What Is the Best Way to Kill Mites on Bees

John Ambrose
Extension Apiculturist
Entomology

David Tarpy
Professor and Extension Apiculturist
Entomology

Joshua Summers
Entomology

Article reprinted with permission from Due north Carolina State Extension Apiculture Program.

Introduction

The varroa mite (Varroa destructor) is the most serious pest of dearest bee colonies worldwide. This parasite was first detected in North Carolina in 1990, having been introduced to the United states of america just 3 years earlier. Virtually all feral (or "wild") honey bee colonies accept all but been wiped out by these mites, and beekeepers keep to struggle with varroa infestations in their hives. In North Carolina solitary, the number of managed beehives has dropped by an estimated 44 percent since the invasion of the mites. It is vital, therefore, to understand the varroa mite and the options available for its control.

Mite biological science

The mite is an external parasite which attacks both adult bees and the developing honey bee larvae. The developed mites have a flattened oval shape, are reddish-brownish in color, and are most 0.06 inches wide (about the size of the head of a pivot). The mated female person mite enters the jail cell of a developing bee larva and lays up to 6 eggs. The developing mites feed on the pupae and, depending on the number of mites, may kill it, cause it to be plain-featured, or accept no visible effect. While the males die in the prison cell, the adult daughter mites climb onto an developed worker bee and feed on its hemolymph (bee "blood"). The female person mite can and so repeat the cycle past entering cells of other developing larvae. Mites adopt drone larvae over worker larvae, only they volition infest worker larvae and eventually impale the colony if preventative measures are not taken.

The mites can harm the bees indirectly likewise. In addition to the obvious furnishings of mites feeding on developing and developed bees, the mites tin can also serve equally vectors of several viruses that tin can kill bees. These secondary infections, facilitated past the mites compromising the bees' allowed systems, tin cause a condition known as Parasitic Mite Syndrome (PMS), which can kill colonies within months of infestation.

Detection methods

Many colonies that succumb to varroa infestations will do so in the late summer or fall. Information technology is difficult to simply inspect a colony and determine if it has a high level of mites. It is important, therefore, to sample bee hives to estimate the degree of infestation.

Sugar Shake Method. This method estimates the mite prevalence within the colony (the per centum of adult bees with mites).

1. Obtain a articulate 1-pint jar or other container with a hat fabricated from ane⁄8-inch hardware cloth or like mesh material. If yous can't find a jar with a mesh hat, make a mesh hat for your container.
2. Castor or shake approximately 200 adult bees from a frame with emerging brood into the jar.
3. Shut the mesh lid on the jar and add ii to three tablespoons of 6x powdered sugar through the hat.
4. Set the jar bated for several minutes to allow the bees (and mites) to be covered in carbohydrate.
5. Shake the sugar (and dislodged mites) out of the jar onto clean, flat surface (preferably white). The bees, although covered in carbohydrate, are not killed and can be returned to the colony. If x or more than mites are found per 200 bees, and then advisable measures should be taken to control the mite population. A magnifying drinking glass may be necessary to run across the mites.

Gluey Lath Method. This method estimates the full mite load of the colony (full number of mites in the hive).

1. Purchase a commercial sticky board from a beekeeping supply company, which has a pre-applied adhesive and sampling grid fatigued on the surface. Alternatively, mucilaginous boards may exist constructed by placing a strong sheet of white paper.
2. Spray the upper surface of the newspaper (facing the bees) with an droplets cooking spray, or employ a thin layer of petroleum jelly to the upper surface of the paper to create a homemade sticky lath.
3. Delight the lath or paper between two 8-mesh wire covers (with ane cover on the top and one on the bottom) so that the bees practice not adhere to the sticky surface.
4. Identify the sticky board on the bottom flooring of the hive. A portion of the mites volition fall off the bees, autumn through the the mesh screen and stick to the white board.
5. Remove the lath 24 hours subsequently and count the full number of mites on information technology. If the number of mites is between 60 and 190 (depending on the size of the colony), then appropriate command measures should be taken.

Alcohol Wash Method. Similar to the sugar scroll, this method requires that the apiculturist brush or shake developed bees into a clear container to measure the prevalence of varroa mites.

