Effect of fluctuating high temperatures on house flies (Diptera: Muscidae) and their principal parasitoids (Muscidifurax spp. and Spalangia spp. [Hymenoptera: Pteromalidae]) from the United States

Authors: Geden, Christopher - Chris; BIALE, HAIM - U.S. DEPARTMENT OF AGRICULTURE (USDA); CHIEL, ELAD - UNIVERSITY OF HAIFA; JOHNSON, DANA

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2019
Publication Date: 6/14/2019
Citation: Geden, C.J., Biale, H., Chiel, E., Johnson, D.M. 2019. Effect of fluctuating high temperatures on house flies (Diptera: Muscidae) and their principal parasitoids (Muscidifurax spp. and Spalangia spp. [Hymenoptera: Pteromalidae]) from the United States. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjz080.
DOI: https://doi.org/10.1093/jme/tjz080

Interpretive Summary: House flies are among the most important pests of humans and animals and are notoriously difficult to control. Flies breed in animal manure, refuse, and in crop waste associated with vegetable and fruit production. Fly control today is increasingly conducted under very hot conditions because of changes in agricultural practices and climate, but most management strategies have been developed in regions with moderate temperature regimes. Hot temperatures could affect the balance between the fly and its natural enemies, especially parasitoids that kill the fly in the pupal stage. In this study, researchers at the USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology (Gainesville, FL) and the University of Haifa (Israel) compared the heat tolerance of fly and parasitoid populations from various locations in the U.S. Flies were better adapted to hot weather than most of their parasitoids, but one species (Muscidifurax zaraptor) was as heat-tolerant as the flies. Populations from different parts of the US varied in their heat tolerance. The results show that M. zaraptor is the most effective parasitoid for fly control under hot conditions and that further exploration could result in discovery of more populations that would be effective under these conditions.

Technical Abstract: Colonies of house flies (Musca domestica L.) and four species of parasitoids (Muscidifurax raptor Girault and Sanders, M. zaraptor Kogan & Legner, Spalangia cameroni Perkins and S. endius Walker) were established by making collections from dairy farms near Bell, Florida, Beatrice, Nebraska, Minneapolis, MN, and San Jacinto, CA. Colonies were assessed for heat tolerance by comparing life history parameters under either moderate and fluctuating hot temperatures (26.7-41.7oC). Colonies of M. raptor, S. cameroni and S. endius subjected to the hot regime produced about ¼ as many progeny as under moderate conditions. Colonies of M. zaraptor were more heat-tolerant and produced an average 46.9% as many progeny under the hot regime compared with moderate conditions. There was little evidence for higher heat tolerance in parasitoid populations from historically hot locations (California desert and Florida). Colonies of M. raptor and S. endius that had been in culture for 24 years were the least heat tolerant. House flies collected from the same locations varied little in longevity, fecundity, or egg-to-adult survival either under hot or moderate regimes. Flies reared under hot conditions laid about half as many eggs (89/female) and had about half the egg-adult survival rate (47.3%) under hot compared with moderate conditions, indicating that heat stress had less effect on flies than on all of the parasitoids except M. zaraptor. An attempt to select for heat tolerance in flies by subjecting them to incremental increases in rearing temperatures for 20 generations resulted in little change in tolerance among the selected flies.