Honey bee population meltdown in USA and things are getting worse

The honey bee population had another disaster – many describe it as a meltdown – over the past year in the USA, with beekeepers across the nation reporting a 44% decline in honey bee colony numbers  from April 2015 to April 2016, according to preliminary results of a nationwide survey that is carried out each year.

US beekeepers and everybody involved in the honey industry are alarmed – this is the second successive year when mortality during the summer months has rivalled that of the winter months.

The comprehensive survey, which asks both small-scale and commercial beekeepers to monitor the health and survival rates of their honey bee colonies, is carried out annually by the Bee Informed Partnership in collaboration with the Apiary Inspectors of America. The survey is funded by the USDA (US Department of Agriculture).

US honey bee loss estimates per yearSummary of the total overwinter colony losses (Oct 1 – Apr 1) of managed honey bee colonies in the US across 9 annual national surveys. The acceptable range is the average percentage of acceptable colony losses declared by the survey participants in each year of the survey. (Image: beeinformed.org)

All survey results are available to the public on the Bee Informed website.

Summer loss high 2 years running

Dennis vanEngelsdorp, an assistant professor of entomology at the University of Maryland and project director for the Bee Informed Partnership, said regarding the high summer losses:

“We’re now in the second year of high rates of summer loss, which is cause for serious concern. Some winter losses are normal and expected. But the fact that beekeepers are losing bees in the summer, when bees should be at their healthiest, is quite alarming.”

Survey respondents lost 44.1% of their colonies over a 12-month period, which is 3.5 percentage points more than during the previous 12-month period (2014-15), when loss rates came in at 40.6%.

Winter loss rates grew to 28.1% this past winter, compared to 22.3% in the previous winter, while summer loss rates rose to 28.1% from 25.3%.

Varroa miteVarroa mites (dark red blob) mainly feed on honey bee larvae, but spread from one hive to another on adult bees. The mites transmit disease, including a number of debilitating viruses. (Image: University of Maryland. Credit: Bee Informed Partnership)

Several causes for steep colony loss

The team members who carried out the survey explained that several factors have been contributing to the severe colony losses.

An evident culprit is the varroa mite, a deadly parasite that can spread easily between colonies. Pesticides and malnutrition caused by changes in land use patterns are also significant factors, especially among commercial beekeepers.

A recent study led by scientists from the University of Maryland and published in the journal Apidologie, reported that the varroa mite is considerably more abundant than previous estimates had indicated, and is closely linked to a number of damaging viruses.

Kirsten Traynor, a postdoctoral researcher in entomology at UMD, and lead author on the study that was published in Apidologie, said:

“Poor honey bee health has gained a lot of attention from scientists and the media alike in recent years. However, our study is the first systematic survey to establish disease baselines, so that we can track changes in disease prevalence over time. It highlights some troubling trends and indicates that parasites strongly influence viral prevalence.”

Varroa is an especially challenging problem for beekeepers with fewer than fifty colonies (backyard beekeepers).

Nathalie Steinhauer, a graduate student in the UMD Department of Entomology, leader of the data collection efforts for the annual survey, made the following comment regarding backyard beekeepers and the varroa mite:

“Many backyard beekeepers don’t have any varroa control strategies in place. We think this results in colonies collapsing and spreading mites to neighboring colonies that are otherwise well-managed for mites. We are seeing more evidence to suggest that good beekeepers who take the right steps to control mites are losing colonies in this way, through no fault of their own.”

Deformed Wing VirusA bee infected with Deformed Wing Virus, one of several viruses that the varroa mite transmits. (Image: University of Maryland. Credit: Bee Informed Partnership)

This is the tenth year of the winter loss survey, and the sixth year to include summer figures in the annual-loss totals. Over 5,700 beekeepers from across the country – 48 states – contributed to this year’s survey.

The survey-respondents account for approximately 15% of America’s estimated 2.66 million managed honey bee colonies.

Many crops rely on honey bees

This survey forms part of a much larger research project which aims to understand why honey bee colonies are in such deteriorating health, and what can be done to address this problem.

Honey bees are crucial for many crops. Almonds, for example, rely entirely on honey bees for pollination. Agricultural economists estimate that honey bee pollination services are worth approximately between $10 billion to $15 billion each year – and that is just in the United States!

Jeffery Pettis, a senior entomologist at the USDA and a co-coordinator of the survey, said:

“The high rate of loss over the entire year means that beekeepers are working overtime to constantly replace their losses. These losses cost the beekeeper time and money. More importantly, the industry needs these bees to meet the growing demand for pollination services. We urgently need solutions to slow the rate of both winter and summer colony losses.”

Pollinating animal population declining rapidly

The world’s food supply, which relies heavily on bees, birds, butterflies, beetles and other pollinating animals, is under threat because the populations of these creatures is declining alarmingly fast, say researchers. In fact, several species are facing a serious threat of total extinction.

Experts say that modern agricultural practices are partly to blame for the population declines across Europe and North America. In Europe, for example, at least 37% of bee species and 31% of butterfly species are declining.

How well or badly pollinators in other parts of the world, such as Latin America, Africa and Asia are faring is less clear, because we do not have enough data.

A team of researchers at the University of Cambridge in England, and two other centres across the world, say some simple strategies could boost agricultural production by harnessing pollinator power.

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