Over the past 10 years or so, massive die-offs of the European honeybee—a phenomenon known as colony collapse disorder (CCD)—have sparked increasing concern about the fate of agricultural crops with the loss of these important pollinators. At the federal level, a White House Pollinator Health Task Force was formed and in May 2015 released a national strategy for pollinator protection.
In support of that effort, a number of states are following up with plans of their own. In Wisconsin, professor Claudio Gratton and postdoctoral research associate Christina Locke PhD’14 from the CALS Department of Entomology were invited to partner with the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) in leading a broad array of stakeholders to create a state pollinator protection plan.
The goal of the plan is to provide best management practice recommendations and educational materials for beekeepers, growers, pesticide users, homeowners and landowners who want to improve the health and habitat of managed and wild pollinators. A draft of the plan was open for public review as of this publication’s press time in early 2016, with the final report expected soon thereafter.
How bad is the bee situation in our state?
Locke: We have had very few reports in Wisconsin of colony collapse disorder, a phrase I don’t like to use because it refers to a collection of symptoms rather than a specific disease. One identifying characteristic of CCD is the disappearance of worker bees. Beekeepers go out to their hives and have a healthy queen and healthy brood cells, but the worker bees have somehow disappeared. That is not happening much in Wisconsin as far as we know.
What we do have are elevated annual losses and over-wintering losses in honeybee colonies. Wisconsin beekeepers averaged around a 60 percent colony loss for 2014–15, which is very high. Beekeepers will tell you that a sustainable loss is between 10 and 20 percent every year. These high losses are due to a combination of things. We’ve had a couple of really hard winters, and the honeybees aren’t necessarily adapted to our Wisconsin winters. So there are some efforts to breed queens that are cold-adapted.
The biggest thing that correlates with colony loss in the U.S. overall is the introduction of the Varroa mite in the 1980s. That correlates with steeper declines more than any other single factor we know of. The Varroa mite doesn’t just weaken honeybees, it also spreads pathogens that cause diseases. Those pathogens can spread from managed honeybees to wild bees, too, so it’s something we’re concerned about.
How are our wild pollinators faring?
Gratton: It’s really hard to track populations of our wild pollinators. We manage honeybees. We move them around, we keep track of numbers, we can open up the hive and see what’s going on. With the native bees, there are more than 500 species in Wisconsin. In any one system like apples or cranberries, we may have 100-plus different species that visit them. But many of them are solitary and sometimes rare. We haven’t really been tracking their populations very well. So to know if they are declining, we need a reference point and we don’t have one. As a consequence, we actually don’t know that much about how populations of the native bees are doing.
The few studies that do exist have looked at historical data and suggest that for the most part, most native bees probably haven’t changed that much over time. The few native species that we do have better data on are the bigger, more iconic pollinators like bumble bees. There is some good evidence that these species are declining in North America. And you can point to a couple of species that really have shown dramatic declines compared to midcentury distributions. There may be reasons for those declines—again, having to do with pathogen spread, competitors and declines in flowers in the landscape.
So, is this a crisis for wild pollinators? I think the jury is still out on that. I think there are lots of reasons to be concerned. But I’m not seeing the data out there saying that there is a massive die-off of native bees that we need to be immediately guarding against. This means we may have some time to start helping them out.
We think the way we have approached the plan is helpful because all of the things we talk about in terms of making life better for honeybees are also going to make life better for the native bees. As one example, reduction and judicious use of pesticides.
Also, when you talk to beekeepers and they say, “My bees back in the ’50s and ’60s used to give me 60 pounds of honey per hive every summer. Now I’m only getting 30”—there is not enough food in the landscape out there for honeybees. Food for honeybees—that is, flowers—is the same as food for the native bees. So all of our discussion about habitat management—getting more flowers out on the landscape, making sure those flowers are blooming throughout the entire summer—those are all things that are going to help native bees as well. I think the plan is going to be able to help a lot of other pollinators that can ride on the coattails of honeybees: bumblebees, butterflies and many of the solitary species that we never pay attention to.
What are some of the more surprising or important points in the plan thus far?
Gratton: You can do some relatively simple things and potentially have a big impact. It’s not like you need to transform the world in order to have an effect. Some really common-sense, small things can go a long way.
Locke: For example, in the agricultural recommendations there is a range of simple to more difficult practices. You can reconfigure your entire farm and make sure everything is really diverse and use blooming cover crops and all of that—and then at the other end of the spectrum, there are suggestions like leaving woody debris if a tree falls. Leave some wood so that bees can nest. That’s an example of a beneficial practice that only requires not doing something.
Based on your scientific expertise, what things would help the most?
Locke: For me, it’s habitat. We used to have a landscape in the Upper Midwest that was dominated by oak savanna and prairie. Now it’s not. That’s a lot of acres of habitat to compensate for.
Gratton: And second, as a home gardener or as a farmer, being judicious about killing bees through insecticides. I have to say that most of the farmers that we work with, cranberry and apple farmers, know this. They don’t want to kill off their bees. They are very sensitive to that, so they know the things to do to maintain their bee populations. Also, the beekeepers that they’ve rented bees from would get very mad if you sprayed insecticides during bloom. The farmers, especially of pollinator-dependent crops, know this. They are not necessarily the ones for whom we have to emphasize the importance of not spraying insecticides at especially sensitive times for bees.
What’s the overall hope in doing this work?
Gratton: I hope that people will read this and recognize that insects—in particular bees, but insects in general—play really important roles in our lives. And that, rather than follow our first instinct to squish them or want them to go away, we appreciate them and try to do things that encourage the beneficial ones in the environment. I hope even in a general sense that anyone can read the plan and say, “Wow, I didn’t realize that these little insects, these joint-legged things that fly around, do so much for us that we benefit from. And here are a couple of easy and practical things that I can do to make their lives a little better.” That’s my immediate goal for the plan.
You can view the protection plan at http://go.wisc.edu/pollinator
PHOTO—Entomologist Claudio Gratton and research associate Christina Locke in Gratton’s lab, examining part of a vast collection of pollinators. A new state plan they helped create is aimed at better protecting them.
Photo by James Runde/UW-Madison Wisconsin Energy Institute