2012 Annual Report
1a.Objectives (from AD-416):
The objectives of this cooperative research project is: a) to determine the efficacy of an innovative formulation of formic acid preparation for controlling Varroa destructor under field conditions, b) to determine its impact, if any, on colony strength, and c) to measure residues in honey.
1b.Approach (from AD-416):
1. The test will be conducted near Weslaco, TX, using USDA-owned colonies.
2. Colonies meeting our criteria for size and health will be selected. These will be treated with: a) nothing, b) NOD product applied to non-supered colonies, or c) NOD product applied to supered colonies.
3. Impact on colonies will be assessed by scoring adult bee strength before and after treatment. During the first 16 days of treatment dead adult workers will be collected from Todd dead bee traps and counted.
4. Efficacy will be assessed by a. counting all mites dropping from colonies during treatment, and b. challenging remaining living mites by applying two known control agents after treatment.
The NOD Apiary Products flash formic acid strip (FFAS) half dose was tested for efficacy against the parasitic mite Varroa destructor. The half dose strip was tested with or without honey supers above a double brood chamber colony. The treatment was applied to infested honey bee colonies, located near San Manuel, Texas, for three days and removed. Varroa mite drop was monitored throughout the 16-day observation period (9-25 August 2010), to determine efficacy. The treatment groups were (n = 10), a) negative control, b) FFAS with honey supers (FFAS+HS), and c) FFAS without honey supers (FFAS-HS).
Mite mortality was recorded during the 16-day observation period by means of sticky boards, which were replaced every 3, 4, or 5 days. Average remaining mite populations (those falling during a 8-day challenge with amitraz and Apiguard post treatment) were: negative control, 1789.8 mites; FFAS+HS, 1171.0 mites; FFAS-HS, 1152.2 mites. Both treatments were not significantly different than the negative control.
As a rule of thumb, we consider control to be adequate if there is a 10-fold difference, between the negative control and the experimental treatment groups. Using this guideline, the half dose strip did not provide good efficacy. In a separate phase of the study, utilizing the same colonies, we monitored the number of dead adult bees with Todd dead bee traps, during the 16-day observation period. Adult worker honey bee mortality were: negative control, 67.8 adults; FFAS+HS, 48.6 adults; and FFAS-HS, 54.6 adults. Average mortality in both treatment groups was not significantly higher than the negative control group. The efficacy of the half dose FFAS strips was not good; however, adverse impact on honey bee colonies was not observed with these half dose strips.
We conducted an additional trial during February 2011 near Bakersfield, California. We stopped the trial after only a few days when we saw that the product was having a negative impact on a cooperator's honey bee colonies. The cooperator was notified of this.