Dose-dependent toxicity and field efficacy of PEG-emulsified botanical formulations against chickpea pod borer (Helicoverpa armigera)

The present study aimed to develop and evaluate the efficacy of Polyethylene Glycol (PEG)-based emulsion formulations using botanical seed extracts against Helicoverpa armigera. Seed extracts from Pongamia pinnata, Pachyrhizus erosus, Annona squamosa, and Ricinus communis were prepared in methanol or ethyl acetate and formulated into emulsion using PEG 200 and Tween 20 as surfactant blends. Laboratory bioassays were conducted using a leaf/seed dip method under controlled conditions, and larval mortality was recorded at 24, 48, and 72 h. Probit analysis was performed to determine LD₅₀ and LD₉₀ values. Bio-efficacy trials (pooled data) revealed that P. pinnata 10% PEG-based formulation showed the highest larval mortality, recording 86.33% reduction in larval population and showed a yield of 11.83 q/ha, comparable to the chemical control (12.62 q/ha). These formulations also demonstrated acceptable physicochemical stability under storage conditions. These findings indicate that PEG-based botanical formulations, particularly those derived from P. pinnata and P. erosus, hold promise as effective, environmentally benign alternatives to conventional insecticides.