Certain pesticides were tested on the pre-pupal stages of the parasitoid Orgilus lepidus Muesebeck (Hymenoptera: Braconidae) and Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) to identify those likely to be safely incorporated into IPM programmes in potato crops in Australia. Effects on pupation, emergence and mortality rates were monitored. Endosulfan, methamidophos and permethrin were identified as relatively unsuitable. Difenoconazole, imidacloprid, pirimicarb, and thiodicarb appeared unlikely to interfere with IPM. Life cycle and development; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics; Abiotic factors; Chemical factors Phthorimaea operculella (Gelechiidae); Development; Hymenopteran parasites; Orgilus lepidus; Insecticides effect on host & parasite biology; Mortality; Fertilizers and pesticides Orgilus lepidus (Braconidae); Development; Lepidopteran hosts; Phthorimaea operculella; Insecticides effect on host & parasite biology; Mortality; Fertilizers and pesticides none