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Ecological Effects of Transgenic Crops: Non-target Effects in Bt Cotton

Ecological Effects of Transgenic Crops: Non-target Effects in Bt Cotton. This presents the results of research only. Mention of a proprietary product does not constitute endorsement or recommendation for its use by USDA. Steven E. Naranjo USDA-ARS Phoenix, Arizona & Peter C. Ellsworth

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Ecological Effects of Transgenic Crops: Non-target Effects in Bt Cotton

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  1. Ecological Effects of Transgenic Crops: Non-target Effects in Bt Cotton This presents the results of research only. Mention of a proprietary product does not constitute endorsement or recommendation for its use by USDA. Steven E. Naranjo USDA-ARS Phoenix, Arizona & Peter C. Ellsworth University of Arizona, Maricopa, Arizona

  2. Pest Complex - Western U.S. Cotton Key Pests Sporadic and Minor Pests Cotton bollworm Tobacco budworm Armyworms Loopers Cotton leafperforator Saltmarsh caterpillar Cutworms Fleahoppers Plant bugs Stink bugs Cotton aphid Thrips Spider mites Pectinophora gossypiella Bemisia tabaci Lygus hesperus

  3. Insecticide Use PatternsArizona Cotton Bt cotton Insect growth regulators Ellsworth and Jones 2000

  4. Selective Insecticide UseArizona Cotton

  5. Natural Enemy Complex -Western U.S. Parasitoids Predators 30+ species Hyposter Copidosoma Microplitis Lysiphlebus Chelonus Lespesia Eretmocerus Encarsia Anaphes Leiophron 50+ species Geocoris Orius Nabis Zelus Collops Hippodamia Drapetis Chrysoperla Labidura Misumenops

  6. Natural Enemies – Pectinophora gossypiella Predators 23 species described 9 species (immunological ID) Parasitoids 4 native species described (rare) 16 exotic species introduced (0 established)

  7. Function Abundance Diversity Non-Target Effects (Arthropods)

  8. General MethodsNon-target abundance/diversity • Replicated experimental studies at MAC • Treatments: • Bt cotton / conventional cotton • Unsprayed for any pest • Insecticides for all pests as needed • Sampling by sweep nets, beat buckets, whole plants, pitfall traps • ANOVA, EstimatorS V. 5 (Colwell) for diversity analyses

  9. Natural Enemy Abundance

  10. Non-Bt Bt cotton Natural Enemy AbundanceNo Insecticides 4530 5611 1999 0.28 0.40 0.34 0.03 0.98 0.37 0.24 0.57 0.08 0.39 2000 0.89 0.18 0.66 0.70 0.16 0.23 0.16 0.51

  11. Bt cotton Non-Bt Natural Enemy AbundanceNo Insecticides P = 0.18 P = 0.29

  12. Bt cotton Non-Bt Unsprayed Sprayed Natural Enemy AbundanceInsecticides as Needed (e.g. 1999)

  13. Arthropod Community Structure

  14. Community Structure – Pitfall Traps(Bt vs. Non-Bt) 68 70 57 57

  15. Community Structure – Pitfall Traps(Sprayed vs. Unsprayed) 68 69 74 40

  16. Natural Enemy Function

  17. MethodsNatural Enemy Function • Replicated experimental studies at MAC • No insecticides • Estimate rates of predation and parasitism • Sentinel pink bollworm egg masses (20 per plot) • Life tables for whiteflynymphs (50 per plot)

  18. Natural Enemy FunctionPredation on Pink Bollworm Eggs

  19. Natural Enemy FunctionMortality of Whitefly Nymphs

  20. Conservation Biological ControlAn Example Whitefly IPM in Cotton Natural Enemies Bt Cotton IGRs

  21. Impact of Conservation 1997

  22. Thanks to Virginia Barkley Kim Beimfohr Becci Burke Melanie Charney Scott Davis Ghislaine Majeau Ruben Marchosky Greg Owens Jeffrey Rivas Doug Sieglaff

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