TOXICITY OF SELECTED INSECTICIDES TO DIURAPHIS-NOXIA (HOMOPTERA, APHIDIDAE) AND ITS NATURAL ENEMIES

Laboratory bioassays were done to identify insecticides with different ial toxicity to Russian wheat aphid, Diuraphis noxia (Kurdjumov), and associated parasites and predators. Fourteen insecticides were tested against adults of 3 species of parasites and against 3rd instars of 4 species of coccinellids. The insects were exposed to insecticide resid ues on inner surfaces of 20-ml glass vials. Ten insecticides were test ed for contact and systemic toxicity against D. noxia adults. Among te sted aphicides, acephate was the least toxic to both the parasites and the predators and showed a relatively high systemic toxicity to D. no xia. In contrast, malathion was highly toxic to both the parasites and predators and showed low toxicity to D. noxia. The selective toxicity of acephate to D. noxia suggests that this insecticide could be impor tant for use in programs to manage D. noxia. The high selectivity of m alathion against natural enemies suggests that this insecticide could be valuable in insecticidal check studies for investigating natural en emy efficacy.