Icing sugar method
The powdered sugar method or powdered sugar method is a bee-friendly form of bee sample to determine the degree of varroa mite infestation in honey bees.
A certain number of adult honey bees is dusted with powdered sugar, which means that the female varroa mites that sit on it lose their grip and can be sieved and counted by the bees together with the powdered sugar. The bees are not killed in this form of diagnosis and can be returned to the colony.
history
Since the 1990s, bees have been powdered with various types of dust at various bee institutes to obtain living Varroa mites for research. The function of the apotles (adhesive structures) on the legs of the varroa mites is so severely impaired by fine dust that the varroa mites lose their grip on the honeybees' chitin shell. A wide variety of dusts were used for this, including cat litter (bentonite), stone meal, talc and eggshells. However, these foreign substances had harmful effects on the bees.
In 2011, the German Institute for Apiculture in Kirchhain presented the bee sample with powdered sugar as a new, bee-friendly Varroa infestation measurement.
Procedure
For the powdered sugar method, the beekeeper needs a shaker (750 ml) with a measuring cup (100 ml), a clean plastic wrap, a white plastic container with water and of course powdered sugar.
On a dry day, adult bees are removed from the honeycomb or from a non-incubated edge honeycomb and repelled over the plastic film. The film is quickly folded in half so that the bees do not fly away, and the folded edge is pushed open. The bees can be filled into the measuring cup, whereby 100 ml of bee mass corresponds to 50 grams or 500 bees.
For an even more precise infestation measurement, the beekeeper weighs the live bees in a shaker without powdered sugar and calculates the exact degree of infestation (mites per 10 grams of bees) after powdering.
The bees from the measuring cup are filled into the shaking cup and this is closed with the sieve lid. After the beekeeper has filled half a measuring beaker or 35 grams of dry powdered sugar through the sieve lid into the shaker, the shaker is gently shaken three times for three minutes.
Then the powdered sugar is shaken out through the sieve lid directly into the white plastic jar filled with water. Because the powdered sugar dissolves immediately, Varroa mites can be counted well in the water. The bees survive the procedure well and are returned to the colony via the honeycomb legs, where they are cleaned by workers.
Determination of the damage threshold
The damage threshold of Varroa infestation can be determined with the following table:
| month | May June | July | August | September |
|---|---|---|---|---|
| For the time being safe | up to 5 mites (up to 1%) | up to 10 mites (up to 2%) | up to 15 mites (up to 3%) | |
| Treatment required in the near future | 5 to 25 mites (1 to 5%) | 10 to 25 mites (2 to 5%) | 15 to 25 mites (3 to 5%) | |
| Damage threshold exceeded, treat immediately | from 10 mites (from 2%) | from 25 mites (from 5%) | from 25 mites (from 5%) | from 25 mites (from 5%) |
The number of mites relates to 50 g of bee mass. "For the time being not at risk" means that summer treatment can be dispensed with if the check is repeated every four to six weeks in order to detect a reinvasion.
Weakness of the powdered sugar method
So that the powdered sugar method delivers accurate results and the bees do not die in the possibly moist powdered sugar, the method may only be used in absolutely dry weather with absolutely dry powdered sugar without lumps. The powdered sugar must be added immediately after sampling, because the bees will otherwise generate moisture in the shaker and the powdered sugar will become moist.
Weaknesses of other established methods
Other established methods for determining varroa infestation have the following disadvantages:
- With the litter diagnosis , the mite fall on the bottom of the beehive is determined. This method depends on the size of the colony and the breeding process. In addition, a bee and ant-proof 'diaper' is required, which must cover the entire floor, which is not easily possible in all hives. The result is only available after a few days.
- During the bee test , the bees are frozen for 24 hours and then the varroa mites are washed out with a commercially available washing-up liquid. This method is also dependent on the colony size and the breeding process. In addition, washing out is laborious and the bees have to be killed and the result is only available after 24 hours.
- A method similar to the bee sample, in which a defined number of bees are treated with alcohol and the mites are separated by shaking and through a sieve, gives direct results, but the bees are killed together with the mites.
Advantages of the powdered sugar method
The powdered sugar method enables a reliable infestation measurement directly at the apiary within a few minutes with little effort, in which no bees have to be killed.
Individual evidence
- ↑ Varroa infestation measurement with powdered sugar ( Memento from February 1, 2015 in the Internet Archive ) (PDF), Institute for Apiculture in Kirchhain, September 20, 2011
- ↑ Varroa control with the powdered sugar method. On: mellifera.ch from July 18, 2016
- ↑ Poker, V., Brunnemann, G., Büchler, R. (2011), bee test with powdered sugar. ADIZ 8/2011, pp. 7-9
Web links
- Varroa infestation measurement with powdered sugar at llh-hessen.de