Resistance to insect growth regulator insecticides in populations of sheep lice as assessed by a moulting disruption assay.
Low-volume, backline applications with the benzoylphenyl urea insecticides triflumuron and diflubenzuron represent in excess of 70% of treatments for the control of sheep lice, Bovicola ovis (Schrank) (Phthiraptera: Trichodectidae), in Australia. Reports of reduced effectiveness from 2003 and subsequent controlled treatment trials suggested the emergence of resistance to these compounds in B. ovis populations. A laboratory assay based on the measurement of moulting success in nymphs was developed and used to assess susceptibility to diflubenzuron and triflumuron in louse populations collected from sheep where a control failure had occurred. These tests confirmed the development of resistance to triflumuron and diflubenzuron in at least two instances, with estimated resistance ratios of 67-94X at LC(50).
James
P J
PJ
Animal Research Institute, Department of Primary Industries and Fisheries, Yeerongpilly, Queensland, Australia. peter.james@dpi.qld.gov.au
Cramp
A P
AP
Hook
S E
SE
D000818:Animals; D001549:Benzamides / Q000494:pharmacology*; D001681:Biological Assay; D004132:Diflubenzuron / Q000494:pharmacology*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology; D010373:Lice Infestations / Q000188:drug therapy / Q000662:veterinary; D018978:Molting / Q000187:drug effects*; D009758:Nymph / Q000187:drug effects; D008003:Phthiraptera / Q000187:drug effects*
D001549:Benzamides; D007306:Insecticides; C023957:triflumuron; D004132:Diflubenzuron