Heat Adaptation of the House Fly (Diptera: Muscidae) and Its Associated Parasitoids in Israel

Abstract

Insects 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 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 Spalangia cameroni Perkins [Hymenoptera: Pteromalidae]) varied markedly between origins, species, sexes, and experimental conditions. Of the three species tested, only M. 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.

Keywords: Muscidifurax; Spalangia; Host–parasitoid interaction.