Why releasing Mason Bees on your property is a bad idea
In the last few weeks, I have been asked by three people questions about buying and releasing Mason Bees onto their property, so I thought I would sit down and write-up why I think that is a bad idea. All of the sources listed are free, so anyone interested can read further.
https://docs.google.com/document/d/1QqgZJmAfpnqb28wHjd8XR5yXtiWu0QM_kCX3fRfyJ84/edit?usp=sharing
Posted by
neylon,
April 18, 2022 02:24 AM
neylon,
April 18, 2022 02:24 AM
Comments
Thank you for taking the time to share your expertise and references on this topic.
This post is interesting, although I'm not aware that the release of O. cornifrons and M. rotundata would be expected to have a very detrimental effect on native species, at least not much beyond the effect already-wild populations already have had. I also think A. mellifera is much more "harmful" although is more widely used, and think it has some qualified uses. I'd also point out that many people who release those mason and leafcutter bees, and also some companies selling them, are doing so in contexts like plant pollination, research, education, etc. And that research can in theory be for general bee conservation (as can research using Apis mellifera). I think it's worth pointing out what species are native vs. non-native and what negative effects they could have (especially for buyers who only want to emphasize native species, although doing so isn't always required), but also that there are qualified uses for releasing mason and leafcutter bees, and to use bee hotels (which are often used together when buying bee cocoons).
Another thing to keep in mind is there are often trade-offs between human benefits and wildlife conservation in matters like this, such as in using apiaries, but it wouldn't be considered feasible for example to avoid or set strict limits on how many Apis colonies individuals or companies can use. Although on that, I have heard of recommendations which may also be enforced in some areas that set a maximum number of honeybee colonies per unit of land that encompasses an entire town, city, or county. What that also shows is that recommendations or requirements for the use of apiaries, along with released mason or leafcutter bees in principle, can also be done via general policies which don't entirely recommend against or ban the practices. So overall, I think there are pros and cons to know about and consider for releasing bees, but that there are qualified uses and it may not be very (newly) harmful.
You could consider raising the question as a discussion topic in the bee_monitoring email listserv. But if rephrasing your view there, be aware that a representative from the company Crown Bees is a member and will probably be one of the people who reply. I've bought a bee hotel from Crown Bees and do think their products like the bee hotels are well-designed and based on research and conservation. I find the idea of raising cocoons interesting for research or education purposes and considered buying them from Crown Bees, although haven't so far. When I first read about cocoons, I also realized cornifrons and rotundata are pretty much the only species sold. It would be interesting if native megachilid species could also be used. Although among megachilids, the males of Anthidium manicatum and oblongatum (which are non-native in the US) guard floral resources and can kill other bees, so Anthidium in particular probably shouldn't ever be released. Lastly, you are also right that at least some gardeners buying corniforns or rotundata cocoons don't realize that they aren't native, which having more public information or education on this topic may help inform.
I do appreciate you taking the time to read it and give counterpoints. But if I may respond to your points:
While I do agree that Apis are much more detrimental to native bee health than releasing a few Osmia would ever be, but there is already quite a few people who have written much on the conservation effects of Apis, this is specifically covering a different problem which is largely not discussed as it is a much smaller issue.
First, to make a semantic correction: I'm not raising a question, I'm making a statement; the harmful effects of these added species are established with added disease, resource and mating competion. This is more than whether it is aggressive or not (which it is not).
However I would recommend reading some of the papers that I refer to in the article. One discusses the decline of 6 species of native Osmia after the introduction of O cornifrons and taurus (taurus is often an accidental addition due to its similarity to cornifrons). Another discusses the movement of harmful fungi to North America due to movement of cornifrons. Also note the other papers that discuss general disease from non-native insects (ie Apis, B impatiens).
Also as noted that even when trying to order native species (ie Osmia lignaria), many sellers (from what I've heard including CrownBees) do not differentiate between the eastern Subspecies (O lignaria lignaria) and the western Subspecies (O lignaria propinqua), so now you not only have the problems of higher risk of disease from domestically raised insects, and artificially added resource competition, but you would also be adding mating competition into the mix. Which could potentially further reduce the local population.
