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How breeders toughen up honeybees to resist the deadly varroa mites

Varroa mite treatment honey bees

The varroa mites or Varroa destructor is an external parasite that’s endangering the honeybee colonies all over the globe. It was reported to be first seen in North Carolina in 1990. It was only three ago that its existence was made known to the united states. The mite weakens the bees by sucking on their fat bodies and because of their infestation, many honeybee colonies were wiped out. In the state of North Carolina, the recorded loss suggests a loss of 44 per cent of these honeybee colonies ever since the invasion. Hence, this makes it extremely important to understand the biology and workings of the varroa mites along with some effective control measures.

The biology of varroa mites.

Being external parasites, the varroa mites attack both the adult honeybees and their larvae that are still developing. The adult mites are oval and flattened in shape. They have reddish-brown coloring. Dimension wise they are 0.06 inches in width, almost as small as the size of a pinhead. The female mites enter the cell of the developing honeybee larvae to deposit a maximum of 6 eggs inside of it. As the mite develops it feeds on the pupae of the bee. If they are more mites predating on the pupae, more is the chance of the honeybee larvae dying or getting deformed. Sometimes they may not show any visual effects. The female mites of the bee larvae cell die but the male then continues to climb into the adult worker bees to feed on their hemolymph or the bee blood. The same cycle is repeated over and over by the female mites repeatedly. The male mites prefer the drone larvae instead of the worker bee larvae. But both the larvae stand at the danger of infestation is immediate control measures are not taken.

There are many indirect ways in which the mites can harm the honeybees and their colonies. Apart from feeding on the larvae bees and the adult one, these mites are a vector for many kinds of viruses that are fatal for the honeybees. the viral infection weakens the bee’s immune system and makes them prone to a condition known as parasitic mite syndrome which is deadly enough to kill an entire honeybee colony within a few months of infestation.

Methods of varroa mite detection for further varroa mite treatment.

Varroa destructor

Most of the varroa mite infection occurs in the months embarking late summer or fall seasons. It is complex to identify a honeybee colony with an excess of mite invasion. For this reason, it is important that bee sampling is done for the estimation of the extent to which the infestation has spread. There are several different methods through which the estimation can be done. They are as follows:

The sugar shake method: through this technique the mite prevalence in the colony is estimated. Which means the results of the percentage of the adult bees suffering from the infestation are counted. 

The following procedure is followed:

1. a transparent one-pint jar with a lid with 1/8-inch hardware cloth or any other kind of mesh is taken. 

2. 200 adult bees are brushed or shook from a frame with an emerging brood on the inside of the jar or the container

3. the jar lid is closed and 2 or 3 tablespoons of 6x powdered sugar is added through the mesh section of the lid. 

4. the jar or container is set aside for a few minutes to get the bees fully covered with the powdered sugar.

5. the mites are dislodged, if present onto a flattened surface after the jar is shaken a few times. It is important to note that the bees now covered in sugar do not die and can be returned to their colony. It more than ten motes are found per batch of 200 bees, there is an infestation. This means that the necessary measure should be immediately taken. The mites can be viewed in more detail with the help of a magnifying glass. 

The sticky board method: for the estimation of total mite load on the colony or the total number of mites present in the hives.

 Here’s a simple tutorial on how to count the total mite load in a colony:

1. a sticky can easily be purchased from any beekeeping object retailer or company. The board comes with an adhesive material and a grid for sampling purposes. If it is hard to purchase a sticky board in your area, one can do it themselves with a stiff sheet of paper and some sticky material.

2. the upper surface is then sprayed with an aerosol spray or for the homemade board, a very thin layer of petroleum jelly is applied. 

3. the board is placed between two mesh covers so that one mesh is on the top and the other is at the bottom of it. this is done to ensure that the subjected do no stick to the sticky surface of the board.

4. the board is placed on the lower level of the beehive. After a while, a considerable number of mites, if present will begin to fall on the board, sticking to it.

5. the board is extracted after twenty-four hours to count the mite count. In case the number of mites present on the board exceeds the count of 60 or 190 depending on the size of the colony. The necessary control measures are taken.

Using the alcohol wash: this method is quite like the sugar roll method. 

Here is how it’s done in a few simple steps:

1. in a transparent jar measuring a pint, rubbing alcohol is poured up to 2 inches.

2. 200 adult honeybees are brushed in it from a frame with an emerging brood.

