Honey Bee Health

The single largest culprit of colony losses is the parasitic mite Varroa destructor. Sometimes compared to a ‘dirty needle’, Varroa mites make a hole and feed on honey bees, vectoring viruses and bacteria as it feeds. The mite was introduced from Asia, and the Western honey bee is very vulnerable to this pest. Left unchecked, this mite will kill most honey bee colonies. 

Most beekeepers use chemical treatments to control Varroa mites and keep colonies alive. This is not ideal because chemical treatments are costly and laborious, have variable results, can leave residues, and may have sublethal effects on the bees themselves. Mites have also repeatedly developed resistance to chemical treatments. ​

Beekeepers desperately need more tools to control Varroa mites. Unfortunately, the market for these tools is quite small in comparison to other markets for new pest control research and development. Another, more sustainable approach to managing Varroa is through the development and use of mite-resistant bees. A variety of mechanisms such as grooming and brood removal are known. The best-characterized mechanism of resistance is the behavioral trait called Varroa sensitive hygiene (VSH). Bees that express VSH can detect reproducing Varroa in capped brood and remove the infested larvae, ensuring that Varroa do not successfully reproduce, keeping mite populations low.

Learn more about VSH Bees:

For an excellent source of Varroa control tools and Best Management practices, please visit the Honey Bee Health Coalition’s Tools for Varroa Management

Bees encounter viral, bacterial, and fungal pathogens that can have serious impacts on colony health and survival. Some of these pathogens are highly contagious on their own, and others can also be spread by the Varroa mite.

Beekeepers maintain constant vigilance and routines to combat pathogens, including administering preventative varroacides and other treatments as needed.

Some infections are more worrisome than others. The spore-forming bacteria that causes American foulbrood (AFB) is so persistent that destroying the colony completely is recommended to prevent the spread of this disease.

AFB

Because of diseases like AFB, each state has an apiary inspection program to help beekeepers deal with pathogens, and prevent the spread of disease. This is also why many beekeepers manage bees within a colony that has removable frames. Getting an up-close look and sample of the honey bee brood is essential to monitoring colony health.  

You can find your State Apiarist Here. 

As problematic as bacterial and fungal infections are for honey bees, viruses are incredibly wide-spread, due to the prevalence of the Varroa mite.

Deformed Wing Virus (DWV)

This chart from the Bee Informed Partnership shows the Prevalence of Deformed wing virus (DWV). DWV is closely linked to varroa mite infection. On average DWV is found in roughly 80% of bee colonies sampled across the United States. Bees with twisted, deformed wings are a sure sign of DWV infection (and Varroa mite infestation). The bees, unable to fly, can be seen crawling in front of the colony. Explore the Bee Informed Partnership database here.

Just like humans, honey bees are better able to stay healthy if properly nourished, and the best source of nutrition is from natural sources – in the case of bees, a diversity of blooming plants.

Access to floral resources is essential to honey production, and good nutrition helps mitigate other health stressors including Varroa, pesticides, and pathogens.

Honey bees and native pollinators are literally “losing ground” as agricultural land use expands. Corn and Soybeans are the two monoculture crops that use the most land in the USA. These crops do not depend on bees for pollination and tend to be heavily treated with an agricultural chemical

The above chart, sourced from USDA data, illustrates the growth in corn and soy crops since 1986 along with the decline in acres enrolled in the Conservation Reserve Program (CRP). The Conservation Reserve Program is a land conservation program administered by the Farm Service Agency (FSA). In exchange for a yearly rental payment, farmers enrolled in the program agree to remove environmentally sensitive land from agricultural production and plant species that will improve environmental health and quality. This acreage is traditionally a mainstay for bees’ summer range and honey production Learn More Here

Beekeepers can give bees a boost by using supplements. Supplemental protein can be used when pollen is not readily available to support brood production. This works for a little while but eventually, a natural pollen source is needed for the colony to remain healthy.

Beekeepers will also supplement colonies with sugar if they need additional energy stores for spring growth or to prepare for winter. Feeding bees is a part of beekeeping, but there is no replacement for natural, diverse blooming plants.

This honey bee is foraging on wild bergamot in a Bee and Butterfly Habitat Fund planting in North Dakota designed to provide high-quality honey bee and pollinator habitat.

Pesticides are chemicals that are used to control unwanted pests. From mosquito and tick repellants to weed killers for lawns, to agricultural chemicals, pesticides are used in the USA and around the world every day for a variety of reasons – some of them lifesaving.

Bees encounter pesticides most often from agricultural use, lawn and garden use, and in-hive products. Beekeepers rely on pesticides to treat Varroa mites and farmers and gardeners rely on pesticides to treat unwanted insects, fungus, and weeds. While insecticides like neonicotinoids are the most widely known pesticides to impact bees and pollinators, other pesticides such as herbicides can have indirect effects by reducing blooming plants that bees need to survive. Even some fungicides may have unintentional effects on honey bee nutrition or may increase toxicity when mixed with other chemicals.

This chart from the Bee Informed Partnership, shows the proportion of pesticides, by target, in wax samples taken from honey bee colonies across the united states. Varroacides make up a large chunk because beekeepers apply these in colonies to control Varroa. Bees encounter fungicides while foraging in cropping systems. Fungicides are often used in almond production and blueberries, which many colonies visit for pollination. Samples to produce this data were collected through the National Honey Bee Disease Survey (USDA, HNBDS) in association with Apiary Inspectors of America and University of Maryland.

When considering pesticide effects on pollinators, scientists and beekeepers must be aware of the lethal effects as well as sub-lethal effects. Sub-lethal effects can include sensory impairment, reduced immune functions, reduced ability to forage, and other damaging but not immediately deadly effects.

The large body of research available is often contradictory, often due to the difficulty reproducing realistic field conditions in the lab and vice versa. More research needs to be conducted to fully understand the full effects of pesticides on honey bees.

Pesticides are part of current agricultural practices, but many groups are working on mitigating risk to honey bees and other non-target insects through the development of communication tools, best management practices, and the use of integrated pest management (IPM).

There are many resources that can be used to learn more about the use of pesticides in the united states, for example, the following tool from the United States Geological Survey, which estimates pesticide use in the United States. Another excellent resource is the California Department of Pesticide Regulation (DPR).