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Surface chemistry of Sorghum bicolor and its importance in feeding by Locusta migratoria
Author(s) -
WOODHEAD SUSAN
Publication year - 1983
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1111/j.1365-3032.1983.tb00367.x
Subject(s) - wax , biology , sorghum , nymph , carbon chain , insect , seedling , alkane , botany , mythimna separata , pest analysis , lepidoptera genitalia , biochemistry , agronomy , organic chemistry , chemistry , catalysis
. Seedling Sorghum bicolor cv.65D was rejected at palpation by nymphs of Locusta migratoria L. unless the surface wax was removed. The wax by itself was unpalatable, and when fractionated chromatographically into constituent chemicals its deterrent effects were attributable to the p ‐hydroxybenzal‐dehyde, n ‐alkane, and ester fractions. Analysis of these last two fractions showed that they were unusual in that the carbon chain lengths of the molecules were shorter than expected from previous literature, and it was these smaller molecules (tested as pure chemicals) that were repellent to L.migratoria. The short‐chain esters are more volatile than the ineffective longer‐chain ones, and it is proposed that the insect may detect these chemicals by short‐range olfaction and hence reject the plant before biting, thus imparting a more effective defence to the plant.