Influence of the Nematode, Heterotylenchus autumnalis1 , on the Behavior of Face Fly, Musca autumnalis2

Abstract

Face flies, Musca autumnalis (Diptera: Muscidae), of both sexes infected with the nematode, Heterotylenchus autumnalis (Tylenchida: Allantonematidae), visited the faces of cattle and fresh cattle dung. However, female flies greatly outnumbered males at both sources. Generally. infected male flies found on cattle and dung contained young nematodes. In contrast, infected females on cattle contained nematodes of all ages, and most infected females from dung contained older nematodes. The propensity of healthy female flies to visit faces of cattle and dung depended on their gonadotrophic age. The majority of flies with immature eggs were found on cattle while the majority with mature eggs were found on dung. Infected flies containing early nematode stages appeared to behave like healthy ones with immature eggs. However, once the nematodes invaded the flies' ovaries, the flies' behavior changed. These infected flies were found primarily on dung and apparently became “terminal” dung feeders.