Sampling protocol to detect Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in mixed species populations in greenhouse vegetable crops

摘要

Current sampling protocols for pest whitefly in greenhouse cropping systems are not adequate for detection of Bemisia tabaci when it is part of a mixed species population. Greenhouse vegetable and flower crops in the north, west and south of Sydney were sampled for fourth-instar whitefly nymphs in autumn, winter and spring of 2007. Bemisia tabaci was found in all regions: in the north in winter, the west in all seasons and the south in autumn and winter. A comparison of a Poisson model for pest abundance and a binomial model of presence/absence showed the same factors to be significant, indicating that it is sufficient to sample for presence/absence of the pest on individual plants, rather than to measure pest abundance per plant. A model using the binomial distribution determined that if more than 20% of plants are infested with B. tabaci, a sample size of 20 whole plants per greenhouse is sufficient to detect the presence of B. tabaci with greater than 95% confidence.