March 02, 2003
Many have been asking about olive fly control methods. It is a source of irritation to many olive growers that they must compete with Mediterranean growers who routinely control the olive fly with organophosphate insecticides, yet we have a hard time getting much less toxic control methods approved in this country. Currently Spinosad, an actinomycete bacteria derived toxin is used for fly control in California. Mixed with a new fruit fly bait developed by Dow AgroSciences it is available under the trade name GF-120 under a section 18 emergency use permit and is typically sprayed on a small section of the tree weekly from pit hardening through harvest.
The Olive Fly Attract and Kill (A&K) trap which uses a spiroketal attractant and lambda cyhalothrin, a synthetic pyrethroid insecticide, has been approved under section 18. For details go to the California Department of Pesticide Regulations. The traps may be moved to a section 3 by the end of 2003.
Effective Attractants are key to controlling the olive fly. Attractants can summon the fly from hundreds of feet away to a sticky trap or poisen bait. Racemic 1,7-dioxaspiro[5.5]undecane, olean, 5, is the female produced sex pheromone of the olive fly, Bactrocera (Dacus) oleae. It is in a class of chemicals called spiroacetals and is the ingredient in the commercial product Spiroketal. Although not commonly used in this manner, at concentrations higher than those produced by olive fruit fly females the phermone itself has insecticidal and ovicidal activity. 1,5,7-trioxaspiro[5.5]undecane, an analog of the major pheromone component, has been synthesized and tested, and under optimal conditions it was as attractive as the natural compound, but it did not last as long in traps as the natural material. Spiroacetals are common phermones in wood boring beetles and other fruit flies. Spiroacetals will attract only the male olive fly. Yellow colors attract both male and female flies. Ammonia and protein hydrolysate attract both male and female flies.
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There is a less toxic trap which can be make out of a plastic bottle. Paul Vossen of the U.C. Davis agricultural extension office saw this being used in Spain when there last year. The commercial version is filled with a commercial liquid olive fly attractant. Small holes near the top allow the fly to enter and get trapped. The low cost plastic bottle variation was being used in some organic orchards, evidently with good results.
Take a 1-2 liter plastic plastic bottle and drill four to six 5mm sized holes into the neck with a drill or hot wire. A hot paperclip makes about the right sized hole. Fill 3/4 full with a solution of 5% diammonium phosphate with or without 1-2% protein hydrolysate. (A 5% solution would be 50 grams per liter of water.) Ammonium phosphate can be found in any gardening supply store and the protein hydrolysate can be found in health food stores or farm supply stores. Later in the year spiroacetal capsules can be added. Hang traps in tree canopy by wire or string on the south side of the tree at a rate of 20 per acre. In the Northern hemisphere hang on the South side of the tree.