Selective Breeding Progress Report 2023

Beekeeping

Selective Breeding Progress Report 2023

sharol

January 12, 2024

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Selective Breeding Progress Report 2023

Randy Oliver

ScientificBeekeeping.com

First revealed in ABJ September 2023

In 2017 I proposed a simplified methodology for industrial queen breeders to pick out for varroa-resistant inventory, after which undertook an indication undertaking to see if it might work. After six years of robust choice, we seem like making substantial progress!

In 2017 I revealed the article “Bee Breeding for Dummies,” [[1]] lamenting that we’d been battling varroa for over three a long time, but most queen producers had been nonetheless not providing mite-resistant inventory. I described “Randy’s Okay.I.S.S. Recipe For Industrial Queen Producers,” and adopted up in 2018 with “Selective Breeding for Mite Resistance: 1000 hives, 100 hours,” [[2]] during which I saved monitor of the quantity of labor concerned, the prices, and an analysis of our outcomes throughout the first yr.

The Premise for Selective Breeding

Selective breeding is a direct solution to decide if a selected trait can evolve in response to choice [[3]]. I like the best way that E.W. Hill [[4]] describes breeding:

The premise of genetic enchancment applications in any organism is selective breeding, the place people are chosen which can be anticipated to have offspring with fascinating properties. That is directed evolution: health is outlined by the breeder quite than by the person’s capability to outlive and reproduce in nature.

For selective breeding to be efficient, there should be genetic variation current within the inhabitants, a method of figuring out people for choice which can be more likely to transmit the specified properties to the descendants, and enough spare reproductive capability in order that the inhabitants could be bred from solely the chosen people. For many traits there may be appreciable variation on the noticed or phenotypic stage, thus offering loads of selective alternative.

The premise for our personal selective breeding program for varroa resistance relies upon a number of issues (key phrases in boldface):

That in any breeding inhabitants of honey bees, there are seemingly a couple of colonies in every era that exhibit a mix of characters (uncapping habits, hygienic pupal removing, grooming or biting, variations of their pheromones, social apoptosis, and so forth.) that together, confer the trait of “varroa resistance” upon the colony.
That the mix of characters that confer that trait are heritable ― that means that they are often handed to a brand new colony by way of the genetics (and epigenetics) of the queen and the sperm that she carries in her spermatheca.
That one can establish which colonies exhibit the trait of resistance, by taking samples of a half cup of bees from a comb. Needless to say it’s not the queen that’s resistant ― the trait is expressed on the colony stage.
That we are able to enhance the prevalence of the trait of resistance in our breeding inhabitants by constructive and/or detrimental number of the queens of colonies expressing the trait of resistance (breed from people who head resistant colonies, get rid of these whose colonies present excessive mite ranges).

Sensible software: This text is generally about my evaluation of our progress, as decided by the rise in prevalence 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 undertaking (“strolling the stroll”) for the good thing about our industrial queen producers. I need to objectively see how a lot progress one can count on to make through the use of a highly-simplified “modified Bond” breeding program, during which no colonies must be misplaced to varroa, and the one evaluation used for the identification of breeders is mite washes [[5]].

We cut up all our hives into nucs after they return from almond pollination, requeening them with cells from breeders whose colonies exhibited full resistance the earlier yr. We apply an oxalic dribble on the brood break on Day 18 with a view to begin all of the nucs with comparatively low mite infestations.

Then in late June or July we take mite washes from each hive in our operation (which takes about 70 hours of labor per 1000 hives), figuring out people who have mite counts of 0 or 1 as “potential breeders,” and deal with the remainder.

We then proceed to pattern these potential breeders over the course of the yr (sometimes 4-5 occasions). Our most resistant colonies have data of 5 consecutive counts of zero (and to “make grade” should even be mild and productive).

The following spring we then substitute all of our queens with daughters grafted from larvae produced by queens that had headed colonies that saved mites to close zero for the complete yr. These virgins are then open mated with drones produced by the daughters of the earlier yr’s chosen queens (whether or not their colonies exhibited resistance or not ― I’ll return to this shortcoming).

Annually I’ve revealed experiences on our frustratingly sluggish progress to “repair” the trait of resistance in our breeding inhabitants.

Constraints of the Methodology

Our Okay.I.S.S. methodology deliberately avoids instrumental insemination, single-drone inseminations, marker-assisted choice, brood dissection, freeze-kill hygiene assessments, or monitoring of bloodlines. Any of these strategies might speed up our price of success, however once more, this demonstration experiment is to find out what kind of progress we’ll make by “conventional breeding,” with out these time-consuming or high-tech additions.

One other constraint is my intentional avoidance of extreme inbreeding, by not limiting our drone pool to solely the drones produced by the present yr’s breeder queens (which couldn’t provide sufficient drones anyway), however quite by permitting the virgins to mate with drones produced by the daughters of the earlier yr’s queens ― all these daughters carrying the genetics of queens and drones from earlier generations of chosen breeders.

And we’re not simply breeding for resistance ― we breed for inventory that beekeepers would need to use. So we kick out any resistant colonies that aren’t mild, robust, or productive.

