Evidence of antibiosis resistance to the spotted stemborer, Chilo partellus (Swinhoe) in a maize (Zea mays L.) population

Abstract

S2 line and S2 test-cross recurrent selection procedures were initiated to improve the resistance of a maize (Zea mays L.) population to the spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae). Thirty-five selections developed from the population were evaluated for resistance to the stemborer in western Kenya. Resistance was rated according to leaf feeding (LF), stem tunnelling (ST) and deadheart formation (DH) following artificial infestation with first-instar C. partellus. Larval establishment and growth were also assessed. The reduction in foliar damage ratings, percentage stem length tunnelled, and percentage of plants showing deadheart after one cycle of recurrent selection were 4.38 %, 74.80 % and 13.92 %, respectively. A very low larval establishment on all the selections was attributed to their resistance to C. partellus attack. Results from this study indicated low levels of larval growth and development. It is concluded that antibiosis was the type of resistance mechanism against C. partellus in the maize populations investigated and that more cycles of selection are required to significantly shift the gene frequencies for resistance.