Expect no curtain call for the pink bollworm, the most pernicious pest in Southwestern desert cotton fields, when the heavy drape falls to crush the ‘pinkie’ once and for all.
The near successful eradication of the pinkie is due to an arsenal of weapons: transgenic Bt cotton, sterile moths, pheromone rope, trapping, boll cutting, and limited insecticides.
Eradication of the pinkie continues to near, cotton experts conclude, but is not a done deal.
The pink bollworm, Pectinophora gossypiella, is native to Asia. It first appeared in the United States in Texas’ Rio Grande Valley in 1917.
The PBW devastates cotton and bottom lines. Female pink bollworm moths lay eggs inside the cotton boll. Larvae chew through the fiber to reach the seed and destroy the green bolls.
The four states at war with the pinkie include Texas, New Mexico, Arizona and California. Northern Mexico has made tremendous strides in the eradication fight.
For more than four decades, PBW has been kept out of California’s San Joaquin Valley through an aggressive trapping program to monitor it and by dropping millions of sterile pink bollworm moths to overwhelm any native populations.
Wally Shropshire of Blythe, Calif., the 84-year-old chairman of the California Cotton Pest Control Board and the last remaining member of the original board formed in 1967, said the success of the eradication program in Far West Texas and Arizona has put PBW on the fast track to eradication.
“We are 99.8 percent there,” said Shropshire. “The eradication program has been a great success with the combination of the pheromones, sterile moth releases and Bt cotton.”
Another factor has been plow down rules to prevent PBW overwintering.
Shropshire has always been optimistic Western cotton producers would eventually, “get a handle on the pinkie. I knew we could control it, but I never thought we could eradicate it until we eradicated the boll weevil in the desert cotton growing areas of Arizona and Southern California. That encouraged me to believe we could do the same thing to the pinkie. And I think we have.”
Shropshire said he does not expect the California PBW program to change in the near future.
“Cotton acreage is coming back in the San Joaquin and we need to continue the program to keep a close watch out for the pinkie.”
Sterile moth releases
He expects the pink bollworm rearing facility in Phoenix to continue producing steriles for the foreseeable future. It was built with California cotton grower funding.
So far this year, there have been no native moths trapped in the San Joaquin. Last year by this time there were 29 trapped. When natives are trapped, program managers bombard the find areas with more steriles.
“We have had only one native find in Southern California,” Shropshire noted. This, he said, is due to the successful eradication program. “I am sure it has had an impact on the zero finds this year in the San Joaquin.”
So far this season, 144 million sterile moths have been released in the San Joaquin where there are 300,000 acres of cotton planted. The program is funded by grower assessments.
“I think it makes sense to keep the sterile program going for awhile, even if we do not trap any natives,” Shropshire said. “There is always a pinkie threat from Mexico, although I understand they have been doing a good job there getting it under control.”
Shropshire is stepping down as board chairman. “They have finally accepted my letter of resignation,” he laughed.
He has been trying to step down for several years, but the state has refused to accept his resignations. Bob Hull of Blythe has agreed to take his post.
“It has been a great experience; a great program and I am gratified that I have been a part of something that has achieved such significant success,” he said.
Far West Texas added the pinkie fight to its boll weevil pest eradication efforts in about 2001. Arizona was the last state to launch eradication in 2006.
As eradication nears, the National Cotton Council (NCC) will likely develop a generic eradication definition to fit the cotton states. NCC PBW committees consisting of growers and professional advisers must approve the definition. Official declarations will likely be declared by state governments.
Other instrumental warriors in PBW eradication include: Larry Antilla, director, Arizona Cotton Research and Protection Council (ACRPC), Phoenix, Ariz.; and entomologist Robert Staten, retired director, USDA-APHIS Methods Development Laboratory in Phoenix.
Staten is considered a PBW world authority. He currently consults with the ACRPC, National Cotton Council, Cotton Incorporated, and Mexico.
Antilla and Staten say it is difficult to pinpoint the total financial losses to the cotton industry from the pinkie insect. Years ago, several growers in California’s Imperial Valley spent $200-$400 on pinkie control, not including the yield losses, Staten says.
Antilla points to Arizona Department of Agriculture (ADA) 1080 PBW pesticide control documents analyzed in the mid-1990s. The paperwork suggests the equivalent of 72 million acres of pesticides were applied in Arizona and Southern California cotton fields between the mid-1960s and mid-1980s (pre-BT cotton) to fight the pinkie. Estimated pesticide costs were $1.3 billion.
Potency of Bt cotton
Staten and Antilla concur the single most potent weapon has been Bt cotton.
“Bt cotton was a lifesaver,” Antilla said. “If we didn’t have high levels of Bt planting today we would not be this close to eradication. Without Bt cotton in Arizona, residual populations would have existed forever.”
Antilla, working with the ADA and others, successfully lobbied the Environmental Protection Agency to grant a 24c special use registration to allow 100 percent Bt plantings in all Arizona eradication zones without a refuge area.
This allowed Bt cotton to be seeded to 97 percent of Arizona’s acreage. The percentage was 80 percent to 85 percent before the exemption.
Looking ahead, Staten said, “I think by the end of 2010 we’ll have most of New Mexico, West Texas, Arizona, and Mexico’s state of Chihuahua largely un-impacted by the pink bollworm. We are down to finishing and conquering the pink bollworm in the Mexicali, San Luis and Yuma valleys.”
