Electrophysiological and Behavioural Responses of Sweetpotato Weevil, Cylas formicarius Fab. to Sweetpotato Varieties

Electrophysiological and behavioural studies coupled with field experiments were conducted to analyse the olfactory responses of sweetpotato weevil (SPW), Cylas formicarius Fab. to six varieties of sweetpotato, in order to understand how the olfactory system of the weevil distinguishes between volatiles from the susceptible and resistant varieties. Female SPW recorded significantly highest attraction (P < 0.01) towards 'Kishan' volatiles and lowest towards 'Gouri'. SPW infestation was highest in 'Kishan' (82.33%), whereas it was lowest in 'Gouri' (33.73%) at field level. A greater electrophysiological response was recorded by male and female SPW antenna to leaf and flower volatiles respectively. Males showed higher depolarization (amplitude) and lesser recovery time compared to females, particularly to leaf volatiles. The comparative study of electroantennographic analysis, olfactometry and infestation data indicated that 'Kishan' is the most susceptible variety, attracting a large number of weevils; while 'Gouri', is the resistant variety.