Evaluation of the Natural Refuge Function for <I>Helicoverpa armigera</I> (Lepidoptera: Noctuidae) within <I>Bacillus thuringiensis</I> Transgenic Cotton Growing Areas in North China

Abstract

The density of Helicoverpa armigera (Hübner) populations on Bacillus thuringiensis Berliner (Bt) transgenic cotton, corn, peanut, and soybean; differences in its development on Bt cotton and common (nontransgenic) cotton; and the potential for mating among populations from Bt cotton fields and other crop fields were investigated in the suburbs of Xinxiang City (Henan Province) and Langfang City (Hebei Province) in the southern and northern parts of north China, respectively. Although development of H. armigera on Bt cotton was much slower than on common cotton, there was a still high probability of mating between populations from Bt cotton and other sources due to the scattered emergence pattern of H. armigera adults, and overlap of the second and third generations. In a cotton and corn growing region, early and late planted corn provided suitable refugia for the third and fourth generations of H. armigera, but not for the second generation. In a cotton and soybean/ peanut mix system, noncotton crops provided a natural refugia from the second- to fourth-generation H. armigera, but function of the refuge would closely depend on the proportion of Bt cotton. Consequently, it may be necessary to compensate the original mixed cropping patterns in different areas for delaying resistance development of H. armigera to Bt cotton.

Disruption of a Cadherin Gene Associated with Resistance to Cry1Ac δ-Endotoxin of Bacillus thuringiensis in Helicoverpa armigera

“…In the United States and Australia, formal nontransgenic refugium requirements have been implemented. However, the People's Republic of China has not pursued this route, partly in the expectation that small field sizes and agronomic heterogeneity would restrain the development of resistance, at least for the polyphagous pests, and partly in acceptance of the impracticability of regulating the implementation of refugia (18,30). These factors may account for the lack of unequivocal field evidence of enhanced resistance to Bt cotton containing Cry1Ac in the People's Republic of China.…”

Environmental Impact of Genetically Modified Crops

“…Because of the complexity of managing individual fields in the same region, educating and monitoring more than 10 million farmers made the use of the refuge strategy difficult to i mplement (Ru et al, 2002;Wu and Guo, 2005). In consideration of the fact that, among others, the small farm and cotton plot sizes may allow non-cotton crops to function as refugia, China does not mandate the conventional cotton refuge strategy for insect-resistant management, as occurs in the USA and Australia (Wu et al, 2002b). A preliminary field survey of functional refuge for CBW within the Bt cotton-growing areas in North China has been conducted (Wu et al, 2002b.…”

“…In consideration of the fact that, among others, the small farm and cotton plot sizes may allow non-cotton crops to function as refugia, China does not mandate the conventional cotton refuge strategy for insect-resistant management, as occurs in the USA and Australia (Wu et al, 2002b). A preliminary field survey of functional refuge for CBW within the Bt cotton-growing areas in North China has been conducted (Wu et al, 2002b. Field trials indicate that both soybean and groundnut can supply refuges for the second and third generations of the CBW.…”

“…Therefore, the low-risk farming model is recommended in YRR. Continuous monitoring showed this strategy works well because the resistance level of the CBW is still very low in China (Wu et al, 2002cLi et al, 2004).Thus, this low-risk farming strategy has been recommended for areas where farmers exclusively grow cotton without natural refuge from other crops (Wu et al, 2002b.…”

Análise de risco para a evolução da resistência de <i>Helicoverpa armigera</i> (Lepidoptera: Noctuidae) à proteína Cry1Ac expressa pelo evento de soja MON 87701 × MON 89788 no Brasil

“…A abordagem utilizada na China é sustentada pelo alto grau de polifagia de H. armigera e pela abundância de plantas hospedeiras não-Bt, proporcionando refúgios naturais suficientes para retardar a evolução de resistência. Além da disponibilidade de plantas hospedeiras não Bt, o pequeno tamanho das propriedades na China, juntamente com a elevada mobilidade de H. armigera, são apontados como fatores que contribuem para o sucesso da estratégia de refúgio natural para H. armigera (WU; GUO; GAO, 2002;BEHERE et al, 2008).…”