Side effects of insecticides used in soybean and corn for the egg parasitoid Telenomus remus (Hymenoptera: Scelionidae)

Abstract

Spodoptera frugiperda (Lepidoptera: Noctuidae) is one of the main pests of corn and soybean crops. Its control is carried out through insecticide applications that often cause biological imbalances with population reduction of natural enemies. One of the natural enemy species associated with this noctuid is the egg parasitoid Telenomus remus (Hymenoptera: Scelionidae). The objective was to evaluate the side effects of the insecticides chlorantraniliprole, indoxacarb, spinetoram, and chlorpyrifos, at the highest dosages recommended by the manufacturers, aiming to integrate chemical and biological methods. The insecticides were sprayed on eggs of S. frugiperda containing T. remus in its immature phase (egg-larva period and pupal stage) and adult stage. The design used was completely randomized. The number of surviving insects, parasitized eggs, emerged parasitoids, and males and females were evaluated. The insecticide chlorpyrifos reduced parasitism and emergence of insects in the F1 generation by 100% when applied to eggs of S. frugiperda containing T. remus during the egg-larva period and pupal stage, being classified as harmful according to the toxicological classification of IOBC. The other insecticides were selective for the parasitoid in its immature phase. The insecticides spinetoram and chlorpyrifos were toxic to adult females (F0) of the parasitoid exposed to residues of the insecticides on contaminated surfaces. Due to the low toxicity of the insecticides chlorantraniliprole, spinetoram, and indoxacarb to T. remus in its immature phase, and the insecticides indoxacarb and chlorantraniliprole to the adult stage, these insecticides should be prioritized in integrated management programs for S. frugiperda.