The synergistic effect of imidacloprid and flumethrin in isolated nerve cord fibres of Spodoptera frugiperda. The low baseline spike activity is shown in (a). After the addition of 100 nM of imidacloprid spike activity increased to 58 counts per second (cps). Following washout of the imidacloprid spike activity reduced to 4 cps as shown in (c). The addition of 50 nM of flumethrin alone induced a spike activity of 5 cps (d). The combination of flumethrin and imidacloprid induced a dramatic increase of spike activity to 89 cps (e).