Organic Varroa Control

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Organic Varroa Control

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(!! Draft!!)

Why it is important to develop organic varroa control and to get away from chemical treatment is explained under the Veterinary Treatments Section.

Searching the Internet, one will notice that many methods for organic varroa control have been either discovered by chance or developed by researchers. Some methods found during my researches were rather promising, but typically found little echo and few were subject to further investigation and development, leaving their inventors in frustrated isolation. Other methods are rather dubious and may represent risks for bee health and the quality of honey.

This chapter examines the methods known at the moment of the publication of this survey and tries to reveal which hope they represent to get out of the "varroa crisis". This review is a mere listing of known organic treatment with a personal appreciation of the advantages and risks. The author cannot be made liable for any incidents linked with the implementation of these methods – beekeepers may try these methods at their own risks.

If you have a positive or negative experience with one of those methods, have information that contradict the information given here or would like to suggest supplementary useful information, you are invited to share this with me: Please contact me.

Remarks

According to EU Reg.1804/99, beekeepers intending to convert their apiary to an organic exploitation have to substitute all the combs in all beehives with foundations from organic be keeping due to pesticide accumulation in the wax.[1] (See Veterinary Treatments for more information on pest treatment residues in beehives.)

Keep in mind that healthy bees are actually best able to develop defences by themselves against diseases and pests. Therefore, prior to using control methods, beekeepers should as far as possible see to ensure their bees a healthy environment and healthy food and to spare them sources of stress: avoid monocultures and fields treated with pesticides, leave the bees enough stores of food collected by themselves also in the winter, prefer raising local races that are well adapted to the climate, reduce migrations to the minimum, use natural products for the construction of hives, etc.

Overview

The following table offers an overview of the currently known methods for organic varroa control. Click on the corresponding links for each methods to get more details about each methods.

Method Efficiency Risks Practicability Special recommendations Other remarks
Varroa Predators, esp. pseudoscorpions Variable. Studies need to be conducted to find out which conditions support best the presence of these predators in hives. None if local species are bred Easily put in practice with humus or compost heaps at the bottom of beehives. Difficult to apply in the case of migrating beehives, especially if they remain constantly on trucks. The use of chemicals that are likely to harm pseudoscorpions is definitively prohibited with this method.

A combination with bottom screens is not advisable either.

Similarly to ladybirds against aphids in organic agriculture/gardening, pseudoscorpions could be bred by specialised suppliers to provide beekeepers in urgent cases.
PMMA Combs Insufficient data.

May be insufficiently effective since some female varroas are fertilised even before the premature hatching of the young bees. May result in the selection of mites that reproduce earlier, thus end up to be ineffective and even to worsen the problem.

May affect the bees' physiognomy, therefore their behaviour. Presents hygienic problems for brood cells. Low acceptance of plastic combs by bees: the colony has to be forced on them. May interfere with bees communication within the hive. Experimental results are missing. The manipulation in the life cycle of bees and the use of plastic makes this method little recommandable in organic beekeeping.
Drone Combs Up to 95% mite removal, but no definitive remediation. A complementary treatment may be necessary in some cases where environmental conditions add to the difficulties and before the winter May result in selection of varroa mites that breed in female bee larvae cells thus end up to be ineffective and even to worsen the problem.

Destroys large populations of drones, which reduces the chances of proper fecundation of queens, thus threatens the renewal capacities of bee populations.

Wrong timing and the performance of the method on weak colonies can lead to the loss of colonies.

Comb foundations are easily obtained from beekeeping suppliers but may be contaminated by acaricides residues. Make therefore sure that only you own wax is used for the foundation.

The method is very labour-intensive and require a lot of skills and dexterity.

Make a moderate use of this method (no more than 4 frame exchanges in a year) to avoid the depletion of drone population.

Perform the operations only on colonies that are strong enough.

