Recent concern about apparent die-offs in bees apparently has now led to speculation that cellphone radiation is the cause for bee disappearance. Instapundit has weighed in, questioning with well deserved skepticism the validity of this claim.

Because I am a scientist, I do not try to establish validity of such reports via Google, but via Web of Science, the search engine that encompasses academic literature, both peer-reviewed and not. As far as I am concerned, until data have been published in peer-reviewed literature, any fantastic "scientific" claims are just clamors for attention.

There is no information yet in the scientific literature regarding possible causes of CCD or "colony collapse disorder" as some have tagged the syndrome of the disappearing bees. This is not too surprising, because it appears to be a fairly recent phenomenon, but I guarantee you that because the USDA supports several Bee Research Laboratories in the western U.S., this problem, if genuine, is being addressed by qualified government scientists as I write (if all the bee lab guys I used to know weren't long retired from the lab, I would call one now to get his take on it).

The mere fact that the U.S.D.A. has labs of bee scientists confirms that domesticated honey bees are indeed important to the pollination of crops in the U.S. But as I pointed out in my last post on the topic, they are by no means the only species of pollinator out there. So don't expect any food shortage panics anytime soon.

What of the cell radiation theory then? Cell radiation has been a human health concern for quite some time, and thus the literature on this topic is quite robust. Some studies (but not others) have found increased cell apoptosis (cell death that is orderly - as opposed to sudden and widespread) due to exposure to cell radiation, but even this doesn't mean we should necessarily be alarmed, because all these studies were performed on cell cultures (in vitro), not on real people using cell phones in a usual manner (in vivo). A recent paper (Valberg, P.A., van Deventer, T.E. & Repacholi, M.H. (2007) Workgroup report: Base stations and wireless networks-radiofrequency (RF) exposures and health consequences. Environmental Health Perspectives, 115, 416-424.) examines evidence that radio-frequency radiation (including cell phones) affects actual human health adversely, and concludes that there is no evidence that it does so. In fact, the authors point out (from the abstract):

The possibility of RF health effects has been investigated in epidemiology studies of cellular telephone users and workers in RT occupations, in experiments with animals exposed to cell-phone RF, and via biophysical consideration of cell-phone RF electric-field intensity and the effect of RF modulation schemes. As summarized here, these separate avenues of scientific investigation provide little support for adverse health effects arising from RF exposure at levels below current international standards. Moreover, radio and television broadcast waves have exposed populations to RF for > 50 years with little evidence of deleterious health consequences. Despite unavoidable uncertainty, current scientific data are consistent with the conclusion that public exposures to permissible RF levels from mobile telephony and base stations are not likely to adversely affect human health.

Here is a table from the paper comparing all the sources of RF we are exposed to (sorry about the low resolution):

So my advice is, chat away until further notice - with the caveat that out of caution, avoid giving cell phones to young kids because developing brains are certainly more sensitive to environmental effects than grown ones, models suggest that child heads absorb EM radiation more than adult heads (De Salles, A.A., Bulla, G. & Rodriguez, C.E.F. (2006) Electromagnetic absorption in the head of adults and children due to mobile phone operation close to the head. Electromagnetic Biology And Medicine, 25, 349-360.). Obviously, if anyone had found major health effects yet there would have been a massive response to deal with it by some country.

Back to the bees though. Different species will not necessarily be affected the same way as humans, especially such distantly related groups such as insects, but as of yet I, as an entomologist who does not specialize in bees, doubt that cell radiation is causing CCD. The article quotes some one knowledgeable about cell radiation, not insects, in asserting the likelihood that it does. Most important, bees navigate primarily via polarized light, which is in a completely different part of the EM spectrum from radio waves. How radio waves could possibly impact their use of light for navigation (any more than it does humans' use of light for navigation) is at best nonintuitive, so I would never believe it until I saw the published paper showing me the evidence. I am not holding my breath for that paper to appear.

Other references:

Erogul, O., Oztas, E., Yildirim, I., Kir, T., Aydur, E., Komesli, G., Irkilata, H.C., Irmak, M.K. & Peker, A.F. (2006) Effects of electromagnetic radiation from a cellular phone on human sperm motility: An in vitro study. Archives Of Medical Research, 37, 840-843.

Joubert, V., Leveque, P., Cueille, M., Bourthoumieu, S. & Yardin, C. (2007) No apoptosis is induced in rat cortical neurons exposed to GSM phone fields. Bioelectromagnetics, 28, 115-121.

Remondini, D., Nylund, R., Reivinen, J., de Gannes, F.P., Veyret, B., Lagroye, I., Haro, E., Trillo, M.A., Capri, M., Franceschi, C., Schlatterer, K., Gminski, R., Fitzner, R., Tauber, R., Schuderer, J., Kuster, N., Leszczynski, D., Bersani, F. & Maercker, C. (2006) Gene expression changes in human cells after exposure to mobile phone microwaves. Proteomics, 6, 4745-4754.

Thorlin, T., Rouquette, J.M., Hamnerius, Y., Hansson, E., Persson, M., Bjorklund, U., Rosengren, L., Ronnback, L. & Persson, M. (2006) Exposure of cultured astroglial and microglial brain cells to 900 MHz microwave radiation. Radiation Research, 166, 409-421.

Zhao, T.Y., Zou, S.P. & Knapp, P.E. (2007) Exposure to cell phone radiation up-regulates apoptosis genes in primary cultures of neurons and astrocytes. Neuroscience Letters, 412, 34-38.

