Pink bollworm eradication continues

The future epitaph on the pink bollworm’s tombstone could include the etching “R. I. P. – Rid of Insect Pest.”

Efforts to eradicate the pink bollworm, a.k.a. the “pinkie,” from Western and Southwestern cotton fields are on track under the Bi-National Pink Bollworm Eradication Program.

In Arizona, the program is operated by the Arizona Cotton Research and Protection Council (ACRPC), Phoenix, Ariz. The ACRPC is an Arizona agency funded by bale assessments, federal funding, and by the group’s biocontrol program. The group receives no state general fund dollars.

For decades the pink bollworm has been a strapping nemesis for cotton growers. Pinkies damage squares and bolls. According to the University of California Statewide Integrated Pest Management program, pink bollworm larvae burrow into the bolls to the lint to feed on seeds. As larvae burrow, the lint is cut and stained causing severe quality loss. Pink bollworm damage has reduced grower income by about $32 million annually, according to the National Cotton Council.

California has maintained the San Joaquin Valley’s (SJV) pinkie-free infestation status for four decades with sterile moth releases. About 180 native pinkie moths were found last year mostly in three fields south of Fresno, Calif.

“These were probably introduced through contaminated cottonseed,” said Clyde Sharp, Roll, Ariz., cotton grower and ACRPC board chairman. “The moths were controlled with sterile moths. Pheromone treatment is scheduled for this year.”

Sharp provided the latest pink bollworm eradication details during the joint annual meetings of the Arizona Cotton Growers Association and the Arizona Cotton Ginners Association in Rio Rico, Ariz., in May.

Successful eradication is based on mapping, detection, and control, Sharp says.

Field mapping is achieved through global positioning system (GPS) technology. Every cotton field is GPS-mapped. A plane, with the GPS-mapping software and the recorded field coordinates onboard, flies 500 feet above cotton fields for precise sterile pinkie moth release. A sterile moth that mates with a native moth cannot produce offspring.

In addition to California, sterile moths are released in Arizona, New Mexico, West Texas and northern Mexico.

The steriles are raised at the Pink Bollworm Rearing facility in Phoenix, Ariz. The lab will produce about 5 billion moths this year for release over the West and Southwest, and Mexico.

Detection includes traps placed on field perimeters. Mating disruption using pheromone ropes is placed on the plants. Both are checked weekly.

Control includes cultural practices, Bt cotton, mating disruption, sterile pink bollworm moth releases, plus insecticide only when necessary. Bt technology developed by Monsanto is incorporated in most Upland cottonseed for planting. The Bt trait is an endotoxin that kills pink bollworm larvae in the plant. Pima cotton does not include the Bt trait. More sterile moths are applied to non-Bt fields.

“Transgenic Bt cotton gave us the one tool we needed to get us over the hump in pink bollworm control,” Sharp said.

Successful eradication efforts are resulting in few native pinkie finds in many cotton areas. A portion of Arizona, the last state to launch eradication efforts, should achieve eradication by next year. Central and eastern Arizona cotton growing counties will have completed four years of program activities.

Insufficient funding caused pinkie eradication in Arizona to be staggered across three regions; each starting a different year. A grower-approved statewide referendum passed by cotton growers in 2005 required complete eradication within four years for each region.

The latest Arizona region to launch pink bollworm eradication is Yuma County (2008).

Native moth finds in traps dropped 99.6 percent from 2007 through April 30, 2009. The northern section of Mexico’s state of Baja California began eradication at the same time.

Colorado River counties launched eradication in 2007 including Riverside and Imperial in Southern California and Arizona’s La Paz and Mohave counties. Eradication also began in Mexico’s state of Sonora.

Reduced native catches occurred in Mohave and La Paz counties last year and cut bolls yielded no larvae. In recent years, cotton growers in the two counties planted 95 percent Bt cotton and 5 percent non-Bt due to an Environmental Protection Agency (EPA) refuge requirement.

The ACRPC convinced the EPA to change its 95/5 ratio rule to allow 100 percent Bt for all Arizona cotton regions. This allowance came after an EPA-sponsored scientific advisory panel was shown that sterile moth releases over Bt cotton would provide a substitute for non-Bt refuge-produced moths.

“100 percent Bt, few acres in non-BT cotton, and the sterile moth program are allowing us to get the eradication job done in Arizona,” Sharp said. “After three years we are very close to eradication.”

Eradication began in eastern and central Arizona, plus New Mexico’s Hidalgo County in 2006. No larvae were found in bolls picked and cut last year in southeastern Arizona.

In Maricopa County, 1,800 natives were captured last year. ACRPC trapping efforts proved that the moths were coming from Western areas including Yuma plus San Luis and Mexicali, Mexico.

“With eradication efforts started last year in the Western areas, I think we’ll see eradication accomplished in Maricopa County without any problem,” Sharp said.

The latest pinkie reduction percentages by Arizona county include: Cochise County, 99.69 percent; Gila, 100 percent; Graham, 99.98 percent; Greenlee, 100 percent; La Paz, 98.04 percent; Maricopa, 99.38 percent; Mohave, 96.65 percent; Pima, 99.82 percent; Pinal, 99.87 percent; and Yuma, 99.6 percent.

More than 2 billion sterile pink bollworm moths were released in Arizona cotton fields in 2008. About 1.5 billion moths or 55 million per week are scheduled for release this year. About 45 million/week will be released in the San Luis-Mexicali areas.

The bi-national program was launched in West Texas, most of New Mexico, and Mexico’s state of Chihuahua in 1999 and 2000. A dozen native pinkies were captured last year just south of El Paso. In the El Paso-Trans Pecos (West Texas area), .00017 native moths were caught per trap last year.

“That’s about as close to eradication as you can get,” Sharp said.

No moths were captured in south central New Mexico last year. No larvae have been found in cracked bolls over the last four years.

“For all practical purposes, New Mexico is eradicated of the pink bollworm,” Sharp said.

The ACRPC and Monsanto are developing a proposal for EPA consideration to allow 100 percent Bt cotton plantings in all West and Southwest cotton fields, a practice already in place in the eastern Cotton Belt.

Part of the proposal is defining when an area is deemed eradicated from the pink bollworm. The National Cotton Council Pink Bollworm Action Committee accepted definition states, “An area may be considered ‘eradicated’ after a year in which no evidence of a reproducing population is detected.”

Once eradication is declared by each state and its leadership, planned control activities would end, yet high-level monitoring would continue.

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