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University Microfilms International 300 N. ZEEB ROAD, ANN ARBOR, Ml 48106 18 BEDFORD ROW, LONDON WC1R 4EJ, ENGLAND 8008754

ABREU, J0A0 MANUEL DE

SURVEY, MONITORING AND CHEMICAL CONTROL OF IN STORED CACAO, BAHIA, BRAZIL

The Ohio State University PH.D. 1979

University Microfilms International300 N. Zeeb Road, Ann Arbor, MI 48106 18 Bedford Row, London WC1R 4EJ, England SURVEY, MONITORING AND CHEMICAL CONTROL OF INSECT

INFESTATIONS IN STORED CACAO, BAHIA, BRAZIL

DISSERTATION

Presented in Partial Fulfillment of the Requirements for

the Degree Doctor of Philosophy in the Graduate

School of the Ohio State University

By

Joao Manuel de Abreu, M.Sc.

A A A A A . t . . r . A A A A A

The Ohio State University

1979

Reading Committee: Approved by

Dr. Roger N. Williams Dr. David J . Horn Dr. William J. Collins (j Adviser Department of Entomology Dr. Glen R. Needham my wife ,

Children, and

Parents ACKNOWLEDGMENTS

Acknowledgments are made to the Comissao Executiva do

Plano da Lavoura Cacaueira (CEPLAC), and Empresa

Brasileira de Pesquisa Agropecuaria (EMBRAPA) for the financial support provided for my higher education, and to the American Cocoa Research Institute (ACRI) which partially financed this research.

My deepest gratitude to Dr. Roger N. Williams for his guidance, understanding, encouragement and friendship.

Many thanks are due to the members of my Committee,

Dr. David J. Horn, Dr. Donald E. Johnston, Dr. William J.

Collins, and Dr. Glen R. Needham.

I appreciate the help of Jose Pacheco de Brito Filho,

Selene Cristina Badaro, Marizete Pereira dos Santos, Rui

Dorea Magalhaes Filho and Vivaldo Marques da Cruz Filho, in the field and in the laboratory.

Dr. Forbes Peter Benton gave invaluable help in correcting the manuscript.

Mr. Nelson Campos Moreira drew the figures.

* Thanks are due to Miss Ana Amelia Lins Guimaraes for typing the manuscript. VITA

January 27, 19 3 9 Born, Viseu, Portugal

1963 ...... Eng. Agronomo, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil

1964-1969 ...... Research Assistant, Division of Entomology, CEPLAC, Itabuna, Bahia, Brazil

1971...... M.Sc., Universidade de Sao Paulo, Piracicaba, Sao Paulo, Brazil

1971-1976 ...... Research Associate, Division of Entomology, CEPLAC, Itabuna, Bahia, Brazil TABLE OF CONTENTS Page

DEDICATION...... ii

ACKNOWLEDGEMENTS...... iii

VITA...... iv

LIST OF TABLES...... viii

LIST OF FIGURES...... xi

INTRODUCTION...... 1

REVIEW OF LITERATURE...... 3

MATERIALS AND METHODS...... 15

I. Survey of AttackingStored-Cacao.. 15

Experiment 1 - Survey by means of sieving. 15 Experiment 2 - Monitoring for insect pests in a cacao warehouse using food traps...... 16

II. Evaluation of Insect Trapsin Warehouses.. 19

Experiment 3 - Comparison of fluorescent lamps with different wave­ lengths operated simul­ taneously...... 2 0 Experiment 4 - Comparison of fluorescent lamps with different wave­ lengths operated indepen­ dently...... 2 3 Experiment 5 - Influence of lamp wattage on the catches of insects associated with stored- cacao...... 2 3 Experiment 6 - Fluorescent lamps and sex influence on suction trap catches of E. cautella...... 24

v Page

Experiment 7 - Effect of the sex phero- mone release rates on E. cautella catches 2 6 Experiment 8 - Effect of height on the sex pheromone trap catches of E. cautella...... 27

III. Chemical Control...... 2 8 Experiment 9 - Evaluation of insecticide sprays for the protection of bagged cacao...... 2 8 Experiment 10 - Evaluation of fumigation on insect pests in bagged cacao using phosphine...... 3 0

RESULTS AND DISCUSSION...... 3 3

Experiment 1 - Survey by means of sieving... 3 3 Experiment 2 - Monitoring for insect pests in a cacao warehouse using food traps...... 51 Experiment 3 - Comparison of fluorescent lamps with different wave­ lengths operated simul­ taneously...... 5 9 Experiment 4 - Comparison of fluorescent lamps with different wave­ lengths operated indepen­ dently...... 6 8 Experiment 5 - Influence of lamp wattage on the catches of insects associated with stored-cacao. 7 0 Experiment 6 - Fluorescent lamps and sex pheromone influence on suction trap catches of E. cautella...... 73 Experiment 7 - Effect of the sex pheromone release rates on E. cautella catches...... 77 Experiment 8 - Effect of height on the sex pheromone trap catches...... 8 3 Experiment 9 - Evaluation of insecticide sprays for the protection of bagged cacao...... 85 Experiment 10 - Evaluation of fumigation on insect pests in bagged cacao using phosphine...... 92

vi Page

GENERAL DISCUSSION 9 9

CONCLUSIONS...... 102

SUMMARY...... 10 8

BIBLIOGRAPHY...... Ill

vii LIST OF TABLES

Table Page

1. Number of cacao bags sieved at the port of Ilheus before fumigation and shipment...... 3 8

2. Total numbers of insects collected from sievings ofcacao bags...... 3 9

3. Average number of insects per cacao bag from all the bags sampled at the port of Ilheus...... 4-0

4. Mean weight (g) of debris plus frag­ mented cacao beans obtained by sieving cacao bags...... 41

5. Total insects caught in food traps in a cacao warehouse in Ilheus, from March, 1978 to March, 1979 ...... 54

6. Mean numbers of insects caught in light traps operated simultaneously 4.5 0 m high in cacao warehouse A. Ilheus, Bahia, April, 1978...... 62

7. Mean numbers of injects caught in light traps operated simultaneously 1.0 0 m high in cacao warehouse A. Ilheus, Bahia, April-May, 1978 ...... 63

8. Mean numbers of insects caught in light traps operated simultaneously 4.00 m high in cacao warehouse B. Ilheus, Bahia, May, 19 7 8 ...... 6 4

9. Mean numbers of E . cautella caught in light traps operated simultaneously 4.5 0 m high in cacao warehouse C. Ilheus, Bahia, August-September, 197 8 ...... 6 5

viii Mean numbers of insects caught in light traps operated independently in the Gerais cacao warehouse. Ilheus, Bahia, September-December, 19 7 8 ...... 69

Insects captured in light traps as influenced by the lamp wattage. Ilheus, Bahia, November-December, 1978;...... 71

Mean numbers of E. cautella caught per • trap in a cacao warehouse. Ilheus, Bahia, December, 19 7 8 ...... 75

Mean numbers of L. serricorne caught per trap in a cacao warehouse. Ilheus, Bahia, December, 19 7 8 ...... 76

Mean numbers of the anthocorid bug, X . afer caught per trap in a cacao warehouse. Ilheus, Bahia, December, 197 8 ...... 76

Mean numbers of E. cautella captured per trap in a cacao warehouse. Ilheus, Bahia, September-October, 197 8 ...... 79

Mean numbers of E. cautella captured in traps baited with the pure sex pheromone. Ilheus, Bahia, October, 19 7 8 ...... 80

Mean numbers of E. cautella caught on sex pheromone baited traps at different heights in a cacao warehouse. Ilheus, Bahia, October, 1978 ...... 84

Means of transformed insect counts fol­ lowing application of insecticides to cacao bags. Ilheus, Bahia, February, 197 8, December, 19 7 8 ...... 88

Means of transformed L. serricorne and T. castaneum counts following application of insecticides to cacao bags. Ilheus, Bahia, February, 1978 - December, 1978 ...... 89

Number of insects collected in the four untreated bags sampled at different periods of storage. Ilheus, Bahia, February - December, 19 7 8 ...... 90 ix Table Page

21. Means of transformed counts following fumigation of cacao bags using phosphine. Ilheus, Bahia, March, 1979...... 94

22. Means of transformed insect counts after fumigation of cacao bags using phosphine. Ilheus,Bahia, March, 1979.... 95

23. Effect of fumigation of cacao bags using phosphine against Coleoptera. Ilheus, Bahia, March, 1979 ...... 96

x LIST OF FIGURES

Figure Page

1. Cacao region of Bahia...... 17

2. Position of light traps in warehouse...... 22

3. Percentage of cacao bags not infested coming into the port of Ilheus from the Northern Zone of the cacao region...... 42

4. Percentage of cacao bags not infested coming into the port of Ilheus from the Central Zone of the cacao region...... 43

5. Percentage of cacao bags not infested coming into the port of Ilheus from the Southern Zone of the cacao region...... 44

6. Mean number of E. cautella larvae infesting cacao bags...... 45

7. Mean number of T. castaneum infesting cacao bags ...... 46

8. Mean number of A. advena infesting cacao bags...... 47

9. Mean number of C. dimidiatus infesting cacao bags...... 48

10. Seasonal abundance of stored-cacao insects in a warehouse in Ilheus, Bahia.... 55

11. Seasonal abundance of E. cautella in a cacao warehouse. Ilheus, Bahia...... 5 6

12. Seasonal abundance of in a cacao warehouse. Ilheus, Bahia...... 5 6

xi Figure Page

13. Seasonal abundance of T. castaneum in a cacao warehouse. Ilheus, Bahia 57

14-. Seasonal abundance of C. dimidiatus in a cacao warehouse. Ilheus, Bahia...... 57

15. Seasonal abundance of A. advena in a cacao warehouse. Ilheus, Bahia...... 5 8

16. Seasonal abundance of L. serricorne in a cacao warehouse. Ilheus, Bahia ..... 5 8 INTRODUCTION

The exportation of bagged dry cacao beans from Bahia,

Brazil involves three stages of storage starting at the grower's estates, then later at the local marketing centers and finally at the port of Ilheus prior to shipment. The time it remains in storage at any one of these places can vary from a few days to months depending on the prevailing circumstances.

Insect problems arise in infested ware­ houses especially if cacao is stored longer than 3 0 days between harvest and shipment. Apart from causing direct losses, insect infestation also leads to the risk of con­ tamination from feces, odors, webbing and fragments being incorporated into the final chocolate products. Financial losses are also caused by downgrading cacao consignments if tolerable levels of insect infested beans are exceeded.

Other losses include the cost of fumigation and expenses of applying them. In addition, it is quite an expensive task to remove insect fragments that become mixed with the cacao beans prior to chocolate manufacture.

The present investigation was carried out to determine the major storage-pests and the degree to which they infest cacao. Methods used to detect or monitor stored populations were investigated and an evaluation was made of insecticides for the protection of bagged cacao from insect attack. REVIEW OF LITERATURE

Studies on insect pests of stored-cacao are limited in Brazil. The occurrence of the corn ,

Carpophilus dimidiatus F. was reported by Bondar (1938) causing serious damage to cacao. Silva (1947) attempted to control the almond moth, Ephestia cautella (Walker) with a very promising parasite of its identified as Bracon hebetor Say, which was found in the cacao stores. Later,

Pigatti (I960) conducted a test to control E. cautella using methoxychlor applied directly to the cacao beans and to the outside of the bags. This insecticide gave complete control when applied to the beans at 1:1000 by weight and with only moderate success when applied to the outside of bags. Residues on the beans were 4 0 and 1 ppm, respect­ ively. 'Ghosh and Silva (1972) and Silva (1974) reported E. cautella, Lasioderma serricorne (F.), Araecerus fasciculatus

(De Geer) and Spermologus rufus (Boh.) as the most important pests of stored cacao in the State of Bahia. However, there were no estimates as to the degree of infestation. Silva and Bastos (1974) reported 18 of insects associated with cacao in storage. Recently, Silva (1977) recorded

Oryzaephylus surinamensis (L.), 0. mercator (F.), Gibbium 4

psylloides (Czenpinski) and Attagenus megatona (Fab.)

associated with stored-cacao beans in warehouses at Salva­

dor and Ilheus, Bahia.

References to insect pests of stored-cacao are more

frequently found in other producing and importing countries.

Munro and Thomson (192 9) carried out a survey of insects

in the London warehouses and found that Ephestia elutella

(Hub.), A. fasciculatus and Corcyra cephalonica Staint, were the chief insects infesting cacao, the first being the Y most important. In the next year Noyes (193 0) reported that the chief pest of cacao beans and chocolate are E. elutella,

Ephestia kuniella Zeller, E. cautella and Plodia inter- punctella (Hub.) and explained that cacao beans are infested before arrival at the factory in England. In addition,

Nicol (1938) carried out investigations into the sources of infestation of cacao beans. This survey showed that E. cautella and E. elutella are the chief pests. He found that

E. cautella predominated in cacao from West Africa, Trini­ dad, Grenada and Ceylon, whereas the majority of moths from

Brazil and Venezuela were shown to be the tobacco moth, E. elutella.

In Ghana Cotterell (19 34) reported infestations of cacao in stores by A. fasciculatus and E. cautella. He also described damage to beans, life histories, sources of in­ festations, prevention of infestation and control in infested stores. Beside E. cautella and A. fasciculatus, Forsyth

(1957) also included L. serricorne among the species occurring in severe infestations in warehouses at Takoradi,

Ghana. A survey was also carried out by Cranhan (1960) to assess insect -infestation of stored raw cacao in Ghana.

