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Home , Ascidae, Blattisocius, Blattisocius tarsalis, Mediterranean flour moth

Proceedzngs of the 7th Intertuuional Workzng Conference on Stored-product Protection - Volume 2

The use of tarsalis (: ) for biological control in mills

Abstract recorded from a number of regions (Chant, 1963; Hames, 1984) B. tarsalis IS pnmanly found m connection WIth The Mediterranean flour Ephest~a kuehnuella Zeller stored food matenals and often mfests laboratory cultures of (Lep. : Pyrahdae) ISone of the mam species m Danish Ephestui spp. and Triboliurn. spp. (Hughes, 1976). A flour mills As methyl brorrude was prohibited m Denmark detailed study by Hames (1981) on the biology of B. from 1 January 1998, the nulls are forced to rely on a tarsalzs at 2TC 173% r. h. demonstrated that this species combmation of other chemicals or alternative control displayed a strong preference for moth eggs when offered methods, mcludmg IPM and m the future probably biological eggs of E. cautella and Tribouum. castaneum (Herbst), control as well. Blatnsocius tarsaus (Berlese ) (Acari: further that B tarsalzs can develop on alternative prey Ascidae) , a predatory on moth eggs, has shown species e. g. eggs of Tribolium species. He also found that charactenstics, which make It SUItablefor biologicalcontrol. under the actual expenmental conditions the potential rate of In this study the consumption rate of B. tarsalzs on mcrease of B. tarsalis far exceeded that of E cautella different age groups of E. kuehniella eggs was ThIS study was carried out pnncipally to mvestigate how investigated. Eggs aged 0 - 1, 1 - 2, 2 - 3, and 3 - 4 days B tarsalis responded to different age groups of E were tested at 21°C, 75% r h. There were no differences kuehniella eggs and to test whether young eggs are between the numbers destroyed (p > 0 .05 ), but a larger preferred to old. amount of the oldest eggs was consumed compared to eggs 0 -1 days old (p<0.05) Materials and Methods

Origin of the mite The were cultured m plastic cups (280 ml, 095 Introduction mm) With a 40mm perforation m the hds covered With filter paper. ThIS filter paper was carefully fastened WItha water- The Mediterranean flour moth (Ephestza kuehruelui Zeller based glue m order to create a mite-tight seal New cultures (Lep : ) ) ISa senous pest m the nullmg mdustry, were started WIth 2g of Vermlculite® , 0.15g of E. and most mills m Scandmavia are fumigated once or twice a kuehniella eggs, wluch have been killed by freezmg, and year WIth methyl bromide. However, methyl bromide was 10 large B. tarealis , probably all adult females. The prohibited m Denmark from 1 January 1998 forcmg mills to cultures were placed m a plastic box WItha relative humidity rely on a combmation of other chemicals or alternative of 75%, usmg saturated aqueous solutions of NaCl methods. ThIS, together With the consumers' demand for (Greenspan, 1977) The boxes were placed in a regulated, food free of residues, could encourage the use of environmental chamber at 25 ± 2°C m complete darkness. bIOlogIcalcontrol methods m mIlls. Mter 3 weeks the cultures usually contamed large numbers Due to the prohIbItion of methyl bromIde m Denmark of mItes, whIch were supphed each week WIth 0.05g moth many efforts are bemg allocated mto research on relevant eggs to mamtam the population at that level natural enemIes of E. kuehnwlla (Hansen, m press) Only adult female mItes were used in thIS study. They NIelsen (m press) argued that the predatory mIte were recogmzed by theIr SIze and oval shape, but (Berlese) could be a speCIesuseful for addItionally the form and SIze of the ventrianal shIeld were bIOlogIcalcontrol of E. kuehniella m Scandmavmn flour checked under magmficatIon after the expenments to mIlls B. tarsal~ ISa common predator on moth eggs, and confIrm the IdentifIcation of stage (Haines, 1979). No It seems to be cosmopohtan in dIstnbutIon, havmg been attempt was made to determme theIr age nor to synchromze.

