The best way to control the varroa without harming the bees

Varroa, for beekeepers, means huge population losses and a drop in the profitability of their farms. Beekeepers have to control the varroa to avoid running out of bees. Current acaricides have been used to control varroa, but this mite is becoming increasingly resistant to these products and the search for other, more efficient methods is essential.

Summary: Varroa is a problem that decimates almost all bees in the world. In Spain all bees have to be treated against varroa, otherwise they will disappear. Recently they are testing a new method which does not use chemicals. Also, in our shop in Las Rozas de Madrid we offer you information about  honey, royal jelly, pollen and propolis.

Other interesting articles: Bees, their honey and curiosities

1. New method to control varroa

A group of scientists at the University of Sussex in the UK have determined the best way to control varroa mites without harming them. Varroa is one of the biggest threats to bees, and the real headache for honey producers.

The Beekeeping and Social Insects Laboratory (LASI) team has analyzed the dose and the most convenient method to treat beehives with oxalic acid. Oxalic acid is a natural element that is present in nature. Furthermore, it is the most used by beekeepers to treat this mite.

a) Published in the magazine: Journal of Beekeeping research

This study was published on January 5, 2016 in the Journal of Beekeeping and Honey Research. This study has shown that two of the three methods commonly used by beekeepers for the treatment of varroa using oxalic acid cause damage to honey bees. Consequently, they result in a lower survival rate of honey bees over the winter.

However, the method that uses sublimation to spread the product by vaporizing it in the hive, using a small electric radiator, has no harmful effects on the beehive. Colonies treated in this way had 20 percent more honey bees after four months than hives not treated with this method.

This sublimation method is much easier to use. Furhtermore, it causes increased mortality in varroa mites, killing 97 percent of them with one application and lower doses than the other two methods. Therefore, this is the best method to treat varroa

Professor Francis Ratrieks, head of this beekeeping and honey laboratory, said in his research that beekeepers should stop using the other two methods for the application of oxalic acid, drip and atomization, because these two methods are more harmful to bees and less effective in eliminating varroa.

Professor Ratrieks also added that the sublimation method is too good to be true, reconfirming that this method with oxalic acid is the best treatment that honey beekeepers can use to kill varroa, as it has no harmful effects on bees, and is the fastest and easiest to use.

b) Varroa, a big problem for honey bees

Varroa causes enormous damage to honey bees, directly by feeding on their blood and indirectly, transmitting viral diseases such as the deformed wing virus.

Control of the varroa with oxalic acid and using the sublimation method is capable of killing 99 percent of the varroa in the hive. However, the current problem is that the varroa is becoming resistant to these treatments. In addition, the varroa eggs inside the cells, where the bee pupae are, are not killed with this oxalic acid treatment.

2. Working method

Precious research had shown that oxalic acid kills varroa, but no one had so far compared the mortality of varroa and the damage caused to honey bees with different use doses and application methods, nor had the efficiency of these methods been quantified.

The research was conducted by the Institute of Beekeeping and Honey, LASI, which was funded by the Esmée Fairbaim Foundation and the honey equipment company, Rowse Honey Ltd, to learn about saving bees from extinction and to learn more about these treatments.

For this study 110 beehives were used in Sussex, UK in the winter of 2012/13 and another 90 in the winter of 2013/14.

The hives that were analyzed did not contain breeding chambers, as is naturally the case in winter, as no new bees are born in winter.

Varroa is found mainly in two parts of the hive. First, in the closed cells of the brood hives, where the bee pulps are found. Here female varroa mites lay their eggs, and these develop by feeding on the blood of the bee pupa at birth. The other area where the varroa is found is hung on the back of the working adult bee. Therefore, oxalic acid can only kill the varroa that is attached to working bees. Consequently, it has no effect on the eggs in the cells of the bee pupae.

a) Results

The three methods of application of oxalic acid commonly used by honey beekeepers were compared in this research. The first method is the sublimation method, in which the oxalic acid crystals were vaporized using a special heater inserted in the entrance of the hive. The second is the drip method, in which the lid of the hive is moved and a solution of oxalic acid is poured over the bees. Finally and last compared method was the atomization method, which consists of spraying all the hives, except the brood chambers.

