Tag Archives: Apivar

Apivar & Apitraz = Amitraz

The range of miticides available ‘off the shelf‘ to UK beekeepers has recently been increased by the introduction of Apitraz and Apivar.

‘Off the shelf’ because, until recently, these were only available with a veterinary prescription.

Considering the extensive coverage on this site of oxalic acid-containing miticides and more recent posts about the – regularly ineffective – Apistan, it seemed fair and appropriate to write something on the active ingredient and mode of action of these new products.

Mites on drone pupae ...

Mites on drone pupae …

Conveniently, because the active ingredient is identical, these can be dealt with together in a single post. The similarities don’t end there. The amount of the active ingredient is the same and the way it is administered is very similar. They are different commercial products; Apitraz is distributed by Laboratorios Calier, SA and sold by BS Honeybees, Amitraz is distributed by Veto Pharma and sold by Thorne’s. The strips have a different appearance and a slightly different mechanism by which they are hung in the hive.

They even cost about the same – a single packet of 10 strips (sufficient to treat 5 hives) costs £30.50 and £31 respectively for Apitraz and Apivar.

Amitraz

The active ingredient in both Apitraz and Apivar is Amitraz.

Yes … I find these three names confusing similar as well 😉

Amitraz is a synthetic acaricide – a pesticide that kills mites and ticks. It was discovered and developed almost 50 years ago by the Boots Co. (the drug development predecessor of the Boots the Chemist 1 found in most high streets). Amitraz is the active ingredient in a range of medicines approved by the Veterinary Medicine Directorate, including Aludex and Certifect, both of which are used to treat mange in dogs.

Amitraz

Amitraz …

For completeness I should add that Amitraz used to be used by US beekeepers and was sold as a generic pesticide under the name Taktic, though this was withdrawn in about 2014. I believe that Apivar is now available as a slow-release Amitraz-containing Varroa treatment in the US.

Mechanism of action

Amitraz has to be metabolised (essentially ‘modified’) before it is active. This modification occurs much less well in bees than in mites. In fact, the toxicity of Amitraz for bees has been determined to be about 7000 times less than in mites.

Once converted into an ‘active’ form the most important mechanism of action for Amitraz is through interaction with the alpha-adrenoreceptor and octopamine receptors of Varroa 2.

OK, since you asked … octopamine receptors normally bind a neurotransmitter called – rather unimaginatively – octopamine. Quelle surprise as an apiculteur would say. It’s likely that occupancy of these receptors by Amitraz triggers a series of so-called downstream events that change the behaviour of Varroa. Similarly, amitraz also acts as an agonist 3 when binding to the alpha-adrenoreceptor which normally interacts with catecholamines. This results in neurotoxicity and preconvulsant effects.

That all sounds a bit vague. Essentially, amitraz binds and activates receptors that are critically important in a range of important aspects of the Varroa activity and behaviour. Remember here that the mite is entirely dependent upon proper interaction with the bee to complete the life cycle. For example, if the mite fails to enter a cell at the correct time or doesn’t hitch a ride on a passing nurse bee for a few days, it will likely perish.

Amitraz changes behaviour and so exhibits miticidal activity. It has additional activities as well … these multiple routes of action may explain why resistance to amitraz is slow to develop. More on this later.

Usage of Apitraz and Apivar

Both Apitraz and Apivar are formulated as plastic strips impregnated with amitraz. The bees must come into contact with the strips to transmit the amitraz around the hive. Two strips are therefore placed between frames approximately one-third of the way in from each side of the brood box – typically between frames 4 & 5 and 7 & 8 of an 11 frame box. This assumes the bees occupy the entire box. If they don’t, arrange the strips in the appropriate part of the box with 2 frames separating them. Both types of amitraz-containing strips have a means of securing them hanging between the frames.

The recommended treatment period is 6 (Apitraz, or Apivar with little/brood present) to 10 weeks (Apivar with brood present). As with Apistan, treatment should not be applied during a honey flow or when honey supers are present. Further details are included on the comprehensive instructions provided with both products. There’s also a reasonable amount of information on this New Zealand website for Apivar.

Efficacy

This is the good bit … very, very effective. When used properly, amitraz-containing miticides can kill up to 99% of the Varroa in a colony.

Toxicity and wax residues

The good news first. Amitraz does not accumulate in wax to any significant extent. It is not wax-soluble. This is in contrast to Apistan which is found as a contaminant in most commercially-available beeswax foundation.

