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 University of California, 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. Cancer invades undetected, spreads, metastasizes, and eventually kills. "The medfly invasion can be described as cancerous in that its development was latent, insidious, chronic and persistent," Carey wrote in "Establishment of the Mediterranean Fruit Fly in California," published in the Sept. 20, 1991 edition of Science. "A long pre-detection period allows medfly populations to spread prior to intervention so that 'early' detection only occurs after substantial population growth."

UC Davis entomologist Lynn Kimsey, director of the Bohart Museum of Entomology, 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 "eiphyas."

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 1500 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.

Since identified March 22, the pest has been detected in nine counties: Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz and Monterey. The tally as of June 29: more than 4300 specimens. The agricultural pest earlier invaded New Zealand, the United Kingdom, Ireland and Hawaii.

California Department of Food and Agriculture (CDFA) and U.S. Department of Agriculture (USDA) 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.

Said Jerry Prieto Jr., president of the California Agricultural Commissioners and Sealers Association 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."

The exotic pest invasion emphasizes the need to "train students to identify insects," Kimsey said. "The number of people who can identify insects in shrinking. We lose them to death and retirement before we can replace them."

"Jerry found it but nobody was looking for it," said 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?"

Kimsey, who 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 pest, medically important insects and beneficial plants and animals in the United States." It would serve the public, aid national security, support cutting-edge research and contribute to public education focusing on the diversity of life on earth, she said.

In its caterpillar stage, the light brown apple moth is a leafroller, rolling up in a leaf. It is polyphagous, meaning "feeding on many."

UC Davis entomologist Frank Zalom, an 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 hosts--and the spectrum of known hosts continues to grow.

It likes just about everything from "a" to "z": alder, alfalfa, apple, apricot, avocado, beans, caneberries (blackberry, blueberry, boysenberry, raspberry), cabbage, camellia, chrysanthemum, citrus, clover, cole crops, eucalyptus, grape, jasmine, kiwifruit, peach, pear, persimmon, plantain, pumpkin, strawberry, tomato, rose and zea mays (corn).

"It's got a good appetite," agreed Alameda County acting assistant agriculture commissioner Gregory Gee when he addressed the Northern California Entomology Club, comprised of university faculty, students, agricultural industry representatives and agency professionals, at their May 3 meeting in Davis. "It even likes pine trees."

The pest has been reported on oak, willow, walnut, poplar, cottonwood alder and pine trees. "The potential for California colonization is high," Gee said.

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.

Carey said it's easy "to come up with 'just so' stories about how it entered the state, but who knows what happened? People/agencies often say they think this or that but they frequently don't really have a clue since it's usually virtually impossible to nail down even the timing of the invasion much less the mechanism."

"The metastases analogy is appropriate--just like cancer, invasions can grow in fits and starts so it might go for decades just hanging on by a thread, but spreading in very low numbers," Carey said. "Don't think of concentric circles in a pond, but spread as encroachment like crabgrass along a sidewalk. This is why it's so insidious."

The moth can penetrate deep into an area with low numbers, Carey pointed out. "There's so much background noise that it's difficult to detect. For example, say that one year , the population infests one of one million apples; then next year one of 200,000, and the next year one of 40,000. In each case, the population is growing by 5-fold annually, but still it's at likely subdetection levels."

Carey suspects that the moth may be so widespread that it may be next to impossible to eradicate, especially in light of its polyphagous nature.

Does he think the population growth of the light brown apple moth is slow and sporadic or rapid?

"It might appear rapid but really could be just a continuation of its current growth rate," Carey said. "Bear in mind that, just as with cancer, which starts off as a single cell and doubles to two cells, four cells, eight cells, sixteen cells, etc., all of which are subdetection, the vast majority of doublings occur subdetection, prior to cancers being detected. But to go from a BB size, which may be borderline detectable, to marble-size, which is much more detectable, requires only a few more doublings. Similarly, with infestations--the appearance of explosion is often more perception than real."

Carey told the New York Times, in an article published June 18, that getting rid of a pest can be challenging. "These pests can be there at subdetection levels for years, if not decades," he told reporter Jesse McKinley. "They operate-cancer is a good analogy-they operate in little pockets and them boom, the conditions come together, both climatic and in microevolution, and then they appear."

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 vegetable being halted."

For nursery growers, "prophylactic sprays of the organophosphate insecticide chlorpyrifos can be made to meet phytosanitary standards for shipment," Zalom said. "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 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 share about 35 percent.

Zalom said his immediate concern is not with the potential damage to California plants, but with potential economic losses due to quarantines and costs of complying with phytosanitary regulations. He believes that with some help from agricultural researchers, California growers "would learn to manage this new pest much as they successfully manage other endemic leafrollers at present. Potential methods would probably include pheromone mating disruption, monitoring and use of a degree-day model to target young larvae with less-toxic materials, and biological control."

The moth is most likely to spread via infested nursery plants destined for commercial, ornamental and garden plantings, Zalom said, so nursery plants must be treated before they are allowed to be shipped from within a designated quarantine zone. The pest also can be found in green waste and other types of plant material, including cut flowers, trees and tree branches, fruits and vegetables.

"Movement of plant material from community gardens that are within quarantine zones should be avoided," Zalom said.

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 Agriculture Web site at http://www.cdfa.ca.gov/phpps/pdep/lbam_main.htm.

Note: For photos of the light brown apple moth, provided by David Williams, principal scientist, Perennial Horticulture, Department of Primary Industries, Victoria, Australia, see http://www.ucmrp.ucdavis.edu/news/lbam.html

Contacts:

James R. Carey
Professor of entomology
jrcarey@ucdavis.edu
530-752-6217
http://entomology.ucdavis.edu/faculty/facpage.cfm?id=carey

Lynn Kimsey
Professor of entomology
530-752-5373
lskimsey@ucdavis.edu
http://bohart.ucdavis.edu

Frank Zalom
Integrated pest management specialist
fgzalom@ucdavis.edu
530-752-0275
http://entomology.ucdavis.edu/faculty/facpage.cfm?id=zalom