The results showed that E. cautella was the most abundant and economically important, followed by L. serricorne, A. fasciculatus, T. castaneum, C. dimidiatus, Cryptolestes spp. and Ahasverus advena. He also reported Cryptophagus sp. and Gnathocerus maxillosus straying into cacao in small numbers. Other species found in cacao coming into storage include Sitophilus oryzae, Oryzaephilus surinamensis,

Palorus subdepressus, Necrobia rufipes and Tenebroides mauritanicus. Psocids, , predaceous anthocorids, a silvanid, hymenopterous parasites and unidentified spiders were reported to occur in the cacao warehouses.

Recently, Kisiedu and Ntifo (197 5) stated that insect infestations were the main problem during cacao storage in

Ghana. The insects usually found included E. cautella, L. serricorne, A. fasciculatus, T. castaneum and sp.

Cotterell (1952) reported that E. cautella and L. serricorne are the major pests of stored cacao in Nigeria.

Infestations originate in the farms and broker's storage premises, which are generally small, rarely cleaned and may contain small parcels of beans which are below standard.

Riley (1957) investigated the rate of build up of infes­ tation in bagged cacao beans in store in western Nigeria.

The work carried out on a two ton stack of cacao in 3 2 bags, showed that E. cautella and L. serricorne were the major pests followed by T. castaneum. He also estimated that on the average it is not safe to store initially good cacao for more than 2 5 weeks in the main crop season. In another paper Riley (1969b) showed that C. pusillus and A. advena were the most numerous in the sievings from whole bags followed by 0. mercator and T. mauritanicus.

The species most frequently found in Sao Tome were the following according to Gouveia and Souza (1968): 0. mercator, A. advena, L. serricorne, C. dimidiatus and

Necrobia rufipes■

In Trinidad and Jamaica, E. cautella, L. serricorne,

T. castaneum, 0. mercator and A. advena can be considered the most common insects in stored cacao based on the work on the protection of stored cacao beans carried out by

Brooke et al. (1962). These authors reported a parasitic

Hymenoptera attacking P. interpunctella. The presence of mold-feeding insects, Typhaea stercorea and Carpophilus sp., was also reported.

Howe and Freeman (195 5) published the results of in­ spections for infestation by insects of west African produce imported into Britain. E. cautella, T. castaneum, L.

serricorne, N. rufipes , A. fasciculatus, A. advena, T.

mauritanicus, Carpophilus sp. and Cryptolestes sp. were

in more than ten per cent of cargoes of cacao beans.

Other importing countries of Europe have also carried

out surveys on the cacao arriving from exporting countries.

The occurrence of E. cautella and E. elutella were reported

by Schulten (1965) in Netherlands, by Somme (1959) in Nor­

way and by Knoche (196 3) and Strumpel (1969) in Germany.

According to Lavabre (1965), E. cautella, L. serricorne

A. fasciculatus, C. dimiatus, A. advena, Gnathocerus max-

illosus, T. castaneum and T. confusum are the most frequent

insects found attacking cacao in storage. However, Entwist-

le (1972) lists E. cautella, E. elutalla, A. fasciculatus, id* serricorne, T. castaneum and Trogoderma granarium as the most important insects associated with stored-cacao.

Some studies were carried out to determine attractive­ ness of stored-products insects to electromagnetic radia­

tion in the hope of luring these insects to a trap. Stermer

(1959) conducted laboratory studies to determine the

spectral response of seven species of stored-products

insects. Nine narrow wavebands of radiation between 2 8 0.4 and 600.0 nm were used for the tests. E.. cautella and T.

castaneum preferred a wave band which peaked near 50 0 nm in

the green prrtion of the spectrum. The results of this study indicate that a low-wattage lamp having a relatively

large output from 47 5 to 52 5 nm would be most efficient

in grain warehouses. Also, Kirkpatrick et al. (1970)

conducted tests to determine whether a combination of green

and UV light would be more effective than either alone in

attracting stored-product insects to traps. According to

the results none of the insects showed a significant preference for the combination of green plus UV light over the UV alone. E. cautella and P. interpunctella preferred the independently operating green light, whereas L.

serricorne, Cryptolestes pusillus (Schoenhen) and

Rhyzopertha dominica (F.) were significantly less attracted to green light when operated one at a time. Soderstrom

(197 0a) carried out tests to compare green electrolumines­ cent lamps with a circline UV lamp for their attractiveness to stored-product insects. The lamps were mounted in suction traps placed in laboratory rooms and in ware­ houses. E. cautella showed no preference for the two kinds of light tested, whereas L. serricorne, 0. mercator and T. castaneum responded in greater numbers to UV lamp radiation.

Again, Soderstrom (19 7 0b), studying the phototactic response of stored-product insects to various intensities of

UV light found that high intensities were most attractive to T. castaneum, 0. mercator and C. pusillus, whereas L. serricorne responded in higher numbers to lower intensities. Hagstrum et al. (1977), studying the flight activity of E. cautella as influenced by intensity of UV or green radiation, found that suction traps fitted with lamps captured higher numbers of the almond moth. They suggested that the lamps themselves were not a direct source of attraction to the moths but that they increased the level of ambient radiation in the experimental room which in turn increased the flight activity of the moths.

The use of sex for controlling stored- product insects have been attempted in recent years..

Kuwahara et al. (1971) and Brady et al. (1971) simultaneous­ ly reported the identification of the sex pheromone (Z)-9,

(E)-12-tetradecadienyl acetate isolated from females of E. cautella and P. interpunctella. Later, other components of the sex pheromone complex of E. cautella and P. inter­ punctella were reported by Brady (1973), Vick and Sower

(1973), Sower et al. (1974), and by Read and Beevor (1976).

Recently, Read and Haines (197 6) conducted field experi­ ments in a small maize store and in a large wheat store to evaluate the attractiveness of males to three synthetic compounds (and various combinations of them) from the sex pheromone complex of E. cautella. It was shown that (Z)-9,

(E)-12-tetradecadienyl acetate is the major attractant to the males in the complex. (Z)-9-tetradecenyl acetate, although not attractive to males on its own, is a synergist 10 to the major attractant and (Z)-9, (E)-12-tetradecadienol is not attractive to males alone but was shown to inhibit the attractiveness of the major attractant.

In Germany, Reichmuth et al. (197 6) demonstrated the value of (Z)-9, (E)-12-tetradecadienyl acetate vaporized from plastic capsules for the early detection of P. interpunctella and E. elutella in large warehouses and in a chocolate factory. In addition, Haines (197 6) reported a trial in cacao stores in Nigeria with two concentrations of (Z)-9, (E)-12-tetradecadienol to assess the effect of this compound on population growth of E. cautella.

Several studies were undertaken with the aim of con­ trolling insects of stored-cacao with pyrethrum plus piperonyl butoxide and dichlorvos. In Ghana, Cranhan

(1960) compared infestations in sprayed and unsprayed sheds after application of synergized pyrethrins in white oil as a fog from which a film was deposited on the stacked bags of cacao. He found that treatment did not control L . serricorne or other beetles, nor was E. cautella controlled to a degree compared with similar reports in Britain.

Brooke et al. (1962) have shown that emulsion sprays con­ taining pyrethrins and pyperonyl butoxide applied to cacao beans gave some protection against T. castaneum and E. cautella in Trinidad, but had no effect against E. cautella or L. serricorne in Jamaica. In Ghana, Mould and Rawnsley 11

(1962) reported the results of two experiments to control the cacao moth. In the first experiment, space sprays of pyrethrins in oil, alone or mixed with ten times the amount of piperonyl butoxide were highly effective against E. cautella. The most satisfactory concentrations of pyre­ thrins appeared to be between 0.05 and 0.2 per cent. In the second experiment, the same materials were tested as thermal aerosols causing increasing mortality with the concentrations of pyrethrins up to 0.4 per cent, at which i almost 100 per cent mortality was obtained. The synergist again had no effect. Later, Rawnsley and Mould (196 5) showed that films of pyrethrins plus piperonyl butoxide were ineffective against the almond moth because they lasted but a few hours. Successful control was obtained by application each evening of a dry fog derived from 0.5% of pyrethrins in odorless white oil, produced by portable thermal fog generators. No synergistic effect was found when piperonyl butoxide was included in the formulation.

This technique is relatively ineffective against the larvae.

Rawnsley (196 8) achieved complete or nearly complete con­ trol against the almond moth after about 6 0 days by in­ jecting a pyrethrin fog into each warehouse at dusk to kill the adults before they could mate.

In Nigeria, Smith (195 2) conducted experiments to determine whether DDT sprayed at the outside of cacao bags would give protection against E. cautella and T. castaneum.

Fumigated cacao bags were sprayed with a 5% suspension of

DDT wettable powder in water at a rate of 95 6 mg per sq ft 2 (ca. 10 g/m ). The insecticide had no effect in preventxng infestation by E. cautella but it was effective in prevent­ ing T. castaneum from entering into the cacao bags. Cornes

(1966) showed that DDVP impregnated strips, hung in a warehouse containing about 400 tons of bagged cacao beans, caused little or no reduction in the numbers of E. cautella.

Later Riley (1969a) reported that although DDVP plastic strips eliminated almost all adults of E. cautella from the air space around the stacks and may have prevented multi­ plication of L. serricorne, which occurred only in untreated cacao, it was concluded that the strips are not sufficiently effective for general use in cacao warehouses because they had no effect on other beetles.

Kisiedu (1971) showed that dichlorvos was more effec­ tive than pyrethrins in controlling E. cautella, L. serri­ corne , T. castaneum and Sitophilus oryzae (L.) . These insects were exposed in empty cacao sheds to fogs of pyre­ thrins or dichlorvos at 0.0 2% - 0.8% applied at rate of 1 3 liter/142 m . It was concluded that if dichlorvos did not taint the crop or result in unacceptable residues it would be more economical than pyrethrum for daily treatment. Experiments were also undertaken using fumigants to control insect pests of stored-cacao. A preliminary evaluation of phosphine as a fumigant for cacao beans was carried out by Cornes and Halliday (1966) using two stacks of 5 bags covered with plastic sheets. One stack was fumi­ gated at a dosage rate of 4 tablets/5 bags for 7 2 hr, and the other was the control. The assessment of infestation showed only one living insect in the fumigated bags, and

10 5 in the unfumigated bags. Riley and Simmons (19 6 8a) conducted tests in a cacao warehouse especially designed for fumigation, using phosphine against T. castaneum, L. serricorne, C. pusillus, 0. mercator, A. advena, C. dimidiatus, Thaneroclerus buqueti, T. mauritanicus, X. afer, Holepyris hawaiiensis and E. cautella. Phosphine tablets were applied at the rate of 3.34 per ton of cacao at the top and bottom of the stacks and no plastic sheet was used. Survival and reinfestation were measured by suction trap catches and by seiving the contents of 2 0 sample bags removed at intervals after fumigation. In­ festation was reduced by 9 9% one week after treatment and by 9 6.8% five weeks later. Again, Riley and Simmons

(1968b) using the same facilities and methods of sampling the insect population carried out experiments using methyl

■bromide. Greater than 9 8% reduction in infestation was achieved between one day and five weeks after fumigation. Kisiedu and Ntifo (1975) reported that during the peak of the cacao season stores are frequently fogged with pyrethrum especially to control the almond moth. At the ports, every cacao consignment is fumigated with methyl bromide prior to exportation. At the end of each season residual infestations are eliminated by cleaning and spray­ ing the stores with bromophos. MATERIALS AND METHODS

I. Survey of Insects Attacking Stored-Cacao

The survey was conducted in two warehouses located on ■

the pier of the port of Ilheus and in a single warehouse

located in Ilheus in the State of Bahia, Brazil. Deter­

mination of insect pests of stored-cacao was accomplished

by sampling sacks of stored-cacao beans and using food

traps in a cacao warehouse.

Experiment 1 - Survey by Means of Sieving

Assessment - of insect infestations by means of sieving

was initiated in May, 1978 and continued until March, 1979,

to cover the cacao crop season. Six bags were taken from

each sampled truck arriving at the port of Ilheus and these

bags were sieved to separate the insects from the cacao

beans. Only sealed, superior graded cacao of export quality was utilized. It was sieved before fumigation and shipment.

A 7 0x12 0 cm sloping sieve of 5 mm mesh standing on four legs

and having a pyramidal plywood funnel beneath was used.

This is a modification of the sieve used by Cranhan (1960)

in Ghana. Each cacao bag was emptied at the top of the

sieve and moved slowly by hand down the sieve so that insects 16

together with cacao fragments and debris fell through the

funnel into a 40x-50 cm fabric bag, whereas the cacao beans

passed through a short duct and fell into the jute bag

(60 kg). An average of 244 cacao bags were sieved per month.

The sievings were weighed and placed in Berlese funnels for

8 hours, to extract-live insects and mites from each sample.

Insects (larvae and adults) falling into the vial were

sorted, identified and counted with the aid of stereomicro-

scopes having 10 to 4-0 X magnification^. In addition, the rest of the sievings were removed from the Berlese funnels

and placed in 36 x 50 x 2 cm aluminum trays for hand re­ moval of any remaining live or dead individuals.

An analysis was carried out in order to calculate the

sample mean and the standard error for the monthly samples,

for the sample obtained from three cacao producing zones of the cacao region of Bhaia (Fig. 1), and for the total

samples of each major insect or group of insect pests.

Experiment 2 - Monitoring for Insect Pests in a Cacao

Warehouse using Food Traps

The incidence of stored-cacao insects and their

seasonal abundance was also determined by means of food traps. The traps consisted of aluminum trays measuring 2 0

This type of stereomicroscope was used in all the experiments. Figure 1. Cacao Region of Bahia

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CACAO REGION OF BAHIA

PORTO SEGURO ONE CENTIMETER EQUALS APROX. EIGHT KILOMETERS 10km 10 4 0 km

CITIES CACAO PLANTATIO NS ROADS

ITAMARAJU

BAHIA

18° 00 I8°00 4 0 ° 3 0 3 9 ° 00 19 x 30 x 2.5 cm filled with the following rearing medium per trap: wheat flour (100 g); cornmeal (100 g); and Brewer’s yeast (5 g). 2 One room with 770 m of floor space m an warehouse was sampled at Ilheus. Six traps were distributed as evenly as possible at an approximate rate of one trap per 2 13 0 m of floor area. The traps were placed on the floor in contact with the walls so that crawling as well as flying insects had access to the food. The traps remained in position during alternate periods of seven days. The traps were placed at the same position for each sampling period.

