We explored how gut-associated yeasts influence olfactory behaviour and resource use in two pest species of Carpophilus beetle that co-exist in Australian stone fruits. Molecular analysis of yeasts isolated from the gut of C. davidsoni (prefers ripe fruits) and C. hemipterus (prefers overripe and rotting fruits) revealed that the predominant species were Pichia kluyveri and Hanseniaspora guilliermondii. In olfactory attraction and oviposition trials, adult beetles preferred H. guilliermondii over P. kluyveri, and follow up GC-MS analysis revealed unambiguous differences between the odour profiles of these yeasts. In contrast to behavioural trials, larval feeding assays showed that fruit substrates inoculated with P. kluyveri yielded significantly faster development times, higher pupal mass, and a greater number of adult beetles, compared to H. guilliermondii — in other words, the lesser preferred yeast (by foraging adults) was more suitable for larval survival. Moreover, whilst larvae of both species survived to adulthood when fed solely on P. kluyveri (i.e. without a fruit substrate), only larvae of C. davidsoni could develop on H. guilliermondii; and only C. davidsoni reached adulthood feeding on a yeast-free fruit substrate. We discuss how these findings may relate to adaptations towards early colonising of fruits by C. davidsoni, enabling differences in resource use and potentially resource partitioning in the two beetles. More broadly, consideration of microbial interactions might help develop host selection theory. Our results could pave the way to more powerful attractants to mass-trap and monitor Carpophilus pests in fruit orchards.

中文翻译：

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酵母影响两个食肉性嗜果甲虫物种的寄主选择和幼虫适应性。

我们探索了肠道相关酵母如何影响澳大利亚核果中共存的两种嗜果甲虫的嗅觉行为和资源利用。从肠道分离的酵母菌的分子分析C. davidsoni（喜欢成熟的水果）和C. hemipterus（喜欢熟和腐烂的果实）揭示的主要种类是克鲁维毕赤酵母和汉逊季也蒙。在嗅觉吸引力和产卵试验，成年甲虫优选H.季也蒙过P.克鲁，以及后续的GC-MS分析显示，这些酵母的气味之间没有明显差异。与行为试验相反，幼虫摄食试验表明，与古氏嗜血杆菌相比，接种克鲁维氏 酵母的水果基质可显着加快发育时间，增加up质量和成年甲虫数量，换句话说，首选酵母较少（通过觅食成虫）更适合幼虫生存。此外，虽然这两个物种的幼虫存活到成年当仅馈送P.克鲁弗（即，没有水果基板），只幼虫C. davidsoni可以在开发H.季也蒙; 和只有C. davidsoni到成年期以不含酵母的水果为食。我们讨论如何这些结果可能与改编朝着年初殖民水果C. davidsoni，实现资源利用的差异和潜在的资源在这两个甲虫分区。更广泛地讲，考虑微生物相互作用可能有助于发展宿主选择理论。我们的结果可以为更强大的引诱剂铺路，以诱捕和监测果园中的嗜果菌害虫。