Documentary Support for Continuation of a Special Local Need registration in Arizona for maximized use of Bt cotton in a sanctioned Pink Bollworm Eradication Program
Prepared by L. Antilla
Pink bollworm(PBW), Pectinophora gossypiella (Saunder), is a key pest of Southwestern cotton. Detailed information relative to pink bollworm biology, ecology and population dynamics can be found in the accompanying document (Henneberry and Naranjo 1998). The National Cotton Council has estimated that pink bollworm has an annual cost to Western cotton growers of $21.6 million for prevention, control and yield loss. Cotton varieties bioengineered to produce either the Cry1Ac or Cry1 Ac and Cry2Ab2 endotoxin of Bacillus thuringiensis are extremely effective for controlling pink bollworm. A program coordinated on a regional basis has been devised to eradicate pink bollworm using intensive planting of Bt cotton coupled with pheromone mating disruption and areawide release of sterile pink bollworm moths. A Special Local Needs Registration was requested to provide Arizona growers participating in a sanctioned eradication program exemption from the refuge requirements stipulated in section 3 of the registration requirement documents of Bollgardâ (Cry1Ac) and Bollgard IIâ (Cry1Ac and Cry2Ab2) cotton. Multiple components have been implemented to counteract the development of pink bollworm resistance to Bollgardâ and Bollgard IIâ cotton varieties, the most significant of which is the required use of pink bollworm sterile insect technology (SIT) to act as a replacement for traditional non-Bt refuge. The components include:
- Annual Identification and GPS mapping of the locations of Bollgardâ (Cry1Ac, Bollgard IIâ (Cry1Ac and Cry2Ab2) and non-Bt cotton plantings to provide precise information with which to determine fields that do not satisfy the current refuge requirements and to respond to future problems, should they arise.
- All fields including those that do not meet the current Bt cotton registrations are being targeted using Sterile Insect Technology (SIT). Sterile moths on all Bt fields are released up to three times per week at a rate designed to be in excess of 20 moths/acre/day.
- Systematic monitoring of pink bollworm populations in eradication zones using pheromone traps and sampling of bolls to permit detection of resistance, should it arise.
- Systematic monitoring of resistance in moths detected in pheromone traps within eradication zones, using molecular biological methods to detect the mutations that have been shown to be associated with pink bollworm resistance to Bt cotton in Arizona.
- Statutory limitation of the duration of the eradication efforts to a maximum of four years in each zone.
- Monitoring of resistance using established methods based on collection, culturing and bioassaying of larval populations of suitable density, if and when they are found in any Bt cotton within eradication zones.
- Continuation of a multi-agency PBW working group composed of Environmental Protection Agency, ACRPC, and University of Arizona personnel, as well as grower and industry representatives, who will closely monitor all scientific and regulatory aspects of the eradication program and formulate case specific contingency plans for responding to resistance development in eradication zones.
- Primary emphasis on the use of environmentally benign pheromone methods for control of pink bollworm in non-Bt fields within eradication zones and secondary emphasis on limited use of conventional chemical insecticides.
- Lastly, an emergency response team will continue to be used. This team has been in place for nine years for immediate response to any suspected field development. It is a collaboration of ACRPC personnel under the consultation and guidance of University of Arizona resistance monitoring experts. Their task would be to verify, document, and respond with remedial action to resistance problems. To this end, the plan for remedial action proposed by the Arizona multi-agency working group and EPA is attached. This plan is the key document to be used in any case specific contingency plan should a suspected resistant population occur.
ARIZONA PINK BOLLWORM ERADICATION PROGRAM
Pink bollworm eradication in the desert southwest is possible, for three critical reasons:
1. Cotton is the only host of pink bollworm with the exception of okra, which is extremely limited. Okra is extremely limited and non-preferred.
2. Gossyplure is a very specific and highly efficient survey tool for population detection and monitoring through trapping.
3. A wide array of diverse and effective control mechanisms exists including transgenic (Bt) cotton, pheromone mating disruption, sterile insect technology, and insecticides. Additionally, mechanical control through mandated plow down actions also aids measurably in over-wintering population reduction.
A successful approach to pink bollworm eradication is based on three key components:
1. MAPPING – The location, mapping and identification as to cotton types (Bt vs. non-Bt) of all fields in the eradication zone is an essential first step in program activities. Since the goal of the program is to eliminate all sources of population development, any undetected cotton fields can result in serious consequences to the overall effectiveness of the program and is therefore not allowed.
2. TRAPPING – Population monitoring of all fields using gossyplure baited survey traps is vital to program success. Treatment or control triggers are, for the most part, based on trap captures which must be reported on at least a weekly basis to ensure program efficacy. Traps on all fields in program areas are deployed prior to the onset of fruiting structures on the cotton plant at the rate of one trap per ten acres of non-Bt cotton and one trap per field or group of contiguous small Bt fields separated only by ditches, field roads or irrigation borders (eighty acres or less). Traps are replaced on a weekly basis and counts of both sterile and native moths made and recorded by trained ID personnel. Data is then entered into an information management system for program analysis and action.
3. CONTROL –
a. Bt cotton – No augmentive control is necessary. Multi year data in Arizona has confirmed virtually no pink bollworm survival beyond second instar larval stage.
b. Pheromone Mating Disruption – High rate pheromone mating disruption systems and supplemental sprayable pheromone applications are a proven source of control. These systems have no negative environmental effects and do not generate secondary pest problems associated with overuse of conventional insecticides.
c. Sterile Moth Technology – Based on a program that has successfully prevented establishment of pink bollworm in the San Joaquin Valley of California (700,000 acres) for the past 38 years, sterile moth releases throughout the cotton growing season will interact with all other control systems to prevent the development of pink bollworm populations throughout the eradication zone. Sterile moth releases over Bt cotton also serves to replace standard refuge strategies as an alternate source of “susceptible” moths.
d. Insecticides – Limited use of insecticides labeled for pink bollworm control may be used for intermediate knockdown of pink bollworm numbers should such become excessive in concert with other control strategies listed above.
e. Cotton Plow Down – Enforced destruction of cotton stubble by growers following harvest augments all other control systems as a means of mechanical control of soil based over-wintering populations of pink bollworm.
f. ACRPC will respond with existing resources to any resistant population in Bt cotton using the remedial action plan.
The program, as briefly outlined above, must be completed (as per Arizona State Statute) in four years or less per region.
Because maximum use of Bt cotton is critical to the timely and efficacious completion of pink bollworm eradication, the accompanying information is hereby presented to address questions and issues raised in conjunction with the current Arizona Special Local Need registration in place for 2006. It is hoped that the data presented will result in the extension of the Special Local Need registrations for 2007 and beyond.
Please be advised that the map files and data submitted are the sole property of the Arizona Cotton Research and Protection Council and as such are agency confidential. They are intended for use only by EPA and it’s Scientific Advisory Panel for evaluation of the 24C in question. Distribution to or use by any organization other than EPA and it’s Scientific Advisory Panel without the express written permission of the ACRPC is prohibited.