Thermo-Responsive Quaternary Ammonium Chitosan Nanocapsules with On-Demand Controlled Pesticide Release and Maximally Synergistic Biological Activity

Pesticides play an important role in pest control. However, they can be limited due to low utilization efficiency, causing substantial losses to the environment and ecological damage. Nanotechnology is an active area of research regarding encapsulation of pesticides for sustainable pest control. Here, we developed intelligent formulations of avermectin (Av) quaternary ammonium chitosan surfactant (QACS) nanocapsules (i.e., Av–Th@QACS) with on-demand controlled release properties, toward ambient temperature and maximal synergistic biological activity of Av and QACS. The Av–Th@QACS regulated the quantity of pesticide release in accordance with the ambient temperature changes and, insofar as this release is a means of responding to variations in pest populations, maximized the synergistic activity. In addition, the Av–Th@QACS were highly adhesive to crop leaves as a result of the prolonged retention time on the crop leaves. Therefore, Av–Th@QACS exhibited greater control against aphids at 35 °C than at 15 and 25 °C. Compared with commercial formulations, Av–Th@QACS was more toxic at 35 °C and less toxic at 15 °C. Thus, researchers can apply Av–Th@QACS as intelligent nanopesticides with an on-demand, controlled release and synergistic biological activity and, in so doing, prolong pesticide duration and improve the utilization efficiency.