Contents
Colony Reaction to the Remedy 6
Is it Price Making ready Your Personal?. 15
Closing Inquiries to Solution 15
There’s a Reason why that EPA Registers Miticides! 16
Prolonged-Unencumber Thymol Blocks
Randy Oliver
ScientificBeekeeping.com
First revealed in ABJ April 2024
Since varroa mites spend kind of 70% in their time beneath the cappings, miticides are maximum efficacious if implemented in an extended-release method —which exposes the mites to the remedy whilst they’re of their dispersal section. With reference to thymol, gradual launch is completed by way of dissolving it in oil, or embedding it in absorbent strips or aqueous gel. However the entire currently-registered thymol merchandise launch their vapors slightly temporarily, and thus require repeated programs.
In 2022 I revealed the result of my experimentation (beneath allow) of a unique manner of making use of this biopesticide [[1]]. Because the EPA has now said that it does now not prohibit “personal use” of generic thymol, we beekeepers could also be in a position persuade our State Lead Businesses to practice swimsuit and make allowance us to make use of this system.
My Initial Findings
I had up to now decided colony tolerance of slow-release thymol, in addition to a dose/reaction curve (Determine 1).
Fig. 1. My initial analysis urged that the optimum dose of thymol to use by way of this system can be round 40 grams –– much less in general than the volume allowed by way of the label of Apiguard (as much as 4 weekly programs of 12.5 grams). In order that’s what I examined remaining summer season.
Preparation
I had in the beginning experimented with Homasote fiberboard (created from recycled newspaper [[2]]), however had bother discovering it in California, so additionally examined an to be had acoustic soundboard created from wooden fiber [[3]]. I dissolved USP-grade thymol [[4]] in denatured alcohol on the ratio of one gram of thymol crystals to one mL of alcohol (the thymol dissolves temporarily if the alcohol is moderately warmed and stirred). This creates a nearly-saturated answer that comprises ~0.6 grams of thymol in line with milliliter of answer.
Approach
Let’s say that you simply sought after to regard 5 hives, so that you’d want 4 blocks in line with hive x 5 hives = 20 blocks in general.
Step 1: Use a desk noticed to chop twenty 1” x 4” blocks from ½”-thick wooden soundboard (1” x 4¾” for Homasote) and position them upright on finish, side-by-side in a container. Vital observe: those dimensions are for thymol dissolved in denatured alcohol as above (see the observe underneath).
Step 2: Then combine up your thymol approach to fit the collection of blocks. For 20 blocks, every to carry 10 g of thymol (40 g in line with hive), dissolve 20 x 10 g = 200 g of thymol crystals into an equivalent collection of milliliters (200 mL) of alcohol.
Step 3: Pour the answer into the container in order that the blocks calmly soak up it (Determine 2).
Fig. 2 Since you made the blocks longer than important for complete absorption, they’ll utterly suck up the entire answer. Since you understand how a lot general thymol you added, then you definitely know the way a lot thymol (on moderate) every block absorbed. Easy!
Notice: I used denatured alcohol (ethanol normally with 10% methanol). As a result of ethanol is of course produced throughout the fermentation of beebread (and because bees like ethanol), and because I allowed the alcohol to evaporate off previous to putting the blocks into hives, I wasn’t eager about contamination of my combs. Alternatively, ethanol isn’t at the Minimum Chance Inerts checklist, so whilst writing this newsletter, I bought some 99.9% isopropyl alcohol (which is at the Checklist), assuming that it might dissolve thymol in a similar way to denatured alcohol. As soon as once more, such a lot for assumptions!
I pulled out the dimensions and graduated cylinders, and went to the lab (my kitchen) to check the 2:
Saturated answers
50g thymol + 50 mL denatured alcohol = 85 mL saturated answer
50 g thymol + 100 mL 99.9% isopropyl alcohol (heated) = 128 mL moderately supersaturated answer
Sensible utility: Thymol isn’t practically as soluble in isopropyl alcohol as it’s in ethanol or methanol! In the event you use isopropyl, you’ll want to reduce your blocks a minimum of 50% longer.
Replace: I used to be in truth stunned once I got here up with the struck-through determine above once I blended up an answer as a take a look at in a while prior to I despatched this newsletter off for newsletter, since my reminiscence was once that I had all the time get a hold of ~100 mL once I’d up to now blended it.
The adaptation may were because of my the usage of a unique logo of alcohol, since when these days I blended up a recent batch of 1000 grams of thymol to 1000 mL of denatured alcohol from a recent can of a unique logo, I bought 2070 mL of answer.
