THE FUNCTION OF POST-INSEMINATION MATE ASSOCIATION IN THE BULB MITE, RHIZOGLYPHUS-ROBINI

Copulation in Rhizoglyphus robini usually lasts only 20 min, but pairs may associate for many hours. The aim of this study was to examine th e function of the prolonged mate association in this species. Prolonge d copulations did not result in the transfer of more sperm. Females ma ted frequently, but males that remained in association with females ef fectively prevented their re-mating with other males. In double mating s the proportion of eggs fertilized by the second male to mate was 0.5 37. When the time between female matings was manipulated, the proporti on of eggs a male fertilized increased with the time the female took t o re-mate with another partner. These findings indicate that prolonged mate association functions as a form of post-copulatory mate guarding : a male that can exclude other males from mating with the female he i nseminated benefits by increasing his paternity. Also consistent with the mate-guarding hypothesis was the finding that the duration of pair association increased with the male:female ratio, but was independent of the frequency of previous female matings. (C) 1996 The Association for the Study of Animal Behaviour