1. Pour 1 to 2 inches of rubbing booze (isopropyl alcohol) into a clear ane-pint jar or container with a solid lid.
2. Brush or milkshake approximately 200 developed bees from a frame with emerging brood into the container.
3. Vigorously shake the container for at to the lowest degree 30 seconds, and then examine the container for dead mites sinking to the lesser. If y'all come across 10 or more mites per 200 bees, then you should treat the colony.

Drone Brood Inspection. Considering of the variation in sampling, this method is not always a reliable indicator of mite levels in a colony. All the same, information technology can be used to verify the relative degree of varroa infestation.

1. Detect any capped drone brood inside the hive, which is typically located on the periphery of the brood nest.
2. Uncap the cells and gently remove the pupae.
3. Closely audit the drone pupae for adult varroa mites. If 10 percent or more of the drones are infested, then y'all should accept appropriate measures to reduce the mite population.

Current recommendations are to monitor all honey bee colonies for varroa mite infestation, preferably numerous times over the form of a flavor, to decide if and when treatment is necessary. Information technology is also recommended that multiple sampling techniques are employed to make sure that an accurate measure is obtained for each hive.

Size comparing of a varroa mite.

The varroa mite, Varroa destructor, the most insidious pest of love bee colonies

Carbohydrate-shake step 1

Sugar-shake step 2 in estimating mite levels

The gluey board method in estimating mite load.

Controlling Varroa Mites

Traditional methods for varroa mite command have been to hang plastic strips impregnated with chemical pesticides betwixt the wax combs of bee hives (encounter beneath). Unfortunately, and perhaps inevitably, the mites are rapidly developing resistances to many of the mutual treatments, which has prompted researchers to develop numerous alternative methods to prevent and treat varroa mite infestations. These methods range from structural or mechanical changes to bee hives, to new stocks that are more tolerant of mites, to new bio-pesticides that are valuable alternatives to the standard synthetic treatments.

Mechanical control

Certain control methods involve changes in the direction practices of apiculture. The do good of such mechanical control measures is that they do not apply chemicals to reduce mite levels, thus they may exist employed even during times when the bees are collecting and producing honey. They may, nonetheless, be more laborious or require new equipment, and they may not be as effective as other command measures.

Screened bottom boards. Research has shown some do good of replacing the wooden bottom of a standard bee hive with a wire-mesh screen or other not-solid surface. Several studies have shown numerical decreases in mite levels of colonies using screened bottoms compared to solid bottoms. While the reasons for this decrease is unknown, it may exist due to improve hive ventilation or to the loss of mites inadvertently dropping through the flooring of the hive. The benefits of bottom screens are minimal, however, and unremarkably crave boosted methods of treatment.

Drone-brood trapping. Varroa mites adopt to infest drone breed, which are the developing pupae of male person love bees. This is because drones are larger and take longer to develop, so that female person mites can produce more offspring per generation. Beekeepers may take advantage of this preference by placing special combs with drone-sized cells in their hives to attract mites to the brood. These combs can then be removed earlier the drones—and the mites—sally from their cells. Depending on the time of year, this do tin dramatically reduce the mite populations within colonies.

Inert dusts. Adult mites move through the hive by clinging to the backs of adult bees. Some research has shown that roofing all the adults in a colony with fine dust particles, such every bit powdered saccharide or talc, can cause the mites to lose their grips and fall off their hosts. This technique can be laborious and quite disruptive to a colony, only it requires no chemical pesticides.

Mite-tolerant stocks

Some of the more than exciting advances in varroa mite control has been in honey bee genetics. In recent years, much work has been done with the development of particular strains of honey bees that have shown tolerance to the varroa mite. Though the mechanisms are not completely understood, some behavioral and physiological traits likely play a role in varroa resistance. Today, several strains of bees are bachelor that have been shown to reduce the number of varroa mites within their colonies.

