November 7, 2013
Scientists Find Rare Fossil Of Mating Froghopper
Researchers writing in the journal PLOS One say they have found the oldest fossil of insects caught in the act of mating. Scientists have very limited knowledge of mating position and genitalia orientation in ancient insects because fossil records are scarce. However, the latest discovery helps broaden the picture of how ancient bugs did it, adding more data to help scientists study the early stages of evolution.
“Mating behaviors for extant insects have been studied and documented, for example, for froghoppers, scorpionflies and planthoppers,” the researchers wrote in the journal. “However, fossil records of unequivocal insect mating are fairly sparse. Boucot and Poinar listed 33 instances of fossilized mating insects, such as fireflies, mosquitoes, planthoppers, leafhoppers, water striders, bees and ants, 27 of which are preserved in amber, others on compression fossils.”
The researchers discovered a fossil of a pair of copulating froghoppers, or Anthoscytina perpetua, in northeastern China. Froghoppers were a type of small insect that hopped from plant to plant similar to tiny frogs.
The fossil shows a holotype male on the right and a allotype female on the left lined up with each other belly to belly. A three-dimensional recreation of the mating behavior shows the two insects would have been holding on to a plant stem while copulating. The researchers wrote a very graphic description of the copulating insects in the journal.
“They exhibit belly-to-belly mating position as preserved, with male's aedeagus inserting into the female's bursa copulatrix. Abdominal segments 8 to 9 of male are disarticulated suggesting these segments were twisted and flexed during mating,” the authors wrote. “Due to potential taphonomic effect, we cannot rule out that they might have taken side-by-side position, as in extant froghoppers. Genitalia of male and female, based on paratypes, show symmetric structures.”
Researchers say this is the earliest record of copulating insects to date. The evidence suggests froghoppers’ genital symmetry and mating position have remained static for over 165 million years.
"We found these two very rare copulating froghoppers which provide a glimpse of interesting insect behavior and important data to understand their mating position and genitalia orientation during the Middle Jurassic,” said Dong Ren of the Capital Normal University in China.