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Role of color and odor on the attraction of insect visitors to spring blooming trillium

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Natasha Marie Shipman (Creator)
Institution
Western Carolina University (WCU )
Web Site: http://www.wcu.edu/404.asp
Advisor
Laura DeWald

Abstract: Plants relying on insects to pollinate flowers attract pollinators through varying floral cues such as unique colors and scents. Pollinators rely on these cues to identify flowers for sources of food such as nectar, pollen, and oils. The goals of this study were to investigate color and odor cues associated with pollinator attraction in populations of Trillium at the Botanical Gardens, Asheville, NC. Insect visitors to the red-scented T. cuneatum and white-non-scented T. grandiflorum were collected using tangle-trap, bottle-traps, transect walk methods. Floral color and odor cues also were investigated using artificial flowers placed among a spring blooming plant community. Artificial flowers colored wine-red, white, or yellow and scented or unscented were covered with transparency film and sprayed with tangle-trap to capture insect visitors. Insects were identified to the level of order and family. Insect visitors to T. cuneatum and T. grandiflorum did not differ and primarily consisted of individuals belonging to the order Diptera, Hymenoptera, and Coleoptera. Diptera were the most abundant visitors consisting of weakly flying dipteran such as Sciaridae and Mycetophilidae. Similar to the real flowers the main visitors to artificial flowers were Diptera, Hymenoptera, and Coleoptera but also included 13 additional orders representing 106 families. Some orders and families collected showed low abundances that could reflect they were being repelled by the floral cues or might not be abundanct in the study area. Overall there was a difference in color (p < 0.05) but not odor (p > 0.05). However, when looking at each individual order or family separately, some orders and families were equally distributed for color and odor while others were not, indicating that the importance of floral cues depends on the insect family investigated. For those that were not equally distributed for color, insects were found in greater average percent of individuals on yellow flowers but there was no difference between red and white. For those that were not equally distributed for odor, a greater average percent of individuals were found on scented flowers. Some insects were generalists; visiting all artificial flower treatments randomly, while other insects were more specialized visiting certain color and/or odor treatments in greater numbers indicating a continuum along a gradient of generalized to specialized insect visitors. The ability for plants to attract generalist insect visitors and the ability for insects to visit multiple floral cues might be important where visitation is affected by varying weather conditions and advantageous in the event of environmental change and human altered ecosystems.

Additional Information

Publication
Thesis
Language: English
Date: 2011
Keywords
insect, plant, pollination, visitation
Subjects
Trilliums -- Pollination
Insect pollinators -- Behavior