At a time when their service is in high demand, some beekeepers have accepted the fact that no one knows why bees are dying.

But it doesn't mean they aren't doing anything to overcome the mysterious killer known as colony collapse disorder.

At 41, Larry Pender is a relatively young beekeeper who can't sit idly waiting for answers.

"Just like any industry you have to work with the environment you're given," he said. "I can jump up and down and complain, but you just have to adapt to it."

Pender is tweaking his operation in a few areas, such as nutrition. To boost his bees' diet, he is feeding them pollen substitutes. Bees are getting a limited menu because more farmers are growing single crops, plus there are fewer wildflowers available.

Comparing bees to humans, Pender said, "If you fed someone oatmeal every day, something's going to go wrong with their system."

While moving the bees to different farms helps vary their diet, it also exposes them to strange bees carrying illnesses.

So Pender is breeding out the wimps, bees that can't handle the stress of being trucked around to pollinate.

"The simple way to do it is like coaching in any sport," he said. "You go with the winners. You take the losers out of your operation and go with the beehives that are strong."

Thus he is breeding bees from the hives that don't falter in particular regions.

Cause is a mystery

For the past few years, researchers have been searching for the cause of colony collapse disorder, a phenomenon in which bees abandon hives in large numbers.

Theories on the cause of the disorder are speculation, according to Kim Flottum, the Medina, Ohio-based editor of BeeCulture.com.

"There's some good indication that it's pathogen-based," he said.

But a variety of other things bees are being put through could be affecting them, Flottum said, including poor nutrition, exposure to pesticides and the stress of being trucked across the country to work in unfamiliar fields.

Colony collapse disorder was observed as far back as the 19th century, according to UC Davis Extension apiculturist Eric Mussen, but it became a concern after a massive die-off during the winter of 2004-05.

Today, it's normal for a beekeeper to lose 25 percent of his hives annually. That's up from the 1960s and 1970s, when a Ventura County beekeeper might lose one or two hives out of 500 at the start of the year, Pender said.

As a result of diminishing hives, the demand for bee pollination has surged.

The value of apiary products used for pollination in Ventura County more than doubled from 2006 to 2007, from $147,000 to $356,000.

Bees busy elsewhere

Because Ventura County's apiarists do business outside the county, the rising value might not indicate increased pollination use among area growers. Still, Chief Deputy Agricultural Commissioner Susan Johnson said row crops that need pollination are replacing orchards in the county, which said she believes is increasing local demand.

Colony collapse disorder has been destroying beehives around the country, but does not appear to have devastated California bee colonies — yet.

"We have more than adequate colonies to cover the other crops at the moment, as long as we don't keep losing them," Mussen said.

Almonds are California's biggest crop that requires bee pollination, but fruit and vegetable growers also need bees.

Craig Underwood uses bees to pollinate blueberries at Underwood Ranches in Camarillo.

"We use them every year and put them in when the berries are blooming heavily in November and December," he said.

Without good pollination, he said, you don't get good-sized fruit.