Can insect body pollen counts be used to estimate pollen deposition on pak choi stigmas?

Abstract

Measuring pollen deposition onto stigmas by insects is one technique used to assess pollinator effectiveness, but it can be unpredictable and time-consuming as insects must visit test flowers. This study examined whether a measurement of pollen grains from flower-visiting insects could be used to predict pollen deposited on stigmas. Individuals were collected from four bee and six fly species as they visited pak choi flowers in commercial and trial seed fields to assess their body pollen. Pollen was removed from insects by pressing their bodies (excluding actively-collected pollen on bees' hind legs) with a cube of gelatine-fuchsin. In this study, there appears to be a strong correlation between mean estimated pollen counts for each insect species and previously published data recording mean number of pollen grains deposited on stigmas for the same species. Therefore, the measurement of pollen grains directly from flower-visiting insects shows potential as a quicker and easier technique to assess pollinator effectiveness as insects can be directly collected from flowers.