Abdulgader A. Sherif, B.Sc. (Cairo), D.I.C
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1. 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 pest- icide 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 organo- phosphorus 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 import- ant 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