Effects of ingested ivermectin on body mass

Abstract

Abstract. Adults of Neomyia cornicina (F.) given continuous access to cow dung containing ivermectin at concentrations of 0.5.0.25 and 0.125 μg g ‐1 , the range found in the dung of injected cattle (Sommer et al. , 1992), were monitored every 12 h for changes in mass and excretory rates over a period of 3–5 days. Compared with the control insects, adult females that had ingested ivermectin showed disrupted patterns of daily mass change, an increase in dawn mass, and greatly reduced rates of excretion. Flies fed continuously with dung containing ivermectin at 0.25 μg g ‐1 and 0.125 μg g ‐1 in a regime identical to the above showed significantly increased abdominal mass compared with the controls. The observations are discussed in relation to other known effects of ivermectin on insect physiology.