Development of pyridalyl nanocapsule suspension for efficient management of tomato fruit and shoot borer (<i>Helicoverpa armigera</i>)

Abstract

The objective of this study was to evaluate in vitro the insecticidal activity of pyridalyl nanosuspension in comparison to technical material and commercial formulation against larvae of Helicoverpa armigera. Suspension of pyridalyl nanocapsules was prepared, for reducing its dose of application. Compatibility of pyridalyl with sodium alginate was ascertained and a formulation was obtained by optimizing various parameters. Average micelle size of different formulations was around 138 nm and size of pyridalyl was less than 100 nm. Spherical shape and nanosize of capsules was confirmed by Transmission electron microscopy. Zeta potential of optimized formulation was found to be about (−)20 ± 1 Mv indicating acceptable range for expressing physical stability of the nano-capsules. The pyridalyl nanosuspension insecticidal activity increased remarkably, with LC50 values of 40 μg mL−1 in comparison to LC50 values of technical material (90 μg mL−1) and commercial product (250 μg mL−1). Bioassay results by leaf dip method showed that nanoformulation is 2.26 and 6.25 times more effective against H. armigera as stomach poison than the technical product and commercial formulation respectively. By topical method, the LC50 values obtained were 80, 150, and 250 μg mL−1 for nanoformulation, technical material, and commercial formulation, respectively, proving our hypothesis. Pyridalyl nanocapsule suspension performed effectively than technical material and commercial product against tomato fruit and shoot borer (Helicoverpa armigera), showing that insecticide load to the environment can be reduced by using nanoformulations.