Elaborate courtship enhances sperm transfer in the Hawaiian swordtail cricket, Laupala cerasina

Males of many insect species engage in ritualized behaviours during courtship that include the donation of a food gift to their partner. Although there is extensive diversity in nuptial gift form, a gift provided before mating typically serves to facilitate copulation, thereby increasing a maleʹs mating success. Unlike other insects, the Hawaiian swordtail cricket Laupala shows protracted courtship that includes the serial donation of nuptial gifts prior to mating. Males transfer multiple spermless ‘micro’ spermatophores over several hours before the transfer of a single sperm containing a ‘macro’ spermatophore. By experimental manipulation of male courtship, we tested several hypotheses pertaining to the adaptive significance of protracted courtship involving nuptial gift donation in this system. We found that extensive courtship interactions improve insemination by causing the female reproductive tract to take in more sperm. This suggests that the enhancement of sperm transfer is due to the serial donation of microspermatophores, which would represent a relatively novel function for nuptial gifts provided before mating and highlights the importance of examining cryptic processes of sexual selection.