Crickets have always been well known for their distinctive creaking calls that are often heard around twilight or during warm summer afternoons.
Surprisingly, a recent study unveils that young male crickets who have never heard a cricket song while in their juvenile stages developed into more aggressive adults as they age. This study suggests that insect young can pick up certain behavioural traits while young and then carry them onwards into their adulthood.
In fact, scientists believe that this is a necessity in the development of the species and vastly contributes to ecology and evolution. These latest studies were published in the journal Animal Behaviour and the study carried out by the University of California in Davis, the United States.
The experiment was carried out by capturing wild field crickets that are still in their juvenile stages. These young crickets have not yet developed their tympanum, which is located on the cricket’s front legs. The tympanum is the equivalent of the ear, so crickets initially start out as deaf while in their youth.
“We isolated them all effectively before any of them could hear anything” says Nicholas Di Rienzo, the lead author of the study. They basically split the young crickets into two groups: one was exposed to a looped recording of five calling cricket males while the second group was left in silence.
“In the sound treatment there was a chorus of five different crickets playing back, calling, to mimic just what you would hear on a summer night, lots of different crickets calling and singing.”
This study was made because scientists noted a distinct difference between crickets that were hatched in spring and crickets that hatched later on in the summer. Crickets that hatched during spring time were born in quieter conditions because the cricket population is lower. They were therefore exposed to prolonged periods of silence compared to the ones born during the summer, where more cricket songs could be heard.
DiRienzo and his team suggests that juvenile crickets use the sounds in order to determine the number individuals of the current cricket population and therefore affects their behaviours as they mature. Crickets that were raised in high density populations tend to be less aggressive than the ones that were reared in low density cricket populations.
The theory behind it is that when the population numbers are low, females and potential mates would be few and far between, prompting juvenile males to be more aggressive. The extra aggression could help the animals secure the proliferation of their progeny later on. These males are more likely to fight other males for the rights to mate, but only the stronger animal survives.
On the other hand, high density populations call for less aggression because it allows each cricket to preserve its life while still having a chance to mate.