Last week's blog talked about synthetic acaricides as part of an IPM approach to managing Varroa mites. In order to prevent resistance and maintain efficacy, additional methods must be employed and many beekeepers are looking to non-synthetic compounds as alternatives. Some of these options are discussed below.
More about those tiny, hive invading shrews this week! Read on to find out about CSI "Operation Shrew"!
Soft Chemical Treatment Options for Varroa Control
In our regions, oxalic acid is often used as an autumn treatment
for Varroa mites. This is done as a
stand alone or a late season supplement to some other earlier treatment. The vapour, or sublimation, application seems
to work well in our region as it is less dependent on ambient temperature and
humidity. Oxalic acid vapour is also
most effective on a colony with no brood and another reason for using it later
in the beekeeping year. A team of
researchers from the University of Guelph has just published a report on a
range of soft chemicals to treat Varroa mites which includes some new ideas for
the use of oxalic acid. One of the
limitations of vaporized varroacides is the delivery mechanism and possible improvements
need to be explored, as has been done by this research team. This week we will look at this research and
some other options available to beekeepers.
Substances like organic acids and essential oils to treat
Varroa mites are currently of importance, and poised to become more so, to
beekeepers rotating acaricides as part of a IPM program.
The environmental persistence of these chemicals is less, therefore they
are viewed as more natural but this does not mean that they are necessarily less potent
acaricides. The essential oil, thymol,
derived from the herb thyme is an excellent example. Work done by ATTTA in 2017 reported that Thymovar®
(active ingredient: thymol) was an effective treatment for Varroa mites in our region. Recent work by a research team led by Dr. Ernesto Guzman-Novoa
out of the University of Guelph, reported that other methods of application for
thymol were also effective. This group
has reported that thymol, as either a wet or dry (dust) treatment, achieved up to 96.6%
efficacy. The most effective application method was thymol dust. These workers also reported that
oxalic acid and oregano essential oil were effective but less than thymol as
applied in this trial (the efficacy range for all three treatments across two types
of application was 21 – 96%). It must be
noted that this work did not include oxalic acid vapour as one of the experimental delivery
methods. This is interesting and
necessary work as often times new, sometimes dubious treatments, may be introduced to market with unproven
efficacy. It is necessary to prove new treatments and applications!
The success of essential oil and organic acid treatments is
highly dependent on the type of application and the ambient conditions. This would indicate that these methods of Varroa
mite control need more knowledge and expertise than do synthetic
acaricides. These soft chemical treatments
are favored by some beekeepers due to them leaving no residues and therefore may
have a reduced environmental impact. This brief overview by no means provides the full picture when it comes to soft chemical Varroa controls, so you are encouraged to find out more...
Opportunity for Atlantic Canadian Beekeepers to take part in shrew research!
Do you have shrews in your apiaries? A research team, led by Professor Don Stewart, based at Acadia University, Wolfville, NS is collecting data from beekeepers who place specially designed devices in their bee yards. These devices will allow for the identification, through DNA analysis, of shrew species using the collected scat.
A system to track shrews using feeding tubes has been used in Great Britain for many years. The feeding tubes consist of short lengths of plastic tube containing insect larvae as shrew food. These tubes do not catch or hold the shrews. The shrews enter to feed, and because of their high metabolic activity, immediately deposit scats. This system was developed by Dr. Sara Churchfield in the UK to identify rare water shrews in that country. The UK team could use size, shape and contents to identify the type of shrew because they only have three species each with quite distinct feces. In contrast, this project uses “DNA Barcoding” to identify which of our seven species of shrew has deposited the feces in the trap (see image below). Feeding tubes can be placed in various habitats, or around bee hives, and feces collected and sent to Acadia for analysis. If the quality of the sample is sufficient, the beekeepers will then be informed which species of shrew was identified in their bee yards!
Contact ATTTA for details of how to receive a shrew feeding tube to place in, or around, your apiaries and participate in this research project. Use the email contact below!
Connecting with ATTTA Specialists
If you’d like to connect with ATTTA specialists or learn more about our program, you can:
visit our website at https://www.perennia.ca/portfolio-items/honey-bees/
Email abyers@perennia.ca
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