Ecological and physiological features of Bt-plants causing outbreaks of secondary pests

Resumo

Reduction in the area occupied with Bt-crops caused by their cost inefficiency largely depends on the outbreaks of secondary pests. Among them, a highly important place belongs to the representatives of the order Hemiptera. These phytophages are insensitive to Cry-proteins of genetically modified (GM) insecticidal crops engineered to control the main pests from the orders Lepidoptera and Coleoptera with chewing mouthparts. In contrast to chewing, evolutionary more advanced piercing-sucking mouthparts of Hemiptera phytophages do not initiate in plants the state of induced defense associated with an elevated content of terpenes. When the main pest is absent, a reduced content of terpenes in Bt-crops makes them more attractive to hemipterans than conventional cultivars. In the absence of the main pest there’s no competition for hemipterous secondary pests. In aggregate, these two factors bring about outbreaks of Hemiptera in Bt-crops.