Inheritance of Sugarcane Borer Resistance in Sugarcane Derived from Two Measures of Insect Damage

Abstract

The sugarcane borer [Diatraea saccharalis (Fabricius)] is an important insect pest of sugarcane grown in the Americas. Environmental and economic concerns are driving these sugarcane industries to consider alternatives to insecticides for controlling damaging infestations of the borer. Breeding for resistance is a viable option; however, little is known of the inheritance of sugarcane borer resistance. The inheritance of sugarcane borer resistance in sugarcane (Saccharum spp. L.) was investigated in a field study conducted in 1990, 1992, and 1993. We measured resistance by both plant damage response ratings and mean percent internodes damaged. Seedling progeny (F1 plants generated from seed) from 21 to 27 crosses were evaluated each year. These progeny originated from a mating design with females nested within males. Parental genotypes were randomly selected for borer resistance, but were elite cultivars adapted to Louisiana. Data were collected from progeny infested with artificially introduced sugarcane borers. Narrow‐sense heritability on a single‐plot basis (36 plants measured per plot) for damage ratings and for percent damaged internodes were high and of comparable magnitude. For both traits, we detected neither dominance nor additive × year interaction; however, dominance × year interaction variance existed. The potential for genetic advance (GA) from direct selection against percent damaged internodes (GA = 33.9% of mean bored internode) was higher than that from direct selection for lower damage rating (13.5% of mean rating). The much greater resources needed to effect selection for percent bored internodes (approx. 24 times that for rating) suggested direct selection for damage rating may be more efficient. Because the traits were highly correlated and their heritabilities high, correlated gains in percent damaged internodes by direct selection for damage rating were nearly as high as direct selection for percent damaged internodes (31% indirect vs. 33.9% direct).