Honey bee (Apis mellifera) colony health and pathogen composition in migratory beekeeping operations involved in California almond pollination

Abstract

Honey bees are important pollinators of agricultural crops. Pathogens and other factors have been implicated in high annual losses of honey bee colonies in North America and some European countries. To further investigate the relationship between multiple factors, including pathogen prevalence and abundance and colony health, we monitored commercially managed migratory honey bee colonies involved in California almond pollination in 2014. At each sampling event, honey bee colony health was assessed, using colony population size as a proxy for health, and the prevalence and abundance of seven honey bee pathogens was evaluated using PCR and quantitative PCR, respectively. In this sample cohort, pathogen prevalence and abundance did not correlate with colony health, but did correlate with the date of sampling. In general, pathogen prevalence (i.e., the number of specific pathogens harbored within a colony) was lower early in the year (January—March) and was greater in the summer, with peak prevalence occurring in June. Pathogen abundance in individual honey bee colonies varied throughout the year and was strongly associated with the sampling date, and was influenced by beekeeping operation, colony health, and mite infestation level. Together, data from this and other observational cohort studies that monitor individual honey bee colonies and precisely account for sampling date (i.e., day of year) will lead to a better understanding of the influence of pathogens on colony mortality and the effects of other factors on these associations.

Home sick: impacts of migratory beekeeping on honey bee (Apis mellifera) pests, pathogens, and colony size

“…Previous studies found that DWV was a good predictor of weaker colonies ( Budge et al, 2015 ) and thus one would not expect our results to simply be attributed to an increase in numbers and thus exposure. One potential explanation is that the migratory bees returned from pollinating almonds with a more virulent DWV strain that disseminated quickly in the exposed group as a result of their larger colony size and higher Varroa population ( Martin, 2002 ; Rosenkranz, Aumeier & Ziegelmann, 2010 ; Glenny et al, 2017 ). Using deep sequencing, viruses not previously found in honey bees have been detected in migratory hives ( Runckel et al, 2011 ) and recently, a more virulent recombinant of DWV was found to replicate at high levels when transmitted by Varroa mites ( Ryabov et al, 2014 ).…”

“…A limited number of observational surveys have compared disease loads of colonies belonging to migratory and stationary operations and found a higher prevalence of some pathogens in migratory colonies ( Traynor et al, 2016b ) including Nosema ceranae ( Zhu, Zhou & Huang, 2014 ) and RNA viruses ( Welch et al, 2009 ), some of which were not previously described in honey bees ( Runckel et al, 2011 ). However, the focus of previous studies has been the collection of baseline disease data to characterize diseases in migratory colonies and, as such, rarely control for migratory conditions, management practices, and sampling times, all of which can significantly affect disease loads and colony health ( Runckel et al, 2011 ; Glenny et al, 2017 ). Furthermore, studies examining the impact of migratory conditions on bees rarely include a control group of stationary colonies for comparison (but see Zhu, Zhou & Huang, 2014 ; Simone-Finstrom et al, 2016 ).…”

Peer Review #3 of "Honey bee viruses in Serbian colonies of different strength (v0.1)"

“…Additional investigations are necessary to explain the observed significant differences. It can be assumed that these results may reflect the beekeepers' negligence of apicultural measures (Stanimirovic et al, 2007a), but also may have risen from different means of V. destructor control (Nielsen, Nicolaisen & Kryger, 2008) Manuscript to be reviewed which may be the reason only in ABPV infection, since not all viruses are transmitted by varroa mites (Glenny et al, 2017). Nevertheless, differences in orographic factors and forage quality between regions should be also considered as the environment was suggested as a key factor interacting with local bee populations and ecogenotypes Giacobino et al, 2016).…”

Effectiveness of the smoke of fruits of Guazuma ulmifolia (Sterculiaceae) and vapors of Thymol for control of Varroa destructor infesting Africanized bees

“…Estos resultados corroboran que la aplicación de cristales de timol es una alternativa para el control del ácaro V. destructor en Yucatán, y que la aplicación del humo de los frutos secos de G. ulmifolia reduce los niveles de infestación de este parásito en comparación con las colonias que no recibieron ningún tipo de tratamiento (G3). (1) , continúa siendo uno de los principales problemas sanitarios a los que se enfrenta la actividad apícola a nivel mundial, representando una seria amenaza para esta actividad, al afectar el desarrollo, sobrevivencia y productividad de las colonias de Apis mellifera destinadas a la producción de miel (2,3) y a la polinización de cultivos agrícolas (4) .…”