Cytoplasmic male-sterility and source of pollen influence the expression of resistance to sorghum midge, Stenodiplosis sorghicola

Sorghum midge, Stenodiplosis ( Contarinia) sorghicola (Coquillett), is an i mportant pest of grain sorghum, and host plant resistance is an important a spect of control of this pest. This research investigated how cytoplasmic m ale-sterility and source of pollen influence the expression of resistance t o sorghum midge. Sorghum midge emergence was significantly lower in panicle s of midge-resistant and midge-susceptible cytoplasmic male-sterile lines w hen pollinated with AF 28 - a midge-resistant restorer line, than those pol linated with Swarna - a midge susceptible restorer line, indicating the pre sence of xenia effects. Maintainer lines (B-lines) of midge-resistant paren ts had significantly lower numbers of eggs and larvae than the B-lines of m idge-susceptible parents. Male-sterile lines of the both midge-resistant an d midge-susceptible lines were equally susceptible, indicating that resista nce to sorghum midge is influenced by factors in the cytoplasm of the B-lin e. These findings will have an important bearing on the production of hybri ds with resistance to insects.