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Features -- Female fireflies fall for the flashy look



Female fireflies fall for the flashy look

Steve McReynolds
Globe Neosho Bureau

Success in love, at least for lightning bugs, is more a matter of timing than intensity, according to a researcher from the University of Kansas.

Marc Branham, KU graduate student, has studied the incandescent critters over the past three summers at Roaring River State Park.

``I was surprised that rate was so important. The females might be hard-wired to prefer the faster flash,'' said Branham.

Branham's findings were published in the June issue of the journal Nature. The British Broadcasting Corp. last summer traveled to Roaring River with Branham to produce a segment on his research.

He said his study of fireflies stemmed from his interest in bioluminescence, which is the emission of light by living organisms. Many species of animals and plants are bioluminescent, especially deep-sea fish. But deep-sea fish are difficult and expensive to study, so Branham decided to stay on dry land.

He chose to concentrate on fireflies, or lightning bugs, as they are known in the Ozarks. They're actually members of the beetle order, he said.

In some of the more than 2,000 species of fireflies, the pattern of the flight of the males is a factor in the mating ritual. But that made things too complicated. So Branham further narrowed his choice to the species Photinus consimilus because they hover in the air while they flash. The place nearest KU where naturalists had recorded an abundant supply of consimilus was Roaring River.

``The fireflies you see flying around on summer nights are the males, flashing for the females. The females stay on the ground, where the males can't see them. When they see a male flash pattern they like, they flash back, alerting the male that they are there and they are interested.''

In 1993, Branham videotaped the bugs to identify their flash patterns. With the help of KU physicist Jonathan E. Mericle, he developed a computerized device that emulated the male flash pattern.

In 1994, he spent several weeks at the park tricking females into responding to the flash of a computer-driven light-emitting diode. He flashed the light at rates that he had determined to be below average, average and above average, and waited for the flashing responses of ensconced females. He threw into the equation below-average and above-average rates that the computer could produce but that fireflies couldn't produce naturally.

``I caught the females outside and brought them nto the cabin, so I could test and be sure they could only see one male flash pattern that of the computer.

``Males that can broadcast faster get more matings. It's pretty unclear why the females prefer the higher rate,'' he said.

Average, he found, is about 3.3 flashes per second. At the naturally high rate of 3.6 flashes per second, love was in the air. The artificially high rate of 4.3 flashes per second drove the females wild. At the naturally low rate of 2.8 flashes per second and the artificially low rate of 2.5 flashes per second, the bugs and the computer ``couldn't get the time of day'' from the females.

Branham's research attracted the attention of the BBC. A British camera crew arrived at the park last summer just in time for a tornado and a flood. They waited for the lightning bugs to re-emerge from the disasters, and shot a piece that is to be broadcast as part of a series called ``Beetlemania.''

The research project was funded with grants from the American and KU museums of natural history, and the research society Sigma Xi. Branham plans to continue his research with other bioluminescent animals this fall as a doctorial candidate at Ohio State University.




Last Updated: Wednesday, August 07, 1996 10:29:14 AM

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