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ARS Home » Southeast Area » Stoneville, Mississippi » Southern Insect Management Research » Research » Publications at this Location » Publication #226790
Title: Resistance Allele Frequency to Bt Cotton in Field Population of Helicoverpa armigera (Hübner) Lepidoptera: Noctuidae) in China

Author
item LIU, FENGYI - NANJING AG. UNIV., CHINA
item XU, ZHIPING - NANJING AG. UNIV., CHINA
item CHANG, JUHUA - NANJING AG. UNIV., CHINA
item CHEN, JIN - NANJING AG. UNIV., CHINA
item MENG, FENGXIA - CHINA CDC, CHINA
item Zhu, Yu Cheng
item SHEN, JINLIANG - NANJING AG. UNIV., CHINA

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2008
Publication Date: 6/1/2008
Citation: Liu, F., Xu, Z., Chang, J., Chen, J., Meng, F., Zhu, Y., Shen, J. 2008. Resistance Allele Frequency to Bt Cotton in Field Population of Helicoverpa armigera (Hübner) Lepidoptera: Noctuidae) in China. Journal of Economic Entomology. 101(3):933-943

Interpretive Summary: Bt cotton has reduced the use of chemical insecticides for cotton bollworm, Helicoverpa armigera, control and improved the efficiency of the crop’s production in areas where densities of the pest are high. If the pest becomes resistant to Bt cotton, it would reduce and possibly negate the benefits from the technology. In Qiuxian County (Hebei, China), yearly increases in the pest’s damage to Bt cotton have been observed since 2001. In 2006 and 2007, an estimate of the frequency of Bt-resistance genes occurring in the pest population was obtained. Field-collected male cotton bollworms were mated with laboratory Bt-resistant females and the progeny were fed Bt cotton leaves for 5 days. The mortality and rate of growth of the progeny were recorded which helped determine which individuals were resistant to Bt-cotton. This technique, called an F1 screen, is used to determine if field-collected males carry genes that may confer resistance to Bt cotton. Our results uncovered unusually high frequencies of Bt-resistance genes in the Qiuxian County pest population. Approximately 22 percent of the field collected males had the genetic potential for producing resistant progeny if the mating occurred with similar females. Long term use of Bt sprays and broad adoption of Bt cotton may have played a role in producing the level of Bt-resistance genes that currently exist in the population.

Technical Abstract: Resistance development in target insects to Bt cotton is a main threat to the technology. An increase in the population density of Helicoverpa armigera has been observed since 2001 in Qiuxian County (Hebei, China), where Bt cotton has been planted dominantly since 1998. This region was selected in 2006 and 2007 for estimating the frequency of alleles conferring resistance to Bt cotton using the F1 screening technique. F1 offspring from each single-pair line were screened for resistance alleles based on larval growth, development, and survival on Bt cotton leaves for 5 d. Two-year results indicated that approximately 22% of field-collected males carried resistance alleles. The conservative estimate of the resistance allele frequency was 0.106 (95% CI: 0.054-0.158) for 2006, and 0.119 (95% CI: 0.064-0.174) for 2007. This is the first report of a Bt-resistance allele frequency increasing to such a high level in a field population. Long term application of Bt sprays and dominant planting of uni-toxin-producing Bt cotton may have accelerated the resistance evolution.