Parasitic wasps battle Asian citrus psyllid

Western Farm Press ran a detailed update on efforts at UC Riverside to identify and release natural enemies of Asian citrus psyllid to aid in the fight against the feared citrus pest and the deadly citrus disease huanglongbing it carries in other parts of the U.S. and world.

Writer Todd Fitchette reported that Mark Hoddle, UC Cooperative Extension specialist in the Department of Entomology at UC Riverside, began releasing the tiny wasp Tamarixia radiata on citrus trees and other plants in Southern California in 2011.

To date more than 160,000 parasitic wasps have been released in over 400 locations spanning 350 zip codes, 64 cities and six counties in southern California, the story said. The counties are Los Angeles, Orange, San Bernardino, Riverside, San Diego and Imperial.

“What was remarkable was we had put out few parasites in relatively few areas (and) they survived just fine,” Hoddle said. “They came through their first winter here in southern California with no problem. That is always the first test: can they survive their first winter?”

Hoddle told Fitchette he is encouraged by the success of the program and by the biological success of the wasp. Since it was first released, it has developed its own breeding populations and has been discovered as far as eight miles away from initial release sites, indicating that it is quite mobile.

Hoddle cautions that the Tamarixia, and another parasitoid called Diaphorencyrtus aligarhensis (Encyrtidae), which could be released in California later this year, are not “silver bullets” in the Asian citrus psyllid/huanglongbing fight. Nevertheless, they do offer hope.

Commercial orchards will continue to spray for the ACP, but urban environments can employ biological control measures when the spray program operated by the state is too expensive to continue.

“As long as we maintain well-irrigated urban environments with plenty of citrus in them the Asian citrus psyllid is going to be here to stay,” he said.

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