I received an email from a reader not too long ago who lives on a ridge top outside Scotts Valley. She wrote that her “flowering plums have no ‘buzz’ about them when she walks by. Even (her) rosemary is not a buzz. A few yes, but not nearly the normal. Why is this year different?”
Where have the honey bees gone?
Bees have been in the news a lot especially since 2006 when beekeepers started to report higher-than-usual colony losses. We depend on honey bees to pollinate everything from fruit to vegetables to nuts. Of the 100 crop species that provide 90 percent of the world’s food, more than 70 are pollinated by bees.
Colony Collapse Disorder (CCD) is a syndrome defined as a dead colony with no adult or dead bee bodes but with a live queen and usually honey and immature bees still present.
According to the U.S. Dept of Agriculture, no scientific cause for CCD has been proven. But, I read about recent research that has discovered a link between a family of systemic insecticides and colony collapse. This got my attention.
Honey bees and beekeepers have had to deal with a host of problems from deformed wing virus to nosema fungi, Varroa mites, pests like small hive beetles, nutrition problems from lack of diversity or availability in pollen and nectar sources, and now we are finding out more about the sublethal effects of pesticides.
Insecticide labels warn the user not to spray when bees are present or allow the spray to reach a water source. But what area the effects of systemic insecticides used to control aphids, mealy bugs, lawn insects, grubs, thrips, termites, scale, or leaf beetles on your roses, trees, shrubs and lawn?
The makers of these products that contain imidacloprid, a common systemic, say their studies show that even if a product is highly toxic for insects, it is almost impossible that the insect will ever get in touch with this product and are not at risk.
But that’s not really the whole story. Unlike other pesticides, which remain on the surface of the treated foliage, a systemic pesticide is taken up by the plant and transported to all the tissues — the leaves, flowers, roots, stems as well as pollen and nectar.
Neonicotinoids are a relatively new group of systemic insecticides that are especially effective against sap feeding insects like aphids. They are also being used to treat genetically engineered corn seeds. Applied to seeds, the pesticide spreads through the plant as they grow, attacking the nervous systems of a wide range of corn crop pests.
This is where the recent studies have shown that these pesticides do affect honey bees, but not by outright killing them.
After exposure to pollen from one of these systemics, the bees’ navigational systems seemed to go haywire, and they were several more times more likely to die before they could make their way back to the hive.
Another study has shown that these neonicontinoids can wreak havoc with the bee’s neural circuitry causing them to forget associations between the scents of flowers and food rewards.
A Florida beekeeper sums it up by saying: “The thing is, you don’t have to physically kill the bee. You just have to impair him so he can’t find his way back to the nest. “
Bottom line, protect our pollinators and improve honey bee survival. Plant more plants that provide nectar and pollen for honey bees such as bee balm, agastache, clover, catmint, lavender, yarrow, hyssop, aster, coreopsis, verbena, and black-eyed Susan.
Native plants that are good sources include California poppy, salvia, buckwheat, ceanothus, and toyon.
Use only organic insecticides and avoid applying during mid-day hours when honey bees are most likely to be out foraging for nectar and pollen on flowering plants and only then if you can’t control a pest with any other methods including Integrated Pest Management techniques.
Help save the bees.
– Jan Nelson, a landscape designer and California certified nursery professional, will answer questions about gardening in the Santa Cruz Mountains. E-mail her at [email protected], or visit www.jannelsonlandscapedesign.com to view past columns and pictures.
