Native Pollinators Need a Different Agriculture System
See our California Matters with Mark Bittman segment on native pollinators here.
Imagine being outdoors on a beautiful farm, catching bees and other winged creatures -- for conservation biologist Claire Kremen of UC Berkeley, that's a part of her work when studying native pollinators. She cites that California alone has a diverse species of native bees -- over 1,500 including bumble bees -- but because of our current monoculture techniques, farmers are increasingly dependent on imported honey bees to pollinate many of our crops. Read on as Kremen explains why this has detrimental effects not only on the survival of native species but on our food production as well.
We see you catching bees in the video. What else do you do to conduct your research?
Claire Kremen: We spend a lot of times collecting bees but we're also interested in the pollination process. One of the techniques we use to determine how important each bee species is to follow the bees -- we call it "interviewing the bee" and we present the bee with a flower and we determine how much pollen it actually transfers to the flower. It's important for us to understand the environmental factors affecting the bees and we collect local information for floral conditions and resources for the bees. Since different bee species nest in different places, we try to establish nesting resources -- whether they are in the ground because a lot of bees tunnel into the ground to build their nests, or in wood. We also try to get information on pesticides that have been used on the crops fields and the surrounding landscape where we're studying.
Do you study other kinds of pollinators besides bees?
Kremen: Our focus is on our wild native pollinator communities. There are approximately 4,000 bee species in the U.S. so that keeps us busy. Where we work in California there are about 1,500 species, but at any given place where we're working, there are several hundred species. We look at all flower visitors, so certain fly species, beetles, butterflies, and moths.
Can you explain why monoculture is so harmful to pollinators?
Kremen: When you grow a crop in a monoculture system, there is a huge huge number of blooms that needs to be visited by some kind of pollinator all at the same time because they're blooming at the same time. It doesn't actually provide very good conditions to support our native pollinator communities because there's usually only one kind of blossom and its blooming only provides floral resources for a short period of time, like a week or two weeks. Our native pollinators communities are diverse species that come out at different times and they need more than that two-week bloom period. Basically in California you need something to blooms year-round. Plus the monoculture cropping system doesn't leave a lot of room for nesting systems for our native pollinators. And finally it doesn't support the natural predators of crop pests very well and growers that use monoculture techniques tend to have to use pesticides as well.
My view is that I would like to change the system so we don't have to rely exclusively on honey bees and if we had a different agriculture system we'd be more concerned about promoting our native pollinators for their own sake and for the services they're providing.
What crops in California depend on imported honey bees?
Kremen: Any crop that is heavily pollinator dependent and is grown in a large monoculture will require honey bee imports. So in California that's almonds, melons, sunflowers for sunflower seed production, avocados, raspberries, and there are so many others.
Are these imported honey bees the same species we come across in our gardens and public spaces?
Kremen: Let me clarify that European honey bees were first brought by colonists to provide candle wax, then honey, only recently, since the 1950s or so, to provide pollination service. By contrast, our native bee pollinators are the 4,000 species I mentioned. Most are solitary, but some are social, like bumble bees. But you'll see honey bees all over the place. The ones found in gardens could be from someone's hive, or they can be from a beekeeper's hive, or it could be from individual bees who have escaped from domestic hives and formed their own wild hives. In that sense we have wild, feral honey bees that have escaped cultivation and become naturalized.
How would consumers notice the effects of colony collapse syndrome?
Kremen: That's a difficult one to observe especially for consumers to see that or feel that initially. But I think farmers are definitely starting to see it. They're sometimes scrambling to get enough colonies to populate their fields, especially in the early part in the year. If they've lost a lot of hives, beekeepers will take their strongest hives and split it in two and put half their workers in a new box and add a queen and hopefully they'll build up into a second colony. It's expensive and difficult to do this and it's not really a sustainable practice in the long run, but that's what they do to make up for the numbers. So the beekeepers are really feeling it a lot. The consumers aren't feeling it yet, but they'll see it in enhanced prices in heavily pollinator-dependent crops if we get to the crisis point.
Are there certain parts of the U.S. that are more affected than others?
Kremen: The parts of the U.S. most affected are the states growing most pollinators-dependent crops. Certainly California is a big one. Almonds are not only pollinator dependent, but blooms in February and this is when bees have just gone through winter, so they're at their lowest ebb, and most susceptible. Even if the beekeepers are splitting the colonies, bees don't have much time to build back up.
What's your take on the White House "National Strategy to Promote the Health of Honey Bees"?
Kremen: It's a great first step. It's wonderful we have a federal strategy for pollinator health, and I'm really glad it's not just about honey bees, but that they recognize the need to protect two key species: honey bees and the monarch butterfly.
But my concern is that it doesn't yet go far enough in two ways. The first is that I do not believe that focusing mainly on the monarch is going to sufficiently protect the native pollinators that don't follow its migratory fly-way. There are a lot of other species that exist in other places and have very different habits. So we need to broaden that strategy to include our native pollinators. Secondly, there's attention on the influence of pesticides on honey bees and monarchs, but again, I don't think it goes far enough to reduce the impact it has on these pollinators. A more far-reaching and far-sighted policy would be to promote alternatives to pesticides which this plan doesn't do. We know that many viable alternatives to pesticides exist and we know of farmers who are using organic and pesticide-free methods successfully.
What are some things home gardeners can do?
Kremen: There are lots of ways backyard gardeners can help. Backyard gardens can be real havens for pollinators. There are basically two things to do: one is to plant a lot of different plants that bloom at different times.There are great places to find resources such as the Xerces Society and the North American Pollinator Protection Campaign websites about what to plant. I want to emphasize that diversity is really helpful. A lot of vegetable gardens are diverse. Any time a plant needs a pollinator, that will bring pollinators in the backyard gardens, so that's a real win-win.
The second thing is to try to garden organically. It's very feasible for a backyard gardener to do this and to grow different things will attract natural enemies of pests to your garden plants. There's no real reason for a backyard gardener to rely on pesticides, but if you do need to use pesticides there are a few benign ones that are going to be a lot less harmful so backyard gardeners should pay strong attention and definitely not use neonicotinoids because those are systemic. They can last longer, we don't know how long, and we don't know the doses that pollinators are obtaining. The best strategy is to avoid pesticide use.
Has the drought had an effect on pollinators in California at all?
Kremen: One graduate student in my lab has some concrete data. She has been looking at pollinators in Yosemite Valley and looking at the effects of fire on pollinators. What she found during the two drought years she studied was that when you have a lot of severe fires in combination with a drought, those two factors interact with each other to reduce pollinator species.
Anecdotally, those of us out there observing pollinators think that there has. Our general feeling from monitoring pollinators is that we see the populations dwindling earlier in the summer than usual, possibly due to the dry conditions and lack of flowers. The seasons are getting more compressed, it's getting really hot, and it's dry. But that's all anecdotal. I would expect it to have an influence, but it would be hard to say.