As to bee hotels, at the moment I'm not against there use. I have heard of several native wild species that have been recorded using them. However, Lecroy (the author of the paper on declining native Osmia) in an interview discussing a paper I have not been able to get ahold of so didn't get into it in my article, mentioned two concerning issues. One, non-native species use those to a much higher degree than native species, meaning that bee hotels may just be assisting in the spread of non-natives. Two, insects that parasitize bee nests were recorded preferring native to non-native nests in hotels, so hotels could be creating a habitat sink. I do have questions though, like is the non-native use because hotels are always set up in urban environments where non-native species thrive anyway? And are the parasites just preferentially choosing the species that they are naturally associated with? So I'm not against them yet, but these questions are concerning. But considering the benefit that many species of birds have had from manmade nest boxes, I'm hesitant to write-off bee boxes too quickly.
On who is buying them. Many places that sell these sell them under the banner of "save the bees" and are being purchased by well meaning people who want to release them in their yards, to those people I strongly encourage them not to. As to the pollination services, yes, at this time non-native species are just about indispensable to crop pollination. But these should be thought of as crutches that we are trying to get off of, not something that we double down on and bring in more. See the paper I referenced on native wild bees for watermelon pollination.
As to Conservation/research/education. I don't see the point of non-natives from a conservation perspective. Research doesn't seem plausible as the behaviors of Apis and the non-native Osmia are quite different from the native species. And I'd much rather educate people about native species rather than two non-natives.
A big one to remember is that humans have been moving species around for centuries, and every time there are detrimental effects. I think we finally hit the point where our government got it through their thick skulls that adding multiflora rose, honeysuckle, Non-native Osmia and Anthophora, ect were all a really bad idea. But even now in my area there is someone releasing European Goldfinches and up north someone released a population of Great Tits (yes that is its name, I'll pause while you finish laughing). So I would rather foment a general feeling of distrust and apprehension from people when considering releasing things that shouldn't be here. People look at one small benefit and don't consider the consequences. I could get into a few potential consequences of the afore-mentioned birds being added, but this is getting long.
Personally, I have a knee-jerk to the government getting involved in anything, and bile comes to my mouth hearing the word "regulation", but the thought that reducing the amount hives inundating the landscape and potentially later reducing sold insects in general would make me very happy.
It occurs to me that explaining the problems with those two birds adds to my points.
To start with, the problem with adding Great Tits (hahaha) are obvious: in their home range (Europe) they have a well recorded history of eating Bombus queens in the early spring. Oh good, let's take one of the focal areas for Bombus affinis and add a predator that would target their gynes.
For European Goldfinch it's much more subtle. Would they displace American Goldfinches? No, they nest at different times of the year. Compete for resources? Largely not, in fact the first time they tried to introduce European Goldfinches failed largely because a preferred food of theirs, Teasel wasn't here. It is now, which comes to the first problem. Teasel is enormously invasive and impossible to get rid of, on two occasions I've informed land managers of a small stand of Teasel that I found and had them out with herbicide to deal with it immediately. Euro Goldfinches eat and spread it.
But the 2nd problem is also interesting and I have to give some history of a different bird to explain it. Prior to the 1940's, there were no House Finches east of about the Rocky Mountains. They were sold in pet stores as "Hollywood Finches" after laws were passed to protect native birds were passed it became illegal to sell those birds so stores like Macy's just released them. Somehow these released pets managed to find food, survive winter, breed, and expand. They hit my area (northern IL) in the mid-70's (side note we had a guy who kept extensive bird lists here in the mid 70's named William Sheppard, he documented the arrival of the House Finch and a major winter finch irruption), and currently cover the united states coast to coast. Unfortunately, these release birds are prone to "red-eye disease" which was a big problem up until recently. While it is still a problem, from what I have seen it doesn't appear to be quite the level it used to be. This wouldn't be so bad if it wasn't for the fact that American Goldfinch, Pine Siskin, Common Redpoll, Evening Grosbeak, Pine Grosbeak have all been documented with that from contact with House Finches and in 2012 the first record of red-eye disease west of the Rockies was recorded.
If another introduced finch is allowed to thrive, that would potentially be another source of diseases for the native species of finches to deal with.
I read all the articles now, and had read some of them earlier. I made the distinction that I'm not referring to introductions or to situations where people buying bees would be causing them. Introductions are well known to have potentially large detrimental effects. What I said is the current practice of releasing M. rotundata and O. cornifrons may not be doing significant harm beyond the harm already caused in their original introductions. I'm also not referring to biocontrol releases. I only have some knowledge of the prevalence or all of the reasons people release these megachilids, although am mostly familiar with what I read on the Crown Bees website. They only sell rotundata and cornifrons, and I'd like to only focus on those species and on the policy of that company. Because they try to incorporate research and conservation into their products and educate customers, so aren't an example of bee washing.
