LBAM Not A New Pest?

The light brown apple moth, a native of Australia that was first found in the mainland U.S. in late February, might not be so new after all. James R. Carey, a University of California (UC)-Davis entomologist noted for his research on the Mediterranean fruit fly invasion in the 1980s, says the moth “was probably here for a very long time prior to its discovery and it’s probably far more widespread than currently delineated.”

The pest was discovered in the San Francisco Bay Area back yard of a retired entomologist specializing in moths, Jerry Powell, and that’s no coincidence, suggests another UC-Davis entomologist, Lynn Kimsey. “Jerry found it but nobody was looking for it,” says Kimsey. “There’s no effective surveillance system set up for this kind of thing and there should be. If he hadn’t found it, how soon would we have known about it?”

The moth infestations had been limited to the Central Coast and Bay Area until mid-July, when discoveries were made in Solano County to the north and Los Angeles in the south. Entomologists are concerned because the moth has a broad range of host plants with more than 250 plant species known to be susceptible to attack. Major domestic hosts of concern are stone fruit (peaches, plums, nectarines, cherries, and apricots), citrus, apples, pears, and grapes. Besides Australia, light brown apple moth is found in New Zealand, Ireland, the United Kingdom, and Hawaii.

The question of how long the moth has been in the state may be moot in terms of eradication if it is already well established. Once a pest has a major foothold, says Carey, it is very difficult to eradicate it. “While state and federal agricultural officials often talk about eradicating a population, in reality, this requires eradication of thousands, perhaps tens of thousands, of mini-population pockets,” he says. “Thus, anything short of 100% elimination of these thousands of pockets is control, not eradication.”

Bt Sprays; Grower Alerts

But officials haven’t given up hopes of eradication, and have embarked on spray programs in two areas of concern to winegrowers, the Contra Costa County community of Oakley, and in Napa. They have begun a series of six Bt sprays, and have set out hundreds of traps in the area. As of mid-July, no moths have been found in any vineyards, but growers are still obviously concerned, says Jennifer Kopp, executive director of the Napa Valley Grape Growers Association. “We have confidence that the ag commissioner is addressing the problem,” she says. “But as with any pest, it’s wait and see.”

That doesn’t mean that the association isn’t taking action. When the moth was found in Napa, they sent out an e-mail/fax blast to all growers, as well as putting an alert on their Web site and including information in their newsletter. They also sent out a packet of information to growers that included photos of the pest, says Kopp. “Then they can post photos in the shop where field workers can see them,” she says. “Field workers usually find these things first, and they don’t necessarily speak English.”