Evaluation of co-nanoencapsulation process on the toxicity and biochemical metabolism of imidacloprid and lambda-cyhalothrin in Myzus persicae (Sulzer)

The aphid Myzus persicae (Sulzer) is one of the most economically important plant pests worldwide. Excessive use of chemical pesticides to control this pest affects its successful management. In this study, we used a novel technology to improve insecticide efficacy while reducing doses through the combination of insecticides. Therefore, the joint action of pyrethroid lambda-cyhalothrin (LAM) and neonicotinoid imidacloprid (IMI) was evaluated on the aphid M. persicae using leaf-dipping method. Co-nanoencapsulated formulation of these insecticides was prepared using phosphatidylcholine and chitosan as carrier and surface-coating material, respectively. The results of toxicological studies revealed a considerable synergistic effect at 2:1 ratio of technical grade IMI plus LAM and their co-encapsulated formulation. Nanoparticles produced were spherical with size of 67.56 nm. The LC₅₀ values for the technical grade of IMI, LAM and their mixture were 12.65, 89.82 and 4.07 mg ai l⁻¹; for co-encapsulated formulation, the value was 7.06 mg ai l⁻¹. To evaluate the effect of co-nanoencapsulation process on detoxification enzymes, the activities of general esterases and glutathione S-transferases and the amount of cytochrome P450s were measured in M. persicae. The technical grade mixture of IMI and LAM caused pronounced changes in the levels of all tested enzymes compared with the control. In contrast, co-nanoencapsulation protected IMI and LAM from cytochrome P450s- and glutathione S-transferase-induced enzymatic degradation. Considering the toxicological and biochemical findings, co-nanoencapsulation can be valuable as an eco-friendly method for improving the efficacy of the insecticides while preserving the synergistic effects and protecting the active ingredients against detoxification enzymes.