Selective Breeding Growth Record 2023

Table of Contents

Selective Breeding Growth Record 2023

Randy Oliver

ScientificBeekeeping.com

First revealed in ABJ September 2023

In 2017 I proposed a simplified manner for industrial queen breeders to choose for varroa-resistant inventory, after which undertook an indication challenge to peer if it could paintings. After six years of sturdy variety, we seem to be making considerable growth!

In 2017 I revealed the item “Bee Breeding for Dummies,” [[1]] lamenting that we’d been scuffling with varroa for over 3 a long time, but maximum queen manufacturers had been nonetheless no longer providing mite-resistant inventory. I described “Randy’s Ok.I.S.S. Recipe For Business Queen Manufacturers,” and adopted up in 2018 with “Selective Breeding for Mite Resistance: 1000 hives, 100 hours,” [[2]] during which I stored observe of the volume of work concerned, the prices, and an analysis of our effects all the way through the primary yr.

The Premise for Selective Breeding

Selective breeding is a right away solution to resolve if a particular trait can evolve based on variety [[3]]. I love the best way that E.W. Hill [[4]] describes breeding:

The foundation of genetic development methods in any organism is selective breeding, the place people are selected which can be anticipated to have offspring with fascinating homes. That is directed evolution: health is outlined by way of the breeder somewhat than by way of the person’s talent to live to tell the tale and reproduce in nature.

For selective breeding to be efficient, there will have to be genetic variation provide within the inhabitants, some way of figuring out folks for variety which can be more likely to transmit the specified homes to the descendants, and enough spare reproductive capability in order that the inhabitants will also be bred from simplest the selected folks. For many characteristics there’s really extensive variation on the noticed or phenotypic stage, thus offering various selective alternative.

The basis for our personal selective breeding program for varroa resistance is based totally upon a number of issues (key phrases in boldface):

That during any breeding inhabitants of honey bees, there are possibly a couple of colonies in every era that showcase a mixture of characters (uncapping conduct, hygienic pupal removing, grooming or biting, permutations of their pheromones, social apoptosis, and so forth.) that together, confer the trait of “varroa resistance” upon the colony.
That the combo of characters that confer that trait are heritable ― which means that they may be able to be handed to a brand new colony by the use of the genetics (and epigenetics) of the queen and the sperm that she carries in her spermatheca.
That one can determine which colonies showcase the trait of resistance, by way of taking samples of a part cup of bees from a comb. Understand that it’s no longer the queen this is resistant ― the trait is expressed on the colony stage.
That we will build up the occurrence of the trait of resistance in our breeding inhabitants by way of certain and/or unfavorable choice of the queens of colonies expressing the trait of resistance (breed from those who head resistant colonies, get rid of the ones whose colonies display excessive mite ranges).

Sensible utility: This newsletter is most commonly about my evaluate of our growth, as made up our minds by way of the rise in occurrence of the trait of varroa resistance in our breeding inhabitants

A Transient Description of our Strategies

I’m working this program as an experimental demonstration challenge (“strolling the stroll”) for the good thing about our industrial queen manufacturers. I wish to objectively see how a lot growth one can be expecting to make by way of the usage of a highly-simplified “changed Bond” breeding program, during which no colonies want to be misplaced to varroa, and the one evaluate used for the identity of breeders is mite washes [[5]].

We break up all our hives into nucs after they go back from almond pollination, requeening them with cells from breeders whose colonies exhibited complete resistance the former yr. We observe an oxalic dribble on the brood damage on Day 18 in an effort to get started all of the nucs with quite low mite infestations.

Then in overdue June or July we take mite washes from each and every hive in our operation (which takes about 70 hours of work consistent with 1000 hives), figuring out those who have mite counts of 0 or 1 as “attainable breeders,” and deal with the remaining.

We then proceed to pattern the ones attainable breeders over the process the yr (generally 4-5 occasions). Our maximum resistant colonies have data of five consecutive counts of 0 (and to “make grade” will have to even be delicate and productive).

The following spring we then change all of our queens with daughters grafted from larvae produced by way of queens that had headed colonies that stored mites to close 0 for all of the yr. The ones virgins are then open mated with drones produced by way of the daughters of the former yr’s decided on queens (whether or not their colonies exhibited resistance or no longer ― I’ll go back to this shortcoming).

