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Bee size, mites, and pesticides

Many beekeepers are convinced that raising smaller, natural-sized bees is the answer to controlling Varroa mites. According to one theory, smaller bees mature faster—in about 19 days instead of 21. This shorter cycle means there is less time for the offspring of a Varroa mite to mature and mate before the adult honey bee emerges from the capped cell. Since a female mite lays one egg every 30 hours, that would mean mites in small cells produce approximately one less mite per brood cycle.

Let’s assume small cell works

That is still a lot of mites. However, today I want to assume that small bees are so successful at controlling Varroa mites that they can be successfully-raised treatment free. If that is true, why are some beekeepers so much more successful at it than others?

I had been pondering this while reading Pollinator Protection: A Bee & Pesticide Handbook (Johansen & Mayer). The text explains that most bee poisoning results from the chance adherence of insecticide residues onto the bee’s body. Then the authors state, “Body size appears to have a direct effect on the susceptibility of bees to insecticides. As a general rule, larger bees are more tolerant of insecticides than are smaller bees. Smaller bees have a higher surface-to-volume ratio and are more susceptible.”

Surface area-to-volume ratio

The surface area-to-volume ratio of similar-shaped objects changes with the overall size. Given a constant shape, the surface area-to-volume ratio will decrease as the shape gets bigger, and increase as the shape gets smaller. That means that a smaller bee has a lot more surface area to pick up a poison compared to its overall body size.

In this case, the authors compared leafcutting bees, alkali bees, honey bees, and bumble bees and they actually measured the surface area-to-volume ratios. Sure enough, leafcutting bees are more susceptible than alkali bees which are more susceptible than honey bees which are more susceptible than bumble bees in a field of treated blooms. As the authors say, “Smaller insects require less chemical to kill them.”

Are small honey bees more susceptible?

This study did not compare small honey bees with large ones, but it begs the question: Are small honey bees more susceptible to insecticides than larger ones? If so, then perhaps small cell bees living in areas with few pesticides do better than small cell bees in areas with lots of pesticides. Maybe it answers the question of why some beekeepers are more successful with small cell than others. Factors other than Varroa mites need to be considered.

I am not drawing any conclusions here—not a single one—I’m only posing some questions. But you can’t take one factor, for example small cell size, and say it is better or worse for bees without examining all possible ramifications. Surely you can argue that bees evolved over millions of years with a smaller cell size, but you could also argue that bees did not evolve along with commercial pesticides. So maybe the larger size helps?

So with no other agenda, I simply pass this query on to you, so that in the wee hours of a cold winter’s night, you have something to ponder.

Rusty
HoneyBeeSuite

Comments

Craig
Reply

As I recall, larger bees were developed because beeks thought they would carry more nectar and pollen.

The people who have regressed their bees tend to think that the larger bees are shorter lived and maybe make fewer foraging trips, so the amount of food and water the bees bring in is pretty much the same.

I’d guess that larger bees will eat more and that it would take fewer bees to cover the brood nest, with smaller cells, so smaller bees might winter better?

As for pesticides… I’d suspect you’re correct about the area/mass thing. But I’m also thinking they might be more susceptible for another reason… Smaller cells would use more wax per frame. Researchers have found that most comb has at least SOME chemical contamination in the wax.

Seems reasonable that more wax would mean more chemical contamination in the hive, if everything else is equal.

I’ve been thinking that part of CCD might be a buildup of these things in the hive, with the bees trapped inside with it all winter. Like setting off bug bombs in your house and shutting yourself in with them.

If a human family did this and they were perfectly healthy, there might be no ill effects. But if some of the family was already sick, very old, very young or just more sensitive to the chemicals… that could be another story.

I don’t have any answers. Just thought I’d add to the confusion a bit. 😀

Dave
Reply

This is something good thing to think about for sure .

I wonder how much of a factor upsetting the macro biology of the hive plays a role in the success of small cell or for that matter large cell period.

It is logical to me that, just like humans overuse or misuse of antibiotics causing us issues, that any sort of treatment, soft or hard chemicals, runs the risk of upsetting the balance required for a sustainable colony.

Another aspect to think about.

Bruce
Reply

I think you have presented one plausible explanation for the varying success rate of small cell beekeepers. The greater proportional surface area of smaller bees may also intensify the detrimental effects of varroa treatments (fluvalinate, coumaphos, the acids…) and the exposure to accumulated hive toxins (agrochemical, domestic, treatments). Insecticidal exposure is usually initially sublethal with the greater danger being exposure to accumulated hive toxins. If true this theory would be applicable to the smaller apis cerana and the africanized bee (not the larger European Dark bee).

