Feeding behaviour of omethoate-resistant spider mites (Acari: Tetranychidae): a study using electrical penetration graphs

The feeding behaviour of omethoate-resistant and susceptible strains of the spider mites (Tetranychus cinnabarinus) on cowpea leaves was studied by electrical penetration graph (EPG). EPG waves of the mite feeding were divided to two forms, the high frequency (7.7-8.7 Hz) and low frequency waves (2.4-3.0 Hz), representing feeding and non-feeding behaviour respectively. The average duration of feeding periods was not significantly different between resistant and susceptible mites. However, the amplitudes of feeding waves were significantly greater in pesticide-resistant mites than susceptible mites.