Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 2005
Publication Date: November 1, 2005
Citation: Geden, C.J. 2005. Biological control of arthropod pests in livestock production. Meeting Abstract. Flakkebjerg, Denmark. Nov. 1-3, 2005. Technical Abstract: Filth flies and poultry litter beetles have a wide array of natural enemies that can be exploited for augmentative biological control. Adult flies are subject to infection with entomogenous nematodes and the fungal pathogens Entomophthora muscae and Beauveria bassiana. Of these, B. bassiana has the greatest potential for operational fly control because it is economical to produce, has a long shelf life and can be deployed in a variety of ways. A baculovirus (SGHV) was discovered recently that may hold promise as well; the virus causes hyperplasia of the salivary glands and appears to shut down ovarian production. There are several important predators of fly eggs and larvae, including the mite Macrocheles muscaedomesticae, the histerid beetle Carcinops pumilio, and the black dump fly Hydrotaea aenescens. Mass rearing methods have been developed for these predators, and C. pumilio and H. aenescens are now available as products from commercial insectaries. The most widely used natural enemies are pteromalid pupal parasitoids in the genera Muscidifurax and Spalangia. Muscidifurax species tend to forage for pupae near the manure surface and have short development times whereas Spalangia species forage deeper in the substrate and have longer development times. Rearing methods for these parasitoids are straightforward but require close attention to detail and the biology of the species being produced. The first requirement is an efficient method for mass-rearing hosts; house flies can be grown for $0.50 per 10,000 fly pupae. Pupae are exposed to hosts for about 3 days, using host:parasitoid ratios that ensure high rates of parasitism without causing excessive mortality because of superparasitism. Rearing protocols also need to take into account whether the species is solitary or gregarious and the aggressiveness of parasitoid larvae in superparasitized hosts. Parasitoid releases have been demonstrated to be an effective fly management tool in several studies, including tests in Denmark, New York, Maryland, Nebraska, and Florida. Most filth fly parasitoids are vulnerable to Nosema disease that can cause a 90% reduction in wasp fecundity. The disease is very common in mass-reared pteromalid colonies, where transmission is amplified by horizontal transmission within superparasitized hosts and the high efficiency of maternal transmission. Infection can be prevented by careful screening at the time of colony founding and can be controlled by drug and heat therapy.