After each period the traps were removed and emptied into plexiglass boxes measuring 15 x 25 x 7 cm in the laboratory.

The plexiglass boxes with the contents were stored for 5 weeks in a room under conditions of 2 5.2 to 2 7.1°C and 5 6.4 to 7 9.7% RH for insect development. Adult insects emerging from the plexiglass boxes were counted after identification.

The experiment was initiated in February 197 8 and ran until the end of March, 1978.

II. Evaluation of Insect Traps in Warehouses

To detect and monitor insect pest populations of stored-cacao beans, the following insect traps were evalua­ ted: light traps, suction traps and sex pheromone traps. 20

Experiment 3 - Comparison of Fluorescent Lamps with

Different Wavelengths Operated

Simultaneously

This experiment was carried out in three different warehouses located in Ilheus.

The first test was conducted in a warehouse 27 x 40 x

5.7 0 m high, and was operated from April 18, 197 8 to April

25, 197 8. During this period there were 8,000 cacao bags in the building, each weighing 6 0 kg, infested with unknown numbers of insects associated with stored-cacao. The (R) Ellisco general purpose black light traps were placed

1.5 0 m apart in one corner of the building. The insect funnel entry was 4.5 0 m high. A piece of DDVP 2 0% insecti­ cide resin strip was placed inside the collection container.

Traps were operated from 5:00 PM to 8:00 AM. To reduce location effects on trap captures the treatments were rotated at random each day. The following 15-w Westing- (R) house fluorescent lamps were evaluated: a - F15T8/B; b - F15T8/BL; c - F15T8/BLB; d - F15T8/G; e - F15T8/GO; and f - F15T8/PK.

An analysis of variance was conducted considering a randomized block design with 7 replications of 6 treatments.

Data were transformed to / x + 1, and to / x when x t 0.

Transformed mean catches of species were compared by using

Duncan's multiple range test. 21

The second test was conducted in the same warehouse

from April 2 6 to May 3, 197 8. The traps were placed on one

of the longest sides of the building. They were placed

1.5 m apart, and the insect funnel entry was at a height of

1.0 m above the floor. The procedure and treatments were

the same as described in the previous test. However, there

were only 3,000 cacao bags in the warehouse at this time.

The treatments were replicated 6 times. The data were

anlaysed as in the first test.

The third test was carried out in another warehouse

14.50 x 40 x 5 m high, located on the pier of the old Ilheus

port. The test ran from May 4 to May 16, 197 8. The traps

were evenly distributed and placed with the funnel entry at

a height of 4.00 m. The treatments were also rotated at random each day. They were operated for 9 nights. At the

beginning of the test there were 8,0 00 cacao bags which were reduced to 1,000 at the time of the last reading.The

data were analysed as in the first test.

The fourth test was conducted in a warehouse 36 x 64 x

6 m high. The traps were placed at a height of 4.5 0 m and

operated from August 18, to September 2, 197 8. They were distributed as seen in Fig. 2 and randomly rotated 10 times.

There were only 5 treatments since the F15T8/GO was not included in this test. The warehouse was almost completely

filled with stacks of cacao bags. The data were analysed as previously described. 3 6 .0 0 m . iue . Positionlightof traps in warehouse. Figure 2. N3 N> 23

Experiment 4- - Comparison of Fluorescent Lamps with

Different Wavelengths Operated

Independently.

This experiment was carried out in a warehouse room 2 located in Ilheus containing 220 0 m of floor space and being 4 m high. One Ellisco (R ) general purpose black-light trap was operated from September 5 to December 8, 197 8.

Each day a lamp (treatment) was assigned at random to the trap. The following Westinghouse fluorescent lamps were evaluated: a -F15T8/B; b -F15T8/BL; c -F15T8/BLB; d -F1ST8/

G; e -F15T8/GO; f -F15T8/D; and g -F15T8/PK. Traps were operated from 5:00 PM to 8:00 AM. Insects entering the collecting container were killed with DDVP 2 0% resin strip.

An analysis of variance was carried out using a ran­ domized block design with 7 replications of 7 treatments.

The data were transformed to / x + 1 and the transformed mean catches of species were compared by Duncan's multiple range test.

Experiment 5 - Influence of Lamp Wattage on the

Catches of Insects Associated with

Stored-Cacao.

The experiment was conducted in a warehouse 36 x 64 x

6 m high, filled with stacks of cacao infested with unknown ( R) numbers of insects. Two Ellisco general purpose black light traps were used for the 15-w lamps, and two traps were 24 specially manufactured for the 3 0-w lamps. The latter traps were similar in shape to the preceeding. The traps were evenly distributed in the warehouse and' operated simultaneously from 5:00 P.M. to 8:00 A.M. The experi­ mental period was from November 1 to December 2, 197 8.

The following fluorescent lamps were evaluated: a -

F15T8/BL; b - F15T8/G; c - F30T8/BL; and d - F30T8/G.

To reduce location effects on trap captures the treatments were randomly rotated at each station.

The data were transformed to / x + 1 and to / x when x i 0, and analysed by using a two way analysis of variance with 17 replications of 4 treatments. The transformed mean catches of species were compared by Duncan's multiple range test.

Experiment 6 - Fluorescent Lamps and Sex Pheromone

Influence on Suction Traps Catches of

E . cautella.

The experiment was conducted in a store 36 x 64 x 6 m high, divided into five storage sections taking into account the position of the roof pillars. It was filled with stacks of cacao bags. C R) Six Century black light suction traps were used in this experiment. Two traps were fitted with the F15T8/BL lamp and two with the F15T8/G lamp while the remaining two traps had no lamps. A ten fiber dispenser of controlled 25 release vapor of the almond moth sex pheromone (PHE) was used for baiting the traps. The release rate of each dispenser was 17 yg/day at 21°C and 6 5% RH. The following treatments were evaluated: a - suction trap; b - suction trap + PHE; c - suction trap + F15T8/BL; d - suction trap

+ F15T8/BL + PHE; e - suction trap + F15T8/G; and f - suction trap + F15T8/G + PHE.

The traps were leveled at 4.5 0 m. Each section of the storage area was used for each replication. Within each section of the storage area treatments were assigned to traps at random. The traps were evenly distributed in each store section. The experimental period was from

December 5 to December 16, 1978.

Switches were turned-on to energize the circuits to the lamps and fan motor at 5:00 P.M. and turned-off at

8:00 A.M. The insects approaching the traps were drawn down by the suction and forced into the collecting bag below. After removing the collecting bags from the traps they were placed into killing jars. DDVP 2 0% resin strips were used as a killing agent.

The data were transformed to / and analysed as randomized block design with 8 replications of 6 treatments.

Mean transformed catches were compared by Duncan's multiple range test. 26

Although the experiment was initially designed for the almond moth, E. cautella, data on the cigarette beetle, L. serricorne and X. afer were also computed and analysed with 8 replications of each of the 3 treatments: suction trap, suction trap + F15T8/BL; and suction trap +

F15T8/G.

Experiment 7 - Effect of the Sex Pheromone Release

Rates on E. cautella Catches.

This experiment was carried out to determine the attraction of males to different release rates of the almond moth sex pheromone (Z)-9, (E)-12-tetradecadienyl acetate.

Two tests were conducted in the store described in

Experiment 6. Each storage area was used as a replication and replications were run simultaneously. The Pherocon (R) 1C traps (Zoecon Corp. ) were used for both tests. The bait consisted of controlled release vapor dispensers (R) (Conrel ), filled with the sex pheromone. Trapa were distributed equidistant within each storage area. Treat­ ments were assigned at random to the traps. Traps were elevated to 5 m and left in position for four days.

In the first test the following treatments were compared: a - 1.7 pg/day (1 fiber); b - 3. pg/day (2 fibers); c - 8.5 pg/day (5 fibers); d - 17.0 pg/day (10 fibers);e - Virgin Females (5 caged VF), and f - Control. 27

This test started on September 2 9 and was finished on October 3, 197 8. It was replicated 4 times.

A second test was conducted to compare different release rates of the pure sex pheromone of the almond moth. The following release rates were compared: a - 1.7 pg/day (1 fiber); b - 3.4 pg/day (2 fibers); c - 5.1 pg/ day (3 fibers); d - 6.8 pg/day (4 fibers); and e - Control.

This test period was from October 19 to October 23,

197 8 and was replicated 5 times.

The data from both tests were analysed after being transformed to/x, and the transformed mean catches compared by Duncan's multiple range test.

Experiment 8 - Effect of Height on the Sex Pheromone

« Trap Catches of E. cautella.

This experiment was carried out in the warehouse described in experiment 6. Traps were also the same, and were baited with a 10 fiber dispenser with commercial almond moth sex pheromone.

In each of the five warehouse sections four traps were placed at heights of 2, 3, 5 and 6 m over the center of the intersection of two alleyways between cacao stacks.

The intersecting passageways measured 2.8 m and 0.6 0 m in width. The stacks were 4.2 m high. The traps were left in position for four days from October 5 to October 9, 1978. 28

The data were transformed to / x and analysed as a completely randomized design and the transformed mean catches compared by Duncan’s multiple range test.

III. Chemical Control

Two experiments were conducted with th§ aim of determining the effectiveness of insecticides in reducing or controlling insect populations in bagged cacao.

Experiment 9 - Evaluation of Insecticide Sprays for

The Protection of Bagged Cacao.

The experiment started in February and was concluded in December, 197 8. It was carried out in a warehouse 12 x

2 0 x *+.5 m high, located in the Central Experimental

Station of CEPLAC in Ilheus. The experimental units were 2 arranged on one side of the warehouse occupying 60 m of floor space. At the outset 112 bags of superior cacao beans were fumigated with phosphine at the rate of 1 pellet of phostoxin (0.6 g) per 4- bags for 7 2 hours. The cacao beans had a moisture content of 6.6 per cent which changed to 6.8 per cent after ten months storage, showing some variation during the storage period ranging from 6.5 to 7.6 per cent.

The cacao bags were arranged in small stacks of 4 bags and 4 layers on wooden pallets according to a randomized 29

block design of the seven treatments with four replica­

tions. Stacks were 0.5 m apart from each other. The

treatments, along with the number of mg of active in- 2 gredients, applied per m were as follows: a -

Fenitrothion - 5 00; b - Fenitrothion - 750; c - Permethrin

- 250; d - Permethrin - 5 00; e - Pirimiphos methyl - 5 00;

f - Chlorpyrifos-methyl - 5 00; and g - Control.

Before each application of insecticide the bags from

each treatment were arranged in a layer on the floor of

the warehouse and their visible surfaces sprayed at a rate 2 of 100 ml/m . After spraying one side, the bags were

turned in order to spray the other side.

A knapsack hand operated sprayer fitted with a D3-13

TeeJet spray nozzle was used. After the sprayer was cali­

brated, dosages were based on the rate of flow for a given time. Insecticides were applied four times. Dates of application were: February 24, April 24, June 27, and

August 24, 1978.

Twenty four bags of downgraded cacao were placed on

the other side of the warehouse to provide a source of

infestation. Nine of the 24 downgraded cacao bags removed

for sampling had the following average number of insects:

T. castaneum - 22.1/bag, L. serricorne - 11.3/bag, A. advena - 0.33/bag, C. dimidiatus - 1.8/bag, and T. mauritanicus - 1.5/bag. 30

Insect infestation levels were assessed by menas of sieving the contents of bags. The sievings were placed in Berlese funnels for insect extraction. Insects were also hand sorted from the sievings after they were run through the Berlese funnels.

One bag from each stack was removed for sieving after

5, 7, 9 and 10 months of storage.

The data taken during the experiment were transformed to / x + 1, for the analysis of variance, and the means compared by Duncan's multiple range test.

Experiment 10 - Evaluation of Fumigation on Insect

Pests in Bagged Cacao using Phosphine.

The aim of this experiment was to determine the effectiveness of dosage rates of phosphine as compared to the standard dosage rate (1 pellet/5 bags for 7 2 hours) currently in use for the fumigation of cacao, in an attempt to reduce fumigant concentrations while still obtaining satisfactory control, and at the same time, reduce the time consignments remain in port before ship­ ment .

Eight stacks distributed in a warehouse in Ilheus were used. They were similar, twenty-layer stacks of 5 00 bags each. They were covered with plastic gas-proof sheets before distribution of phosphine pellets. The phosphine

fumigation was applied in the form of 0.6 g Phostoxin pellets. The treatment applied to the stacks were:

a - 1 pellet/4 bags for 48 hr; b - 1 pellet/5 bags for 48

hr; c - 1 pellet/6 bags for 48 hr; d - 1 pellet/5 bags for

72 hr; e - 1 pellet/6 bags for 72 hr; f - 1 pellet/7 bags

for 72 hr; g - Control for 48 hr; and h - Control for 7 2

hr.

The control stacks were only covered with the gas­ proof sheets. Pellets were placed in small wooden boxes.

Four boxes were placed on the floor in each side of the

stack.

Cacao bags were naturally infested with unknown numbers of insects. Infestation levels were assessed by sieving 1 the contents of 12 bags before and after fumigation as previously described. The bags were withdrawn from the upper four layers of each stack.

The data on insect counts from the assessment of infestation by sieving were transformed to / x + 1, and analysed by using a one way analysis of variance with 12 replications of 8 treatments.

