The parasitic mite Varroa destructor (Acari: Varroidae) is a major cause of overwintering honey bee (Apis mellifera) colony losses in the United States, suggesting that beekeepers must control Varroa ...populations to maintain viable colonies. Beekeepers have access to several chemical varroacides and nonchemical practices to control Varroa populations. However, no studies have examined large-scale patterns in Varroa control methods in the United States. Here we used responses from 4 yr of annual surveys of beekeepers representing all regions and operation sizes across the United States to investigate use of Varroa control methods and winter colony losses associated with use of different methods. We focused on seven varroacide products (amitraz, coumaphos, fluvalinate, hop oil, oxalic acid, formic acid, and thymol) and six nonchemical practices (drone brood removal, small-cell comb, screened bottom boards, powdered sugar, mite-resistant bees, and splitting colonies) suggested to aid in Varroa control. We found that nearly all large-scale beekeepers used at least one varroacide, whereas small-scale beekeepers were more likely to use only nonchemical practices or not use any Varroa control. Use of varroacides was consistently associated with the lowest winter losses, with amitraz being associated with lower losses than any other varroacide product. Among nonchemical practices, splitting colonies was associated with the lowest winter losses, although losses associated with sole use of nonchemical practices were high overall. Our results suggest potential control methods that are effective or preferred by beekeepers and should therefore inform experiments that directly test the efficacy of different control methods. This will allow beekeepers to incorporate Varroa control methods into management plans that improve the overwintering success of their colonies.
Honey bee colony losses in the US have exceeded acceptable levels for at least a decade, leaving beekeepers in need of management practices to improve colony health and survival. Here, an empirical ...Best Management Practice (BMP) regimen was tested, comprised of the top four management practices associated with reduced colony mortality in backyard beekeeping operations according to Bee Informed Partnership Loss and Management survey results. Seven study locations were established across the US, and each location consisted of ten colonies treated according to empirical BMPs and ten according to average beekeeping practice. After 3 years, colonies treated according to empirical BMPs experienced reduced Varroa infestation, viral infection, and mortality compared to colonies managed with Average practices. In addition, BMP colonies produced more new colonies via splits. The colonies under Average practices were given chemical Varroa treatments only once per year, and thus spent more months above economic threshold of 3.0 mites/100 bees. Increased time spent above the economic threshold was significantly correlated to both increased viral infection and colony mortality. This study demonstrates the cumulative effects of management and colony health stressors over months and years, especially the dire importance of regular Varroa monitoring and management.
For the past six years in which overwintering mortality of honey bee colonies has been surveyed in the USA, estimates of colony loss have fluctuated around one-third of the national population. Here ...we report on the losses for the 2012-2013 seasons. We collected data from 6,482 US beekeepers (6,114 backyard, 233 sideline, and 135 commercial beekeepers) to document overwintering mortality rates of honey bee colonies for the USA. Responding beekeepers reported a total 30.6% (95% CI: 30.16-31.13%) loss of US colonies over the winter, with each beekeeper losing on average 44.8% (95% CI: 43.88-45.66%) of their colonies. Total winter losses varied across states (range: 11.0% to 54.7%). The self-reported level of acceptable winter loss was 14.6%, and 73.2% of the respondents had mortality rates greater than this level. The leading self-identified causes of overwintering mortality were different according to the operation type; backyard beekeepers generally self-identified "manageable" factors (e.g., starvation, weak colony in the fall), while commercial beekeepers generally identified non-manageable factors (e.g., queen failure, pesticides) as the main cause of losses. For the first time in this series of surveys, we estimated mortality during the summer (total loss = 25.3% (95% CI: 24.80-25.74%), average loss = 12.5% (95% CI: 11.92-13.06%)). The entire 12-months period between April 2012 and April 2013 yielded a total loss of 45.2% (95% CI: 44.58-45.75%), and an average loss of 49.4% (95% CI: 48.46-50.43%). While we found that commercial beekeepers lost fewer colonies than backyard beekeepers in the winter (30.2% (95% CI: 26.54-33.93% vs 45.4% (44.46-46.32%) respectively), the situation was reversed in the summer where commercial beekeepers reported higher average losses than backyard beekeepers (21.6% (95% CI: 18.4-24.79%) vs 12.1% (11.46-12.65%)). These findings demonstrate the ongoing difficulties of US beekeepers in maintaining overall colony heath and survival.
