Approximately 22 000 hectares (5% of the total maize growing area) of transgenic maize expressing the Cry1Ab toxin from Bacillus thuringiensis (Bt maize) have been planted annually in Spain since 1998. Changes in the susceptibility to Cry1Ab of Spanish populations of the Mediterranean corn borer (MCB), Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae), and the European corn borer (ECB), Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), were assessed by annual monitoring on Bt maize fields. No increase in resistance was detected in the MCB populations from Ebro, Albacete, and Badajoz, nor in the ECB populations from Ebro and Badajoz during the period 1999-2002. The susceptibility of the MCB population from Madrid fluctuated from year to year, but a gradual trend towards higher levels of tolerance was not observed. Laboratory selection assays for eight generations yielded selected strains of MCB and ECB that were 21-and 10-fold significantly more tolerant to Cry1Ab than the corresponding unselected strains, respectively. Nevertheless, none of the fieldcollected or laboratory-selected larvae were able to survive on Bt maize. Considering these data, no consistent shifts in susceptibility were found for Spanish populations of MCB nor ECB after 5 years of Bt maize cultivation, but systematic field monitoring needs to be continued.

No abstract

No abstract

El artículo seleccionado no se encuentra disponible por ahora a texto completo por no haber sido facilitado todavía por el investigador a cargo del archivo del mismo.

The Spanish Government has established post-market environmental monitoring (PMEM) as mandatory for genetically modified (GM) crop varieties cultivated in Spain. In order to comply with this regulation, effects of Bt maize varieties derived from the event MON810 on the predatory fauna were monitored for two years in northeast and central Spain. The study was carried out with a randomized block design in maize fields of 3-4 ha on which the abundance of plant-dwelling predators and the activity-density of soil-dwelling predators in Bt vs. non-Bt near-isogenic varieties were compared. To this end, the plots were sampled by visual inspection of a certain number of plants and pitfall traps 6 or 7 times throughout two seasons. No significant differences in predator densities on plants were found between Bt and non-Bt varieties. In the pitfall traps, significant differences between the two types of maize were found only in Staphylinidae, in which trap catches in non-Bt maize were higher than in Bt maize in central Spain. Based on the statistical power of the assays, surrogate arthropods for PMEM purposes are proposed; Orius spp. and Araneae for visual sampling and Carabidae, Araneae, and Staphylinidae for pitfall trapping. The other predator groups recorded in the study, Nabis sp. and Coccinellidae in visual sampling and Dermaptera in pitfall trapping, gave very poor power results. To help to establish a standardized protocol for PMEM of genetically modified crops, the effect-detecting capacity with a power of 0.8 of each predator group is given.Additional key words: GMO; non-target arthropods; Orius spp.; Staphylinidae; Carabidae; PMEM; statistical power. Resumen Plan de Seguimiento del cultivo de maíz Bt en España: evaluación de los efectos de variedades con el evento MON810 sobre entomofauna no dianaCon el objetivo de cumplir con la legislación española que establece la obligatoriedad de un plan de seguimiento ambiental para post-comercialización (PMEM) para los cultivos modificados genéticamente, se evaluó durante dos años el efecto de variedades de maíz Bt derivadas del evento MON810 en la fauna depredadora, en el nordeste y centro de España. El estudio se realizó mediante un diseño de bloques al azar, en campos de maíz de 3-4 ha, en los cuales se comparó la abundancia/actividad de depredadores en planta y en el suelo entre variedades de maíz Bt y no-Bt. Las parcelas se muestrearon de 6 a 7 veces durante cada uno de los dos años mediante inspección visual de un número determinado de plantas y por medio de trampas de gravedad. No se observaron en general diferencias significativas en la densidad de depredadores en planta y en el suelo entre las variedades Bt y no-Bt y sólo los Staphylinidae mostraron capturas significativamente mayores en parcelas no Bt en el centro de España. En base a la potencia estadística obtenida de los análisis se proponen una serie de artrópodos indicadores para los ensayos de PMEM: Orius spp. y Araneae