title: Effects of the avermectin analogue MK-243 on vitellogenesis and reproduction in the ixodid tick, Amblyomma hebraeum.
abstract: A dose-dependent reduction in weight of total egg mass and a slightly increased oviposition latency were observed following injection of the avermectin analogue MK-243 (4"-epi-methylamino-4"-deoxyavermectin B1) directly into the haemocoel of engorged female Amblyomma hebraeum Koch (Acari: Ixodidae). Egg laying was almost completely inhibited at 100 micrograms/kg body weight. MK-243 markedly inhibited ovary development and vitellogenesis. Ticks treated with 100 micrograms MK-243/kg also had one-tenth the haemolymph ecdysteroid concentration compared to controls 10 days post-engorgement. Thus, among its other effects on ticks, the avermectins also inhibit the process of vitellogenesis.
authors.affiliation: Department of Zoology, University of Alberta, Edmonton, Alta., Canada.
authors.forename: M D
authors.initials: MD
authors.lastname: Lunke
authors.forename: W R
authors.initials: WR
authors.lastname: Kaufman
mesh_terms: D000818:Animals; D004187:Disaccharides; D026461:Ecdysteroids; D005260:Female; D006458:Hemolymph / Q000737:chemistry; D007306:Insecticides; D007447:Invertebrate Hormones / Q000097:blood; D007559:Ivermectin / Q000031:analogs & derivatives*; D010053:Ovary / Q000187:drug effects / Q000502:physiology; D010058:Oviposition / Q000187:drug effects; D012098:Reproduction / Q000187:drug effects; D013987:Ticks / Q000502:physiology*; D014818:Vitellogenesis / Q000187:drug effects
chemical_list: D004187:Disaccharides; D026461:Ecdysteroids; D007306:Insecticides; D007447:Invertebrate Hormones; D007559:Ivermectin; C443359:emamectin