LABORATORY OBSERVATIONS ON THE LIFE HISTORY AND PREDATORY EFFICIENCY OF SEVEN SPECIES OF PHILONTHUS (COLEOPTERA: STAPHYLINIDAE) ON THE HOUSE FLY (DIPTERA: MUSCIDAE).

CHANI POSSE, M. R.

Foz de Iguazú, Brasil

Congreso; XXI INTERNATIONAL CONGRESS OF ENTOMOLOGY (XXIICE); 2000

Sociedade Entomologica de Brasil - Embrapa

The Southamerican dung-beetle fauna includes many predatory and parasitic species belonging to the families Staphylinidae, Hydrophilidae and Histeridae (Fletchmann 1995; Cabrera Walsh et al. 1997; Guimaraes et al. 1998). Beetles from these three families have been shown to reduce populations of dung-breeding flies in both southern Africa (Fay 1980; Doube et al. 1987; Doube 1987) and North America (Roth 1982; Summmerlin et al. 1982; Fincher 1994; Hu et al. 1996; Hu et al. 1997). Staphylinids of the genus Philonthus have long been important predators of dung-breeding Diptera. However, the bionomics of local Philonthus species are virtually unknown. The present study constitutes a preliminary investigation about biological aspects of local Philonthus species and their ability to prey on dung-breeding flies under laboratory conditions. Seven species of Philonthus which are frequent inhabitants of cattle dung in Tucuman, Argentina, are considered for study. Potential predators were collected from naturally deposited dung by collecting the excrement in the field, returning the manure to the lab and removing the insects by flotation. Rearing techniques was developed by following the method of Hunter et al. (1986) for Philonthus. For observation, individual beetles from egg to adult were confined and house fly eggs and 1st instar larvae were provided for food. Data on egg hatch, larval molt, pupation and adult emergence, as well as counts of house fly eggs and larvae offered and consumed were recorded daily. Variables considered in data analysis were feeding rates of Philonthus larvae and adults as well as duration and size of each stage from egg to adult. Results derived from a cluster analysis showed that Philonthus rectangulus, P. bruchi and P. sp7 comprised a cluster associated primarily with the highest feeding rates and sizes. The other cluster comprised P. flavolimbatus, P.sp5 and P.sp6. These species were smaller and had lower feeding rates. P. pauxillus appeared as a separate taxa with the lowest feeding rates. Duration of life cycle from egg to adults are reported for all species. Based on these preliminary results, we conclude that Philonthus rectangulus, P. bruchi and P. sp7 appear to be prospective biological control agents of dung-breeding flies although additional field and laboratory investigations are required to accurately access their effectiveness. Index terms: Philonthus rectangulus, P. bruchi, feeding rates, potential predators, house fly.