The first step in the act of pollination is to remove pollen from one flower and transfer it to another conspecific flower. Bees are considered quintessential pollinators due to their adaptations, e.g., barbed hairs on their bodies, to collect and transport pollen. Despite lacking such adaptations, many other insects regularly visit flowers and have been shown to move pollen. In this study we use pollen transport information acquired over several years in two habitats at Badlands National Park, South Dakota, USA, to compare probabilities of pollen transport among insect taxa, roles of taxa within network modules, and sexes of bees. Sampling was conducted on 1-ha plots, eight in sparse vegetation (July or September samples) and 12 in wheatgrass prairie vegetation (June – July samples), centered on plant species of interest. Insects in contact with reproductive parts of flowers were netted, placed individually into tubes charged with ethyl acetate, then transferred to individual labeled glassine envelopes for transport to the lab. Pollen was removed from insect bodies with fuchsin jelly cubes which were then mounted on microscope slides for identification. The probability of taxa transporting only conspecific pollen, mixed pollen, only non-conspecific, or no pollen was estimated with logistic regression.
Results/Conclusions
Bees carried an order of magnitude or more pollen than other taxa; beetles typically carried the next largest amount. Male bees carried < one-tenth as much pollen as females. On the four sparse plots sampled over two years in July, bees, beetles and flies were approximately equivalent in their probability of transporting conspecific pollen, but ants rarely carried any pollen. Bees were far more likely to carry mixed pollen loads. Results were similar between years at the July-sampled plots, but varied considerably at the four sparse plots sampled in September. In 2010, ants, bees, flies and wasps were similarly likely to carry only conspecific pollen, whereas in 2011 beetles were much more likely to do so than the other taxa. On wheatgrass prairie plots sampled in June – July 2012 beetles were most likely to transport purely conspecific pollen, but also most likely to carry no pollen. Among modularity roles, peripherals were most likely to carry no pollen on sparse plots, but connectors and hubs were likely to carry no pollen on the wheatgrass prairie plots. Considering the variation observed across habitat types and taxa, conservation of “pollinators” should extend across a variety of taxa.