3. the container is school vigorously for a minimum span of 30 seconds. The container is then taken in for examination and estimation of the sunken mites at the bottom of the jar. If more than ten mites are found then the bee colony is infested needing immediate measures.

Drone brooding inspection technique: this is a less reliable method. As it cannot give an acute estimation of the mite infestation in the colony. But this is a good enough method to determine the degree of varroa mites present.

1. the drone brood located on the periphery of the hive is selected.

2. cells are uncapped for pupae removal

3. the adult varroa mites if present is closely inspected. In case there is more than 10 per cent of drones than are infested then the colony should be declared infested, needing immediate control.

Борьба с заражением клещами Varroa (рекомендация Homelab Veterinary)

Controlling Varroa mite infestation

Many beekeepers still practice the traditional method of varroa mite control. One of that is to hanging plastic strips covered in pesticide in between beehives. However, these methods have proven to be less and less effective against the infestation over the years. The mites are evolving rapidly and developing resistances against such chemicals and other forms of treatments. There was a need to come up with better and more effective techniques to fight these mites. The methods as mentioned below are either structural or mechanical. Several changes are made to the hives and the resistant stronger mites. Bio pesticide is a very useful weapon against such parasitic attacks, and much more environmentally friendly than using a harmful synthetic material.

Mechanical control

These methods are simply intended to bring some changes to the management methods of the honeybee hives. The main advantage of doing this is that these methods are completely chemical-free and poses no threat to the bees in the hive. Neither do they interrupt the regular process of honey production and collection? These tasks are more labor intensive requiring better equipment.

1. screened bottom boards: this method is proven and tested one. replacing the wooden bottom of the beehive with the screen that’s meshed or any other less solid surface. After using this technique, the studies report a considerable decrease in the number of mites. The complete reason behind remains unclear but it is suggested that better ventilation might the cause of this mite reduction. 

2. drone brood trapping: as mentioned earlier, varroa mites feed on the drone larvae lymph making holes in the pupae of the honeybees. the cause of this is that the drones are relatively larger and take more time to develop. This allows the female mites to lay more eggs inside the larvae. This preference by the mites over drone bee larvae is taken advantage of. Combs with drone sized cells are placed suggestively in the hives. They attract the mites away from the hives. The control drones are then removed after mites emerge from the cells. 

Inert dust: adult mites instead of travelling all over the hive with their phalanges, clinging at the back of the adult bees as transportation means. It is understandable that on covering the bees with any slippery material such as talc powder or powdered sugar will make the clinging mites to lose their grips. This is a labor-intensive technique and causes visible disturbances in the bee colonies. The only advantage being this method is devoid of the use of chemical pesticides. 

Stocks of bees that are tolerant of varroa mites.

Mite treatment for bees

Advancements in biogenetics of honeybees have shown exciting and positive results at creating a batch of bees resistant to varroa mites. Scientists have worked rigorously over the years to develop mite-resistant bees. the complete understanding of this works is still vague but it is believed that the physiological and behavioral changes exhibited by these bees contribute towards their tolerance to these varroa mites. Many strains of bees known today are building mechanisms to drive the mites out of their colonies.

The Russian strain: the USDA honeybee research lab located in Baton Rouge in Louisiana, has imported a very specific Russian strain of honeybees from Primorsky which is the extreme eastern region of Russia. These Russian honeybees are known for their amazing habits of coexisting with the parasitic varroa mites. The specific species showing this biotic relation is a strain of sister honeybees called the Apis cerana. The evolution happed as the bees were exposed to the mites for a very long period which would have helped them to develop some resistance for the mites. Research suggests the Russian bees are two times more resistant than the common commercial species. They also show a considerable amount of resistance to the tracheal mites, even so, the reason behind the phenomenon remains unclear. The stronger strains are now commercially available in many regions of the united states of America after they undergo a special quarantine period.

The VSH stock of honeybees: the artificial insemination and classical breeding techniques have allowed the researchers at USDA to choose a high varroa mite resistant strain of honeybees. the bees are equipped to detect mite infestation in the cells of the developing bee pupae. They can extract the mites even before they develop completely. The stock was crossed with the commercially available bees for the integration of the stronger trains into different strains lacking it. 

