Aphids are destructive pests, and alarm pheromones play a key role in their chemical ecology. Here, we conducted a detailed analysis of terpenoids in the vetch aphid, Megoura viciae, and its host plant Pisum sativum using gas chromatography/mass spectrometry. Four major components, (-)-β-pinene (49.74%), (E)-β-farnesene (32.64%), (-)-α-pinene (9.42%) and ( +)-limonene (5.24%), along with trace amounts of ( +)-sabinene, camphene and α-terpineol) (3.14%) were found in the aphid. In contrast, few terpenoids were found in the host plant, consisting mainly of squalene (66.13%) and its analog 2,3-epoxysqualene (31.59%). Quantitative analysis of the four major terpenes in different developmental stages of the aphid showed that amounts of the monoterpenes increased with increasing stage, while the sesquiterpene amount peaked in the 3^rd instar. (-)-β-Pinene was the most abundant terpene at all developmental stages. Behavioral assays using a three-compartment olfactometer revealed that the repellency of single compounds varied in a concentration-dependent manner, but two mixtures [(-)-α-pinene: (-)-β-pinene: (E)-β-farnesene: ( +)-limonene = 1:44.4:6.5:2.2 or 1:18.4:1.3:0.8], were repellent at all concentrations tested. Our results suggest that (-)-α-pinene and (-)-β-pinene are the major active components of the alarm pheromone of M. viciae, but that mixtures play a key role in the alarm response. Our study contributes to the understanding of the chemical ecology of aphids and may help design new control strategies against this aphid pest.

Graphical abstract

中文翻译：

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野豌豆蚜虫报警信息素的鉴定及行为分析

蚜虫是破坏性害虫，警报信息素在其化学生态中起着关键作用。在这里，我们使用气相色谱/质谱法对野豌豆蚜虫Megoura viciae及其寄主植物豌豆中的萜类化合物进行了详细分析。四种主要成分，(-)-β-蒎烯 (49.74%)，( E)-β-法呢烯 (32.64%)、(-)-α-蒎烯 (9.42%) 和 (+)-柠檬烯 (5.24%)，以及微量的 (+)-蒎烯、莰烯和α-萜品醇）（ 3.14%) 在蚜虫中发现。相比之下，寄主植物中发现的萜类化合物很少，主要由角鲨烯 (66.13%) 及其类似物 2,3-环氧角鲨烯 (31.59%) 组成。在蚜虫的不同发育阶段的四大萜烯的定量分析表明，单萜量的增加而增加阶段，而倍半萜烯量在3见顶^第三龄。(-)-β-Pinene 是所有发育阶段最丰富的萜烯。使用三室嗅觉计的行为分析表明，单一化合物的排斥性以浓度依赖性方式变化，但两种混合物 [(-)-α-蒎烯：(-)-β-蒎烯：(E )-β-法呢烯：( +)-柠檬烯 = 1:44.4:6.5:2.2 或 1:18.4:1.3:0.8]，在所有测试浓度下均具有驱避性。我们的研究结果表明，(-)-α-蒎烯和 (-)-β-蒎烯是M. viciae警报信息素的主要活性成分，但混合物在警报响应中起关键作用。我们的研究有助于了解蚜虫的化学生态学，并可能有助于设计针对这种蚜虫害虫的新控制策略。

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