Insect-Resistant Variety Populus deltoides ‘Shalinyang’ May Decrease Anoplophora glabripennis Females’ Fecundity by Suppressing the Serine/Threonine Kinase AglaAkt Gene

<i>Anoplophora glabripennis</i> Motschulsky (Coleoptera: Cerambycidae) is notorious for its wide host range, serious damage caused, and the difficulties involved in controlling it. <i>Populus deltoides</i> 'Shalinyang' (PdS) has demonstrated a strong inhibitory effect on the larval growth and the adult lifespan of <i>A. glabripennis</i> and can be used as an "attract-and-kill" tree in mixed shelterbelt construction. However, how <i>A. glabripennis</i> react to this resistant poplar remains unclear. This research employed transcriptomics techniques to study transcriptional responses in the midgut of <i>A. glabripennis</i> after consuming PdS, <i>Elaeagnus angustifolia</i> L. (EA), and <i>Salix matsudana</i> Koidz (SM), respectively. One of the key findings revealed that the PIK3-Akt signaling pathway was suppressed in <i>A. glabripennis</i> feeding on PdS compared with those feeding on EA or SM. Further RNA interference results demonstrated that silencing the <i>AglaAkt</i> gene significantly decreased the levels of AKT, phospho-AKT, vitellogenin, vitellogenin receptor, and vitellin in <i>A. glabripennis</i>. Therefore, we speculate that the <i>AglaAkt</i> gene may be an underlying target gene that causes the low reproductive capacity of <i>A. glabripennis</i> when feeding on PdS. This finding provides important insights into the role of the <i>AglaAkt</i> gene in mediating the reproductive development in <i>A. glabripennis</i> and its molecular response to the resistant poplar.