The Low Heritability of the Trait of “Mite Resistance”

It’s comparatively simple to selectively breed for coloration, hygienic habits, or resistance to tracheal mite, however I’ve not discovered it so for the trait of “varroa resistance.” Mite resistance takes place on the colony stage, and seems to have totally different alleles of a number of genes concerned. A queen solely provides half the genetics of a colony, with the a number of drones that she mates with randomly supplying a mix of various alleles.

Even after six years of intense choice, we haven’t but seen a queen whose daughters largely produced mite-resistant colonies. We’ve but to “repair” the trait in any bloodline or our breeding inhabitants as an entire. This low diploma of heritability [[6]] is disappointing, however that doesn’t imply that we’re not making progress.

Progress to Date

We began our program after I occurred to note “Queen Zero,” whose colony held a mite wash rely of zero over the course of a whole yr, with none remedies in anyway. So at first of our program, I’d recognized 1 colony out of 1500 as exhibiting “full resistance” to varroa. So we began at 0.07% as our baseline prevalence of resistant colonies.

Since then we’ve requeened each one in all our colonies every year with daughters grafted solely from colonies exhibiting the power to keep up mite wash counts at or close to zero for a whole yr, whereas surrounded with “regular” hives drifting mites into them (the potential breeders get no particular therapy).

In recent times, we’ve averaged figuring out round 70 “fully-resistant” colonies which have made the grade as breeders, grafting from the 30 with one of the best total traits (this quantity with a view to keep away from bottlenecking our genetic range). Seventy out of 1500 works out to 4.5% — a 70x enhance within the prevalence of recognized fully-resistant colonies in our operation.

Have I Been Underestimating our Progress?

The important thing phrase is “recognized.” In my replace final yr [[7]] I wrote: “I lately realized that we might have been inadvertently kicking a proportion of potentially-resistant colonies out of this system at our first mite wash evaluation in June or July.” It is because I don’t know what number of potentially-resistant colonies we fail to establish throughout the important first spherical of mite washes, since we reject any colonies whose samples present greater than a single mite (in numerous yards we even kick out any colonies with counts above zero). What I’ve noticed is that numerous these rejected colonies are in a position to carry their counts again all the way down to zero by themselves, however we wouldn’t know, since we deal with them in the event that they don’t make the lower on their first mite wash.

Not solely that, however I haven’t been together with the variety of “moderately-resistant” colonies in my progress assessments — ones which may solely want one or two remedies a yr, versus our regular routine of 4.

Sensible software: “Mite resistance” isn’t a binary sure or no, however quite a spread of diploma. Many beekeepers could be proud of colonies that wanted solely slightly assist to struggle the mite.

By luck, I had an opportunity this summer season to research to what extent I’ve been underestimating our progress towards “resistant” inventory ― together with “neglected resistant” and “moderately-resistant” colonies. I’ve now obtained revised numbers for the rise in prevalence of “resistant” colonies in our breeding inhabitants.

Monitoring Rejected Colonies of their Second 12 months

Each February we take practically all of our colonies to almond pollination, protecting just a few of our breeders behind (simply in case one thing goes unsuitable). After return from almonds, we cut up all our colonies into nucs ― setting apart these queens that also made grade as potential breeders in splits (in order that they don’t swarm). We requeen all our nucs with queen cells from the “finest” breeders.

Later in the summertime, I sometimes run numerous discipline trials to check the efficacy of varied varroa remedies. For these trials, I would like to make use of non-resistant colonies (for apparent 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 cut back their beginning infestation charges, and set them apart for me to judge later. They arrange 9 yards with these ostensibly non-resistant colonies (since they’d by no means made the lower as potential breeders). In early June, the crew took mite wash counts to see to what diploma varroa was increase in these yard (fearful that they’d be reaching harmful ranges). I sorted the outcomes of their counts (variety of mites per half cup of bees) in Desk 1.

Desk 1. These colonies had been began in early March with splits containing the queens and bees of ostensibly non-resistant colonies that had been handled the earlier season with some mixture of formic, oxalic, or thymol remedies, after which given an oxalic dribble once we cut up them. That they had by now largely grown to 10-20 frames coated with bees (some as much as 30), and their mites had been reproducing unchecked for 3 ½ months. I sorted their mite wash counts from lowest to highest, highlighting in pink these colonies with dangerously excessive mite counts. These excessive counts point out how a lot the mite inhabitants might enhance in non-resistant colonies over this time period. Evaluate the excessive counts to these of the hives that also exhibited mite counts of zero to 2, regardless of sitting in yards full of these high-mite hives.

Interpretation

Row A (close to the underside of the desk) is the rely of hives within the yard.

Row B signifies the imply (arithmetical common) mite rely for all of the hives in that yard.

Row C signifies the median rely (half the counts above, half under).

Row D exhibits the share of colonies in that yard that seem to exhibit a considerable diploma of mite resistance (exhibiting an infestation price of lower than 2%).

Backside line: The above information actually obtained me questioning whether or not I’ve been underestimating our diploma of success in breeding for resistance!

