Selectivity of Insecticides Against Telenomus podisi Ashmead (Hymenoptera: Platygastridae) on Corn

Abstract

Use of synthetic insecticides remains main control strategy for percevejo-marrom (Euschistus heros) in corn. However, indiscriminate use of these products can have adverse effects on the environment and human health. Thus, incorporation of bio-agents like Telenomus podisi a preferred option in corn pest management. Study was conductedto evaluate the effects of insecticides application on T. podisi mortality rates, the number of eggs parasitized by the F0 generation, and number of emergent F1 parasitoids. The insecticides tested were: imidacloprid+bifenthrin, bifenthrin+carbosulfan, thiametoxam+lambda-cyhalothrin, acephate, bifenthrin, and imidacloprid at the highest concentrations indicated for corn. Each insecticide was classified according to its selectivity, based on the methodology proposed by IOBC/WPRS. Only imidacloprid did not affect parasitoid survival however the parasitism rates of F0 females, were affected, classifying this product as slightly harmful for this biological trait. Regarding parasitoid emergence (F1), thiametoxam+lambda-cyhalothrin was classified as moderately harmful, while bifenthrin+carbosulfan and bifenthrin were considered harmful, no parasitism occurred. Thus the evaluated insecticides were classified as slightly harmful to the parasitoid T. podisi under laboratory conditions for the biological characteristics evaluated. Further studies under semi-field and field conditions are needed in order to confirm these toxicity levels on T. podisi.