The meadow moth Loxostege sticticalis is a serious agricultural pest that feeds on the leaves of many economic crops, such as sugar beet, soybean, sunflower, and potato. In addition to the rapid migration of adult moths, the collective foraging behavior of the larvae is also thought to be involved in the search for new food sources and substantially contributes to the expansion of the infested area. However, whether and how the chemical signals take part in this process remains unknown. In this study, two larva-specific expressed odorants, LstiOR5 and LstiOR6, were successfully cloned and deophanized. A heterologous study on Xenopus laevis oocytes showed that several host plant volatiles could evoke LstiOR responses in a dose-dependent manner. One herbivore-induced plant volatile (HIPV) of soybean leaves, methyl salicylate (MeSA), exerted attractive effects on the L. sticticalis larvae at all tested concentrations. Further foraging choice assays showed that the L. sticticalis larvae preferred foraged soybean leaves over unforaged leaves. When MeSA was artificially added to unforaged leaves, the unforaged leaves were preferred over the foraged leaves. In addition, GC-MS analysis demonstrated that MeSA was induced by the foraging behavior of the larvae and acted as a collective food signal in L. sticticalis. Moreover, in situ hybridization showed that LstiOR5 was highly expressed in larval antenna neurons. When LstiOR5 was silenced, both the electrophysiological response of the antenna to MeSA and the preference for foraged leaves were significantly decreased, suggesting that LstiOR5 is involved in the collective foraging behavior of L. sticticalis. Our results clarified the chemical signals that trigger the collective foraging behavior of L. sticticalis and provided more evidence for the molecular mechanism underlying the expansions of their infested areas at a peripheral olfactory sensing level. These findings could facilitate the development of potential control strategies for controlling this pest and provide a potential gene target that correlates with the collective foraging behavior of L. sticticalis, which might lead to better pest management.

中文翻译：

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草食动物诱导的宿主植物挥发物可作为对草地蛾Loxostege sticticalis（鳞翅目：Pyralidae）幼虫的集体觅食信号。

草地蛾Loxostege sticticalis是一种严重的农业害虫，以许多经济作物的叶子为食，例如甜菜，大豆，向日葵和马铃薯。除了成年蛾的快速迁移外，幼虫的集体觅食行为也被认为与寻找新的食物来源有关，并极大地促进了受害地区的扩大。但是，化学信号是否以及如何参与该过程仍然未知。在这项研究中，成功​​地克隆了两种幼虫特异性表达的增香剂LstiOR5和LstiOR6。对非洲爪蟾卵母细胞的异源研究表明，几种寄主植物挥发物可以剂量依赖的方式引起LstiOR反应。一种草食动物诱导的大豆叶植物挥发物（HIPV），水杨酸甲酯（MeSA），在所有测试浓度下，对立式乳杆菌的幼虫均具有诱人的作用。进一步的觅食选择试验表明，L。sticticalis幼虫比未觅食的叶片更喜欢觅食的大豆叶片。当将MeSA人工添加到未觅食的叶子时，未觅食的叶子比觅食的叶子更可取。此外，GC-MS分析表明，MeSA是由幼虫的觅食行为诱导的，并在僵硬线虫中充当集体食物信号。此外，原位杂交表明LstiOR5在幼虫触角神经元中高表达。当LstiOR5沉默时，天线对MeSA的电生理响应和对觅食叶片的偏爱都大大降低，这表明LstiOR5参与了L.sticticalis的集体觅食行为。我们的研究结果阐明了化学信号触发了L. ticticis的集体觅食行为，并为在外围嗅觉水平上其受侵害区域扩展的分子机制提供了更多证据。这些发现可以促进控制该害虫的潜在控制策略的发展，并提供与潜在的L. ticticis集体觅食行为相关的潜在基因靶标，这可能导致更好的害虫管理。