UC Davis

Nectar microbe-produced volatiles can contribute to floral blends and modify pollinator preference for flowers. Identifying and describing the compounds that may underlie this effect is a key goal. Semi-quantitative or quantitative data is often critical for chemical ecology investigations, given that biotic responses (i.e., insects or plants) can fluctuate with concentration, relative ratios, or composition of the emitted volatile profiles. However, field-based, in situ microbial volatile detection and quantification is difficult due to the small scale of the nectar microhabitat. Laboratory-based inoculations of bulk synthetic nectars are useful for screening weakly-abundant and difficult to analyze volatiles, which may be crucial in eliciting responses. Despite the limitations of this approach, it allows rapid identification of target molecules for further validation with bioassays. Targeted analytical methods to identify or quantify semiochemicals may then be developed and validated for field tests. Here, we report the first quantitative assessment of microbe volatile emission in laboratory-based tests with synthetic nectar. We also review briefly solid-phase microextraction collection and gas-chromatography data interpretation. Nectar microbe interactions with plants and insects offer opportunities for agricultural improvement, and a selection of potential uses are highlighted.