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Bees are essential to healthy, biodiverse ecosystems.
Photo by David Kosling, USDA
While there are native bees in the United States, some of which are managed for commercial production of many high-value and specialty crops, honey bees are more prolific and easier to manage, especially on a commercial level for pollination of a wide variety of crops. Honey bees are a critical link in U.S. agricultural production. About one mouthful in three in our diet directly or indirectly benefits from honey bee pollination. Commercial production of many high-value and specialty crops like almonds and other tree nuts, berries, fruits and vegetables depend on pollination by honey bees. But managed honey bees have come under serious pressures from many different stresses, which has resulted in beekeepers losing many colonies.
USDA’s Agricultural Research Service (ARS) is using innovation and state-of-the-art technologies to enhance overall honey bee health and improve bee management practices. Our main focus is studying honey bee diseases and parasites and how best to control them, how stress levels and climate change conditions affect bee performance, and honey bee biology and genetics. ARS scientists are working on diverse projects and collaborating with agricultural agencies, universities, beekeepers, and industry groups to improve honey bee health and the health of all pollinators.
Together we can keep bees and other pollinators healthy, happy, and buzzing!
ARS is focused on improving the health of managed and wild honey bees by finding ways to mitigate the impacts of pathogens, pests, and pesticides and enhancing bee nutrition and management. Our researchers are also working on projects that take a bigger-picture view toward helping honey bees. This includes developing better knowledge about areas such as gut microbes and their interactions with honey bee immune systems, preservation and expansion of honey bee genetic diversity, and evaluating the effect of land management practices on bees to assure better productivity of pollinators.
Buzz around below to listen, watch, and read about our bee research, and what you can do to help our pollinator friends.
Podcast: The Buzz Around Bees
Ep.1: The State of the Honey Bee
One of the world's leading honey bee experts, ARS entomologist Jay Evans discusses the state of honey bee populations.
Honey bees are facing larger and more diverse threats than ever before. The Four P’s (pathogens, pests, pesticides, and poor nutrition) are longstanding issues, and they are being exasperated by changes in climate conditions, fewer food and water resources, and having to re-establish in new environments. All these factors tend to overlap and interact with one another, which further complicates their survival and productivity. In addition, there are other issues that have impacts on honey bee health, such as the narrow genetic base of honey bees in the United States.
Below are some of the most pressing threats to honey bees and what we’re doing to mitigate these threats.
Parasites and Pests
Varroa mites (Varroa destructor) are essentially a modern honey bee plague. The Varroa mite has been responsible for the deaths of massive numbers of honey bee colonies since its arrival in the United States in 1987. A native of Asia, Varroa normally parasitizes the Asian honey bee, Apis cerana, which is a different species from the European or western honey bee, Apis mellifera, on which this country primarily depends for crop pollination.
Varroa mites directly damage honey bees by attaching and feeding on the fat body of the honey bee. They also indirectly damage honey bees because, similarly to mosquitos, Varroa mites also transmit an array of pathogenic viruses to honey bees such as deformed wing virus.
Beekeepers have identified Varroa mites as their single most serious problem causing colony losses today.
Small hive beetles, native to sub-Saharan Africa, were first found in the United States in 1996 and had spread to 30 States by 2014. Large beetle populations are able to lay enormous numbers of eggs. These eggs develop quickly and result in rapid destruction of unprotected combs in a short time. If large populations of beetles are allowed to build up, even strong colonies can be overwhelmed in a short time.
Wax moths arrived in the United States in 1998 in Florida. This can be a very destructive insect pest, damaging beeswax comb, comb honey, and bee-collected pollen. Wax moths are rarely the initial cause of colony failure but can overcome weak colonies.
Tropilaelaps mites are the most serious parasites of Apis mellifera in Asia. The parasitic mites feed on honey bees and serve as vectors for viral diseases like deformed wing virus (DWV), one of the leading causes of honey bee colony losses. DWV results in the death of immature brood and wing deformities in infested adult bees. Because the introduction of tropilaelaps mites into the United States would be added burden to the beekeeping community USDA's APHIS is monitoring the possible introduction of it into the United States.
Pathogens
Since the 1980s, many new exotic pathogens that infect honey bees have been found in this country. These include deformed wing virus, paralytic viruses such as Israeli acute paralysis virus, which was first found in 2004, European foulbrood bacteria, and Nosema ceranae fungi, which arrived in 2005. They have all become major problems for U.S. honey bees and beekeepers.
Honey bees' natural diet comes primarily from nectar and pollen gathered from a wide variety of flowers. Insufficient or incomplete nutrition has come to be recognized as an essential factor that weakens the honey bee's immune systems and is likely to make bees more susceptible to all of the other problems troubling them today.
As demand for pollination services grows, bee colonies often are kept for more time on sites in a mono-crop environment before being moved directly to the next mono-crop area. As more and more land is lost to urbanization and suburbanization, it also means a loss of habitat with a diverse mix of nutritious bee forage plants. In addition, when it comes to helping bee colonies survive the winter and droughts, both times when nectar supplies can be scarce for bees, beekeepers often provide an artificial diet. Scientists are still trying to perfectly duplicate a bee's natural pollen/nectar diet for those times of the year when good forage is not available.
ARS researchers are looking to perfectly duplicate a bee's natural pollen/nectar diet for those times of the year when good forage is not available. They are also studying different food sources that could provide more nutrition and health benefits for honey bees.
A survey of honey bee colonies conducted in 2010 by ARS researchers looked at 170 pesticides or their residues in honey bees, beeswax, and pollen. The data showed no consistent pattern of pesticide that differed between healthy and Colony Collapse Disorder affected colonies. The most commonly found pesticide in the study was coumaphos, which is used by beekeepers to treat honey bees for Varroa mites.
