Effect of Avermectin on embryonic and postembryonic development of Argas (Persicargas) arboreus (Acari: Argasidae)

Abstract

Topical application of a single dose (10µl/tick or egg batch) of different concentrations of Abamectin (an avermectin) has lethal and biological effects on the engorged mated adult female, immatures and egg of Argas (Persicargas) arboreus that induced 100% mortality at 25,15 and 10 ppm, respectively. Abamectin treatment at lower concentrations of 1-10 ppm interfered with the female reproduction, nymphal and egg development. Abamectin topical (3-10 ppm) application on mated engorged adult female A. (P.) arboreus at different intervals of its reproductive cycle reduced fecundity and fertility of the female, prolonged its preoviposition, oviposition and the egg incubation periods. The effects were most prominent during vitellogenesis and the least at the start of oviposition. Abamectin treatment of the newly moulted fed 2nd nymphal instar, delayed its moulting and of the resulted 3rd instar and reduced adult emergence. The treatment caused paralysis and various deformities (15.6- 28.6%) as missing legs at the coxal level, changes in colour and failure to moult or to detach the old exuvia in the resulted 3rd nymphal instar.