Knockdown of <i>AisHSP19.6</i> by RNA Interference Increases Susceptibility to Three Insecticides in <i>Agrotis ipsilon</i>

In insects, heat shock proteins (HSPs) are crucial for protecting against environmental stressors, particularly insecticides. However, in the important agricultural pest Agrotis ipsilon, the specific protective function provided by HSPs against different insecticides remains unclear. Herein, we identified a small HSP (sHSP) gene in A. ipsilon: AisHSP19.6. Peak AisHSP19.6 expression occurred during the sixth-instar larval stage in the larval midgut. Treatment with phoxim (PHO), lambda-cyhalothrin (LCT), and chlorantraniliprole (CAP) causes oxidative stress in A. ipsilon larvae. Furthermore, PHO, LCT, and CAP exposure, as well as H₂O₂ injection, significantly elevated AisHSP19.6 transcription. Although AisHSP19.6 did not metabolize PHO, LCT, and CAP, it protected the cells from oxidative stress. Moreover, A. ipsilon larvae in which AisHSP19.6 was silenced using RNA interference (RNAi), exhibited a significantly higher mortality rate in response to PHO, LCT, and CAP exposure relative to AisHSP19.6-expressing larvae. This study provides new insights into sHSP-mediated insecticide susceptibility in A. ipsilon. These findings also provide a potential RNAi-based strategy for the management of this agricultural pest.