The sterile moth component is another pivotal piece of the eradication puzzle. The USDA managed and California Department of Food and Agriculture-owned sterile moth rearing facility in Phoenix has raised in excess of 20 billion sterile PBW moths since the program’s expansion into Texas and New Mexico.
The moths are sterilized by an onsite irradiator and fed a red dye diet to distinguish sterile and native moths in field traps. Small airplanes drop the moths 500 feet above cotton fields where the native moths try to mate with the steriles.
From 2006-2009, about 19 billion steriles were dropped on cotton fields across the four-state area plus Mexico. The breakdown: California’s SJV – 970 million steriles; Arizona – 7.6 billion; New Mexico – 1 billion; Texas – 5.5 billion; and Mexico – 2.3 billion.
Sterile moth releases have effectively reduced native numbers. However the rearing facility’s limited moth production capabilities have slowed the eradication process.
A scary glitch occurred at the rearing facility last August. Staten says about 350,000 moths missed the irradiation (sterilization) process. The still-fertile moths were mixed with 2.1 million steriles in a transit container loaded into an airplane’s drop machine. The fertile-sterile moth mix was dropped by a single airplane over the Fabens, Texas area located east of El Paso.
“We are uncertain how this happened,” Staten explained. “We quickly responded with a pheromone rope treatment and future sterile releases in the area. There is no evidence of pinkie reproduction in the Fabens area this year.”
In another setback, tragedy marred the sterile release program in May when an airplane dispersing sterile pinkies crashed in a cotton field in Somerton, Ariz., (Yuma County). Pilot Travis Perkins died. Perkins had logged 4,000 hours in the sterile moth release program. Antilla says the National Transportation Safety Board has not released the cause of the crash.
Antilla says PBW eradication will open new doors for farmers to experiment with non-Bt cotton varieties to increase yields. He hopes eradication will lower the current $32/acre technology fee that farmers pay for Bt cotton.
PBW eradication near
Far West Texas is nearing a decade in pinkie eradication. The El Paso/Trans Pecos area includes about 37,000 acres of cotton and about 3,600 PBW traps. The last trapped native moth was found in November 2009. The last larva was found in 2007.
Overall, eradication is proceeding as planned in the El Paso/Trans Pecos corridor, according to Larry Smith, program director, Texas Boll Weevil Eradication Foundation, Abilene, Texas.
Last year’s fertile moth release hiccup in the Fabens area was a concern. Fabens area farmers grow about 7,500 acres of cotton.
In response to the fertile moth drop, the foundation directed most of the available steriles for the area to be dropped in the Fabens area. Pheromone rope was placed on cotton plants from south of Fabens to the El Paso city limits.
“The El Paso/Trans Pecos area was essentially eradicated until the fertile moth drop,” Smith said. “It looks like our efforts with the extra steriles and rope are paying off. We have not caught a single native moth in this area this year.”
New Mexico has about 30,000 acres of cotton statewide. Joe Friesen, program director, South Central New Mexico Pink Bollworm Control Committee, Las Cruces, manages PBW eradication in the southwestern counties of Dona Ana, Luna, and Sierra (13,000 cotton acres). The tri-county area is in the monitoring phase.
Friesen reports the last native adults were caught in 2007. The last larva found in a cut boll was in 2004.
“To have zeroes is a good feeling,” Friesen said. “We’ve been able to knock them out. If we can hold our ground, things will be fine.”
Arizona cotton growers narrowly defeated a PBW eradication referendum in 1998. Growers then passed a referendum in 2004 by an 80-percent-plus margin. The referendum requires eradication in each of Arizona’s three eradication zones within four years.
“In this regard, we have a statutory timetable; not a biological timetable,” Antilla noted. “Thanks to the effectiveness of the tools available, the two timetables have coincided.”
Approximately 4,000 traps statewide are checked weekly.
Area One eradication was launched in eastern and central Arizona counties in 2006. Formal eradication was completed last year. Monitoring, sterile moth releases and trapping continue.
“We caught 207,000 natives in traps in central Arizona in 2006; so far we have eight captures in 2010,” Antilla said. “We haven’t found a larva since 2008.”
The natives were found in the Tonopah and Harquahala areas in western Maricopa County.
Area Two eradication was kicked off in 2007 in La Paz and Mohave counties which border the Colorado River. There are no native captures or evidence of reproduction. Area Two also includes the Southern California counties of Riverside, San Bernardino and Imperial.
Areas One and Two have a 99.99 percent reduction in pinkies to date, Antilla reports. 2010 is the final year for Area Two eradication.
Area Three eradication was launched in 2008 in Yuma County. Moth captures have declined 99.4 percent.
“I hope to have no reproduction in Yuma County by the end of this year,” Antilla said. “Year four (2011) would basically include cleaning up and maintaining maximum trapping and sterile moth releases.”
Mexico has done a good eradication job so far, Staten says. The major cotton-growing areas include the states of Chihuahua (150,000 cotton acres), Sonora (9,000 acres), and Baja California (49,000 acres). The major growing areas in Chihuahua include Ascension, Ojinaga, Delicias and Juárez. San Luis is the top cotton area in Sonora. Major production in Baja is centered in Mexicali.
“We have not found a single larva in the state of Chihuahua for three years,” Staten said.
Achieving eradication of the pink bollworm in desert cotton is at arm’s length.
“It’s essential that each of the multiple organizations involved in pink bollworm eradication stay on track,” Antilla said. “That’s what it will take to finish the job.”