Maternal Juvenile Hormone Transfer is Associated with Diapause Fate Determination in the Parasitoid Wasp Nasonia Vitripennis.

Insects inhabiting temperate regions use photoperiodic cues to predict seasonal changes and regulate diapause. In some species, maternal photoperiodic experience determines offspring diapause fate. However, the physiological mechanisms underlying transgenerational transmission of seasonal information remain poorly understood. In the parasitoid jewel wasp Nasonia vitripennis, females exposed to long-day conditions produce offspring that develop continuously, whereas those exposed to short-day conditions produce offspring destined for diapause. Previous studies have shown that maternal juvenile hormone (JH) levels increase under long-day conditions and promote non-diapause development in offspring, suggesting that JH may participate in the transfer of maternal photoperiodic information. Here, we investigated whether this effect is mediated through canonical maternal JH signalling pathways or through changes in egg endocrine state. RNA interference-mediated silencing of methoprene-tolerant, taiman, and krüppel-homologue 1 did not alter offspring diapause fate. In contrast, eggs from long-day females contained significantly higher JH III levels than those from short-day females, and topical application of JH III to eggs from short-day females promoted non-diapause development. These findings suggest that photoperiod-dependent variation in egg JH levels contributes to offspring diapause determination and support a role for egg endocrine state as an intermediary between maternal environmental perception and offspring developmental fate.