Pollination disruption by European honeybees in the Australian
bird-pollinated shrub Grevillea barklyana (Proteaceae).
Department of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.
Plant Systematics & Evolution. 1996. 200: 89-100
CAB Abstract 960605622
European honey bees (Apis mellifera) were less efficient pollinators of Grevillea barklyana than nectar-feeding birds. Nectar-collecting honey bees did not contact reproductive parts of flowers. Pollen-collecting honey bees preferentially visited male-stage flowers but rarely visited female-stage flowers. Fruit set on caged inflorescences that allowed access to honey bees but excluded birds was reduced by more than 50% compared to inflorescences that were visited by both types of visitor. Further, fruit set on caged inflorescences was less than on bagged inflorescences that excluded both birds and honeybees, indicating that pollen removal by bees decreased opportunities for delayed autonomous selfing in the absence of birds. Although fruit set was not pollen-limited at the study site, pollen removal by honey bees would decrease fruit set in small populations where birds are scarce. In addition, pollen removal by honey bees would reduce opportunities for outcrossing and reproductive success through male function. Although honey bees have been in Australia for insufficient time to have exerted selection on floral traits, evolutionary shifts in response to these animals are likely to occur in the future.