Doctor of Philosophy
Date of Defense
Aimee Dunlap, PhD
Colorful floral signaling and resulting insect foraging behaviors have only been extensively examined in hymenopteran pollinators, especially bees, in comparison to flies, beetles, and butterflies regardless of their ecological importance. Therefore, my study provides novel information by focusing on foraging behaviors of adult passionflower butterflies, Heliconius melpomene and Dryas iulia, to the color changing flowers of Lantana camara. My dissertation which is divided into four chapters, aims to explore various aspects of color mediate foraging in passionflower butterflies by combining observations in the wild with controlled field and laboratory experiments. In the first chapter I reviewed flower color development and pollinators' sensory mechanisms to detect color changes to first elucidate the evolution of communication tactics from the senders (plants), and the detection mechanisms used by receivers (pollinators). In the second chapter I examined the relationship between sexual and foraging color biases of butterflies. In my third chapter I determined how color change associated with reward differences affected pollinator-plant attraction; and for my final chapter I investigated foraging movement patterns as butterflies fed on L. camara plants in their natural habitat. Overall, I presented evidence that indicated the following: 1) L. camara evolved a generalized pollination visitation system based on honest signaling―of reward quantity and quality tied to color changing visual signals acting in consort to produce a billboard effect that was easily perceived and deciphered by both passionflower butterflies; 2) experienced butterflies fed at flowers and were attracted to inflorescences that were of similar color to their wings, however, newly emerged butterflies exhibited different but species specific behaviors; 3) foraging behaviors were subject to change based on light environment, with yellow flower color eliciting feeding responses under blue light (open sky), and red elicited foraging under green light conditions (under forest canopy); 4) butterflies partitioned food resources spatially and temporally from each other, and from aggressive territorial hummingbirds; and 5) butterfly species changed the number of visits to plants, number of plants visited, and time spent foraging in order to successfully coexist with heterospecific competitors that shared the same space and food resource.
Maharaj, Gyanpriya, "Color-mediated foraging by pollinators: A comparative study of two passionflower butterflies at Lantana camara" (2016). Dissertations. 42.