Conservation Column Apr 2014: The Birds and the Bees (and the Flowers and the Trees)

Spring is in the air—time to talk about the birds and the bees. Perhaps not “the talk” that first springs to mind, but rather the one about pollinators and how important they are to life on earth (not to mention their financial impact worth over $15 billion in crop value each year). It’s also time to consider why so many populations of bees and birds are in serious decline. A devastating event occurred last summer in the Portland vicinity, when about 50,000 bumblebees were found dead—the world’s largest record for bee deaths. The massive die-off was attributed to dinotefuran (trade name Safari), a neonicotinoid pesticide that was sprayed on ornamental trees in the area.

Neonicotinoids, which are neurotoxins, are now the most widely used class of pesticides. The chemicals have been shown to persist and accumulate in soil. They are water soluble and have been found in the pollen and nectar of treated crops. Several research studies published in scientific journals report the adverse effects of these pesticides on bees, even at sublethal doses. A significant overall colony growth decline can be observed at about two weeks after exposure to neonicotinoids. The chemicals damage the central nervous system, impair learning, and slow brood development. Worker bees exposed to neonicotinoids are smaller and bring back less pollen than unexposed worker bees, and they are also less successful at returning to their hives. Immune suppression has been documented; a recent study found that infected bees exposed to neonicotinoids suffer an increase in viral replication. Exposed bees appear to be more susceptible to colony collapse disorder, and this occurs even when the bees have been foraging on plants that have not been directly sprayed but contain low levels of mixed pesticides due to pesticide drift.

Vertebrates are less susceptible than insects to these neurotoxins, but many researchers believe that the effects on birds have been underestimated. The danger to grain-eating birds was documented when they died after eating very small amounts of pesticide-coated seed. Many people worry about long-term sublethal effects and the synergistic effects of exposure to multiple agents. In addition, there are only one or two typical laboratory test species and nobody knows whether the test findings can be extrapolated to the many different species of birds that might be exposed in nature.

The evidence substantiating the alarming negative effects of these pesticides has caused the European Union to ban the use of neonicotinoids for at least two years while further investigation proceeds. Conversely, the United States Environmental Protection Agency has not banned the pesticides. Here in Oregon, related pesticides were temporarily restricted immediately after the bumblebee deaths last summer. In February, however, a bill that would have restricted their use permanently did not pass the Oregon Legislature. Nevertheless, there were two positive outcomes from the legislative session: The state now requires that licensed pesticide applicators complete a course and pass a test about safe use of pesticides, and a task force panel will investigate bee health. The panel may propose additional bee protection measures for next year’s legislative session. Closer to home, the Eugene City Council voted on February 26 to ban the use of neonicotinoid pesticides on city property. This resolution is the first one of its kind in the nation. Kudos to Eugene for its frank discussion on the birds and the bees.

What you can do: Avoid the use of pesticides in your gardens. Use compost and healthy soil amendments to prevent pest problems. Native plants tend to reduce pest problems and attract pollinators that keep pest bugs in check. Use alternatives to chemicals such as certain kinds of soaps, oils, and herbal repellants. If you must apply anything, go for the least toxic methods and never apply during bloom (wait until flower petals have fallen). For the pollinators, plant a variety of flowers that bloom at different times and include different shapes for different pollinators (hummers like tube shaped flowers, for example). You can find ideas for pollinator-friendly gardening and related information at www.beyondtoxics.org/work/safe-public-places/healthy-bees-healthy-gardens/cultivating-bee-friendly-gardens/.