Development of insecticide resistance and cross-resistance in fenvalerate-, and cypermethrin-selected strains of Earias vittella(fab.)

First-instar Earias vittella (Fab.) larvae were selected with fenvalerate and cypermethrin for 15 successive generations in the laboratory at 28(± 1)°C. The insect developed 7.8-fold resistance to fenvalerate and no resistance to cypermethrin. The fenvalerate-selected strain developed 2800-fold and 1200-fold cross-resistance to endosulfan and carbaryl, respectively. This strain, however, did not manifest cross-resistance to the organophosphorus insecticides, quinalphos, fenitrothion, monocrotophos and malathion, or to the synthetic pyrethroid, cypermethrin. The cypermethrin-selected strain acquired 5-, 4-, and 3-fold cross-resistance to endosulfan, fenvalerate and carbaryl, respectively and no cross-resistance to the above organophosphorus insecticides.