Candidate stress biomarkers for queen failure diagnostics
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RESEARCH ARTICLE
Open Access
Candidate stress biomarkers for queen failure diagnostics Alison McAfee1* , Joseph Milone1, Abigail Chapman2, Leonard J. Foster2, Jeffery S. Pettis3 and David R. Tarpy1
Abstract Background: Queen failure is a persistent problem in beekeeping operations, but in the absence of overt symptoms it is often difficult, if not impossible, to ascertain the root cause. Stressors like heat-shock, cold-shock, and sublethal pesticide exposure can reduce stored sperm viability and lead to cryptic queen failure. Previously, we suggested candidate protein markers indicating heat-shock in queens. Here, we further investigate these heat-shock markers and test new stressors to identify additional candidate protein markers. Results: We found that heat-shocking queens for upwards of 1 h at 40 °C was necessary to induce significant changes in the two strongest candidate heat-shock markers, and that relative humidity significantly influenced the degree of activation. In blind heat-shock experiments, we tested the efficiency of these markers at assigning queens to their respective treatment groups and found that one marker was sufficient to correctly assign queens 75% of the time. Finally, we compared cold-shocked queens at 4 °C and pesticide-exposed queens to controls to identify candidate markers for these additional stressors, and compared relative abundances of all markers to queens designated as ‘healthy’ and ‘failing’ by beekeepers. Queens that failed in the field had higher expression of both heat-shock and pesticide protein markers, but not cold-shock markers. Conclusions: This work offers some of the first steps towards developing molecular diagnostic tools to aid in determining cryptic causes of queen failure. Further work will be necessary to determine how long after the stress event a marker’s expression remains elevated, and how accurate these markers will be for field diagnoses. Keywords: Honey bees, Queens, Sperm viability, Biomarkers, Proteomics, Stressors, Spermatheca
Background According to surveys in Canada [1] and the US [2, 3], one of the most frequently reported causes of honey bee (Apis mellifera) colony failure is ‘poor queens.’ Unfortunately, the underlying factors leading to queen failure are usually difficult, if not impossible, to determine. For example, previous research has found that heat-shock, cold-shock, and pesticide exposure all decrease the viability of sperm stored in queen spermathecae [4, 5], which would theoretically lead to the same colony-level symptoms: inconsistent brood patterns, poor population * Correspondence: [email protected] 1 Department of Entomology & Plant Pathology, North Carolina State University, Raleigh, North Carolina, USA Full list of author information is available at the end of the article
build-up, and sometimes atypical drone-laying. If beekeepers cannot diagnose the root cause of queen failure, they are less equipped to identify the source of stress and are unable to make evidence-based management decisions to mitigate or eliminate
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