Cotton: tweaks underway in pink bollworm eradication

Continued efforts to rid cotton fields in the West and Southwest of the pesky pink bollworm (PBW) insect, Pectinophora gossypiella, are moving the industry closer to eradication, but an issue with “suspect moths” has industry leaders tweaking the process.

The PBW is the most damaging, profit-stealing pest in Arizona cotton. Wherever the pest is found, female PBW moths lay eggs on bolls. The emerging larvae damage the boll by feeding on the seed; damaging the lint in the process. The damaged boll creates a potential pathway for other insects and fungi to enter.

(For more, see: Pink bollworm control: greatest environmental story seldom told)

State-based PBW eradication programs in California, Arizona, New Mexico, and West Texas, plus northern Mexico, are working in harmony toward the ultimate goal of eradication — zero native moths.  

These efforts include increased planting of Bt (insect resistant) Upland cotton varieties, sterile moth technology, pheromone rope mating disruption placed throughout non-Bt cotton fields, and Delta insect traps for detection.

The sterile moth component is a major weapon in the war against the PBW. At the USDA-APHIS sterile moth breeding lab in Phoenix, Ariz., PBW moths are reared on a diet including red dye. The moths are irradiated to sterilize the insect’s reproductive system. 

Sterile moths are transported to drop-off sites in California, Arizona, New Mexico, West Texas, and northern Mexico as part of bi-national eradication activities. Small aircraft drop an equal mix of male and female sterile moths over cotton fields daily.

Once they reach the ground, sterile and native (non-sterile) moths attempt to breed, but fail to reproduce since one insect is sterile. Delta sticky insect traps can capture a mixture of native and sterile PBW moths.

The sterile moth component is a proven success story in reducing native moth numbers across the western Cotton Belt. For example in Yuma County, Ariz., native moth trap captures have plunged from 61,000 moths in 2007 to zero moths last year.

This year, about 14.5 million sterile moths will be released daily over the cotton-growing areas through state-conducted eradication programs.

“The ultimate goal across the region is zero native moth captures,” said Leighton Liesner, director, Arizona Cotton Research and Protection Council (ACRPC), Phoenix, Ariz.

Liesner updated growers and pest control advisers on the PBW eradication program successes and the suspect moth issue during the 2012 Southwest Agricultural Summit in Yuma, Ariz.

In cotton fields, traps containing insects are gathered weekly and sent to identification labs in each state for analysis. The insects are placed under a microscope with 70 to 100 times magnification to determine whether PBW moths are present and whether the moths are natives or steriles, based on the presence or absence of red dye.