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Perizin, a coumaphos (coumafos) based varroa treatment

This product is not registered for use in the U.K.

General note on chemicals: I do not endorse or advise on chemical treatments, as I am not qualified to do so and there may be dangers beyond my control. New products may be introduced or existing ones withdrawn, so it is difficult to keep up with current information on a website such as this. As many of the chemical pages were generated by Dave Cushman, I am leaving the content mainly as left by Dave for historical purposes only, which may mean information is out of date and unreliable. The user should seek guidance from other sources and satisfy themselves regarding safety and legality. Roger Patterson.

Perizin in 10 ml bottle Perizin is a systemic thysophosphate in the category - ectoparasiticides and is biologically distributed by trophallaxis throughout the colony, the acaricide passes into the haemolymph of the bees and kills the mites feeding on them.

Perizin can be used for both diagnosis and treatment of Varroasis... For diagnosis one treatment is sufficient. For control, two treatments at an interval of seven days are required.

Chemical Name O-(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl) O,O-diethyl phosphorothioate.

Molecular structure of Coumaphos. Coumaphos Molecule

CAS No 56-72-4

Perizin is applied at a 49:1 dilution in distilled water, this dilution being made just before application. The emulsion so formed is dripped evenly along the occupied seams of bees, using an applicator sold for the purpose.

Full sized colonies receive 50 ml of the emulsion per treatment. Developing colonies and colonies that only fill half the box receive half of that dose, i.e. 25 ml. Nuclei, and artificial swarms are treated with 10 to 25 ml pro-rata depending on their strength.

Two methods of mixing are described in the German instruction leaflet, the first uses the whole 10 ml bottle of concentrate and is then made up to 500 ml using the bottom portion of the plastic applicator. The second method is the preparation of a single or small numbers of doses, by dripping one ml per dose from an eye dropper into the bottom portion of the plastic applicator and making up with water until the volume equals 50 ml per dose. Both of these methods are illustrated at right.

Perizin is very effective against varroa mites on adult bees. It is applied to clustering bees when there is no brood present. This late autumn or winter application can cause chilling of the bees so it is usually applied slightly warmed (luke warm = 10°C - 15°C).

The bees are not dosed completely evenly so some bees will succumb to overdose. Bee mortality is low at between 4% and 7%, some of these deaths will be due to direct overdose and some bees that are already weakened will also die even though they may not have received an overdose.

small doses of concentrate applied using an eye dropper into applicator base unit

contents of bottle being emptied into applicator base unit

The Perizin applicator consists of a flexible plastic storage bottle that contains up to 500 ml of diluted 'working solution' and a calibrated tank or 'dosing beaker' that can be filled with the dose required and then delivered via a nozzle on the extreme top of the applicator.

The assembly of the nozzle and installation of the filling stalk is shown in the leftmost illustration, this unit is then screwed to the mouth of the main storage bottle (as shown in the middle image) and the right most picture shows how the required dose is forced from the reservoir at the base, into the top portion (dosing beaker) by squeezing the plastic bottle.

The dose that is contained in the calibrated dosing beaker at the top is then available for delivery by inverting the whole applicator and pouring the solution from the nozzle.

tank unit being screwed to applicator base unit

liquid from base unit is forced into upper storage tank by squeezing

The package that contains the concentrate is illustrated at extreme right.

Once the correct dose has been loaded into the dosing beaker it can be poured in a smooth stream along all seams that are occupied by bees.

The applicator can be used as a means of delivering other substances (oxalic acid) that are used during winter to treat honey bee colonies.

dose being poured along seams of bees

Perizin packaging

Residues... Perizin is a non volatile, fat soluble substance and can migrate from wax into stored honey. Residues are a major problem for Perizin applied as a winter dribble which leaves residues in hive woodwork as well as some residue in wax and honey. Perizin is so soluble in lipids that all wax particles and comb fragments should be removed from honey that is offered for sale.

There is some variability in the systemic activity of Perizin, since it is not significantly distributed between bees on a colony by food exchange between bees, and only occurred in the haemolymph of bees for a maximum period of 12 hours after ingestion.

Coumaphos solutions are effective treatment for varroasis, with rates lethality of mites between 88% and 99%.
Adverse Effects... Perizin was assessed as having a low toxicity for bees (LD50: bee = 14.39µg).

Operator Safety... Coumaphos is highly toxic orally to humans, and has moderate dermal toxicity. However, the low dose formulation of Perizin greatly reduces the danger to the beekeeper.
LD50: Rats - 13-41mg/kg (oral); 860mg/kg(dermal).

Estimated time necessary for application has been determined at 4 minutes per hive per visit for liquid products.
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Dave Cushman.

Originally written by Dave Cushman. Edited and additions by Roger Patterson.

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Page updated 12/12/2022