Control of greenhouse whitefly,Trialeurodes vaporariorumon gerberas by systemic application of acephate

摘要

AbstractA linear relationship (r2= 0.99) was found between the concentration of acephate in the nutrient solution applied to gerberas (Gerbera jamesoniiH. Bollus ex Hook. f) grown in perlite and the mortality of nymphs of greenhouse whitefly,Trialeurodes vaporariorumWestwood. The LD50for this method of application was 84 mg litre−1. A single irrigation with 180 mg litre−1acephate killed all nymphs in 10 days without apparent damage to plants. At 120 mg litre−1, acephate accumulated readily in leaves, reaching a maximum concentration of 11 mg kg−1dry matter on the third day of treatment. Concentrations in leaves then fell gradually, reaching 50 of the maximum concentration seven days later. Methamidophos was first detected in leaves approximately a day later than acephate. A maximum concentration of 9 mg kg−1dry matter was recorded on day 5 after which the concentration slowly fell. The half‐life of methamidophos was estimated to be 11 days. The systemic use of acephate for the control of greenhouse whitefly and its relevance to Integrated Pest Management (IPM) programmes for pests of ornamental plants ar