field). s2 is the triple interaction mean square and n the number of samples on which each is based (5 for Church

Field and 4 for High Field).

Tests of mean differences were only, done for the major spedies and groups, namely: T.. krausbaueri; Isotoma;sPP;

Onychiurus spp; Folsomia spp; Lepidocyrtus spp; Prostigmata;

Mesostigmata; Cryptostigmata; and Astigmata.

The significance of difference between pairs of means for each sampling date are shown on the appropriate figures as Z 5 and A for example, indicating differences significant at 5% 1, and 1% between the marked mean and the 'Zinophon' and aldicarb mean respectively.

Appendix: 5B

Church Field 1970

The experiment was set out as a single plot with the

un7reated, central area surr-.unding the central aldicarb-

treated area. Random 9" cores (8 untreated and 12 treated) were taken on eleven sampling occasions from May to November.

Double samples in June, July, August and October were pooled

to give the monthly means which were therefore based on. 16 and

24 core samples for untreated and treated areas respectively.

As in 1969 the fauna extracted were pooled into 3" layer

extractiohs (0 - 3", 3 - 6", and (; - 9") transformed to log10 (n.;.. 1) and each depth was analysed separately. The

differences between means for each date were tested using least 281 significant difference (LSD) at 5%, 1% and 0.1% levels of probability. Where significant differences were found the appropriate sample means have been marked by .05 (5%), .01

(1%), or .001 (.1%). on the relevant figures.

The form of the analysis of varience is:-

Source of Variation Degrees of Freedom

Treatment 1

Dates 10

Treatments x Dates 10

Residual 198

Total 219

The LSD values were calculated from:-

2 2 i s + S ni n 2

2 is the residual mean square and n and n the monthly where s ' 1 2 sample sizes for the untreated and treated means respectively. 282. Appendix Table 6. Table 1

The fate of aldic..arb (Temik 10 G) granules broadcast on the surface of Church Field and High Field soil in May of 1969. 1Results in ppm)

CHURM FIELt ' Time in Months 1 2 3 4 6 12 0-6 inch layer

Sulphoxide 3.0 1 0.4 0.25 0.10 0.02 a Sulphone Trace 0.1 0.25 0.40 0.15 Trace

Total 3.0 1.1 0.65 0.65 0.25 0.02

6-12 inch layer

Sulphoxide 0.3 0.5 0.5 0.5 0.3 0.01

Sulphone NDb ND 0.2 0.35 0.2 Trace

Total 0.3 0.5 0.7 0.85 0.5 0.01 total 3:3 • 1.6 1%35 -I-45a- 0.75 - 0,o3e - HIGH FIELD

0-6 inch layer

Sulphoxide 2.5 1.2 0.1 0.04 '0.02 0.01 .

Sulphone ND ND ND ND • 0.01 ND

Total 2.5 1.2 0.1 0.04 0.03 0.01 6-12 inch layer

Sulphoxide 0.6 • 0.2 0.05 0.02 0.01 Trace

Sulphone ND ND ND ND 0.01 ND d Total 0.6 0.2 0.05 0.02 0.02

0-12 inch total 3.1 1.4 0.15 0.06 0.05 0.01

a - Trace = less than 0.01 ppm b - ND = Not detected c - Analysis of Church Field soil at 12-18 inch depth after one year indicated a trace of sulphoxide but no sulphone. d - Analysis of High Field soil at 12-18 inch depth after one year indicated no sulphoxide or sulphone detected.

R. Skrentny (1970) Ph.D thesis University of London. 283.

Appnndix Table 7. Ticantem73erature and rain--fall total durin/,- field studies*

T2,11:727aL7 TURF, RAIN-FL LI, TOTAL TEAR MONTH (°C . j Ii x:11

-■• 1968 April 7.3 57.9 May 10.2 77.9 June 15.0 81.6 July 15.3 72.2 August 15.1 65.1 September 13.6 137.4 October 12.7 73.4 November 6.3 52.9 December 2.5 89.0

1969 January 5.0 84.6 February 5.3 50.9 March 4.1 59.0 April 7.8 6.3 May 11.4 70.5 June 13.4 31.1 July 17.4 56.o August 16.0 37.6 September 14.2 8.6 October 12.3 6.6 November 3.8 80.o December 3.4

/contd. 284.

A rs2c 7 . i oontd

YEAR MONTH TERATURE RAIN-FALL TOTAL haeir (°C.) MEAN

1970 January 2.7 33.7 February 3.1 5o.4 March 3.4 37.2 April 6.0 61.0 May 13.0 24.8 June 16.2 72.0 July 16./ 43.4 August 15.2 49.6 September 14.1 54.0 October 10.4 10.5

November • ■■•• 16.9 December

* Silwood ?ark Ma'in Meteorological Sftes Latitude 51° 28' N. Height Above M.S.L. 220' 285. Lppendix 8.

The plant s2ecico f:uod in the plots of Lower

CI-urch Fiele" Silwond arh Species

Ga7ZAITZACDA2 atiai0=ELLACLLE Snerzula arvensis

Ste llaria media

CEL:NOYODIAC72,A21). Chononodjup alum

SOLIITACEAE Solanum nifxrum

?A?ILIONACEAE Trifolium renens

COMPOSITAE Senecio

Cronis canillaris

GPAPIII%A.0 Poa apnua. Holcuo mollis

11 Agromrron reoens

CRUCIF3RA2,- Capsella bursa-nastoris

Sina'iis arvensjs

P0LYGONACEA2- Polygonum convolvulus

11 2olyg.onum pea;•picarja

11 Polygonum ayicularp 286.

Appendix 9.

Tao plant s7leni.c40 C:xund :in the -plots of 17,1g11

Field, ::urley,

eel

CllATITITID.A31' ?1- -,_2_,eun, ra_:bense

•11 Holcus sz)?.

LEGI=CSA2 Trifo:!,ium rpoens.

IT Tr±foliu D:2PtePse SOIANACME Solanum tuberosum

COM?CSITAS Poncb:P.P. 1..,scpsana. p.o.mpurvis

Tri-31envosnermum par,itiranl

Taraxacum officinale

POLYGONACAID Rumex pb:L;upifolius

Pol-w-aonum aviculare

PLAITT4GTITAC2AID Plantago major_

OROBAHOT_IClUE Orobanclle minor

UMBELLIF3RAE arvensis

PAPUZRACZAE 2Apaver rhpeas

RAITUITCULACIIIAE RaPuncll. repe,Ps

PRIMULAUA2, pryensis

E=OR3IAC2AE ;Tp-c.liorbia exigua. 287.

Appendix 10.

Application of aldicarb in the field (1970)