Resistance to benzoylphenyl urea insecticides in Australian populations of the sheep body louse

Abstract A laboratory bioassay based on the failure of eggs laid by diflubenzuron-treated sheep body lice Bovicola ovis (Schrank) (Phthiraptera; Trichodectidae) to produce nymphs is described. The test is capable of detecting benzoylphenyl urea-resistant populations. A susceptible discriminating dose (topical treatment of female lice with 0.10 μg diflubenzuron) suitable for screening suspect resistant populations is suggested but testing of further populations that are naive to these insect growth regulator insecticides is warranted.