UC Davis entomologists targeting light brown apple moth

It didn't just show up overnight.

The light brown apple moth, the ravenous crop-eating Australian pest detected in at least nine California counties since mid-March, "was probably here a very long time prior to its discovery and it's probably far more widespread than currently delineated."

So says UC Davis entomologist James R. Carey, noted for his research on the Mediterranean fruit fly invasion of California. The medfly, detected in the early 1980s, threatened the state's billion dollar citrus industry, leading to widespread detection, eradication and quarantine attempts.

"Invasions are actually far more difficult than generally believed; they are a process involving multiple steps, each of which can fail," Carey said.

"However, once a pest has a major foothold, it's very difficult to eradicate it," he said.

"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-populations, pockets. Thus, anything short of 100 percent elimination of these thousands of pockets is control, not eradication."

Carey compared the medfly and light brown apple moth invasions to cancer in that it invades undetected, spreads, metastasizes and eventually kills. 

UC Davis entomologist Lynn Kimsey finds it ironic -- and fitting -- that the person who trapped and identified the pest in his Berkeley backyard is a retired UC Berkeley entomologist specializing in moth taxonomy.

"Jerry Powell is a moth taxonomist who recognizes thousands of moth species on sight," she said. "He led the study group on moths at Berkeley before he retired. Now he sets up black light traps (ultraviolet lights) in his backyard and takes insect inventory in his backyard. You could say that ground zero of the moth infestation in California is right in a retired entomologist's backyard."

Powell, who studied the Epiphyas postvittana 20 years ago in Australia, immediately recognized the two pests in his trap as Epiphyas.

Light brown apple moth adults, about a quarter-inch long with a three-quarter-inch wingspan, are light brown, yellowish moths with varying amounts of darker brown. The moth shelters in foliage during the day and flies after sunset and before sunrise. In Australia, it lays up to 1,500 eggs in a clutch, usually three times a year.

The eggs, pale white to light green, are laid slightly overlapping each other as an egg mass or a raft, typically on the upper surface of foliage. Newly hatched larvae are pale yellow-green, while mature larvae are light green with a light brown head.

Frank Zalom, UC Davis integrated pest management specialist who researches tree crops, small fruits, vegetables and invasive species, said the Australian pest is definitely not a picky eater. It eats fruits and vegetables, along with assorted nursery plants and landscape trees. Its appetite spans 250 plant species -- and the spectrum of known hosts continues to grow.

Since identified March 22, the pest has been detected in Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz and Monterey counties. The tally as of June 29: more than 4,300 specimens. Before California, the agricultural pest invaded New Zealand, the United Kingdom, Ireland and Hawaii. 

California Department of Food and Agriculture and U.S. Department of Agriculture officials say the light brown apple moth will adversely affect everyone who buys, produces and sells fruits, vegetables and nursery plants. And as more and more regions are quarantined, the economic noose will tighten.

Should it become even more widely distributed, "quarantines or other types of phytosanitary regulations imposed on shipments of plants, fresh fruits and vegetables could have a major impact on California's $32 billion agricultural economy," Zalom said.

Jerry Prieto Jr., president of the California Agricultural Commissioners and Sealers Association said in a March 22 news release: "If the light brown apple moth impacted all of California's host crops, the total loss of production and control cost could be as high as $133 million."

Said Zalom, "The importance of detecting and controlling leafrollers will increase because it is very difficult to differentiate between endemic species and the light brown apple moth, so there is a high probability of misidentification, which could result in shipments of fruits and vegetables being halted."

Nursery growers can spray the organophosphate insecticide chlorpyrifos to meet standards for shipping. "Commodity treatments with 'hard' insecticides, such as chlorpyrifos, are not possible for most fresh fruits and vegetables, so it is better for growers to closely monitor and manage all leafrollers, as long as phytosanitary certification is required for shipment," Zalom said.

Zalom developed guidelines for just such a strategy for California's $1.2 billion strawberry industry, which accounts for 87 percent of the nation's total fresh and frozen production. Of that, Monterey and Santa Cruz counties produce about 35 percent.

The exotic pest invasion emphasizes the need to "train students to identify insects," said Kimsey, director of the Bohart Museum of Entomology.

"The number of people who can identify insects is shrinking. We lose them to death and retirement before we can replace them," she said.

"Jerry found (light brown apple moth), but nobody was looking for it," Kimsey said. "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?"

Kimsey, who also directs the UC Davis Center for Biosystematics, is among those leading the drive to establish a California Biodiversity Center on campus with the CDFA. It would be the "largest center for identification services of pests, medically important insects and beneficial plants and animals in the United States."

Those who find what they suspect is a light brown apple moth should contact their county agricultural commissioner. More information about the moth, including color photos, its hosts, control efforts, and quarantine maps, is on the California Department of Food and Agriculture Web site at http://www.cdfa.ca.gov/phpps/pdep/lbam_main.htm.