RESISTANCE OF APHIS-GOSSYPII (HOMOPTERA, APHIDIDAE) TO INSECTICIDES IN HAWAII - SPATIAL PATTERNS AND RELATION TO INSECTICIDE USE

For 16 populations of the cotton aphid, Aphis gossypii Glover, from Ha waii, comparisons of LC50s showed up to 3.6-fold resistance to endosul fan (an organochlorine), 390-fold resistance to esfenvalerate (a pyret hroid), 9.2-fold resistance to methomyl (a carbamate), and >2,000-fold resistance to oxydemeton-methyl (an organophosphate). Analysis of var iance showed significant intra-island variation in susceptibility to e ach insecticide. Variation among islands was significant only for endo sulfan. Total numbers of annual insecticide sprays per site ranged fro m 0 to 102. LC50s for endosulfan were positively correlated with the p revious use of endosulfan; LC50s for oxydemeton-methyl were positively correlated with the previous use of organophosphates. Results suggest that variation in insecticide susceptibility was caused by local vari ations in insecticide use.