tick infestations did not cause suppressed immune responses to Anaplasma marginale vaccination in calves, anaplasmosis did not prevent calves from developing resistance to tick reinfestation which was accompanied by immediate hypersensitivity reactions against homologous tick extracts, Dermacentor albipictus did not seem to share common antigenic determinants with Boophilus microplus

Boophilus microplus, B. annulatus, Hereford heifers (exper.), permethrin or fenvalerate applied as sprays, both pyrethroids could provide adequate reduction in control programs however both acaricides failed to provide the necessary reduction to achieve complete elimination

Objective--To evaluate the efficacy of coumaphos, an organophosphate (OP) acaricide, at concentrations up to 2 times higher than the highest concentration required by the US Eradication Program against all stages of an OP-resistant strain of Boophilus microplusin experimentally infested cattle. Animals--16 tick-naïve 200-kg female Hereford calves. Procedure--Four groups of cattle (4 calves/group) were all infested with Boophilus ticks 3 times before treatment. Each group was treated with coumaphos as follows: group 1, at 0.165% active ingredient (AI); group 2, at 0.299% AI; group 3, at 0.566% AI; and group 4, not treated. Following treatment, ticks were collected for 21 days. Ticks collected 1 to 7, 8 to 14, and 15 to 21 days after treatment were considered adults, nymphs, and larvae, respectively, at time of treatment. Results--Overall control at 0.165, 0.299, and 0.566% AI was 52.9, 75.8, and 89.7%, respectively. Control of adults ranged from 4.3% at 0.165% AI to 73.5% at 0.566% AI. Control of nymphs ranged from 60.6% at 0.165% AI to 97.3% at 0.566% AI. Control of larvae was > 98% at all coumaphos concentrations. Conclusions and Clinical Relevance--All coumaphos concentrations failed to provide acceptable control for use in the US Eradication Program against OPresistant ticks. Treatment was least effective against adults and most effective against larvae. Even at 0.566% AI (2 times higher than required by the US Eradication Program), ticks were not eradicated, placing the United States at risk from dispersing cattle harboring viable ticks to uninfested areas.

Boophilus microplus engorged females stored at 4 C for up to 5 days and females kept at room temperature for 1 day and then at 4 C for 1 day showed no significant differences in their response to an organophosphate (dioxathion) as determined by the Drummond adult test

Babesia occultans n. sp. originally obtained from engorged female Hyalomma marginatum rufipes collected from cattle in Northern Transvaal, transmission studies in laboratory strain of ticks and splenectomized cattle, morphological, serological, and cross-immunity studies distinguished parasite as previously undescribed species highly infective for H. marginatum rufipes but of low virulence in cattle, unsuccessful attempt to transmit transovarially with Boophilus microplus

Amblyomma hebraeum, purification procedure used to obtain pure toxic components of tick eggs, characterization of toxin structure, histopathologic lesions observed in guinea pigs inoculated with egg extract or purified toxin, lesions in guinea pigs inoculated with crude egg extracts of 3 other ticks were histopathologically similar

Biocide action of Eucalyptus citriodora, Eucalyptus globulus and Eucalyptus staigeriana were studied against Boophilus microplus tick, aiming the production of an environmentally and ecologically conect and len harmpol acaricide. Essential oil emulsion of three Eucaliptus species were tested in five different concentrations against larvae and engorged female of B. microplus. Oils were submitted to gas chromatograph coupled to mass spectrometer (GC/MS) analysis looking for its composition. Citronelal is the major component of E. citriodora essential oil, being responsible for its acaricide action. The same happens with 1.8-cineole in E. globulus. In E. staigeriana, there are many substances involved in a synergic action against B. microplus. E. citriodora essential oil killed all ticks in an average concentration of 17.5% as compared to E. globulus with 15% and E. staigeriana with 12.5%. E. globulus concentrated emulsion killed all ticks in an average concentration of 9.9% and E. staigeriana in a concentration of 3.9%. Further steps will be pursued to make those essential oils to be tested under field conditions and available to the farmers, since bioacaricides has commercial appeal, allowing B. microplus control in a less aggressive way to the environment. | Realizou-se um estudo sobre a ação biocida de Eucalyptus citriodora, Eucalyptus globulus e Eucalyptus staigeriana no carrapato Boophilus microplus, buscando-se a produção de acaricidas menos agressivos ao meio ambiente. Os óleos essenciais das três espécies e os concentrados emulsionáveis de E. globulus e E. staigeriana foram testados em cinco concentrações diferentes contra larvas e fêmeas ingurgitadas de B. microplus. Os óleos foram submetidos à análise por cromatografia gasosa acoplada à espectrometria de massas (CG/EM), a fim de se investigar sua composição. O citronelal é o principal componente do óleo de E. citriodora, sendo responsável por sua ação acaricida. O mesmo ocorre com o 1,8-cineol em E. globulus. Em E. staigeriana existem várias substâncias que agem sinergicamente contra B. microplus. O óleo essencial de E. citriodora matou 100% dos carrapatos a uma concentração média de 17,5%, o de E. globulus a 15% e o de E. staigeriana a 12,5%. Os concentrados emulsionáveis de E. globulus mataram 100% dos carrapatos a uma concentração média de 9,9% e o de E. staigeriana a uma concentração de 3,9%. O desenvolvimento de produtos que possam ser testados a campo e comercializados a preços competitivos serão passos a serem seguidos. Os biocarrapaticidas têm um apelo comercial grande, permitindo controlar B. microplus de um modo menos agressivo ao meio ambiente.

<p>The experimental strategic control of the cattle-tick <em>Boophilus microplus </em>on calves (3/4 Holstein x 1/4 Zebu) from Viçosa was studied by the application of Amitraz, in five spraying done at 28 days intervals from October, 1990 to February, 1991. The stablishment of the strategic control system lead to a reduction in adult tick infestation of the animals, but it did not control the increase of the tick number on these animals when meteorological conditions for development of the ticks were satisfactory in the Spring of 1991.</p> | <p>Na microrregião de Viçosa-MG, foi testado um controle estratégico experimental do carrapato de bovinos <em>Boophilus microplus </em>em bezerros 3/4 Holandês x Zebu pela administração do Amitraz, de outubro de 1990 a fevereiro de 1991, em cinco banhos intervalados de 28 dias. O controle estratégico apresentou efeito redutor sobre o número de formas adultas de <em>Boophilus microplus </em>nos animais tratados, mas não foi suficiente para impedir que estes níveis se elevassem após o início de condições meteorológicas satisfatórias para o desenvolvimento de carrapato na primavera de 1991.</p>