Sorensen Mary A, Bethke James A, Redak Richard A
Department of Entomology, University of California, Riverside, CA 92521, USA.
Environ Entomol. 2010 Feb;39(1):159-63. doi: 10.1603/EN09086.
Although larvae and adults of the herbivorous beetle Trirhabda geminata Horn (Coleoptera: Chrysomelidae) are primarily considered to be specialists on Encelia farinosa (Compositae: Asteraceae), some reports exist of these beetles feeding on related Encelia species. Within the genus Encelia, many species are thought to have evolved relatively recently. In addition, some Encelia species have very similar secondary chemistries and overlapping geographic distributions. In the laboratory, individual T. geminata were reared on E. farinosa or the sympatrically occurring species E. actoni or E. californica. Survival, growth, and development were analyzed for larvae feeding on each host plant species. Overall, herbivore performance was better on E. farinosa, with significantly greater survival, faster development, and greater mass gain. Beetle development on E. californica was intermediate, with some measure, indicating better performance than on E. actoni and other measure, indicating no difference between these potential hosts. Importantly, although performance was decreased on E. actoni and E. californica, some individuals were able to develop successfully, suggesting that populations of T. geminata may be able to adapt to use these host plants.
尽管食草甲虫Trirhabda geminata Horn（鞘翅目：叶甲科）的幼虫和成虫主要被认为是粉苞菊（菊科：菊苣族）的专食性昆虫，但也有一些关于这些甲虫取食粉苞菊属相关物种的报道。在粉苞菊属内，许多物种被认为是相对较近才进化出来的。此外，一些粉苞菊属物种具有非常相似的次生化学物质和重叠的地理分布。在实验室中，将单个的Trirhabda geminata饲养在粉苞菊、同域分布的阿克托尼粉苞菊或加州粉苞菊上。分析了取食每种寄主植物的幼虫的存活、生长和发育情况。总体而言，食草动物在粉苞菊上的表现更好，存活率显著更高、发育更快且体重增加更多。甲虫在加州粉苞菊上的发育处于中等水平，在某些指标上，表明其表现优于在阿克托尼粉苞菊上；而在其他指标上，则表明这两种潜在寄主之间没有差异。重要的是，尽管在阿克托尼粉苞菊和加州粉苞菊上表现有所下降，但仍有一些个体能够成功发育，这表明Trirhabda geminata种群可能能够适应利用这些寄主植物。
