Foraging behavior of carpenter bees (Xylocopa micans) on vertical inflorescences: A study of choice behavior

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Keith D. Waddington - Committee Chair


I analyzed the effects of spatial location of nectar and associated flower color on choice behavior of carpenter bees (Xylocopa micans) foraging on vertical inflorescences. Flowers arranged on vertical inflorescences and the association of variable amounts of nectar and pollen with each flower is common in plants. In the field, animals foraging for nectar and/or pollen on vertical inflorescences concentrate their visits to the more rewarding flowers. What mechanisms elicit foragers responses to such non-random choices?In a field study, carpenter bees visited only a proportion of the flowers on Pontederia cordata inflorescences. They arrived mostly to the bottom third of the inflorescence, moved upward and departed after visiting the topmost flowers of the inflorescence.When bees foraged on artificial vertical inflorescences in the laboratory in which all flowers were yellow and contained 1 $\mu$l of 30% wt./wt. sucrose solution (nectar), the bees exhibited a similar pattern of behavior as observed on P. cordata inflorescences. When a nectar-rewarding flower was in a predictable spatial location but with color and shape of petals similar to the empty flowers, the bees did not visit solely the rewarding flowers. Rather, they arrived near the bottom of the inflorescence, moved upward and departed near the top of the inflorescence. However, the bees changed partially their arrivals at and departures from the inflorescences in response to different patterns of nectar dispersion.The bees' probability of staying or shifting to another inflorescence after visiting empty or nectar-bearing flowers, differed across different patterns of nectar.When nectar-rewarding and non-rewarding flowers were of different colors, the carpenter bees visited almost exclusively the flowers with nectar and ignored the empty flowers, regardless of the arrangements of those flowers in the vertical inflorescences. Given a choice between color of a flower and its spatial location, the bees chose the flower based on its color.


Biology, Ecology; Biology, Entomology

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