The Buzz Newsletter

Page 8

How Much Time Do You Have?

The following is an excerpt from a synopsis of a talk David Vander Dussen gave at the AHPA meeting in Houston, TX this past January. It was submitted originally by Lyle Johnston and printed in The Honey Producer newsletter.

Guest speaker at the field day, David Vander Dussen from Mite-Away II explained the importance of managing the Varroa population to keep colonies healthy.

With unselected stock, the varroa mites double every 22.4 days, approximately every three weeks. An otherwise health, strong colony can function with up to 3,000 varroa.

Since eradication of the varroa mites is impossible, when you treat what you are buying is time between treatments. The efficacy of the treatment determines how much time you have bought, as shown in the chart below.

At a 3,000 varroa treatment threshold, if a treatment has a 97% efficacy, you have bought 3.75 months between treatments. If a treatment has a 87% efficacy, you have bought 2.5 months between treatments.

Hard chemical treatments such as synthetic pyrethroids (e.g. fluvalinate) and organophosphates (e.g. coumaphos) are failing. The options are Mite-Away II single application formic acid pad (MAII), ApiLife Var, and now Apigaurd. Oxalic acid is being studied as well, as a possible treatment during broodless periods.

The formation and application method of MAII is what makes it effective (93.5%, +- 5%). Not all formic application methods are effective. The gel based formulation, now off the market, had a 70% efficacy (Mites of the Honey Bee, Dadant & Sons Inc 2001, page 190).
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FYI not included in the talk: Other products assessed by Stanghellini and Raybold for varroa treatment, fall 2003, in New Jersey. Published in the American Bee Journal, June 2004, Vol. 144. No.6

Single deep colonies:
Apistan: 95%, Sucroide: n/a, oxalic acid: 93%, ApiLife Var: 69%, and MiteGone: 66%.

Put these results on the chart and see how much time you are buying. Take home message: pay attention to the efficacy of the products you’re using. 1) Is what you are using working? And 2) are you buying the time you need to prevent major colony losses?
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Total cost for MAII for the year would be $8.37, and its’ single application formulation is easily worked into the beekeeping cycle. MAII works when there is brood in the hives. No residue issues. Resistance to formic acid is not expected. Considering how hard it has been to keep bees alive and get the almond pollination dollars MAII is the best return for the money.

Efficacy of Treatment Time Bought Chart
Starting varroa load: 3000 mites—working with unselected stock

% Efficacy	Tim Bought (weeks)	# Varroa Remaining
99.9	30	3
99.8	27	6
99.61	24	12
99.22	21	23
98.44	18	47
96.88	15	94
93.75	12	188
87.5	9	375
75	6	750
50	3	1500
0	0	3000
-3	-	6000	May be retrievable
-6	-	doomed	Major source of Varroa survivors.