I am very excited to start a new job as an Assistant Professor at California State University Fresno. Today is my first day teaching, and I’m looking forward to getting back into the classroom. I’m also starting up a lab here, and I’ll be looking for Undergraduate researchers and Master’s students soon. I probably won’t have the lab functioning until winter, so contact me towards the end of the semester if you are interested in undergraduate research. If you are interested in a Master’s degree, please get in touch sooner rather than later.
I grew up in the central valley, so I know this area well. My favorite ecosystems are here in California, and I’m looking forward to working with California bees again. Fresno is also a hub for agriculture, so my work in pollinator conservation will be especially topical here. I already have some project ideas brewing!
Summer vacation started this week, so I took the opportunity to take my daughter into the field with me. We had a great time catching bees, and she is a very good bee catcher! We went to two of my field sites near Austin, and had great bee collecting. Here is my daughter netting bees on flowers: And here she is with a catch (I haven’t looked at it closely yet but I think it is Svastra): At the other field site we found some Anthidium (still need to id her) nests. Here is a mom from one of the nests: And here is a nest. Note the pebbles that are incorporated in the nest. The female collects resin to construct the nest, hence Anthidium are sometimes called resin bees, as are other bees in the same family, the Megachilidae.
It has been a really great spring here in Texas. At first I was worried it would be too dry, as March had little rain. But it rained at the right times for a good bloom. So the bees have been really good as well. Here is a photo of one of my field sites from a few weeks ago, with Helenium and Opuntia in bloom. Check out the water on the ground in the foreground. It has been raining down in Texas! At least a little.
This sets up possible competition between larvae for food and also spread of good and/or bad microbes between brood. I also find nests where each brood has its own leaf partition, so this trait varies. We don’t know why, and I don’t think this variation has even been described before. I hope to work on these bees more in the future to figure out why they vary in how they build nests. Lots of possible hypotheses to test. This kind of natural history is super fun for field biologists, as just wanting to know more about the organisms we study is what motivates many of us in the first place. Unfortunately, there is not a lot of value placed on natural history nowadays, so if you want to do it you have to do it as side projects here and there, like I’m hoping to do with M. inimica. There is still so little we know about these critters, so natural history is still desperately needed!
There has been a flurry of news in the bee conservation world lately. A couple of big papers have been published, one by Laura Burkle et al. in Science and one by Ignasi Bartomeus et al. in PNAS. Laura Burkle’s paper looks at a famous historical dataset from Carlinville Illinois, and adds present day collections and collections from the 1970s to look for declines in bees. They find rather drastic declines in bee species, and while the pollination networks appear stable for now, the loss of pollinator species doesn’t bode well for the future. The tough thing about these data is that the old dataset had no record of sampling intensity or bee abundances besides broad classifications. So comparing to present day data is tough, but the findings of Burkle et al. are still a red light.
The paper by Bartomeus uses museum collections to look at bee populations across the northeastern US, and comes to a different conclusion. While the museum collections agree with other studies (including mine from San Francisco) finding declines in bumble bee species, other bee species are fluctuating, but overall species richness does not appear to be significantly declining. They cite a study stating that human land use has increased in the study area, but there has also been shifts away from farming in the Northeast. Quantifying land use change in their study area would have been very interesting. Perhaps land use change can explain some of the turnover in bee species over time, or perhaps the turn over is just part of the natural variation in bee communities. Bee biologists have known for a long time that bee communities vary greatly from year to year. But perhaps the northeast bee community is not in decline because land use change has not been as drastic in the northeast as in other areas.
The third bit of news is not published, but there have been early media reports of heavy winter losses in honey bee colonies. Colony Collapse Disorder (CCD) attributed colony losses have declined over the previous 2 winters to levels around 20% losses, but it sounds like this winter may have been the worst year yet. There is still no smoking gun as to the cause, but these losses should be another red light. We need to act fast to figure out what we can do, and we need to continue to research the other pollinators out there, as a sort of insurance if commercial honey bee cultivation continues to face these challenges. For CCD, we need more research looking at the newer pesticides out there, especially looking at combinations of pesticides, pathogens and other factors and how that affects bee health. The pesticides undergo some testing on their own, but very little testing for combined effects is done.
Finally, to add to the mostly dreary news, there are alarming reports that monarch butterfly populations at the overwintering grounds in Mexico were at record lows this year. And this loss is being attributed not to logging in Mexico (which has been halted), but to changes in farming practices in the US that has led to fewer milkweed plants, which is the larval food source for monarchs and to harsh weather (also likely our fault). These reports are again in the media and not yet published in peer reviewed journals, but the decline appears to be real. So if you are doing any gardening this year, why not add some native milkweed plants? Milkweed flowers are pretty, they will attract monarchs, and perhaps you will help save one of the marvels of the natural world (the monarch migration). Mexico is doing its part to save the monarchs, and we need to step up as well.
I haven’t had time to post much lately, but field season has started here in Texas and I will be posting pictures from this year’s field work. This will be my last season in Texas, and I’m hoping to make the most of it!
In the meantime, I’ve published another paper (Insectes Sociaux 2013 McFrederick) from my dissertation work with sweat bees and nematodes. I had a lot of fun doing this project several years ago, and finally got the work written up for publication. I reared lab nests of a social and a solitary sweat bee, both species that associate with host specific nematodes. Here is apicture of an infected brood cell, from the paper. The dashed arrow points to pollen, while the solid arrow points to a mass of nematodes:
Rearing the lab nests is what got me interested in how microbes affect bee health. But the point of the project was twofold: to figure out if the nematodes affect bee health, and if so, if associating with a social host creates natural selection for more benevolent nematode strains when compared to nematodes that associate with a solitary host. The influence of social structure on symbiont evolution has been posited before, most notably by David Hughes in this TREE article. But David suggested that associating with large insect colonies should influence symbiont evolution, while social halictids live in small colonies, with a couple of exceptions. My data agreed with this suggestion, because I found that both nematodes had small or no effects on host fitness (number of offspring produced):
Augochlora pura is the solitary host, while Halictus ligatus is primitively eusocial. There was a slight trend towards the opposite effect than what I hypothesized, that is that infected solitary hosts had greater fitness than uninfected solitary hosts and vice versa for the social host. But these effects weren’t significant. So either social structure does not influence symbiont evolution in this case, or there are effects that I was not able to detect in the lab.
Raising these nests was a great experience, just looking into the nests every day was really interesting. But it was a lot of work, and I’m not sure I will try to rear halictids again. I’m more likely to rear bees that take well to it, like leafcutting bees!