Varroa Control Tips – Simple Messages, with Huge Potential Payoffs

  ADVERTORIAL: NZ BEESWAX

By Nick Taylor – NZ Beeswax general manager

Nick Taylor

These words don’t come easy… after three weeks of attending Australian State beekeeping conferences, I am in admiration of the maturity and leadership demonstrated by a group of influential commercial Australian beekeepers on the management of varroa.

“I thought I could just use treatment ‘x’ only,” some said, “I thought I had time” cried another, “they looked ok, so I just kept going”. They all got smashed. More importantly, they put their hand up and said “it’s on me” and are now sharing their experiences for others to learn.

The mistakes and lessons are as old as Varroa destructor (it’s in the name people) itself. Australia has dialed up the varroa intensity through climate, feral (both in the colonies and beekeeper category) density, near 12-month brood raising, and migratory business models, and they are learning fast because of it.

Many of those lessons are just as pertinent here, and serve as a good reminder for Kiwis and Aussies alike. The most pertinent include:

• Knock them down and keep them down! - Bring out the ‘tier 1’ (aka ‘big guns’) treatments in the spring and autumn. That’s the proven and trusted strips like Apivar, Bayvarol and Formic Pro. Leave the 3rd tier remedies for suppression.

• Timing is critical - A few weeks can make all the difference. One very large NSW beekeeper shared his experience of pushing his luck and waiting until autumn mite counts in washes got above thresholds before treating. By the time they got to putting strips in (5-6 weeks later) “the counts were off the charts, and those last truck loads paid the toll”.

• Pros and cons - There are a wide range of varroa treatment options and all candidly come with their own unique advantages and disadvantages. Some being: low treatment cost but high labour/travel cost, pain to install and remove, hard on both the mites and the bees, variability in efficacy, temperature constraints, hard on bee gut health and beekeeper health etc. Others come with upfront costs to the beekeeper, but more consistent and improved efficacy, while giving an 8-10 week halo over the hives. There’s no free lunches, and no silver bullets (despite the greasy salesman’s claims) and the best you can do is mix and match to create your own 12 month strategy.

• The most expensive treatment is a dead hive: Dead and weak hives don’t produce honey, and pollinators won’t pay for empty boxes.

‘1st Tier’ varroa treatments such as Apivar are beekeepers’ best bet to ‘reset the clock’ in spring, before looking to ‘3rd Tier’ options later in spring and summer to continue suppression.

Timely Spring Reminders

The rapid colony growth in spring hides a multitude of sins but, remember, decisions now have a ripple on effect into the summer crop performance and ultimately the looming autumn cliff (where the exponential wave of mites overwhelms the tapering population of adult bees).

Best practice – focus on what you can control, starting with hitting mites with a core ‘1st tier’ treatment in spring at full dose, for the full treatment period, with an alternate chemical class from what you used in the autumn. With the clock reset (that is, mite counts low and having practiced an integrated pest management approach), you can then add 3rd tier suppression tool(s) during the late-spring/summer.

As always, there is the calculated gamble of only using 3rd tier soft/flash treatments, underdosing, not alternating, spot treating only, skipping or delaying a round because they ‘looked good’ etc. But you do these at your peril, as the Aussies have fast learned.

One More Tip – Stay in Contact

Want a simple tip, which is proven by research, and won’t cost you a single extra cent…

The leading strip treatments work by contact only. The more bees that get in contact with the strips, the more active ingredient they will collect from the surface. That is why the strips always need to be placed in the centre of the brood, as this is where we can observe the highest activity in the hive, resulting in the highest number of potential contacts. It’s also here that varroa mites will emerge from the brood cells.

Bonus tip, Apivar can optionally be hung between the frames with a toothpick/skewer/nail, exposing both sides of the strip to the movement of bees, maximising contact.

During a long-action treatment (e.g. 6-10 weeks for Apivar and 6-8 weeks for Bayvarol) it is not rare to see the strips covered by wax and propolis after several weeks. However, the propolis/wax will decrease the accessible surface on the strips for bees and therefore reduce the number of potential contacts. Moreover, after a few weeks, the bees’ cluster may have moved within the brood box. Thus, during your site visits, we advise scraping the strips systematically at mid-treatment (with a hive-tool) and repositioning them in the centre of the bee cluster.

Don’t just take my word for it… in France, a study (by ADAPI, the French Association for the Development of Beekeeping) found this simple habit of cleaning and repositioning strips resulted in a 1 to 4% improvement in treatment efficacy. Any varroa mite modelling will tell you, the hive health and honey production gains resulting from a 99% vs 95% efficacy result is well worth achieving.

Varroa control – we’ve had 20 years now to learn that the lost production resulting from cutting corners in your treatment regime is nowhere near worth it, and it’s something the Aussies are learning real quick.