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Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings Publication Acceptance Date: 6/1/1996 Publication Date: N/A Citation: N/A Interpretive Summary: The maximization of natural control is a fundamental tenet of modern integrated pest management. Natural enemies (predators and parasitoids) are an important component of this natural control. Native predators and parasitoids may be abundant in untreated Arizona cotton and may play an important role in suppressing populations of Bemisia tabaci and other cotton pests. Many historical and more recent studies have indicated that populations of many common predator and parasitoid species can be significantly reduced by the use of conventional synthetic insecticides. In 1996 two insect growth regulators (IGRs), buprofezin and pyriproxyfen, were granted emergency registration in Arizona. These compounds are known to be highly effective in suppressing whitefly populations and are generally thought to be relatively benign to natural enemies. A large-scale (80 hectares) experiment was conducted to examine the impact of these IGRs on the abundance and activity of natural enemies of whitefly relative to conventional insecticides. Parasitoid abundance and activity was enhanced in IGR fields on 4 of 10 sample dates and preliminary results for predators indicated a similar trend. These preliminary results suggest that use of IGRs for suppression of B. tabaci may help conserve populations of important natural enemies. Technical Abstract: As part of a large-scale, multi-institutional experiment in 1996 to examine and demonstrate strategies for management of Bemisia tabaci involving the use of two insect growth regulators (IGRs), we evaluated effects on the abundance and activity of native natural enemies. For parasitoids there were significant differences between insecticides regimes on 4 of 10 sampling dates. In general, parasitoid abundance and rates of parasitism were depressed in treatment plots receiving a rotation of conventional chemistry in comparison with those receiving IGRs. There was no apparent effect of any of the treatment variables on parasitoid emergence (immature survival). Results for arthropod predators are still preliminary, but densities were generally depressed in plots receiving a rotation of conventional chemistry in comparison with those receiving IGRs. These preliminary results suggest that use of IGRs for suppression of B. tabaci may help conserve populations of important natural enemies. |
