Consistent pollen nutritional intake drives bumble bee (Bombus impatiens) colony growth and reproduction across different habitats

Abstract

Foraging behavior is a critical adaptation by insects to obtain appropriate nutrients from the environment for development and fitness. Bumble bees (Bombus spp.) form annual colonies which must rapidly increase their worker populations to support rearing reproductive individuals before the end of the season. Therefore, colony growth and reproduction should be dependent on the quality and quantity of pollen resources in the surrounding landscape. Our previous research found that B. impatiens foraging preferences to different plant species were shaped by pollen protein:lipid nutritional ratios (P:L), with foragers preferring pollen species with a ~5:1 P:L ratio. In this study, we placed B. impatiens colonies in three different habitats (forest, forest edge, and valley) to determine whether pollen nutritional quality collected by the colonies differed between areas that may differ in resource abundance and diversity. We found that habitat did not influence the collected pollen nutritional quality, with colonies in all three habitats collecting pollen averaging a 4:1 P:L ratio. Furthermore, there was no difference in the nutritional quality of the pollen collected by colonies that successfully reared reproductives and those that did not. We found however, that “nutritional intake,” calculated as the colony‐level intake rate of nutrient quantities (protein, lipid, and sugar), was strongly related to colony growth and reproductive output. Therefore, we conclude that B. impatiens colony performance is a function of the abundance of nutritionally appropriate floral resources in the surrounding landscape. Because we did not comprehensively evaluate the nutrition provided by the plant communities in each habitat, it remains to be determined how B. impatiens polylectic foraging strategies helps them select among the available pollen nutritional landscape in a variety of plant communities to obtain a balance of key macronutrients.

Honey bee waggle dance communication increases diversity of pollen diets in intensively managed agricultural landscapes

“…However, the resource landscape did affect total nutrient uptake of bumble bee colonies, which had significant consequences for colony fitness (Vaudo et al, 2018). Contradicting the findings of I'Anson Price et al (2019), in our experimental setting colonies with disrupted directional dance communication gathered smaller amounts of pollen than unimpaired colonies (Nürnberger et al, 2017).…”

“…It is remarkable that the overall effect of dominance of mass‐flowering crops on diversity of pollen diets was actually small and, according to our results, colonies that were not able to communicate resource locations to nest mates still foraged on 15 different plant genera on average, even in landscapes in which resources consisted predominantly of mass‐flowering crops (i.e., over 95% of flower cover). A field study on bumble bees also showed that pollen nutritional value in terms of pollen‐lipid ratio did not differ between colonies in different landscapes (Vaudo, Farrell, Patch, Grozinger, & Tooker, ), presumably because foragers discriminate for pollen with favourable nutrition properties (Vaudo et al, ). However, the resource landscape did affect total nutrient uptake of bumble bee colonies, which had significant consequences for colony fitness (Vaudo et al, ).…”

“…A field study on bumble bees also showed that pollen nutritional value in terms of pollen‐lipid ratio did not differ between colonies in different landscapes (Vaudo, Farrell, Patch, Grozinger, & Tooker, ), presumably because foragers discriminate for pollen with favourable nutrition properties (Vaudo et al, ). However, the resource landscape did affect total nutrient uptake of bumble bee colonies, which had significant consequences for colony fitness (Vaudo et al, ). Contradicting the findings of I'Anson Price et al (), in our experimental setting colonies with disrupted directional dance communication gathered smaller amounts of pollen than unimpaired colonies (Nürnberger et al, ).…”

Floral Species Richness Correlates with Changes in the Nutritional Quality of Larval Diets in a Stingless Bee

“…The findings from this study may indicate that the beneficial effect of surrounding plant species richness on colony reproductive fitness may be driven by both a continuous resource supply and thus high food quantity over time (as suggested by Kaluza et al [44]), and also by increased food quality (e.g., through enhancing larval provisions with a low omega-6:3 ratio). Similar field studies on the effect of landscape on colony reproductive output also found a strong effect of resource abundance but no clear effect of resource nutritional quality [9,34]. However, several studies conducted in the laboratory showed a positive correlation between increasing pollen diversity in diets as well as resource nutrient (e.g., pollen protein) content and bee health [11][12][13][14][15].…”

“…Both the floral composition and the nutritional quality of bee bread were strongly affected by the surrounding foraging landscape: bee bread of higher protein content was found in environments that were comparatively less affected by anthropogenic activities [10,33]. Two studies on bumblebees did not find an effect of landscape on variation in the protein content and protein-to-lipid ratio of allocated pollen [9,34].…”