Sex-dependent body mass and respiratory responses on Euschistus heros individuals resistant to imidacloprid

Abstract

In insect-resistant populations, adaptive fitness is intimately related to the physiological responses of males and females to different stressors.By using laboratory-selected imidacloprid-resistant individuals of the Neotropical brown stink bug Euschistus heros, one of the most prevalent pests in soybean fields in the Neotropical region, we evaluated whether resistance to imidacloprid (synergized by piperonyl butoxide—PBO) would differentially affect the longevity, body mass and respiratory responses of E. heros males and females.We used an imidacloprid-susceptible E. heros strain (ImiSusc), whose individuals were reared under controlled and imidacloprid-free conditions for over a decade, to select the PBO-synergized imidacloprid-resistant strain (ImiPBOSel).After eight generations using PBO-synergized imidacloprid, our results revealed that resistant individuals exposed only to dry residues of imidacloprid (tarsal contact) could survive at concentrations as high as 168 μg a.i./cm2, which is equivalent to 40-fold the label recommendation for field applications. Furthermore, ImiPBOSel males and females exhibited higher longevity, higher body mass and elevated respiratory activity than ImiSusc individuals.Altogether, the findings described here showed that imidacloprid resistance can select E. heros individuals with better metabolic capacities, which can complicate the management of this pest under field conditions.