Colony Collapse Disorder: A Descriptive Study

Dennis Vanengelsdorp,Jeffery S Pettis,Eric Haubruge,Chris Mullin,Jim Frazier,Jay D Evans,Diana Cox-Foster,Maryann Frazier,David R Tarpy,Robyn Underwood,Claude Saegerman,Bach Kim Nguyen,Yanping Chen

doi:10.1371/journal.pone.0006481

Abstract

BackgroundOver the last two winters, there have been large-scale, unexplained losses of managed honey bee (Apis mellifera L.) colonies in the United States. In the absence of a known cause, this syndrome was named Colony Collapse Disorder (CCD) because the main trait was a rapid loss of adult worker bees. We initiated a descriptive epizootiological study in order to better characterize CCD and compare risk factor exposure between populations afflicted by and not afflicted by CCD.Methods and Principal FindingsOf 61 quantified variables (including adult bee physiology, pathogen loads, and pesticide levels), no single measure emerged as a most-likely cause of CCD. Bees in CCD colonies had higher pathogen loads and were co-infected with a greater number of pathogens than control populations, suggesting either an increased exposure to pathogens or a reduced resistance of bees toward pathogens. Levels of the synthetic acaricide coumaphos (used by beekeepers to control the parasitic mite Varroa destructor) were higher in control colonies than CCD-affected colonies.Conclusions/SignificanceThis is the first comprehensive survey of CCD-affected bee populations that suggests CCD involves an interaction between pathogens and other stress factors. We present evidence that this condition is contagious or the result of exposure to a common risk factor. Potentially important areas for future hypothesis-driven research, including the possible legacy effect of mite parasitism and the role of honey bee resistance to pesticides, are highlighted.

Highlights

The winter of 2006/2007 witnessed large-scale losses of managed honey bee (Apis mellifera L.) colonies in the United States [1]
Colony strength measurements As the operational case definition for Colony Collapse Disorder (CCD) was based, in part, by a clinical assessment that adult bee populations were in rapid decline, differences between non-affected and CCD-affected colony strength measures are not surprising (Table 2 and 3)
The odds ratio demonstrated that in CCD apiaries there was an increased risk of colonies being weak or dead when they neighbored other weak or dead colonies (Table 5). This suggests that CCD is either a contagious condition or results from exposure to a common risk factor

Summary

Introduction

The winter of 2006/2007 witnessed large-scale losses of managed honey bee (Apis mellifera L.) colonies in the United States [1]. In the U.S, a portion of the dead and dying colonies were characterized post hoc by a common set of specific symptoms: (1) the rapid loss of adult worker bees from affected colonies as evidenced by weak or dead colonies with excess brood populations relative to adult bee populations (Figure 1); (2) a noticeable lack of dead worker bees both within and surrounding the affected hives; and (3) the delayed invasion of hive pests (e.g., small hive beetles and wax moths) and kleptoparasitism from neighboring honey bee colonies [3] This syndrome has been termed Colony Collapse Disorder, or CCD.

Methods

Results

Conclusion