Sensible software: Except for figuring out probably resistant colonies, so far as basing administration choices for treating for varroa upon monitoring by way of mite washes, is the distinction between the imply and the median mite wash counts. From a administration perspective, the median rely is of extra significance, because the imply mite rely is skewed upward by a couple of non-resistant outlier hives with very excessive mite counts (sometimes round 10%, 13% pink within the desk above). We discover it cheaper to take mite wash counts for each hive, than to waste cash on pointless remedies. This one-time intense monitoring every season permits us to focus our consideration on our “mite manufacturing facility” hives.

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

Sensible software: It occurred to me that this information gave me a possibility to estimate what the general price of “full to reasonable” resistance was in our operation (since we sampled over 300 colonies from a number of moms, in a number of yards).

So I allowed the mites to construct up for an additional month. In mid-July we once more took mite wash samples from 4 of the above yards to decide on the 216 hives wanted for one in all my therapy trials, with a view to report their beginning infestation charges previous to making use of the take a look at remedies.

I arbitrarily determined to exclude any colonies exhibiting a mite wash rely [[8]] that was nonetheless lower than 5, since colonies with such a low price of mite buildup after over 4 months of heavy brood rearing seemingly possessed some extent of resistance, regardless of not having been recognized as potential breeders the yr earlier than.

Let’s first check out what an anticipated “regular” distribution (the “bell curve”) of mite counts for a yard in the event that they evenly assorted from the typical. For Determine I used Excel to generate a traditional distribution for 100 hives with a mean rely of 16 mites (much like our precise averages per yard), and an ordinary deviation of three (to match our vary of counts).

Fig. 1 It is a theoretical regular distribution — in histogram kind, with every column representing the share of hives at every infestation stage (all of the columns in every graph add to 100%) — of the anticipated percentages of hives at every infestation stage, for a yard with a mean mite wash rely of 16 (typical for our July counts). This form of curve could be anticipated if all of the colonies had the identical diploma of mite resistance, with random variation leading to variations in measured mite counts [[9]].

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

Fig. 2 There was nice variation in infestation charges in all of the yards. Observe how the curve for this yard is skewed to the left. Roughly 18% of the colonies had mite wash counts within the 0-5 vary, suggesting comparatively robust mite resistance, regardless of there being non-resistant colonies filled with mites scattered throughout the yard.

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

Fig. 4 On this bigger yard, the distribution seemed much more skewed towards resistance, with the vast majority of colonies exhibiting low counts, and round 28% suggesting robust mite resistance.

Fig. 5 Not solely was this the yard with essentially the most hives (staged from a number of areas). Over 30% of the colonies had mite wash counts of 5 or much less, once more with some clearly non-resistant “mite factories” scattered amongst them.

Sensible software: Now add to the above figures the 4% of colonies that we’d already eliminated as breeders, suggesting that maybe a 3rd of the colonies in our operation (our breeding pool) at the moment are exhibiting a goodly diploma of mite resistance! This discovering, to say the least, could be very encouraging.

An Evaluation of our Progress to Date

With solely a 3rd of our colonies exhibiting robust resistance, we’re not about to assert that we’re but producing mite-resistant inventory — the heritability of the trait nonetheless stays low. However to chart our progress, we are able to examine the prevalence of resistant colonies to what we began with.

Going again to our beginning baseline of maybe a tenth of a p.c of our colonies exhibiting resistance, the figures above recommend that after six years of selective breeding, we’ve elevated the prevalence of mite-resistant colonies in our operation by 300x. So though sluggish, that is clearly progress!

Rising the Selective Strain

We’ve been training robust constructive choice (breeding solely from colonies in a position to keep extraordinarily low mite counts over the course of a yr). We’re now going to extend detrimental choice ― changing the queens of colonies that we establish with excessive mite counts to forestall them from including their drones to subsequent season’s drone pool once we mate out subsequent yr’s queens.

Wrap-up

Varroa continues to be our nemesis, however mite administration is getting simpler for us yearly. Bear in mind, we haven’t used artificial miticides for 22 years now. My dream is that I’ll dwell to see the day when our bees “take care” of varroa by themselves (or with the occasional thymol or natural acid therapy).

Replace

Since writing this text, we’ve taken our October mite wash counts. In a few of our yards, it seems that we’re approaching 70% of the hives with mite wash counts not over 6 (lower than a 2% infestation).

We could also be lastly reaching a tip level, the place over 50% of our drone pool comes from resistant colonies.

We’ve been approached by our good friend Ray Olivarez, who (after seeing the standard of our hives in almonds) requested whether or not he might promote manufacturing queens from our inventory. He agreed to offer us a big remoted mating yard, which we might load with our personal drone mom hives (permitting us for the primary time to take action solely with resistant colonies). It is a win-win dream come true, since it could permit us to lastly “repair” the genetics for mite resistance into our inventory. Cross your fingers!

Disclaimer: I’m not working this program to advertise our personal inventory, however quite to exhibit to different industrial queen producers keep a breeding program for resistant bees for their very own or some other chosen inventory, equivalent to Harbo, VSH, POL line, Russian, Champlain Valley, locally-adapted ferals, or some other resistant inventory (apologies if I didn’t embrace somebody’s identify). It’s time for our business to shift to protecting mite-resistant bees!