Gaffke Alexander M, Sing Sharlene E, Millar Jocelyn G, Dudley Tom L, Bean Daniel W, Peterson Robert K D, Weaver David K
Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT.
Agricultural Research Service, Department of Agriculture, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL.
Environ Entomol. 2020 Oct 17;49(5):1063-1070. doi: 10.1093/ee/nvaa079.
The leaf beetle Diorhabda carinulata Desbrochers (Coleoptera: Chrysomelidae) was introduced into the United States in 1999 for classical biological control of the exotic woody invader saltcedar (Tamarix spp. L. [Caryophyllales: Tamaricaceae]). The recent southern expansion of the range of D. carinulata in the United States has precipitated conflict between proponents of biological control of Tamarix and those with concerns over habitat conservation for avian species. Several semiochemicals that mediate aggregations by this species have been reported, but no repellent compounds have been recorded thus far. We now report a repellent compound, 4-oxo-(E)-2-hexenal, induced by adult D. carinulata feeding on saltcedar foliage. Collection of headspace volatiles, gas chromatography mass spectrometry, and electroantennographic analyses identified 4-oxo-(E)-2-hexenal as an insect-induced compound that is antennally active. Behavioral and exposure assays were conducted to test for repellency and toxicity in adults and larvae. Headspace volatiles were also collected from adult males exposed to 4-oxo-(E)-2-hexenal to determine the impact exposure might have on the emission of the aggregation pheromone. 4-Oxo-(E)-2-hexenal elicited electrophysiological responses in adults of both sexes. Behavioral responses indicated repellency across multiple doses for reproductive D. carinulata adults but not in nonreproductive adults. Exposure assays indicated altered behaviors in first instar larvae and adults, but not in third instar larvae. Collection of headspace volatiles indicated that exposure to 4-oxo-(E)-2-hexenal did not alter emission of the D. carinulata aggregation pheromone by adult males. The continued development and field deployment of this repellent compound may provide a new tool for the management of D. carinulata.
叶甲Diorhabda carinulata Desbrochers（鞘翅目：叶甲科）于1999年被引入美国，用于对入侵的外来木本植物柽柳（Tamarix spp. L. [石竹目：柽柳科]）进行经典生物防治。最近，D. carinulata在美国分布范围的向南扩展引发了柽柳生物防治支持者与担心鸟类栖息地保护者之间的冲突。已有报道称该物种能介导聚集的几种信息化学物质，但迄今为止尚未记录到驱避化合物。我们现在报告一种由取食柽柳叶的D. carinulata成虫诱导产生的驱避化合物4-氧代-（E）-2-己烯醛。通过顶空挥发物收集、气相色谱-质谱联用以及触角电位分析，确定4-氧代-（E）-2-己烯醛是一种昆虫诱导产生的、具有触角活性的化合物。进行了行为和暴露试验，以测试其对成虫和幼虫的驱避性和毒性。还从暴露于4-氧代-（E）-2-己烯醛的成年雄性个体中收集顶空挥发物，以确定暴露可能对聚集信息素的释放产生的影响。4-氧代-（E）-2-己烯醛在两性成虫中引发了电生理反应。行为反应表明，对于繁殖期的D. carinulata成虫，该化合物在多个剂量下均表现出驱避性，但对非繁殖期成虫则无此作用。暴露试验表明，该化合物会使一龄幼虫和成虫的行为发生改变，但对三龄幼虫无此影响。顶空挥发物收集表明，暴露于4-氧代-（E）-2-己烯醛不会改变成年雄性个体释放D. carinulata聚集信息素的情况。这种驱避化合物的持续研发和田间应用可能为D. carinulata的管理提供一种新工具。
