Every 60 Days . . . A New Pest on the Block
They are tourists not even a chamber of commerce can love.
A virtual rogue’s gallery of migrant pests--drawn to California’s legendary clime and bountiful opportunities for advancement--are increasingly hitchhiking, sailing and flying into this state, often with devastating consequences: Crop losses alone cost about $1 billion a year.
That doesn’t include the money that cities, counties and the state spend to fight the bugs, or the potential harm done to the environment when desperate growers resort to chemicals.
The insects aren’t slowing down, either, as underscored by last week’s discovery in Tustin of a new insect that felled a 125-year-old eucalyptus tree. The state discovers at least one new pest every 60 days, said Timothy Paine, a UC Riverside entomologist.
From 1955 to 1988, more than 200 exotic insect infestations were discovered in California. During a six-year span starting in 1992, more than 67 were found, according to the state Department of Food and Agriculture.
Several insects have emerged as real hell raisers:
* The state’s $30-billion wine and grape industry, as well as state and private landscaping interests, are threatened by the glassy-winged sharpshooter that migrated years ago from the Southeast. The infestation prompted Gov. Gray Davis to recently ask the Legislature for $14 million to fight the leaf-hopping pest that is destroying the state’s oleanders.
* Thousands of tiny wasps from Australia will be released this month in Orange County and throughout California to prey on the red gum lerp psyllid, which has been bleeding the state’s eucalyptus trees. Discovered in South El Monte in 1998, the psyllids spread almost overnight, feeding on eucalyptus tree fluids and leaving behind messy “honeydew” dropping.
* San Diego has its hands full with the Formosan subterranean termite, which in Hawaii has rendered homes uninhabitable within two years of their arrival. Researchers are still struggling to find a way to control the insect, native to China.
And remember the fruit fly?
Just when it seems one type of fruit fly is reined in, another shows up to take its place. Fruit flies have forced the state to spend hundreds of millions of dollars on eradication efforts in the last 10 years, said Larry Cooper, a spokesman for the state Department of Food and Agriculture.
“The last couple of years we’ve seen a greater variety of fruit flies,” Cooper said. “It’s one type of fruit fly after another, none naturally endemic to California.”
Officials and growers fear that the olive fruit fly, which has made it to Southern California, will migrate to the San Joaquin Valley, the state’s center of olive crop production.
Then there’s red imported fire ants and Africanized honeybees, the so-called killer bees. Orange County supervisors approved using $6 million in state funds to eradicate the highly aggressive ant last January. And like it’s name suggests, the hair-trigger tempered bee, a recent arrival, can and has been fatal elsewhere.
It’s no surprise that the epicenter for the state’s infestations is Southern California, which attracts foreign bugs for roughly the same reason it attracts tourists from Illinois.
“Southern California gets hit the worst because the weather’s great and it has wonderful plant diversity,” said Robert Dowell, the primary entomologist for the California Department of Food and Agriculture in Sacramento.
And forget Southern hospitality. California has done such a thorough job of bringing in exotic plant species, insects from India to Germany can feel at home.
The state has literally reaped what it has sown, experts say.
“People plant things where they don’t belong,” said Donald Dahlsten, an entomology professor at UC Berkeley. “Planting eucalyptuses in California was a mistake. We continue to suffer for that mistake.”
And Southern California’s position as a stalwart of international trade and tourism opens up infinite avenues for insect invasions, by land, sea and air. Even if California has some of the most stringent pest exclusion practices in the nation, sheer logistics conspire against the state to allow exotic insects in.
The problem is not new. California has long been vulnerable to exotic pest infestations.
Citrus fruits were routinely destroyed when Orange County was in its citrus grove heyday in decades past. And the turn of the century saw scourges that knocked certain agribusinesses, like the grape and wine industry, clear out of some parts of California.
But recently it has seemed as if the state has been ganged up on by a particularly distasteful band of creepy-crawlies. Often in urban settings.
“We’ve been damned unlucky with some of the pests we’ve gotten recently,” said Dowell, the state entomologist. “A few years ago we had the ash whitefly. You had to be there when your shoes stuck on the sidewalk because of the honeydew they excreted. You’d walk to your car wearing a surgical mask. It was pretty disgusting.”
The damage wrought has become more noticeable, said Nick Nisson, Orange County’s head entomologist, who said insects have been attacking the kind of ornamental plants that abound in urban areas. A case in point: the eucalyptus. Brought to California from Australia in the 19th century, the tree can be found almost anywhere.