So ~21 mL answer/10g of thymol
So for a 40 g dose in line with hive, position 4 ½” x 1” x 4” blocks right into a pan or jar and upload 84 mL (4 x 21) of answer. The blocks will suck all of it up.
As soon as the blocks have absorbed the answer, unfold them out and make allowance the alcohol to flash off. For speedy evaporation, unfold out the blocks in one layer over a display screen –– within the solar or a heat ventilated position. It frequently takes lower than an hour for the alcohol to evaporate off.
A tip: In the event you write down the beginning weight of a block prior to absorption, you’ll be able to reweigh them because the alcohol evaporates, till the blocks weigh most effective moderately over 10 grams greater than they began at (because of the added weight of the thymol) –– it’s now not important to totally evaporate the alcohol.
A commonplace false impression: It’s a commonplace false impression that thymol is very unstable. It isn’t! At 77°F (25°C), the vapor drive of thymol is most effective 0.016 mm of mercury, while the vapor drive of ethanol is 59 mm Hg). Just about the entire alcohol will evaporate off prior to a measurable quantity of thymol does! As soon as lots of the alcohol has evaporated, the blocks will also be saved in a sealed plastic bag or different hermetic container (Determine 3).
Fig. 3 The blocks (Homasote at the left, wooden soundboard to the suitable) are right here packed for garage after drying.
Software to The Hives
We starte the sphere trial close to the top of July, in sizzling, dry climate (Determine 4).
Fig. 4 Within the California foothills, our honey float is normally over by way of the top of July, offering us a window of alternative to get rid of varroa prior to we begin feeding pollen sub to stimulate brood rearing in mid-September. I sought after to peer how a unmarried utility of thymol blocks in comparison to the 2 rounds of Apiguard that we’ve used up to now (which actually disrupted brood rearing in sizzling climate).
Sadly, because of my sons’ a success mite control up to now, we had to carry out numerous mite washes to search out sufficient hives (34) with mite counts prime sufficient to make use of for the trial (so the experiment was once divided between 5 other yards, offering replication). The entire check colonies have been in double deeps, normally with brood in each containers. We used a randomized block design, blockading by way of the beginning mite counts for every backyard, to randomly assign whether or not a colony would obtain Homasote or wooden fiber blocks. 4 colonies had excessively prime mite counts, so I implemented blocks containing a complete of 48 grams of thymol to them to peer how they’d care for the upper dose.
We used a 1½-inch rim atop every hive, and positioned 4 thymol blocks within the corners (Determine 5).
Fig. 5 We changed our darkish plywood migratory covers over the edges. Noon temperatures of the tops of the covers reached 160°F (120°F at the undersides), so the thymol gained a lot of warmth to force evaporation.
Colony Reaction to the Remedy
Throughout the 21 days of remedy (moderately over one complete bee brood cycle [[5]]), we inspected the hives incessantly. There was once really extensive variation in how every colony reacted to the remedy (Figures 6-12).
Fig. 6 Maximum colonies ceased rearing younger brood within the higher chamber, however persisted unabated underneath.
Fig. 7 After which they began storing nectar from the sunshine float (or from jars of syrup in some yards) within the former brood cells (you’ll be able to simply catch the glisten on this photograph). I preferred this, since we would like the field above the cluster to be full of honey (herbal or from syrup), previous to iciness.
Fig. 8 In lots of the hives, the queen not noted the fumes and stuffed empty cells within the higher chamber with eggs, however we frequently noticed them now not growth to the larval level (we couldn’t inform whether or not the eggs died, or the nurses cannibalized them).
Fig. 9 To not be outdone, a few colonies utterly not noted the fumes, constructed recent comb within the rim, and regularly reared brood proper as much as the blocks!
Fig. 10 The bees normally left the thymol blocks on my own, most effective construction propolis “shells” round a couple of. Handiest after 3 weeks did any start chewing them.
Fig. 11 Our maximum unexpected remark was once that each and every colony maintained persistent brood rearing throughout the 21-day remedy — maximum of them principally within the decrease field.
Fig. 12 In contrast to as with Apiguard –– the debris of which the bees elevate down in the course of the brood house, a great deal disrupting brood rearing –– there was once all the time a lot of brood of every age in each and every hive at each and every inspection.
We ended the trial after 21 days, through which time the thymol had in large part evaporated from the blocks, and maximum colonies had begun brood rearing within the higher chamber once more (Determine 13).
