A Field Test of Apitablets
Feeding Thymol for Varroa Control 1
Consumption/Removal of the Tablets. 11
Confirmation of Consumption. 12
A Field Test of Apitablets
Randy Oliver
ScientificBeekeeping.com
First published in ABJ April 2025
I’m often asked by developers of new items for beekeepers, to give their products a test. So when Mehmet Batir asked me to test his new Apitablets, since they seemed promising, I gave them a try.
Feeding Thymol for Varroa Control
I’ve got lots of experience with using thymol as a fumigant to control varroa, but have not tried application in sugar patties fed to the bees, an idea suggested by Dr. Diana Sammataro [[1]]. Since then there have been some studies on the sublethal effects of fed thymol upon honey bees or their larvae [[2]], indicating that so long as the thymol percentage was kept below 0.5%, it would be safe for the bees [[3]]. And finally, there was a study by Cengiz [[4]] that demonstrated the fed thymol in sugar cake could be efficacious against varroa.
Practical application: A thymol-infused sugar block that could be fed to bees could be a great addition to our arsenal against varroa. But since I’ve repeatedly observed that bees don’t like the smell of thymol and go to great lengths to remove it from the hive, my question would be whether they would actually consume the treatment.
During our hot California Augusts and late-summer dearth, I often treat colonies with thymol for varroa control, and protein for buildup. So when Mehmet asked me to try his honey bee health product, Apitablets (Figure 1), I was curious to try the combination — solely for general colony health benefit (since the product is not labeled for miticidal purposes). That said, I was concerned about the health of my beloved varroa mites due to the thymol in the tablets, so also monitored their strength.
Fig. 1 Apitablets don’t list the ingredients in order of weight. They are not registered as a pesticide, so the warning to wear protective gloves is only a suggestion. The manufacturer’s website [[5]] prescribes placing one tablet on top of the frames in each brood box twice in the fall, 30 days apart.
Setup
I wanted to start with two equalized groups (Test and Control) of 12 hives each, so in late June (during our nectar flow) we stocked a semi-isolated yard with ~30 nucs with new queens, and allowed the colonies to grow, swapping combs of bees for three weeks to equalize them (Figure 2), and feeding sugar syrup to promote colony buildup.
Fig. 2 We equalized the Test and Control groups for both starting strength and varroa infestation rate.
20 July: Performed mite washes. Moved out two high-mite hives (since I didn’t want to lose colonies to excessive varroa loads), and moved in some low-mite hives. Added second deep brood chambers of drawn comb and combs of brood and bees with matching mite wash counts to equalize and locate brood in the centers of both brood chambers (Figure 3).
Fig. 3 The test yard, towards the end of the trial. Note the lack of forage.
22 July: Pollen and nectar flow ended, so a good time to start a test of a product claiming to promote colony health. Randomly assigned treatments, blocked by starting mite count. Graded each colony for starting strength and confirmed that the mean starting strength was approximately equal for each group. Applied 1 Apitablet to the Test hives (Figure 4), and fed 1 lb. pollen sub and half gallon 1:1 syrup to all hives.
Fig. 4 We placed each tablet in the center of the cluster (you should wear gloves).
31 July: Negligible pollen or nectar flow. Pollen sub mostly consumed. Fed another 1 lb. pollen patty and ½ gal syrup. Tablets roughly half chewed away. No apparent brood disruption by the tablets.
19 August: Inspected hives (Figures 5 & 6).
Fig. 5 The bees clearly did not like the odor of the tablets (presumably due to their thymol content), moving their broodnests away from them (a typical response to thymol). In this photo you can see the tablet stuck to the top bar of the comb that had been in the center, with the combs that had been to either side behind it. The brood area in all three combs had been shifted away from the tablet.
Fig. 6 We observed the same in most Test hives. Here are views of both sides of the central comb with its tablet stuck to the top. Due to the obvious repellency to the thymol, I fully expected that the tablets would suppress varroa reproduction.
6 Sept: The Apitablets had been mostly removed by the bees, ranging from only a trace left to nearly untouched (Figure 7). We replaced them all with a second fresh tablet. We again graded for strength, took mite counts, and fed syrup and pollen sub.
Fig. 7 Most Test colonies to consumed/removed most or all of the first two tablets applied (data in Fig. 10).
30 Sept: Apitablets averaged being half removed, so we again replaced them with fresh ones (this was a third application). Took mite counts, graded for strength, and fed syrup and pollen sub.
27 Oct: Took ending mite wash counts and graded for final strength (Figure 8). Most of the Apitablets applied a month ago were largely still intact.
