Analysis of courtship flash behaviour in two Photuris fireflies (Coleoptera: Lampyridae) with field validation and rearing notes

ABSTRACT The fireflies Barber and Barber from East Tennessee were reared in the laboratory from eggs through to adults. Duration to pupation, body mass and sex ratios were recorded. Virgin adult females were used for courtship studies recorded using video equipment. Analysis began with discriminating flashes associated with courtship communication from those which are not. A responsive virgin female would respond to some of the male flashes. These dialogues identified the male “advertising flashes” and the female “response flashes”. Other non-dialogue flashes were considered “periodic flashes”. In , the male advertising flash pattern was two to five flashes emitted ca. 0.7-sec intervals. The female response was a flash train with one to nine flashes emitted at ca. 0.2-sec intervals. The female flash train often started during the third male flash. Males seemed to synchronize flashes with each other when one male was in a flash dialogue with a female. The flash dialogue was a continuing duet of male and female flashes. The male flashed once in ca. 3 sec while the female flashed ca. two times in 3 sec. The female response flashes were ca. 1-sec apart and started ca. 1 sec after the male flash and her third flash sometimes synchronized with the second male flash. Male did not seem to synchronize with each other. The “periodic flashes” had a frequency distribution with a peak at ca. 1 sec. They seemed to have some periodicity so they are being called “periodic flashes”, a separate type of flash. Periodic flashes were produced by both males and females as they move about in the jar, cage or on vegetation. The function of periodic flashes is unknown, but they would seem to be perfect aposematic warning signals to keep predators at bay. These are some of the first detailed descriptions of courtship communication in fireflies.

Keywords: courtship flash behaviour, flash-answer, flash duet, growing degree days, , , synchronized flashing