Bumble bee (Hymenoptera: Apidae) activity and loss in commercial tomato greenhouses

Abstract

AbstractActivity of bumble bees,Bombus impatiensCresson, was examined in commercial tomato,Lycopersicon esculentumMill. (Solanaceae), greenhouses in relation to greenhouse covering type, solar radiation, greenhouse temperature and humidity. Bumble bee activity was measured by photodiode monitors inserted into the entrance of the colonies. Colony sizes were monitored as an indicator of bee loss through gutter ventilation systems in relation to covering. Activity monitors were found to be a good predictor of actual bumble bee entrances and exits (r2= 0.85). Bumble bee activity was 94.0% greater under the ultravioltet (UV)-transmitting covering than under ones that transmitted less UV light. No relationship was found between bee activity and the amount of solar radiation or internal greenhouse humidity. Bee activity was weakly positively correlated with internal greenhouse temperature (r2= 0.18). Bee activity was not different during three periods of the day: morning, midday, and evening. The mean ± SE colony size under the UV-transmitting covering was 86.0 ± 2 bees per colony after 10 days within the greenhouses, compared with 36.4 ± 5.8 bees per colony under the other three types of covering. Our results suggest that bee activity is greatest and bee loss through gutter ventilation systems lowest in greenhouses made with coverings that transmit high levels of UV light.