First, looking through some of the articles you linked to (or ones they cited), I see it mentioned that these megachilids are easiest to raise and to use for research, which was implied to have applications beyond those species, as I said. There are also some native megachilids in the US (which I don't think are released), so the distance between them and ones usually used isn't that far. Essentially, these species (and maybe a couple others) are the main or only options currently for releasing bees, at least for customers who don't have previous experience with releasing bees. I also agree that one of the largest possible problems can be pathogen spread. Although, many of these problems also affect Apis mellifera even more, yet it continues to be managed at a much more massive scale and also is among the most competitive and resource depleting species to native bees. The research on pathogens associated with Osmia also seems only partially understood so far, at least in assessing the overall detrimental likelihood caused from current releases alone (not considering the original introduction or practices that would case introductions). I'm also not defending all companies, in case some have less conservation-considering practices. So if any company is known to be causing introductions, I'd at least agree that they should restrict where they ship bees to in order to prevent introductions.
Looking briefly through some of the Crown Bee pages now, they address most of these issues. They talk about practices they use to reduce pathogens in their bees, and educate customers how to harvest cocoons and clean bee hotels in ways that also reduce or prevent pathogens. They also say as I implied that M. rotundata is already established across the country, making the practice of releasing it unlike an introduction (I didn't finish reading about what the situation would be for O. cornifrons, but expect it to be relatively similar). But, this isn't to say that the practice of releasing bees is perfect or could have no downsides. I just think it's more complicated than a suggestion for everyone to refrain from doing entirely it would suggest. I also mentioned there are trade offs, where people also value some of the human benefits (education, research, pollination, etc.). So, I think there are qualified uses.
I do also agree that the research on possible detrimental effects is very important to continue monitoring. And that if a massive detrimental effect at the level of populations were to be expected from people releasing megachilids in the way we're talking about, then at that point the practice may be best to recommend further reducing. It just doesn't seem realistic to expect people would stop the practice entirely. You're also fine to take the view that no one should release bees, it's just that I think there are valid research, education, and/or pollination reasons some do, which would make sense to minimally support as a justified use in my opinion. Also, not that you have to post the topic to the email listserv, but I just meant that if you were to you would probably hear people express some differing opinions. You could also optionally post the link to this page to the forum bee/wasp message "listserv," in case anyone wants to add to the discussion on the current page. Below are some of the Crown Bee pages I mentioned, and you could also search through more pages on their website for further details:
https://crownbees.com/where-our-leafcutter-bees-come-from/
https://crownbees.com/parasites-and-diseases-of-mason-bees/
https://crownbees.com/read-this-before-you-buy-bees/
As to the prevalence and how wide spread they are, we are equipped right here to judge that:
Osmia cornifrons
https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=121508
Osmia taurus
https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=461507
Megachile rotundata
https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=52783
And here you can see that even within the ranges there are empty areas where they possibly haven't been introduced yet. Especially cornifrons as they have a tendency expand slowly.
Regardless though, I can't think of a single introduced species that became a non-issue no matter how long it was here or how widespread it became. Also to point out, the damage did not happen when they were first introduced and were in small confined areas, the damage grew as their ranges expanded, so why would we assume it would be different for Bees? Especially when the initial research suggests otherwise.
Honeysuckle, nightmare shrub that has completely conquered our woodlands. Any woodland it takes over will lack spring flowers blooming. This has been here for a long time and a huge amount of time and effort goes into its removal.
House Finch, disease. See previous comment, been here for decades.
Apis, disease and massive resource competition. Widespread. Been here since the 1600's
Ring-necked Pheasants. Routinely parasitize nests of Greater Prairie Chickens and other game fowl. Contributor to the disappearance of Prairie Chickens in IL. Widespread. Been here since 1900.
Many plants species that are pretty much established that must be constantly controlled.
For research, I still fail to see the practical benefits. Introduced species have a strong inclination towards an urban environment, which would give little information about their native preferences. And the introduced species in discussion here are part of rather small Subgenera in comparison to the large amount of other native Subgenera. Subgenus Osmia in particular, most of the species in that group are non-native, and Native Subgenus Osmia like lignaria readily use hotels and strikes me that it wouldn't be that much harder to study these. Releasing for research still seems like it would have rather limited benefits vs the potential harm.
While yes the potential harm at the moment is just that: potential, and the declines are not fully understood. Considering that in every case an introduced species becoming widespread has always caused great harm, I would rather error on the side of "let's not, and say we did". I don't think it's a good idea to wait to be concerned until we've confirmed whether or not it's a problem, because in that case it's too late.