Labels: bees, behavior, environmental toxins

I thought about doing a post on all the wasp mimics out there, but within the flies (Diptera) there are plenty, and it clearly evolved multiple times - in most cases, not all the species within the following family are mimics. Obviously it would be some benefit for any insect to be thought a wasp by a vertebrate predator. Flies cannot sting for defense, so some of them just look a lot like wasps so predators will think they can sting. The ways in which they mimic wasps are fascinating.

The following families include wasp mimics: Micropezidae, Conopidae, Mydidae and Syrphidae. I'm surely missing some - don't be shy about pointing it out, all you Dipterists out there.

There is a whole family of bee mimics as well, the Bombylidae (the bumblebee genus is Bombus). They are big fuzzy things (below right), but if you look closely, you will see only two wings, which gives away their lineage - all bees and wasps (and all orders of insects except for the flies) have four wings.

But I'm more interested in the wasp mimics here. I'll start with my favorite, a Micropezid I caught in Costa Rica, at the La Selva research station. These are fantastic mimics, and a still photo just doesn't do them justice because their behavior is an important part of the package. You can see the fly has a pointy abdomen, which helps, and when grabbed, it pokes its abdomen into the grabber's skin repeatedly as if to sting. (Kinda cute, since it's completely harmless.) The other important combination of morphology and behavior has to do with the long forelegs, which end in white tips (which you should be able to see in the photo, along the edge of my thumbnail). In the tropics especially, the long antennae of stinging wasps have white or yellow tips. Flies, as a group, have very small antennae, but this family of flies has long legs. It was a quicker evolutionary step for the mimic species to use its forelegs to mimic antennae, than to develop long antennae itself. So you will see this fly walking rapidly along leaves in the manner of wasps, tapping its forelegs in front of it just as wasps use their antennae. It's really amazing to watch. (Although this fly family is more ubiquitous in the tropics, there are North American species and I have seen them in central Virginia.)

Conopids have a generally different look, mimicking thread-waisted wasps (Sphecidae) rather specifically. A common wasp-mimic morphology is to have a somewhat constricted abdomen, because a distinguishing character of the Hymenoptera (ants, bees, wasps) is a distinct constriction in the first few abdomenal segments, which means that hymenopterans are more or less restricted to liquefied foods, but also allows flexible reach for the abdomen when stinging prey or for defense. The conopids combine this with the elongated abdomen characteristic of sphecid (digger) wasps. I'm not aware of any specific behaviors that help promote their ruse.

Some Mydidae (mydas flies) apparently go for the pompilid (spider wasp) look. According to the source for this photo of Mydas clavatus, Tom Murray, it is mimicking spider wasps in a particular genus, Anoplius. Pompilids have a quite characteristic look of a black body and darkly pigmented wings. The photo on the right is Anoplius.

The syrphids (hoverflies) are not so precise in their mimicry. Here are two, with one clearly mimicking a bumble bee, and the other just looking generally wasp-like with its black and yellow markings. Their behavior does not necessarily contribute to the show; as their common name suggests, syrphids spend a lot of time hovering, which is generally unwasplike.








Thus mimicry takes many forms. It is interesting that some mimics seem to be modeling specific insects while others just seem to have the general look of wasps or bees. Does the selection pressure differ for these mimics, and why? Perhaps the generalist mimics live where there are a big enough variety of stinging Hymenoptera that they don't need to get specific. Why do some converge on specific families? Is there a dominant model present in those habitats? I'll admit up front that I have not done a literature search, so I don't know what is known specifically about the evolution of mimicry in these groups. I just like them because they are so cool.

The only picture of mine above is the worst one by far, of the micropezid. The syrphids and Anoplius come from Forestry Images, a wonderful image database, and the rest are by Tom Murray, and used with his permission. See many wonderful fly images of his here.

Labels: bees, biodiversity, cool bugs, ecology, evolution, flies, insects, wasps

Although Walking the Berkshires beat me to it, I'm still going to put in my two cents about the latest problems plaguing beekeepers these days. After all, I am a hymenopterist (lover and researcher of the order containing ants, wasps, and bees), and I hobnobbed with scientists at the U.S.D.A. Bee Lab in Tucson when I lived there.

One scientist at the lab (no longer there) was Steve Buchmann, who advocated tirelessly for the study of the use of native bees as pollinators. Clearly one reason why this idea hasn't taken off is that native bees probably can't ever be big business, because they are (as far as I know) all solitary rather than social. This means you can't keep several thousand in a box and lug them around.

But even hardworking honeybees are not just a bunch of equipment. They are living organisms that have basic biological needs. The idea that we are just pushing the colonies we have left too far is an intriguing one. The reason bees are overextended is that there are too many disease pressures on them now, especially the notorious varroa mite. Certainly being trucked around the country to work isn't something bees' evolutionary history prepared them for.

Here's one site that claims we aren't as dependent on honey bees as we think. Note that it is from a vegan site advocating that vegans avoid honey, but it makes some valid points about problems with having a large dependence on a single alien species.

Perhaps an answer to the problem would be the use of "Africanized" (a.k.a. "killer") bees. Beekeepers from South America to Mexico have had no choice but to use these, because they always take over as they spread. Africanized bees were introduced to the Americas in the 1950's when researchers in Brazil hybridized African and European honeybees, hoping to create a super pollinator. Not only did they actually create a super agressive hybrid that is hard to handle, but of course the bees escaped and have been making their way north ever since. They have created problems for many native American bees along the way, able to outcompete them for resources in some areas. They are moving northward in California, so perhaps there will be enough wild colonies there soon to do the job.

Bottom line: when domesticated honeybees are around in droves, they may push competitors out. I'm betting the void will be filled, if not by wild Africanized bees, than by all the natives out there that just want a chance at their slice of the pollen pie.

Labels: bees, invasive species, USDA