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Date:         Fri, 29 Mar 1996 14:39:27 EDT
Sender:       Discussion of Bee Biology <BEE-L@CNSIBM.ALBANY.EDU>
From:         Medhat Nasr <MNASR@EVBHORT.UOGUELPH.CA>
Organization: Environ. Biology & Horticulture
Subject:      Re: Formic Acid

Aaron wrote:

I seem to recall that there were problems with formic acid prompting queen rejection and/or supercedure if used in uncontrolled or high concentration, which is why it was not a favourable means of varroa control.

Hi Aaron and beekeepers:

I have been doing research on Formic acid use to control tracheal mites for the last 3 years. Liu and Nasr (Amer. Bee J. , 132: 666- 668, 1992) found that three applications of 20 ml 65% formic acid / hive box at 5-7 days intervals are effective against tracheal mites. Use of 85% formic acid resulted in bees killing their queens. In Canada, Beekeepers used spray guns to deliver the recommended dose on absorbing paper towels or on the bottom board. Our beekeepers in Ontario had bad experience using spray guns. Because of the acid effects on the plastic material of the gun, the guns had mechanical breakdown during spray, spillage of the acid on the applicators' hands, and applying over dosages of formic acid. In addition, application of acid on the bottom board did give bees a chance to get out when it gets hot. Bees walked through the acid and burn their feet. We had one beekeepers lost 1-2 Lbs/hive from this type of application. These difficulties prompted us to develop a safe method to apply an effective dose of formic acid to bee colonies. We developed the Mite Wipe Pads which were easy to prepare, and delivered accurate effective doses to bee colonies. Overall, Mite Wipe reduced the beekeepers' risk of using formic acid in their hives. Also, we stayed away from applying the acid on the bottom board to avoid any catastrophic damage to the bees when it gets hot. These data are reported in the 94 Annual report to the Ontario Beekeepers' association " Tracheal mite resistance technology transfer by M. Nasr". The description given by Allen Dick is our research results which were conducted in Guelph, Ontario and published in Hive Lights.

Clark, 1994 (AM. Bee J.134: 829) and Szabo, 1994 (Am. Bee J. 134:837- 838) found that 6-7 applications of formic acid were effective against varroa mites.

formic acid safety: Formic acid is cytotoxic, corrosive, and can damage the skin and eyes on contact. Remember that bees are animals too. The issue of safe application should consider both the applicator and the bees. Use of high concentration can disturb the pheromone system in the hives and make bees leave the hives. From my observations, I found dehydrated eggs, dead young larvae, and dead queens when I used 85% formic acid.

My advice is: Always read and follow label instructions when using any product near your hives.

For the New Device, I would like to get a copy of the data which show the efficacy against mites and side effects on bees???


Medhat Nasr, Ph. D.

Ontario Beekeepers' Association 401-40 Vanier Dr. Guelph, Ontario. N1G 2X7

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