Every yr I’ve revealed stories on our frustratingly sluggish growth to “repair” the trait of resistance in our breeding inhabitants.

Constraints of the Manner

Our Ok.I.S.S. manner deliberately avoids instrumental insemination, single-drone inseminations, marker-assisted variety, brood dissection, freeze-kill hygiene tests, or monitoring of bloodlines. Any of the ones strategies may just boost up our fee of good fortune, however once more, this demonstration experiment is to resolve what kind of growth we’ll make by way of “conventional breeding,” with out the ones time-consuming or high-tech additions.

Some other constraint is my intentional avoidance of over the top inbreeding, by way of no longer restricting our drone pool to simply the drones produced by way of the present yr’s breeder queens (which might no longer provide sufficient drones anyway), however somewhat by way of permitting the virgins to mate with drones produced by way of the daughters of the former yr’s queens ― all the ones daughters sporting the genetics of queens and drones from earlier generations of decided on breeders.

And we’re no longer simply breeding for resistance ― we breed for inventory that beekeepers would wish to use. So we kick out any resistant colonies that don’t seem to be delicate, sturdy, or productive.

The Low Heritability of the Trait of “Mite Resistance”

It’s quite simple to selectively breed for colour, hygienic conduct, or resistance to tracheal mite, however I’ve no longer discovered it so for the trait of “varroa resistance.” Mite resistance takes position on the colony stage, and looks to have other alleles of a couple of genes concerned. A queen simplest provides part the genetics of a colony, with the a couple of drones that she buddies with randomly supplying a mix of other alleles.

Even after six years of intense variety, we haven’t but observed a queen whose daughters most commonly produced mite-resistant colonies. We’ve but to “repair” the trait in any bloodline or our breeding inhabitants as an entire. This low stage of heritability [[6]] is disappointing, however that doesn’t imply that we’re no longer making growth.

Growth to Date

We began our program once I came about to note “Queen 0,” whose colony held a mite wash depend of 0 over the route of a complete yr, with none therapies by any means. So originally of our program, I’d recognized 1 colony out of 1500 as showing “complete resistance” to varroa. So we began at 0.07% as our baseline occurrence of resistant colonies.

Since then we’ve requeened each and every one in every of our colonies every yr with daughters grafted simplest from colonies showing the facility to take care of mite wash counts at or close to 0 for a complete yr, whilst surrounded with “standard” hives drifting mites into them (the possible breeders get no particular remedy).

Lately, we’ve averaged figuring out round 70 “fully-resistant” colonies that experience made the grade as breeders, grafting from the 30 with the most efficient total traits (this quantity in an effort to keep away from bottlenecking our genetic variety). Seventy out of 1500 works out to 4.5% — a 70x build up within the occurrence of recognized fully-resistant colonies in our operation.

Have I Been Underestimating our Growth?

The important thing phrase is “recognized.” In my replace closing yr [[7]] I wrote: “I latterly learned that we will have been inadvertently kicking a percentage of potentially-resistant colonies out of this system at our first mite wash evaluate in June or July.” It’s because I don’t understand how many potentially-resistant colonies we fail to spot all the way through the essential first spherical of mite washes, since we reject any colonies whose samples display greater than a unmarried mite (in quite a lot of yards we even kick out any colonies with counts above 0). What I’ve noticed is that quite a lot of the ones rejected colonies are ready to carry their counts backpedal to 0 by way of themselves, however we wouldn’t know, since we deal with them in the event that they don’t make the minimize on their first mite wash.

Now not simplest that, however I haven’t been together with the selection of “moderately-resistant” colonies in my growth tests — ones that would possibly simplest want one or two therapies a yr, versus our standard routine of 4.

Sensible utility: “Mite resistance” isn’t a binary sure or no, however somewhat a spread of stage. Many beekeepers can be pleased with colonies that wanted just a little assist to battle the mite.

Via success, I had an opportunity this summer time to research to what extent I’ve been underestimating our growth towards “resistant” inventory ― together with “overpassed resistant” and “moderately-resistant” colonies. I’ve now were given revised numbers for the rise in occurrence of “resistant” colonies in our breeding inhabitants.