1Darush Pest Infestation Laboratory, Mmlstry of Food, Agnculture The experiment methods and Flshenes,Skovbrynet 14, DK-2800 Lyngby, Denmark In order to examme the dally food consumption rate m 1265 Proceedings of the 7 th International Working Conference on Stored-product Protect ian - Volume 2 relation to the age of the eggs, adult female mites were The same picture was observed when the observations were given three fresh E. kuehniella eggs for 24 hours at a recorded as mean number of destroyed or completely temperature of 21°C and 75 % r. h.. The experiments were deflated eggs. Inside the experiment a similar amount of conducted in regulated, environmental chambers with a eggs were consumed and destroyed when the two age groups temperature tolerance of ± o. 50C and in complete darkness. were compared, but a larger number of the old eggs was Eggs aged 0-1, 1- 2, 2 - 3, and 3 - 4 days were used in completely deflated. the experiments. In order to obtain the different age 3,------, groups, isolated 0 - 1 day old eggs were placed at 25"C for the mentioned periods. The experimental units consisted of 2.5 small plastic cups 02.5 ml , 025 mm) in which a piece of filter paper with the eggs was placed on the bottom, At the .:l" 2 top the units were sealed with filter paper and a lid with a 12 ~ -" mm hole. This unit had an inside area of 31cm'. After the • 1.5 observations the number of completely or partially deflated ..•'" eggs was counted. Beside the number of destroyed eggs, the g amount of food consumed was also expressed in whole-egg ·$ equivalent, where the partially deflated eggs were assigned " 0.5 a value of 25%, 50%, and 75% according to the degree of deflation. The experiments were replicated 30 times, and eggs, which had not been exposed to mites served as controls in each experiment. To test whether young eggs Age groups in days were preferred to old eggs female mites were offered 10 Fig. 1. -Mean number of kuehniella.-eggs destroyed eggs for 24 hours, 5 of which were young (0 - 1 day) and 5 by adult female Blattisocius tarsalis during 24 hours old (2 - 3 days). The number of deflated eggs in both age at 21 'C in relation to different age groups of the groups was recorded and compared with each other, and the eggs. Grey bars: Mean number of completely result was also compared with an experiment where female deflated eggs. Black bars: Mean total number of mites were offered 10 eggs (0 - lday old) for 24 hours. All destroyed eggs. Means with the same letter within other relations are as above. The data were transformed the two kind of observations are not significantly with (log x + 1) and analyzed by GLM (general linear different (p>0.05). model) procedures, and the difference between the means were analyzed by a Waller-Duncan test (SAS, 1995). The significance level was in all cases a~ 0.05. 2.5,------, Results

Only very few eggs in the controls collapsed. Of a total of 300 eggs used in the control series, only 8 eggs collapsed ~· 1,5 ~ (all partially) during the 24 hours. No attempt was made in s e- order to correct for this low control mortality. With a prey · density of 3 eggs the same number of eggs was destroyed fo independent of the age (Fig. I), although significantly more. .. ~ 0.5 eggs were completely deflated in trials with old eggs (2 - 3 ~ and 3- 4 days) compared to young eggs (0 - 1 day). The difference between the grey and the black bars in fig. 1 is 0-1 1-2 2-3 3-4 the number of partially destroyed eggs. Age groups ill days The calculated mean number of whole-egg equivalents consumed by mites when offered old eggs (3 - 4 days) was Fig. 2. Mean number of whole-egg equivalents (see text) of larger than the amount consumed when offered young eggs Ephestia huehniella-esgs consumed by adult female (0-1 day) (Fig. 2). Blattisocius tarsalis during 24 hours at 210C in When the mites were offered a choice between young and relation to different age groups of the eggs. Means old eggs (Table 1), a larger number of whole-egg with the same letter are not significantly different equivalents were consumed compared with an experiment, (p>005). where the mites were only offered young eggs (0 - 1 day). 1266 Proceedmqs of the 7 th International Working Conference on Stored-product Protection - Volume 2

Table 1. Mean number ( ± s. d. ) of Ephestu: kuehnwlla-eggs destroyed by adult female Buutisocius tarsalis dunng 24 hours at 21"C. In A, the mites were offered 10 young eggs and in B 5 young and 5 old eggs. Means between A and B (total) With the same letter are not sigmficantly different (p > 0.05). Means withm B (divided) with the same letter are not significantly different (p >0 05). A B(total) Bf drvidcd) Age of eggs m days 0-1 0-1+2-3 0-1 2-3 Mean no. of whole-egg equivalents consumed 1.8 ± 1.3a 2.3 ± 0.7b 1.1 ± 0.8a 1.3 ± LOa Mean no. of eggs destroyed 3.3 ± 2Aa 4.0 ± 1.5b 2.1 ± 1.5a 1.9 ± 1.4a Mean no. of eggs completely deflated 0.27 ± OA5a 0.87 ± 0.57b 0.20 ± OAP 0.67 ± 0.67b

