Magnetic Hydrogel Microrobots as Insecticide Carriers for In Vivo Insect Pest Control in Plants

The cost of insect pests to human society exceeds USD70 billion per year worldwide in goods, livestock, and healthcare services. Therefore, pesticides are needed to prevent insect damage despite the secondary effects of these chemical agents on non‐target organisms. Chemicals encapsulation into carriers is a promising strategy to improve their specificity. Hydrogel‐based microrobots show enormous potential as chemical carriers. Herein, hydrogel chitosan magnetic microrobots encapsulating ethyl parathion (EP)‐CHI@Fe3O4 are used to efficiently kill mealworm larvae (Tenebrio molitor). The mechanism takes advantage of pH‐responsive chitosan degradation at Tenebrio molitor midgut pH to efficiently deliver pesticide into the mealworm intestinal tract in just 2 h. It is observed that under a transversal rotating magnetic field, mealworm populations show higher mortality after 30 min compared to free pesticide. This example of active pesticide carriers based on soft microrobots opens new avenues for microrobots applications in the agrochemical field as active chemical carriers. Hydrogel‐based magnetic microrobots are used as pesticide carriers for chemical delivery in vivo. Pest insect larvae are controlled by pH‐responsive pesticide liberation from hydrogel magnetic microrobots in larvae digestive track. Pesticide carriers are seeded in mealworm food, after food ingestion, pesticide is released by microrobots dissolution in the acid pH of larvae midgut. Pesticide release is enhanced by microrobots magnetic actuation allowing 100% larvae mortality after 2 h.