Contents
A Deeper Glance into our Information. 1
Was once Robbing Concerned with Mite Immigration?. 6
Phase 5
Randy Oliver
ScientificBeekeeping.com
First revealed in ABJ June 2023
There used to be obviously drifting of bees from the collapsing colonies, with them possibly wearing hitchhiking mites. However averages and statistics aren’t just about as informative as taking a look on the information from each and every particular person hive.
A Deeper Glance into Our Information
Query: Is mite immigration secure or episodic?
Let’s have a look at the semi-weekly mite drop counts over the years for the Receiver hives, once more damaged down via distance from the Donors (Determine 1).
Fig. 1. Mite immigration adopted a remarkably clean and constant curve, peaking in October (coinciding no longer simplest with Donors collapsing, but additionally when their mite ranges peaked). The coloured columns point out the reasonable semi-weekly per-hive mite drop for each and every distance team of Receiver hives; the black columns are the overall collection of drifted bee tags recovered on each and every date. The low preliminary fee of tag restoration is most likely an artifact folks no longer starting our tagging of younger bees till 17 September, from which we wouldn’t be expecting any flight or go with the flow till a minimum of a number of days later.
The tall pink columns point out upper mite drops within the unmarried Receiver at 15 toes, however unusually, there wasn’t a lot distinction in reasonable mite drops between the 60- and 500-foot teams of Receivers.
Additionally observe the considerable lower in mite immigration starting on 25 October. It didn’t seem to be any exchange within the climate (Determine 2).
Fig. 2. Days have been heat and sunny during the length of this find out about.
Something that had modified used to be that the high-mite Donors had in large part collapsed via that point, so the volume of obvious mite immigration did seem to coincide with the 2 episodes of Donor colonies collapsing.
Query: How heavily did mite immigration correlate with the drifting of tagged bees?
The black columns in Determine 1 point out that there used to be steadily a correlation between the drifting of tagged bees and mite immigration. However since we have been deliberately tagging bees right through the method of each and every Donor colony collapsing, it’s no longer unexpected that there could be a correlation. So let’s smash the information down via hive (Determine 3). (Reminder on hive numbering: D1 approach Donor #1; R1 approach Receiver #1).
Fig. 3. For some Receivers, the correlation between mite drop and incoming drifted tagged bees used to be sturdy; for others it used to be susceptible. So it’s tough to attract conclusions (particularly because the probability of a drifted bee wearing a number of mites is most likely random). Once more, since we tagged this sort of low proportion of bees in keeping with Donor, it’s no longer transparent whether or not the immigrated mites got here basically from the Donors, or from unknown colonies (controlled or feral) locally.
A very powerful qualifier so far as making an allowance for this as a longitudinal find out about: This find out about used to be set as much as decide whether or not the relatively-sudden will increase in mite infestation charges in our colonies used to be because of mite immigration, and from colonies at what distance. For this reason, we deliberately tagged bees within the Donor hives after we noticed that their mite ranges have been peaking they usually have been present process the method of cave in. Thus the entire correlation between tagged bee restoration and mite immigration is most likely a minimum of in part an artifact of the timing of after we tagged bees. So even though the mite drop counts qualify as a longitudinal find out about, our tag restoration information are skewed via our asymmetric tagging of bees week via week. Thus the emigration of our tagged bees would possibly not mirror the true timing and charges of emigration of the collection of untagged mite-carrying bees that drifted to the Receivers (and their related switch of mites).
Interpretation: It’s no longer transparent whether or not the drifting of tagged bees (and mites) used to be the results of easy diffusion of bees drifting in each instructions (Donor-to-Receiver and Receiver-to-Donor), or relatively because of there being an higher exodus of bees from colonies as they collapsed. However, in spite of the extensive hive-to-hive diversifications within the overall drifted tag recoveries and overall obvious mite immigration over the process all the find out about, it will lend a hand to damage that information down additional.
Differently of taking a look at our information is to make use of a scattergram (beginning on 1 October after we began to get better tags). This permits us to decide, for each and every hive take a look at, the level of correlation between the collection of drifted tags, relative to the corresponding mite drop depend for that particular period of time, impartial of calendar date (Determine 4).
Fig. 4. Considered this fashion, there used to be a remarkably sturdy correlation between the collection of drifted tags from the Donor hives, relative to the collection of interestingly immigrated mites at the stickyboards (the counts aren’t ordered via date).
Since we don’t know needless to say the supply colonies for all of the immigrated mites (and because the tagged bees represented this sort of small percentage of the Donor hive staff), it’s unattainable to attract company conclusions from this chart ― the correlation would possibly smartly were even upper if there were no different colonies inside flight vary, or if we had tagged a bigger percentage of the employees within the Donor hives.
