aims of this study were to: obtain base-line data against 12 pesticides and to conduct an initial evaluation of the current resistance status of field-collected cotton aphid strains. To that end laboratory studies were required to establish base-line data for Australian cotton aphid. Susceptible strains of cotton aphid were established and breed in purpose built cages. When sufficient numbers of aphids were available they were assayed against a range of established and potential pesticides to establish base line-data. Once generated, the base-line data was used to screen a number of field-collected strains for resistance.