Applications to agriculture and conservation
A frequently collected pollen morphotype, Fabaceae_Tricoloporate
pollen, likely came from a mix of white clover and alfalfa, as honey bee
and bumble bee foragers carrying pollen pellets were often observed
foraging for pollen on these plant species (personal observation). While
there were fields of soybean (Glycine max ) at the agricultural
research station, the pollen of which could not be reliably
distinguished from alfalfa or white clover in this study, soybean
flowers are cleistogamous, and may not actually open and be accessible
to bees (Erickson, 1975). On the other hand, alfalfa and white clover
contain nutritional rewards that are attractive to pollinators, and
white clover is frequently documented as being an abundantly collected
pollen type by honey bees (Keller, Fluri, & Imdorf, 2005). In other
agricultural systems, the prevalence of weedy plants, such as white
clover in collected pollen has been documented for honey bees (Requier
et al., 2018), along with bumble bees and other wild bees (reviewed in
Bretagnolle and Gaba 2015). In this study, bees did forage on diverse
weedy resources such as those from Fabaceae and Asteraceae on the
experimental farm, in addition to probable garden resources such as
Geraniaceae by honey bees. Furthermore, we did not observe more than a
few pollen grains (contamination levels) coming from maize over the
entirety of the study despite the presence of maize fields at the
agricultural research station. Honey bees have previously been observed
collecting maize when available, but it may actually decrease the
longevity of individuals when consumed exclusively (Höcherl, Siede,
Illies, Gätschenberger, & Tautz, 2012). These results suggest that bees
avoid corn pollen when more favorable resources are present and
emphasizes the importance of providing diverse resources for bees that
persists throughout the flowering season in human altered systems.