Genotypic variation of resistance to the spotted stalk borer Chilo sacchariphagus (Bojer) in sugarcane: evidence of two distinct resistance mechanisms

We carried out an assessment of the resistance status to the spotted stalk borer Chilo sacchariphagus in a sample of 32 international sugarcane clones in Reunion. Our objectives were to characterize the genotypic variability of resistance and to characterize the role of leaf and stalk resistance in the global resistance. A significant genotypic variability in the % exited tunnels and in the leaf feeding injuries confirmed the existence of two resistance mechanisms located respectively in the leaves and in the stalk. Leaf resistance and stalk resistance exhibited genotypic and phenotypic correlation with stalk tunnelling injuries. No phenotypic or genotypic correlations were observed between leaf resistance and stalk resistance. Both resistances contributed independently to the global resistance quantified by the stalk tunnelling. The resistance status of the two main cultivars cultivated in Reunion was assessed within our germplasm sample: 'R 570' was one of the most resistant clones and 'R 579' proved to be moderately susceptible.