Fig. 8 We followed the manufacturer’s recommendations to apply Apitablets during hot summer weather (“During the sweltering months…Apitablet’s inclusion of essential oils not only aids in fortifying bee immunity but also assists in temperature regulation within the hive”), and then through the fall (“Applying Apitablet twice during the fall, with a 30-day interval, sets the stage for strong overwintering colonies”).
Results
Since Apitablets make no pesticidal claims, what we were testing was whether they improved colony health. We measured cluster size as a proxy for colony health (Figure 9).
Fig. 9 On average, the higher red columns indicate that the surviving Control colonies gained strength, whereas the Apitablet hives lost strength (pairs lacking a red column indicate that the colony died); however, the changes were not significantly different.
Again, Apitablets make no claim for pesticidal use, but out of curiosity, we did take mite wash counts (Figure 10).
Fig. 10 Although Apitablets make no miticidal claims, the changes in mite counts were not significantly different between the two groups.
As far as the effect of applying three Apitablets, let’s compare the average cluster size progressions of the two groups (excluding colonies that went queenless, but including those that died from varroa as zeroes). The Control group went from 8.0 to 6.4 frames of bees (FOB); the Apitablet group from 8.8 to 6.8 FOB. So there was no apparent benefit as far as maintaining colony strength. Since many of the hives still contained brood at final grading, I inspected each colony’s broodnest. Reviewing my notes, there was no noticeable difference between the Test and Control groups.
To my great surprise, the application of three Apitablets (continually releasing thymol over 97 days) also did not appear to affect my beloved varroa mites. I’ve plotted the progression of their infestation rates over time in Figure 11.
Fig. 11 My concern for my pet varroa mites was unfounded, since the tablets did not exhibit any appreciable effect upon growth of their populations. The odd thing about the growth curves is the notable rise in the mite levels in the Test group in September, followed by a reduction in the survivors in October, when some of Control counts went up.
Practical note: Since we’re having success at breeding for mite resistance, it’s more difficult for us to set up trials involving mite control, since as you can see in the Control group, a proportion of our colonies keep mites largely under control by themselves.
Discussion
Beekeepers worldwide are offered all sorts of products claiming to do this or that to improve colony health. It’s easy to make claims, but what we beekeepers reasonably would like to see is some hard data to support those claims.
The claims for Apitablets are that they “support honey bee health and vitality” and “promote colony strength and well-being.” In this trial I tested whether they promoted colony strength, but had every reason to expect that the thymol in them would also affect varroa.
One of the first things we noticed about the tablets (which are nearly the size of a hockey puck) is that they were too thick, and jacked up the frames above them in the upper brood chamber (Figure 12).
Fig. 12 Note how the Apitablet pushed the two frames above it clear up to the hive cover.
It’s not clear whether the bees removed the Tablets as irritants, or gobbled them as food. I wish that I could say otherwise, but we disappointingly saw no benefit to colony performance from applying them continuously from late July through late October. And although they contained thymol, to my great surprise they did not appear to suppress the growth of varroa, since there were substantial increases in the mite populations in half the Test colonies.
I spoke with Mehmet about our results, to see whether he had any comments. He wondered whether we had under dosed, since he recommends one tablet per box ten combs of bees. Since even our very largest colonies barely made that strength, under dosing was clearly not an issue (not to mention that we applied three continuous doses).
Consumption/Removal of the Tablets
There was no lack of consumption/removal of the first two rounds of the tablets by the bees, with many of the Test colonies completely consuming/removing the first two tablets given.
Practical note: The efficacy of Apiguard thymol gel is dependent upon the bees transporting the gel particles down through the broodnest, with no ingestion involved [[6]]. So it’s not clear that actual consumption is necessary.
Since we had recorded the amounts of tablets remaining as we replaced them, I checked to see whether there was a correlation between the amount of Apitablet consumed/removed vs the buildup of mites (Figure 13).
Fig. 13 Athough there was an extremely weak negative correlation between tablet removal and mite buildup, considerable mite increases occurred in some colonies that had fully consumed/removed 1-2 full tablets.
Confirmation of Consumption
When I asked, Mehmet assumed that the mode of action of the Apitablets was due to ingestion, rather than physical removal. He wondered whether our feeding of pollen sub and syrup had kept the bees from consuming the tablets (although his website says that it’s fine to apply the tablets during a pollen and nectar flow). But there apparently had not been any tests done to determine whether bees actually consumed the tablets (as opposed to merely removing them due to their irritating thymol content).