The analyses were carried out for counts before and after fumigation. The transformed mean counts were com­ pared by Duncan's multiple range test a p = 0.05. 32

The percentage of control due to treatments was

estimated by using the Henderson and Tilton (195 5) formula:

Ta x Cb 100 1 “ Tb x Ca

In this formula, Tb is the number of insects in the bags before treatment, Ta the number of insects after treatment, Cb the number of insects from the control before treatment, and Ca the number of insects from the control after treatment. For treatment A, B and C, control data taken after 48 hrs were used in the calculations whereas for treatments D, E and F, control data taken after 7 2 hrs were used.

The experiment was initiated on March 1 and was finished on March 23, 1979 at the end of the cacao crop season. RESULTS AND DISCUSSION

Experiment 1 - Survey by Means of Sieving.

Results

Data presented in Table 1 shows that 2 6 8M- cacao bags were sampled for insect infestation at the port of Ilheus prior to shipment. More cacao bags were sampled in August and October than during the other months and most of the cacao bags came from the Center of the Cacao Region of

Bahia.

The foreign grain beetle, Ahasverus advena, was the insect pest most frequently found in the cacao bags, follow­ ed by the corn sap beetle, Carpophilus dimidiatus, the almond moth, Ephestia cautella, the red flour beetle,

Tribolium castaneum, the cigarette beetle, Lasioderma serricorne and the black fungus beetle, Alphitobius laevigatus. The parasitic Bracon hebetor was also found in the samples, usually in those infested with

Ephestia cautella larvae. The predatory anthocorid bugs,

Buchananiella sodalis and Xylocoris afer were also recorded in the samples (Table 2).

33 t

31+

Table 3 records the average number of insects per bag.

It was observed that the highest infestation was by A. advena.which averaged 12 insects per bag. Lower infesta­ tions were due to C. dimidiatus, E. cautella and T. castaneum.

The mean weight of the samples which consisted of debris plus fragmented cacao beans are presented in Table 4.

It was shown that sievings weight averaged 406 g. The samples obtained from cacao coming into the port of Ilheus from the north, center and south of the Cacao Region had an average mean weight of separated material (sievings) of 493,

347 and 417 g, respectively.

The highest weight of sievings was recorded in

February 1979 and averaged 649 g while the lowest weight was recorded in December 1978 and averaged 322 g (Table 4).

The data on the insects infesting bagged cacao allowed the determination of the percentage of bags free from insect infestation. Fig. 3 shows that of the cacao from the Northern Zone the highest percentage of bags not in­ fested was recorded in September 1978, whereas the lowest was observed in February 1979.

The curves in Fig. 4 show that the highest percentage of bags not infested was observed in August 19 7 8 in the

Central Zone, whereas the lowest occurred in March 197 9 and was due to the presence of A. advena and E. cautella. 35

In the Southern Zone the highest percentage of bags

not infested was observed in September 197 8, whereas the

lower percentage occurred in February 1979 (Fig. 5).

Fig. 6 shows the mean monthly E. cautella larvae

infestation of cacao bags coming into storage at the port

of Ilheus. Infestations of E. cautella were less than one

larva per bag in July, August, and September 19 7 8 in the

Northern, Central and Southern Zones of the Cacao Region.

In the Northern Zone, infestation was also less than

one larva per bag in October and December 1978. Infesta­ tion averaged one to three larvae in Hay and June 197 8 and

in January and February 197 9. The higher levels of in­

festation occurred in November 1978 and March 1979. .

The higher level of infestation by E. cautella in the

cacao bags coming into the port of Ilheus from the Central

Zone occurred in March 1979, averaging more than three larvae per bag. Population density was lower than two .

larvae per bag in the other months.

In the Southern Zone infestation averaged one to two larvae per bag in May 1978, and in January and February

197 9. As in the bags from the Northern Zone, the higher levels of infestation were observed in November 197 8 and

March 197 9. An average of more than four larvae per bag was observed in March 197 9 in the bags from this zone. 36

Population density of T. castaneum was low from May to December 197 8 and averaged less than one beetle per bag

(Fig. 7). Infestation increased in January 1979 and reached the peak in February, decreasing in March. Cacao coming from the Central and Southern Zones had an average of 9-10 T. castaneum per bag in February.

Fig. 8 shows the mean number of A. advena infesting cacao bags. A. advena was the most abundant species in the samples. Infestation was relatively low from May through

January, except for the bags from the North, which in

November 197 8, and in January 1979, had an average of 40-

5 0 and 2 0-3 0 beetles per bag, respectively. The highest level of infestation was observed in February 1979 with an average of ca. 2 00 individuals per bag in the cacao from the Southern Zone.

The highest population density of A. advena in the cacao bags from the Northern and Central Zones occured in

March 197 9. An average of 8 0-90 beetles was found in the cacao from the Central Zone and of 5 0-6 0 beetles per bag in the cacao from the Northern Zone.

Fig. 9 shows the mean numbers of C. dimidiatus in­ festing cacao bags. Again the highest population density was observed in February. However, the bags coming into storage from the Northern Zone were those most infested with this beetle and averaged more than 2 0 individuals per 37 bag. A peak of 7-8 individuals per bag was also observed in October of cacao originating from the South.

Infestation by all the beetles achieved a maximum in

February, whereas two peaks were observed for E. cautella: one in November 1978 and the other in March 1979 (Fig. 6).

The following parasites of grain pests were also recorded for the first time associated with stored-cacao in Bahia: Anisopteromalus calandrae (Howard) (:

Pteromalidae), Plastanoxus laevis (Ashmed) (Hymenoptera:

Bethylidae), and Holepyris sp. (Hymenoptera: Bethylidae).

The ichneumonid wasp, Venturia canescens (Gravenhorst), which also parasitizes E. cautella, was recorded in light trap catches.

Besides the insects already reported, psocids and mites were frequently found associated with stored cacao, and occasionally they were present in large numbers. Cock­ roaches , spiders and pseudoscorpions occurred in small numbers.

Discussion

The insect fauna associated with stored cacao in

Bahia is similar to the fauna found in the cacao producing countries of West Africa.

Data obtained in this survey showed that Araecerus fasciculatus, which was thought to be a major pest of stored cacao in Bahia (Silva, 1974), occurred only occasionally, 38

Table 1. Number of cacao bags sieved at the port of Ilheus before fumigation and shipment

Month Cacao Region of Bahia______Total North Center South

May 197 8 80 28 24 132

June 132 120 12 264

July 90 152 48 290

August 90 144 78 312

September 90 132 60 282

October 84 162 66 312

November 66 156 72 294

December 60 138 90 288

January 197 9 54 144 78 276

February . 48 66 30 144

March 18 54 18 90

Totals (all 812 1296 576 2684 months) 39

Table 2. Total numbers of insects collected from sievings of cacao bags.

Species Cacao Region of Bahia Total North Center South

A. advena 11495 13278 8275 33048

C. dimidiatus 1846 1794 1062 4702

E. cautella 946 1347 736 3029 ()

T. castaneum 619 1194 494 2307

L. serricorne 90 85 63 238

A. laevigatus 108 20 23 151

C. ferrugineus 15 44 3 62

T. mauritanicus 15 23 7 45

0. mercator 15 4 14 33

A. fasciculatus 11 10 5 26

0. surinamensis 7 0 1 8

Other Coleoptera 95 170 50 315

B. hebetor 307 643 328 1278 (Hymenoptera)

B. sodalis 97 245 134 476 (Hemiptera)

X. afer 28 18 10 56 (Hemiptera)

i 40

Table 3. Average number of insects per cacao bag from all the bags sampled at the port of Ilheus

Species Mean ± SE

A. advena 12.313 + 1.402

C. dimidiatus 1.752 + 0.207

E. cautella (Lepidoptera) 1.129 + 0. 065

T. castaneum 0.860 ± 0. 079

L. serricorne 0. 089 + 0.015

A. laevigatus 0.056 + 0. 019

C. ferrugineus 0. 023 + 0 .005

T. mauritanicus 0. 017 + 0.003

0. mercator 0. 012 + 0 .004

A. fasciculatus 0. 010 + 0. 003

0. surinamensis 0.003 + 0. 001

Other Coleoptera 0.117 ± 0. 010

B. hebetor (Hymenoptera) 0.476 + 0. 045

B. sodalis '(Hemiptera) 0.177 + 0.038

X. afer (Hemiptera) 0. 021 + 0.006 Table 4. Mean weight (g) of debris plus fragmented cacao beans obtained by sieving cacao bags.

Month Cacao Region of Bahia Total North Center South

May 197 8 466. 5 + 45. 5^ 340.4 + 35.8 556.7 + 187. 8 456.1 + 44. 4 June 582.9 + 47 .4 429.8 + 37.5 477 .5 + 69.1 508.5 + 29.6 July 617 .5 + 71.6 378 .5 + 28.0 400. 6 Hr 44.5 456.4 + 28.3 August 444.4 + 55. 0 323. 9 + 22. 8 459.1 + 38.3 392.5 + 21.5 September 509.3 + 44.1 338 .7 + 26.9 546. 7 + 50.3 437.4 + 22 . 3 October 369. 3 + 31.4 316. 8 + 20.6 322 . 3 + 31. 8 332 .1 + 15.2 November 331.1 + 27.1 322 . 6 + 24.4 320.3 + 21. 8 323.9 + 15.2 December 344. 7 + 25 . 3 290.4 + 16.1 354 .2 + 22.9 321.6 + 11. 9 January 197 9 517.2 + 62.8 269.9 + 14. 2 334.0 + 36.1 336.4 + 18.4 February 738.1 + 81. 9 509.4 + 52.5 812 .7 + 208.4 648.8 + 57.1 March 411. 7 + 42. 7 481.3 + 44. 7 383.9 + 48.3 447.9 + 29.9

Mean (all 492. 6 + 16. 6 347 .4 + 8.4 417.5 + 18.1 406.4 + 7.6 months)

— Mean ± SE.

-p I-* PERCENT 100 40 60 80 20 iue . ecnae fcco as o infested not bags cacao of Percentage 3. Figure oten oe fte aa Region. Cacao the of Zone Northern coming into the port of Ilheus from the from Ilheus of port the into coming 1978 L. serricorne dimidiatus C. casteneum T ddvena A. E. cautella E.

1979 42 PERCENT 100 iue . ecnae f aa bg nt infested not bags cacao of Percentage 4. Figure 40 60 20 80 — M J I eta Zn o h Cco Region. Cacao the of Zone Central coming into the port of Ilheus from the from Ilheus of port the into coming T casteneum T. o A. » Serricorne L. ■x C.dimidiatus »• . E. cautella E. . —r n— S A 1978 advena

T 0

N I j J j D I I l

1979 M F 43 PERCENT 100 iue . ecnae f aa bg nt infested not bags cacao of Percentage 5. Figure 60 40 80 20 1 0 — oten oe fte aa Region. Cacao the of Zone Southern coming into the port of Ilheus from the from Ilheus of port the into coming o x------x ------_____

m m • A. T o 1 E. • S A 1978 p dimidiatus serricorne odvena costeneum cautella ' 0 NM J J ! J ! D 1979 M F NUMBER PER BAG 0 L — iue . ennme fE cuel lra ifsigcco bags. cacao infesting larvae cautella E. of number Mean 6. Figure H CENTRAL □ 0

NORTHERN SOUTHERN

On -p NUMBER PER BAG 10 - 7 -4 - 4 6 0 - 3 - 5 - 9 8 p - - - -

iue . ennme fT csaemifsigcco bags cacao infesting castaneum T. of number Mean 7. Figure SOUTHERN I CENTRAL □ NORTHERN

CO -P El NORTHERN

□ CENTRAL

I SOUTHERN

M J J A S 1978 1979

Figure 8. Mean number of adyena infesting cacao bags.

-F NUMBER PER BAG 0 2 18 — 14 — 10 — 16 — 12 — o — o 4 — 4 6 — 6 2 — 2 — 8 J M n I Figure 9. Mean number of C. dimidiatus infesting cacao bags cacao infesting dimidiatus C.of number Mean 9. Figure ■ □ 0 SOUTHERN SSJk rrT~hi CO -p 49 in contrast to Ghana, Nigeria and Sao Tome where it is considered a major insect pest.

Although E. cautella was the third most abundant insect it can be considered as the main pest of stored- cacao, because the larvae feed inside the beans, not only causing direct damage but also contaminating the beans with webbing and feces. Besides, in the process of the grading of cacao for exportation by means of spear sampling, E. cautella is the main insect responsible for the defect classified as "weevily". If more than 2% of beans are classified as "weevily" in a cacao consignment, it is down­ graded from superior to "good fair", and cannot be ex­ ported under Brazilian regulations.

The abundance of the foreign grain beetle, Ahasverus advena can be ascribed to the presence of moldy cacao beans.

This beetle is a fungus feeder. According to Woodroffe

(1962) , 80% relative humidity is necessary for visible mold to develop. Thus, in terms of relative humidity/ moisture content equilibrium for cacao (Wilbaux, 1965), A. advena can develop when the moisture content of cacao beans is above 8%.

The second most abundant insect found in the samples was the corn sap beetle, Carpophilus dimidiatus. Its association with stored cacao can probably be explained by the presence of mold and volatile compounds in the cacao beans. In a field test carried out by Smilanick et al. 50

(197 8) it was shown that Carpophilus hemipterus, C. mutila- tus, C. freemani and C. lugubris were consistently attracted in large numbers to a three compound mixture of acetalde- hyde, ethyl acetate and ethyl alcohol, which have been found in the fermenting pulp as well as in the cacao beans and processing into chocolate (Alex D. Lopez, personal communication).

Another important insect of stored-cacao is the red flour beetle, T. castaneum which was the fourth most numerous in the samples. It develops in the particles of fragmented cacao beans. It contaminates cacao beans by its feces, undesirable odors, exuviae, and fragments. The highest level of infestation of T. castaneum occurred in

February 1979, in all zones of the Cacao Region (Fig. 7).

