CHARACTERIZATION OF HELIOTHIS-VIRESCENS (F) RESISTANCE TO INSECTICIDES IN MISSISSIPPI IN 1992 - MULTIPLE VS CROSS-RESISTANCE

Strains of the tobacco budworm, Heliothis virescens (F.), collected in Mississippi were evaluated in bioassays to four classes of insecticid es, The temporal frequency of survival showed no cross-resistance betw een different classes of insecticides with the exception of carbamates and organophosphates. High frequencies of resistance were found to cy permethrin and endosulfan in populations from Mississippi. Significant frequencies of resistance were also shown to carbamate and organophos phorus insecticides, although resistance frequencies were lower for th ese classes of insecticides. The lack of cross-resistance indicates me tabolic resistance (where cross-resistance is likely) is not important in H. virescens. Since organophosphates and carbamates have the same target, cross-resistance between them is further evidence for target-s ite resistance as the primary resistance mechanism. The data indicate that multiple resistance may be more wide-spread than previously repor ted.