EVALUATION OF SELECTED INSECTICIDES FOR CONTROL OF DIAMONDBACK MOTH AND CABBAGE-LOOPER IN CABBAGE IN CENTRAL FLORIDA WITH OBSERVATIONS ON INSECTICIDE RESISTANCE IN THE DIAMONDBACK MOTH

A field study was conducted to evaluate selected insecticides for the control of P. xylostella and cabbage looper, Trichoplusia ni (Hubner), in cabbage, Brassica oleracea L. (Capitata group). Chlorpyrifos, endosulfan, mevinphos, and Bacillus thuringiensis subsp. kurstaki were considerably more effective at controlling P. xylostella than cypermethrin, permethrin, methomyl, and thiodicarb. Cypermethrin, permethrin, thiodicarb, and endosulfan were the most effective at controlling T. ni. Mixtures of two insecticides improved efficacy apparently due to one component controlling T. ni. and not P. xylostella and the other component controlling P. xylostella and not T. ni. Laboratory examination of selected populations from the field study indicated that poor efficacy of the pyrethroids and carbamates on P. xylostella was probably due to insecticide resistance.