Transcriptomic analysis under the stress of insecticides and the functional role of three genes related to host...

The female parasitoid wasp Scleroderma sichuanensis (Hymenoptera: Bethylidae) utilizes various intricate behavior strategies, including host detection, learning, and memory, to enhance its survival and reproductive success. RNA-Seq analysis conducted under sublethal insecticide stress identified three differentially expressed genes, SsOR5, SsGRIN2B, and SsPDE8A, selected for functional validation due to their likely roles in host searching behavior. The SsOR5, an odorant receptor, is believed to interact with other olfactory receptors and downstream signaling molecules to improve host detection. In contrast, SsGRIN2B, an NMDA-type glutamate receptor, may influence synaptic plasticity and neural transmission, thereby affecting leering behavior. Additionally, SsPDE8A modulates cAMP-dependent signaling pathways, which are crucial for memory consolidation and behavioral response. This research investigates these genes in S. sichuanensis using RNA interference (RNAi) to assess changes in host finding efficiency. Adult female wasp received dsRNA treatments at doses of (0.5 μL, 1 μL, and 3 μL) and time durations (12, 24, 48, and 72 h), with the most significant gene silencing observed at 3 μL for 48-72 h. Behavioral assays conducted with a Y-tube olfactometer revealed that knockdown of SsOR5 significantly reduced host attraction, while knockdown of SsGRIN2B and SsPDE8A led to moderate reeducations, highlighting the varying contributions of these genes to olfactory drive behavior. This study demonstrates that insecticides induced changes in gene expression can disrupt neural and olfactory pathways essential for host location, and emphasizes the potential of RNAi-based approaches to target behaviorally significant genes, offering new strategies for parasitoid-mediated pest management.