Lower pollen nutritional quality delays nest building and egg laying in Bombus terrestris audax micro-colonies leading to reduced biomass gain

Jordan T Ryder,Helen M Thompson,Keith F A Walters,Andrew Cherrill

doi:10.1007/s13592-021-00885-3

Jordan T Ryder, Helen M Thompson + Show 2 more

Open Access

https://doi.org/10.1007/s13592-021-00885-3

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Abstract

The performance of Bombus terrestris micro-colonies fed five diets differing in pollen species composition and level of nine essential amino acids (EAA; leucine, lysine, valine, arginine, isoleucine, phenylalanine, threonine, histidine, methionine) was assessed for 37 days by recording total biomass gain, nest building initiation, brood production (eggs, small and large larvae, pupae, drones), nectar, and pollen collection. Stronger colony performance was linked to higher amino acid levels but no consistent differences in biomass gain were recorded between mono- and poly-species diets. Poorest performance occurred in micro-colonies offered pure oilseed rape (OSR) pollen which contained the lowest EAA levels. Reduced micro-colony development (delayed nest initiation and lower brood production) was related to OSR proportion in the diet and lower EAA levels. Results are discussed in relation to selection of plant species in the design of habitats to promote bee populations.

Highlights

Bumblebees (Bombus spp.) are a key group of highly efficient wild pollinators, which forage on a wide variety of flowers and plants (Reynolds and Fenster 2008)
This study investigates the effect of five defined pollen diets on the development of B. terrestris audax micro-colonies to test the hypothesis that colony performance is defined, in part, by their amino acid profiles and the diversity of pollen species included
Sweet chestnut pollen (Castanea sativa) represented 65.5% of the grains identified from pollen marketed as “organic chestnut pollen”, with the remainder dominated by Prunus spp., Lotus corniculatus and B. napus (Table I)

Summary

Introduction

Bumblebees (Bombus spp.) are a key group of highly efficient wild pollinators, which forage on a wide variety of flowers and plants (Reynolds and Fenster 2008). Foraging behaviour of individual workers is highly selective (Harmon-Threatt et al 2017), and it has been proposed that the nutritional content of pollen affects flower selection (Nicolson 2011). The importance of pollen diversity is widely recognised, and habitat management schemes have focused on increasing floral diversity to enhance pollinator populations (Carvell et al 2006). Bumblebees have been shown to favour more protein-rich pollens (Leonhardt and Blüthgen 2012; Kitaoka and Nieh 2009) but amino acid composition is a better determinant of pollen quality for bees than total protein content (Nicolson, 2011; Moerman et al 2015, 2017; Stabler et al 2015)

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