Washington, Nov 10 : A study has found that Tuberous Bushcricket (Platycleis affinis) produces testes, which are 14percent of the male body mass, making it a species that has the largest testicles in relation to body weight on the planet.
"We couldn't believe the size of these organs, they seemed to fill the entire abdomen," said Dr Karim Vahed at the University of Derby.
Yet the research team also discovered that large testes did not necessarily relate to a larger amount of sperm produced - which goes against traditional thinking in the science world.
The researchers compared relative testes size across 21 species of bushcricket. They found testes were proportionately larger in species where females mated with more males.
However, the surprise was that the Tuberous bushcricket did not produce more sperm: in fact they produced less voluminous ejaculates.
"Traditionally it has been pretty safe to assume that when females are promiscuous, males use monstrously-sized testicles to deliver huge numbers of sperm to swamp the competition - even in primates. Our study shows that we have to rethink this assumption. It looks as though the testes may be that big simply to allow males to mate repeatedly without their sperm reserves being exhausted," said Dr. James Gilbert at the University of Cambridge.
Sperm competition is most intense when the female of the species mates with many males; the male that has produced the most sperm is often assumed to be at an advantage, hence the development of larger testes in such species.
The researchers suggest these findings offer food for thought about the links between endowment, promiscuity and reproduction within insects in the biological world.
The research is published today in Biology Letters, a Royal Society Journal.