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•First to spatially analyze long-term honey bee colony loss data across entire U.S.•Results show spatial approach is essential for investigating honey bee colony loss.•Nov. mean max. ...temperature and Feb. mean precipitation were predictors of loss.•Weather conditions during winter better predict winter loss at the national scale.
Western honey bees (Apis mellifera) have experienced elevated rates of colony loss over the past decade. Past studies have attempted to determine what factors are behind these losses; however, few have considered the effects of environmental variables; key drivers in ecological systems. Existing investigations were conducted at local spatial scales, over small geographic areas, and failed to measure how environmental variables may influence colony loss rates differently across space. Here, we sought to determine the ability of environmental variables to explain honey bee colony winter loss rates across the contiguous U.S. over a nine-year study period, while elucidating how spatial methods produce results which differ from non-spatial approaches. To conduct this study, loss data from stationary beekeepers were obtained from the Bee Informed Partnership’s national Colony Loss and Management Survey for winters spanning from 2011 to 2019 and were aggregated by zip code. Environmental data (i.e., temperature, precipitation, relative humidity, wind speed, elevation) were obtained from PRISM, the Global Wind Atlas, and the U.S. Geological Survey, and averaged by month across the study period. Environmental variables and loss were regressed using linear and geographically weighted regressions. Results demonstrated that effects of environmental variables on colony loss varied across space, indicating that spatial models should be used when studying honey bee colony losses. Additionally, we found that increased winter colony loss rates were linked to lower November mean maximum temperatures and less February mean precipitation, thus, these two variables may be good predictors of observed winter loss rates. Finally, results also revealed that weather conditions during winter months were better predictors of winter colony loss than conditions during other months of the year. Overall, our results illustrate how environmental factors strongly impact managed honey bees and highlight the importance of regionally specific management practices to help prevent losses in the future.
A metagenomic analysis of the virome of honey bees (
) from an apiary with high rates of unexplained colony losses identified a novel RNA virus. The virus, which was named
solinvivirus 1 (AmSV1), ...contains a 10.6 kb positive-strand genomic RNA with a single ORF coding for a polyprotein with the protease, helicase, and RNA-dependent RNA polymerase domains, as well as a single jelly-roll structural protein domain, showing highest similarity with viruses in the family
. The injection of honey bee pupae with AmSV1 preparation showed an increase in virus titer and the accumulation of the negative-strand of AmSV1 RNA 3 days after injection, indicating the replication of AmSV1. In the infected worker bees, AmSV1 was present in heads, thoraxes, and abdomens, indicating that this virus causes systemic infection. An analysis of the geographic and historic distribution of AmSV1, using over 900 apiary samples collected across the United States, showed AmSV1 presence since at least 2010. In the year 2021, AmSV1 was detected in 10.45% of apiaries (95%CI: 8.41-12.79%), mostly sampled in June and July in Northwestern and Northeastern United States. The diagnostic methods and information on the AmSV1 distribution will be used to investigate the connection of AmSV1 to honey bee colony losses.
Beekeepers attempt to manage their honey bee colonies in ways that optimize colony health. Disentangling the impact of management from other variables affecting colony health is complicated by the ...diversity of practices used and difficulties handling typically complex and incomplete observational datasets.
We propose a method to 1) compress multi-factored management data into a single index, to holistically investigate the real world impact of management on colony mortality, and 2) simplify said index to identify the core practices for which a change in behavior is associated with the greatest improvement in survivorship.
Experts scored the practices of US beekeepers (n = 18,971) documented using four years of retrospective surveys (2012–2015). Management Index scores significantly correlated with loss rates, with beekeepers most in line with recommendations suffering lower losses. The highest ranked practices varied by operation type, as recommendations accounted for the current prevalence of practices. These results validate experts' opinion using empirical data, and can help prioritize extension messages. Improving management will not prevent all losses; however, we show that few behavioral changes (in particular related to comb management, sources of new colonies and Varroa management) can lead to a non-negligible reduction in risk.
