Research Training Program

Smithsonian Institution
National Museum of Natural History

PROJECT SUMMARY
1996

Matthew Kweskin
The Evergreen State College
Olympia, Washington
Ronald J. McGinley, Ph.D.
Supervising Scientist
Department of Entomology
"This program has greatly broadened my natural history education. This increased breadth and the experience from my project will have a life-long influence on my scientific career."

Ommatidia Size and Behavior of Male Bees

ABSTRACT
The insect's compound eye is made of many individual optical units called ommatidia. The size and the angle between adjacent ommatidia affect the optical qualities of the eye. The size of ommatidia varies within an eye. In the honeybee as well as several families of flies it has been found that the region of the eye used by males to track females in mating have enlarged ommatidia. These enlarged ommatidia are thought to give greater acuity. In this study the ommatidia size patterns of ten species of bees including the honeybee were studied. The male behavior was known for the species chosen. In six of the species there was little differences in ommatidia size between the sexes. In two of the species there were areas in the center of the male's eye where there were moderately enlarged ommatidia. The ommatidia size distribution of Xylocopa virginica, a common carpenter bee, was the only species examined with an ommatidia distribution similar to the honey bee. The males of this species had much larger ommatidia than the female in the upper portion of their eye. This is similar to what is known for the honey bee. Although the male mating behavior of this species of carpenter bee is known, not enough is known of the exact way that the male tracks females in flight to determine if these ommatidia patterns are correlated to behavior. With the expansion of this work to include more taxa, clearer patterns will emerge. If the eyes of males do tell of their mating behavior, this information would be very important scientifically and economically. From museum specimens, indications of mating behavior may be learned for species where the natural history is not well known.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-9531331.

Letter of Gratitude