Biopesticides: 

Can be defined as the resistant method naturally present in some strains of bees or the by-products. Many of which have proved to be useful in controlling varroa mite infestation. These pesticides are as efficient as their chemical synthetic counterparts. But these biopesticides have different production and action periods. This is an important topic of research for many bee sustenance and improvement laboratories globally. 

1.Apilife VAR®, is a combination of essential oils such as thymol, eucalyptol and menthol. The product was approved by the US environment protection agency or EPA. The state of North Carolina has been using the product ever since to control infestation from both varroa destructor and tracheal mites. This product is proven to be 97 per cent effective for causing mite death. The product comes in the form of a vermiculite tablet. The tablet is broken into four pieces to be placed in all the four areas of a beehive. The pieces are wrapped with mesh material to prevent the chances of the bees chewing them. The tablets are used every week for a total period of three weeks. The tablet’s functions at a very specific temperature ranges of 60 degrees to 90-degrees. the product can also be fatal for the bees hence it is best to use during the fall season which has the minimum amount of brooding activity. Apilife VAR®. is an organic form of pesticide however there are some restrictions on its use. It can only be purchased by people who own the NC pesticide applicators license.

2. Formic acid: after the permission was granted by the EPA to use formic acid to control varroa mite infestation in bee colonies, this method has become popular among the breeders belonging to Canada or the united states of America. There different ways of using this organic pesticide, such as pads soaked in liquid formic acid. It is advised to not use the product during honey production. Formic acid to be useful needs to have a specific temperature range between 50 degrees to 79-degrees. small colonies are often seen to be overwhelmed by the formic acid fumes. The product is highly corrosive to human beings, hence appropriate care should be taken during its application.

Chemical treatments with synthetic pesticides. 

This is a traditional method of controlling varroa mite infestation is colonies of honeybees. these are truly very effective to help decrease the count of motes but there are chances that the mites can develop resistance towards such chemicals. 

1. Amitraz Plus Strips: a comparatively new product in the market of pesticides. It used the chemical called amitraz to practice mite control in beehives. It works similarly as its fellow counterpart apistan.

honey bee mite treatment Amitraz
Amitraz strips

2.Apistan®.is one of the earliest pesticides to be used for this purpose and it is registered as a by the EPA for varroa mite control. The chemical was sold in strips of plastic containing active pesticide. The strips are then hung so that they are in between two hive frames outside of the brooding nest. The product is a very strong pesticide and can get rid of varroa mites with 100 per cent effectivity of used with care. 

Apistan

3.Checkmite+®. This falls under the section 18 emergency category of pesticide for mite control. Quite like apistan, it comes in a plastic bag. There have been registered cases of mites developing against such products.

varroa mite treatment bayer

4. Amipol T (amitraz and thymol) is a honey bee treatment made specially to treat against Varroa Mites and the diseases they carry. This treatment is effectively carried out in the spring and autumn months when there is no brood and in bee colonies.

5. Antivaro Strips flumethrin (Flumethrinum) destroys up to 99.9% of all ticks in the hive. – The preparation is a thin wood strip impregnated with an active substance flumethrinum. – Flumetrin is a synthetic pyrethroid with a contact acaricidal effect against the Varroa destructor (formerly Varroa jacobsoni), which does not have harmful effects on bees, queens, larvae.

6. Oxalic acid, however, is entirely natural. It is an organic compound found in nature within many plants, including vegetables, leafy greens, fruits, nuts, seeds and more. Herbivores find oxalic acid repellent, which is a handy property if you are a plant!

Summary

1. varroa mites is a strain of species that now poses one of the greatest threats to the beekeepers and their honeybee colonies. These colonies if infested for a long period can wipe entire colonies. 

2. beekeepers should be vigilant and conduct regular checkups of their beehives to estimate a load of varroa mites in their colonies. This helps them decide when to take the required measures to prevent the Imminent death of their honeybees.

3. using a chemical product for a long period can cause the parasite to develop resistance towards it. hence, using different products for some time can prevent them from getting resistance.

4. making use of chemicals that are not approved by responsible institutions should strictly not be used, as they may fire back and cause the death of honeybees in the colonies they are being used at. 

5. understanding that chemical pesticides pose inherent risks to the bees and their hives is important. Hence, there are regulations which state that only those individuals who own some specific certifications can be trusted to handle such chemicals and put them to use. Hence, interested beekeepers should receive the necessary training through the NCDA and CS pesticide licensing program.

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