Using magnesium oxideglass slide method to estimate survival amount of whitefly nymphs
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Key Words：whitefly，nymph，survival，magnesium oxide glass slide method
Abstract：In this paper, a simple method was developed for estimating the amount of surviving whitefly nymphs. Honeydew droplets of nymphs may form clear round holes on magnesium oxide glass slide, which could be easily observed and counted under stereomicroscope. After the linear correlation relationship between number of nymphs (Nn) and number of droplets(Nd) was determined, nymph estimate factor(NEF) was accordingly determined, and a method of counting nymphs was proposed based on number of droplets and NEF. On tomato leaves, the NEF of 1st～2nd instar nymph, 3rd～4th instar nymph of Bemisia tabaci,(Gennadius) and the NEF of 1st～2nd instar nymph, 3rd～4th instar nymph of Trialeurodes vaporariorum(Westwood) are 7.73,5.69,518 and 5.03, respectively. Toxicity of acetamiprid to whitefiles was studied with this method. No significant difference was detected between the magnesium oxide glass slide method and the traditional method. Nevertheless the new method was more simple and exactly than the traditional method for counting survival nymphs.