A leading cause of managed honey bee colony mortality in the US, Varroa destructor populations typically exceed damaging levels in the fall. One explanation for rapid population increases is ...migration of mite carrying bees between colonies. Here, the degree to which bees from high and low mite donor colonies move between apiaries, and the effect visitation has on Varroa populations was monitored. More bees from low mite colonies (n = 37) were detected in receiver apiaries than bees from high mite colonies (n = 10, p < 0.001). Receiver colony Varroa population growth was associated with visitation by non-natal bees (p = 0.03), but not high mite bees alone (p = 0.19). Finally, colonies lacking robbing screens experienced faster Varroa population growth than screened neighbors (p = 0.01). Results indicate visiting non-natal bees may vector mites to receiver colonies. These results do not support the current two leading theories regarding mite immigration - the "mite bomb" theory (bees from high mite colonies emigrating to collapsing colonies), or the "robbing" theory (natal robbing bees return home with mites from collapsing colonies). Potential host-parasite effects to bee behavior, as well as important management implications both for Varroa treatment regimens and breeding Varroa resistant bees are discussed.
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.
There exists a lack of control efficacy information to enable decision-making about which organic insecticide product works best for a given insect pest. Here, we summarize results of 153 field ...trials on the control efficacy of common active ingredients in organic insecticides against 12 groups of the most difficult to control insect pests. These trials evaluated primarily the organic products Entrust (spinosad), Azera (pyrethrin and azadirachtin), PyGanic (pyrethrin) and Neemix (azadirachtin), which reduced pest infestations by an overall 73.9%, 61.7%, 48.6% and 46.1% respectively, averaged across all trials. Entrust was the most effective control option for many insect pests, particularly providing >75% control of flea beetles, Colorado potato beetle, cabbageworms and alfalfa weevil, but was relatively ineffective against true bugs and aphids. Azera provided >75% control of green peach aphid, flea beetles, Japanese beetle, Mexican bean beetle, potato leafhopper and cabbageworms. PyGanic was less effective than Entrust and Azera but still provided >75% control of green peach aphid, flea beetles and potato leafhopper. The growth inhibition effects of azadirachtin in Neemix were particularly effective against larvae of Mexican bean beetle and Colorado potato beetle but was generally less effective in trials with insect infestations consisting mainly of adult stages. Those insect pests that were particularly difficult to control included thrips, stinkbugs, cucumber beetles and fruitworms. Several caveats pertaining to the application of the results are discussed.
Little is known about the economics of small-scale beekeeping, due in part because many of these beekeepers are motivated by personal enjoyment and not profit. These beekeepers, however, represent ...more than 90% of US beekeeping population, so economic analysis of this majority group is warranted. Understanding how management practices impact colony profitability in small apiaries can inform beekeeper management decisions. Best management practices (BMPs) can increase colony productivity and survival, but often require additional labor and materials compared to less intensive beekeeping practices. Here, we investigate the impact of BMPs on the profitability of small-scale beekeeping. We found that BMPs required higher costs in labor and materials, but that they also produced higher revenue from honey and nucleus colony production. As a result, after three years, BMP apiaries were 8 times more profitable than less intensively managed apiaries. The increased profitability in BMP apiaries is largely attributed to improved colony health and survival due to more active Varroa management and reduced Varroa and viral loads. These results can inform small scale beekeeper budgeting and management, and also support extension efforts to increase BMP adoption.
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.
Fire has a major impact on the structure and function of many ecosystems globally. Pyrodiversity, the diversity of fires within a region (where diversity is based on fire characteristics such as ...extent, severity, and frequency), has been hypothesized to promote biodiversity, but changing climate and land management practices have eroded pyrodiversity. To assess whether changes in pyrodiversity will have impacts on ecological communities, we must first understand the mechanisms that might enable pyrodiversity to sustain biodiversity, and how such changes might interact with other disturbances such as drought. Focusing on plant–pollinator communities in mixed‐conifer forest with frequent fire in Yosemite National Park, California, we examine how pyrodiversity, combined with drought intensity, influences those communities. We find that pyrodiversity is positively related to the richness of the pollinators, flowering plants, and plant–pollinator interactions. On average, a 5% increase in pyrodiversity led to the gain of approximately one pollinator and one flowering plant species and nearly two interactions. We also find that a diversity of fire characteristics contributes to the spatial heterogeneity (β‐diversity) of plant and pollinator communities. Lastly, we find evidence that fire diversity buffers pollinator communities against the effects of drought‐induced floral resource scarcity. Fire diversity is thus important for the maintenance of flowering plant and pollinator diversity and predicted shifts in fire regimes to include less pyrodiversity compounded with increasing drought occurrence will negatively influence the richness of these communities in this and other forested ecosystems. In addition, lower heterogeneity of fire severity may act to reduce spatial turnover of plant–pollinator communities. The heterogeneity of community composition is a primary determinant of the total species diversity present in a landscape, and thus, lower pyrodiversity may negatively affect the richness of plant–pollinator communities across large spatial scales.
