The decrease in susceptibility to Cry1Ab was expected, but the specific contributions to this resistance by MON 810 maize cannot be distinguished from cross-resistance to Cry1Ab caused by exposure to Cry1F maize. Technologies combining multiple novel insecticidal traits with no cross-resistance to the current Cry1 proteins and high activity against the same target pests should be pursued in Brazil and similar environments. © 2015 Society of Chemical Industry.

Genetically modified plants expressing insecticidal proteins from Bacillus thuringiensis (Bt) offer valuable options for managing insect pests with considerable environmental and economic benefits. Despite the benefits provided by Bt crops, the continuous expression of these insecticidal proteins imposes strong selection for resistance in target pest populations. Bt maize (Zea mays) hybrids have been successful in controlling fall armyworm (Spodoptera frugiperda), the main maize pest in Brazil since 2008; however, field-evolved resistance to the protein Cry1F has recently been reported. Therefore it is important to assess the possibility of cross-resistance between Cry1F and other Cry proteins expressed in Bt maize hybrids. In this study, an F2 screen followed by subsequent selection on MON 89034 maize was used to select an S. frugiperda strain (RR) able to survive on the Bt maize event MON 89034, which expresses the Cry1A.105 and Cry2Ab2 proteins. Field-collected insects from maize expressing the Cry1F protein (event TC1507) represented most of the positive (resistance allele-containing) (iso)families found. The RR strain showed high levels of resistance to Cry1F, which apparently also conferred high levels of cross resistance to Cry1A.105 and Cry1Ab, but had only low-level (10-fold) resistance to Cry2Ab2. Life history studies to investigate fitness costs associated with the resistance in RR strain revealed only small reductions in reproductive rate when compared to susceptible and heterozygous strains, but the RR strain produced 32.2% and 28.4% fewer females from each female relative to the SS and RS (pooled) strains, respectively. Consistent with the lack of significant resistance to Cry2Ab2, MON 89034 maize in combination with appropriate management practices continues to provide effective control of S. frugiperda in Brazil. Nevertheless, the occurrence of Cry1F resistance in S. frugiperda across Brazil, and the cross-resistance to Cry1Ab and Cry1A.105, indicates that current Cry1-based maize hybrids face a challenge in managing S. frugiperda in Brazil and highlights the importance of effective insect resistance management for these technologies.

No abstract

No abstract

The effects of viruses on grape production and must quality are not fully understood. In this study, the evaluation of the impact of different virus infections on performance of the main autochthonous grapevine varieties of Mallorca (Callet, Manto Negro and Moll) was pursued. Therefore, a large number of vines were observed in field conditions over 4 years and tested by enzyme‐linked immunosorbent assay for viruses listed by the international certification programmes. In each variety, some specific virus infections resulted to be more effective than the others in inducing losses in production. In Callet, yield (Y) reduction was over 20% in plants infected by Grapevine fanleaf virus (GFLV). In Moll, plants subject to more than one infection showed over 40% Y decrease. In Manto Negro, the most surprising results were obtained, because plants showed almost 40% Y reduction because of Grapevine leafroll‐associated virus‐1 (GLRaV‐1) infection. In addition, virus infections were linked to some must quality parameter increase in Manto Negro and Moll, but in the majority of cases it was an indirect effect, because the decrease in production parameters played a predominant role by producing an important concentration effect. However, in Manto Negro, anthocyanin content decrease was directly related to GFLV infection.