Interpretation: Even supposing tagged bee go with the flow and mite immigration each coincided with the collapses of the Donor colonies, we didn’t start tagging bees early sufficient, or persistently sufficient, to inform whether or not the method of cave in led to an exodus of drifting mite-ridden bees (Mite Bombs), or whether or not it used to be merely because of commonplace drifting. One would wish to repeat the find out about ― tagging the similar collection of bees each and every week — to determine. Finally, it no doubt seems that there used to be a robust correlation between the drifting of tagged bees and mite immigration. That reality means that the immigrated mites did a minimum of in large part come from the Donors, relatively than from unknown hives, since the ones unknown colonies would have had to were losing mites at the similar days that our Donor hives have been dispersing drifting tagged bees.
We will be able to take even a more in-depth have a look at our information, which I’ve damaged it down in two charts — one for the shut Receivers, the opposite for the ones within the 500-foot team (Figures 5 & 6). Understand that some Donors collapsed in mid-to-late September, the remaining in mid-to-late October, which is mirrored within the stickyboard counts (on this case ordered via date).
Fig. 5. For the Receivers positioned close to the Donors, it sounds as if that some have been “mite magnets” (pink and pink), while others suffered from little mite immigration.
Fig. 6. Very similar to the shut Receivers, a few of these more-distant Receivers persistently dropped extra mites than others, impartial in their distance from the Donors.
Interpretation: What surprises me is the consistency of the obvious mite immigration into one of the vital hives, while in others it might move up and down (as I’d be expecting from random go with the flow). And so far as my nagging query about whether or not the high-count receivers have been producing their very own mites, check out the sky-high stickyboard counts of R5 and R7 (pink columns), which I inspected on 17 October, and showed that they have been necessarily mite loose.
Word that via early November, the stickyboard counts dropped to very low numbers, in spite of there nonetheless being quite a lot of bee flight because of the elements closing heat.
Now we have just one final query to move:
Was once Robbing Concerned with Mite Immigration?
Query: Did mite immigration Correlate with Robbing at My Location?
Previous on this collection I identified that even though wholesome colonies would possibly rob mite-infested colonies in the event that they comprise ripening nectar on the time in their cave in, that didn’t occur right here. We had positioned scales beneath each our Donor and Receiver hives with a purpose to see whether or not the Donors misplaced weight right through cave in (which might point out that they have been being robbed), or whether or not the Receivers won weight right through our dearth (indicating that that they had robbed a collapsing colony) (Figures 7-9).
Fig. 7. An instance of what I appeared for ― a Donor shedding pounds on the similar time {that a} Receiver used to be gaining it. I’ve aligned those two snips via date, to turn D8 shedding pounds whilst R4 won it. However taking a look again to Determine 5, one can see that R4 exhibited minimum mite immigration right through that period of time. So despite the fact that it used to be robbing, it wasn’t bringing again mites.
Fig. 8. A screenshot of scale information for the Donors [[1]].The one surprising weight losses that we noticed have been for Donor D6 and D8 (no longer proven on this chart) ― the remainder of the Donors confirmed no indication of having robbed right through their cave in. However the bulk of the ones weight discounts would possibly smartly have merely represented the frame mass of the employees that deserted the hive (the bees masking 8 combs weigh kind of 4 kilos).
Fig. 9. A screenshot of standard scale information for the Receivers, with weight positive factors via R4 and R7.
Dialogue on Robbing
In my arid local weather ― during which there’s no considerable nectar float in overdue summer season — we noticed no indication of weight reduction because of robbing going down because the Donors collapsed, nor any considerable weight positive factors to indicate that the Receivers have been robbing different colonies.
This isn’t to mention that mite immigration can’t even be related to robbing in spaces during which robbing does happen as colonies cave in, reminiscent of the place nectar is ripening within the hive at time of cave in.
Even in the ones spaces, precise box information indicating that robbing is extra of an element than is drifting, is (so far) in large part circumstantial. Even supposing it “is sensible” that mites would show off a conduct to hop on robbing bees for a journey to a brand new host colony, something that I’ve discovered through the years is that simply because one thing “is sensible” to the human thoughts, that doesn’t essentially imply that it in truth takes position with honey bees. So let’s check out the proof.
Ever since Del Piccolo [[2]] reported that mites “most well-liked” nurse bees over pollen foragers, interestingly because of variations of their cuticular hydrocarbons, it’s been lovely smartly established that there’s get advantages for a mite to discover a nurse bee to feed upon (reviewed via Xie [[3]]). My very own checking out [[4]] showed that non-flying (possibly younger) staff in most cases show off upper infestation charges than do flying staff sampled from the similar comb.