Monitoring Rejected Colonies of their 2nd 12 months

Each and every February we take the vast majority of our colonies to almond pollination, protecting just a few of our breeders at the back of (simply in case one thing is going mistaken). After go back from almonds, we break up all our colonies into nucs ― environment apart the ones queens that also made grade as attainable breeders in splits (in order that they don’t swarm). We requeen all our nucs with queen cells from the “easiest” breeders.

Later in the summertime, I generally run quite a lot of box trials to check the efficacy of quite a lot of varroa therapies. For the ones trials, I want to use non-resistant colonies (for evident causes). So this spring I requested my sons, after they had been splitting our hives, to save lots of a couple of hundred second-year queens in nucs made with their very own bees, giving them an oxalic dribble to scale back their beginning infestation charges, and set them apart for me to judge later. They arrange 9 yards with the ones ostensibly non-resistant colonies (since that they had by no means made the minimize as attainable breeders). In early June, the group took mite wash counts to peer to what stage varroa used to be build up in the ones backyard (anxious that they’d be attaining bad ranges). I looked after the result of their counts (selection of mites consistent with part cup of bees) in Desk 1.

Desk 1. Those colonies had been began in early March with splits containing the queens and bees of ostensibly non-resistant colonies that were handled the former season with some aggregate of formic, oxalic, or thymol therapies, after which given an oxalic dribble after we break up them. That they had by way of now most commonly grown to 10-20 frames lined with bees (some as much as 30), and their mites were reproducing unchecked for three ½ months. I looked after their mite wash counts from lowest to very best, highlighting in crimson the ones colonies with dangerously excessive mite counts. The ones excessive counts point out how a lot the mite inhabitants may just build up in non-resistant colonies over this time period. Evaluate the excessive counts to these of the hives that also exhibited mite counts of 0 to 2, in spite of sitting in yards full of the ones high-mite hives.

Interpretation

Selective Breeding Growth Record 2023

Row A (close to the ground of the desk) is the depend of hives within the backyard.

Row B signifies the imply (arithmetical reasonable) mite depend for all of the hives in that backyard.

Row C signifies the median depend (part the counts above, part under).

Row D presentations the share of colonies in that backyard that seem to display a considerable stage of mite resistance (showing an infestation fee of lower than 2%).

Base line: The above information actually were given me questioning whether or not I’ve been underestimating our stage of good fortune in breeding for resistance!

Sensible utility: With the exception of figuring out probably resistant colonies, so far as basing control selections for treating for varroa upon tracking by the use of mite washes, is the variation between the imply and the median mite wash counts. From a control standpoint, the median depend is of extra significance, because the imply mite depend is skewed upward by way of a couple of non-resistant outlier hives with very excessive mite counts (generally round 10%, 13% crimson within the desk above). We discover it less expensive to take mite wash counts for each and every hive, than to waste cash on useless therapies. This one-time intense tracking every season lets in us to focal point our consideration on our “mite manufacturing facility” hives.

The above information stunned me. At this level of time, out of the 496 hives above, it seemed that I’d have bother bobbing up with the 250 demonstrably non-resistant colonies that I wanted for my box trials! (Sure, we had been giggling at ourselves for complaining about having too many hives with negligible mite counts!)

Sensible utility: It befell to me that this knowledge gave me a chance to estimate what the entire fee of “complete to average” resistance used to be in our operation (since we sampled over 300 colonies from a couple of moms, in a couple of yards).

So I allowed the mites to building up for every other month. In mid-July we once more took mite wash samples from 4 of the above yards to make a choice the 216 hives wanted for one in every of my remedy trials, in an effort to file their beginning infestation charges previous to making use of the check therapies.

I arbitrarily made up our minds to exclude any colonies showing a mite wash depend [[8]] that used to be nonetheless lower than 5, since colonies with any such low fee of mite buildup after over 4 months of heavy brood rearing most likely possessed a point of resistance, in spite of no longer having been recognized as attainable breeders the yr earlier than.

