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Pink bollworm on the cusp of eradication in Desert Southwest

When entomologist Bob Staten began his career at USDA, his first assignment was researching pink bollworm (PBW) control in cotton in Southern California's Coachella Valley.

It was a challenging beginning. The PBW population was so overwhelming Staten said controlling the worm pest was like “riding a tricycle trying to catch a freight train.” There were untreated cotton fields in Coachella where the pest lived up to its dubious reputation as the world's most destructive cotton pest by leaving nothing to harvest in untreated cotton.

This was in the early stages of a Desert Southwest war against PBW that has lasted for more than three decades.

Staten went on to become the entomologist many consider the No. 1 worldwide authority on PBW. His tricycle now is tantalizingly close to catching that locomotive.

Staten and many others who have warred against the tiny pink worm that destroys cotton bolls believe that the insect will be eradicated from the Desert Southwest states of Texas, New Mexico, Arizona and California, plus northern Mexico before the end of this decade.

“We are gong to get the job done,” proclaimed Roll, Ariz., cotton producer Clyde Sharp who, along with many other cotton industry leaders in Arizona, has spent the past three years convincing other Arizona growers that pink bollworm can be driven out of the state and then getting federal funds and EPA approval to do it.

Arizona and Imperial and Riverside counties in Southern California represent the final frontier of this eradication effort that began four years ago in Far West Texas and New Mexico.

Sharp is confident in another four years the insect that has dictated the production of desert cotton for 40 years will be driven 1,000 miles into the interior of Mexico.

The insect pest that has only cotton as a viable host was once “controlled” by repeated aerial applications of pesticides that resulted in many cotton growers becoming ex-cotton producers. PBW is a key reason cotton is no longer in Coachella Valley and the chief culprit in cotton acreage plummeting from 100,000 acres in Imperial Valley to less than 5,000 acres today. Although urbanization had a lot to do with Arizona's acreage dropping by 400,000 acres in recent years, the cost of controlling PBW had a lot to do with it as well.

PBW eradication for the surviving desert cotton growers is likely not with the use of pesticides, but with a combination of amazing technology: pheromone mating confusion, sterile insect releases to overwhelm native populations and insect-resistant biotech Bt cotton.

Staten, who retired recently from USDA but remains a consultant to the eradication effort, said when the pink bollworm is declared economically eradicated, it will be the “next greatest success in cotton pest control since boll weevil eradication.”

Arizona growers approved an eradication effort in 2004, but has been unable to start the eradication effort until now due to a lack of federal funding. They were seeking $7.8 million; hoping for $6 million and ended up with $5.3 million for the first year.

This money is targeted primarily for producing sterile pink bollworm moths at the sterile moth rearing facility in Phoenix, Ariz., and financed by California cotton growers for its long running, successful PBW sterile release program.

The one-of-a-kind 69,000-square-foot facility is now producing 22 million sterile PBW moths per day for aerial distribution to New Mexico, Texas and northern Mexico (10 million); Arizona (10 million) and California's San Joaquin Valley (2 million). Sterile moth technology is aerially releasing lab-reared moths sterilized with low doses of radiation to mate with fertile native moths, resulting in no viable eggs from the native moths. This same technology was used to rid the United States of screwworm in the 1960s and 1970s.

The ability to produce that many moths per day in the facility built by California cotton growers to support their exclusion is one reason PBW eradication is a realistic goal.

The rearing facility was built 12 years ago to replace a makeshift facility capable of producing only about 2.5 million moths per day.

Wally Shropshire of Blythe, Calif., chairman of the California Cotton Pest Control Board, said SJV growers anticipated a need for seven to eight million sterile moths per day back then when there were more than 1 million acres of cotton in the valley and that is why they invested in the new rearing facility. However, acreage has fallen and so has the need for sterile moths.

In hindsight, the decision to build the facility in a Phoenix industrial park was a serendipitous one because without the ability to economically produce the 22 million moths per day, eradication of the pest in the Desert Southwest would not be feasible.

However, sterile moth releases are only one leg of the three-legged eradication package. Bt or Bollgard cotton is another.

