Impact of insecticide application used on sugarcane crop on egg predation in the field

Abstract

Sugarcane, Saccharum officinarum L., has economic importance in Brazil and the world. In addition to its global value as the main source of sugar, energy, and ethanol, it is a raw material for several products. However, phytosanitary problems cause significant losses in the agricultural production of the crop, of which most are only due to the ineffective management of insect pests. We evaluated the impact of the application of insecticides used in sugarcane crops on the predation of eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) under field conditions. For this, cards containing 30 eggs of this species were fixed in the middle third of sugarcane plants and exposed to predation by insects present in areas sprayed with insecticides: thiamethoxam; lambda-cyhalothrin + thiamethoxam; fipronil and Metarhizium anisopliae, in addition to a control (area without spraying). The dose used for insecticides was the minimum recommended for control of insect pests in the crop. The cards remained in the areas for 24 hours after the insecticides spraying, being collected for evaluation after this period. The cards from areas sprayed with thiamethoxam; lambda-cyhalothrin + thiamethoxam and fipronil, the average number of eggs remaining was significantly higher. While in the treatments control and M. anisopliae, there was a significant reduction in the number of preyed eggs, evidencing that the chemical insecticides tested affected the rates of predation in the field, a fact not found with the biological insecticide M. anisopliae.