This level is coincident with the higher amounts of debris plus fragmented cacao beans which was also observed in

February (Table 4). The cigarette beetle, Lasioderma serricorne is less important in the cacao consignments coming into the port of Ilheus for exportation. However, it can develop in high numbers if cacao is stored for long periods, as demonstrated in the experiment on the protection of bagged cacao beans with insecticide sprays (Table 19).

The cacao bags of the untreated check were infested at an average rate of 109.7 beetles per bag after 9 months of storage, and 3 5.7 beetles per bag after 10 months of storage

(Table 20). 51

As it was shown in Figs. 3, 4 and 5, the highest

percentage of bags free from insect infestation were recorded in August/September decreasing through January.

February was the month when most of the cacao bags were

infested.

The cacao harvest in Bahia extends from April to

January. The early season crop or "temporao" is harvested from April to August and the main crop from September to

January. Most of the infestations found at the beginning of "temporao” crop, May to June, can be ascribed to the cacao harvested the previous crop season. On the other hand, the higher levels of infestation were observed in

February and March at the end of the crop season.

The chances that cacao bags for exportation become infested is greater at the end of the crop season than at the beginning, because insect population levels are high in the warehouses by the end of the crop season (Fig. 10).

Experiment 2 - Monitoring for Insect Pests in a Cacao

Warehouse using Food Traps.

Results

Table 5 shows the total number of insects caught in food traps placed in a warehouse in Ilheus. The insects caught in the food traps in order of decreasing abundance were T. castaneum, C. dimidiatus, L. serricorne, E. cautella, 52

A. advena, C. ferrugineus, A. laevigatus, Stelidota sp•,

Haptoncus luteolus and an unidentified species of Staphy- linidae. As illustrated in Fig. 10, the populations of stored-cacao insects fluctuate in a warehouse in Ilheus.

A population peak is evident in March followed by a strik­ ing decrease in April-May and a small increase from August through to October. A sharp increase began in December and another peak occurred in January. In February, a decline began and continued into March. Y Data presented in Fig. 11 show the seasonal abundance of E. cautella. The population was low in March, April and May. An increase was observed from June to August.

In August the first peak occurred. After a decrease from

September through November a second peak was reached in

December. A decrease began in January and continued through March.

Data on the beetles, T. castaneum, C. dimidiatus, A. advena and L. serricorne were computed together and the seasonal abundance presented in Fig. 12. A peak occurred in March and the numbers decreased from April through June.

In July and August no bettles were recorded in the food traps. In September, populations started increasing and achieved a maximum in January. A decline began in

February and continued through March. 53

Similar monthly trends were obtained for T. castaneum, C. dimidiatus and L. serricorne, as shown in

Figs. 13, 14 and 16. The population trend of A. advena is

shown in Fig. 15. A population peak occurred in March decreasing from April through to the end of June. No A_. advena were trapped in July and August. An increase in the population started in September and continued until

December. In January a striking decline was recorded which continued until the beginning of March.

The oriental rat flea, Xenopsylla cheops (Rothschild) was occasionally caught in the food traps.

Discussion

The population trends of the insects associated with cacao in a warehouse in Ilheus is shown in Fig. 10. The total population which is high in March drops suddenly and continues falling until June. This is a residual infesta­ tion of the crop season which started in April 1977 and ended in March 197 8. At the end of each crop season warehouses in Ilheus are cleaned, painted and sprayed. In

May 197 8 the warehouse where the experiment was located was sprayed with pyrethrum plus piperonyl butoxide.

After cleaning and spraying the cacao warehouse, few or no insects were caught in the food traps. The numbers of E. cautella started increasing in July/August (Fig. 11). 54

Table 5. Total insects caught in food traps in a cacao warehouse in Ilheus, from March 19 7 8 to March 197 91/.

• Insect species Number of insects

T. castaneum 3070

C. dimidiatus 1425

L. serricorne 1235

E. cautella 1064

A. advena 529

C. ferrugineus 18

A. laevigatus 9

Stelidota sp. 7

Haptoncus luteolus 2

Staphylinidae 2

All species 7361

—^ Six traps operating in 2 8 weeks. Figure 10. Seasonal abundance of stored cacao Seasonal storedabundanceof 10.Figure

Number of insects ( x 10 0 ) 12 18 - -I A J A S A J J M A M net i aeos i Ilheus,insects in inawarehouse Bahia. 98 I 1978 9 7 9 1

56

3

2

0 MAMJ J A S 0 N D ' J F M 1978 i 1979

Figure 11. Seasonal abundance of E. cautella in a cacao warehouse. Ilheus, Bahia.

18 -i o o 16 - X

12 - O« (/> C

•fr- 8 - o w 3E 4 - z

MAMJ JASONO|JFM 1978 I 1979

Figure 12. Seasonal abundance of beetles in a cacao warehouse. Ilheus, Bahia. 57

12

o 10 o 8 u M4> e 6

4 Es Z 2

0 MAMJ J AS ONDjj FM 1978 I 1979

Figure 13 Seasonal abundance of T. castaneum in a cacao warehouse. Ilheus, Bahia.

o 4 o

3 ue eat 2

Figure 1*+. Seasonal abundance of C. dimidiatus in a cacao warehouse. Ilheus, Bahia. 58

2

0

1978 I 1979

Figure 15. Seasonal abundance of A. advena in a cacao warehouse. Ilheus, Bahia.

o 4 o

3

4) -Q Ea Z 0

1978 1979

Figure 16 Seasonal abundance of L. serricorne in a cacao warehouse. Ilheus, Bahia. 59

However, the beetle numbers were low during the "temporao" crop, and started increasing at the beginning of the main-crop (Fig. 12).

The foreign grain beetle, A. advena, was not so abundant in the food traps although it was more abundant in the cacao bags. On the other hand, L. serricorne was caught in greatest number in the food traps mainly in

December, January and February, whereas few L. serricorne were collected from the sievings, suggesting that cacao for exportation was not stored for a long period.

The rusty grain beetle, Cryptolestes ferrugineus, was occasionally found'in the samples drawn at the port of

Ilheus, and in the food traps. This beetle also can be found in great numbers in warehouses where cacao is stored for long periods, as happened in the warehouse chosen for the experiments with light traps (Tables 6-8). Cacao had been in storage for 5 months when the light trap experi­ ments were initiated.

Experiment 3 - Comparison of Fluorescent Lamps with

Different Wavelengths Operated Simultaneously

Results

The date in Table 6 show that in warehouse A, higher numbers of L. serricorne, A. advena, C. obsoletus, C. ferrugineus, B. hebetor, and anthocorid bugs were captured by the traps placed M-. 5 m high fitted with the BL lamps 60

than by traps fitted with the B, BLB, G, GO and PK lamps.

Traps with the BL lamps captured fewer E. cautella than

traps with the G lamps, however, no statistically signifi­

cant differences were found between the collections.

Catches of L. serricorne, A. advena, C. obsoletus

and the anthocorid bugs were significantly greater in traps with the BL lamps than the catches in traps with the other

lamps. There was no significant differences between numbers of CL ferrugineus or JB. hebetor captured by traps equipped with BL and BLB lamps.

The numbers of insects captured in light traps placed

1 m high in warehouse A is shown in Table 7. During this test fewer cacao bags were stored than during the previous test. Catches were also lower than the catches in traps placed at 4-. 5 m high. During this test some T. castaneum were caught, whereas no E. cautella were captured.

Catches of C. obsoletus, T. castaneum, C. ferrugineus, A. advena, B. hebetor and the anthocorid bugs were more numerous in traps with the BLB and BL lamps. L. serricorne was captured in higher numbers in traps with the G lamp, although no significant differences were found with the other traps.

There were no statistically significant differences among the numbers of anthocorids caught by the traps with the BL, BLB, B and G lamps. Table 8 shows the results of insects collected in

light traps placed 4 m above the floor in warehouse B.

The beetles L. serricorne, T. castaneum and A. advena were

more attracted to BL lamps. C_. ferrugineus was more

attracted to BLB. No significant differences were found

among catches of these beetles in traps with the BL and

BLB lamps. B. sodalis was the only species of anthocorid

bug infesting bagged cacao in this warehouse. Traps with

the B lamps caught greater numbers of B. sodalis, although

no significant differences were found among captures in

traps with the B, BLand the BLB lamps.

Traps placed at 4.5 m captured more E. cautella in warehouse C than in warehouse A except for the traps with the PK lamp (Table 9). The GO lamp was not included in

this test. The' results in Table 9 show that the B and G

lamps caught more moths than the other lamps. However, no

significant differences were found among the B, BL, BLB and

G lamps. Traps with the PK lamp captured fewer E. cautella than the other traps.

Discussion

The effectiveness of different light sources in attracting stored-products insects has been examined

(Stermer, 1959; Soderstrom, 1970a, 1970b; Kirkpatrick et al.

1970; and Hagstrum et al., 1977). Except for the work by Table 6. Mean numbers of insects caught in light traps operated simultaneously 4.5 0 m high in cacao warehouse A. Ilheus, Bahia, April, 19781/

Light traps fitted with lamps Insect B BL BLB G GO PK

E. cautella 1.282 a—^ 2 .115 be 1.549 ab 2.216 c 1.647 abc 1. 703 abc

L. serricorne 2 .051 b 3.193 c 2.061 b 1.749 ab 1.282 a 1.425 a

A. advena 4.238 c 7 .884 e 5. 319 d 3.513 be 1.580 a 3.216 b

C. obsoletus 2 .606 a 14.925 c 8.120 b 1.327 • a 1.177 a 2 .384 a

C. ferrugineus 7 .470 c 11.967 d 10.989 d 3.729 a 3.927 a 5.784 b

B. hebetor 4.510 be 12 .952 d 12.072 d 5 .224 c 2 .170 a 2.638 ab 3 / Anthocoridae— 2 .791 b 5.707 d 4. 602 c 3.115 b 1.783 a 2 .329 ab

— ^ Insect numbers transformed to / x + 1.

2/ — Means for each insect species followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test. 3 / — Includes Buchananiella sodalis and Xylocoris afer.

CD N) Table 7. Mean numbers of insects caughts in light traps operated simultaneously 1.00 m high in cacao warehouse A. Ilheus, Bahia, April-May, 197 82/

Light traps fitted with lamps Insect B BL BLB G GO PK

L. serricorne 1.451 ai/ 1.602 a 1.236 a 1.672 a 1.069 a 1. 343 a 3/ C. obsoletus 1.624 a— 3. 807 b 4.358 b 1.191 a 1. 313 a 1.236 a

T. castaneum 1. 275 ab 1. 761 b 1.707 b 1.122 a 1.138 a 1.429 ab

C. ferrugineus 4. 514 a y 6.431 a 5. 645 a 2.924 a 2 .492 a 2 .898 a

A. advena 3.295 be 3.471 be 4.217 c 2.591 ab 1.565 a 2 .837 b

B. hebetor 1.632 a 4.308 be 4.445 c 2.917 ab 1.604 a 1.715 a 4/ Anthocondae— 3.330 b 3 .682 b 3.483 b 2.810 b 1.736 a 2 .032 a

— Insect numbers transformed to / x + 1.

—2 / Not significantly different by the F test. 3/ — Means for each insect species followed by the same letter are not significantly different (p = 0.05). Duncan’s multiple range test. 4 / — Includes Buchananiella sodalis and Xylocoris afer. CT> CO Table 8. Mean numbers of insects caught in light traps operated simulti 4.00 m high in cacao warehouse B. Ilheus, Bahia, May, 1978.± ‘

- Light traps fitted with lamps Insect B BL BLB G GO PK

L. serricorne 3.163 bci/ 3.758 c 2.819 abc 2.435 ab 1. 904 a 2 .476 ab

T. castaneum 1. 311 ab 1.899 c 1.675 be 1.092 a 1. 046 a 1.161 a

A. advena 11.702 c 14.978 d 12.448 cd 6.253 b 2.737 a 5. 873 b

C. ferrugineus 4.698 ab 5.387 b 5.425 b 3.242 ab 2 . 306 a 2 .624 a

B. sodalis 7 .531 c 6.118 be 6.741 be 5.319 b 3.373 a 3.129 a

— Insect numbers transformed to / x + 1.

2/ . ... — Means for each insect species followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test.

CD -P 65

Table 9. Mean numbers of E . cautella caught in light traps operated simultaneously 4.5 m high in cacao warehouse C. Ilheus, Bahia, August - September, 197 8 .

Mean numbers of Mean of transformed Lamps moths caught insect numbers^

2 / F15T8/B 1 0 . 6 3.2 81 a-

F15T8/BL 7.9 2.906 a

F15T8/BLB 7.9 2 .934 a

F15T8/G 1 0 . 8 3.279 a

F15T8/PK 1 . 8 1.598 b

—^ Moth numbers transformed to / x + 1.

2 / — Means followed by the same letter are not signifi­ cantly different (p = 0.05). Duncan's multiple range test. 66

Soderstrom. (197 0a) in empty and peanut-filled warehouses most other studies were done in test chambers or labora­ tory rooms with insects from cultures and the lamps used were also different from those used in the present study.

No references regarding the effectiveness of fluorescent lamps in attracting A. advena, C. obsoletus, C. ferruginous, B. hebetor, and the anthocorid bugs were found.

As has already been reported, Stermer (195 9) and

Kirkpatrick et al. (1970), E. cautella preferred the green or the black light lamp. Although moths were seen flying in the warehouse, the numbers caught in the traps were low.

It seems that the Ellisco (R) light-trap used in this experiment is not as effective as the suction-light trap used in experiment 6 .

Hagstrum et al. (19 77) found that when green or black light lamps were combined with a suction trap,.an increased number of the almond moth, E. cautella was captured. Table

9 shows that no significant differences were found in the effectiveness of lamps B, BL, BLB and G in attracting E. cautella although the green and the blue lamps were the most attractive.