development. Discussion Acknowledgements The predatory rrute B. tareaue IS considered a pronusing candidate for biological control of E kuehniella m flour ThIS study was financially supported by the program mills, since It IS active at temperatures relevant for the 'Biological and microbiological control of pests (1996 - SItuation m Damsh flour nulls in the spnng (NIelsen, 2000)' from the Danish Ministry of Food, Agriculture and 1997) Other studies have focused on this mite. Graham Fishenes Thanks to technician, Ulrik Cold, for hIS (1970) reported on the regulatory effect of B. tarsalis, assistance m the practical work. which was regarded as the major suppressive factor in controlhng an infestation of Epheetui (Cadra) cautella References (Walker) m a warehouse in Kenya Hames (1981) found that the potential rate of increase of B. tarealis far Chant, D. A 1963. The subfamily Blattisocinae Garman exceeded that of E cautella at 27°C. (Aceosejmae Evans) (Acarina: Blattisocidae Garman) As E kuehniella eggs exist for some time (e. g 5 days (Aceosejidae Baker and Wharton) m , with at 25°C), during this time changmg composition in both descriptions of new species Canadian Journal of Zoology. content and in the chorion, it was found relevant to 41, 243 - 305 investigate whether B. tarsalis would attack eggs Graham, W. M. 1970. Warehouse ecology studies of bagged independent of the age of the eggs and whether It would maize m Kenya-II Ecological observations of an mfestation prefer young eggs to old ones. It has been reported (White by Ephestui (Cadra) cautella (Walker) (, & Huffaker, 1969) that E kuehmiella eggs become less Phycitidae). Journal of stored products Research. 6, 157 favoured by B. tarsalie towards hatchmg. In the present -167. study B. tarsalis was offered eggs With a specific age and Greenspan, L. 1977 Humidity fixed points of binary the number of eggs destroyed during 24 hours was not saturated aqueous solutions. J. Res. Nat. Bur. Stand. - dependent upon the age of the eggs. The mites utilized the A. Phys, and Chem.. 81A(1), 89 - 96. old eggs m another way compared to young eggs as more old Hames, C. P. 1979. A revision of the Blattisocius eggs were completely deflated. ThIS could be a consequence Keegan ( : Ascidae) with special reference to of older eggs being nutritionally mfenor to young ones, B. tarsalis (Berlese) and the description of a new which the rrutes compensate for by consuming a larger species. Acarologia. 20,19 - 38. amount of each single egg. When the mites were given the Hames, C. P. 1981. Laboratory studies on the role of an egg choice between young and old eggs the only difference predator, Btattieocius iarealis (Berlese) (Acan: between the two kinds of prey was again that a larger Ascidae) , in relation to the natural control of Epheetui number of the old eggs where completely deflated cautella (Walker) (lepIdoptera, Pyrahdae ) in The present study has demonstrated that B. tarsalw is warehouses. Bulletin of Entomological Research. 71, 555 potentially useful for biologIcal control of E kuehnwlla , -574 smce females destroy large amounts of prey mdependent of Haines, C. P. 1984 Biological methods for integrated the age of the eggs. A large number of eggs are only control of msects and mItes in tropIcal stored products. partially deflated, but none of these eggs will hatch. It is III: The use of predators and paraSItes. Tropical Stored possible to start a mass-production of thIS mIte, as eggs of Products Information, 48, 17- 25. E. kuehniella are commercially available and Hames Hansen, L. Stengaard. (In press). Prospects for developmg (1981) found that chIlled moth eggs are SUitable food for strategies for bIOlogIcalcontrol of the Mediterranean flour 1267 Proceedinqs of the 7th Iuternatumal Working Conference on Stored-product Protection - Volurne 2

moth Ephestw kuehiuetla m flour nulls IOBCIWPRS Scandmavian flour mills? IOBCIWPRS Bulletm. SAS, Bulletin 1995 SAS Version 6. 11 SAS Institute Inc 1989 - 95. Hughes, A. M 1976. The mites of stored food and houses Cary, N. C. USA MAFF Techmcal Bulletm 9. HMSO London 400pp. White, E. G and Huffaker, C. B 1969. Regulatory Nielsen, P. S 1997. in organically produced processes and population cyclicity m laboratory populations cereals In: Damsh Pest Infestation Laboratory Annual of Anagasta kusi U!lla (Zeller) (Lepidoptera: Phyci tidae) . Report 1996 pp, 70 - 71. I. Competition for food and predation Res. Pop. Eco 11 Nielsen, P. S. (In press). Blatusocuis tarsaiis (Berlese); (1), 57 - 83 would this predatory mite be effective against moth eggs in

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