Taking Aim at Sharpshooter

It is considered a scourge of California agriculture, Public Enemy No. 1 for grape growers.

So it might seem odd that Jake Blehm spends his days hunting the glassy-winged sharpshooter, not to kill the voracious insect but to make it produce as many as 10,000 offspring a week.

Blehm owns Buena Biosystems in Santa Paula, the only company in California contracted to collect sharpshooter eggs as part of a statewide project to control the spread of a pest that has wreaked havoc on the state’s wine industry and threatens other crops.

Every other week, Blehm loads plants peppered with the eggs into the bed of his Ford pickup and delivers them to a research station in Riverside. There, they are inserted into cages swarming with dive-bombing wasps no bigger than grains of rice but which are natural enemies of the needle-nosed insect.

The wasps sting the eggs and lay eggs of their own inside, producing offspring that feed on the evolving sharpshooter and emerge about two weeks later with a singular appetite for their yellow-eyed adversaries.

“That becomes their sole purpose in life,” said Blehm, one of a handful of bug breeders in Ventura County, long considered an area that helped pioneer the use of biological controls.

“People have referred to us as Typhoid Mary, because we are producing this insect that nobody wants, except for researchers,” Blehm said. “But it is gratifying to be part of a project that is contributing to keeping California agriculture viable.”

The effort is one of more than 60 research projects underway across California to battle the half-inch sharpshooter, an exotic pest discovered in the state in the late 1980s after being accidentally brought in from Mexico.

Unlike other pests that feed on fruit, the sharpshooter does its damage by delivering a bacterium that causes Pierce’s disease, which clogs water-carrying vessels in plants and starves them of nutrients until they wither and die. Vineyards are particularly susceptible, although the disease also strikes almond trees, oleanders and other plants.

Though the disease has plagued agricultural areas for more than a century, the arrival of the aggressive, fast-moving sharpshooter has supercharged its spread.

The worst damage has occurred in Temecula, where 1,000 acres of wine grapes have been destroyed in recent years, costing growers $40 million. Smaller infestations have also been reported from San Diego to San Bernardino and throughout the San Joaquin Valley.

State and federal officials are devoting $20 million a year to keeping the sharpshooter from moving into high-priced winemaking regions such as Napa and Sonoma. Just last week, ballots were mailed to Napa County grape growers asking if they would tax themselves $4.51 an acre to support the struggle against the vine-killing insect.

Deployment of biological controls, such as the tiny wasps being bred in Riverside, is key to the long-term sharpshooter battle, said Jay Van Rein, spokesman for the California Department of Food and Agriculture.

“We are getting plenty of evidence from our surveys that we are having quite a bit of success so far,” Van Rein said. “These wasps have got a very finely tuned appetite. They won’t go after much else other than sharpshooter eggs.”

About $2 million has been devoted so far to this micro-war.

The wasps, which pose no dangers to humans because their stingers are so small they can’t penetrate skin, started being released last year and are now buzzing infested areas throughout Southern California and as far north as Santa Clara County.

Because the sharpshooter was accidentally introduced to California, it had no natural enemies in the state. So researchers imported the wasps from Mexico, producing 134,000 of the winged insects last year and the same amount so far this year.

A chief goal of the program is to establish colonies of the wasps in the wild and create a self-perpetuating line of defense against the sharpshooter.

It is not a quick fix, especially against a pest that moves rapidly and in many areas now appears in significant numbers.

“Biological control never has been and never will be a radical response,” said David Morgan, a state research scientist helping oversee the part of the project based at UC Riverside. “But we have to pursue every possible angle for controlling this pest, and we see it as an integral part of an overall control strategy.”

The Riverside facility and one in Bakersfield are producing three species of wasps, all of which have had success controlling sharpshooter populations. Researchers also produce sharpshooter eggs, but have had trouble keeping pace with demand.

That is why they turned to Buena Biosystems, one of the nation’s largest producers of beneficial insects, with about $1 million in annual sales and 500 customers on four continents.

Last December, the insectary won a yearlong contract to produce 10,000 sharpshooter eggs a week. The company started delivering eggs to the research facilities in March. Blehm estimates he has supplied about 100,000 eggs to date, using a rudimentary system of collecting pregnant sharpshooters from local orchards and putting them in plastic-enclosed chambers, where they deposit their eggs on garden-variety plants.

Blehm said he hopes his involvement at this stage will put his company in position to take part in future sharpshooter projects, including any move state researchers make to contract with private companies for wasp production.

He said he is also eager to explore using some of his other bugs in the sharpshooter battle--including the green lacewing, which liquefies its enemies before eating them from the inside out. A lacewing field trial is pending.