Wild Bumblebee (Bombus) Diversity andNosema(Microsporidia: Nosematidae) Infection Levels Associated with Lowbush Blueberry (Vaccinium angustifolium) Production and Commercial Bumblebee Pollinators

Sara L Bushmann,Eleanor Groden,Lee A Beers,Francis A Drummond

doi:10.1155/2012/429398

Abstract

The primary objective was to determine if the prevalence ofNosema bombiinfection is higher for wild bumblebees (Bombusspp.) caught in lowbush blueberry growing areas with a history of commercial bumblebee use than for bumblebees caught in areas without a history of commercial bumblebee use. Additionally, we wished to determine relativeBombusspecies abundances and diversity in blueberry growing regions. Over two years we caught, identified to species, and dissected 767 bumblebees. Light microscopy revealed overall infection levels of 5.48%. The history of commercial bumblebee use had no relation to infection levels. Bumblebee species diversity and field location had significant relationships to infection (r2adjusted = 0.265; species diversityF(1,22)=6.848,P=0.016; field regionF(1,22)=5.245,P=0.032). The absence or presence of one species,Bombus terricola, appears to determine the relationship between species diversity and infection. The data showB. terricoladecline in sampled regions and almost half of the collectedB. terricolawere infected withNosema. The commercial species,B. impatiens, shows an increase in abundance, but with a 6.9% proportion infection. Molecular confirmation of the infecting species was ambiguous, suggesting a need for future clarification of the infecting species.

Highlights

Native bumblebees (Bombus spp.) serve as valuable pollinators for the lowbush blueberry (Vaccinium angustifolium Aiton) fields in Eastern Maine and Maritime Canada and Quebec
The data provide no support for our prediction that the use of commercial bumblebees (B. impatiens) in Maine’s blueberry fields has increased the prevalence of Nosema infection in those fields that have a history of commercial bumblebee use
The total infection level of 5.48% does not indicate that coastal areas of blueberry production in Maine have an elevated prevalence of infection

Summary

Introduction

Native bumblebees (Bombus spp.) serve as valuable pollinators for the lowbush blueberry (Vaccinium angustifolium Aiton) fields in Eastern Maine and Maritime Canada and Quebec. Queens are the predominant foragers during blueberry bloom in Maine [1]. They are known to be effective pollinators due to their ability to forage in cool or rainy conditions [2], which commonly occur during lowbush blueberry bloom in Maine [3], and their use of sonication to remove pollen grains from the Vaccinium poricidal anthers [4]. Many farmers wish to use a native species and many express a hope to populate their fields with subsequent generations of wild bumblebees [9]

Objectives

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Conclusion