The optimum launch fee and location of thymol 1
Thymol — A brand new utility approach?
Phase 2
First revealed in ABJ in December 2022
Randy Oliver
ScientificBeekeeping.com
I do a large number of experimentation in beekeeping, incessantly induced through questions or concepts from different beekeepers. This spring a beekeeper confirmed me a do-it-yourself thymol concoction, which jogged my memory to pick out again up on some earlier thymol analysis of my very own.
Prolonged-release thymol
Remaining month I raised the query of whether or not shall we use a ½” thick cellulose matrix (Homasote [[1]]) with a purpose to throttle the evaporation fee of a thymol remedy over an extended time frame, thus permitting us download efficacious mite relief with just a unmarried utility.
A systematic observe: Ahead of making an investment time in large-scale managed trials, I in most cases first carry out some initial “fast and grimy” experimentation, as detailed right here [[2]]. Now not wanting to apply a inflexible protocol, this opens the door for advert hoc experimentation and unanticipated discoveries, which might then lead me in new instructions.
The optimum launch fee and location of thymol
I’ve discussed that bees don’t maintain the smell of thymol, and if a remedy is positioned above the cluster, they are going to construct a wall of propolis round it (Determine 1).
Fig. 1. If the bees are not able to take away a substrate with a powerful smell of propolis, they are going to try to duvet or wall it off with a layer of propolis. Of passion, I didn’t follow any colony doing this with the Homasote blocks.
Sensible observe: A powerful thymol remedy implemented throughout the cluster will also be very disruptive to the colony, inflicting the bees to noisily try to fan the smell away, uncap and take away brood (with plenty of white pupae appearing up at the backside board), or within the worst case, the colony might utterly abscond from the hive.
I discovered that it’s now not simply the dose, however relatively the quantity of floor house from which the thymol (with its low vapor drive) is in a position to evaporate. Thus, utility through thymol-saturated store towels, with their broad floor house relative to quantity, leads to too speedy launch of the thymol (particularly when implemented between the brood chambers, because of the bees intensely fanning air over the towel surfaces).
Thymol on a store towel can be a “flash” remedy. Alternatively, the registered thymol formulated merchandise follow thymol in an extended-release way.
Sensible utility: However even the ones merchandise require no less than two packages. So I puzzled whether or not with a purpose to save the exertions fascinated about reapplication, is there a strategy to lengthen the discharge of a bigger dose?
What’s The Optimum Dose?
Thymol will also be implemented as a flash remedy to broodless colonies, with maximum mites losing inside a couple of hours of utility. Chiesa [[3]] sprinkled 1 gram of powdered thymol over the tops bars of broodless colonies, 4 instances, at 2-day durations, and bought over 95% mite kill, particularly if the powdered thymol was once blended with powdered sugar. So 4 g of thymol seems to be sufficient to kill the mites in a colony now not containing brood.
But if colonies include brood, it it appears takes a bigger dose, delivered over a length of weeks relatively than days. Let’s check out the collection of grams of thymol according to dose of the registered merchandise (the purple numbers in Desk 1).
| Desk 1. The per-application dose of registered thymol formulated merchandise. | ||||
| Product title | Dose of thymol according to utility | Retreatment period and collection of packages | Supply matrix | Different elements |
| Apiguard | 12.5g for full-strength colonies, part that once temperature is above 77°F | Repeat at 1-2 week durations for 4-6 weeks | Polyacrylate “gel” in water | None |
| ApiLifeVar | 8g | Repeat 3x (some directions say 4x) at 7-10 days |
Vermiculite | Eucalyptol, menthol, and camphor |
| Thymovar | 15g will also be ramped up in sizzling climate | Take away after 3-4 weeks, pause for 1 week, then reapply | Cellulose sponge | None |
It appears to be like as although a colony with brood can take care of 6-12 grams of slow-release thymol every week. Since I’d already decided that 5.1 sq. inches of Homasote will hang 12 g of thymol (after soaking up a saturated resolution of thymol in ethanol), it was once a easy subject to precut blocks of Homasote to carry any dose of thymol that I sought after to check. I made up our minds to use 4 blocks of Homasote according to hive, so I calculated how broad to chop every block to score every desired dose according to hive (Desk 2).