The beetles A. advena and C. obsoletus preferred the

BL lamp but the BLB was also effective in catching them when the traps were placed 1 m above floor level in the warehouse. 67

Fewer insects were captured in the traps when they were placed at 1 m from the floor in the warehouse, probably because most of the activity of flying insects occurs above this level as was shown for E. cautella which was caught in higher numbers in sex pheromone traps placed above the level of the stacks (Table 17) .

All traps attracted B_. hebetor in great numbers although those traps with BL and BLB lamps were the most effective. The BL and BLB lamps were equally effective.

The rusty grain beetle, C. ferrugineus also showed no preference for either the BL and BLB lamps. When the traps were placed on the floor it was captured in lower numbers, with no statistical difference among the numbers captured in traps with the B, BL, BLB and G lamps.

The anthocorid bug, Buchananiella sodalis prefer a waveband ranging from ultraviolet or BL to the blue portion of the spectrum. However the highest number was captured by the trap fitted with the blue lamp. A preference for the BL lamp was shown when both the anthocorid bugs,

Xylocoris afer and B. sodalis were counted together. An experiment to determine the preferred waveband for X. afer would be advantageous. !

68

Experiment 4- - Comparison of Fluorescent Lamps with

Different Wavelengths Operated

Independently.

Results

Table 10 shows the results of insects captures in

light traps operated independently in a warehouse in

Ilheus. Traps fitted with the BL lamp captured more E.

cautella, C. obsoletus, B. hebetor and Bethylidae wasp,

whereas the traps with the D lamp captures more L. serri-

corne.

•There were no statistically significant differences

between catches of E. cautella, L. serricorne, B. hebetor

and Bethylidae in the traps used., The numbers of C. obsoletus caught in traps with the BL and BLB lamps were not significantly different, but the number of C. obsoletus caught was greater for the trap with lamp BL than for traps with the B, G, GO, D and PK lamps.

The wasp, B_. hebetor, was very abundant during the experimental period and it was captured in high numbers in the traps.

Discussion

The beetle, Carpophilus obsoletus again showed a preference for the BL and BLB lamps, supporting the data obtained in the previous experiment. Although the BL lamp was more attractive to such insects as B. hebetor, E. Table 10. Mean numbers of insects caught in light traps operated independently i] the Gerais cacao warehouse. Ilheus, Bahia, September-December, 197 8.—

Light traps fitted with lamps Insect B BL BLB G GO D PK

E. cautella 2.035 a y 2 .125 a 1.634 a 1.867 a 1.552 a 1.645 a 2 . 030 a

C. obsoletus 2 .21 0 ab—^ 3.268 c 3.031 be 1. 547 a 2 .110 ab 2 .050 ab 1.626 a

2 / L. serricorne 3. 341 a— 2 .704 a 2 . 963 a 3. 302 a 3 .609 a 3 . 831 a 3.109 a

B. hebetor 24.001 a 27 .572 a 26.169 a 18.975 a 19 .586 a 22 .842 a 16.024 a 4/ Bethylidae— 5.201 a*' 5.633 a 5 . 010 a 4. 369 a 3.878 a 3 .711 a 2 .300 a

—^ Insect numbers transformed to / x + 1.

—2 / Means for each insect species not significantly different by the F test. 3/ — Means for each insect species followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test.

—4/ Includes Plastanoxus laevis • and Holepyns sp.

CD CD 70 cautella and Bethylidae wasps, no significant differences were shown among treatments. Data on L. serricorne also showed no significant differences among treatments.

The wasp, B. hebetor which parasitizes the larvae of

E. cautella, was the most abundant insect captured in the warehouse. Due to its abundance we would also expect a much higher number of E. cautella being captured in the traps, however, this did not happen. Again, it seems that the trap model used is not effective for collecting the adult of E. cautella inside the cacao warehouse.

Experiment 5 - Influence of Lamp Wattage on the Catches of

Insects Associated with Stored-Cacao.

Results

Results of the captures of insects caught by light traps with 15-w and 3 0-w lamps are given in Table 11. The mean numbers of E. cautella, L. serricorne, C. obsoletus,

B. hebetor, X. afer and Bethylidae wasps captures were greater in the trap with the F30T8/BL lamp than in the trap with the F15T8/BL lamp. No differences in A. advena numbers were found between captures in traps with the

F15T8/BL and F30T8/BL lamps.

The wattage of the green lamps had no influence in the numbers of E. cautella, L. serricorne, A. advena, C. obsoletus and B. hebetor captured. There was, however, a 71

Table 11. Insects captured in light traps as influenced by the lamp wattage. Ilheus, Bahia, November-December, 197 8.

Mean numbers of -insects captured in traps fitted withi' Insect F15T8/BL F30T8/BL F15T8/G F30T8/G

E. cautella 1 . 6 6 6 aiy 2 .771 b 1.721 a 1.836 a

L. serricorne 1.4-7 6 a 2 .309 b 2 .362 b 2 .420 b

A. advena 2 .692 a 3 .466 ab 4.107 b 4.187 b

C. obsoletus 4.096 b 12 .267 c 1. 561 a 2 .414 ab

B. hebetor 22.923 a 42.175 b 13 .790 a 22.444 a

X. afer 1.189 a 3 . 557 c 1.450- ab 2 . 024 b

Bethylidae—^ 4. 910 a 8 .248 b 4.170 a 7 .374 b

—^ Insect numbers transformed to / x + 1.

—2 / Means for each insect species followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test.

3 / — Includes Plastanoxus laevis and Holepyris sp. 72 significant difference in the numbers of Bethylidae wasps captured.

Of the four lamps used, the F3 0T8/BL lamps were the most attractive for E. cautella, C. obsoletus, B. hebetor,

X. afer and Bethylidae wasps. The F30T8/G lamp attracted more L. serricorne and A. advena.

Discussion

Data presented in Table 11 show that with the in­ crease in lamp wattage more insects were captured in the traps. However, green lamps of greater wattage did not differ significantly from the standard 15-w except in the case of the bethylid wasps.

The captures of L. serricorne and A. advena increased two-fold in traps with a 3 0-w BL lamp. However, the in­ crease in the numbers of the other insects captured was not in direct proportion with the increase in lamp wattage.

The numbers of E. cautella, B. hebetor and Bethylid wasps captured in the traps with a 3 0-w BL lamp was roughly 3 times greater than in the traps with a 15-w BL lamp.

Similarly, nine times more C. obsoletus and X. afer were caught with the more powerful lamp. 73

Experiment 6 - Fluorescent Lamps and Sex Pheromone

Influence on Suction Trap Catches of E.

cautella.

Results

The mean numbers of moths caught per trap is given in Table 12, together with the means of the transformed moth counts. E. cautella was captured in greatest numbers in traps baited with the sex pheromone. Suction traps baited with PHE captured more moths than the traps with the

BL and G lamps baited with the PHE, although no significant differences were found among them.

Traps with the BL lamp and traps with the G lamp captured more moths than the suction trap alone. However, no significant difference was found between the suction trap and the suction trap plus the BL lamp. Captures were greater for the suction trap with the G lamp than for the suction trap alone.

Data on the influence of fluorescent lamps on suction traps catches of L. serricorne and of the anthocorid bug,

X.afer, was also obtained in this experiment. They were computed and analysed taking into account two traps for each treatment. Thus, the catches in the suction traps baited with the PHE were added up to the catches in the suction traps without PHE. 74

Results of the mean numbers of L. serricorne caught

per suction trap together with the means of transformed

counts were reported in Table 13. Captures of L. serri­

corne were greater for suction traps with the G and BL

lamps than for suction traps alone. The suction trap with

the G lamp caught more L. serricorne than the suction trap with the BL lamp, although no significant difference was

found between the catches.

Table 14 shows the results of the mean numbers of X.

afer captured per suction trap, together with the means of transformed counts. Captures of X. afer were fewer for the suction trap plus the G lamp and the suction trap alone than for the suction trap plus the BL lamp.

Discussion

Although no experiments were conducted to compare

light traps with and without suction, data presented in

Table 12 suggest that suction traps fitted with fluorescent lamps were more effective in capturing E. cautella than traps with fluorescent lamps but without suction.

It was shown that the sex pheromone used as bait in­ creased the effectiveness of the suction traps, thus, it can be a useful tool in the monitoring of E. cautella populations. Haines (1976), discussing the prospects for the use of synthetic sex pheromone for pest management in 75

Table 12. Mean numbers of E. cautella caught per trap in a cacao warehouse. Ilheus, Bahia, December, 1978.

Mean numbers Mean of transformed Traps of moths moth counts — 7

Suction-trap 16. 5 3.611 ai'

Suction-trap + PHE- 7 61.2 7 .710 c

Suction-trap + BL 24.2 4.653 ab

Suction-trap + BL + PHE 46. 6 6 . 6 6 6 c

Suction-trap + G 29.0 5.148 b

Suction-trap + G + PHE 47.7 6.694 c

— 7 Moth numbers transformed to / x.

2/ — Means followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test.

3 / — Traps were baited with ten fibers containing the sex pheromone (release rate of 1.7 pg/day at 21 C). 76

Table 13. Mean numbers of L. serricorne caught per trap in a cacao warehouse. Ilheus, Bahia, December, 197 8.

Mean numbers Mean of transformed Traps of insects insect counts —^

Suction-trap 6.87 2.378 ay

Suction-trap + BL 4*+ . 75 5. 783 b

Suction-trap + G 51.87 6.595 b

— ^ Insect counts transformed to / x

2 / — Means followed by the same letter are not significantly different at 5% level according to LSD test.

Table 14. Mean numbers of the anthocorid bug, X. afer caught per trap in a cacao warehouse. Ilheus, Bahia, December, 197 8 .

Mean numbers Mean of transformed Traps of bugs bug counts —^

2 / Suction-trap 3.37 2.07 3 a-

Suction-trap + BL 66.25 7.475 b

Suction-trap + G 12 .37 3.490 a

—^ Bug counts transformed to / x .

—2 / Means followed by the same letter are not significantly . different at 5% level according to LSD test. 77

stored- products situations, stated that this technique

could be very useful for detecting very low levels of E.

cautella in stores.

Data from unbaited suction light traps also corrobor­ ate the results on light attractiveness to E. cautella

obtained in experiments 3 and 4 with light traps. They

also agree with the results obtained by Stermer (195 9) ,

Soderstrom (1970) and Kirkpatrick et al. (1970).

The suction traps fitted with fluorescent lamps were more effective in collecting L. serricorne, as shown in

Table 13. In this experiment both the BL and G lamps were equally effective in collecting L. serricorne, however,

Kirkpatrick et al. (197 0) and Soderstrom (1970) reported that L. serricorne responded in fewest number to green light. On the other hand, suction traps with the BL lamp increased collections of X. afer by almost 2 0 fold.

Experiment 7 - Effect of the Sex Pheromone Release Rates

on E. cautella Catches.

Results

Results on the effect of release rates of the phero­ mone on the E. cautella catches are presented in Tables 15 and 16.

The adhesive traps baited with the virgin females captured approximately 2.3 and 9 times more moths per trap 78

than traps baited with the sex pheromone dispensers and

the control traps respectively. Traps baited with the sex

pheromone dispensers captured approximately 3.8 times more

moths per trap than the control traps.

There were no significant differences in the mean

numbers of moths caught in the traps baited with the

various release rates of the sex pheromone used.

Table 16 shows the results of the mean numbers of E.

cautella caught in traps baited with different release

rates of the pure (Z) — 9 (E)-1 2 -tetradecadienyl acetate.

Captures of E. cautella were significantly higher in traps

baited with the sex pheromone than in the control traps.

No significant difference was found in the mean numbers of

E. cautella captured in the traps baited with the sex

1 pheromone. Approximately 6.9 times more moths were cap­

tured in traps baited with the sex pheromone than in the

control traps.

The mean numbers of E . cautella per trap caught in the traps baited with the pure (Z,E)-9, 12 tetradecadienyl acetate (Table 16) was 2.2 times higher than in traps baited with the commercial sex pheromone (Table 15) . How­ ever, it is essential to take into account that data

shown in Tables 15 and 16 were obtained in separate trials.

Therefore, in a future study it would be interesting to compare the commercial and the pure sex pheromones. 79

Table 15. Mean numbers of E. cautella captured per trap in a cacao warehouse. Ilheus, Bahia, September-October, 1978.

Mean number Mean of transformed Treatments captured moth counts—^

1 fiber —^ 82.5 8.944 a-

2 fibers ’ 90.0 9.438 a

5 fibers 80.5 8.952 a

10 fibers 92.5 9.526 a

Virgin females (5 VFs.) 197.7 13.568 b

Control 2 2 . 2 4.594 c

—^ Moth counts transformed to / x.

2 / — 1 fiber has a release rate of 1.7 pg/day of the almond moth sex pheromone at 21°C, and 6 5% R.H.

3 / — Means followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test. 80

Table 16. Mean numbers of E. cautella captured in traps baited with the pure sex pheromone. Ilheus, Bahia, October, 197 8 .

Mean numbers Mean of transformed Treatments captured moth counts —^

2 / 1 fiber — 218. 8 14.5 93 a -

2 fibers 183. 6 12 .999 a

3 fibers 177 .8 12 .969 a

4- fibers 2 0 0 . 0 13.816 a

Control 28.2 5.257 b

—^ Moth counts transformed to / x.

2 / o — 1 fiber has a release rate of 1.7 pg/day at 21 C, and 65% R.H.

3 / — Means followed by the same letter are not signifi­ cantly different (p = 0.05). Duncan's multiple range test. 81

Discussion

Reichmuth et al. (197 8 ) found that in stores densely- infested with E. elutella approximately 1.6 times more moths were captured in the pheromone traps than in the control traps. Further, in slightly infested stores this ratio increased to 9.