Rusty
Reply

Bruce,

The book I mentioned does theorize that “insecticides would be more toxic to Apis cerana and Apis florea and less toxic to Apis dorsata.” Unfortunately, they did not test for it.

alia
Reply

The surface area to volume is a good point when looking at individual bees, but what about the whole hive? If, say, 100 bees out of a hive forage on some pesticide treated plants and come back to the hive (assuming it’s not acutely toxic and doesn’t kill them immediately), will the hive have less pesticide if the 100 bees are smaller and have less surface area for the pesticide to cling to?

Pedro
Reply

Hi Craig,

Smaller animals with higher surface area-to-volume ratio normally have faster metabolisms and shorter life span. They need to spend more energy just to keep going than larger ones. So, one could argue that larger bees overwinter better and not worse as for the same colony total weight there will be less number of bigger bees that consume less energy per capita. So they will be able to keep warm and survive using less resources than a comparable colony of the same total weight but with more number of smaller bees.

So I would imagine larger bees actually eat less!

One could also make arguments as for the longevity of the workers and of the queen. I would imagine in colonies with larger bees the individuals also live longer.

It would be nice to see all this tested scientifically, if it hasn’t been yet.

Just thought I would send the confusion back to you. 😉

Thanks,

Pedro

Craig
Reply

Hmmm….

I haven’t heard anything about smaller bees being shorter lived than larger ones.

But argument is good. Mostly because the truth often resides somewhere in the middle.

Sometimes just because it’s fun to start one, then sit back and watch the fun. 🙂

Pedro
Reply

Hi! Argument is indeed a good thing.

I am on my reasoning extrapolating from data on animals of different sizes, but of their natural sizes. There are two (out of many more, I’m sure) possible flaws with my argument: larger bees, by being larger than evolution selected them to be could have other problems leading to shorter life-span or even greater metabolism, lets, for argument sake, imagine a metabolic disease of some sort; and, second, bees are so called cold-blooded animals, and I totally confess I have no idea if the general rule of decreasing surface to volume ratio – decreasing metabolism – increasing life span found for mammals and birds as been found to exist in insects.

Scientifically designed experiments would be a great way to find out.

Thanks for engaging!

Pedro

Craig
Reply

Pedro,

Actually, the point I was wondering about is this:

While you are correct that, as a rule of thumb, smaller critters have higher metabolic rates (at least as best I can recall), I’m not sure this applies within a given species.

I’m 5′ 10″. My son is 6′ 4″. I promise, he eats more than I do. 🙂

I’m thinking that there won’t be much difference in the metabolic rates of a large bee and a small bee, if both are Apis mellifera ligustica or the like.

It might hold true if you’re comparing an eagle to a bluejay but would it also hold true for two eagles of different sizes?

Pedro

Hi,

Thanks for your reply. I hope Rusty doesn’t mind this discussion going on!

It’s a good question you ask so I did a quick look. I found this study from 2013:

http://jeb.biologists.org/content/217/4/536.long

“Intraspecific variation in flight metabolic rate in the bumblebee Bombus impatiens: repeatability and functional determinants in workers and drones.”

Again a quick look through the abstract and I found this interesting sentence:

«Moreover, differences between workers and drones were as predicted from these functional associations, where drones had larger wings for their size, lower wingbeat frequency and lower flight metabolic rate.»

So it seems they indeed found a relation between size differences within one species and their metabolic rate. But, true, differences between 2 distinct casts within one species. What about differences within one cast? I read the introduction and it cites different studies that seem to indicate there is indeed a relation between intraspecific variation in body size and metabolism, with the later declining as size increases.

As I wrote before, I would be great to see a study of total colony resources consumption and its variation (if any) with body size, once controlled for total colony weight. And longevity!

So, although I would agree this is not a definitive answer to our questions it does seem to hint in the direction of bigger bees having lower metabolism. I’m not sure if you agree?

Again, thank you for engaging.

