Effects of Reproductive State on Rhythmicity, Locomotor Activity and Body Weight in the European Honeybee, Apis mellifera Queens (Hymenoptera, Apini)

摘要

We investigated rhythmicity and locomotor activity level of virgin and laying queens of the European honeybee Apis mellifera L. to clarify the effects of mating and/or reproductive status on queen behavior. After entrainment at a 12L:12D light cycle,both virgin and laying queens showed significant free-running rhythms in constant darkness. This suggests that a circadian clock continues to run even in laying queens that are apparently arrhythmic in the colony. We also showed that laying queens have adecreased locomotor activity level compared to 6- or 12-day-old virgin queens. Although the effect of increased body weight due to ovarian development should be considered, inactivity could contribute to energy conservation, because laying queens probably do not have to be very active, unlike virgin queens. In addition, the body weight of virgin queens decreased gradually after emergence as a result of loosing body water. This seems reasonable because the mating flight probably requires a lighter body.