(Beyond Pesticides, September 17, 2007) Mediterranean fruit flies were discovered last week in Dixon, California, and federal, state, and county agencies rushed to respond with traps, biopesticide treatment, and sterile mates to prevent the insect from infesting local agriculture. A total of eight Medflies have been found so far, and the three-pronged attack started with an effort to monitor the presence of the Medfly. California Department of Food and Agriculture (CDFA) employees have placed 1,700 fruit fly-targeted detection traps in an 81-square-mile grid. Next, residents within 200 meters of the original finding had their yards treated with the organic compound Naturalyte, the active ingredient of which is spinosad, a naturally occurring extract from bacteria. The pesticide, made by Dow, is approved for use on organic crops, yet the vast majority of its ingredients (so-called “inerts”) are not disclosed. As another biological control, more than 3 million sterile male flies were released last Friday in a 12-square-mile area around Dixon. The sterile males will be deployed on a weekly basis to mate with wild females, helping to eradicate the Medfly population.
This is the first Medfly case in Solano County, according to county agriculture officials. Agriculture Commissioner Jerry Howard said that is fortunate because of the danger caused by the fly. “No one around here could even remember finding one,” Mr. Howard said. “As far as invasive pests, they are the single biggest risk to agriculture.” The Medfly can infest around 260 different fruits, nuts and vegetables, with the damage being done as the it lays eggs inside a fruit and the larvae begin eating that fruit. The life cycle then repeats, spreading through crops, according to Steve Lyle, director of public affairs for CDFA. Mr. Lyle said the medflies were found in neighborhoods and none have been found near fields or crops in the area. “At this point we don’t have any evidence of that,” Lyle said. “We haven’t found it in any commercial agriculture.”
Mr. Howard said the county will continue working closely with both CDFA and United States Department of Agriculture to monitor the situation throughout the next few weeks. Luckily for the county, Mr. Howard said, the other agencies have dealt with the Medfly in the past and have squashed the threat before a full infestation could occur. “They have a lot of experience. They’ve got the system down,” he said. “I’m hoping we are in that category.” Mr. Lyle agreed and said CDFA has a perfect record when dealing with the Medfly. The last victory came two years ago in San Jose. “We were able to eradicate our infestation there,” Lyle said. “We have never failed to eradicate an infestation.”
CDFA had a busy week, as they completed the first round of spraying against the light brown apple moth in Monterey County. The moth threatens 250 species of plant and tree varieties and was first detected near Berkeley in February. Since then 7,744 moths have been found in 11 counties, all but one in Northern California. Checkmate, a pheromone mating disruptor, was aerially applied to a 60-square-mile area from Marina to portions of Pebble Beach over three nights. The compound mimics pheromones released by female moths and is effective for a month, after which CDFA plans to spray the area again.
Despite assurances from CDFA that the synthetic chemical is safe for humans and will not harm the environment, local residents are voicing strong opposition to being the first people ever subject to such a treatment. They are concerned that officials do not have adequate testing data on the compounds to ensure that no damage will occur to human and environmental health. Also, CDFA declared the situation an agricultural emergency, meaning that decisions and notifications were made quickly, leaving little time for the public’s concerns to be heard. The upset bore similarities to the Medfly eradication in the 1980s and early 1990s, when planes sprayed Southern California with the organophosphate pesticide Malathion in an effort to destroy the fly.
In Dixon, state officials are hoping to eradicate the Medfly using directed chemical treatment and sterile mates. “This program is a great example of research and science working to benefit the public and the environment,” said CDFA Secretary A.G. Kawamura. “It wasn’t very long ago that a Medfly infestation meant spray treatments by helicopter. A lot of Californians probably remember that. Now we have a solution that relies largely on biological control. It’s a great example of progress offered by integrated pest management principles.” A quarantine of local produce, which places strict regulations and restrictions on the shipper and receiver of Dixon agricultural products, is also expected to be put in place soon. Lyle stresses the importance of pest population monitoring to evaluate the need for management of the Medfly. “A quarantine is coming, but could be sometime off,” said Lyle. “It depends on if we keep finding the pests. It’s hard to know how to quarantine them when we don’t know how far out they are.”