Author
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TERAN-VARGAS, A - POSTGRADUATE INSTITUTE |
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RODRIGUEZ, J - POSTGRADUATE INSTITUTE |
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Blanco, Carlos |
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MARTINEZ-CARRILLO, J - INIFAP |
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CIBRIAN-TOVAR, J - POSTGRADUATE INSTITUTE |
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SANCHEZ-ARROYO, H - POSTGRADUATE INSTITUTE |
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RODRIGUEZ-DEL BOSQUE, L - INIFAP |
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STANLEY, D - UNI. OF NEBRASKA |
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/1/2005 Publication Date: 12/1/2005 Citation: Teran-Vargas, A.P., Rodriguez, J.C., Blanco, C.A., Martinez-Carrillo, J.L., Cibrian-Tovar, J., Sanchez-Arroyo, H., Rodriguez-Del Bosque, L.A., Stanley, D. 2005. Bollgard® cotton and resistance of the tobacco budworm (lepidoptera: noctuidae) to conventional insecticides in southern tamaulipas, mexico. Journal of Economic Entomology. 98 (6):2203-2209 Interpretive Summary: The effects of the adoption of biotechnology in different parts of the world have not been very well documented. A few studies that have been done in ‘first world’ economies have focused mainly on monetary impacts (i.e. reduced number of pesticide applications, profitability, etc.) and the effect on the agricultural landscape biodiversity (effect on non-target organisms, impact on diversity), while studies from third world economies have focused mainly on farmer’s health and societal issues. This study conducted in Mexico involves unique aspects of the effect of the introduction of biotechnology to an area. Documented extremely high insecticide resistance levels on a key cotton pest, the tobacco budworm, were obtained prior to the introduction of transgenic cotton (<1995) that expresses an insecticidal protein (Bt cotton). After the rapid adoption of this agricultural biotechnology on this area (close to its maximum potential of 96% of the cotton-planted surface), a reduced number of insecticide applications to control this pest followed. Once this selective pressure was diminished (from 12-15 applications of conventional insecticides per crop cycle in non-Bt cotton to only 1 after the adoption of this transgenic crop), the levels of susceptibility (diminution of resistance) became rapidly re-established. It is important to mention that in the 1960’s and 1995, the option of growing cotton in this region of Mexico had to abandoned due to the impossibility of controlling this pests with any insecticide. Bt cotton offers a desirable option to rapidly overcome synthetic (conventionally)-produced insecticide resistance to a region. Technical Abstract: Insecticide susceptibility in Heliothis virescens F. was obtained in 7 years (1991 – 2001) with larvae sampled from cotton in southern Tamaulipas, Mexico. Before 1996, at the time of the introduction of transgenic cotton expressing Cry1A(c) into the region, a clear trend towards resistance to certain insecticide groups, and documented control failures in the field in 1994-1995 were recorded. Type II pyrethroids cypermethrin and deltamethrin, the most widely used products in the region, demonstrated the highest shifts. Resistance ratios for these products increased up to >100x from 1991 to 1995. After 1996, the resistance levels showed the opposite trend. Other products with scant use pattern (permethrin, profenofos and endosulfan) or low tobacco budworm efficacy coupled to a high use pattern (methyl parathion), did not show this response. This clear trend towards reversal of susceptibility in type II pyrethroids can be explained partially by several factors: A) the high adoption rate of transgenic cotton in the region, from 31.2% in the beginning (1996) to near 100% legal adoption (88.5%) in 1998, has considerably curbed the use of synthetic insecticides, no-longer exerting selection pressure on this pest. B) The potential immigration to the region of susceptible tobacco budworms from cultivated and wild suitable hosts, as well as from transgenic cotton might have had a clear influence on the population as a whole. The influence that transgenic cotton has brought to this region can be more clearly seen by the drastic reduction of insecticide use to control this important pest, and as a consequence, the re-establishment of susceptibility to another type of control measure. Having both viable alternatives in place (synthetic pyrethroids and transgenic cotton) offer the grower options for control of the most troublesome lepidopterous pest of the region. Key words: Cotton, insecticide resistance, Bollgard®, pyrethroids; Heliothis virescens. |