Our Box Checking out
It was once overdue August after we began this venture, so sadly after I requested my sons as to the provision of colonies with excessive mite counts through which I may take a look at those experimental thymol remedies, they stated that every one their 1500 colonies had the mites neatly underneath keep an eye on, with mite wash counts (according to part cup of bees) within the 0-2 vary. This was once nice for them, however unhealthy for me.
So the one colonies with excessive sufficient mite ranges to make use of for trying out had been the hives left in 3 yards through which Rose and I had in the past examined formic and oxalic remedies, a few of which nonetheless had measureable mite infestations. So we began trying out to peer how the colonies reacted, in sizzling climate, to having a 12-gram dose of thymol positioned proper between the brood chambers (Determine 2).
Fig. 2. My assistant Rose Pasetes (dressed in correct protecting equipment in opposition to the solar) appearing the position of 4 blocks (this photograph is of a average dose). The bees to start with moved clear of the fumes, so it’s now not obtrusive on this photograph that the hive was once stuffed with bees and brood.
We implemented the 12-g dose to 6 hives. To our nice marvel, inside an afternoon the bees acted as although the thymol wasn’t even there. Lets scent the fumes after we opened the hives, however there was once no fanning, and no obvious impact upon broodrearing (Determine 3).
Fig. 3. Once more, the next dose, however appearing the loss of disturbance to the bees on this freshly-opened hive.
Shocked and emboldened through the loss of bee reaction to the 12-g dose, we implemented 24-g doses to seven colonies, some with the blocks implemented between the brood chambers, some in a rim above the second one brood chamber (Determine 4).
Fig. 4. Standard placement of thymol blocks in a rim.
I opened the colonies incessantly to check up on for one of these brood disruption I used to be aware of seeing all the way through a thymol remedy, however even with the 24-gram dose I didn’t see anyplace up to I anticipated. So what the heck — we made up some extra blocks with a purpose to follow 36-g doses to seven further colonies.
All over this ongoing experimentation, I used to be ready to watch what the bees did because the depth of the thymol fumes wore off within the first hives. As I’d famous in my experiments in 2017, maximum colonies started chewing away on the blocks, relatively than propolizing them over (Figures 5 & 6).
Fig. 5. The blocks nonetheless scent of thymol after 3 weeks, however the bees don’t seem to be through it through that point. As soon as the thymol fume depth lowered, the bees in lots of the hives began chewing away on the blocks. There have been in fact broad colony-to-colony variations within the quantities of propolization and chewing elimination, however this photograph is standard.
Fig. 6. Observe how the place evaporation was once inhibited through the blocks being squeezed between the highest and backside bars, that there was once chewing best at the edges.
What stunned me maximum about this experiment was once how little the colonies seemed to be through those high-dose remedies. There was once no noticeable fanning, and after an preliminary suppression of the rearing of younger larvae, maximum colonies briefly resumed the rearing of all phases of brood within the middle frames — regardless of whether or not the blocks had been positioned between or above the brood chambers.
I used to be even daring sufficient to use 48 grams of thymol, in a rim, making use of the remedy to a powerful double on 27 July, with temperatures incessantly within the excessive 90sF (Figures 7 & 8).
Fig. 7. Photograph on 17 August — 21 days after utility of 4 12-gram thymol blocks — of wholesome brood of every age within the decrease brood chamber within the warmth of summer season drought. The forged sealed brood indicated that the larvae were began and reared all the way through essentially the most intense length of thymol evaporation. I may hardly ever consider my eyes! The mite wash depend had long past from 14 mites to 0.
Fig. 8. Similar colony on Oct 9, 74 days after utility of blocks (general 48g of thymol), which through then had no noticeable thymol smell. The mite wash depend was once nonetheless 0, with the colony containing quite a few handsome brood and honey.
Shocked and emboldened through how neatly this colony did with 48 grams of thymol positioned in a rim (and wanting extra information for a dose-response curve), in overdue September I recognized two (sadly) susceptible colonies with measureable mite counts, and positioned 4 12-g blocks between the brood chambers (Determine 9). Climate was once within the 70sF, however quickly rose once more to the 90s. Sadly the nectar and pollen flows had been over, and there was once little broodrearing happening ahead of or all the way through this intense remedy, however I sought after to peer (1) whether or not a 48-gram dose would 0 out the mite counts because it did with the colony above and (2) to peer how susceptible colonies would reply to this extraordinarily excessive dosage of thymol.
