Not all cockroaches are the same and some have larger respiratory systems, making them more likely to win physical battles, a new study has found.
Fighting between male cockroaches of the same size tends to be strength tests, researchers suggest.
They found that some insects have much greater respiratory capacity than others, allowing them to take control of the pests.
Dr Sophie Mowles, senior lecturer in animal and environmental biology at the University of Anglia Ruskin (ARU), said: “When studying competition behavior it is important to consider not only the physical weapons used. species use, or the fighting behaviors they use, but also the basic psychological ones that allow this costly behavioral behavior to occur.
“When visible differences are removed by size-matching opponents, fights between male cockroaches are more likely to lead to strength tests and our study found that respiratory abilities some cockroaches have much more than others, allowing them to control these competitions.
“The increased ability to deliver oxygen to their body tissues could strengthen the fighting ability of these strong men.
“Modifications for prolonged aerobic relief in these cockroaches may have emerged as a way to increase oxygen exchange as they dig through leaf litter, and we have shown that the cockroaches play a vital role. such changes in physical competitions between males, and thus sexual selection. ”
During laboratory competitions, researchers closely matched the cockroaches for size so there were no noticeable differences in their fighting abilities.
Full-horned male hissing cockroaches use their horns as they compete for females through vigorous competitions, often butting and flipping their male opponents on their backs.
What happened can happen to behavior that involves a number of approaches to the opponent, which can be reversed or adopt a low position to defend against a turnaround.
During the competitions, researchers found snippets of activity revealing these dominant and subversive behaviors in each cockroach.
A CT scan of each cockroach was then performed allowing the researchers to examine the entire body, including the size of their respiratory system.
The study, published in Animal Behavior, found that cockroaches had significant differences in respiratory volume, and these were directly related to their fighting abilities.
The larger ones were found to have larger breathing sizes compared to their similar opponents.