Small bushcricket boasts big assets
It may only be half the size of a human finger, but the Tuberous Bushcricket is the species with the largest testicles in relation to its body weight, according to a new study.
Researchers from the universities of Derby and Cambridge found the species, Platycleis affinis, produces testes which are 14% of its whole male body mass.
This beats a species of fruit fly (Drosophila bifurca), thought to be the previous record holder for the biggest testes as a percentage of male body mass, at 10.6%.
But despite this experts believe the bushcricket does not necessarily produce the largest amount of sperm - contrary to traditional thinking.
The research, led by biologists at the University of Derby, is published in Royal Society Journal Biology Letters.
Lead researcher Dr Karim Vahed, Reader in Behavioural Ecology at the university, said: "We couldn't believe the size of these organs; they seemed to fill the entire abdomen.
"We are also interested in the reason why they are so large.
"An almost universal evolutionary rule appears to be that such variation in relative testes size is linked to female mating behaviour.
"Testes tend to be larger in species where females are more promiscuous, as has been demonstrated in various species in fish, birds, insects and mammals.
"But at least two hypotheses could account for this pattern - sperm competition on the one hand and male mating rate on the other."