Understanding the simultaneous effects of selection by mutualists and antagonists on the evolution of floral characters remains a challenge to evolutionary ecologists. Floral fragrance advertises reproductive structures to promote pollination. Detrimental insects, however, are navigating within the same scent landscape as pollinators. If the same scent components attract both mutualists and antagonists, evolution of fragrance may be constrained by opposing selection pressures. Whereas animals are known to reduce sexual display traits when there is risk of predation, floral traits have rarely been considered with regard to detrimental insects. The PI will evaluate the fitness effects of variation in floral fragrance of Texas gourd (Cucurbita pepo subsp. Texana) in the presence and absence of herbivores. Moreover, the PI will establish fragrance preference in pollinators and herbivores and conduct a manipulative study to determine the effect of beetle damage on fragrance production. Ultimately the PI will measure the costs associated with a trait that attracts pollinators but also attracts detrimental insects, costs that could result in diminishing returns with regard to fitness.
Broader impacts: Active pollination is necessary for fruit production in squash. While research has focused on pest control, less attention has been paid to the importance of pollination. Both pollinators and the beetles that feed on squash are attracted and guided to the squash flower by its fragrance. Nevertheless, crop varieties have been bred with little regard to fragrance emission. Recent efforts, however, aim to enhance natural pollination by identifying more fragrant varieties of squash. The researchers will study the fitness benefits and potential disadvantages of enhanced fragrance, providing data for increasing crop yield. Undergraduate minority and women students will be encouraged to join the research effort and work independently on projects. Students will be trained in field methods and analytical chemistry, giving them a broad set of tools and insight into experimental design and analysis. In addition, information on the biology and abundances of local insect populations will be exchanged with local farmers as well as contribute to a multinational study of squash bee abundance patterns.