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•An innovative and integrative approach to assess beekeeping practices using observational data•Demonstrated the association between management practices quality and overwintering success•Validated experts' opinion on best practices, and provided new insights on their relative ranking•Evidence based prioritization of behavior changes tailored to the type of operation
Cooperative colony founding (pleometrosis) in social insects is an ideal model for investigating how cooperation and competition shape social behaviour among unrelated individuals. In many ant ...species, foundress associations are more competitive and the colonies survive better compared with single-queen colonies. However, cooperation among queens breaks down at the time of emergence of the first workers, and all but one queen are eliminated. Because no sexuals are produced in incipient colonies, the surviving queen will monopolize the future reproductive success of the colony, while defeated queens will have zero fitness. We examined factors affecting queens' survival prospects during reversion to single-queen colonies in cooperative foundations of the ant
Lasius niger. By combining phenotypic and genotypic analyses, we determined how queen's size, individual investment and maternity apportionment influence the outcome of fights. Larger queens were more likely to survive fights. However, smaller queens survived up to one-third of the fighting. By contrast, neither weight loss at the time of a fight outbreak, a measure of queens' relative investment in brood production, nor maternity apportionment influenced the outcome of fights. Moreover, investment of cofoundresses and partitioning of reproduction were not adjusted to queen's size, suggesting that reproductive competition among queens does not occur before the emergence of the first workers. These results lead us to consider pleometrotic associations in
L. niger as a ‘best of a bad job’, whereby the benefits of joint founding and the probability of surviving the conflict might be sufficient for smaller queens to embark on cooperative foundations.
Drivers of colony losses Steinhauer, Nathalie; Kulhanek, Kelly; Antúnez, Karina ...
Current opinion in insect science,
April 2018, 2018-04-00, Letnik:
26
Journal Article
Recenzirano
Over the past decade, in some regions of the world, honey bee (Apis mellifera L.) colonies have experienced rates of colony loss that are difficult for beekeepers to sustain. The reasons for losses ...are complex and interacting, with major drivers including Varroaand related viruses, pesticides, nutrition and beekeeper practices. In these endeavors it has also become apparent that defining a dead colony, and singling out the effects of specific drivers of loss, is not so straightforward. Using the class of neonicotinoid pesticides as an example we explain why quantifying risk factor impact at the colony level is at times elusive and in some cases unpractical. In this review, we discuss the caveats of defining and quantifying dead colonies. We also summarize the current leading drivers of colony losses, their interactions and the most recent research on their effects on colony mortality.
Beekeepers in the United States have experienced high losses of managed honey bee (Apis mellifera) colonies for more than a decade. Long-term, multi-year monitoring efforts are crucial to provide a ...temporal and spatial context to these losses. To document and explain these losses, the Bee Informed Partnership has conducted national surveys on managed honey bee colonies since spring 2011, continuing the work of surveys first commissioned by the Apiary Inspectors of America in spring 2007. Here we present survey results from three years - 2017-18, 2018-19, and 2019-20. Each year, colony loss rates were estimated and compared among three loss periods - summer, winter, and annual - and three beekeeping operation types based on their number of colonies managed - backyard (≤50 colonies), sideline (51-500 colonies), and commercial (>500 colonies). At the national level, we recorded the highest winter colony loss rates (37.7%) in 2018-2019, while 2019 marked the year with the highest summer losses (32.1%). As documented in past surveys, we observed that smaller scale backyard beekeepers experienced the highest winter loss rates when compared to the larger operation types. Similarly, commercial beekeepers experienced higher loss rates during the summer compared to the other operation types. Overall, our results highlight the temporal variability, specifically among loss periods and years, of colony loss rates in the United States, and suggest a strong effect of beekeeping operation size.
Honey bees Apis mellifera forage in a wide radius around their colony, bringing back contaminated food resources that can function as terrestrial bioindicators of environmental pesticide exposure. ...Evaluating pesticide exposure risk to pollinators is an ongoing problem. Here we apply five metrics for pesticide exposure risk (prevalence, diversity, concentration, significant pesticide prevalence, and hazard quotient (HQ)) to a nation-wide field study of honey bees, Apis mellifera in the United States. We examined samples from 1055 apiaries over seven years for 218 different pesticide residues and metabolites, determining that bees were exposed to 120 different pesticide products with a mean of 2.78 per sample. Pesticides in pollen were highly prevalent and variable across states. While pesticide diversity increased over time, most detections occurred at levels predicted to be of low risk to colonies. Varroacides contributed most to concentration, followed by fungicides, while insecticides contributed most to diversity above a toxicity threshold. High risk samples contained one of 12 different insecticides or varroacides. Exposures predicted to be low-risk were nevertheless associated with colony morbidity, and low-level fungicide exposures were tied to queen loss, Nosema infection, and brood diseases.
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•A US national survey of pesticide residues in bee pollen found only 18% of samples were pesticide free. .•In our 1055 samples we made 2933 pesticide detections, predominantly at low risk levels. .•However, some low risk residues like fungicides were linked to increased colony morbidity. .•Neonicotinoids were rarely detected (2.0%), but contributed significant risk when found. .
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