UC San Diego

Interspecific relationships among pollinators and predators give insight to pollination and plant fitness for a given ecosystem. We focused on pollinator-predator interactions on three common native plants (Eriogonum fasciculatum, Baccharis pilularis, Encelia californica) in California coastal sage scrub habitat. When allowed to forage at an array of five inflorescences (one with a crab spider), the pollinators (honey bees, Vespidae, other Diptera and other Hymenoptera) exhibited fear by spending less time on the dangerous inflorescence. There is also a spatial effect that depends upon pollinator type. Syrphid flies spent more time on safe inflorescences that were further away from the dangerous inflorescence. We then focused on honey bees (Apis mellifera), the most common visitor to these native plants. Honey bees exhibited fear and significantly avoided a feeder with crab spider odor. However, they did not avoid an artificial spider that did not provide spider odor. When spider odor was added to the model, they showed significant avoidance. This suggests that honey bees used olfaction as the primary cue to identify crab spiders (Mecaphesa celer and Xysticus elegans). In addition, honey bees avoided the odors of dead heterospecific pollinators (Villa lateralis, Agapostemon texanus, Ceratina sp. and Vespula pensylvanica) that are abundant in their environment. Thus, pollinator fear of predation mediated by olfactory detection can allow information about predator danger to flow in a community of pollinating insects