Light alters calling-song characteristics in crickets.

Communication is crucial for mate choice and thus for the survival and fitness of most species. In the cricket, females choose males according to their calling-song attractiveness and, exhibiting positive phonotaxis, they approach the chosen male. Light has been widely reported to induce changes in crickets' daily activity patterns, including the males' stridulation behavior. It had remained unknown, however, whether light also affects the calling-song properties and thus may consequently also alter female choice. Here, we present a novel semi-automated process, enabling the analysis of calling-song properties in an extremely large sample size of recording sections from males subjected to lifelong light:dark (LD) or constant light (LL) conditions. Our findings revealed that the LD calling songs consisted of longer chirps, longer inter-syllable intervals and a higher proportion of 4-syllable chirps compared with those of LL males. We also conducted some preliminary female choice experiments suggesting that females (reared in LD conditions) exposed to playbacks of male calling songs exhibit a preference towards LD over LL recordings. We therefore conclude that illumination conditions such as constant light affect the male crickets' calling-song properties in a manner that may be discernible to the females. It remains unclear, however, how and to what extent female mate choice and the species' overall fitness are affected by these changes.