Russian strain. Researchers at the USDA Love Bee Research Lab in Billy Rouge, Louisiana have imported bees from the Primorsky region in far-eastern Russia because they co-exist with the original host species of varroa (the sister honey-bee species, Apis cerana). Because these Russian bees have been exposed to the mite for a longer flow compared to other strains, it follows that they may have developed a resistance to the mite. Indeed, research has shown that they are over twice as resistant to varroa as other commercial stocks. Moreover, for reasons that are even so unclear, this stock appears to be highly resistant to the tracheal mites, a second parasitic mite that infests honey bee colonies. The Russian strain has been made available for commercial purchase in the U.S. afterward a protracted menses in quarantine.

VSH stock. Continuing for Varroa Sensitive Hygiene, this trait was selected for by USDA researchers using classical bee breeding and instrumental insemination techniques. The bees have been selected to find varroa mites in the cells of developing pupae and remove them before the mites tin can reproduce. This stock has been crossed with other, more common commercial stocks in an endeavour to integrate this useful trait into other bee strains.

Hygienic behavior. Many queen breeders have actively bred for colony brood-nest "cleanliness" or hygienic beliefs. Much research has demonstrated lower levels of numerous diseases in colonies selectively bred to uncap and removed diseased or parasitized brood (e.grand., the Minnesota Hygienic stock). While these stocks are not immune to varroa parasitism, they may significantly reduce the need for other control methods.

Bio-pesticides

Biopesticides are defined as naturally occurring organisms or their by-products, and several have been registered for decision-making varroa mites in honey bee colonies. The efficacy of many biopesticides can equal to that of conventional chemical pesticides. However, the delivery of these chemicals can exist quite different, and understanding these differences is important to insure successful control of varroa.

Apilife VAR®. This product—containing a combination of the essential oils thymol, eucalyptol, and menthol—has been approved by the Us Environmental Protection Agency (EPA) for its utilize in Northward Carolina to treat both varroa and tracheal mites. Several studies take shown between 65% and 97% effectiveness at killing varroa mites. The delivery medium of this production is a vermiculite tablet, which must be broken into 4 pieces and placed in the four corners of the hive between the breed chambers. Each section must be wrapped in wire mesh to prevent the bees from chewing it and removing it from the hive prematurely. New tablets must exist used every week for three weeks for consummate effectiveness. The effectiveness of Apilife VAR® is temperature dependent and tin only be used finer in temperatures to a higher place lx°F and below 90°F. The product may cause meaning mortality of bee breed, thus it may be most useful as a fall treatment when brood rearing naturally declines. Though Apilife VAR® is considered an organic pesticide, it is a restricted-use chemical and tin only be purchased and practical by those individuals who have a valid NC Pesticide Applicators License.

Formic acid. The EPA has recently permitted the utilise of formic acid for the control of varroa mites in the Us. This method has been used by beekeepers in Canada and Europe for many years, and it is the but chemical pesticide that tin be used for organic love production. There are several delivery methods for formic acid, such as placing pads soaked with liquid formic acid on meridian of the hive (by the trade proper noun Mite-Abroad II®). The product cannot be used during a honey flow, and the daily high temperatures must be between 50°F and 79°F. If temperatures exceed 82°F during the get-go calendar week of treatment, it must be removed from the hive as it may upshot in a meaning loss of breed and adult bees. Pocket-sized colonies (fewer than vi-20 frames of bees) can themselves be overwhelmed by the fumes. Care must likewise be taken by the beekeeper while applying formic acid, as it is highly corrosive and poisonous to humans, thus proper precautions must be taken to avert exposure.

Chemical (Constructed Pesticide) Treatments

Conventional means of varroa command involve constructed pesticides being administered to a colony by placing plastic strips impregnated with the active chemical within the hive. While these treatments have traditionally provided very loftier levels of control, there is an increasing prevalence of resistance to these chemicals which makes them less reliable in some areas.

Apistan®. One of the first pesticides to be registered by the EPA for the command of varroa mites was Apistan®, the trade proper noun for fluvalinate (a constructed pyrethroid). It is sold as a plastic strip impregnated with the active pesticide, and the strips are hung betwixt the frames of a hive but outside of the brood nest. Fluvalinate is a contact pesticide and provides up to 100% control of varroa mites when properly used. In recent years, nonetheless, there has been increasing reports of varroa mites developing resistance to this pesticide. Information technology is highly recommended, therefore, that Apistan® exist rotated with other treatments to reduce the development of resistance to chemical command past the mites and to ensure its efficacy.

