VARIATION IN CUTICULAR HYDROCARBONS AMONG STRAINS OF ANOPHELES (CELLIA) STEPHENSI LISTON POSSIBLY RELATED TO PRIOR INSECTICIDE EXPOSURE

Cuticular lipids were extracted in hexane from the females of four str ains of Anopheles stephensi and separated by capillary gas chromatogra phy. When the chromatograms produced were quantified and compared by d iscriminant analysis, compositional variations in the hydrocarbons ind icated that two of the strains, 'Russ' (originally isolated in the for mer U.S.S.R.) and 'Iraq' (from Iraq), both of which were susceptible t o DDT and malathion, could be confidently separated from 'Beech' from India and 'St Mal' from Pakistan, both of which were resistant to DDT and malathion. A high degree of hydrocarbon segregation between each o f the four strains might be associated with geographical variation. It appears that there are significant and real differences in the hydroc arbons of these strains and these may be at least partially related to genetic alterations resulting from prior insecticide exposure. Howeve r, far more analysis is required if any relationship with prior exposu re is to be confirmed.