State brings wasps into fight against moths

Millions of microscopic wasps are scheduled to be released in the coming months in Bay Area counties, including San Francisco, under a state-led plan to control the light brown apple moth.

Plans to spray the Bay Area this fall with pheromones to disrupt the moth’s breeding has been widely condemned by city lawmakers and residents.

The state received 640 complaints of people feeling ill after spraying occurred in Santa Cruz County last fall, according to California Department of Food and Agriculture officials.

The department announced plans to release tiny, stingless parasitic wasps in affected areas — 1 million per square mile.

The moth — which the state says threatens more than 2,000 varieties of plants and crops — is a pest-species from Australia that has been found in the Bay Area. The moth larvae feeds on crops and can destroy them.

The wasp program will begin in parts of Monterey and Santa Cruz counties as soon as April; the effort will move north into San Francisco, San Mateo and other counties, according to department spokesman Steve Lyle.

The entire 1.6-square-mile Golden Gate Park will be treated with the stingless wasps, according to Lyle. Both species of trichogramma wasps that might be used by the department are native to California, according to Lyle and Ron Whitehurst, a 10-year pest control adviser who works for a Californian company that rears pest-controlling insects.

“The trichogramma is a general moth egg parasite,” Whitehurst said. “It’ll go after a large number of moths and butterflies.”

Parasites don’t generally destroy their host populations, but the massive numbers of wasps planned for release would help overwhelm prey numbers, according to Whitehurst.

UC Berkeley Professor Andrew Paul Gutierrez, whose specialties include pest management, described the plan as “probably ill-conceived” because he doesn’t think the apple moths will ever be fully eradicated.

“It may attack this pest,” Gutierrez said, “but it’s also going to be attacking a whole bunch of other things.”

jupton@examiner.com

Tiny helpers

State officials plan to release small, stingless wasps to combat light brown apple moths.

Wasp species: Trichogramma pretiosum and Trichogramma platneri

Where: Monterey, Santa Cruz, San Francisco, Alameda, Contra Costa, Marin and San Mateo counties

Start date: Tentative April start date in Monterey and Santa Cruz counties, and then moving north into other counties

Quantity: One million wasps per square mile

Source: California Department of Food and Agriculture

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