Apivar®. Using the chemical amitraz, this is a relatively new product available to beekeepers for mite control. It works in much the same way as Apistan®, but the mites take non yet developed a resistance.

Checkmite+®. Largely in response to fluvalinate resistance, the EPA registered some other synthetic chemical every bit a Section eighteen emergency-utilize pesticide for varroa control. Checkmite+®, the trade name for coumaphos, is too sold as a plastic strip impregnated with the active pesticide that, when the bees and mites into contact with it, tin provide upward to 100% control when used properly. Coumaphos is a fellow member of the organophosphate grouping of pesticides, and residues can accumulate in wax and be harmful to bees at loftier levels. Just equally with Apistan®, there take been documented cases of varroa mites developing resistance to this pesticide, and then it is important to employ it according to label directions and to alternate its use with other approved treatments. Checkmite+® is also registered for the control of the small hive beetle (Athena tumida), and its sale in North Carolina is restricted to those individuals who have a valid NC Pesticide Applicators License.

Apilife VAR

Administering chemical pesticides

Summary

1. Varroa mites are currently the greatest threat to beekeepers and their colonies, and infested colonies will probably perish if action is non taken to control mite levels. Thus, they are a pregnant threat to a beekeeper's income and satisfaction.
2. Monitoring hives for mite levels enable beekeepers to determine whether treatment is necessary and to make informed decisions about when to take action.
3. The exclusive and continual use of one chemical production is more than probable to effect in the evolution of resistance by the pest. Several different products should exist used on a rotating basis.
4. Do Not, under any circumstances, experiment with non-approved chemic treatments. Such practices are illegal and may result in bee death, the contamination of honey and wax, and severe damage to the beekeeper.
5. Because of the inherent risks with the use of chemical pesticides, and the fact that some of the available treatments tin can merely be obtained by individuals with a current pesticide certification, it is recommended that all beekeepers receive grooming and certification through the NCDA&CS Pesticide Licensing Program.
6. For boosted information or assistance, contact your local NCDA&CS bee inspector, your local county Cooperative Extension middle, or the Apicultural Program at NCSU.

Table 1. Direction practices for varroa mites in honey beehives.

Management Method	Chemic (if applicable)	Relative Effectiveness	Degree of Manipulation	Other Pests Controlled	License Required
Screened bottom board	-	Low	Low	-	-
Drone brood trapping	-	Moderate	Moderate	-	-
Inert dusts	-	Moderate	High	-	-
Mite-tolerant stocks	-	Moderate	Low	TM‡	-
Apilife VAR®	Thymol	Moderate-High	Moderate	TM	Yes
Sucrocide®	Sucrose octanoate	Moderate-Loftier	High	-	-
Mite-Away Ii®	Formic acid	High	Moderate	TM	-
Apistan®	Fluvalinate	High*	Low	-	-
CheckMite+®	Coumaphos	High*	Depression	SHB	Yes
* In areas where resistance has not adult; TM = tracheal mite; SHB = small hive protrude ‡ For Russian strain just

Ths project received support from the Golden Leaf Foundation.

Contact Information

North Carolina Department of Agronomics & Consumer Services, Apiary Inspection

North Carolina State Academy Apiculture Program

For more information on beekeeping, visit the Beekeeping Notes website.

David R. Tarpy Professor and Extension Apiculturist Section of Entomology, Campus Box 7613 Due north Carolina State University Raleigh, NC 27695-7613 TEL: (919) 515-1660 FAX: (919) 515-7746 EMAIL: david_tarpy@ncsu.edu

Jennifer J. Keller Beekeeping Technician Department of Entomology, Campus Box 7613 Due north Carolina Country University Raleigh, NC 27695-7613 TEL: (919) 513-7702 FAX: (919) 515-7746 EMAIL: jennifer_keller@ncsu.edu

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Source: https://www.extension.iastate.edu/smallfarms/managing-varroa-mites-honey-bee-colonies

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