Since I had fluorescent tracers on hand that I use to track the ingestion of pollen sub, it wouldn’t be hard for me to confirm whether the bees actually ingest the sugary tablets, or merely carry them away due to their irritating thymol scent (ingestion would be necessary for nutritional benefit, but either ingestion or removal could affect varroa).
We ran two trials on different pairs of colonies (so four replicates in total), pulverizing Apitablets, adding fluorescent tracers, and then forming them back into tablets (Figures 14-17).
Fig. 14 In my high-tech lab, I used the hatchet next to my woodstove to crush each Apitablet in a plastic bag, so that we could then powder it further in my coffee grinder.
Fig. 15 We then added fluorescent tracer (green in this case) to the powdered Apitablet, and homogenized it thoroughly.
Fig. 16 I kneaded in a little water to moisten the mixture, formed it into patties, and allowed them to dry back into solid patties.
Fig. 17 Dried fluorescent-tagged patties glowing under black light, ready for application!
Following the manufacturer’s recommendation for springtime application of Apitablets, I applied the fluorescent patties (now thinner than the original Apitablets for better bee exposure) to pairs of colonies, first at home, then to those placed in an almond orchard in full bloom (Figure 18).
Fig. 18 We placed the test “tablets” in the centers of the clusters, along with black plastic sheets on the bottom boards to catch any removed tablet debris.
In the almond orchard, I took samples of bees from adjacent to the “tablets” after a day, then again after five days, during which time it rained for two days, so the colonies interacted with the “tablets” both during pollen flow as well as when they were confined by rain. I brought the bottom board catch sheets and bee samples home for analysis under blacklight (Figures 19 & 20).
Fig. 19 Here’s a shot of a typical black plastic catch sheet from a bottom board, demonstrating that in all cases, the bees removed a substantial portion of the “tablets” and dropped them to the bottom.
Practical application: Similar to as with Apiguard gel, this transport of thymol down through the broodnest might kill varroa mites.
Fig. 20 We crushed paired samples of bees from both hives to expose their gut contents, then photographed them under blacklight (Day 1 above, Day 5 below). The glowing green blotches indicate ingested portions of the Apitablets.
Although in the lower photo two bees clearly had swallowed a substantial amount of Apitablet, overall ingestion was sporadic and rather minimal.
Conclusions
Although in this trial the feeding of Apitablets to our Test group did not indicate a benefit in either colony strength or mite suppression, some other beekeepers have given glowing reports (“««««« Highly recommended! It is easy to use and it works”). Plus the study by Cengiz indicated that feeding thymol in a sugar cake could be efficacious, although his patties were 10% thymol — suggesting that the action may have been due to fumigation, as opposed to ingestion (which would likely be toxic to the bees).
So I’m still of open mind about the benefits of Apitablets. This was a single trial performed during hot, dry autumn weather in California — results may be different in your locale. I’d appreciate seeing data from others who have tested them!
I’ll likely follow up with another trial this spring, since the claim is that “A well-timed application of Apitablet in early spring infuses the hives with a boost of essential nutrients, setting the stage for robust brood development and vigorous foraging activities”.
Acknowledgements
Thanks to my helpers Corrine Jones and Rose Pasetes, and to you donors who make our work possible.
Citations and Notes
[1] Sammataro, D, et al (2009). Feeding essential oils and 2-heptanone in sugar syrup and liquid protein diets to honey bees (Apis mellifera L.) as potential Varroa mite (Varroa destructor) controls. Journal of Apicultural Research 48(4): 256-262.
[2] Charpentier, G, et al (2014). Lethal and sub‐lethal effects of thymol on honeybee (Apis mellifera) larvae reared in vitro. Pest Management Science 70(1): 140-147.
Glavan, G, et al (2020). Comparison of sublethal effects of natural acaricides carvacrol and thymol on honeybees. Pesticide Biochemistry and Physiology 166: 104567.
[3] Aboushaara, H, et al (2017). Impacts of oxalic acid, thymol, and potassium citrate as Varroa control materials on some parameters of honey bees. Turkish Journal of Veterinary & Animal Sciences 41(2): 238-247.
[4] Cengiz, M. (2018) Effectiveness of combining certain biotechnical methods with thymol treatment against Varroa destructor infestation. African Journal of Agricultural Research 13(47): 2735-2740.
“For the treatment with thymol, bee cake was prepared (18 kg Ice sugar + 3 kg honey + 400 g pollen + 2 L water). Ten grams of powdered thymol was added to 90 g of the bee cake”.
[5] https://apimonllc.com/insights/why-choose-apitablet-benefits-of-a-natural-honey-bee-food-supplement
[6] https://scientificbeekeeping.com/thymol-a-new-application-method-part-1/