The effect of the dispersion of rewarding and rewardless flowers on visitation and constancy by bumblebees ( Bombus impatiens)

Abstract

Deceptive pollination strategies, in which plants rely on animal pollinators but provide no benefits to their pollinators, have evolved many times in angiosperms. However, the conditions that favour deceptive pollination strategies over mutualistic strategies are poorly understood. One factor that may be important for the success of deceptive strategies is the plants’ dispersion in relation to co-flowering, rewarding species. We compared pollinator behaviour across two artificial environments, one in which a rewardless species was mixed with a rewarding species and one in which the two species occurred in contiguous patches. Bumblebees both encountered and visited rewardless flowers more often when they were mixed with rewarding species. However, the rate of switching was also higher under those conditions, which could result in higher rates of interspecific pollen transfer. The environmental conditions most favourable to deceptive pollination strategies may vary depending on the vulnerability of the plant species to interspecific pollen transfer.