Date of this Version
One factor which stimulates feeding and two factors which deter feeding by the adult sweetclover weevil have been separated by preparative paper chromatography of hot water extracts of Melilotus leaves. The factors were detected with a bioassay which measures feeding by adult weevils on sweetclover root disks impregnated with the extract or fraction being tested. A feeding stimulant (Stimulant A) and a feeding deterrent (Deterrent A) were found in both the resistant species, M. infesta, and a susceptible species, M. officinalis, in approximately equal amounts. A second feeding deterrent (Deterrent B) was found only in extracts from M. infesta. All available evidence suggests that Deterrent B is the factor primarily responsible for the resistance of M. infesta to the sweeetclover weevil.