The chemical basis of resistance of sorghum bicolor to attack by Locusta migratoria

Woodhead, S. and Bernays, E.A. (1978) The chemical basis of resistance of sorghum bicolor to attack by Locusta migratoria. Entomologia Experimentalis et Applicata, 24 (2). pp. 123-144.

[img] PDF
Restricted to ICRISAT researchers only


The resistance of young Sorghum bicolor to attack by Locusta migratoria (L.) has been investigated from a chemical standpoint. Absence of phagostimulants is not important. The release on biting of HCN from the non-deterrent cyanogenic glucoside, dhurrin, has been shown quantitatively to play an important part in the unpalatability. Correlation of feeding data with release rates of HCN showed that the increase in palatability of Sorghum did not closely correspond to the rapid fall in release of HCN as the plants aged, and when different concentrations of HCN were directly introduced into the mouthparts of Locusta using a cannula, the concentration of HCN released after the first growth stage was insufficient to account for the continued unpalatability. The effects on Locusta of other chemicals in Sorghum were monitored using a series of crude plant extracts. A lipid-soluble extract from plants at growth stage 1 and an extract of phenolic acids naturally released from the plants at stage 2 both showed deterrent effects. The individual phenolic acids were identified and all were found to occur naturally as esters with no deterrent properties. Estimates were made of the concentrations of free acids released by disruption of the plant tissues in several ways: maximum concentration occurs at growth stage 2. Bioassays showed that the deterrent effects of HCN and the phenolic acid mixture were additive and the change in palatability of the plant with increasing maturity is thus completely accounted for

Item Type: Article
Author Affiliation: Centre for Overseas Pest Research, College House, Wrights Lane, Kensington, London W8 5SJ, United Kingdom
Subjects: Plant Protection > Pesticides
Plant Protection > Pests
Divisions: Sorghum
Depositing User: Ms K Syamalamba
Date Deposited: 25 May 2012 06:23
Last Modified: 25 May 2012 06:23
Official URL:

Actions (login required)

View Item View Item