Floral resource selection by wild bees and honey bees in the Midwest United States: implications for designing pollinator habitat

Abstract

Many seed mix recommendations for creating pollinator habitat are in part based on anecdotal evidence or field observations of bees visiting forbs (i.e. use). However, there is limited information on what forbs are preferred by bees, particularly in working landscapes where bee forage may be limited. We examined floral resource selection by wild bees and honey bees on grasslands in the Midwest using a 5‐year dataset containing over 8,000 plant‐bee interactions. We observed wild bees visiting 83 forb species, but only 14 species were significantly selected (i.e. bees visited a plant more than expected based on availability). Approximately 70% of all wild bee visitations were on native flowers, whereas only 20% of all honey bee visitations were on natives. Honey bees visited 70 forb species, but only four forbs were significantly selected. The selection ratio for each forb species was not correlated with proportion of use by wild bees or honey bees, suggesting that bee visitation data alone do not elucidate patterns of forb selection or avoidance. We then compared our resource selection results to forbs recommended by U.S. Department of Agriculture (USDA) for regional pollinator habitat plantings. Many forbs that were selected by bees in our study were also recommended by USDA; however, some USDA‐recommended forbs were selected against by bees. A greater understanding of which floral resources are selected by bees can assist land managers in assessing conservation seed mixes and ultimately provide diverse, season‐long pollinator forage in working landscapes.

Forbs included in conservation seed mixes exhibit variable blooming detection rates and cost‐effectiveness: implications for pollinator habitat design

“…Combining results from which seeded forbs are most often observed blooming and pollinator preference research would identify forb species that (1) readily bloom under realized conditions on private lands, (2) provide high pollinator value, and (3) cost less for private landowners and taxpayers. Our previous work on wild bee and honey bee flower preferences (Simanonok et al 2021) can be combined with our current study to identify forbs that fit these conditions. Out of all non-noxious weed forbs selected by honey bees, all were considered cost-effective in our present study (i.e.…”

Wild bee visitors and their association with sown and unsown floral resources in reconstructed pollinator habitats within an agriculture landscape

“…We acknowledge that by doing so, the pollinator network at each site does not include all Apidae pollinators, and consequently may have different nestedness and modularity measurements than networks that include honeybees. However, a recent study conducted in the same region of the United States has demonstrated that in similar restored grassland habitat, honeybees and wild bees had different floral preference and avoidance (Simanonok et al ., 2021). Honeybees were observed to show preferences for the most abundant forbs throughout the season, many of which were introduced species, while native bees were shown to select for another set of forbs, many of which were native species, and their preference varied throughout the season as the floral composition changed.…”

“…3a). This is not surprising because these sown flower species are often chosen due to their documented attractiveness to pollinators as 'bee plants' (Harmon-Threatt & Hendrix, 2015;Simanonok et al, 2021), and this contributes to the previously documented success of small-scale restoration projects like pollinator gardens. However, unlike a heavily managed, weeded pollinator garden, in a large-scale reconstruction project like the CP-42 programme, floral sources established in the habitat are not necessarily the intentionally sown 'bee plants'.…”

“…All three unsown species were observed to be visited by A. wilkella . Several studies have shown that restored grassland habitat tends to support more generalist bees as the restoration often uses ‘easy to access’ plants preferred by generalists (Seitz et al ., 2020; Simanonok et al ., 2021). Our results further demonstrate biased support for some plant family specialists because long‐lasting, showy, easy to establish plant families such as Asteraceae are used disproportionately.…”

Patch utilization and flower visitations by wild bees in a honey bee‐dominated, grassland landscape

“…Research from California and New Jersey has shown wild bees will readily use, but not necessarily prefer, non-native flowers (Williams et al, 2011). Wild bees in the PPR will visit non-native flowers and even exhibit preference for some, but a majority of the preferred flowers are native (Simanonok et al, 2021). In some cases, non-native…”