Shoot fly (Atherigona soccata) resistance in improved grain sorghum hybrids

Abstract

Sorghum (Sorghum bicolor) is one of the most important cereal crops widely grown for food, feed, fodder, forage and fuel in the semi-arid tropics (SAT) of Asia, Africa, the Americas and Australia. Insect pests are the major biotic constraints for production and productivity of sorghum causing economic losses over US$1 billion annually in the SAT. Among insects, shoot fly (Atherigona soccata) is a major grain yield limiting factor that causes damage when sowings are delayed in rainy season. The early-sown crop escapes from shoot fly damage but the late-sown crop in most cases is affected. Shoot fly infestation is high when sorghum sowings are staggered due to erratic rainfall distribution which is common in the SAT. Agronomic practices, natural enemies, synthetic insecticides and host plant resistance have been employed for shoot fly management to minimize the losses. Early planting is not always feasible as the sowing window is short in rainfed situations and there exists a competition with other crops for sowing. Insecticide application is beyond the reach of resource-poor farmers in the SAT. Host plant resistance can play a major role in minimizing the extent of losses and is compatible with other tactics of pest management, including the use of natural enemies and chemical control. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) is the global repository of sorghum germplasm and contributed for development and refinement of interlard fish meal technique and no-choice-cage screening technique for selecting the sources of resistance against shoot fly and over the years made progress in developing shoot fly resistant lines. Heterosis for grain yield is well established in sorghum and it is possible to produce hybrid seeds easily because of availability of the cytoplasmic male-sterility (CMS) system (Stephens and Holland 1954). The seed industry is well established in Asia and hence the target materials for sorghum in Asia are hybrid parents. It helps to capitalize on the strengths of both public and private sectors for better delivery of products. The objective of this study is to identify sorghum hybrids and their parental lines with high levels of shoot fly resistance and high grain yields in recently developed material in the sorghum improvement program at ICRISAT, Patancheru, India.