Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada.
BMC Res Notes. 2022 Jun 20;15(1):211. doi: 10.1186/s13104-022-06102-3.
Group-living plays a key role in the success of many insects, but the mechanisms underlying group formation and maintenance are poorly understood. Here we use the masked birch caterpillar, Drepana arcuata, to explore genetic influences on social grouping. These larvae predictably transition from living in social groups to living solitarily during the 3rd instar of development. Our previous study showed a notable shift in the D. arcuata transcriptome that correlates with the transition from grouping to solitary behavior. We noted that one differentially regulated gene, octopamine receptor gene (DaOAR), is a prominent 'social' gene in other insect species, prompting us to test the hypothesis that DaOAR influences grouping behavior in D. arcuata. This was done using RNA interference (RNAi) methods by feeding second instar larvae synthetic dsRNAs.
RT-qPCR analysis confirmed a significant reduction in DaOAR transcript abundance in dsRNA-fed larvae compared to controls. Behavioral trials showed that caterpillars with reduced transcript abundance of DaOAR remained solitary throughout the observation period compared to controls. These results provide evidence that regulation of the octopamine receptor gene influences social grouping in D. arcuata, and that specifically, a decrease in octopamine receptor expression triggers the larval transition from social to solitary.
群居在许多昆虫的成功中起着关键作用，但群体形成和维持的机制还知之甚少。在这里，我们使用蒙面桦尺蛾（Drepana arcuata）来探索对社会群体形成的遗传影响。这些幼虫在发育的第 3 龄期，会从群居状态可预测地转变为独居状态。我们之前的研究表明，与从群居行为转变为独居行为相关的 D. arcuata 转录组发生了显著变化。我们注意到，一个差异调控的基因，即章鱼胺受体基因（DaOAR），是其他昆虫物种中重要的“社会性”基因，这促使我们测试 DaOAR 是否影响 D. arcuata 的群居行为这一假设。这是通过用第二龄幼虫喂食合成 dsRNA 的 RNA 干扰（RNAi）方法来完成的。
实时 qPCR 分析证实，与对照组相比，dsRNA 喂养的幼虫中 DaOAR 转录本丰度显著降低。行为试验表明，与对照组相比，DaOAR 转录本丰度降低的幼虫在整个观察期内仍保持独居状态。这些结果表明，章鱼胺受体基因的调控影响了 D. arcuata 的社会群体形成，具体来说，章鱼胺受体表达的减少触发了幼虫从社会到独居的转变。
