DISSERTATION RESEARCH: Recognition of host plant floral chemistry in the specialist bee clade Diadasia inferred from electroantennography coupled with GC/MS

Southern Illinois University At Carbondale, Carbondale IL

Investigators

Abstract

Modern agriculture is overly-dependent on honeybees for pollination. Considering the current decline in honeybee populations worldwide, this is an ill-fated limitation. Alternative pollinators surely exist among the 30,000 other bee species, but unfortunately basic biological information for most of them is lacking. Unlike honeybees, most wild bees are solitary, not social. Many also have a specialized diet and are limited to collecting pollen from only a few plant species, even when others are available. For example, the bee genus Diadasia comprises ~30 species in North America. Each species uses only one of the following plant families as a pollen-host: mallows, cacti, morning glories, evening primroses, or sunflowers. DNA analyses suggest that the ancestor of Diadasia collected only mallow pollen, but at some point in the past a few switched their loyalties to one of the other four plant families. This project attempts to discover the mechanisms that 1) maintain these bees' specialized diets, and 2) mediate or constrain host-switching events. How are novel hosts 'chosen' by specialists? This project tests the hypothesis that specialist bees have a limited ability to recognize visual and odor cues of different flowers, and that they are therefore unable to recognize non-host flowers as potential pollen resources. The project also tests the prediction that the five families of host plants used by these bees share visual or chemical (i.e. scent) characteristics. First, analyses of the floral scent chemistry of host and co-blooming non-host plants will be conducted. Second, electroantennography will be used to discern which flower scent compounds can be recognized by specialist bees. And finally, behavioral trials will be conducted to assess the relative roles of visual and odor cues. Understanding these mechanisms will enhance the conservation of native bee and plant biodiversity, and provide necessary information for developing specialized crop pollinators.