The doses used were 0.56, 1.125 and 2.25 grams per hive, plus one additional dose per sublimation per hive.

The calculation of the efficiency of the three methods was calculated by removing the varroa mites from a sample of approximately 300 working bees,. Later is taken immediately before treatment and again two weeks later. Those mites were removed with a jet of water and then counted.

They also investigated the possible harmful effects of oxalic acid on honey bees. The investigation also include the number of bees killed in each type of treatment and the state of health after 4 months of treatment.

The project was directed by the master student Hasan Al Toufailia, whose master’s degree was financed by the University of Damascus, Also, by Professor Ratmieks with the assistance of the beekeeping technician and honey and bee expert, Luciano Scandian.

3. Methyl benzoate, another method to control the varroa

Another research conducted by research chemist Zhang is investigating whether low doses of methyl benzoate, a derivative of benzoic acid and methanol. These could be effective in the fight against the varroa mite. Furthermore, it is wreaking havoc on the world’s bees and the quality raw honey industry.

Aijun Zhang is a researcher working for the US Agriculture Research Service, ARS. He recently discovered that the chemical fragrance methyl benzoate could kill these mites and others. This chemical fragance is currently a popular ingredient approved by the US Food and Drug Administration for use in food, cosmetics and shampoo,

Zhang noted that the scent of petunias and other wild plants such as snapdragon release substances that have the ability to attract pollinators. According to him, this scent could be useful for controlling pests in an environmentally friendly way. Pests such as the invasive spotted wing fly, halyomorpha halys and other insects.

The spotted wing fly is a new invasive species that can attack a large number of wild and cultivated fruits that have spread throughout the Americas and many European countries. Halyomorpha halys is another insect brought from Asia. this insect is also causing extensive damage in countries where it has been accidentally introduced.

Zhang works in the laboratory of invasive insect biocontrol and behavioural understanding in Beltsville, Maryland in the United States. He highlights the possibilities he sees in developing a new environmentally friendly pesticide that is based primarily on a chemical compound that is inexpensive to manufacture and rapidly disintegrates under normal environmental conditions.

Recently, Zhang has been granted a patent for the use and research of the methyl benzoate-based pesticide. The Agriculture Research Service, ARS is looking for a company to fund the development of a technology that will produce these pesticides. Later, to be able to bring them to market.

a) Ability to attract fruit flies

Before the research began, Zhang identified volatile compounds in apple juice that had the ability to attract fruit flies. Compounds found in rotting apples and other decaying fruit attract fruit flies. He found that this compound, which he called number 19, strongly repelled the spotted wing fly. Later he also found that this compound killed them. After analysing this compound in the laboratory, which he called compound number 19, he discovered that it was methyl benzoate. A compound with its own characteristic itchy, fruity and floral aroma.

It has been shown that methyl benzoate can be 5 to 20 times more toxic to the eggs of the mancave wing fly, xylostella. Also, more than manduca sexta than conventional insecticides using pyrethroids, a sulphur, pyrethrin mixture, or some other environmentally friendly product on the market today.

Zhang’s next steps will be to test the effectiveness of methyl benzoate against mosquitoes, fire ants, limantria dispar and other insects that attack stored products. In addition, all these insects are developing resistance to common pesticides. For this reason, there is an urgent need to find new methods to control them.

The varroa problem in honey bees is serious. New methods and systems for extermination are becoming known. However, it is clear that at the moment there is no natural method that is truly effective. Let us hope that the private and public sectors will soon find a solution. As the consequences on ecosystems are already beginning to be felt.

Source:

Blog of the University of Sussex, in the United Kingdom

.Scientists determine how to control parasite without harming bees.