Ultimate Inspection
Fig. 13 Corrine Jones helped me with ultimate inspections. The sealed brood on this body is a minimum of 12 days outdated — indicating that the nurses have been accepting and feeding larvae within the higher field midway in the course of the remedy. We have been stunned by way of the volume of brood rearing that came about throughout the recent, dry August pollen dearth (in comparison to our lengthy enjoy with Apiguard).
We didn’t follow any queen losses or different notable hostile results upon the colonies.
Impact upon Varroa
The colonies fared unusually smartly; I will be able to’t say the similar for the unlucky mites (Determine 14).
Fig. 14 It didn’t take lengthy to rely the mites within the ultimate mite washes! We counted 851 initially, and most effective 14 on the finish –– a 98% aid. The consequences have been constant from backyard to backyard (now not proven).
Sensible utility: This is without doubt one of the maximum efficacious [[6]] remedies I’ve ever observed for colonies with brood, and it most effective took a unmarried utility and 3 weeks period, leaving the colonies powerful and thriving.
I tracked the colonies for the remainder of the season. There was once no bounce-back of mites, and the colonies went into iciness in nice situation.
Is it Price Making ready Your Personal?
There’s a hard work saving from with the ability to most effective follow a unmarried utility for a three-week remedy with few hostile results, nevertheless it takes some effort and time to arrange the blocks. Right here’s a breakdown of estimated prices (now not together with delivery), the usage of costs from the web and Wintersun Chemical (a big business provider of USP-grade commercial chemical substances that we discover simple to paintings with)(Desk 2).
Desk 2. Sadly, off-the-shelf thymol is pricey in small amounts. The price of the soundboard is negligible in amount, so I didn’t come with it, nor did I come with any delivery prices.
A Closing Query
I puzzled what distinction it might make if I implemented the remedy later within the season, in cooler climate, whilst we have been seeking to develop vulnerable colonies by way of feeding syrup and sub in past due September?
So I waited till the elements cooled, and handled two very vulnerable colonies with average mite counts, positioned within the colour. They took syrup and pollen sub eagerly throughout remedy, however they didn’t develop a lot (however no colonies have been rising a lot at the moment). The stage of mite aid wasn’t nice. The thymol blocks (most likely at a decrease dose) would possibly want to be positioned between the brood chambers in cooler climate.
Sensible utility: Those blocks can certainly be positioned between the brood chambers, however I’ve most effective initial observations from a couple of check colonies, and most effective throughout the summer season. They seemed to tolerate as much as 36 grams of thymol smartly. Please let me know your effects if you happen to take a look at other placements, time of yr, or utility strategies!
There’s a Reason why that EPA Registers Miticides!
An hostile impact file: I simply heard these days from a southeastern beekeeper who implemented 36 grams of thymol to singles in heat springtime climate, and noticed some queen kills –– most likely because of that being too robust a dose for singles.
Within the registration means of any miticide, the EPA will pay nice consideration to the method and the label, to make certain that utility of a registered miticide by way of the finish consumer does now not pose an unreasonable chance to the general public, the surroundings, the bee colony itself, or to the applicator (you). Needless to say crops create oxalic acid, formic acid, thymol, and crucial oils as poisons — you’ll be able to’t simply move about making use of them willy-nilly.
Sensible utility: Thymol implemented at too prime a price of launch, relative to temperature, hive measurement, and colony energy, can kill bees and brood — main points are essential! My check was once on double deeps, and with the 40-gram dose in a rim on best. In case your state lets in use of unregistered miticides, practice examined strategies of utility, or experiment very in moderation on only some hives.
Citations and Notes
[1] Thymol — A brand new utility formula? Phase 2. American Bee Magazine December 2022 https://scientificbeekeeping.com/thymol-a-new-application-method-part-2/
[2] Homasote 440 Medium Density Fiber Board; (94-98% paper cellulose, 1-6% paraffin wax, <0.1% copper metaborate (Homasote was once licensed by way of EPA for the Miteaway II pads).
[3] ½-inch Sound deadening panel, Construction Merchandise of Canada Corp. “comprised of non-toxic natural subject material and herbal wooden fibres which can be wax impregnated.”
[4] From Wintersun Chemical www.wintersunchem.com
[5] A bee brood cycle averages ~20 days in sizzling climate), while a varroa reproductive cycle is normally round 17 days throughout energetic broodrearing.
[6] Technically I couldn’t calculate efficacy, since I didn’t run a keep an eye on crew.