Best regards,

Pedro

WILLIAM H GATHERCOLE AND NORAH G

Pedro is merely sweeping the internet and cherry-picking those articles that suit the bee conspiracy purpose. Any 10-year-old student can do that for a grade school project. If some anti-pesticide bee conspiracy activists and bee-keepers were not so scientifically illiterate, they would know that scientific research shows that, as reported through EPA’s and Health Canada’s vast toxicology database, no harm will occur to bees with pest control products. Bee deaths are the fault of bee-keepers and their mis-management practices. Bee-keepers are responsible, and not pest control products. In their usual method of arriving at scientifically illiterate conclusions, the anti-pesticide bee conspiracy activists and bee-keepers have somehow concocted the imaginary danger in order to deflect attention from the real problems. They do so by trolling the internet and cherry-picking the MOST NEGATIVE-SOUNDING articles. Of course, the s-called bee crisis is a myth ! Anti-pesticide activists and bee-keepers are the least qualified to provide any advice on this issue. If we had less conventional neonicotinoid use in the environment, we would still have bee colony collapse disorder, because many bee-keepers are not competent to manage their hives. PROHIBITION WILL NOT SAVE BEES. http://tinyurl.com/pxqzh6m Bee conspiracy activists RIDICULOUSLY ASSUME that insecticides are somehow causing bee losses UNLESS IT CAN BE PROVEN THAT THEY DO NOT. Bee conspiracy activists PRETEND THERE IS A BEE CRISIS.

Rusty

This does not make sense. You say “no harm will occur to bees with pest control products.” But insecticides are designed to kill insects and bees are insects. If insecticides don’t kill insects, why do we use them and why would you defend them? Essentially, you are saying pesticides are useless. If they are useless, why do you advocate their continued use?

Gus
Reply

Rusty, as I understand with regards to Varroa mites is that Varroa tend to lay in larger cells—drone—so larger workers 5.4 mm cell size attracts the mite to lay in those cells thus devastating the worker populations. Where with smaller cell size 4.9 mm—natural sized bees—the mites shy away from them and lay in the drone cells.

The theory on the small cell helping with tracheal mites is that the spiracles (the openings into the trachea) that the bees breathe through are smaller in small, natural sized bees and the mites can’t get in.

As far as insecticide tolerance, I feel poison is poison and will kill anything.

Rusty
Reply

Gus,

Varroa mites prefer drone cells because drones take longer to emerge. This allows more mites to reach maturity and mate. Mites prefer the drones of both small and large honey bees because, in both cases, the drones take longer to mature than the workers. That is one reason drone-trapping is so successful as a mite control measure no matter how big your bees are. It is believed the mites find the drone cells through pheromones, not by assessing the size of the cell.

I haven’t heard the theory about spiracle size, but I do know that tracheal mites have become pretty much a non-issue, especially in North America. Pockets of it still exist, but many places report that is no longer a major threat. The theory I’ve heard is that many of the treatments for Varroa are having an effect on the viability of tracheal mites.

Find a copy of Pollinator Protection; you’ll find that these poisons don’t necessarily kill everything and that tolerance is important to the survival of many species, including bee species.

Peter
Reply

I enjoy your web site and wish you well and continued success.

I also think a slight correction is needed. The following statement is not accurate. “That means that a smaller bee has a lot more surface area to pick up a poison compared to its overall body size. ” The surface-area-to-volume factor does not affect the amount of poison “picked up”; a smaller bee should pick up smaller quantities of poison. The smaller bee has a smaller volume relative to surface. It is the poison to body volume (mass?) ratio. Smaller bees have less relative mass to dilute the poison.

Regards Peter

Rusty
Reply

Peter,

I stand by my statement, although the wording could be improved. Obviously, a smaller bee has a smaller surface area than a large bee, but it is the surface area compared to the bee’s volume that affects how well or how efficiently the bee can handle or detoxify that amount of poison. The best explanation of surface area to volume ratio I ever saw was in my eighth-grade geometry book. Maybe I need to find one of those to improve my explanation.

Dana
Reply

Well, okay, let’s assume the raising of larger bees helps pesticide resistance for the reasons already stated. Following that fork in the trail would be helpful.

We still need to keep in mind the real subject of the conversation here is about pesticide usage. The long term preventative solution is going down the parallel path of using fewer pesticides.