Photo by Preston Keres, USDA
The pesticide class neonicotinoids (for example, clothianidin, thiamethoxam, and imidacloprid) has been accused of damaging or killing honey bees or being the cause of CCD even when the exposure is below the level expected to be toxic. The nicotine-based neonicotinoids were developed in the mid-1990s in large part because they showed reduced toxicity to wildlife compared with previously used organophosphate and carbamate insecticides.
The scientific data about the impact of pesticides and neonicotinoids in particular at environmentally and agriculturally realistic levels is mixed. Some findings have shown that neonicotinoids have sublethal effects on honey bees at or below approved doses and exposures. Documenting such sublethal effects is very difficult due to the many factors that can influence individual situations in field studies and during grower use including timing of use, health and nutritional state of the bees, total mix of pesticides, pathogens and parasites present, crop type, weather during the growing season, and accumulation of pesticides from year to year. Other studies have indicated that healthy colonies appear not to be impacted.
In October 2006, some beekeepers began reporting losses of 30-90 percent of their hives. While colony losses are not unexpected, especially over the winter, this magnitude of losses was unusually high. Colony Collapse Disorder is specifically define by very low, or no adult honey bees present in a hive but with a live queen and no dead honey bee bodies present. Often there is still honey in the hive, and immature bees (brood) are present. Varroa mites, a virus-transmitting parasite of honey bees, have frequently been found in hives hit by CCD. No scientific cause for CCD has been proven. Most research has pointed to a complex of factors being involved in the cause of CCD, and possibly not all of the same factors or the same factors in the same order are involved in all CCD incidents.
In fact, the number of managed colonies that beekeepers have reported losing specifically from CCD began to wane in 2010 and has continued to drop. But the beekeeping industry continues to report losing a high percentage of their colonies each year to other causes.
ARS researchers work closely with beekeepers to monitor potential instances of CCD and study possible causes of this threat.
Northern Giant Hornet
Photo by Stacy Herron, USDA
Northern giant hornets, Vespa mandarinia, formerly known as the Asian giant hornet, are the largest wasps in the world. At roughly 2 inches in length, this invasive species from Southeast Asia has distinctive markings: a large orange or yellow head and black-and-orange stripes across its body.
Though its native range extends from northern India to East Asia, the hornet has been found in western Washington State as well as Vancouver Island and Langley, Canada and is classified as an invasive species in the United States.
The northern giant hornet is a threat to honey bees in its native territory and could also endanger honey bees in the United States if it becomes established here. Recently, the northern giant hornet was eradicated from the United States. ARS researchers will continue to work with state and local governments to detect any future sightings of the northern giant hornet.
There are over 4,000 species of bees native to the United States, including leafcutter bees, bumble bees, alkali bees, mason bees and blue orchard bees, yet we have little information on the health, distribution, and population trends of most of these species. Several non-native bee species are managed for commercial production of many high-value and specialty crops like almonds and other tree nuts, berries, fruits, and vegetables. Leafcutter and mason bees of the genus Megachile are common members of the North American bee fauna, and many Megachile species are important pollinators of summer flowering crops and native plant species. Bumble bees are important pollinators of crops and wild land plants and are the primary pollinators for crops in greenhouses. While alkali bees, Nomia melanderi, are incredibly efficient pollinators of alfalfa. In Washington state, growers in the Touchet area have been managing alkali bees for over 50 years in bee beds adjacent to alfalfa seed fields.
Latest News On Native Bees
Grass Flowers Something to Buzz About
ARS scientists found a turfgrass that serves as a food source for five types of bees.
Beekeepers: Beekeepers can use best management practices including supplemental feeding in times of nectar/pollen scarcity.
The Logan BeeMail Shelter – a portable unit for managing cavity-nesting agricultural pollinators (James Cane, USDA Pollinating Insect-Biology, Management, Systematics Research Unit)
General Public: The best action the public can take to improve honey bee survival is not to use pesticides indiscriminately. In particular, the public should avoid applying pesticides during mid-day hours, when honey bees are most likely to be out foraging for nectar and pollen on flowering plants. In addition, the public can plant pollinator-friendly plants-plants that are good sources of nectar and pollen such as red clover, foxglove, bee balm, joe-pye weed, and other plants. (For more information, visit www.nappc.org.)
An alfalfa leafcutting bee (Megachile rotundata) on an alfalfa flower. (Photo by Peggy Greb, ARS)
Blue orchard bee on a California five-spot flower. (Photo by Jim Cane, ARS)
The western bumble bee, Bombus occidentalis. (Photo by Stephen Ausmus, ARS)
Hunt’s bumble bee, Bombus huntii, a native to the intermountain west. (Photo by Leah Lewis)
A honey bee being inoculated with Nosema to determine bee infection rates and immune responses.
Honey bee landing on a watermelon flower. (Photo by Stephen Ausmus, ARS)
Sweat bee visiting a dandelion. (Photo by Scott Bauer, ARS)
The blueberry bee, Osmia ribifloris, is an effective pollinator of commercial blueberries and is one of several relatives of the blue orchard bee, Osmia lignaria. (Photo by Jack Dykinga, ARS)
A mustached mud bee, Anthophora abrupta. (Photo by Scott Bauer, ARS)
European honey bee with a Varroa mite on its back. (Photo by Scott Bauer, ARS).
Photo by Lance Cheung, USDA
ARS Bee Research Sites and Resources
Did you know? ARS bee research laboratories are located throughout the United States. Each of the labs focus on a wide range of issues that impact bee health.
Honey Bee Breeding, Genetics, and Physiology Research Lab - Areawide IPM Project dedicated to bees
ARS Grand Challenge Synergy Project - creating pollinator landscapes and overwintering practices to increase pollinator populations in a changing climate.
