Potentiation of a propargite and fenpyroximate mixture against two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae).

Using susceptible and resistant reference strains and standard bioassay methods a new miticide product was screened for efficacy and cross-resistance against two-spotted spider mite, Tetranychus urticae Koch. Experimental product NN1 850.0 EW (fenpyroximate and propargite 3:10 ratio) was significantly (P<0.05) more toxic than either compound tested alone (co-toxicity index 1029). Non-overlapping 95% CIs at the LC50 and LC99 level suggest that there is no cross-resistance to NN1 850.0 EW from existing organophosphate and pyrethroid resistance. NN1 850.0 EW is worthy of further development for T. urticae control.