In vitro effects of ivermectin on adult and developmental stages of two species of blood feeding arthropods

Abstract

The efficacy of the parasiticide, ivermectin, at different concentrations, on adult and the developmental stages of the hard tick, Boophilus annulatus, and the head louse, Pediculus humanus capitis, was studied in vitro. Mortality, hatchability and egg morphology were included. The results indicated that the control adult lice were alive at 1200±2.5 min and no lice survived over 5 min at 50 ng/ml or higher concentration of ivermectin. Control adult ticks were alive at 57600±1008 min while at 100ng/m1, they survived for only 132±7.8 min. The hatchability of control eggs was 93% and 91% while, at 100 ng/ml of ivermectin it was 1.3% and 7.3% for head lice and ticks, respectively. Using light microscopy, the treated lice nits showed detachment and shrinkage of the embryos inside decolourized operculated shells when treated with ivermectin at 100 ng/ml. While, the treated tick eggs appeared dark with disfigured embryos and detached envelopes. Disfigurement increased with higher ivermectin concentration. On scanning electron micrographs, the treated lice nits were shriveled, disfigured or indented with the presence of operculum. While, the treated tick egg surface appeared nearly smooth or the shell was completely disfigured.