Dual-function trehalose transporters link metabolic adaptation to diapause plasticity and fecundity in Trichogramma...

Trehalose transporters (Trets) play a pivotal role in mediating metabolic adaptation in insects by regulating trehalose distribution across tissues. However, their functional differentiation and contribution to key life-history traits such as diapause and reproduction remain poorly understood in parasitoid wasps. In this study, we investigated two trehalose transporter genes, Tret1 and Tret1-2, in the parasitic wasp Trichogramma dendrolimi, an important biological control agent. Using stage-specific RNA interference, we demonstrated that knockdown of either gene significantly impaired diapause induction and delayed larval-prepupal transition, accompanied by downregulation of trehalose-6-phosphate synthase and trehalose content. Moreover, Tret1 silencing broadly suppressed the expression of juvenile hormone epoxide hydrolase and ecdysone receptor (EcR), whereas Tret1-2 knockdown specifically reduced EcR transcript levels. Intriguingly, only adult-stage silencing of Tret1-2 severely compromised female fecundity, reducing both ovarian egg load and total number of parasitized eggs, and led to disrupted ovarian morphology and downregulation of vitellogenin receptor (VgR). These results reveal that Tret1 and Tret1-2 have evolved specialized, stage-specific functions: Tret1 primarily supports larval development and diapause preparation, while Tret1-2 is essential for adult reproductive performance, likely through regulating VgR-mediated oogenesis. Our findings provide novel insights into the functional divergence of trehalose transporters in linking metabolic reprogramming to diapause plasticity and fecundity in a parasitoid wasp, with implications for improving its mass rearing and field application in biological control programs.