Larval frass in herbivorous lepidopterans is mainly composed of plant-derived material and microbes from the gut. Despite the fact that frass from conspecific larvae repels female moths in Spodoptera littoralis from oviposition, the role of frass volatiles on larval foraging behavior is largely unknown. Here, we show that larvae of S. littoralis walk upwind to larval frass volatiles in a wind tunnel assay. We identified the frass volatile guaiacol (2-methoxyphenol) as key ligand for the S. littoralis odorant receptor (OR) SlitOr59 which we expressed heterologously. We isolated guaiacol-producing bacteria identified as Serratia marcescens from frass of larvae that were fed on cotton, and Enterobacter cloacae, E. ludwigii and Klebsiella sp. from frass derived from cabbage-fed larvae. In addition to guaiacol, we also identified volatiles acetoin, 3-methyl-1-butanol and dimethyl disulfide, in large proportions in headspace collections from the bacteria. A Y-tube olfactometer assay showed that fourth instar S. littoralis larvae are attracted to guaiacol. Moreover, cotton leaves treated with the insecticide Spinosad and guaiacol were highly attractive to the larvae. Our results provide a basis for management of the pest by directly targeting larvae, based on an attract-and-kill strategy. Further studies are needed to test the application of guaiacol for semiochemical-based pest management of Spodoptera pest species.

草食性鳞翅类动物的幼虫主要由植物来源的材料和肠道微生物组成。尽管来自特定种的幼虫的ass驱赶了产卵夜蛾的雌蛾，但鲜为人知的是，ass挥发物对幼虫觅食行为的作用是未知的。在这里，我们表现出的幼虫S.沙参步行逆风以幼虫虫粪挥发物在风洞试验。我们确定了fras挥发性愈创木酚（2-甲氧基苯酚）是我们异源表达的S. littoralis气味受体（OR）Slit Or59的关键配体。我们从以棉为食的幼虫中分离出了被鉴定为粘质沙雷氏菌的产生愈创木酚的细菌，并阴沟肠杆菌，路德维希大肠杆菌和克雷伯菌属。来自从白菜喂养的幼虫中提取的苦菜。除愈创木酚外，我们还从细菌的顶空收集物中鉴定出了大部分的挥发物丙酮酸，3-甲基-1-丁醇和二甲基二硫化物。Y-管嗅觉测定法表明，第四龄的滨海链球菌幼虫被愈创木酚吸引。此外，用杀虫剂Spinosad和愈创木酚处理过的棉叶对幼虫具有高度的吸引力。我们的研究结果为基于吸引和杀死策略的直接针对幼虫的有害生物治理提供了基础。需要进一步的研究来测试愈创木酚在基于化学信息的食斜纹夜蛾有害生物管理中的应用。