To Crown Bees. At this point Crown Bees has been a primary source for your counterpoints. So the two conflicting points of view are me, who you could make the argument that my beliefs on non-native species borders on the religious and therefore makes me blind to alternatives. And Crown Bees, which is a Business trying to make money, no shame in that, I love money, but does color the information they dispense through the filter of what gets them customers. So while I would forgive any who thought my position borders on the fanatical and therefore unreliable, you should also consider that Crown Bees isn't unmotivated in what they say either.
Now as I said earlier, I hate government involvement. I am not campaigning to get people to write their congressmen or any of that BS, what I am doing is:
1, Convince people who have yards and want to help native bees to not add further competition by adding these.
2, Raise the point to people who want the pollination service that working with the native population is not only much more beneficial (from both the pollination standpoint and the environmental standpoint), but is doable.
I was not intending to put this on a listserve, I think it would be a little rude for me to enter a forum and the first thing I do is attack one of the members. I don't like it when new people come onto the iNat forum and do that, so I don't want to do it elsewhere. And from what I've seen, a lot of these forums don't like it when a debate gets to "spirited" which I imagine it would: on one side you have a fanatic and on the other you have a business man. It'd stay polite for, say, 4 responses.
However, if you look into some of the things that Sam Droege, Sheila Colla, John Ascher, ect have said regarding these bees and beewashing, I think you'll find there wouldn't be a lot of differing opinions.
I'm only familiar with that one company Crown Bees (CB), which is why I focused on it, but have no affiliation and don't know the person who works there. But, that company is relevant because they claim to avoid many issues that could otherwise be a problem for companies selling bees. CB claims to be one of four companies using certified bees and explains their bee sourcing and the precautions they take against pathogen spread. I assume if they had been asked, they'd also say they don't believe their bees are causing new introductions. I can't comment on how most or all other companies selling bees compare to CB, but assume there are others who also take those extra steps, in addition to others who may take less precautions. There, I'd point out that there should be or may already be policy restrictions on the practice of releasing bees that affect all companies, so it's not that even other companies can do anything they want. If there happens to a be a problem with how some companies are participating in this practice, then I'd support strengthening policy.
The megachilid species occurrence maps linked to above are pretty filled in, especially when using the map filter to show GBIF data points from external sources. There are also possibly many unrecorded records that aren't on GBIF, which would fill in the distribution maps even more. As for the application of using these bees to research various matters that would also apply to other bees, we'd need to read more about it, but I believe there are applications, which was also briefly implied in one of the cited articles or their citations. A rough analogy is how mice can be used as model organisms in research applicable to people.
We both wondered if not only non-native but also native megachilids could be used to buy to release (and for research). I suspect that the non-native species (rotundata and cornifrons) have at least slightly greater efficiency and/or ease to work with. They're also the main species used in the industry currently, so there would be difficulty adding a new native species if there weren't sufficient customer or supplier-company interest/demand. Possibly, the choice of species being sold to release may also be affected by only certain species being allowed by existing policy/licenses, and/or for their long history of use in agriculture and related practices, similar to Apis mellifera. I think some native bee species have been released on smaller scales, at least in some research or agriculture contexts, although what we're referring to above is if one could be used widely in place of the species mentioned. Anyway, it would be very interesting to learn if native species could be used and what chance there is of that being done in the future. It would also be interesting to learn more about the research, extent/severity of detrimental effects thought to be only due to current practices of releasing megachilids, how the possible downsides compare to problems caused by honeybees, etc.
As for the listserv, yeah you don't have to post it there, but I didn't think it would be a debate that would offend anyone. Because since there are studies about concerns over transporting bees, it's fair to have a discussion about them. Something like, do overall pros outweigh cons, or to what extent do the potential problems apply to current practices being used, and are there justified uses. Or, what can be done to improve the problems if it's also assumed that the practice will continue. People working more directly in fields that use those bees would also have more knowledge from experience they could add to further inform this discussion. Anyway, it's an interesting topic. I've shared all the info. I have for now, although would be interested to read if others had opinions.
Thanks for reading and discussing, I enjoyed it. To clarify one point though, I am against transporting any bee species, native or not. When I say "work with natives", I'm more referring to working with local populations that are already present on the ground which may or may not be Megachilids. For example, someone I talked to who released Osmia for pollinating his berry bushes said that he noticed significantly more Andrena on the bushes than Osmia in the end.
Sounds good.
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