Varroa destructor is a primary cause of honey bee colony death in the US. Multiple chemical treatment options exist, but their effectiveness can vary due to factors including ambient temperature and ...reproductive cycles. Thus some treatment options may be preferable to others at specific times of the year. Here, we tested the efficacy of a late season oxalic acid drip treatment and an application of HopGuard strips, compared to an untreated control. Resulting changes in mite populations were measured immediately after treatment application, the following spring during almond pollination, and again upon return to Washington State. Immediately after treatment application, both oxalic acid and HopGuard treatments resulted in a greater increase in mite mortality compared to the untreated control. In almonds, both oxalic acid and HopGuard groups had lower mite loads than the untreated control and were still below the economic threshold of 3 mites per 100 bees. By March, mite loads had evened out between groups, indicating that spring may be an important time to reevaluate mite loads and apply another treatment. There was no difference in colony size or mortality between the groups at any time throughout the study.
Managed honey bee colony losses are of concern in the USA and globally. This survey, which documents the rate of colony loss in the USA during the 2015-2016 season, is the tenth report of winter ...losses, and the fifth of summer and annual losses. Our results summarize the responses of 5725 valid survey respondents, who collectively managed 427,652 colonies on 1 October 2015, an estimated 16.1% of all managed colonies in the USA. Responding beekeepers reported a total annual colony loss of 40.5% 95% CI 39.8-41.1% between 1 April 2015 and 1 April 2016. Total winter colony loss was 26.9% 95% CI 26.4-27.4% while total summer colony loss was 23.6% 95% CI 23.0-24.1%, making this the third consecutive year when summer losses have approximated to winter losses. Across all operation types, 32.3% of responding beekeepers reported no winter losses. Whilst the loss rate in the winter of 2015-2016 was amongst the lowest winter losses recorded over the ten years this survey has been conducted, 59.0% (n = 3378) of responding beekeepers had higher losses than they deemed acceptable.
Honey bee queens are the most critical individuals of a complex eusocial society. Queen banking is the storage of queens individually in cages and placed in a colony to be cared for by worker bees. ...Queen producers bank excess queens as seasonal demand subsides in the summer to provide an on-demand supply to beekeepers. This approach, however, might be threatened by wildfires, decreased forage availability, and climate change. For this study, we compared current summer outdoor queen banking practices in northern California with banking in indoor temperature-controlled storage facilities to investigate the effectiveness of indoor storage as an alternative to outdoor storage in the summer. Treatments were separated into three groups: indoor queen banks, outdoor queen banks, and a set of unbanked control queens provided with three different stocking rates (50, 100, and 198 queens per bank). Queen quality parameters and survival data were assessed using laboratory and field assessment methods. We found no significant difference in queen quality parameters apart from the weight of indoor queens banked at the rate of 100, which were significantly lower than the other banking rates. Queens stored indoors had a significantly higher survival of 78 ± 1% than queens stored outdoors with a survival of 62 ± 3%. Indoor banking performed better in quality and survival as compared to outdoor queen banking. Therefore, queen banking has the potential to mitigate the valuable fall queen supply caused by rising hot summer temperatures.
Honey bees (Apis mellifera, L.) provide critical pollination services to many US crops, but decades of high colony loss rates have strained beekeepers’ ability to provide sufficient colonies for crop ...production. In a national survey of colony losses for the 2015-2016 season, beekeepers reported losses averaging at 37.4%, and that the parasitic mite Varroa destructor was a leading cause of mortality. Survey results were used to create empirical best management practices (BMPs) to reduce colony loss rates. Best practices were the top four practices which correlated to significant reductions in winter colony loss. This set of BMPs was tested on 140 colonies in 7 locations across the US, compared to average beekeeping practices. At the end of 3 years, apiaries managed according to BMPs exhibited reduced Varroa loads, which resulted in reduced fall viral loads and reduced winter mortality. However, colony loss rates still exceeded rates that beekeepers have deemed acceptable.A prominent factor affecting colony health and mortality in the BMP study was Varroa. After identifying Varroa treatment as a preventative measure, the effects of Varroa management were evaluated in non-experimental apiaries. Citizen scientist beekeepers participating in the Sentinel Apiary Program provided Varroa samples and Varroa management information. Out of 192 Varroa treatments applied to 155 apiaries over 2 years, only 45 treatments resulted in reduced Varroa loads. Common hypotheses of factors affecting Varroa population growth failed to explain the rapid increases in Varroa loads experienced by beekeepers in critical fall months. Finally, a more novel explanation for rapid increases in Varroa load was explored: horizontal transmission of mites between apiaries. Colonies that were visited by non-natal bees experienced larger increases in Varroa loads than unvisited colonies, but not as a result of visitation to or from high mite colonies. High mite colonies in the landscape represent a threat to nearby colonies, and cooperative Varroa management is likely to mediate colony losses resulting from Varroa. This dissertation supports the critical need for proactive, cooperative Varroa management to improve colony health and reduce mortality.
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