Kursar Thomas A, Wolfe Brett T, Epps Mary Jane, Coley Phyllis D
Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
Ecology. 2006 Dec;87(12):3058-69. doi: 10.1890/0012-9658(2006)87[3058:fqcapi]2.0.co;2.
We surveyed Lepidoptera found on 11 species of Inga (Fabaceae:Mimosoideae) co-existing on Barro Colorado Island, Panama, to evaluate factors influencing diet choice. Of the 47 species of caterpillars (747 individuals) recorded, each fed on a distinct set of Inga. In the field, 96% of the individuals were found on young leaves. Growth rates of caterpillars that were fed leaves in the laboratory were 60% higher on young leaves compared to mature leaves. When caterpillars were fed leaves of nonhost Inga, they grew more slowly. These data provide support for a link between preference and performance. However, among hosts on which larvae normally occurred, faster growth rates were not associated with greater host electivity (the proportion of larvae found on each host species in the field, corrected for host abundance). Growth rates on normal hosts were positively correlated with leaf expansion rates of the host, and fast expansion was associated with leaves with higher nutritional content. Detailed studies on a gelechiid leaf roller, the species with the largest diet breadth, allowed us to assess the importance of factors other than growth that could influence diet electivity. This species showed a 1.7-fold difference in growth rate among Inga hosts and faster growth on species with fast-expanding leaves. However, there was no correlation between caterpillar growth rate and abundance on different host species. Instead, abundance of the gelechiid on each Inga species was significantly correlated with the temporal predictability of food (synchrony of leaf flushing) and was negatively correlated with competition (amount of leaf area removed by species other than the gelechiid). Although rates of parasitism were high (23-43%), there were no differences among hosts. Parasitism was also not related to measures of escape, such as growth rates of caterpillars, leaf expansion rates, and synchrony of leaf production. Together, food availability, parasitism, and competition explained 84% of the variation in host preference by the gelechiid. We suggest that these ecological interactions may be particularly important in determining diet choice initially and that preferences may be reinforced by subsequent divergence in host chemistry and/or the herbivore's ability to tolerate the secondary metabolites.
我们调查了巴拿马巴罗科罗拉多岛上共存的11种油楠属植物（豆科：含羞草亚科）上发现的鳞翅目昆虫，以评估影响食性选择的因素。在记录的47种毛虫（747只个体）中，每种毛虫都以一组独特的油楠属植物为食。在野外，96%的个体出现在嫩叶上。在实验室中，以嫩叶喂养的毛虫的生长速度比以成熟叶喂养的毛虫高60%。当毛虫以非寄主油楠属植物的叶子为食时，它们生长得更慢。这些数据为偏好与生长表现之间的联系提供了支持。然而，在幼虫通常出现的寄主中，较快的生长速度与更高的寄主选择性（野外在每种寄主物种上发现的幼虫比例，根据寄主丰度进行校正）并无关联。在正常寄主上的生长速度与寄主的叶片扩展速度呈正相关，快速扩展与营养成分较高的叶片相关。对食性范围最广的谷蛾科卷叶蛾物种进行的详细研究，使我们能够评估除生长之外可能影响食性选择的其他因素的重要性。该物种在油楠属寄主间的生长速度有1.7倍的差异，在叶片快速扩展的物种上生长得更快。然而，毛虫的生长速度与在不同寄主物种上的数量并无关联。相反，谷蛾科卷叶蛾在每种油楠属植物上的数量与食物的时间可预测性（叶片萌发的同步性）显著相关，与竞争（谷蛾科卷叶蛾以外的物种去除的叶面积量）呈负相关。尽管寄生率很高（23%-43%），但寄主之间并无差异。寄生也与逃避措施无关，如毛虫的生长速度、叶片扩展速度和叶片产生的同步性。食物可利用性、寄生和竞争共同解释了谷蛾科卷叶蛾寄主偏好变异的84%。我们认为，这些生态相互作用在最初决定食性选择时可能特别重要，并且偏好可能会因寄主化学物质的后续差异和/或食草动物耐受次生代谢物的能力而得到加强。
