Occurrence of Molecularly Diverse Bt Cry Toxin-Resistant Mutations in Insect Pests of Bt + Corn and Cotton Crops and Remedial Approaches

Cultivation of Bt⁺ genotypes has dispensed with insecticidal sprays and thereby corn and cotton farmers have hugely benefited worldwide. Recent recordings of genetically diverse Cry-resistance in insect pests of Bt⁺ corn and cotton fields have raised grave concern. Curiously, bulk of Cry-resistant pink bollworms found in certain Bt⁺ cotton fields in India proved homozygous for multiple linked mutations. Besides, dominantly inheritable Cry-resistance and cross resistance between different Cry-proteins have also been noted. To stem evolution of resistance against antiinsect protein-toxins, new nematology research on IPM procedures, complementary to refuge and Cry stacking technologies is imminently needed.