However Cervo [[5]], came upon (by means of GC-MS) that because the varroa infestation fee of a colony higher, the adaptation in smell between nurse bees and foragers disappeared, as did the desire of mites for nurses over foragers (as made up our minds via host-preference exams in petri dishes). That discovering would recommend that the mite infestation fee of foragers, relative to that of the nurse bees, would building up because the infestation fee grew — thus leading to a bigger collection of mites at the older staff drifting from highly-infested colonies.
However what occurs in relation to foragers from low-mite colonies robbing out high-mite colonies? Peck and Seeley [[6]] noticed a circumstantial connection, main us to wonder if the mites in demise colonies acknowledge the robbers as being “international,” after which hop onto them with a purpose to catch a journey out in their sinking send (this could make “overall sense” since it might support in horizontal transmission). However alas, Cervo’s findings don’t enhance that speculation — they discovered that mites “didn’t display any desire between homocolonial and heterocolonial foragers at any mite abundance of the colony.”
And in possibly the one find out about during which mite ranges on returning foragers have been quantified, DeGrandi-Hoffman [[7]] discovered that:
We didn’t locate excessive proportions of [foragers with mites] right through any sampling length as could be anticipated if foragers have been robbing closely infested collapsing colonies. Even though will increase in mite numbers because of robbing most likely happen, our information recommend different conceivable explanations for sudden enlargement in mite populations. [Foragers with mites] comprised at maximum 2–3 % of all of the foragers we captured in a sampling period.
DeGrandi-Hoffman’s find out about happened in Tucson, Arizona, the place there are late-season nectar flows [[8]], so it’s no longer transparent whether or not robbing used to be going down. I beg additional analysis to discover the true quantity of mite switch that takes position because of robbing!
Box Learn about Wrap Up
The elements in the end grew to become chilly in overdue November (Determine 10).
Fig. 10. Ambient temperatures remained excessive smartly into November
This gave me a possibility to substantiate that our Receivers have been nonetheless mite loose. We took our final two stickyboard counts on 26 and 30 November, right through the meantime during which it in the end were given chilly (and wet) sufficient to stop bee flight (and thus mite immigration because of robbing or drifting bees). The stickyboard counts at the 26th have been 9,,6,1,2,8,5,2,4,14,7,10,2. Through the 30th that they had dropped to 0,1,0,0,3,0,0,0,0,0,1,0. Once more, sturdy proof that the Receivers weren’t generating their very own mites.
I additionally checked the Donors—all have been devoid of bees, rather then D4, D5, D7, and D8, which had tiny clusters slightly below the lid. And I simplest noticed a unmarried closing tagged bee (in D8). With that, I wrapped up the find out about.
Evaluation
So what are the take-homes from our find out about?
- I arrange this trial to decide whether or not the late-season building up in mite infestation charges in our hives might be due from the drifting of bees from infested colonies outdoor our apiary. We discovered that there can also be considerable bee go with the flow into hives a ½ mile remote, and a few go with the flow to colonies a complete mile away. Thus now we have laborious proof to enhance simply how necessary it’s to inspire your neighbors to regulate varroa of their colonies!
- We counted just about 3000 apparently-immigrated mites from our Receiver hives ― a median of 245 mites in keeping with hive. The ones immigrated mites weren’t frivolously disbursed, however even within the hives receiving probably the most mites, the ones immigrated mites would simplest have higher the infestation charges of the ones colonies via about 1% (3 mites in keeping with part cup of bees). So even with 9 colonies collapsing on this apiary, shall we rarely blame any massive will increase in mite wash counts within the surrounding colonies only upon mite immigration from different hives.
- Different analysis has proven {that a} considerable proportion of staff would possibly go with the flow between hives in closely-spaced apiaries. On this trial we all know from recovered tags that a minimum of 4% of the bees we tagged drifted into the 21 hives that we monitored, however since there have been additionally unmonitored hives within the space, that 4% determine is obviously an underestimate of the whole quantity of out-drifting that in truth happened. Based totally upon the sturdy correlation between tag restoration and mite drop, there may be explanation why to suspect that our sporadic tagging of bees (in an try to coincide with cave in), most likely underestimated the real level of drifting of mite-infested bees that in truth passed off.
- There used to be way more go with the flow to remote colonies than could be anticipated accidentally. This discovering is totally opposite to “not unusual sense,” and presentations how little we know the way and why bees go with the flow. It additionally brings into query suggestions in regards to the spacing of hives in an apiary to cut back drifting.
- There used to be a persistently massive variation in mite immigration between hives that have been side-by-side at more than a few distances from the Donors, indicating that some colonies seem to be extra (or much less) sexy to (or prepared to just accept) drifting bees than others (even though the volume of mite immigration didn’t essentially correlate with the volume of entered drifted tagged bees).
