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Pink Bollworm: Sterile Release

The Aerial Release of Sterile Pink Bollworm Moths

The Pink Bollworm Program is probably the most successful and longest running yet least known area wide biological control programs in the world. For 34 years, program activities have successfully prevented incipient infestations of pink bollworm (PBW) from becoming established in the cotton growing areas of the San Joaquin Valley. The Pink Bollworm Program uses an integrated pest control approach relying on trapping, sterile release, crop destruction infestations below economic impact levels. The program does not use pesticides, but rather uses sterile PBW moths to overwhelm these infestations. Sterile moths are produced at the CDFA/USDA Pink Bollworm Rearing Facility in Phoenix, Arizona. Sterile PBW moths are sent to California daily and released by aircraft over target areas determined by trapping results.

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 pink bollworm damage to San Joaquin Valley cotton.

Poster of Sterile Moth Aerial Release Program

The screwworm fly is a serious pest of all warm-blooded animals. It invaded Texas in 1842 and by 1950 it had spread across the United States. In 1951 it was discovered that screwworm larva subjected to X-ray radiation were sexually sterilized - the first screwworm larva sterilization was done at a San Antonio, Texas hospital using the hospital's X-ray equipment. It was determined that the sterilized insects would mate with "wild" insects and no progeny would be produced. These early experiments led to the mass rearing, mass irradiation, and mass liberation of screwworm larva with aircraft. And, eventually, to the eradication of screwworm in the United States.

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Currently, SIT is included in the arsenal of weapons used against Mediterranean fruit fly, Mexican fruit fly, Caribbean fruit fly, and pink bollworm. 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.

Pink Bollworm, Pectinophora gossypiella, was first introduced into the United States in 1917. The moth spread to southern California by 1965 and in 1967 pink bollworm 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 pink bollworm in California.

The pink bollworms are mass reared and irradiated at the Pink Bollworm Rearing Facility in Phoenix, Arizona, then shipped to Shafter, California for aerial release in the San Joaquin Valley. The moths are flown from Phoenix to Shafter six days a week. The sterile moths are liberated six days a week from a Cessna 206 flying 500 ft. above designated cotton fields in the San Joaquin Valley.