Effect of different levels of cellulose, lignin, silica and ash contents available in mid-ribs, growing points and leaf blades of sugarcane genotypes on incidence of top borer, Scirpophaga excerptalis Walker (Lepidoptera: Pyralidae)-VIII.
Variation in plant biochemistry between different varieties of the same or different species are reported to cause variation in levels of susceptibilities to certain species of insect pests. A study into the relationship between incidence of top borer (S. excerptalis) and contents of cellulose, lignin, silica and ash present in midribs, growing points and leaf blades of 30 sugarcane genotypes was therefore performed. In spite of large variation in cellulose, silica and ash contents of midribs, growing points and leaf blades, both during third and fourth brood attacks, none of these constituents exhibited any relationship with incidence of top borer. However, the presence of lignin in midribs of genotypes showed a significant negative correlation (r = 0.825 and -0.927 during third and fourth brood attacks, respectively) with top borer incidence, but not in growing points or leaf blades.