Evolution of BT Resistance in Lepidopteran Pests: Patterns, Drivers, and IPM Strategies

Abstract

Bacillus thuringiensis (Bt) based transgenic crops and bioinsecticide formulations have become central tools in controlling lepidopteran pests in cotton, maize, soybean as well as various vegetable systems worldwide. Large scale utilizationhas significantly reduced insecticide use, increased crop yields and brought tremendous economic gains to the growers and society. Extensive adoption of Bt toxins has reduced pesticide use, thus making the longevity of Bt technology development defining challenge for modern pest control. Resistance has been reported in field populations of lepidopteran pests including, Corn earworm Helicoverpa zea, European corn borer Ostrinia nubilalis, Pink bollworm Pectinophora gossypiella, Cotton bollworm Helicoverpa armigera, Diamond backmoth Plutella xylostella, and Fall armyworm Spodoptera frugiperda. This review summarizes the existing information on the Bt resistance development in lepidopteran pests combining molecular, physiological, ecological, and agronomic insights. It identifies the properties and distribution patterns of Bt toxins, summarizes global resistance spread, and also discusses resistance mechanisms including modified midgut receptors and proteolytic processing and detoxication mechanisms, as well as interactions between microbiomes and the toxins. The review further explores ecological and agronomic determinants, such as refuge structure, cropping practices, landscape organization and farmer’s choice. Advances in monitoring, diagnostics and modeling of resistance evolution and emerging strategies for integrating Bt technologies into integrated pest management (IPM) frameworks for sustainable control.