Smoking Up to 100% mite knockdown according to the herbs used. The medicinal herbs have to be chosen very carefully, since some are toxic to bees. Too frequent smoking can disturb the bees' pheromones, thus the organisation of the colony, and contaminate the honey with residues. Easily put in practice with the usual equipment of a beekeeper. Once refined and confirmed, the treatment should be performed by a specially trained vet. As a beekeeper, do not try the method by yourself! The method can be best combined with the bottom screen method. Promotes an intensified grooming behaviour in bees, thus a evolution toward defence mechanisms against varroa in the honeybee.
Inert Dusts Up to 91% mite knockdown under use of confectioner sugar. None reported. Bees affected by varroase may be sensitive to the supplementary stress caused by dusting, which would result in an apparent increased bee mortality due to the treatment. May require special equipment. Should preferably be performed by a specially trained vet.

The method can be best combined with the bottom screen method.

Promotes an intensified grooming behaviour in bees, thus a evolution toward defence mechanisms against varroa in the honeybee.
Bottom Screens Many beekeepers reported apiaries completely free of varroa without complementary treatment using tube screens, though trials in academic context could not confirm their efficiency. No major risk for the bees reported. May increase the opportunities of robbing by bees from other colonies Bottom screens are available from beekeeping suppliers and easily mounted in a hive. The method can be combined with varroa knockdown methods, like smoking or dusting.

The developers mostly recommend leaving the bottom of the hive open, as, according to them, good ventilation results in higher mite fall. Beekeepers in cold climates, like mountain areas, reported increased winter stocks consumption by bees, thus preferred to install a closed bottom, at least for the winter.

Some bee lineages have been observed to have developed a more aggressive grooming behaviour against varroa. The method takes advantage of this evolution and makes it rewarding for the bees.
Hyperthermia Up to 90%, but the treatment has mostly to be complemented with a supplementary treatment. Does not provide definitive remediation, and the remaining varroas can start developping again. Low risks if applied on the imagenes, nevertheless, the brood is more sensitive. Risk of the development of heat-resistant varroas. Laborious. The method requires exact heat and humidity control, which may be difficult with self-made or simple equipment. Apply only in the autumn, since spring treatment have led to development delay or even collapse of colonies. The methods is poorly documented. It needs further testing to establish an acknowledged technique and the production and publication of treatment conditions and equipment specifications. If finally developed to an acknowledged technique, vets should be trained to be able perform this method and assist beekeepers.
Fungi Varroa mortality reached 90% within 4-5 days in laboratory tests. The bees did not show any health alteration after the treatments. They seem to be immune to the fungi at all development stages. Nevertheless, further trials need to confirm the absence of sublethal or other detrimental effects and that the spreading of fungi in the beehive is not detrimental to the quality of bee products for human consumption: If any problem is discovered after dissemination, it will be very difficult to remove the fungi from the environment. Strips offer the same ease of treatment than current chemotherapeutic treatments. Since dead mites are a favourable ground for development of fungi, it is not judicious to use bottom screens together with this method. The strips should be only delivered on prescription by vets in order to prevent inadequate or abusive use of the therapy.
Propolis solutions 100% varroa mortality within 5 s in laboratory conditions. Not experimented in the live environment of a beehive. The available data do not enable to judge if the mortality of the varroa is due to the propolis or the ethanol content of the solutions. The propolis is unlikely to affect badly the bees, but it is necessary to test further how the solutions will behave and might affect bees and brood in direct application in the beehive, especially in consideration of the ethanol content. The description of the suggested manufacture method cannot be performed with the normal equipment of a beekeeper and is very energy-intensive. - The method needs more extended investigation, especially to check if it would be efficient in a beehive environment.
Essential Oils (Analyse under work...) May alter organoleptic properties of honey while national and international laws prohibit taste-altering additives in honey.
Cupric Salts Up to 96.5 %, with a delay of several days due to systemic effect. No toxicity observed in bees, neither in the brood. Residues in honey volitize before the final stage of honey production. Very easy: Administrated to bees as syrup before the winter. Lack of empirical data to confirm the efficiency and innocuousness for bees of this method. Use with care due to the lack of field studies.
Pheromones Traps (Analyse under work...)
Reproduction-Inhibiting Pheromones (Analyse under work...)
The bee races and natural evolution (Analyse under work...)
Bred races (Analyse under work...)

References

  1. Lodesani M., Costa, C, 2008: Residues in beeswax after conversion to organic beekeeping. http://orgprints.org/11602/1/Lodesani_11602_ed.doc




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