California and the West : Wasps to Put a Sting in the War on Mealybugs : Agriculture: Officials in Imperial Valley hope to stop invasion of pests that ravaged crops in Caribbean, Hawaii.

Pest fighters in the Imperial Valley and Mexicali released swarms of voracious wasps Wednesday in a battle to stem the North American invasion of the pink hibiscus mealybug, which can suck the life out of hundreds of varieties of fruit, vegetables and flowers.

The mealybugs (Maconellicoccus hirsutus) have wreaked havoc in recent years in the Caribbean and Hawaii but had not been seen in North America until they were uncovered a few weeks ago in the border region of southeast California.

One estimate is that if the mealybugs are left unchecked, the tiny but destructive beasts could cause $750 million in crop damage throughout the United States.

For one thing, the mealybug spreads like crazy: A single egg can be wafted by the wind for hundreds of miles and begin the rapid process of setting up a colony with a relentless appetite. The bugs have a particular fondness for ornamental flowers and avocados--the two top agricultural crops of San Diego County.

Fortunately, two kinds of parasitic wasps are the sworn enemy of the mealybugs. The wasps spend their days laying eggs inside mealybugs.

“The wasps are very prolific,” said Stephen Birdsall, Imperial County agricultural commissioner.

The U.S. Department of Agriculture breeds the wasps in a special facility in Puerto Rico and airlifts them into mealybug hot spots when biological countermeasures are required. More releases are planned on both sides of the U.S.-Mexico border.

When the wasp eggs hatch, the larvae devour the mealybugs.

The mealybug is the second invader to be discovered in the Imperial Valley in recent weeks.

The giant salvinia, a virulent water weed that has clogged waterways in Louisiana and Texas, has taken a liking to the All-American Canal, which provides the irrigation water that is the lifeblood of the valley’s billion-dollar agricultural economy.

The free-floating aquatic fern, a Brazilian native that is illegal to possess in the United States, was found in the lower Colorado River on Aug. 5. Within three weeks, traces of salvinia were found in half of the 1,600 miles of canals maintained by the Imperial Irrigation District, the nation’s largest agricultural irrigation district.

The U.S. Department of Fish and Wildlife has declared the canal system fully contaminated.

To fight the salvinia, the water district has released additional squads of triploid grass carp, a pond-grown fish that have been deployed for several years to keep another canal-choking weed at bay: the hydrilla.

“Giant salvinia are not the fish’s favorite food, but they will eat it,” said Imperial Irrigation District spokesman Ron Hull.

But the carp strategy is only a holding action until federal officials get the salvinia under control in the Colorado River. In a river, the salvinia eats up oxygen and kills fish. Fragments break off and are spread by boats and other watercraft.

Officials from the U.S. Fish and Wildlife Department think they have located the source of the salvinia infestation in the Colorado River in an agricultural drain in the Palo Verde area of Riverside County.

The Imperial district has been fighting the hydrilla weed since 1977 but officials fear that the growth rate of the salvinia makes it an even greater threat. “I think it’s going to be worse than hydrilla,” said general maintenance supervisor Jim Luker.

In New Guinea, it took salvinia only three years to cover 250,000 acres of a million-acre lake. The weed becomes a dense floating mat.

If there is good news on the mealybug front, it is that the bug has yet to attack agricultural crops--being found so far in backyard bushes, trees and flowers.

“This is not son of whitefly,” said Birdsall, referring the pest that has done an estimated half a billion dollars damage to Imperial Valley crops in the past decade.

Bill Routhier, area manager for the California Department of Food and Agriculture, said the wasp comes with a proven track record. The wasps helped reduce the mealybug population in the Caribbean by 90% after pesticides proved ineffective.