SOURCES AND MECHANISMS OF RESISTANCE TO SORGHUM HEAD BUG, EURYSTYLUS-IMMACULATUS ODH IN WEST-AFRICA

Sorghum is one of the most important cereal crops in West Africa, and the head bug, Eurystylus immaculatus Odh. (Hemiptera: Miridae) is the key pest of grain sorghum in this region. A range of sorghum genotypes were evaluated for resistance to sorghum head bug at Sotuba (Mali) an d Kamboinse (Burkina Faso). Genotypes CSM 388, IS 14332, Malisor 84-7, Sakoika. S 29 and Kamboinse local were resistant to head bugs. both u nder natural and headcage screening. Head bug resistant genotypes had a lower percentage of head bug damaged grain. The food quality of head bug damaged grain was very poor and unacceptable. Cultivar non-prefer ence was identified as a component of resistance to head bugs. and CSM 388 was nonpreferred compared to E 35-1. Panicle compactness was posi tively associated with head bug numbers and grain damage. However, gen otypes with loose panicles were also susceptible to bugs. Long glumes (>5 mm), days to glume opening (>20 days after anthesis), >50% coverin g of the grain by the glumes, and grain hardness contribute towards re sistance to Eurystylus immaculatus. This information will be useful fo r developing a programme to breed for resistance to this insect in Wes t Africa.