A procedure for comparing the efficacy of insecticides for greenhouse whitefly control

摘要

Five insecticides, tau-fluvalinate ((96 mg/litre), imidacloprid (50, 1000 or 150 mg/litre) and three "organic" insecticides YR55 (1.2 g/litre), YR65 (1 m1/litre) and YR 70(3.6 g/litre), as well as water control were applied three times (10 and 8 days apart) to Mexican sun flower plants (Tithonia rotundifolia). Each plant had four tagged leaves infecsted with either eggs, first instar nymphs, third instar nymphs or puparia of greenhouse whitefly (Trialeurodes vaporariorum). Mortality was assessed after whitefly passed to the next growth stage. YR55 gave poor control of all whitefly stages while YR70 gave moderate control of all stages. The other insecticides gave good control when leaves were initially infested with eggs and first instar nymphs. Imidacloprid and YR65 gave better control of whitefly than tau-fluvalinate where leaves were initially infested with third instar nymphs and puparia. Tagged leaves infested with cohorts of juvenile whitefly provided an efficient method to assess the efficacy of the pesticides.