title: Permethrin-induced morphological changes in oocytes of Rhipicephalus sanguineus (Acari: Ixodidae) semi-engorged females.
abstract: The permethrin, active ingredient of the Advantage(R) Max3--Bayer, has been widely used in the chemical control of ticks. These ectoparasites are one of the most important animal groups that cause serious damage to their hosts. This study evaluated the toxic effects of permethrin in oocytes of Rhipicephalus sanguineus semi-engorged females subjected to four treatments: group I (control--distilled water), group II (206 ppm of permethrin), group III (1031 ppm of permethrin) and group IV (2062 ppm of permethrin). Results demonstrated that permethrin is a potent chemical agent causing major structural changes in oocytes, such as emergence of large vacuolated cytoplasm regions, reducing the amount of yolk granules and decreasing the size of oocytes, culminating with cell death. As reported in the literature, these oocytes changes, besides affect the tick nervous system, also drastically reduce or prevent the reproduction process in females of R. sanguineus ticks subjected to this compound.
authors.affiliation: Departamento de Biologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, UNESP, Avenida 24 A, 1515, 13506-900 Rio Claro, SP CP 199, Brazil.
authors.forename: Gislaine Cristina
authors.initials: GC
authors.lastname: Roma
authors.forename: Karim Christina Scopinho
authors.initials: KC
authors.lastname: Furquim
authors.forename: Gervásio Henrique
authors.initials: GH
authors.lastname: Bechara
authors.forename: Maria Izabel
authors.initials: MI
authors.lastname: Camargo-Mathias
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000187:drug effects / Q000648:ultrastructure; D005260:Female; D007306:Insecticides / Q000032:analysis / Q000633:toxicity*; D009865:Oocytes / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure*; D026023:Permethrin / Q000032:analysis / Q000633:toxicity*; D048508:Rhipicephalus sanguineus / Q000502:physiology*; D016707:Tissue Fixation; D014617:Vacuoles / Q000187:drug effects / Q000648:ultrastructure
chemical_list: D007306:Insecticides; D026023:Permethrin