Plant Influences on Parasitism of Two Leafminers: A Test of Enemy‐Free Space
Plant Influences on Parasitism of Two Leafminers: A Test of Enemy‐Free Space
复制标题
植物对两种潜叶蝇寄生的影响：无敌空间测试
作者：
P. Gross;P. Price
我们评估了寄主植物性状的重要性，作为一个更大的寄生蜂物种丰富度的原因，Tildenia inscarcuella（鳞翅目：麦蛾科），一个在horsenettle，Solanum carolinense上的潜叶虫，比Tildenia georgei，一个在地面樱桃上的潜叶虫，酸浆变种。模棱两可。在三个田间试验中，我们没有发现寄主植物对寄生蜂短期影响的证据。没有一种寄生蜂能成功地寄生转移到红腹潜蝇身上的地樱潜蝇。寄生率和寄生蜂种类的组成并没有不同的horsenettle矿工的horsenettle与茄子，也没有为地下樱桃矿工绑与untied叶。相反，寄主植物形态对潜叶蝇行为的长期影响解释了两种潜叶蝇寄生率的差异。而地雷的地雷结构的地下樱桃矿工允许幼虫离开其地雷和自由移动的叶片表面，马蜂窝矿工停留在其地雷，即使受到干扰。我们发现，这种差异使horsenettle矿工容易受到更多的寄生虫物种，它可以被利用，不仅寄生虫，可以攻击流浪的主机，但也被寄生虫限于隐蔽，久坐的主机。有证据进一步表明，通过选择不允许矿工容易接近叶表面的矿结构，马荨麻三染色体形态有利于马荨麻矿工中这种专性内生菌的进化。当实验放置在叶片表面时，矿工幼虫不能以马荨麻为食，因为它们不能穿透其星状毛状体的网状结构。在地面樱桃，那里的毛状体薄而灵活，幼虫很容易启动地雷。我们认为，专性内生，这是不常见的相关gelechiids，是一个特定的适应horsenettle形态，使horsenettle矿工提供给更多的寄生虫物种比它的流浪亲戚。
We evaluated the importance of host plant traits as causes for a much greater parasitoid species richness on Tildenia inconspicuella (Lepidoptera: Gelechiidae), a leaf- miner on horsenettle, Solanum carolinense, than on Tildenia georgei, a leafminer on ground- cherry, Physalis heterophylla var. ambigua. In three field experiments, we found no evidence for short-term effects of host plants on parasitoids. None of the parasitoid species normally associated with the horsenettle miner successfully parasitized groundcherry miners trans- ferred to horsenettle. Rates of parasitism and composition of parasitoid species did not differ for horsenettle miners on horsenettle vs. on eggplant, nor for groundcherry miners in tied vs. untied leaves. Instead, long-term effects of host plant morphology on leafminer behavior explained differences in parasitism between the two leafminer species. Whereas the mine structure of the groundcherry miner allows the larva to leave its mine and move freely over the leaf surface, the horsenettle miner stays within its mine, even when disturbed. We found that this difference has made the horsenettle miner vulnerable to more parasitoid species; it can be exploited, not only by parasitoids that can attack vagile hosts, but also by parasitoids restricted to concealed, sedentary hosts. Evidence further indicated that horsenettle tri- chome morphology has favored the evolution of this obligate endophytism in the horsenettle miner by selecting against mine architectures that would allow miners easy access to the leaf surface. When experimentally placed on leaf surfaces, miner larvae could not feed on horsenettle because they could not penetrate its meshwork of stellate trichomes. On ground- cherry, where trichomes are thin and flexible, larvae easily initiated mines. We argue that obligate endophytism, which is uncommon among related gelechiids, is a specific adaption to horsenettle morphology that has made the horsenettle miner available to more parasitoid species than its vagile relatives.