Date of Award


Degree Type


Degree Name

Master of Science (MS)




David Althoff


Chemical Ecology, Floral Chemistry, Floral Scent, Phytochemistry, Plant-Pollinator Interactions, Tissue-Specific Floral Scent


Abstract: Interactions between plants and insect pollinators are of critical importance as the majority of flowering plants rely on animals for pollination and insects are the most diverse group of pollinators on Earth. To obtain pollination services plants must attract pollinators by signaling the presence of rewards, and chemosensory cues including floral scent are of particular importance to pollinator attraction. In highly-specialized brood-pollination mutualisms, like the yucca-yucca moth mutualism, the “reward” for pollinators is a brood site and food source for their offspring: fertilized plant ovules. Being able to distinguish among floral parts is critical for yucca moths to successfully execute the complex behaviors required for oviposition and pollination. Fine-scale, tissue-specific patterns of floral scent potentially play an important role in helping pollinators to navigate toward rewards, but such patterns and their ecological consequences remain poorly understood. To address this, I examined the floral scent of the tepals and pistils of five species of Yucca. All five species of Yucca had tissue-specific patterns of scent emission. Tissue-specific patterns of floral scent also varied among Yucca species, with two species Y. reverchonii and Y. rupicola producing low to nonexistent levels of a subset of compounds of known biological relevance to pollinating moths. I also observed a trend in the oviposition behavior of the common pollinator of these five species (Tegeticula yuccasella), wherein moths oviposited at higher rates in chemically similar yuccas and at lower rates in yuccas with reduced (or no) expression of known, biologically relevant compounds. Even though there is variation in the scent profile of tepals and pistils across Yucca species, T. yuccasella successfully uses all hosts in the wild. Our results show that moths may be using a broader, potentially redundant suite of compounds to identify yuccas and their specific tissues rather than relying on a few major compounds to determine host suitability.


Open Access



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