Herbivorous insects assess and choose their potential host plants based on traits that may correlate with host suitability or quality. These traits may operate as cues for better resources, noxious chemicals, or fewer competitors and enemies. Interactions between insects and their host plants may also be modulated by the nutritional value of the plant, by plant chemical stimuli, or by physical traits such as trichomes. Differences in chemical or physical cues among plants may convey information about diet suitability. Several studies have addressed the topic of differences in plant traits between host and non-host plants; fewer have addressed these differences among potential host plants. We have studied the effect of chemical and physical plant traits on the feeding and oviposition preferences of the oligophagous herbivore Epilachna paenulata (Coleoptera: Coccinellidae) and two of its host plants, Cucurbita maxima and Cucurbita moschata (Cucurbitaceae). We first typified the volatile and non-volatile chemical profiles and the trichome distribution of the plants. Then, using behavioral assays, we evaluated feeding and oviposition preferences of E. paenulata. Further, to assess a correlation between oviposition preferences and offspring survival, we measured larval performance as indicated by survival, mass, and time to complete each instar. Female longevity in both Cucurbita host plants was also evaluated. Our results show that the congeneric plants bear differences in their chemical profiles, including volatile organic compounds, leaf waxes, and leaf parenchyma metabolites. Trichome abundance was also different, with C. maxima presenting fewer hairs. Epilachna paenulata females laid significantly more eggs in C. maxima, regardless of the plant they were raised as larvae. Female longevity on C. maxima was higher, but larval performance showed no difference between both plants. The proximate causes mediating female oviposition preferences may then involve trichome abundance, oviposition deterrents, toxic substances, or a combination of these factors.

草食昆虫根据可能与寄主适宜性或质量相关的性状评估和选择潜在的寄主植物。这些特征可能会成为获得更好的资源、有毒化学物质或更少的竞争对手和敌人的线索。昆虫与其寄主植物之间的相互作用也可能受到植物的营养价值、植物化学刺激或物理性状（如毛状体）的调节。植物之间化学或物理线索的差异可能传达有关饮食适宜性的信息。一些研究已经探讨了寄主植物和非寄主植物之间植物性状差异的主题；很少有人解决了潜在寄主植物之间的这些差异。我们研究了植物的化学和物理性状对寡食草食动物的取食和产卵偏好的影响Epilachna paenulata（鞘翅目：瓢虫科）及其两种寄主植物：Cucurbita maxima和Cucurbita moschata（葫芦科）。我们首先表征了植物的挥发性和非挥发性化学特征以及毛状体分布。然后，通过行为分析，我们评估了E. paenulata的摄食和产卵偏好。此外，为了评估产卵偏好和后代存活率之间的相关性，我们测量了幼虫的表现，如存活率、质量和完成每个龄期的时间。葫芦科女性长寿还对寄主植物进行了评估。我们的结果表明，同属植物的化学特征存在差异，包括挥发性有机化合物、叶蜡和叶薄壁组织代谢物。毛状体丰度也不同，其中毛状体的毛发较少。Epilachna paenulata雌性在C. maxima中产下明显更多的卵，无论它们是作为幼虫饲养的植物。C. maxima的雌性寿命较长，但两种植物之间的幼虫表现没有差异。调节雌性产卵偏好的直接原因可能涉及毛状体丰度、产卵阻碍、有毒物质或这些因素的组合。