WILLIAM H GATHERCOLE AND NORAH G
Reply

NORAHG RESPONDS AGAINST BEE-KEEPERS WHO USE DEADLY PRODUCTS

Dana should have also mentioned the less savoury strategies used by bee-keepers. There are a growing number of reports that bee-keepers all over North America are violating federal law by using illegal, unregistered, deadly, and cancer-causing pest control products. Recently, in Alberta, bee-keepers were fined for using these unregistered pest control products to combat mite infestations, resulting hefty fines from Health Canada. Bee-keepers violate federal law by using products like amitraz, which is known to cause cancer, and is known to kill people. In 2006, the United States Environmental Protection Agency ( USEPA ) classified amitraz as a group C, a possible human carcinogen. Furthermore, exposure of men to greater amounts of amitraz can lead to death due to respiratory failure, mainly after oral uptake or inhalation. In Turkey during 1989, 41 cases of deadly amitraz intoxications were detected. Other frequently occurring symptoms after massive amitraz intoxication are bradycardia, depression, hyperglycemia, hypothermia, loss of consciousness, miosis, respiratory depression, and vomiting. In other words, bee-keepers are illegally using products that are known to cause cancer, and are known to kill people. It has been concluded that bee-keepers are producing potentially dangerous honey. And yet, these same bee-keepers complain about neonicotinoid insecticides, which, in fact, do not cause cancer, are scientifically-safe, and cause no harm. If bee-keepers are lying and cheating by using illegal products, then, are they also lying and cheating with their public statements about bee deaths and neonicotinoid insecticides ?!?! If we had less conventional neonicotinoid use in the environment, we would still have bee colony collapse disorder, because many bee-keepers are not competent to manage their hives. PROHIBITION WILL NOT SAVE BEES. http://tinyurl.com/pxqzh6m For more information regarding BEE-KEEPERS & ILLEGAL, UNREGISTERED, DEADLY & CANCER-CAUSING PRODUCTS, go to The Pesticide Truths Web-Site … http://wp.me/p1jq40-70c http://wp.me/P1jq40-2BA NORAHG is the National Organization Responding Against HUJE that seek to destroy the Green space and other industries. WILLIAM H GATHERCOLE AND NORAH G Get the latest details at http://pesticidetruths.com/ http://pesticidetruths.com/toc/ http://wp.me/P1jq40-2rr https://www.facebook.com/norah.gfon

Rusty
Reply

Amitraz (Apivar) is legal in all 50 states.

Craig
Reply

So nicotine DOESN’T cause cancer?

Can’t wait to inform every doctor in the world that they’ve been wrong about that for the past 30 years!

Craig
Reply

Pedro,

Rusty hasn’t told us to shut up (yet), so I’m working on the assumption that she doesn’t mind. 🙂

Although we DID run out of room to nest comments, it seems.

That study is a bit over my head but it seems to be talking about the metabolic rate during flight. It appears to be saying that larger bees, with larger wings, fly more efficiently.

Further down, though, it states “Metabolic rate increased significantly with body mass, and drones had lower metabolic rate than workers…”

From what I can gather, the article seems to indicate that larger bees have a higher metabolism but are more efficient in flight.

So, while flying, the larger bee has the advantage… but while at rest or walking, the smaller bee comes out ahead?

Since bees spend roughly 3 weeks of their lives working in the hive and 3 weeks working as foragers and if smaller bees are more efficient in the hive but larger bees are more efficient while flying… it seems the differences would probably be negligible? For Summer bees, I’m thinking it would all just about average out, which would mean that you and I were both wrong.

However, since winter bees generate heat by unhooking their wings and flexing their wing muscles, that might mean that the larger bees would have the advantage, in the winter cluster. If that’s the case, it would tip the scales in your favor, I’d say. 🙂

Pedro
Reply

Hi Craig,

This has been an engaging discussion and if anything it shows that things sometimes aren’t as clear cut as one might imagine. I would say the jury is still out on this one. Nothing like a good scientific experiment to sort things out!

I would love to see one done to answer this question.

I hope we will meet again in another nice discussion in the near future. Nice discussion and internet can be a very rare pairing indeed, so, much appreciated, thank you. And thanks Rusty for making it possible!

All the best,

Pedro

Anna
Reply

Regarding small cell: I use it simply because anything larger than nature intended doesn’t tend to do as well as the “normal” or “natural” sized version. If you can’t tell, I work in health care.

Rusty
Reply

Anna,

I would think the same applies to small cell. What not use natural cell size instead of forcing it one way or the other?

Anna
Reply

I guess it depends on what you consider to be “natural” cell size. Using Michael Bush’s site, small cell would be considered natural. What cell diameter are you thinking of as being natural?

Rusty
Reply

Anna,

By “natural” I mean you let the bees decide on the size instead of deciding for them. Whenever you use foundation, you are deciding for them. I’ve heard Michael Bush say there is more variability in natural comb, that the cell sizes are not so regimented. The bees will build a little bigger or a little smaller according to their immediate needs. In any case, I don’t consider small cell “natural” simply because foundation is not natural. Only what the bees themselves decide to build is natural.

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