Apivar 2.0 Adverse Effects
October 18, 2026
This summer the internet lit up with beekeepers reporting excessive worker bee mortality, or even the absconding of colonies, during treatment with the new Apivar 2.0 strips. These reports blindsided the French pharmaceutical company, Véto-pharma, which produces the product.
INTRODUCTION
Commercial beekeepers worldwide have long used amitraz to control varroa, at first applying products labeled for cattle on sticks, towels, or by burning, and as products were eventually brought to market registered for use in beehives (such as Apivar strips in the U.S.) many beekeepers shifted to the more expensive “legal” treatments.
In response to beekeeper complaints that Apivar “took to long” to reduce mite counts, Véto-pharma developed faster-acting Amiflex and Amiflex 2.0 gel. And this year Véto brought faster acting Apivar 2.0 strips to market.
AN UNFORSEEN ISSUE
Most beekeepers who have used Apivar 2.0 are happy with the product, but to everyone’s surprise, some have reported that it appeared to have caused serious adverse effects to their colonies. Véto-pharma was blindsided by these reports, and has released an update for U.S. beekeepers at https://www.veto-pharma.com/beekeeping-products/apivar-2-0-update-for-us-beekeeepers/, and are trying to nail down the cause.
did Véto do their homework?
Beekeepers have asked me how the heck Véto could have brought a product to market without knowing this could happen? The company’s been producing reliable amitraz products for many years. Had they performed due diligence in their testing of this new formulation?
I asked their new U.S. sales manager, Fabiana Ahumada, whether Véto would be willing to show me their testing data. She forwarded my request to Rémi Padé (Véto’s Bee R&D Technical and Innovation Manager), who went out of his way to answer my probing questions, and shared Véto’s testing data with me for review.
Disclaimer
I have not used the product, nor do I have any financial association with Véto-pharma. My only reason for doing this is to answer questions that I’ve received from beekeepers.
My evaluation of the data
Before release, Apivar 2.0 went through a multi-year development program, including controlled tolerance and efficacy studies, as well as subsequent informal beekeeper experience trials across different geographies and hive types. The company looked for adverse effects in formal testing in some 168 hives in 15 different apiaries in the E.U., New Zealand, and the U.S., as well as much broader informal field testing in commercial apiaries.
In their formal trials, they followed the European Guideline on Veterinary Medicinal Products Controlling Varroa destructor Parasitosis in Bees [[1]], and used dead bee traps in front of the hives to count any dead bees or pupae before and during the exposure period. At each assessment (e.g., at Days 0, 1, 4, 7, 10, 14, 21, 28, and 35) during treatment, they also observed the behavior of bees at the hive entrance, and any unexpected event was recorded: queen loss, high bee or larvae mortality, high activity of bees, aggressiveness, unintended variation of the colony structure, etc.
Rémi shared a number of graphs of the number of dead bees found in the traps during the treatment period – I didn’t see any evidence of Apivar 2.0 causing issues.
I of course asked whether they had tested Apivar 2.0 during hot weather or high humidity. They had. In a 2025 test at Auburn University in Georgia, daytime highs reached 91°F (90% RH) without any signs of adverse effects. And their data set from tests in Spain this summer show that Apivar 2.0 had been applied at temperatures above 105°F (and relative humidities up to 78%), again without problems.
Conclusion
My evaluation of Véto’s data indicates that the company did indeed perform due diligence in their testing, and was totally caught by surprise by the reports of adverse effects from the product (especially since such effects were only reported by a minority of the users).
It may take a while for Véto to figure it out. There’s the question as to the before-treatment mite infestation rates and general health of the colonies that exhibited apparent adverse effects, and other factors that may have been involved.
I did bring to their attention that one U.S. commercial beekeeper felt that there was a strong correlation between worker mortality and the presence of oxalic strip remnants in the hive during treatment with Apivar 2.0.
I did ask Fabiana whether Véto was offering any sort of compensation to beekeepers who suffered serious losses associated with Apivar 2.0. Her reasonable answer was “At this stage, we are still in the investigation process to fully understand the different factors that may have contributed, including environmental and application conditions. We want to make sure that all available information is properly evaluated before drawing any conclusions. Our focus right now is understanding what occurred and identifying any factors that may have contributed.”
In the interim, I suggest that adversely affected beekeepers can help Véto get to the root of the problem by submitting detailed written reports (temperature, humidity, colony conditions, pre-treatment mite levels, other miticides present, etc) of their suspected observations of adverse effects to the company at pv@vetopharma.com
[1]https://www.ema.europa.eu/en/documents/scientific-guideline/draft-guideline-veterinary-medicinal-products-controlling-varroa-destructor-parasitosis-bees-revision-2_en.pdf
