January 2010 Featured Paper
"Male Photuris Fireflies Mimic Sexual Signals of Their Female's Prey" by Dr. James Lloyd, University of Florida, Science Vol. 210, November 7, 1980.
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Fireflies of the genera Photuris, Photinus, and Pyractomena use flashes of light for sexual communication. Females of the genus Photuris also use flash signals to mimic females of other species to attract males and eat them. Studies in the field show that several male Photuris fireflies can also mimic males Photinus and Pyractomena.
In early spring in Florida, unnamed Photuris males mimic two species of Pyractomena. The Photuris has a flash pattern of 3 - 7 flashes from high in the trees, but during the time Pyractomena was active, they were seen to fly a few meters off the ground, giving flashes in short flickers (mimicking P. barberi) or a minutes-long bright glow (mimicking P. angustata).
Individual Photuris males can often be seen to change both their flight altitude and flash pattern, switching from their own mating behavior to that of the Pyractomena species. At least five Photuris species mimic the flicker of Pyractomena angulata, a common and widespread firefly.
One Photuris species in Florida emits a single, long flash early in the evening, mimicking Photinus collustrans — a dusk-active species — and switches to a 1 - 5-pulse pattern to mimic Photinus lineellus when that firefly becomes active later in the evening.
- The male Photuris are locating the hunting female Photuris fireflies and forcing them to mate. However, the female Photuris is larger than the male and attempts at forced mating may be unsuccessful.
- It is believed that the female Photuris alternately lays eggs and hunts over several days. After laying eggs, she could be receptive to a male's attempts at mating. On five occasions when males located a female by mimicry, they landed and immediately switched their flash pattern to their pulsing treetop mating pattern.
- Males that are able to switch correctly between their own mating flash and the mimicked flash may be demonstrating a trait that the females find favorable.
- Based on the flash patterns they are imitating, males may be signaling to females their willingness to sacrifice for their progeny. For instance, an older male that might not survive to mate another night might be signaling to a hungry female that he is offering himself up as a meal after mating, to provide the female the nourishment needed for her eggs to survive.
In choosing from the above hypotheses, number two is the most likely. However, more than one explanation may be involved.
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