The raspy cricket is the champion of chomp. Found in the rainforests of north-eastern Australia, this cricket has the strongest bite of around 650 insect species collected from four continents. Their bite strengths have been recorded in the largest ever database of such data, which could aid future research into the evolution of bite forces and their role in mating, feeding and fighting.
鈥淚 was initially surprised by the raspy cricket. I would have expected that maybe predators are the strongest biters rather than herbivores,鈥� says at the University of Bonn in Germany. But it makes more sense when you consider that the raspy cricket (Chauliogryllacris acaropenates) bites into living wood to dig out nests at points in a tree where a branch has fallen off, he says.
Before now, researchers had measured bite forces for only around 20 insect species. Now, R眉hr and his colleagues have expanded this to hundreds more, including crickets, stag beetles, praying mantises, termites, wasps, bees and ants from Australia, China, Europe and Panama. Between 2018 and 2021, they collected insects using light traps, nets or by turning over stones.
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To measure the power of their jaws, the researchers built a tiny metal device containing a crystal that stores electrical energy. They placed the sensor between the tips of each insect鈥檚 mouthparts, called the mandibles. When an insect bites down, it compresses the crystal, converting the mechanical energy into an electrical current. The voltage produced is proportional to the bite strength.
Some insects were hesitant to bite even with the device between their mandibles, so a threatening paintbrush was used to tickle their abdomen or head to spur a bite. Others, such as stoneflies, refused to bite at all.
The weakest biter was a wasp (Netelia) found in Australia, whose maximum bite force was around 1200 times less than that of the raspy cricket.
Several stag beetle species (Prosopocoilus) ranked near the top of the pile. 鈥淭he stag beetles had a lot of force 鈥� one even broke its own mouthparts [during the biting test],鈥� says R眉hr. From an initial look at the database, it seems insects that fight more may have stronger bite forces, he says.
While it is an interesting data set, interpreting the biological relevance of bite force requires relating it to the animal鈥檚 size, weight, food source or mating strategy, says at the University of Cologne in Germany.
R眉hr and his team are now combining their data with information on the insects鈥� ancestry and anatomical information to shed light on how insect bite forces have evolved.
鈥淚t鈥檚 just the beginning. There are more than a million insect species, many of them are biting and chewing, and we just measured 650,鈥� says R眉hr.
听搁eference: BioRxiv, DOI:聽
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