In the present experiments carried out in cacao stores in Bahia with E. cautella, the pheromone traps caught 6.9 and 3.8 times more moths than the control when using the purified and the commercial sex pheromone, respectively.

The sex pheromone doses per capsule from the experi­ ments in Germany were 3.3 yg and 5 2.4- yg of (Z,E)-9, 12 tetradecadienyl acetate, whereas the release rates of the dispensers from the experiments in Bahia ranged from 1.7 yg to 17 yg of the sex pheromone per day.

The room pheromone dosage rate used in the German warehouses were 1.7 yg and 2 0 yg of the sex pheromone per 3 1 0 0 m in warehouse 1 and warehouse 2 , respectively.

In Bahia, the room pheromone dosage were not uniform since different release rates per dispenser were used in the same cacao warehouse. However, the room pheromone dosages were approximately 1.7 yg, 3.4 yg, 8.5 yg and 17 yg 3 of (Z,E)-9, 12 tetradecadienyl acetate per 500 m m the first test (Table 15) using the commercially prepared t

82 attractant, and 1,7 yg, 3.1+ yg, 5.1 yg and 6. 8 yg using 3 . the purified sex pheromone per 5 00 m xn the second test

(Table 16). The dosage rates were thus higher in the

German studies with E. elutella than in the present study with E. cautella. From Tables 15 and 16 it can be seen that the pure sex pheromone seems to be more effective than the commercial sex pheromone, although no experiment was conducted to compare the two. In the first test

(Table 15) the traps with the natural sex pheromone re­ leased by the virgin females captured 2.3 times more moths than the traps with the fibers. The higher numbers of moths collected in the traps with the virgin females can probably be explained by the effectiveness of the naturally occurring ratios of the components of the sex pheromone complex of

E. cautella. The naturally occurring ratios of the three components of the sex pheromone complex of E. cautella have already been determined by Read and Beevor (1976).

As shown in Tables 15 and 16, it seems that the pure

(Z,E)-9, 12 tetradecadienyl acetate was more effective than the commercial sex pheromone. The purified almond moth sex pheromone contained 1% or less of the ZZ-isomer (J . H.

Tumlinson, personal communication), whereas the commercial sex pheromone, which was obtained from Conrel, contained

15% of the ZZ-isomer and 4-5% of other impurities. 83

Increasing the release rate by using more fibers had no significant effect on the numbers of E. cautella cap­ tured (Tables 15 and 16).

Experiment 8 - Effect of Height on the Sex Pheromone

Trap Catches of E. cautella.

Results

Table 17 presents the mean numbers of E. cautella caught in adhesive traps baited with sex pheromone, placed at different heights , together with the means of trans­ formed moth counts.

Traps placed at a height of 6 m captured the highest number of E. cautella, followed by 5 m traps. No signifi­ cant difference was found between the numbers of moths captured at these two heights. Traps placed between alleyways at heights of 2 and 4 m high captured fewer moths than the traps placed above stack level at heights

5 and 6 m high. There were no statistical differences among the means of moths captured in traps placed at heights 2, 4 and 5 m in the warehouse.

Discussion

An idea of the catches of E. cautella at different heights in a cacao warehouse is given in Table 17. The catches were greatest in the upper portions in the 84

Table 17. Mean numbers of E. cautella caught on sex pheromone baited traps at different heights in a cacao warehouse. Ilheus, Bahia, October, 197 8 .

Mean numbers Mean of transformed Heights captured moth captured—^

2 / 2 m 27.8 4.9 44 a -

4 m 38.2 6.139 a

5 m 41. 0 6.379 ab

6 m 65.0 7.981 b

Moth numbers transformed to / x .

2 / . — Means followed by the same letter are not signifi­ cantly different Cp = 0.05). Duncan's multiple range test. 85

warehouse, above the stacks level. Fewer moths were

caught in traps placed at alleyway intersections.

It could be postulated that fewer moths were caught

at lower levels in the cacao warehouse, because less flying

space was available due to the presence of the stacks.

There was also a smaller air space for diffusion of the

pheromone at the lower levels. However, Graham (197 0) also

obtained similar results in maize stores using flight

traps. He showed that the greatest flight activity of E .

cautella occurred high in the store where temperature is higher near the roof and explained that temperature gradi­

ent from floor to roof is probably the main factor influ­

encing moth activity. The flight activity and resting apparently occurs in a restricted temperature zone.

Experiment 9 - Evaluation of Insecticide Sprays for the

Protection of Bagged Cacao.

Results

Table 18 shows the results of the effect of insecti­ cide sprays against attack of insects on bagged cacao beans.

After five months there were no live insects in bags treated with chlorpyrifos-methyl and few insects were collected in bags treated with the other insecticides.

Insect numbers were higher in bags treated with fenitrothion 2 at a dosage rate of 500 ^g a.i./m than m the other 86

treated bags.

After seven months of storage infestation had in­

creased in the untreated cacao bags. There were some

insects alive in cacao bags treated with both dosages of

fenitrothion and permethrin. Infestation was very low in

bags treated with chlorpyrifos-methyl, whereas there were

no live insects when pirimiphos-methyl was sprayed.

After nine months of storage, infestations were still

increasing in the untreated bags but declined after the

10th month. For all periods up to 10 months of storage

there were significantly higher numbers of insects in the

untreated than in the treated bags.

In the last month of storage, data on insect species

such as Carpophilus dimidiatus and Tenebroides mauritanicus were included in the analyses, because they were present in the untreated bags. Two other specimens of C. dimidiatus 2 were found in a bag treated with permethrin 25 0 mg a.i./m .

Since T. castaneum and L. serricorne were the dominant

species at all times, a separate analysis was made of their numbers after nine and ten months of storage (Table 19) .

After nine months, few T. castaneum were alive in the treatments except for the bags treated with permethrin 2 (250 mg a.i./m ). Population density of L. serricorne was ca. three times higher than population density of T. castaneum. There were no L. serricorne in the bags treated 87

with either dosages of permethrin, and a few were

collected from bags treated with the other insecticides,

however, there was an average of 3 cigarette beetles per 2 bag sprayed with fenitrothion at 75 0 mg a.i./m .

Population density of T. castaneum was higher than

population density of L. serricorne in the untreated bags

ten months after they had been sprayed. There was a statistically significant difference between the infesta­

tions of the treated and untreated bags. L. serricorne

appeared in higher numbers in bags sprayed with fenitro- 2 thion 5 00 mg a.i./m , than in the other treatments,

although there were no statistically significant differences

among treatments.

Discussion

The first assessment of infestation level was conducted after 5 months of storage. During this storage period

infestation in the untreated bags was low, with an average of 9 insects per bag.

The insect species recorded in the cacao bags were the same as those infesting the 24 downgraded cacao bags used as a source of infestation. Nine of the 24 downgraded cacao bags removed for sampling were infested with the following species: T. castaneum, L. serricorne, C. dimidiatus, T. mauritanicus, and A. advena. Although Table 18• Means of transformed insect counts following application of insecticides to cacao bags. Ilheus, Bahia, February, 197 8 - December, 197 8 . V

2 Period of cacao storage Treatments a.i./m rri------5-7------57 (mg) 5 months— 7 months— 9 months— 10 months—

Fenitrothion 500 1.772 1.161 a 1.846 a 3.265 a Fenitrothion 750 1. 354 a 1. 537 a 2.505 a 2 .158 a Permethrin 250 1.287 a 1. 287 a 1.104 a 1. 594 a Permethrin 500 1.183 a 1.207 a 2 .249 a 1.722 a Pirimiphos- methyl 500 1.183 a 1 . 0 0 0 a 1 . 862 a 1.561 a Chlorpyrifos- methyl 500 1 . 0 0 0 a 1.104 a 1.596 a 1.390 a

Untreated check - 3. 099 b 5 . 335 b 11.778 b 9.013 b

—^ Raw insect numbers transformed to / x + 1. 2 / — Includes E. cautella + T. castaneum + L. serricorne + A. advena. 3/ — Includes E. cautella + T, castaneum + L. serricorne + A. advena + C. dimidiatus + T . mauritanicus.

—^ Means followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test.

OO 00 Table 19. Means of transformed L. serricorne and T. castaneum counts following application of insecticides to cacao bags. Ilheus, Bahia, February - December, 197 8 . \f

Period of cacao storage

Treatments a.l./m• / 2 9 months 10 months (mg) LS— 7 TC LS TC

3/ Fenitrothion 500 1.250 a— 1.104 a 2 .964 a 1.287 a Fenitrothion 750 1.809 a 1. 354 a 1.675 a 1.287 a

Permethrin 250 1 . 0 0 0 a 1 . 00 0 a 1.183 a 1.183 a

Permethrin 500 1 . 0 0 0 a 1.287 a 1 . 00 0 a 1. 516 a Pirimiphos- methyl 500 1.537 a 1. 354 a 1.104 a 1.411 a Chlorpyrifos- methyl 500 1.104 a 1. 366 a 1.104 a 1. 207 a

Untreated check - 10.163 b 5.139 b 5.570 b 6.196 b

—^ Raw insect numbers transformed to / x + 1. 2 / — LS = L. serricorne; TC = T. castaneum. 3 / — Means followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test.

00 CO 90

Table 20. Number of insects collected in the four untreated bags sampled at different periods of storage. Ilheus, Bahia, February - December, 197 8.

Period of storage Insects 5 7 9 10 months months months months

E. cautella 3 3 5 6

T. castaneum 18 28 121 161

L. serricorne 14 77 439 143

A. advena 1 2 0 0

C. dimidiatus 0 0 0 24

T. mauritanicus 0 0 0 7

Total 36 110 565 341 91

E. cautella was not found in this sample of nine, it was

found in very low numbers in'the bags in the experiment.

The bags were left in storage for five months after

fumigation to allow time for a buildup in insect infesta­

tions. Table 18 shows that there was a marked level of

infestation in the untreated check after five months.

Assessments of infestation were also made after 7 , 9

and 10 months of storage. The insect populations in the

untreated bags increased with the time of storage (Table 18)

except for L. serricorne whose infestation level was higher

in the bags sieved after 9 months of storage than in the

bags sieved after 10 months of storage (Table 19). The

decrease in number of L. serricorne after ten months of

storage could be due to the presence of T. mauritanicus which in the larval and adult form is a voracious predator

on L. serricorne larvae (Riley, 1969b).

A high proportion (up to 8 9 per cent) of the insects in the untreated bags were T. castaneum and L. serricorne after five months of storage (Table 2 0). This proportion increased up to 9 5 and 99 per cent after 7 and 9 months of

storage, respectively, then decreased again to 8 9 per cent after 10 months storage (Table 2 0). This decrease in percentage was due to the presence of T. mauritanicus and

C. dimidiatus, which had not been collected in the earlier

samples, as well as a decrease in the numbers of L. 92

serricorne. As much as 64 per cent of all the insects

collected in the cacao bags were the cigarette beetle, L.

serricorne. For all species, it can be seen in Table 18

that cacao bags treated with chlorpyrifos-methyl, and

pirimiphos-methyl, and permethrin were less infested than ■

the bags treated with fenitrothion, although no statistical

differences were found among treatments. The bags treated 2 with permethrin at a dosage rate of 5 00 mg a.i./m were not infested with L. serricorne (Table 19).

Experiment 10 - Evaluation of Fumigation on Insect Pests in

Bagged Cacao Beans using Phosphine.

Results

The levels of infestation by E. cautella of stored” cacao during the course of this experiment were very low.

The evaluations were thus carried out for the control of beetles as a group and individually for T. castaneum, A. advena, Carpophilus spp. and C. ferrugineus since these insects were present in higher numbers. In addition, the effect of fumigation on the predatory anthocorid bug, B. sodalis was evaluated.

An analysis of variance made of the samples taken before fumigation showed no significant differences among the levels of beetle populations in the stacks (Table 21) . 93

After fumigation the results showed that there were no

significant differences in the levels of beetle populations

in the stacks treated for 4 8 hr, or for 72 hr.

The number of beetles were greater for untreated than for treated stacks. Population levels of living A.- advena,

T. castaneum, C. ferrugineus and the anthocorid bug, ,B. sodalis were significantly reduced when compared with the untreated stacks. However, there were no significant differences in population numbers of these insects in the treated stacks (Table 22). Only the dosage rate of 1 pellet/4 bags significantly reduced the numbers of

Carpophilus spp. in stacks treated for a 48 hr period.

However, stacks treated with all the dosage rates of phosphine for a 72 hr period had the numbers of this insect highly reduced.

Results on the percentage of control due to phosphine against all the beetles infesting the stacks are shown in

Table 23. The infestation level was roughly reduced by an average of 93.5% in stacks treated for 48 hr, and by an average of 94.5% for a 72 hr treatment period.

Discussion

The results of the evaluation of fumigation showed a significant reduction in the numbers of live insects in the bagged cacao beans (Tables 21 and 22). However, a few insects were still found alive after the period of exposure 94

Table 21. Means of transformed beetle counts following fumigation of cacao bags using phosphine. Ilheus, Bahia, March, 1979.1/

Treatments Before Fumigation After Fumigation

1 pellet/4- bags/ 2 / 12.64- 3.18 5 ab— 7 4 8 hr

1 pellet/5 bags/ 17.31 3.078 ab 48 hr

1 pellet/6 bags/ 2 0 . 06 5.364 a 48 hr

1 pellet/5 bags/ 19.12 4.242 ab 72 hr

1 pellet/ 6 bags/ 17 .56 2.689 b 72 hr

1 pellet/7 bags/ 13 . 50 2.738 ab 7 2 hr

Untreated (48 hr) 18.02 15.630 c

Untreated (72 hr) 14. 09 11.298 d

—^ Insect numbers transformed to / x + 1.

