Resistance in maize to Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae): an overview

Abstract

The spotted stem borer (SSB) Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) is an important pest of maize in several countries of Asia and Africa. Serious crop losses have been reported, mostly in experiments conducted under artificial infestations at experimental stations. In order to develop an economical and environmentally friendly method of pest management, a large number of maize genotypes with varying levels of resistance to SSB have been identified. In resistant germplasm, all three components of resistance, namely, nonpreference, antibiosis, and tolerance, have been identified. In Asia, various studies have been conducted to elucidate the mechanism of resistance/susceptibility in two maize genotypes, Antigua Group 1 (Resistant) and Basi Local (Susceptible), against SSB. Several biological parameters including SSB larval and pupal survival, larval and pupal weights, larval and pupal period and fecundity were adversely affected due to unknown factors in the resistant source but not in the susceptible source. An ethanolic extract of Mex 17 has also been reported to inhibit the growth and development of SSB. The studies in Africa show that ovipositional nonpreference by SSB on maize genotypes was due to the presence of trichomes and surface waxes. One genotype, ICZ-T, with trichomes on both the leaf surfaces was developed. In some studies, using regression of grain yield reduction on foliar injury due to SSB attack on two maize genotypes, namely, ICZ1-CM and ICZ2-CM, both antibiosis and tolerance were reported to be the components of resistance. In more detailed studies in Africa, nonpreference, antibiosis and tolerance types of resistance mechanisms have been reported to be operating within maize genotypes Mp704, Poza Rica 7832 and ER-29SVR. The resistance mechanisms operating within these sources have also been reported in crosses with agronomically desirable sources.