Alexandra Sourakov has logged hours of research at the University of Florida’s butterfly house. She used a combination of behavioral experiments and electorantennography (measurements of electrical current in butterfly antennae) to determine how butterflies find food. Her most recent paper on foraging in Blue Morpho butterflies appears in this month’s edition of Psyche – Journal of Entomology. Alexandra Sourakov is also about to finish her sophomore year of high school.
Sourakov began her study as part of an eighth grade science project. She used the butterflies in the University of Florida Natural History museum’s butterfly house to see whether flower-feeding and fruit-feeding butterflies responded differently to color. Sourakov used different colored landing pads baited with food to see whether butterflies preferred brightly colored surfaces to black. She found that flower- feeding butterflies were attracted to bright hues, but that fruit-feeding butterflies were indifferent to color. Presumably, flower-feeding butterflies evolved to respond to color cues because they aid in finding brightly colored flowers, while fruit-feeding butterflies usually feed on fruit that has fallen to the dark forest floor, where visual cues would be of little use.
After winning the science fair, Sourakov decided to scale up her research program to investigate how the fruit feeding butterflies found their food. If they weren’t using color, how did they find fruit? Partnering with USDA researcher and science fair judge Adrian Duehl, she launched a multi-faceted approach to understanding butterfly foraging. Sourakov and Duehl used gas chromatography to determine what chemicals in rotting fruit might be attractive to butterflies. They applied these chemicals as volatiles to the antennae of Blue Morpho and Owl butterflies. These two fruit-feeding species did not show any preferences for color during the experiment. With the help of electrodes, they measured the electrical output when the butterfly was exposed to different chemicals. They found that several chemicals that give bananas their distinctive odor provoked a response in the butterfly antennae. Even more interesting, they found that it wasn’t only the antennae that registered a response of the chemical, the legs and proboscis (feeding tube) also responded to the scents. The labial palpi (mouth parts on a butterfly’s head below the antennae) reacted to a different set of chemicals, indicating that butterflies may use multiple organs to detect a variety of odors.
“I was surprised by the results from the body parts because I wasn’t even sure if any of them, except the antennae, would react to the volatile chemicals,” said Alexandra Sourakov in an interview to the University of Florida News. “This was interesting because it shows a joint message may be sent to the brain from these different organs. This expands our understanding of butterflies’ sense of smell.”
The researchers hope that their work will allow them to develop new types of bait designed to target specific species of insect, while leaving other species unaffected. You can read Alexandra’s full article here: http://www.hindawi.com/journals/psyche/2012/378050/