A bait formulated with Metarhizium anisopliae for the control of Musca domestica L. (Dipt., Muscidae) assessed in large‐scale laboratory enclosures

The entomopathogenic fungus Metarhizium anisopliae was formulated into a bait for assessment against Musca domestica (housefly). Its efficacy was tested by placing either one, two or four baits on the floor of a 10 m3 polythene cubicle and releasing 100 female and 50 male M. domestica. One, two or four baits had equal effects and, between 95.2 and 100% of flies were killed after 10 days. In a second experiment, the durations of visits by single or pairs of flies to the baits and subsequent pick‐up of conidia were recorded. Single flies remained in the baits for up to 33 min and picked up a mean of 38 235 ± 8291 conidia. When pairs of flies were exposed, the individuals picked up a mean of 95 879 ± 23 838 conidia, which was significantly more (P < 0.05) than the single flies, although the mean duration of the visits was not significantly different (P > 0.05). However, the numbers of conidia picked up by the flies did not correlate with the duration of the visit. Lastly, 25 female and 25 male flies were exposed in 0.027 m3 arenas, to 10 M. anisopliae‐killed houseflies, showing sporulating hyphae. After 8 days, 97.3% of female flies and 100% of male houseflies had succumbed to infection with M. anisopliae. The implications of these observations are discussed.