ECOLOGY AND BEHAVIOR Trichogramma (Hymenoptera: Trichogrammatidae) Ecology in a Tropical Bt Transgenic Cotton Cropping System: Sampling to Improve Seasonal Pest Impact Estimates in the Ord River Irrigation Area, Australia
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چکیده
Trichogramma Westwood (Hymenoptera: Trichogrammatidae) cause high mortality rates in the potentially resistant pest species, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), and are considered integral to the resistance management plan for Bacillus thuringiensis transgenic cotton, Gossypium hirsutum L., production in the Ord River Irrigation Area (ORIA), WesternAustralia.Measured as percentage of parasitism,Trichogramma activity seems highly variable over time; yet, it contributes signiÞcantly to pest suppression at peak insect pest density. Environmental constraints on Trichogramma survival, especially insecticide applications, may limit their effectiveness. The decision to initiate insecticide applications in ORIA cotton crops is best delayed unless absolutely necessary to avoid disruption of Trichogramma impact on pests. Trichogramma disperse into young crops and display high intrinsic rates of increase effectively stißing Helicoverpa (Hardwick) population increase after initial egg lay during high-density years in the ORIA, and evidence suggests a possible preference for H. armigera host eggs.
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