A headcage technique to screen sorghum for resistance to mirid head bug, Eurystylus immaculatus Odh. in West Africa

Abstract

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.