Inheritance of resistance to sorghum shoot fly, Atherigona soccata

The sorghum shoot fly, Atherigona soccata Rond. (Diptera: Muscidae), is one of the most important pests of sorghum [Sorghum bicolor (L.) Moench], and host plant resistance is an important component for the management of this pest. Most of the sorghum hybrids currently under cultivation are based on cytoplasmic male-sterility (CMS). To develop a strategy to develop sorghum hybrids with resistance to shoot fly, we studied the nature of gene action for resistance to this pest in F1 hybrids derived from shoot fly-resistant and -susceptible CMS and restorer lines. The hybrids based on shoot fly-resistant CMS and restorer lines were glossy and trichomed and had lower proportion of plants with eggs (78.5% vs. 88.4 to 93.3%) and deadhearts (40.8% vs. 60.8 to 75.3%) than the hybrids based on other cross combinations, suggesting that resistance is required in both CMS and restorer lines for obtaining shoot fly-resistant hybrids. Proportional contributions of CMS lines for oviposition, deadhearts, leaf glossiness, and recovery resistance were greater than those of the restorer lines. The general (GCA) and specific combining ability (SCA) estimates suggested that inheritance for oviposition nonpreference, deadhearts, recovery resistance, and the morphological traits associated with resistance or susceptibility to A. soccata were governed by additive-type of gene action. The SCA effects and heterosis estimates indicated that heterosis breeding would not be rewarding in breeding for resistance to shoot fly