SUBLETHAL EFFECTS OF AVERMECTIN AND MILBEMYCIN ON THE GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE)

Lymantria dispar larvae trated with either 5.0 ot 1.0 ppm abamectin or 100 or 500 ppm Milbemycin D had significantly reduced frass output and weight gain, indicating feeding cessation. All sublethal concentrations delayed molting by at least 1 d. Larvae treated with 10, 5.0 and 1.0 ppm of Milbemycin D had increased frass output and weight gain compared with controls; they also exhibited wandering. Avermectin at all concentrations and milbemycin at higher sublethal concentrations appeared to act as depressants. At lower concentrations, milbemycin acted as a stimulant. -from Authors