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Submitted to: Silverleaf Whitefly: 1997 Supplement to the Five Year National Research and
Publication Type: Abstract Only Publication Acceptance Date: 8/1/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: A large-scale, multi-institutional study was initiated in 1996 to examine and demonstrate strategies for Bemisia management involving the use of two new insect growth regulators (IGR). The study involved three different insecticide regimes, three action threshold levels for initiating insecticide treatments, and application by either air or ground equipment. A key component of these studies was examination of the effects of these management systems on the abundance and activity of native natural enemies Weekly sweepnet samples were used to estimate the abundance of arthropod predators, and leaf samples were used to estimate the abundance and activity of whitefly parasitoids. Predators will be subject to serological analyses to examine relative frequency of predation on Bemisia in relation to insecticide regime. At present, predator samples are being processed. Preliminary results indicate that the parasitoids Eretmocerus nr. californicus and Encarsia meritoria were present throughout the season. Application method and action threshold level appeared to have little effect on parasitoid abundance and activity. Rates of parasitism reached 75 p in some plots and was higher on a number of sample dates throughout the season in plots sprayed with either buprofezin or pyriproxyfen in comparison with those treated with mixtures of conventional insecticides. A severe storm in late July severely depressed populations of both host and parasitoids. |