2 / — There was no statistical difference among treatments by F test.

3 / — Means followed by the same letter are not significantly different (p = 0.05). Duncan's multiple range test. Table 22. Means of transformed insect counts after fumigation of cacao bags using phosphine. Ilheus, Bahia, March, 19 7 9.5/

Treatments AA- 7 TC CF CS BS

1 pellet/4 bags/48 hr 2 . 821 a— 7 1. 095 a 1.137 a 1.563 a 1.165 a

1 pellet/5 bags/48 hr 2 .122 a 1. 069 a 1.095 a 2 .207 ab 1.104 a

1 pellet/6 bags/48 hr 4.359 a 1.491 a 1 . 000 a 2 .800 be 1.172 a

1 pellet/5 bags/72 hr 3. 820 a 1 . 061 a 1.130 a 1.295 a 1. 069 a

1 pellet/6 bags/72 hr 1.779 a 1. 095 a 1.104 a 1.563 a 1. 069 a

1 pellet/7 bags/72 hr 2 . 039 a 1. 564 a 1.034 a 1. 294 a 1. 034 a

Untreated (48 hr) 13.209 b 6.478 b 2 . 067 b 3. 046 be 3. 388 b

Untreated (72 hr) 7. 059 c 6 . 934 b 2.416 b 3. 381 c 1.591 c

— Insect numbers transformed to / x + 1.

—2 / AA = A. advena, TC = T. castaneum, CF = C. ferrugineus, CS = Carpophilus spp. , BS = B. soclalis. 3 / — Means followed by the same letter are not significantly different (p = 0.05). Duncan’s multiple range test.

CD cn 96

Table 23. Effect of fumigation of cacao bags using phosphine against Coleoptera. Ilheus, Bahia, March, 1979.

Insects before Insects after Percent Treatments fumigation fumigation control-

1 pellet/4 bags/48 hr 2324 129 92 .35

1 pellet/5 bags/48 hr 3827 115 95 . 85

1 pellet/6 bags/48 hr 6286 346 92 .41

1 pellet/5 bags/72 hr 5370 217 93 . 80

1 pellet/6 bags/72 hr 3513 92 95 . 98

1 pellet/7 bags/72 hr 2270 90 93 . 92

Untreated (48 hr) 4448 3227 -

Untreated (72 hr) 2827 1844

—^ Calculated by using the Henderson and Tilton (195 5) formula. to the fumigant, mainly Carpophilus spp. (Table 22)’. The time of exposure of the insect to a determined concentra­ tion of the fumigant depends on such factors as temperature, humidity, kind of produce, and the insect species. However, temperature is the most important factor. The gas efficiency increases with increased temperature, and less time is required for the fumigation when the same concen­ tration is used. A 4-8 hr exposure is recommended for fumigation with Phostoxin only when temperatures inside the warehouses are above 2 0°C. In the warehouses located in

Ilheus, temperatures are in general above 2 0°C. In this experiment temperature seems not to have had any influence on the effectiveness of fumigation. On the other hand,

Carpophilus spp. seems to be the most tolerant group of insects in this experiment, since only the higher dosage of phosphine for .48 hr gave good control of these beetles

(Table 22). Therefore, a greater exposure time is required for a higher effectiveness against these insects when using lower dosages. (R ) The placement of the Phostoxin pellets at the bottom of the stacks was probably another factor influencing the effectiveness of fumigation. Although the phosphine has a great diffusion power in all directions, it is heavier than the air, thus its concentration was probably lower at the top of the stacks where the bags were sampled for insect assessment.

The data obtained in this experiment showed that fumigation of bagged cacao beans using phosphine is an effective method of insect control (Table 23) , considering that evaluation was on top of stacks, and pellets were distributed at the bottom. GENERAL DISCUSSION

On the basis of the results obtained in the present study some recommendations can be made in order to reduce insect infestation in stored-cacao in Bahia.

The assessment of infestation using a sloping sieve of 5 mm mesh, and collecting the insects mixed with debris plus fragmented cacao beans in a small fabric bag is the method recommended for future surveys at the grower’s estates, and in the warehouses located at the marketing centers.

The food traps were also efficient in surveying and

1 monitoring stored-cacao insects. However, this method is only recommended for research programs. It requires more trained personnel, materials, and rooms with controlled temperature and relative humidity.

The suction light traps fitted with the BL fluores­ cent lamp are recommended to detect or monitor insect in­ festation in the warehouses located at the port, in the warehouses located in the marketing centers, and in the warehouses of the chocolate factories. They should be placed above the stacks. The baiting of these traps with one fiber filled with sex pheromone would increase the

99 100 catches of the almond moth, E. cautella. However, it is not yet recommended considering the problems involving the acquisition and importation of such product.

Besides detecting and monitoring the insects, suction light traps are also a useful tool in reducing insect populations in warehouses, therefore, reducing contamina­ tion by the fragments that become mixed with the cacao beans.

The spraying of cacao stacks- with pirimiphos-methyl 2 is recommended at a dosage rate of 5 00 mg ai/m for the protection of bagged cacao against attack by insects. It is recommended not only to spray cacao stored in the ware­ houses located in Ilheus and in the other marketing centers , but also in the grower's premises if cacao is retained for extended periods. This insecticide is safe and proved to be effective against stored-cacao insects. However, before an effective recommendation, it will be necessary to deter­ mine the residues and the rate of disappearance of the insecticide in the cacao beans. This insecticide, although used in several countries to control stored-grain insects, is not yet registered in the U.S., and probably the toler­ ance level of residue for cacao beans is not yet established.

The economic injury levels for the insect pests of stored-cacao are not yet suggested, because of lack of data on the population densities that causes economic damage. It will be advantageous to determine these 101

densities in order to treat stored-cacao only when necessary.

The fumigation of cacao before shipment at the port of

Ilheus is already underway with Phostoxin at a dosage rate of 1 pellet/5 bags for 72 hr. However, the efficacy of fumigation can be improved by placing half of the pellets on the top of stacks. In addition, by increasing the dosage rate to 1 pellet/4 bags the time of exposure can be reduced to 48 hr without reducing efficiency. T

CONCLUSIONS

Experiment 1 - Survey by Means of Sieving.

1. The major insect pests associated with stored-

cacao in Bahia are Ephestia cautella, Ahasverus

advena, Carpophilus dimidiatus, Tribolium castaneum

and Lasioderma serricorne.

2. Higher levels of infestation of bagged cacao

occurred at the end than at the beginning of the

crop season.

3. The wasp, Bracon hebetor which parasitizes the

larvae of E. cautella creates problems since it

may increase the quantity of insect fragments in

infested.cacao beans.

4. The anthocorid bugs, Buchananiella sodalis and

Xylocoris afer are the main predaceous insects

found associated with cacao.

Experiment 2 - Monitoring for Insect Pests in a Cacao

Warehouse using Food Traps.

1. The data obtained in the survey using food traps

indicate that insect populations in the warehouses

are low at the beginning of the crop season and

102 103

high by the end of the crop season.

2. The cleaning, painting, and spraying the warehouses

is of immediate benefit in reducing the residual

infestation from the previous crop season.

Experiment 3 - Comparison of Fluorescent Lamps with

Different VJavelengths Operated Simultaneously

1. In general, the beetles showed a preference for the

BL lamp.

2. The parasitic wasp, B. hebetor showed the same

preference for the BL and BLB lamps.

3. E. cautella showed the same preference for the BL

and G lamps.

*4. The predatory anthocorid bug, B. sodalis prefers a

waveband ranging from the ultraviolet through the

blue portion of the spectrum.

Experiment *4 - Comparison of Fluorescent Lamps with

Different Wavelengths Operated Independently

1. When the lamps were operated independently, E.

cautella, B. hebetor, L. serricorne and Bethylid

wasps were attracted equally to all fluorescent

lamps.

2. The sap beetle, Carpophilus ob'soletus unquestionably

prefers the BL and BLB lamps. 104

(R) 3. The Ellisco light trap seems not to be effective

in capturing E. cautella in warehouse conditions.

4. Light traps can be an useful tool in reducing B.

hebetor populations in cacao warehouses, therefore

reducing contamination by the fragments that be­

come mixed with the cacao beans.

Experiment 5 - Influence of Lamp Wattage on the Catches of

Insects Associated with Stored-Cacao.

1. The number of L. serricorne and A. advena increased

in almost direct proportion to the BL lamp size.

2. The increase in wattage results in 3 times more E.

cautella, B. hebetor and bethylid wasps being

captured in the traps with the BL lamps.

3. The increase in wattage results in 9 times more C.

obsoletus and X. afer being captured in the traps

with the BL lamp.

Experiment 6 - Fluorescent Lamps and Sex Pheromone Influence

on Suction Trap Catches of E. cautella■

1. Suction traps baited with the sex pheromone are

more effective for capturing the adult of E.

cautella in cacao warehouses than unbaited suction

traps.

2. Suction traps with the BL and G fluorescent lamps

are more effective than traps without the lamps. 105

3. The suction traps baited with the sex pheromone

are more desirable to suction traps fitted with

either the BL or G lamps for detection and moni­

toring E. cautella.

*4. Suction traps with either the BL or G lamps are

more effective in capturing L. serricorne than the

suction traps without lamps.

5. Suction traps fitted with the BL lamps are more

effective in collecting the anthocorid bug, X.

afer.

Experiment 7 - Effect of the Sex Pheromone Release Rates on

E. cautella Catches.

1. The release rates of the sex pheromone used in

cacao stores in Bahia were equally effective in

catching E. cautella.

2 . Traps with virgin females were more effective than

traps baited with the sex phereomone.

3. The sex pheromone trap can be a valuable tool for

the detection of infestation with E. cautella in

cacao stores. Besides, it can be very useful in

the monitoring of E. cautella populations. 106

Experiment 8 - Effect of Height on the Sex Pheromone Trap

Catches.

1. The greatest catches of E. cautella occurred

high in the cacao warehouse, above stack level.

Experiment 9 - Evaluation of Insecticide Sprays for the

Protection of Bagged Cacao.

1. Chlorpyrifos-methyl, pirimiphos-methyl, permethrin

and fenitrothion sprayed on the bags were

effective for the protection of bagged cacao

beans.

2. Bags treated with chlorpyrifos-methyl, pirimiphos-

methyl and permethrin were less infested than

the bags treated with fenitrothion.

3. .Permethrin was the most effective insecticide for

the protection of bagged cacao beans against

attack by L. serricorne.

*+. The spraying of bags at intervals of 2 months

with chlorpyrifos-methyl, pirimiphos-methyl and

permethrin after an initial fumigation with

phosphine gave good protection of the cacao beans

for at least 10 months. 107

Experiment 10 - Evaluation of Fumigation on Insect Pests

in Bagged Cacao Beans using Phosphine.

1. All the dosages of phosphine used in the experi­

ment were effective in controlling the populations

of beetles associated with stored-cacao. However,

this efficiency can be improved by placing half

of pellets on top of stacks.

2. The dosage of 1 pellet/4 bags for 48 hr exposure

as well as all the dosages for 7 2 hr exposure were

effective in controlling Carpophilus spp.

3. The anthocorid bug, Buchananiella sodalis was

also controlled by all the dosages used in the

experiment.

4. The time of exposure can be reduced to 4 8 hr if

the higher dosage (1 pellet/4 bags) is used, with­

out reducing the efficiency of treatments.

5. Dosages lower than 1 pellet/5 bags can be used if

the time of exposure is maintained for 72 hr. SUMMARY

A survey was conducted to determine the major stored- pests and the degree to which they infest cacao exported from Bahia. In addition to food traps and sieving, light traps, suction traps and pheromone traps were used to detect or monitor pest populations. Finally, an evaluation was made of insecticides for the protection of bagged cacao from insects.

A total of 26 84 bags of cacao were sampled at the port of Ilheus for insect infestations. Results of this survey showed that Ephestia cautella, Ahasverus advena,

Carpophilus dimidiatus, Tribolium castaneum and Lasioderma serricorne were the major insect pests associated with stored-cacao in Bahia. However, not only detrimental insects were captured, parasites of various grain pests were also captured. Found in the samples were: Bracon hebetor, Anisopteromalus calandrae, Plastanoxus laevis and Holepyris, sp. The anthocorid bugs, Buchananiella sodalis and Xylocoris afer are the main predaceous insects found in the samples. 109

The results of the food traps survey indicate that

insect populations in the warehouses were low at the

beginning of the crop season and high by the end of the

crop season.

In general, the beetles are most attracted to light

traps fitted with the BL lamp. The parasitic wasp, B.

hebetor and the sap beetle, Carpophilus obsoletus, showed

equal preference for the BL and BLB lamps, whereas E .

cautella showed equal preference for the BL and G lamps.

The number of insects captured in the light traps increased

as the wattage was increased in the BL lamps.

Suction traps baited with the sex pheromone (Z)— 9 ,

(E)-12-tetradecadienyl acetate collected higher numbers of

E. cautella than unbaited suction traps.

Different release rates of the sex pheromone used in cacao stores in Bahia were equally effective in catching

E . cautella.

It was shown that the greatest catches of E. cautella occurred high in the cacao warehouse above stack level.

The insecticides pirimiphos-methyl, chlorpyrifos- methyl and permethrin were the most effective insecticides for the protection of bagged cacao against attack by insects.

All the dosage rates of phosphine, used in the evaluation of fumigation on bagged cacao, were effective in controlling beetle populations associated with stored- cacao in Bahia. However, Carpophilus spp. were the most difficult group of beetles to control in this experiment.

Efficient control of Carpophilus spp. was achieved only with the dosage rate of 1 pellet/4 bags for 48 hr of exposure, or with longer exposure (72 hr) at any of the t rates. BIBLIOGRAPHY

Bondar, G. 1938. Estragos em cacau no transporte comercial. 0 campo (Brazil) 98 (9):65.

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