CDFA Plant Health


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The Aerial Release of Sterile Pink Bollworm Moths

If a native moth is detected, sterile PBW moths are released over all cotton fields in the section to disrupt PBW mating. Sterile moths are produced at the CDFA/USDA PBW Rearing Facility in Phoenix, Arizona. Historically, sterile PBW moths were sent to California daily and released by aircraft over target areas determined by trapping results, however the aerial release of sterile moths has not been implemented since 2012 as native PBW moths have not been detected in California since 2011.

Placement of Sterile Release Apparatus in the Release Aircraft

The History of Sterile Release

Sterile Insect Technique, SIT, was first introduced as a control for screwworm flies in 1951. It has evolved into a proven method of combating several types of incipient insect infestations. Since 1967, a cooperative county-state-federal SIT program that uses modern technology and scientific practices rather than hard pesticides has prevented PBW damage to San Joaquin Valley cotton.

Poster of Sterile Moth Aerial Release Program

SIT works, by sterilizing the insect with low doses of radiation. The sterilized insects mate with "wild" insects and no progeny are produced.

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Currently, SIT is included in the toolbox used against Mediterranean fruit fly, Mexican fruit fly, Caribbean fruit fly, and PBW. The basics in controlling and eradicating each of these insects using SIT are the same; mass rearing, mass irradiation, and mass liberation of the sterile insects.

PBW, Pectinophora gossypiella, was first introduced into the United States in 1917. The moth spread to southern California by 1965 and in 1967 PBW was detected in the San Joaquin Valley where more than 90% of California's cotton is grown. In 1967 SIT was introduced into the battle against PBW in California.

The PBW were mass reared and irradiated at the PBW Rearing Facility in Phoenix, Arizona, then shipped to Shafter, California for aerial release in the San Joaquin Valley. The moths were flown from Phoenix to Shafter six days a week. The sterile moths were liberated six days a week from a Cessna 206 flying 500 ft. above designated cotton fields in the San Joaquin Valley. Sterile release of PBW has not occurred since 2012.