Domesticated honeybees have been experiencing a worldwide die-off over the past few decades. Science is searching for a cause as well as for a remedy. In the meantime, the pollinator decline is being noticed - especially in grower pocketbooks.
The size of California's almond crop, which is said to be double the value of all U.S.-produced honey, dropped appreciably in 2003 when there weren't enough honeybees to rent or buy for pollinating the blossoms.
''The almond industry in this state has been increasing in size over the years to almost 500,000 bearing acres,'' said Gordon Frankie, an entomologist with the University of California, Berkeley. ''They utilize a tremendous number of honeybees during a time of year [February and March] when it's tough to get good strong colonies.
Almonds, apples, cantaloupes, cucumbers, strawberries, sunflowers, tomatoes and watermelons are just a few of the 100 or so commercial crops dependent upon honeybees for their pollination.
''Estimates vary, but we could be losing up to 50 percent of our honeybees to a variety of causes,'' said Kevin Hackett, a national program leader for biological control with the USDA's Agricultural Research Service in Beltsville, Md. That heavy mortality is the product of diseases, parasitic mites, off-site poisoning and winterkills, Hackett said.
So what are residential gardeners to do? They might start by reducing the amount of pesticides they use, especially when plants are in bloom. They also might think about creating bee gardens.
Bee gardens are becoming more than horticultural chic. They're becoming necessary. If there isn't a vehicle around to tote pollen grains from blossom to blossom, then there's no fertilization. No fertilization means no reproduction. That would be a sizable problem for anyone with a yen for fruit and vegetables or needing forage crops for their livestock.
''Bee gardens can help, but their impacts will depend upon the number and size of gardens in an area,'' said Robbin Thorp, a University of California, Davis, entomologist.
''Nurseries are coming to us, asking what kinds of plants they should be offering people wanting to install bee gardens,'' Thorp said. ''We're setting up plant lists for California conditions but similar lists can be drawn up for every state. Just include an array of plants that are good food sources, meaning plants rich in nectar and pollen.''
Bloom periods change, as do available bee varieties. But you can recruit a sizable population of pollinators to your orchard, flowerbeds or vegetable garden if you provide a steady supply of food, water and cover, UC-Berkeley's Frankie said.
''You want a series of different kinds of flowers blooming at the same time for different kinds of bees,'' he said. ''There are different cohorts of bees that come out in springtime versus those that come out later in summer. Some produce a couple of generations in the same year, like bumblebees. They need a constant source of flowers from spring until fall.''
Never mind flower odor or bloom color when selecting plants for your bee gardens. The bees don't seem to care. And despite the purist passions of lawn manicurists, dandelions and clover attract a great many pollinators.
What you want is bloom diversity, a great many plants flowering at the same time. It's something researchers at Cal-Berkeley call the ''shopping mall effect.''
''You know how it is when you go mall shopping,'' Frankie said. ''You're after just one thing but you see something else in another store window and you buy it. It's the same with bees.''
Insects and Gardens: In Pursuit of a Garden Ecology, by Eric Grissell (Timber Press, $29.95).
On the Net:
For more about bee gardens, check this University of California, Berkeley, Web site: http://nature.berkeley.edu/urbanbeegardens.