And now the bad news. Beekeepers also have alpha-adrenoreceptors and octopamine receptors. So do dogs and fish and bees. Although amitraz has increased specificity for the receptors in mites and ticks, it can also interact with the receptors in other organisms. Consequently, amitraz can be toxic. In fact, if you ingest enough it can be very toxic. Symptoms of amitraz intoxication include CNS depression, respiratory failure, miosis, hypothermia, hyperglycemia, loss of consciousness, vomiting and bradycardia.

And it can kill you.

Admittedly, the doses required to achieve this are large, but it’s worth being aware of what you’re dealing with. Amitraz-containing strips should be used only as described in the instructions for use, handled with gloves and discarded responsibly after use.

Resistance

Multiple modes of action makes it much more difficult for resistance to evolve. But it can and does. Resistance to amitraz is well-documented and is understood at the molecular level. However, this is in cattle ticks, not Varroa.

At least, not yet, though there are numerous anecdotal reports of Varroa resistance.

I’ll deal with resistance in a separate post. It’s an important subject and avoiding it is a priority if amitraz-containing compounds are going to remain effective for Varroa control.

Cost

At about £6 per colony, amitraz-containing treatments are not significantly more expensive than the majority of other approved miticides, perhaps with the exception of Api-Bioxal which is appreciably less expensive (though more restricted in the ways it can effectively be administered 4).

Apivar ...

Apivar …

When you purchase a couple of packets of Apivar – enough for 10 colonies – it might feel expensive 5. However, it’s worth remembering that this is still less than the likely ‘profit’ on a couple of jars of your fabulous local honey per colony per year, which seems pretty reasonable in the overall scheme of things.

And, if you look after your colonies well, you are maximising the potential yield of honey in the future … so you’ll be able to afford it 😉


 

Those pesky mites

DWV symptoms

DWV symptoms

If you haven’t yet treated your colonies to reduce Varroa levels before the winter arrives it may well be too late. High Varroa levels are known to result in the transmission of virulent strains of deformed wing virus (DWV). These replicate to very high levels and reduce the lifespan of bees. If this happens to the ‘winter bees’ raised in late summer/early autumn there’s a significant chance that the colony will die during the winter.

Mite levels in most of my colonies have been very low this year. Partly due to thorough Varroa management in the 2015/16 winter (the only thing I can take credit for), partly due to the relative sparsity of beekeepers in Fife, partly due to the late Spring and consequent slow build-up of colonies and partly due to an extended mid-season brood break when requeening. Most colonies yielded only a small number of mites (<50) during and after a 3 x 5 day treatment regime (to be discussed in detail in a later post) by sublimation.

Infested arrivals

The low mite drop definitely wasn’t due to operator error or vaporiser malfunction. At the same time I treated a swarm that had moved into a bait hive in early June …

Out, damn'd mite ...

Out, damn’d mite …

This is ~20% of the Varroa tray. Have a guess at the number of mites in this view only. Click on the image to read the full legend which includes the mite count.

The image above was taken on the 18th of September, a day or two after starting the second round of 3 x 5 day treatments. The colony really was riddled. When a colony swarms 35% of the mites in the colony leave with the swarm (or, in this case, arrives with it). For this reason the swarm was treated for mites shortly after it arrived in June. It did have a reasonably high mite load but subsequently built up very quickly and didn’t experience the mid-season brood break my other colonies benefitted from.

The colony now has an acceptable mite drop (<1 per day). Similar colonies are still rearing brood – I’ve not checked this one, but they are bringing in some pollen from somewhere – so there’s a possibility the majority of the remaining mites are tucked away in sealed cells. I’ll keep a close eye on this colony through the next few weeks and will be treating again midwinter to further reduce the parasite burden.

Treat ’em right

If you are treating this late in the season make sure you use a miticide that is appropriate for the conditions. Apiguard (a thymol-containing treatment) is almost certainly unsuitable unless you’re living in southern France as it needs a temperature of 15°C to be effective. MAQS has a recommended temperature minimum of 10°C which may be achievable.

Hard chemicals such as Apivar and Apistan can be used at lower temperatures but there’s little point in treating with Apistan unless you’re certain all your mites are sensitive. They almost certainly are not as Apistan/Bayvarol resistance is very widespread in the UK mite population. Just because you get an increased mite drop in the presence of Apistan does not mean treatment has been effective. Perhaps all you’ve done is killed the sensitive mites in the population, leaving the remainder untroubled. This is what’s known as a bad idea … both for your bees next season and for your neighbours.


 I’m posting this now due to the large number of searches for, and visits to, pages on use of Apiguard or other Varroa treatments. These are currently running second to ‘fondant‘ in one form or another.