Optimisation and economic assessment of a lowcost insecticide for stored product insect pest control and seed viability

Abstract

The development of low-cost insecticidal formulations using readily available household materials presents a potential alternative to synthetic pesticides, particularly in resource-limited settings. In this study, a kerosene–salt–detergent emulsion was formulated and optimised using a Box–Behnken experimental design to evaluate its insecticidal performance against field-collected adult cockroaches and its effect on neem seed germination. Percentage insect mortality (PIM) and neem seed germination percentage (GP) were modelled as response variables using response surface methodology. The optimised mix ratio consisting of 8.29 ml of kerosene, 7.41 g of salt, and 10.56 g of detergent produced a balanced formulation that the model estimated would achieve near-complete insect mortality while maintaining acceptable seed germination. Experimental validation of the optimised mixture produced a mean observed PIM and GP of 90% each, indicating modest deviations from the model predictions. Probit analysis of knockdown data yielded an estimated LT50 of 12.0 min with a wide 95% confidence interval of 2.9–50.3 min, reflecting limited temporal resolution. Fourier-transform infrared (FT-IR) analysis identified broad functional groups consistent with the chemical composition of the formulation components. A preliminary material-cost assessment suggested that the formulation could be produced at low cost relative to some commercial insecticides. Overall, the results demonstrate a laboratory-scale proof-of-concept for a low-cost insecticidal formulation with strong knockdown potential, while highlighting the need for further species-specific efficacy testing, safety evaluation, and field validation before practical application.