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Resistance in Lepidopteran Pests to Bacillus thuringiensis (Bt) Plant Incorporated Protectants in the United States
Citation:
Impact/Purpose:
Lepidopteran resistance to Bacillus thuringiensis (Bt) traits of corn and cotton were published by academic scientists for the continental U.S. in 2014 for the fall armyworm (Spodoptera frugiperda), in 2016 for the corn earworm (Helicoverpa zea), and in 2017 for the western bean cutworm (Striacosta albicosta). Likewise, industry reported resistance for the southwestern corn borer (Diatraea grandiosella) in their resistance monitoring reports to the U.S. EPA in 2016. The Agency identified several risk factors that may have had the greatest impact on these resistance developments. Some of these are: (1) Lack of high dose traits; (2) use of single modes of action possible year-after-year; (3) corn seed blends in the southern U.S.; (4) poor refuge compliance for Bt corn in southern states; (5) continuous selection with same traits expressed in Bt corn and Bt cotton in a given year; (6) methodological approaches with monitoring for resistant field populations; and (7) challenges with identifying resistance using diet bioassays for non-high-dose pests. The Agency will discuss its analysis of identified risk factors underlying lepidopteran resistance development in the U.S. as well as associated scientific uncertainties. Furthermore, the Agency will discuss its analysis of methodological issues with collecting insects from the field, rearing and testing populations for resistance, and the feasibility of mitigating field resistance for Lepidopteran pests.
Description:
The Agency is seeking advice on major risk factors believed responsible for expediting lepidopteran adaptation to Bt toxins in the U.S. and associated scientific uncertainties. Furthermore, the Agency will discuss identified shortcomings of the current insect sampling methodologies, rearing and resistance testing of populations and the feasibility of successful mitigation when resistance is confirmed. In addition, the meeting serves to assess whether it is warranted scientifically to develop a resistance management plan for western bean cutworm. The overall goal of the meeting is to receive recommendations that reduce the resistance risks for lepidopteran pests, increase the longevity of currently functional Bt traits and future technologies, and improve the current insect resistance management program for lepidopteran pests of Bt corn and cotton.
URLs/Downloads:
Proposal to Improve Lepidopteran Resistance Management Bt PIPs
Meeting Minutes and Final Report (PDF, NA pp, 4103 KB, about PDF)
CHARGE QUESTIONS – LEPIDOPTERAN SAP 2018, JULY 17-20 (PDF, NA pp, 120 KB, about PDF)
Transmittal Memorandum; Background and Charge (PDF, NA pp, 80 KB, about PDF)
WHITE PAPER ON RESISTANCE IN LEPIDOPTERAN PESTS OF BACILLUS THURINGIENSIS (Bt) PLANT-INCORPORATED PROTECTANTS IN THE UNITED STATES (PDF, NA pp, 869 KB, about PDF)
Meeting Materials for the July 17-20, 2018 SAP