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Chemical resistance to varroa treatment.


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Hi all. I have a single brood box langstroth hive with plenty of bees and about a frame of brood. It has had varroa treatment (apistan strips x2 correctly positioned in the brood box) it's been in for five of the six weeks. There is evidence of deformed wing virus (12 bees) and looking harder with my reading glasses on, I could see varroa mites on some of the bees.

 

As an emergency measure I replaced the strips with fresh ones from my beebox for the final week of treatment but it looks like this may be grasping at straws.

 

Does anybody have experience of this situation and have any suggestions?

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Hi Neil,

 

You might find the deformed wings bees are from when the mite levels were high, its a virus that is spread by mites.

 

Checking bees with DWV isn't the best way to count the mite load, do a sugar shake count (detailed in the Green varroa book) or in this POST

 

Compare your levels to the charts and then go from there.

 

Thanks...Gary

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as above, i would not be using apistan or bayvarol without some form of testing to check it actually worked.

i would not expect to see mites on bees straight after using apistan.

only strip that will work is apivar, but its a bit slow and has a 10 week treatment time.

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Thanks Gary, I am guessing that the mite count will be above 1% at the end of the six week treatment period as I can see a lot of mites on the bees, but I will hope for the best. If it comes to the worst do you have a recommendation for a follow up treatment?

 

Thanks Tristan, the posts must have crossed at the same time. If the mite count is bad I will give the apivar a go.

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I think you are going down the right route now, so there is not much to say.

But I would NOT have changed the strips during middle of a treatment on any kind of treatment.

I also would not make decisions on what to do next after a sugar shake until two weeks after the strips come out.

If the mite count is above 2 when you test two weeks after the treatment, then I also would add apivar.

(2 mites in half a cup of bees).

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its basically at the end of the treatment at the moment, not half way through.

the catch is the longer you wait things get worse rapidly. at end of season a few extra weeks can mean a dead hive.

test now and get some idea on whats happening and make a decision quickly.

 

get a measuring cup and a sieve. check it tomorrow.

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I have just been reading that the relationship between apistan and DWV is complicated by the chemical weakening the bees resistance to the virus. The varroa count with one week to go is +1% just from a visual inspection so I will be anticipating a swap over from apistan to apivar at the end of the week. That said I will do a sugar shake then to get some hard numbers.

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its basically at the end of the treatment at the moment, not half way through.

the catch is the longer you wait things get worse rapidly. at end of season a few extra weeks can mean a dead hive.

test now and get some idea on whats happening and make a decision quickly.

 

get a measuring cup and a sieve. check it tomorrow.

 

Hi, it is a fine line between acting quickly and doing things in haste. We are still having new comb being drawn in our hives and it is all still 'happening'. I know it will be different here soon and different in other parts of the country, but I think it is best to remain calm and carry on following the instructions of the chosen treatment. It is late to be starting treatments, but it is better late than never. If things are done like changing strips, and putting in new strips before the current treatment has even finished, let alone had time to work and settle down again, before testing, they might as well not bother giving instructions out with the strips (?). Rather than making new decisions, I think it would be best to properly carry out the original decisions and do that job properly first.

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I think you are going down the right route now, so there is not much to say.

But I would NOT have changed the strips during middle of a treatment on any kind of treatment.

I also would not make decisions on what to do next after a sugar shake until two weeks after the strips come out.

If the mite count is above 2 when you test two weeks after the treatment, then I also would add apivar.

(2 mites in half a cup of bees).

If it isn't working, why wait?

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If it isn't working, why wait?

 

exactly how do you know it is not working? I've yet to see any information it is not working.

I think the Kiwimana post above is the correct advice with respect to mite count and DWV.

In regards to waiting two weeks after treatment before doing a sugar shake test, I hardly think that will suddenly kill the colony.

But I don't agree with changing strips part way through a treatment nor hasty decisions.

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Hi Chris, I agree that messing around with instructions is skating on thin ice, however this hive is one of three in the apiary and has visible mites and a degree of visible DWV, the other two are visibly mite and virus free (at the moment) the treatments went in at the same time.

So I have put an extra strip of the same treatment into the middle of the brood area, and this will come out with the other two at the end of the week. I will sugar shake all three in a week and re treat if necessary.

 

Our first hive a few years back was neglected and became overrun with varroa, the sight of hundreds of wingless bees dying on the ground is something I never want to see again.

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exactly how do you know it is not working? I've yet to see any information it is not working.

I think the Kiwimana post above is the correct advice with respect to mite count and DWV.

In regards to waiting two weeks after treatment before doing a sugar shake test, I hardly think that will suddenly kill the colony.

But I don't agree with changing strips part way through a treatment nor hasty decisions.

Sorry dude I completely disagree with you on that one. That far into the treatment period if it was going to work it would have. The only things I would have done differently is used the opposite class of chemical and I would have done a resistance test. Just because you make a decision quickly doesn't mean it's bad. And, at this time of year that 2 weeks could make the difference. The health of the hive takes a few generations of workers to fully recover....

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Hi, it is a fine line between acting quickly and doing things in haste. We are still having new comb being drawn in our hives and it is all still 'happening'. I know it will be different here soon and different in other parts of the country, but I think it is best to remain calm and carry on following the instructions of the chosen treatment. It is late to be starting treatments, but it is better late than never. If things are done like changing strips, and putting in new strips before the current treatment has even finished, let alone had time to work and settle down again, before testing, they might as well not bother giving instructions out with the strips (?). Rather than making new decisions, I think it would be best to properly carry out the original decisions and do that job properly first.

if you are late it might as well be never, cause its going to be dead either way.

 

the simple problem is there is little to no time left to retreat. so waiting is simply not an option you have. mites numbers are at their peak and bee population is dwindling.

while seeing mites is not accurate it fairly safe to assume that after treating you really shouldn't be seeing mites on bees, especially as apistan/bayvarol have a fast kill rate, by mem something like 95-98% within 48hrs. so after 4 weeks and with such little brood, you should not be seeing mites on bees.

fairly safe to assume a high rate of resistance.

 

as always with apistan/bayvarol you should always be checking that it does actually work.

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On a side note, once a packet of apivar has been opened is it possible to reseal packet with remaining unused strips?

 

If there is still mites on the bees, perhaps using mite away quick strips or formic/oxalic acid to knock down the mites rapidly, its quite late in the year to be treating them as they cant be too far from hibernating

 

Correct me if im wrong but apistan/bayvarol potency in the hive diminishes over the treatment period whilst apivar increases

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On a side note, once a packet of apivar has been opened is it possible to reseal packet with remaining unused strips?

not really.

they are vacuum packed and once opened the chem starts to be released from the strip.

 

 

If there is still mites on the bees, perhaps using mite away quick strips or formic/oxalic acid to knock down the mites rapidly

possibly. trouble is it damages bees. to much damage on a hive thats going down hill could kill it. other than that a quick knock down would help a lot.

 

Correct me if im wrong but apistan/bayvarol potency in the hive diminishes over the treatment period whilst apivar increases

depends on what you call "potency".

i would expect apivar to do the same.

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possibly. trouble is it damages bees. to much damage on a hive thats going down hill could kill it. other than that a quick knock down would help a lot.

 

Damned if you do and damned if you don't

 

Would it be possible combine this hive with another and add apivar strips?

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