Biodiversity: It’s Not Just about Pandas and Polar Bears

September 13, 2011 | 4:00 pm
Doug Gurian-Sherman
Former contributor

As I slogged into my garden, soaked by recent tropical storms and hurricane Irene, and pushed back the leaves of my zucchini plants, the wild bumblebee emerging from one of the flowers reminded me that I wasn’t doing all of the work in this plot of vegetables.

Bumble bee in squash flower. Photo by Kori Matiessa

About 30 percent of our crops, such as those in the squash family like cucumbers, melons, and my zucchinis, depend on pollinators—part of our unnoticed biodiversity—to produce food.

That got me thinking about three surprising recent examples of the importance of biodiversity to our well-being. Biodiversity, in its most simple definition, is the types and abundance of living things on our planet or in our backyards.  We tend to identify with the big and fuzzy creatures that represent a small fraction of that biodiversity—the endangered polar bears, pandas and tigers that capture our imaginations. But the less noticeable species all around us make our lives better in innumerable ways.

Bees, bugs and money

Wild bees, for example, are important for their role in crop pollination, and may become more so if we can’t reverse problems that are decimating domestic honeybees raised by beekeepers.  A recent study estimated that in California alone, wild bees are responsible for providing up to $2.4 billion worth of food products per year. A good reason for the saying, “busy as a bee!” Alfalfa, our fourth biggest crop, and critical as feed for dairy cows (think of hay), depends heavily on wild leafcutter bees for pollination in many parts of the country.

Wild bees have to come from somewhere. There must be habitat not poisoned by insecticides, and with various kinds of plants that allow them to flourish so they can do their thing for our crops. Landscapes of uninterrupted, seemingly endless rows of crops found in many parts of the country provide less habitat for wild bees, or the many other beneficial insects that make farming possible in the long run. (for more about pollinators, check out the Xerces Society)

Bigger farm fields, with fewer natural areas, leads to more insecticide use

Biodiversity is important on farms for more than crop pollination. Recent work by scientists at the University of Wisconsin and Michigan State University strongly suggest that much greater amounts of insecticide are needed to control pest insects when there is less natural habitat, such as woodlots and fields, near farms.

Ladybeetles (AKA ladybugs), ground beetles, lacewings, bats, birds, and many other creatures flourish in natural areas and greatly reduce harm to our crops. The added insecticide needed to compensate for the work of beneficial organisms in just the seven Midwestern states studied in this research was estimated to be valued at between $34 million and $103 million in 2007.

The increased amount of insecticide needed in those seven states would cover an area the size of Connecticut, about 5,400 square miles.

Our current industrial Midwestern farming systems that consist of huge crop fields and little natural habitat require more insecticide, costing more, and increasing risk to people and the environment, than farms in more diverse habitats.

And let’s not forget the butterflies

Reducing diversity within crop fields also can reduce the number of desirable animals. Genetic engineering, one of the major ways proposed to make agriculture more sustainable, has done nothing to alter the monotonous, industrial agricultural landscape, and in some ways may be exacerbating these problems. Chemical insecticide use is somewhat lower on some biotech crops compared to what it would be without those genes (but this does not take into account the increased insecticide use in the less-diverse landscapes that biotech crops encourage). On the other hand, the greatly increased amount of herbicide on these crops more than compensates for the reduction in insecticides.

Some have argued that the additional herbicide is relatively benign. But several recent studies remind us that it’s not so simple.

It turns out that the herbicide used on most genetically engineered crops, Monsanto’s Roundup (generically, glyphosate) is particularly good at killing milkweed—the only source of food for monarch butterfly larvae—in and around crop fields.

The replacement of other herbicides by Roundup used on GE crops has resulted in the loss of much of the milkweed in corn-belt states.  Monarchs cross these states on their yearly migration to and from Mexico, and another study suggests that the loss of milkweed may be one factor contributing to possible declines in monarch populations. It is not settled yet whether the loss of milkweed is having a substantial impact on the monarchs, though those most familiar with monarch biology suspect it is.

As I have argued elsewhere, we need a new, more diverse agriculture to reverse problems that go way beyond pesticide use. Piecemeal solutions, including genetic engineering, that do not address the bigger structural problems inherent in our agricultural system only tinker around the edges.