Comparative Efficacy of Insecticides and Nanoparticle-Based Biocontrol Agents Against Pink Bollworm in Cotton

Abstract

The pink bollworm (Pectinophora gossypiella) has resurged as a major threat to cotton production in South Asia due to widespread resistance to Bt toxins (Cry1Ac and Cry2Ab) and conventional insecticides, causing 20–40% yield losses, reduced seed weight/oil content, and delayed boll opening. This review compares the efficacy of synthetic insecticides (organophosphates, pyrethroids, spinosyns) with emerging nanoparticle-based biocontrol agents. Conventional formulations such as Profenofos + Cypermethrin provide strong knockdown but face limitations from internal larval feeding, diapause, and resistance development, with field trials showing variable exit holes and locule damage. Nanoparticle approaches including silver (AgNPs), zinc oxide (ZnO NPs), silica (SiO₂ NPs), and chitosan (ChNPs) offer multi-modal action through ROS generation, cuticular abrasion, dehydration, and controlled release. Green-synthesized nanoparticles demonstrate lower LC₅₀ values, enhanced foliar adhesion, prolonged residual activity, and reduced non-target effects compared to bulk chemicals. Silica NPs achieve rapid physical mortality, while chitosan enhances delivery and elicits plant defense. Although laboratory results are promising (high mortality at low concentrations), field validation remains limited. Integrated deployment within IPM frameworks, combining pheromones, botanicals, and nano-formulations, represents a sustainable strategy to mitigate resistance, lower environmental impact, and support smallholder resilience in Pakistan and India. Regulatory advancements in China and India further favor nano-enabled solutions for 2025–2030.