Department of Entomology, University of Wisconsin-Madison, Madison, WI, United States.
Department of Biology, University of Wisconsin-Oshkosh, Oshkosh, WI, United States.
J Evol Biol. 2024 Jan 29;37(1):62-75. doi: 10.1093/jeb/voad004.
Associating with plant hosts is thought to have elevated the diversification of insect herbivores, which comprise the majority of global species diversity. In particular, there is considerable interest in understanding the genetic changes that allow host-plant shifts to occur in pest insects and in determining what aspects of functional genomic diversity impact host-plant breadth. Insect chemoreceptors play a central role in mediating insect-plant interactions, as they directly influence plant detection and sensory stimuli during feeding. Although chemosensory genes evolve rapidly, it is unclear how they evolve in response to host shifts and host specialization. We investigate whether selection at chemosensory genes is linked to host-plant expansion from the buffalo burr, Solanum rostratum, to potato, Solanum tuberosum, in the super-pest Colorado potato beetle (CPB), Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). First, to refine our knowledge of CPB chemosensory genes, we developed novel gene expression data for the antennae and maxillary-labial palps. We then examine patterns of selection at these loci within CPB, as well as compare whether rates of selection vary with respect to 9 closely related, non-pest Leptinotarsa species that vary in diet breadth. We find that rates of positive selection on olfactory receptors are higher in host-plant generalists, and this signal is particularly strong in CPB. These results provide strong candidates for further research on the genetic basis of variation in insect chemosensory performance and novel targets for pest control of a notorious super-pest.
与植物宿主的关联被认为提高了昆虫食草动物的多样化程度，而昆虫食草动物构成了全球物种多样性的大部分。特别是，人们非常感兴趣的是了解允许害虫昆虫发生宿主植物转移的遗传变化，并确定功能基因组多样性的哪些方面影响宿主植物的广度。昆虫化感器在介导昆虫-植物相互作用中起着核心作用，因为它们直接影响进食期间植物的检测和感官刺激。尽管化学感受基因进化迅速，但尚不清楚它们如何响应宿主转移和宿主特化而进化。我们研究了在超级害虫科罗拉多马铃薯甲虫（CPB）Leptinotarsa decemlineata（鞘翅目：叶甲科）中，从水牛刺果到马铃薯的宿主植物扩张过程中，化学感受基因的选择是否与宿主有关。首先，为了完善我们对 CPB 化学感受基因的了解，我们开发了触角和上颌唇须的新基因表达数据。然后，我们检查了这些基因座在 CPB 内的选择模式，并比较了与饮食广度不同的 9 种密切相关的非害虫 Leptinotarsa 物种的选择率是否有所不同。我们发现，在宿主植物的泛化者中，嗅觉受体的正选择率更高，而在 CPB 中，这种信号尤其强烈。这些结果为进一步研究昆虫化学感受性能变化的遗传基础以及臭名昭著的超级害虫的害虫控制的新目标提供了强有力的候选者。
