Department of Animal and Plant Sciences, The University of Sheffield, Sheffield, S10 2TN, UK.
Sci Rep. 2017 Aug 17;7(1):8498. doi: 10.1038/s41598-017-07729-0.
The diversity of phytophagous insects is largely attributable to speciation involving shifts between host plants. These shifts are mediated by the close interaction between insects and plant metabolites. However, there has been limited progress in understanding the chemical signatures that underlie host preferences. We use the pea aphid (Acyrthosiphon pisum) to address this problem. Host-associated races of pea aphid discriminate between plant species in race-specific ways. We combined metabolomic profiling of multiple plant species with behavioural tests on two A. pisum races, to identify metabolites that explain variation in either acceptance or discrimination. Candidate compounds were identified using tandem mass spectrometry. Our results reveal a small number of compounds that explain a large proportion of variation in the differential acceptability of plants to A. pisum races. Two of these were identified as L-phenylalanine and L-tyrosine but it may be that metabolically-related compounds directly influence insect behaviour. The compounds implicated in differential acceptability were not related to the set correlated with general acceptability of plants to aphids, regardless of host race. Small changes in response to common metabolites may underlie host shifts. This study opens new opportunities for understanding the mechanistic basis of host discrimination and host shifts in insects.
植食性昆虫的多样性在很大程度上归因于涉及寄主植物之间转移的物种形成。这些转移是由昆虫和植物代谢物之间的密切相互作用介导的。然而，在理解决定寄主偏好的化学特征方面，进展有限。我们使用豌豆蚜（Acyrthosiphon pisum）来解决这个问题。与寄主相关的豌豆蚜以特定于种族的方式在植物物种之间进行区分。我们结合了多种植物物种的代谢组学分析以及两种 A. pisum 种族的行为测试，以确定解释接受或歧视变化的代谢物。使用串联质谱法鉴定候选化合物。我们的结果揭示了一小部分化合物，这些化合物解释了 A. pisum 种族对植物的可接受性差异的很大一部分变化。其中两种被鉴定为 L-苯丙氨酸和 L-酪氨酸，但可能是代谢相关的化合物直接影响昆虫的行为。与一般接受性相关的植物相关的化合物与差异可接受性没有关系，无论寄主种族如何。对常见代谢物的微小变化可能是寄主转移的基础。这项研究为理解昆虫寄主识别和寄主转移的机制基础开辟了新的机会。