“I knew eradication could be done once we got Bt cotton,” said Sharp, who extended his term as president of Arizona Cotton Growers Association to lead the battle to get federal funds for the moths and to win EPA approval for growers to plant 100 percent Bt cotton as part of the eradication program.

Graham County, Ariz., producer Dennis Palmer agrees. Palmer is president of the Arizona Cotton Research and Protection Council, the organization directing the Arizona eradication effort.

“Bt is the key to making the program work,” he said.

Bt cotton has dramatically reduced PBW overwintering populations, according to Staten, and this means each growing season begins with a lower overall population that can now be reduced economically with pheromone mating and sterile release technology.

PBW, according to scientists, is more susceptible to the Bt in Bollgard cotton than many other worm pests. Palmer said Bt cotton alone has reduced populations to levels growers are now switching back to non-Bt cotton varieties, even before eradication is accomplished.

“From the very beginning, we were fearful of eventual resistance to Bt cotton. Just the opposite has happened. Bt cotton remains very effective against pink bollworm,” said Palmer. It has been a decade since Bt cotton was introduced into Arizona.

“I was at a meeting after the ‘05 season and I asked growers in the room if anyone had seen a pink bollworm last season. Scouts had seen pinkies, but no grower had,” said Palmer.

Make no mistake, pink bollworms are still in non-Bt cotton in huge numbers. Shropshire said recent PBW pheromone trap counts from the Palo Verde and Imperial Valley, where 90 percent of the cotton is transgenic recorded 10,000 native moths in a one-week period in early May.

Staten and others have long believed eradication is possible because cotton is the pinkie's only host. Staten, based on trials in the 1990s in Parker Valley in western Arizona, is convinced pheromones and steriles could eradicate pinkies. Bt cotton simply makes it more economical.

Several Arizona growers were also convinced eradication was possible and in 1998, tried to get a grower referendum approved in Arizona to start eradication. However, it failed.

The issue resurfaced three years ago after a pink bollworm eradication effort in Far West Texas and New Mexico started showing remarkable success.

“I think when our growers saw the big picture of what was happening in Texas, they embraced the idea of eradication,” said Palmer.

Four years ago, far West Texas growers approved a joint boll weevil/pink bollworm eradication.

“Growers there did not have a boll weevil problem yet, but key growers there knew if they could nail the weevil before it became a problem and then move into a pink bollworm eradication program they could take care of two problems at once,” said Staten.

For the past three years, growers there and in New Mexico have used Bt cotton and pheromones to reduce PBW populations to levels that sterile moths are now being dropped to bring about the demise of the pinkie as a pest.

“There has never been more than about 50 percent Bt cotton in that area during this program,” yet the eradication effort has been successful, noted Staten. “There is also a lot of Pima cotton in that area and there is obviously no Bt cotton.

“The grower community in that area has been extremely pleased with the pink bollworm eradication effort, and I think that convinced a lot of Arizona growers that eradication is possible.”

Another issue that pushed Arizona growers to approve eradication was Mexico agreeing to join the endeavor.

Texas, New Mexico, Arizona and Southern California cotton growers share an international border with Northern Mexico cotton producers. Pink bollworm is no respecter of that border and the federal government could not build a fence high enough to keep pinkie from crossing from Mexico into U.S. cotton.

Until recently, Mexico expressed little interest in any joint eradication effort, and Bt cotton was not part of their production practices. Staten said that has all changed.

The entomologist met with scientists and growers in the state of Chihuahua several years ago and detailed the researched effectiveness of Bt cotton, sterile moths and pheromone technology in many locations in the United States and Mexico.

After that, Mexico made a complete turnaround and went from a stumbling block for eradication to a leader in the eradication movement. Part of the 10 million sterile moths shipped daily from Phoenix to El Paso, Texas, are dropped in Mexico.

“It has been amazing the change we have seen and the cooperation level now in Mexico. Eighty to 90 percent of growers in Chihuahua support the effort,” said Staten. “They are incredibly dedicated to this effort.”

Shropshire is optimistic that the Mexicali Valley across from Imperial Valley, California also will come on board when the eradication effort is scheduled to move into the Arizona counties along the Colorado River and into Riverside and Imperial Valley in 2007.

