Heat adaptation of the house fly (Diptera: Muscidae) and its associated parasitoids in Israel

Authors: BIALE, HAIM - US Department Of Agriculture (USDA); Geden, Christopher - Chris; CHIEL, ELAD - University Of Haifa

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2019
Publication Date: 10/2/2019
Citation: Biale, H., Geden, C.J., Chiel, E. 2019. Heat adaptation of the house fly (Diptera: Muscidae) and its associated parasitoids in Israel. Journal of Medical Entomology. 57(1):113-121. https://doi.org/10.1093/jme/tjz152.
DOI: https://doi.org/10.1093/jme/tjz152

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 Israel. Israeli flies were tolerant of hot conditions but their parasitoids had shorter lives and produced fewer progeny Israeli populations of both the flies and the parasitoids were more tolerant of hot conditions than US populations were. The results suggest that evaluations of parasitoids from historically hot locations could lead to the discovery of heat-adapted strains that could for fly control during under hot conditions.

Technical Abstract: nsects are ectothermic organisms, hence all aspects of their biology are strongly influenced by ambient temperatures. Different insect species respond differently with phenotypic plasticity and/or genetic adaptation to changing temperatures. Here we tested the thermal adaptation of the house fly and three of its parasitoids species by comparing life-history parameters in populations from a hot climate region (Jordan valley) and populations from a moderate climate region (Galilee). No significant differences were found between the two house fly populations, both under hot and moderate experimental conditions. Life-history parameters of the parasitoids (Muscidifurax raptor Girault & Sanders, Spalangia endius Walker, and S. cameroni Perkins) varied markedly between origins, species, sexes and experimental conditions. Of the three species tested, only Muscidifurax raptor collected in the Jordan valley proved better adapted to experimental heat conditions, compared to its counterpart population that was collected in the Galilee. Additionally, we tested the effect of elevating temperatures on a house fly lab population for 17 consecutive generations and found no evidence for heat-adaptation. We discuss our results in the context of house fly control and global warming.