DISSERTATION RESEARCH: Costs and Benefits of Shelter-Building by Lepidopteran Caterpillars in a Tropical Dry Forest

数以万计的毛毛虫物种用丝绸和树叶建造庇护所。许多种类丰富，是重要的森林害虫。然而，关于避难所如何影响毛毛虫的生存以及最终影响它们成年后的产卵，人们知之甚少。该项目将提供有关收容所对毛毛虫生存和成虫成功的影响的信息。首先，该项目测试了避难所对高温和低湿度的保护程度。这些信息将有助于确定毛毛虫对环境的敏感程度，澄清当地和全球气候的变化可能如何影响建造避难所的物种的成功。其次，该项目将测试庇护所对捕食性昆虫和蜘蛛以及寄生蜂和苍蝇的保护效果。具体地说，这些实验将确定毛虫的庇护所是否对捕食者提供了更好的保护，是否更容易受到寄生昆虫的攻击。捕食者和寄生昆虫都是用来控制害虫的，因此检验这一假说可以应用于害虫管理。由于研究地点在哥斯达黎加，研究人员还将提高人们对未被研究的热带栖息地(热带干燥森林)的认识，并促进国际联系和培训。研究人员将利用合作建立集体庇护所的毛虫物种进行两组实验，其中可能会发现两到十只毛毛虫生活在一起。这两组实验都将在毛毛虫的天然森林栖息地进行。第一个实验将测量庇护所和环境对四种毛虫存活的影响。毛毛虫以及温度和湿度传感器将被放置在毛毛虫庇护所内外。将监测毛毛虫的存活情况，以确定毛毛虫是否通过它们的庇护所保护免受外部环境的影响。第二个实验将衡量为两种毛毛虫建立和共享集体庇护所的成本和收益。毛毛虫将被允许单独或成群建造庇护所，并将测量捕食者和寄生虫造成的死亡率。如果一些治疗方法不太可能被捕食者杀死，研究人员将测试这些毛虫是否也更有可能受到寄生昆虫的攻击。与其他毛毛虫共用一个庇护所的积极和消极影响也将通过称重存活的毛毛虫的幼虫来衡量。较重的幼虫变成成虫后通常会产生更多的后代，因此这一措施将允许研究人员确定共用一个庇护所是有负面影响(由于与其他毛毛虫竞争)还是积极影响(由于分担建造和维护庇护所的成本)。

Tens of thousands of caterpillar species build shelters out of silk and leaves. Many are sufficiently abundant that they are important forest pests. However, little is known about how shelters affect the survival of the caterpillars and ultimately their egg production as adults. This project will provide information on the impact that shelters have on caterpillar survival and adult success. First, the project tests how much protection shelters provide from high temperatures and low humidity. This information will help determine how sensitive the caterpillars are to their environment, clarifying how changes in local and global climate might influence the success of shelter-building species. Second, the project will test the protective effects of shelters against predatory insects and spiders, and against parasitic wasps and flies. Specifically, the experiments will determine whether caterpillars whose shelters provide better protection against predators are more vulnerable to parasitic insects. Both predators and parasitic insects are used to control pest insects, so testing this hypothesis could be applied to pest management. Because the research site is in Costa Rica, the researchers will also increase awareness of an under-studied tropical habitat (tropical dry forests) and foster international connections and training.The researchers will perform two sets of experiments using caterpillar species that cooperatively build group shelters, in which two to ten caterpillars can be found living together. Both sets of experiments will be conducted in the natural forest habitat of the caterpillars. The first experiment will measure the effects of shelters and the environment on caterpillar survival for four species. Caterpillars, along with temperature and humidity sensors, will be placed both inside and outside caterpillar shelters. Caterpillar survival will be monitored to determine whether the caterpillars are protected from the outside environment by their shelters. The second experiment will measure the costs and benefits of building and sharing group shelters for two caterpillar species. Caterpillars will be allowed to build shelters either alone or in groups, and the mortality caused by predators and parasitic insects will be measured. If some treatments are less likely to be killed by predators, the researchers will test whether the caterpillars are also more likely to be attacked by parasitic insects. The positive and negative effects of sharing a shelter with other caterpillars will also be measured by weighing the pupae of surviving caterpillars. Heavier pupae become adults who generally produce more offspring, so this measure will allow the researchers to determine whether sharing a shelter has a negative effect (due to competition with other caterpillars) or a positive one (due to sharing the costs of building and maintaining the shelter).