The goal of this eradication effort is “to get where the San Joaquin Valley is now,” said Palmer. For almost 40 years, SJV cotton producers have kept PBW from becoming an economic pests using trap monitoring and sterile moth releases. This has been a remarkable biological control program since a major pink bollworm population has been about less than 300 miles away for four decades. Each year, native pink bollworm moths are trapped in the desert areas between Riverside County and Kern County in the southern end of the San Joaquin Valley, but the pest has never become an established cotton pest in the valley.

SJV growers are convinced the grower-funded SJV sterile moth program has save them millions in pesticide costs.

Duplicating in the desert what has been ongoing in San Joaquin has never been an economical option until now with the combination of Bt cotton, sterile moth releases and pheromones. When PBW first became an economic pest in Arizona, populations reached huge levels quickly and there was little chance of significantly reducing desert population with steriles or pheromones because there are several more generations per year in the desert than in the San Joaquin Valley.

“Now I think it is going to happen,” said Palmer. “There has been great success in New Mexico and Texas and we are confident Arizona will get to where we want to be.”

Palmer, Shropshire and Sharp all said it has taken years of work on many fronts to reach this eradication threshold. They cited the National Pink Bollworm Action Committee, a group orchestrated from the National Cotton Council; grower groups in Texas, New Mexico, Arizona and California; CDFA's pink bollworm program team and entomologists at USDA and the University of Arizona.

The last major hurdle, federal funding for sterile moths for Arizona and EPA approval for growers to plant 100 percent Bt cotton took almost three years for Sharp and other leaders of the Arizona cotton industry to accomplish.

“I learned a lot from the process we went through. You have got to get on a plane and go to Washington and get in people's faces there to get what you want,” said Sharp.

Sharp said Rick Lavis, executive director of the Arizona Cotton Growers Association, and Larry Antilla, director of Arizona Cotton Research and Protection Council, were invaluable in the process.

“Rick is a former lobbyist and he has done a lot to open doors, but congressmen and the EPA want to listen to growers.

“The message from the process we went through to start the eradication program in Arizona is as farmers we have to be prepared to tell people in government what we need and why,” he said.

Frustrating at times and always time consuming, Sharp said it was nevertheless “something I really enjoyed doing.”

Although he no longer is Growers Association president, he asked to go on the research and protection council to see the program through. He is also part of an oversight committee made up of four producers from the four states involved in eradication efforts.

Sharp explained that Arizona's cotton industry has struggled mightily over the years in overcoming boll weevil and whitefly and now are trying to get past pink bollworm. Many growers went out of business due to costs to control these pests.

Arizona production is less than 300,000 acres, however, defeating PBW would reduce costs for remaining Arizona producers and keep a viable cotton industry in the state.

It also may breathe some new life into cotton production by bringing Pima back to Central Arizona. California now produces more than 90 percent of the Pima cotton in the United States, taking that distinction away from Arizona when yields there dropped and costs went up, partly due to pink bollworm control. There is no Bt Pima cotton.

There are only three Pima roller gins left in the state; one in Central Arizona; one in Yuma and another in Safford.

“There are several ex-Pima growers in Central Arizona who have put in 30, 40 or 50 acres of Pima this year, since the eradication program is taking care of the pinkies this season. If eradication works, Arizona might be back in the Pima business,” Sharp said.

Successfully eradicating pinkie also will allow producers to grow less expensive non-transgenic cotton and afford the opportunity for growers to be target-specific for other insect pests and preserving beneficial insects.

This the first year of the eradication effort and Maricopa, Pinal, Pima, Graham, Cochise and Greenlee counties in Central and Eastern Arizona are in the program.

Next year it will move into the Colorado River counties of Yuma, La Paz and Mohave.

Growers have two options to participate; plant 100 percent Bt cotton and there will be no per acre assessment for eradication. Growers pay only the Bt tech fee. Growers opting to grow non-Bt cotton are assessed at $32 per acre for season-long PBW control using sterile moths and pheromones.

And, Sharp points out it, is a four-year program. “When we went to the growers and asked everyone to support this we said the eradication program will end after four years and it will,” Sharp said.

The only roadblock ahead is that Congress must continue to fund the program annually for three more years. After battling for two years to get the money to start the program, Sharp takes nothing for granted.

“We are going to get it done,” he repeated.

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