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In This Issue...
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A Bug’s Life Revisited
Whatever Happened to Aerial Spraying and West Nile Virus?
By Sarah Weston
Amidst the torrents of negative political ads and a global economy presumably in ruins, it’s easy to forget that just a few months ago all our fears were fixated on something as humble as an insect or a seldom-seem disease. Though temporarily bumped from center stage, neither the light brown apple moth nor West Nile virus has exited the stage entirely. Here is an update on what’s been happening with both.
“Stop the Spray” advocates claimed a victory in April when Superior Court Judge Paul Burdick ordered aerial spraying for the light brown apple moth halted in Santa Cruz County until an environmental impact report had been completed. Several weeks later, a judge in Monterey County, the county that has the second-highest population of the moth, issued a similar ruling. Though appealing Judge Burdick’s ruling, the California Department of Food and Agriculture agreed in June to suspend aerial spraying of pheromone-based products over urban areas. Late in September, the CDFA abandoned that appeal entirely.
Sterile Moth Program Proves Successful
CDFA spokesman Steve Lyle said his department’s change of heart had not been due to public pressure over aerial spraying, but as a result of scientific breakthroughs that led them in a new direction. That direction was a sterile release program, where moths that had been sterilized by irradiation would be released and allowed to mate, edging out their fertile brethren.
That technique was developed in the 1950s for use against the screw-worm fly, a pest from Mexico. According to a USDA spokesman, the screw-worm fly had been pushed all the way back to Panama as a result of that program. He cited similar results with the pink bollworm moth in California and Arizona.
Lyle said that the great majority of scientific researchers
had for some time urged his department to move towards a sterile release program. The recent breakthroughs had made CDFA willing to abandon aerial spraying.
“We were able to make great progress, much faster than we thought, on all of those hurdles to get to the point where in June we could announce that the program was shifting directions,” he said.
Unfortunately, not everyone is buying that success. James Carey is a respected professor of entomology at UC Davis and a frequent critic of the CDFA’s handling of the LBAM.
“Unfortunately LBAM is too widespread and too deeply entrenched to have any hope of its eradication with any insect control tool available, the sterile insect technique notwithstanding,” he said.
Among numerous objections, he noted that for such a program to be successful would require rearing billions of the moths per week, and that ascertaining sterile versus wild moth could only be done under a microscope, one moth at a time.
CDFA’s Lyle discounts these objections, saying that sterile insect release has been used around the world for a number of years successfully, including against the Mediterranean fruit fly in Southern California. “Our experience tells us it’s a very effective technique,” he asserted. “We have high hopes for it for the LBAM project.”
The sterile release program is not likely to be fully implemented till 2010 or 2011, according to the state spokesman, and will take years to ramp up to full speed. Lyle states flatly that the CDFA has no plans to return to aerial spraying in the meantime.
“In terms of populated areas, aerial pheromone treatment is off the table,” he said.
With the environmental impact report required by Judge Burdick’s ruling expected next spring, anti-spraying groups are not taking that at face value and letting up their efforts.
Congress to Look at Reclassifying Moth
Congressman Sam Farr of Carmel is pushing the USDA to downgrade the LBAM from Class A (voracious pest) to Class C (minor pest). The petition, which is supported by Dr. Carey and others, states that no damage attributable to the moth has been found in California, and in other parts of the world where it is established, it is no more than an episodic minor pest.
It further claims that current classification of the LBAM is based on out-of-date information as well as incomplete understanding of the moth’s biology.
Far from expanding exponentially as CFDA fears, the LBAM population in California has remained relatively stable, says Farr. He hopes to use his Agricultural Appropriations Committee to pressure the USDA into granting a hearing over light brown apple moth reclassification.
No West Nile Local Cases So Far in 2008
Happily, unlike the apple moth, West Nile virus ended up generating little fear or controversy locally this year.
Santa Cruz County has seen not a single human case of WNV so far in 2008, and neighboring Santa Clara County has seen just one. Most cases have occurred in Southern California, with 122 in Los Angeles and 54 in Riverside County.
Statewide there have been 345 cases amongst humans, down from 361 last year.
Paul Binding, district manager of the Santa Cruz Mosquito & Vector Control District, said, “There’s a lot less activity in the county, as far as birds are concerned.”
WNV is an avian disease, and Binding said just three dead wild birds had tested positive in the county in one recent one-month period, in contrast to 32 in a similar period back in 2004.
Among two flocks of chickens kept by the district as sentinels, no bird has tested positive, nor has any mosquito sample.
Binding acknowledged that West Nile virus this year had turned out to be less of a threat than expected. “We’ve got good control of our breeding sources throughout the county and don’t expect a human case, but we could be surprised,” he said. What constitutes “good control”? He said that his department keeps track of and rechecks every site that has a history of breeding the encephalitis mosquito, which is the main vector for WNV.
“We haven’t had the activity and the hot weather that’s really needed for high virus activity,” Binding continued.
However, he gave significant credit to ordinary citizens in helping mosquito eradication efforts.
“It’s the yard sources where we really ask for the public’s cooperation,” he said.
He urged people to talk with their neighbors about any standing water in their yard, and to report any dead birds or tree squirrels to his agency.
As with the apple moth, he expects West Nile virus to be an ongoing problem we will just have to learn to live with, picking up a clearer and clearer understanding as we go along.
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