Before 1983, there were no known exotic pests attacking eucalyptus trees. In the 1980s, one emerged, the longhorn borer. Since 1990, nine eucalyptus preying insects have appeared.
When Tustin workers cut down a diseased 125-year old eucalyptus last Monday, city administrator and certified arborist Pat Madsen found a new variety of the longhorn borer beetle on one of the logs, showing it off excitedly the way a child would show off a new Pokemon card.
“We’d heard it was around, but hadn’t seen it yet,” said Madsen, who trapped the beetle in a plastic bag for later research. “This guy is tougher to control than the other one. The natural predator that we used to hunt down the original type of borer doesn’t work so well on this one.”
Universities like UC Riverside and UC Berkeley are leading “bio-control” efforts to fight the longhorn borer and other invaders by finding natural enemies for exotic pests. UC Berkeley’s Dahlsten, for example, was in Southern California last week to monitor regional efforts to combat lerp psyllid infestations through bio-controls.
For its part, the California Department of Food and Agriculture this week asked the Legislature to extend a program that uses dogs to sniff out parcels containing fruits and plants, Cooper said. And the state continues to try to strengthen laws intended to crack down on quarantine violators.
The tactics received a further boost when President Clinton recently called for additional measures to be taken against invasive pests, Cooper said.
Still, the entomological chess match between bug and man rages on, with no end in sight.
“No one’s going to say we’re going to stop everything,” Dowell said. “We can use more people following the law. . . . But part of it is just luck. We’ve had a couple of real nasties in a row. It’s like rolling snake eyes. It does happen, and it happens enough that things get in and stay in.”
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Invasion of Them
A variety of exotic pests have crossed borders and oceans to call California home over the years. The state’s place as a international trade powerhouse, the constant movement of people to and from the region and the climate all conspire to make California-- and especially Southern California--hospitable for insects that range from the obnoxiously messy, to the destructive, and to the potentially fatal.
Pest Figures:
9: variety of eucalyptus-attacking pests discovered in the state. From 1983 to 1989, only one variety had been found.
$1 billion: amount of crop losses attributed to introduced pests, accounting for 50 to 62 percent of all specific crop losses.
$130 million: amount of damage the silverleaf whitefly caused in one year.
$30 million: Amount various counties and the state government spend per year to keep exotic pests out of the state.
Source: The state’s Rogers Study Group report, 1998
Some of the unusual suspects:
ASH WHITEFLY
Background: Attacks fruit and shade trees. Found in the state in the late 1980s. Quickly became established, causing defoliation, fruit loss, tree death.
Origin: Middle East and Mediterranean.
Control metod: A parasite from fly’s native land introduced in 1991 to combat spread.
EUCALYPTUS LONGHORNED BORER
Background: Varieties discovered in O.C. in 1984 and 1995. Both attack trees as larvae.
Control: The earlier type of borer has been largely controlled by the larvae of parasitic wasps. The latter type has begun outnumbering the first.
GLASSY-WINGED SHARPSHOOTER
Background: A terror for the state’s $30 billion wine and grape industry, as well as oleander plants. Last fall, the bug destroyed about 200 acres of vineyards worth $1.2 million in the Temecula Valley. It is feared that this insect will migrate north.
Control: Researchers are studying the problem, and may travel abroad to find a natural enemy for the sharpshooter.
FORMOSAN SUBTERRANEAN TERMITE
Background: Commonly makes infested homes in Hawaii uninhabitable within two years. Has a strong foothold in San Diego.
Origin: Introduced 10 years ago from Hawaii, but a native of China.
Control: There are no consistently good controls for this insect. But esearchers have done some baiting with an insect growth regulator that has shown some promise.
RED GUM LERP PSYLLID
Background: The newest invader, detected in 1998, has caused major damage to eucalyptus trees from Sacramento to San Diego.
Origin: Australia
Control: Researchers are searching for natural predators of the bugs.
RED IMPORTED FIRE ANT
Background: The insect is a major problem in the southern United States, and now in Southern California. The ant has an excruciating sting, which in rare cases is deadly.
Origin: South America
Control: A natural enemy that shows promise is the phorid fly, which lays its egg inside the ant. The egg becomes a larva that travels to the ant’s head, releasing an enzyme that causes the ant’s head to fall off. The fly was introduced in 1999. Researchers are also examining the behavior of the fire ants, especially in relationship to water (they’re attracted to irrigated areas) for clues to controlling their spread. Insecticides are also being studied.
Compiled by Julie Bawden Davis and Hector Becerra.