Fig. 9. A susceptible colony 4 days after utility of 4 12-g thymol blocks overdue within the season (an deliberately intense take a look at). Because of dearth there wasn’t a lot brood after I implemented the blocks, however even after 4 days of this intense publicity, there have been nonetheless patches of brood of every age on 3 frames within the higher field. Instead of their fast buzz after I had first implemented the strips, the bees didn’t seem to be disrupted through the most obvious smell of thymol – the bees seemed to be performing “in most cases.”
I’m now not about to mention that there was once no antagonistic impact from this robust dose upon the colonies, however I used to be stunned through how the bees gave the impression to briefly acclimate to the smell of thymol within the hive (it was once simple for me to sniff after I opened them). Those two susceptible 48-gram colonies persisted to rear some brood of every age right through the remedy, and their mite wash counts had dropped to 0 through 17 days after utility (one going from a depend of 44 mites to 0).
The Dose-Reaction Curve
I used to be best ready to search out 23 colonies with mite counts excessive sufficient on which to check this technique of thymol utility (having beginning mite wash counts starting from 5 to 44; imply 20, median 18), so this information is best initial and suggestive. With a purpose to estimate a dose-response curve, I calculated % relief of the counts vs. the implemented dose of thymol, in order that I may get an concept as to the optimum dose to check subsequent season (Determine 10).
Fig. 10. The upper the knowledge issues, the easier the mite relief — 100% signifies and finishing depend of 0. A 12-gram dose (divided between 4 blocks) gave inconsistent mite relief, however 48 grams zeroed the counts in all 3 hives. The fewer-intense 36-gram dose is also the optimum goal dose, however it’s now not but transparent whether or not it’s best implemented between the brood chambers or in a rim above (I examined each).
Dialogue
As a long-time consumer of Apiguard, I’m lovely stoked through the ease of this utility approach of thymol in Homasote blocks. I used to be dumbfounded through how mild the 12- and 24-gram doses implemented on this way had been at the bees and brood, and pleasantly stunned through how neatly the colonies treated the 36- and 48-gram doses. I plan on acquiring a allow to make bigger my trying out of this technique subsequent season.
Sensible utility: A very easy-to-apply thymol remedy that calls for just a unmarried utility can be nice to make use of in rotation with oxalic and formic acid.
Observe: This utility approach isn’t licensed within the U.S, however might be utilized by beekeepers in New Zealand or different international locations the place it’s felony.
Addition: Checking the Protection Knowledge Sheet for Homasote, I to find that it comprises a 10th of a % (1000 ppm) copper metaborate (more likely to inhibit mildew and termites).
So this raises the query as as to if that quantity of copper metaborate is of shock so far as antagonistic results upon the bees, or contamination of honey (not going, since we don’t in most cases follow thymol remedies all the way through a honey drift).
The EPA concluded in 2009 that “To be had information from a honey bee acute toxicity find out about indicated that copper is nearly unhazardous to honey bees.” (https://www3.epa.gov/insecticides/chem_search/reg_actions/reregistration/red_G-26_26-Might-09.pdf), it appears based totally upon a unmarried find out about:
Hoxter, Okay. (1988) Copper Hydroxide: An Acute Touch Toxicity Find out about with the Honey Bee: Natural world World Ltd. Venture No. 190- 140. Unpublished find out about ready through Natural world World Ltd. 14 p.
Some degree to remember is that it’s not going {that a} bee would eat any of the Homasote. I didn’t follow any indication of inauspicious results after remedy, however will run some cage trials.
Hladun, Okay.R., Di, N., Liu, T.-X. and Trumble, J.T. (2016), Steel contaminant accumulation within the hive: Penalties for whole-colony well being and brood manufacturing within the honey bee (Apis mellifera L.). Environ Toxicol Chem, 35: 322-329. https://doi.org/10.1002/and many others.3273
Citations and notes
[1] http://www.homasote.com/property/information/homasote-440-sds.pdf
[2] For this off-label experimentation with thymol, I bought a Pesticide Analysis Authorization from the California Division of Pesticide Law, since in contrast to with my earlier analysis that didn’t contain the use of thymol as a miticide, on this case I used to be the use of it for that objective.
[3] Chiesa, F & M D’agaro (1991) Efficient keep an eye on of varroatosis the use of powdered thymol. Apidologie 22(2): 135-145.