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Pink bollworm control: greatest environmental story seldom told

Pink bollworm control: greatest environmental story seldom told

A couple of weeks back my wife and I spent a delightful and reflective evening at a retirement dinner.

The occasion was the retirement of 84-year-old Wally Shropshire of Blythe, Calif., from the California Cotton Pest Control Board. Joining the party was a pair of veteran farmers:  93-year-old Jack Stone of Kings County, Calif., and 76-year-old Richard Johnson of Chowchilla, Calif.

These three men are the last living members of the initial nine men appointed to the California Cotton Pest Control Board. This board is a grower advisory committee established by the California Department of Food and Agriculture 42 years ago to be the cotton farmer’s voice of a then fledgling program to keep the pink bollworm (PBW) out of the San Joaquin Valley.

The leadership of Wally, Jack and Richard and the other six members of that first board and a cast of literally thousands of scientists, administrators, later board members and cotton grower associations achieved what is undoubtedly one of the most significant environmental stewardship programs ever accomplished in U.S. agriculture.

The grower-funded San Joaquin Valley pink bollworm program unquestionably not only saved the San Joaquin Valley cotton industry, but spared the environment literally tons of pesticides that would not only have cost farmers millions of dollars, but could have changed the entire farming system in the San Joaquin Valley.

That is not hyperbole. Just ask Arizona and Southern California farmers. The pink bollworm was largely responsible for wiping out the 150,000-acre Imperial Valley cotton industry. It almost brought the desert cotton industry in Arizona along the California side of the Colorado River to its knees.

Songs are written about and statues erected to the boll weevil. However, by comparison, controlling and eradicating the boll weevil is child’s play compared to the pink bollworm, the most destructive cotton pest in the world. Uncontrolled, PBW moths lay eggs into cotton bolls. Larvae hatch from within and destroy the boll. Controlling PBW requires an array of expensive tools from pesticides, to pheromone monitoring and mating confusion technology and elimination of overwintering hosts. In the past decade, development of biotech cotton has represented a major breakthrough in the PBW battle. It has actually led the U.S. and Mexico to near eradication of the pink bollworm. This is something Arizona cotton growers could not fathom in the mid 1960s when the pink bollworm migrated from the Rio Grande Valley of Texas to the Sonoran Desert.

It quickly became obvious to CDFA and growers that the millions of acres of SJV cotton grown then would not likely survive the pink bollworm. It had to be stopped before it crossed the Southern California desert and established itself in Kern County, the southern most of the six SJV cotton producing counties.

PBW may have migrated west from Texas; however, the Lone Star state also gave us the technology to keep the pinkie out of the San Joaquin. Texas ranchers initiated a screwworm eradication program. You have to be at least 50 years old to understand the devastation caused by the screwworm. It feeds on live flesh and for as long as livestock have roamed the West until it was eradicated in the 1960s, animals had to be inspected and treated for the flesh eating maggots.

Screwworm lessons

I wrote many screwworm articles when I was a reporter on a couple of West Texas dailies and the Tucson (Ariz.) Daily Citizen. Some of those articles detailed health officials finding screwworms feeding on humans. It also was common in dogs and cats.

There was no way to spray insecticides over the vast expanses of the arid West to control screwworm. USDA-ARS entomologists Ed Knipling and Ray Bushland developed a sterile insect technique that exposes lab-reared screwworms to low doses of radiation to make them sterile. These sterile flies are aerially released to mate with fertile females. The result is no eggs develop. It is an amazing biological control technique.

This technology was employed to not only drive screwworm out of the U.S, but drive them all the way to the Isthmus of Panama where there is a sterile release barrier to block any re-migration north.

Scientists determined that this same technology could be utilized to keep pink bollworm out of the San Joaquin. With federal grants and grower money funding, a pink bollworm rearing facility was built in Phoenix. It was first located in trailers on property owned by Arizona cotton growers and later a permanent rearing facility funded by California cotton growers that is still in operation and the key to eradicating the pink bollworm in Arizona, New Mexico and Texas, Southern California and Northern Mexico.

