Differential olfactory responses associated with host plant shift by the fruit-piercing moth, Eudocima phalonia, in the Pacific islands

The fruit-piercing moth (FPM) Eudocima phalonia is widely present in the tropics, causing major damages to the citrus industry. In its ancestral distribution range, e.g. Australia, FPM develops on vines from the Menispermaceae family. But in more recently colonized islands, e.g. New Caledonia, FPM populations have shifted to new host plants of the Fabaceae family, Erythrina spp.. To understand this host shift, we studied the chemical ecology of FPM as a mechanism driving host plant acceptance. We collected volatile headspace samples of Erythrina species and Menispermaceae and compared their chemical spectra. We assessed the electrophysiological responses of FPM populations from the two countries to the plant chemical extracts and identified bioactive compounds. The volatile profiles from each species were quite different between and within each plant family. However, five compounds common across the two families triggered electrophysiological responses in both FPM populations. Those common bioactive compounds could have facilitated the host shift to completely different plant family. Furthermore, the diverging history between the two FPM populations may explain differences in electrophysiological sensitivity to other specific compounds. These results are discussed in the context of the production of a generic lure that could be attractive to all FPM populations.蛀果蛾（fruit-piercing moth, FPM）Eudocima phalonia广泛分布于热带区域，对柑橘产业造成重大经济损失。在其原生分布范围（如澳大利亚），该蛀果蛾以防己科（Menispermaceae）植物藤本为寄主。但在新近定殖的岛屿（如新喀里多尼亚），蛀果蛾种群已转换至豆科（Fabaceae）刺桐属（Erythrina spp.）的新寄主植物。为解析这一寄主转换现象，本研究围绕调控蛀果蛾寄主接受行为的化学生态机制开展探究。我们采集了刺桐属植物与防己科植物的挥发性顶空样品，对比二者的化学谱图特征；检测了来自两个地区的蛀果蛾种群对植物化学提取物的电生理反应，并鉴定出具有生物活性的化合物。各植物类群内部及类群间的挥发性成分谱存在显著差异。然而，两个科植物共有的五种化合物均可在两种蛀果蛾种群中引发电生理反应。这类共有生物活性化合物或推动了蛀果蛾向完全不同的植物科寄主完成转换。此外，两个蛀果蛾种群的分化历史，可解释二者对其他特定化合物的电生理敏感性差异。本研究结果将结合可吸引所有蛀果蛾种群的通用诱剂开发这一应用场景展开讨论。