Baffling behavior in the tree cricket Oecanthus henryi : how is leaf area measured?

Abstract

Acoustic communication in animals generally serves many purposes including mate attraction and aggression. Males of tree crickets use acoustic communication to attract females. It has been observed that males of the tree cricket species Oecanthus henryi sing from leaf edges to attract females from a distance. Males have also been observed making holes in leaves and singing through them to amplify their song. Previous work has shown that O. henryi can measure leaf sizes and that they always choose relatively large leaves to make holes on, and sing through them to amplify their sound. Song amplitude gain is known to be much higher when a cricket sings from a hole on a bigger leaf compared to that on a smaller one. With females selectively choosing loud males in the environment, there would be immense pressure on such a behavior to evolve. This thesis attempts to elucidate the mechanisms underlying the leaf area-measuring ability of O. henryi. Experiments conducted, indicated that the behavior of individuals on different sized leaves are different. Insects were found not to be using petiole features or hypothetical walks which were correlated well with area. The mean free path of individuals on small leaves was significantly lower than that on large leaves suggesting that it could potentially be used for estimation of leaf areas.