- We noticed that probably the most intense mite immigration into the Receivers happened when the Donor colonies have been at their very best infestation charges (and likewise collapsing). It’s no longer transparent whether or not mite immigration used to be basically the results of infested staff leaving behind colonies and looking for different hives as they cave in (the “Mite Bomb” speculation), or merely because of the continuous mite diffusion related to “commonplace” bidirectional bee drifting.
- In the environment, with no considerable nectar float going on right through the find out about, the collapsing colonies didn’t get straight away robbed, and there used to be no correlation between weight acquire (indicating robbing) and mite immigration.
Replace August 2023: I introduced quite a few colonies with very excessive mite counts (30-70 mites in keeping with part cup of bees) to my house backyard with a purpose to harvest are living mites from them for my research. To my dismay, quite a few them were given robbed out as their populations have been collapsing. Since I used to be examining the colonies frequently, I used to be in a position to heavily watch the method of cave in after which robbing.
As soon as a colony reaches the DWV “tip level” (mite counts round 50 or above), its quantity of brood begins to lower, and the employee inhabitants starts to cave in impulsively (via as much as two frames of bees in keeping with day). And as soon as the cluster can slightly duvet 3 frames, in a crowded backyard, robbing drive can change into an excessive amount of (remoted colonies with just a handful of staff are in a position to shield themselves in my space). As soon as robbing begins, it explodes! No noticeable robbing within the morning, however inside an hour of when it starts, the hive is mobbed via robbers. Even supposing the colony’s staff valiantly try to repel the robbers, they get beaten, and a double-deep hive is in most cases “wiped clean out” of honey inside an afternoon or two.
The Aftermath
Once I check out the hive straight away after robbing ceases, the combs are devoid of honey, and far of the brood has disappeared. There are lifeless bees at the backside board, however I have no idea whether or not they have been defenders or robbers. However there may be steadily a closing reformed cluster of are living, hungry bees – they don’t essentially die or go with the flow away. That cluster would possibly constitute a considerable percentage of the employees provide previous to the initiation of robbing.
I used to be curious this morning once I inspected a colony that were robbed out over the last two days, whether or not the rest bees had given up their mites to the robbers. Up to I hated to sacrifice the ones deficient survivors, I took a pattern of a part cup of them and washed the mites off them.
There have been too many to depend in a pile, so I divided them up and counted them two times. There have been 117 mites on the ones roughly 315 bees! It sounds as if that their mites had no longer hopped off at the robbers to any extent, since my mite wash depend from the similar colony a couple of days previous were simplest 44.
Subsequent Month
My function for enterprise this find out about used to be to reply to my query “Are the seemingly-rapid spikes in our mite wash counts in overdue summer season basically because of the immigration of mites from different hives?” That explanatory speculation is very sexy, because it places the blame on somebody else, relatively than on one’s personal insufficient varroa control. However I’m no longer positive that it holds water. Subsequent month we’ll have a look at further laborious information, and run some simulations.
Acknowledgements
Thank you once more to my helpers Brion and Alice Dunbar, Sandy Honigsberg, Anna Mudd, and Brooke Molina. And to Dr. David Peck for reviewing my information.
Citations and Notes
[1] Because of unfamiliarity with information preservation for the dimensions hives, we misplaced all our uncooked information after we got rid of the batteries from the scales on the finish of the trial. Fortunately, I were following the burden information right through the process the trial, and had taken a couple of screenshots. I absolutely anticipated to look proof of robbing correlating with mite immigration, however didn’t.
[2] Del Piccolo, F, et al (2010) Number of Apis mellifera staff via the parasitic mite Varroa destructor the use of host cuticular hydrocarbons. Parasitology 137(6): 967-973.
[3] Xie, X, Z Huang, & Z Zeng (2016). Why do Varroa mites favor nurse bees? Medical Experiences 6(1): 1-6.
[4] https://scientificbeekeeping.com/re-evaluating-varroa-monitoring-part-4/
[5] Cervo, R, et al (2014). Top Varroa mite abundance influences chemical profiles of employee bees and mite–host personal tastes. Magazine of Experimental Biology 217(17): 2998-3001.
[6] Peck, D & T Seeley (2019). Mite bombs or robber lures? The jobs of drifting and robbing in Varroa destructor transmission from collapsing honey bee colonies to their neighbors. PloS one, 14(6), e0218392.
[7] DeGrandi-Hoffman, G, et al (2016) Inhabitants enlargement of Varroa destructor (Acari: Varroidae) in honey bee colonies is suffering from the collection of foragers with mites. Experimental and Implemented Acarology 69(1): 21-34.
[8] Nightingale, J, et al (2008) Assessing honey bee equilibrium vary and forage provide the use of satelite-derived phenology. In IGARSS 2008-2008 IEEE World Geoscience and Far flung Sensing Symposium (Vol. 3, pp. III-763). IEEE.