Author: Bee Health Collective Staff

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 powerful tools that can be beneficial. Their usage can also have unintended consequences.

Bees encounter pesticides most often from agricultural use, in-hive products like miticides, community mosquito control, landscaping programs, and homeowner lawn and garden use. 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.

Beeswax inside of a colony can easily become contaminated with (and often hangs on to) the various pesticides bees encounter. 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 tend to encounter insecticides and 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. Sublethal effects can be less obvious, and include sensory impairment, reduced immune functions, reduced ability to forage, and other damaging but not immediately deadly effects.

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).

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

Good nutrition helps mitigate other health stressors including Varroa, pesticides, and pathogens, and access to plenty of flowers is essential to honey production. 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 farmed in large areas of land that are heavily treated with agricultural chemicals. 

The above chart, sourced from USDA data, illustrates the growth in corn and soy crops since 1986 along with an overall 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

The Bee and Butterfly Habitat Fund, which has been studied alongside CRP, is a highly effective option for putting pollinator forage on less commercially productive ground. 

When forage isn’t abundant, beekeepers can give bees a boost by using various protein and sugar supplements. Supplemental protein is 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.

Supplemental sugar, usually in syrup form, is given to bees 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.

These commercial beekeepers are using tanks of sugar syrup carried on trucks to feed bee colonies upon arrival in California for almond pollination..

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

Nosema

Nosema disease is widespread, and caused by a single-celled parasite that infects the gut-lining of the bee, causing dysentery and other colony health impacts. 

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)

(Chart Image here-2021 Prevalence of DWV-A)This chart from the Bee Informed Partnership shows the Prevalence of Deformed wing virus (DWV). DWV is closely linked to Vvarroa 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.