Miticide treatments are an important component of varroa mite integrated pest management (IPM). During the summer of 2022, ATTTA conducted a Maritime-wide efficacy study of two miticides, Apivar® and ApiLife Var®. In this blog, we will share the results of this research and provide recommendations for varroa mite management.
Miticide Efficacy Testing Results
Integrated
pest management (IPM) is the best strategy for beekeepers to maintain healthy
colonies with low varroa mite populations. Part of IPM is regular, regional
efficacy testing of synthetic chemical treatments. Amitraz, in the form of Apivar®
strips, is the most heavily relied upon miticide by commercial beekeepers. There
is growing concern that mite populations are developing resistance to this
product, as was the case with the previous miticides, including tau-fluvalinate
(Apistan®), and flumethrin (Bayvarol). ApiLife Var® is the most recent miticide to be
registered for use in Canada and is yet little used by local beekeepers. It is
a volatile treatment with main active ingredient thymol. Our research sought to
test the efficacy of these two miticides in the Maritime region.
ATTTA collected samples of honey bees and associated mites
from 72 colonies across Nova Scotia, New Brunswick, and PEI. Based on these
samples, we found Apivar to have 89.15% efficacy. This is a satisfactory
representation of a mostly effective miticide treatment and comparable to the
results of previous efficacy testing in Canada (Rinkevich 2020; Morfin et al. 2022; Vandervalk, Nasr, and Dosdall
2014).
However, the reported effectiveness has decreased since the last trial by ATTTA
in 2017-2018, at which time Apivar was suggested to have 99.8% efficacy (Olmstead et al. 2019). This does not, in itself,
suggest changes of efficacy in our region.
The discrepancy in results is more likely due to methodological
difference. The previous ATTTA results
on Apivar efficacy are significantly higher than those indicated by our current
research and other work done by other Canadian research teams. Nonetheless, we conclude that beekeepers need
to be careful to preserve the efficacy of this product through proper IPM.
The results of the ApiLife Var efficacy testing suggest that it is an effective miticide, but that the standard, modified Pettis test used for contact miticide testing may not be appropriate for use with volatile treatments (Pettis et al 1998). There was an observable trend that ApiLife Var is more effective in killing mites than no treatment but not significantly so. The Pettis test was developed for miticides, such as Apivar, which spread through a colony through physical contact between bees. ApiLife Var, on the other hand, permeates a colony through evaporation. The low efficacy of the newly registered product found by this study suggests that a novel protocol for testing the efficacy of volatile compounds and essential oil miticides is required for accurate testing in a field-based methodology. This work was a first step in looking for an applied research tool for testing miticides with a different mode of action than contact miticides.
Overall, Apivar remains a useful treatment for varroa mite
control in the Maritime region. Results from ApiLife Var efficacy testing
suggest the product is effective, however the more striking result is that a
refined methodology for applied research is necessary for this type of product.
To maintain the efficacy of Apivar,
diligent IPM is necessary. For example, it is important to follow label
instruction exactly, including dosage and treatment timelines. This is also the
law! Rotating treatments is crucial, as well, and no single product should be exclusively
relied upon. Lastly, we recommend testing for varroa mites at least monthly and
always before and after treatments. Knowledge is power in varroa mite
control!
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