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) and Kamboinse (Burkina Faso). Genotypes CSM 388, IS 14332, Malisor 84–7, Sakoika, S 29 and Kamboinse local were resistant to head bugs, both under 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-preference was identified as a component of resistance to head bugs, and CSM 388 was nonpreferred compared to E 35–1. Panicle compactness was positively associated with head bug numbers and grain damage. However, genotypes with loose panicles were also susceptible to bugs. Long glumes (>5 mm), days to glume opening (>20 days after anthesis), >50% covering of the grain by the glumes, and grain hardness contribute towards resistance to Eurystylus immaculatus. This information will be useful for developing a programme to breed for resistance to this insect in West Africa.

A headcage technique to screen for resistance to sorghum head bug, Eurystylus immaculatus Odh. (Hemiptera: Miridae) was standardized for use in West Africa. Panicles infested at the half-anthesis to complete-anthesis stage had greater population build-up and suffered maximum grain damage, loss in grain mass, grain hardness and seed germination. Panicles with higher grain damage also showed greater severity of grain mould incidence. Maximum population build-up and grain damage was recorded in panicles infested with 20 pairs of adults. Panicles infested with 30–40 pairs of bugs generally showed a decrease in population build-up, possibly because of crowding. Head bug numbers decreased with a decrease in panicle size, while the extent of grain damage increased. To screen for resistance to head bugs, data should be recorded both on head bug numbers and grain damage. Fifty nymphs (third to fourth instar) or 40 bugs collected at random can also be used in the headcage to screen for resistance to head bugs.