Toxicity baselines and efficacy of selected aphicides against turnip aphid(Homoptera : Aphididae) on cabbage

Toxicity baselines and efficacies of pirimicarb (Pirimor(R)), imidacloprid (Provado(R)). thiamethoxam (Actara(R)), and lambda-cyhalothrin (Warrior T(R )), were bioassayed in the laboratory and tested in the field against turni p aphid, Lipaphis erysimi (Kaltenbach) on cabbage. Results show that the LC (50)s and LC(90)s of the four insecticides for apterous L. erysimi adults w ere comparable with those for other aphid species. No indication of lambda- cyhalothrin resistance by L. erysimi was found. Results from field trails i n 1999 and 2000 showed that pirimicarb and lambda-cyhalothrin were the most effective of these insecticides, followed by imidacloprid. A field rate (2 5 g [AI]/ha) of thiamethoxam did not provide satisfactory control of L. ery simi, but the higher field rate (50 g [AI]/ha) did.