Let’s first check out what an anticipated “standard” distribution (the “bell curve”) of mite counts for a backyard in the event that they calmly various from the typical. For Determine I used Excel to generate a regular distribution for 100 hives with a median depend of 16 mites (very similar to our precise averages consistent with backyard), and a regular deviation of three (to check our vary of counts).

Fig. 1 This can be a theoretical standard distribution — in histogram shape, with every column representing the share of hives at every infestation stage (all of the columns in every graph upload to 100%) — of the anticipated percentages of hives at every infestation stage, for a backyard with a median mite wash depend of 16 (standard for our July counts). This form of curve can be anticipated if all of the colonies had the similar stage of mite resistance, with random variation leading to variations in measured mite counts [[9]].

So let’s examine the curve above to the real distributions of mite counts for the 4 yards that we re-sampled in July.

Fig. 2 There used to be nice variation in infestation charges in all of the yards. Be aware how the curve for this backyard is skewed to the left. Kind of 18% of the colonies had mite wash counts within the 0-5 vary, suggesting quite sturdy mite resistance, in spite of there being non-resistant colonies stuffed with mites scattered throughout the backyard.

Fig. 3 The mite counts had been identical on this backyard, with some excessive outliers with very excessive infestation charges.

Fig. 4 On this greater backyard, the distribution seemed much more skewed towards resistance, with the vast majority of colonies showing low counts, and round 28% suggesting sturdy mite resistance.

Fig. 5 Now not simplest used to be this the backyard with essentially the most hives (staged from a number of places). Over 30% of the colonies had mite wash counts of five or much less, once more with some obviously non-resistant “mite factories” scattered amongst them.

Sensible utility: Now upload to the above figures the 4% of colonies that we’d already got rid of as breeders, suggesting that most likely a 3rd of the colonies in our operation (our breeding pool) at the moment are showing a goodly stage of mite resistance! This discovering, to mention the least, could be very encouraging.

An Evaluation of our Growth to Date

With just a 3rd of our colonies showing sturdy resistance, we’re no longer about to assert that we’re but generating mite-resistant inventory — the heritability of the trait nonetheless stays low. However to chart our growth, we will examine the occurrence of resistant colonies to what we began with.

Going again to our beginning baseline of most likely a 10th of a p.c of our colonies showing resistance, the figures above counsel that once six years of selective breeding, we’ve higher the superiority of mite-resistant colonies in our operation by way of 300x. So even though sluggish, that is obviously growth!

Expanding the Selective Force

We’ve been working towards sturdy certain variety (breeding simplest from colonies ready to take care of extraordinarily low mite counts over the process a yr). We’re now going to extend unfavorable variety ― changing the queens of colonies that we determine with excessive mite counts to forestall them from including their drones to subsequent season’s drone pool after we mate out subsequent yr’s queens.

Wrap-up

Varroa remains to be our nemesis, however mite control is getting more straightforward for us yearly. Keep in mind, we haven’t used artificial miticides for 22 years now. My dream is that I’ll are living to peer the day when our bees “take care” of varroa by way of themselves (or with the occasional thymol or natural acid remedy).

Replace

Since writing this newsletter, we’ve taken our October mite wash counts. In a few of our yards, it sounds as if that we’re drawing near 70% of the hives with mite wash counts no longer over 6 (lower than a 2% infestation).

We is also in spite of everything attaining a tip level, the place over 50% of our drone pool comes from resistant colonies.

We’ve been approached by way of our good friend Ray Olivarez, who (after seeing the standard of our hives in almonds) requested whether or not he may just promote manufacturing queens from our inventory. He agreed to supply us a big remoted mating backyard, which shall we load with our personal drone mom hives (permitting us for the primary time to take action only with resistant colonies). This can be a win-win dream come true, since it’s going to let us in spite of everything “repair” the genetics for mite resistance into our inventory. Move your palms!

Disclaimer: I’m no longer working this program to advertise our personal inventory, however somewhat to display to different industrial queen manufacturers take care of a breeding program for resistant bees for their very own or another selected inventory, corresponding to Harbo, VSH, POL line, Russian, Champlain Valley, locally-adapted ferals, or another resistant inventory (apologies if I didn’t come with any individual’s identify). It’s time for our trade to shift to protecting mite-resistant bees!