Millions of pink bollworms are raised in that facility and packaged for shipment to areas where they are loaded on planes and dropped on cotton fields. This has been going on for more than four decades in the valley and now employed as part of the eradication effort.

California cotton growers are assessed annually to support this program, which includes extensive mapping of cotton fields and pheromone trapping. These traps catch both sterile and, if there are any, native moths. This is how program leaders know if the sterile moths are working. The PBW threat has never gone away in those four decades. Migrating native PBW moths have been trapped in the deserts between Southern California and the southern San Joaquin over the years.

Hot spots have been identified in the past where trap catches of native moths indicate possible infestations brewing. This triggers higher sterile moth drops in the area and possible treatment with pheromone impregnated fibers to disrupt mating of native moths.

Another key to this exclusion/control process is preventing overwintering of PBW. Cotton growers are required to shred and bury cotton residue after harvest to create a winter-long host free period. SJV growers cannot plant cotton until March 10 to maintain that host free period. Arizona growers utilize the same PBW management practice.

Arizona has survived the pink bollworm for decades, but it has been a costly fight. They started to rid themselves of the insect pest with the introduction of Bt cotton. This remarkable technology slashed pesticide and pheromone costs and opened the door to eradication.

Nightmare from the past

If all goes well with the final stages of the PBW eradication program, directed by the Arizona Cotton Research and Protection Council, pink bollworm will become a nightmare from the past.

Control and eradication of the pink bollworm is a remarkable accomplishment. I have written thousands of words on the subject since the mid-1960s when University of Arizona entomologist first started researching pheromones to monitor PBW life stages in the hopes of timing pesticides for the highest efficacy. It was called science fiction then by many growers, who said the only way to control pink bollworm was to spray cheap pesticides on weekly schedules. I also recall very contentious meetings in Imperial Valley where growers and University of California entomologists sparred over controlling pink bollworm.

There were also detractors in the San Joaquin Valley who said there was no need to fund the exclusion program. After all, the pink bollworm could never survive the cold, wet valley winters; the San Joaquin Valley was not the Arizona desert. The Cotton Pest Control Board accepted the recommendation of entomologists to erect small cages in the middle of SJV cotton fields, and introduce fertile pink bollworms into them to test that coffee shop theory. After watching three and four generations thrive in those cages, detractors faded away.

There may be some now who say with the eradication program nearing final success, there is no need to continue the program in the valley. That is nearsightedness. The need for sterile moth releases may lessen, but you can bet cotton industry leaders will continue to press for grower funding of ongoing mapping and monitoring of cotton fields.

The state-of-the-art PBW rearing facility may scale back, but it will likely remain ready to gear back up again if PBW returns or is utilized for rearing and sterilizing other pests for use in another control/eradication project. I am obviously no entomologist, but I can identify several troublesome lepidopterous pests in California who may be prime targets for a program like the PBW model.

I am reluctant to name names here for those who have played key roles in this extraordinary environmental accomplishment besides Jack, Wally and Richard. I would leave off someone in a list that would stretch for pages. However, at Wally’s insistence he asked that I point out the career-long work of Bob Staten, a 'retired' USDA-ARS entomologist who has never stopped working toward the eradication of the pink bollworm. He is still in the thick of the eradication effort.

Staten is a bohemian entomologist. He is unquestionably brilliant, unconventional, unselfish and tireless. He never wavered from his passionate scientific belief that pink bollworm can be eradicated.

Reflecting back on this story, you wonder whether a similar program could be initiated today in this era of environmental radicalism. Sadly, I think it would be very challenging. We have already experienced the scientifically irrational behavior of some to the pheromone-focused control of the light brown apple moth (LBAM) in Northern California.

Can you imagine how the nutcases would react to the idea of rearing and irradiating insects to aerially drop them to overwhelm a native pest? The radicals would likely try to place pink bollworm into the Endangered Species Act.

Boldness is what it took 40 years ago when the army of committed growers and scientists embarked on turning back the pink bollworm. It is a success story that is worthy of the highest scientific recognition.