Doctor of Philosophy
Date of Defense
Robert J. Marquis
Aimee S. Dunlap
Elizabeth A. Kellogg
Robert E. Ricklefs
Thousands of Lepidoptera species build shelters as caterpillars using plant material and their own silk. Although these caterpillars and their shelters are recognized as playing important ecological roles, the structural diversity of shelters and the costs and benefits of different shelters to their builders are still poorly understood. In this dissertation, I use natural history observations, observational and manipulative field projects, and molecular and phylogenetic tools to investigate these questions for a diverse and abundant shelter-building caterpillar community within the dry forest of Palo Verde National Park, Costa Rica. In Chapter 1, I develop a system for categorizing and describing the structural diversity of caterpillar shelters and apply it to the 95 shelter-building species I encountered during five field seasons. When analyzed this way, it becomes apparent that certain shelter types and traits are more common in this community than others, and that some shelters are associated with particular lepidopteran families. In Chapter 2, I describe the unique shelter-building behavior of a caterpillar species (Aristotelia corallina: Gelechiidae) living on ant-defended acacias. I also use caterpillar shelters preserved on herbarium specimens to propose host plant and geographic ranges for members of the A. corallina species complex. Caterpillar shelters are frequently preserved in herbarium collections and represent an under-used resource for identifying plant-insect interactions. In Chapter 3, I disentangle the effects of shelter shape and caterpillar identity on predation and parasitism by placing Urbanus dorantes and Urbanus proteus caterpillars (Hesperiidae) in both species’ shelters. This experiment demonstrates that shelter shape has a significant effect on predation, and possibly parasitism, independent of caterpillar species identity. In Chapter 4, I explore shelter traits, predation, and parasitism in a phylogenetic context for a subset of species. I demonstrate that phylogeny significantly predicts shelter traits, that both phylogeny and shelter traits significantly affect predation, and that parasitism is negatively correlated with predation. This provides strong support for the hypothesis that parasitoids target caterpillar species which are less likely to be killed by predators. Overall, this work demonstrates that caterpillar shelters can provide important insights into taxonomic and phylogenetic relationships, ecological interactions, and evolutionary pressures.
Baer, Christina, "The Diversity, Costs, and Benefits of Shelters Built by Lepidopteran Caterpillars in a Costa Rican Dry Forest" (2017). Dissertations. 704.
Additional FilesBaer-A corallina Video1.mp4 (72999 kB)
Aristotelia corallina caterpillar consuming a Beltian body in the laboratory.
Baer-A corallina Video2.MOV (241628 kB)
Prepupal Aristotelia corallina caterpillar using silk to cover a domatium’s entrance hole.
Baer-A corallina Video3.wmv (28564 kB)
A complete Aristotelia corallina shelter-building session on Vachellia collinsii foliage. Video at eight times normal speed.