Effects of ingestion of dung containing ivermectin on aspects of behaviour in the fly Neomyia cornicina

Abstract. Adults of the dung fly Neomyia cornicina (Fabricius) were fed continuously on either dung containing no ivermectin (control dung) or dung containing 0.125 μg g^-1or 0.25 μ g^-1ivermectin (wet weight).Comparisons were made between the behaviour of flies during the first 24 h of dung feeding and that observed after 96 h of feeding.Subsequent experiments investigated the effects of ivermectin ingestion on three measures of locomotory ability: escape time, time to re-right, and capture time.
Analysis of behavioural data showed a significant reduction in the activity of ivermectin-fed flies compared to that of the controls.After 96 h of feeding on dung containing ivermectin, there was a significant increase in the duration of time spent standing and a reduction in duration and frequency of walking and grooming behaviours compared to controls.
Seventy-two hours after the onset of dung feeding, flies fed dung containing ivermectin took significantly longer to escape from a glass tube and to re-right themselves after overturning than flies fed control dung.The time taken to capture flies that had fed on dung containing ivermectin at 0.25 μg g^-1was significantly shorter than that required to catch control flies when flies from the different treatment groups were presented blind and randomly.