Insight into the regulation of the <scp>Nrf2</scp> pathway in response to ascovirus infection in <i>Spodoptera exigua</i>

<jats:title>Abstract</jats:title><jats:sec><jats:title>BACKGROUND</jats:title><jats:p>Ascoviruses are a type of entomopathogenic microorganism with high biological pest control potential and are expected to contribute to the natural control of lepidopteran pests. However, knowledge of the molecular mechanism underlying the biocidal activity of ascovirus on its host insects remains limited.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>In this study, the relative enzyme activity of superoxide dismutase and peroxidase, as well as the expression level of <jats:italic>Spodoptera exigua peroxidase</jats:italic> (<jats:italic>SePOD</jats:italic>), were found to be significantly increased at 6 h post infection with Heliothis virescens ascovirus 3h (HvAV‐3h). H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> accumulation and enhanced expression of <jats:italic>NADPH Oxidase</jats:italic> (<jats:italic>SeNOX</jats:italic>) were also observed. In addition, <jats:italic>Nuclear Factor erythroid 2‐Related Factor 2</jats:italic> (<jats:italic>SeNrf2</jats:italic>) and <jats:italic>muscle aponeurosis fibromatosis</jats:italic> (<jats:italic>SeMaf</jats:italic>) were overexpressed following infection with HvAV‐3h. Silencing of <jats:italic>SeNrf2</jats:italic> decreased the expression of <jats:italic>SePOD</jats:italic>, whereas the mortality of <jats:italic>SeNrf2‐</jats:italic>silenced larvae and viral genome copy number also increased. Further RNA interference of <jats:italic>SeNOX</jats:italic> significantly decreased expression of <jats:italic>SeNrf2</jats:italic> and <jats:italic>SePOD</jats:italic> and therefore increased the mortality and viral genome copy number of the ascovirus‐infected host.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSION</jats:title><jats:p>The HvAV‐3h activated Nrf2/ARE pathway of <jats:italic>S. exigua</jats:italic> and reactive oxygen species were found to respond to ascovirus infection by regulating alterations in antioxidant enzyme genes mediated by the host Nrf2/ARE pathway. These findings enhance our knowledge of ascovirus–host interactions and lay the foundation for the application of ascoviruses in biological pest control. © 2022 Society of Chemical Industry.</jats:p></jats:sec>