![]() These reductions have not only benefited growers of Bt crops but also non-Bt farmers surrounding them who have used fewer insecticides 5, 7.Īlthough the economic benefits and reduced sprays required for Bt crops have been well documented, the potential effect of Bt crops on non-target organisms (especially natural enemies) continues to be an active area of research with ramifications for registration of Bt crops in some countries 8. Moreover, widespread adoption of Bt cotton and Bt maize has suppressed regional populations of the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae), in China 5, pink bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae), in the USA 6 and the European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), in the US 7. Studies have reported that Bt cotton and maize have provided substantial economic benefits and reduced the use of harmful insecticides with positive implications for biological control 1, 3, 4. In 2015, the number increased to 108 fields. In 2014, Bt eggplant became available in Bangladesh and 20 fields were planted with Bt eggplant 2. In 2014, 78.8 million ha of insect-resistant crops (cotton and maize) producing insecticidal crystal (Cry) proteins derived from Bacillus thuringiensis Berliner (Bt) were planted in 28 countries 1. Since genetically engineered insect-resistant crops were first commercially grown in 1996, the area planted to them has expanded rapidly. In contrast, natural enemies were not affected when fed aphids reared on Bt broccoli, thus demonstrating the safety of these Bt plants for IPM. colemani was impaired when provided with pyrethroid-treated aphids. ![]() americanus survived consumption of pyrethroid-treated aphids and that ovipositional behavior of A. Tri-trophic experiments demonstrated that no C. This indicated the aphids were not affected by the Cry proteins or the pyrethroid, thus removing any effect of prey quality. No Bt protein residues in aphids were detected and no significant differences were recorded in the performance of pyrethroid-resistant aphids that fed on Bt broccoli expressing Cry1Ab or Cry1C, or on non-Bt broccoli plants treated or not treated with the pyrethroid. We fed aphids on Bt and non-Bt plants and analyzed the Bt protein residue in aphids and compared the effects of Bt plants and a pyrethroid, lambda-cyhalothrin, on the performance of three natural enemies (predators: Coleomegilla maculata and Eupeodes americanus parasitoid Aphidius colemani) of the green peach aphid, Myzus persicae. However, pests such as aphids not susceptible to Cry proteins may require other integrated pest management (IPM) tactics, including biological control. ![]() Crops producing insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) control important lepidopteran pests.
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