SUBLETHAL EFFECTS OF TEFLUTHRIN ON DIABROTICA-UNDECIMPUNCTATA-HOWARDI, BARBER - PLANT-PROTECTION AND LARVAL DEVELOPMENT

Larval stages of the southern corn rootworm, Diabrotica undecimpunctat a howardi (Barber) (Coleoptera: Chrysomelidae), were used to assess th e effects of sub-lethal concentrations of the soil insecticides teflut hrin and terbufos. It was shown that significant plant protection was only possible with high (LC80) levers of terbufos, whilst protection w as achieved with much lower (LC20) concentrations of tefluthrin. This protection was achieved by anorectic, poisoning effects of the pestici des on the larvae. Unlike tefluthrin, terbufos did not affect feeding activity at sub-lethal levels and a high level of pest mortality was r equired for comparable protection. The reduced feeding of the tefluthr in-treated larvae also led to lower larval and adult weights and lower survival to adulthood when compared with controls. (C) 1997 Elsevier Science Ltd.