Area-wide spatial survey of the likelihood of insecticide control failure in the neotropical brown stink bug Euschistus heros

Abstract

Insecticide resistance is a well-known phenomenon caused by the intensive use of insecticides, which selected resistant individuals and cause large economic losses. The use of area-wide surveys and geostatistical analyses are important management initiatives as they enable the recognition of areas with high risks of insecticide control failure due to insecticide resistance. Here, we surveyed and mapped the risk of insecticide control failure in populations of the neotropical brown stink bug, Euschistus heros, in one of the main soybean-producing areas in the Neotropical region, the state of Goiás in central Brazil. Diagnostic bioassays were performed using the recommended label rates and minimum required control efficacy threshold for commercial formulations of the main compounds used against this pest species in the region, namely the pyrethroids beta-cyfluthrin and lambda-cyhalothrin, the neonicotinoids imidacloprid and thiamethoxam, and the organophosphate acephate. The control failure likelihood for the insecticides acephate, lambda-cyhalothrin and thiamethoxam was negligible throughout the surveyed region. However, a low risk of control failure exists for beta-cyfluthrin at localized portions of southwestern Goiás and for imidacloprid in the northeast. These findings diverge from the perceived and apparently unjustified notion that the reported insecticide control failure against this stink bug is due to insecticide resistance. Indeed, this problem is currently limited to just two insecticides (i.e., beta-cyfluthrin and imidacloprid) in circumscribed portions of the surveyed area. Thus, resistance management efforts should be specifically designed to address these areas, and more general approaches should continue to be employed in the whole of the region.