Part 1: A Little about Bumblebees and Neonicotinoid Insecticides
Life as a Bumble Bee
|Bombus ssp. on wild geranium|
So you are a young queen. It’s early spring and some combination of time, temperature and length of day has caused you to awaken from your winter hibernation, or diapause. You pull yourself out of bed--the hibernaculum you dug for yourself last fall after you had left your birth nest and mated--scramble out from under the dry leaves that cover the area, and survey the landscape. If you are lucky, you’ve emerged in an area where there are plenty of spring-blooming flowers. You will, assuming you evade hungry predators and don’t succumb to mites or disease, live a happy, if short, bee life. You’ll fly for several weeks feeding on pollen and looking for a good nesting area, which might be at ground level or just below--perhaps under a tussock of prairie dropseed grass, or in an old mouse nest. Then you’ll settle in, lay eggs, and provide pollen for and raise your first group of daughters. Subsequently, while you retire to lay more eggs, they’ll take over foraging and raising young to keep the nest going, ensuring the survival of the next year’s population. Along the way, countless plants will be pollinated, allowing fruits and vegetables to grow and ripen. As a result of your efforts, and those of the thousands of other bee and pollinator species, life on earth will continue.
The foregoing is how life has been for at least 100 million years, since plants first required something other than the wind to pollinate them. Despite the danger, suffering and death that are the unavoidable results of the laws of nature, bees and plants have cooperated to help co-create our planet’s fertility and abundance. However, circumstances have changed more in the last hundred years than in all the millions of years before. We humans, full of the eternal desire to grow healthy crops more easily--not wrong in itself--have finally become numerous enough, have developed chemical weapons dangerous enough, and have destroyed habitat enough that the countryside has become a killing field for pollinators, while, paradoxically, their best hope for survival may very well lie in our urban areas.
An Introduction to Neonicotinoids
|Bumblebee on spiderwort|
However, rarely in the history of the human race have we understood the wisdom of restraint, or the idea that more is not always better, particularly when we act in a linear fashion without considering systemic consequences: a failing which has led to a lot of bad pop music, the over-planting of elm trees in American towns and the collapse of empires, among other things. Consequently, like nearly every other aspect of our industrial farming system, we could say that the use of neonics has been overdone, since they are the most widely-used insecticides on the planet, used to treat hundreds of millions of acres of crops (approximately 200 million in the U.S. alone), not to mention their home garden applications. (This is of course leaving aside the whole questionable philosophical assumption that industrial farming is based on sound reasoning--or ecological reality-- in the first place.)
The thing that makes neonics different from many other insecticides is that they work systemically. Many formulations, such as insecticidal soaps, you might spray on the plant. The rain might wash them off, or new growth will not be protected so that, though they are lethal, the effects might be somewhat limited. Modern neonics, unlike the nicotine teas of yore, are systemic and permanently at work as long as the plant is growing, besides which they stay in the soil to “protect” successive generations of plants for several years. The insecticide is expressed throughout all parts of the plant, including pollen and nectar. This is bad news for insect pests, of course, but unfortunately the plant also spends a lot of energy producing foodstuffs attractive to pollinators and is serving them a poisoned banquet.
Thus farmers who plant corn treated with the neonic Clothianidin (the coated seed is a nice pink color) are helping guarantee that colonies--whether of honeybees in the hive or bumblebees in the wild--will decline in areas where life as a bee is already chancy owing to destruction of habitat and mites and disease. Bees don’t eat usually corn pollen, but as they fly about, foraging, enough gets on their bodies that it travels into the hive, or nest, with them. More worryingly, neonics are used on other plants that do provide abundant bee food. Cotton, canola, potatoes, sugar beets, pears, apples, leafy vegetables...the list goes on and on. My cotton t-shirt, your salad eaten at a restaurant, his stir fry made with canola oil--even if we ourselves don’t use neonics, we’re all involved, one way or another. And ornamental gardeners and commercial growers who use something like Bayer three-in-one rose food with the neonic Imidacloprid as an ingredient are growing toxic flowers. Commercial growers of garden plants also use neonics to treat their potting mix, so the annuals you bring home from the garden center might also carry poisonous pollen.
|Bombus ssp. on Dutchman's breeches|
Bumblebees and other wild native bees are in deep trouble. They are perhaps even more dependent on undisturbed habitat than honeybees. A number of studies have shown that even doses of neonics considered sublethal by manufacturers and regulatory agencies can build up in nests over time to deleterious effect. And bees are exposed to a vast array of chemical agents besides neonics. A recent study published in Nature, for example, demonstrated that sublethal doses of imidacloprid and a pyrethrin insecticide had negative effects on bumblebee nests and populations: because foragers didn’t bring back enough food and some failed to return to the nest, more foragers went out. As a consequence, there were not enough workers to tend the young and not enough young survived. Queens and workers failed to mature. Decline ensued.
Studies like this one, combined with others equally dismal focusing on honeybees and added to strenuous protests from beekeepers, were enough this year to persuade the European Union to temporarily ban the use of neonics for two years, to see whether bee populations could recover: a sensible move, in my book, although, owing to neonics’ persistence in the soil and in perennials, two years might not be long enough to demonstrate highly conclusive results. Meanwhile, in the U.S. the EPA announced that they would continue thinking about things at least until 2018.
The Importance of Urban Areas for Bumblebee Survival
"My" bees, the ones who hang out in my backyard, seem to be ok. They are fortunate because they live in an urban community where many residents garden, often with native flowering plants, and few use insecticides. Beekeeping was legalized in 2012, wild bee populations seem stable, and the town functions as a sort of bio-reserve for bees. Part 2 will explore how urban areas have come to be so important, and what urban dwellers (which is most of us, after all) can do to help.
Note: References will be listed in Part 2. Photo credit: Heather Holm's blog Restoring the Landscape with Native Plants is full of useful information about native plants and pollinators for residents of the Upper Midwest. Cross posted at Resilience.org.
Flowering Plants that Native Bees Love
Attracting Native Pollinators
Let's Talk about Bees
Alfalfa and Our Future