The impact of greenhouse tomato (Solanales: Solanaceae) floral volatiles on bumble bee (Hymenoptera: Apidae) pollination

Abstract

Greenhouse tomato (Lycopersicon esculentum Mill) production relies on pollination by commercially-produced bumble bee (Bombus impatiens Cresson) colonies. Inadequate pollination by bumble bees has been a problem for growers at certain times of year; however, its cause has yet to be determined. Bumble bees have been shown to exit tomato greenhouses to forage on flowers of other plants. This study investigates tomato's floral characteristics and their affect on bumble bee pollination by 1) observing foraging preferences for bumble bees on greenhouse tomato, 2) determining if the plant's floral advertisements could be used by the bees to estimate pollen availability, and 3) identifying temporal changes in floral display which correspond to peak bumble bee activity. Flower size (petal length, anther cone width, and anther cone length) and floral scent (release of β-phellandrene, 2-carene, α-pinene, and p-cymene) were evaluated to identify the pollinator-important characteristics of tomato flowers. Our results indicate that 1) bumble bees preferred to pollinate flowers which produce less β-phellandrene and 2-carene in comparison to flowers producing more of these volatiles, 2) flower size and floral scent are not likely used by the bees to estimate pollen availability, and 3) cultivars are inconsistent in their production of floral volatiles during peak bumble bee activity, β-phellandrene and 2-carene may be antiherbivory volatiles and reduced production during peak bee activity may help to facilitate pollination of tomato. Pollinator-repellent volatiles may help to protect flowers from damage caused by over-pollination. © 2012 Entomological Society of America.