ACRPC leaders were surprised last year when traps at the lab for microscopic evaluation contained PBW moths apparently without red dye, the trademark of reared sterile PBWs. This suggested the insects could be background native populations.

At least one moth was found in each of the western Cotton Belt states (except New Mexico) and northern Mexico.

“Laboratory tests on live captured moths indicated the insects were sterile and could not reproduce,” Liesner said. “We do not believe it’s a background population. The suspect finds do not appear as a reproductive threat to the pink bollworm eradication program.”

So what is the culprit for the suspect moths? In short, no one knows. The culprit could be related to sterile moth technology or a host of other factors involving environmental issues including field temperatures, low or high moisture or humidity, or others.

Due to the suspect find issue, the National Cotton Council’s pink bollworm technical advisory committee has fine-tuned the sterile moth process. Other changes will enhance PBW control in the field.

The USDA rearing lab has increased by a total of 30 percent (in 10 percent increments) the amount of red dye fed to moths compared to the early days of the sterile moth program. In addition, advanced testing technology has been installed at the USDA Center for Plant Health Science and Technology lab in Phoenix to more accurately check captured moths for red dye.

USDA has also placed a second elemental marker in reared moths.

“The two marker system will provide higher diagnostic certainty to more precisely examine the moths,” Liesner said.

The ACRPC will apply additional pheromone rope in all non-Bt cotton fields in Arizona; thanks to a one-time cotton pest appropriation approved by USDA-APHIS. In Mexico, the areas of Mexicali, Baja California and San Luis, Sonora will do the same in a coordinated effort.

“There will be no out-of-pocket costs for cotton growers planting non-Bt cotton for the extra pheromone rope,” Liesner explained.

The concept of PBW eradication began in the late 1960s in California when the pest was first found in San Joaquin Valley cotton. The insect first established itself in Mexico in the early 1900s and proceeded through Texas, New Mexico, Arizona, and finally California to become a serious pest of cotton in the West and Southwest.