Antibody and blood leukocyte response in Rhipicephalus sanguineus (Latreille, 1806) tick-infested dogs and guinea pigs

The dog is considered to be the natural host of Rhipicephalus sanguineus and is unable to develop appreciable resistance even after repeated feedings. The guinea pig develops strong resistance after one infestation with adult ticks. Antibody (IgG) titres against tick salivary gland antigens (SGAs) and blood leukocyte numbers in dogs and guinea pigs undergoing experimental R. sanguineus tick infestations were measured to detect a possible correlation with susceptibility or resistance of hosts. Since infested dogs develop an immediate hypersensitivity reaction to R. sanguineus antigens, total and anti-R. sanguineus SGA IgE levels were also measured in this host species. IgG and IgE antibody levels were determined by an enzyme-linked immunosorbent assay (ELISA) along three consecutive infestations of both hosts. Most dogs and guinea pigs displayed low IgG levels against R. sanguineus SGAs, though marked differences in individual response were observed. Although dog's total serum IgE levels increased significantly after infestations, no change in the amount of anti-salivary gland IgE was detected. Total and differential blood cell counts were determined in dogs and guinea pigs during primary and secondary infestation. In dogs, a tertiary infestation and a subsequent higher infestation level were also evaluated. Infested dogs did not display any alteration in blood leukocyte counts throughout the experiment. Guinea pigs, on the other hand, developed a significant basophilia during primary infestation which increased further during secondary infestation. These data reveal similarities and differences in the reactions of resistant and non-resistant hosts to ticks. They contribute for the understanding of such host-parasite relationships and will hopefully aid in the development of immune control of ticks. (C) 2003 Elsevier B.V. All rights reserved.

Degenerative process and cell death in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged female exposed to the acaricide permethrin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Colonização e lesão em fêmeas ingurgitadas do carrapato Rhipicephalus sanguineus causadas pelo fungo Metarhizium anisopliae

O presente trabalho teve como objetivo verificar a forma de penetração do fungo Metarhizium anisopliae [METSCH. (SOROKIN, 1883)] em carrapatos da espécie Rhipicephalus sanguineus (LATREILLE, 1806), assim como as lesões infringidas nos tecidos internos do ácaro. A forma de aderência e penetração do fungo foi estudada através da microscopia eletrônica de varredura e a ação do fungo nos tecidos internos avaliada em secções histológicas convencionais. Para observação destes eventos, realizaram-se infecções experimentais em 11 grupos de fêmeas ingurgitadas do carrapato R. sanguineus contendo 12 fêmeas ingurgitadas cada. Para tal, as fêmeas ingurgitadas foram banhadas durante 3 minutos, sob agitação manual, em suspensão com concentração 108 conídios/mL. No caso dos grupos controle o banho foi realizado apenas no veículo da suspensão. Os carrapatos foram processados para histopatologia e microscopia eletrônica em diversos tempos após a infecção, a saber: 1 e 18h, e um, dois, três, quatro, cinco, seis, sete, nove e onze dias. Observou-se que a maior parte dos conídios germinou em até 18h após a inoculação e que o fungo penetrou no ácaro através do tegumento 48h após a infecção. Após a penetração, o fungo invadiu o corpo do hospedeiro promovendo uma colonização difusa, sem preferência aparente por tecidos específicos. Dentre as lesões nos tecidos internos do ácaro, ressalta-se o rompimento da parede intestinal e vazamento do conteúdo para a hemocele. A morte do hospedeiro ocorreu entre 96 e 120h pós-infecção, e a esporulação do patógeno sobre o cadáver do ácaro iniciou-se em torno de 120 a 144h pós-infecção. Espera-se, com este trabalho, contribuir para o desenvolvimento e viabilização de técnicas de controle biológico dos carrapatos por fungos como alternativa ao uso de acaricidas.

Comparison of the external morphology of Rhipicephalus sanguineus (Latreille, 1806) (Acari : Ixodidae) ticks from Brazil and Argentina

In the present study the external morphology of semi-engorged Rhipicephalus sanguineus females ticks from Brazil and Argentina were compared by scanning electron microscopy. Many differences were detected among the R. sanguineus collected at the two localities, such as body size, shape of the genital pore, and morphology of the sensory structures. All these characteristics are fundamental for the diagnosis of species of the genus Rhipicephalus and thus indicate the need for further comparisons and, the taxonomical revision of this species of tick in the Neotropics. (c) 2005 Elsevier B.V. All rights reserved.

Morphological characterization of the ovary and oocytes vitellogenesis of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari : Ixodidae)

This study presents the morphology of the ovary, as well as the process of the vitellogenesis in oocytes of the tick Rhipicephalus sanguineus. The ovary of these individuals is of the panoistic type; therefore, it lacks nurse cells. This organ consists of a single tubular structure, continuous, and composed of a wall formed by small epithelial cells with rounded nuclei which delimit the lumen. The oocytes in the different developmental stages in this tick species were classified into five stages (I V). They remain attached to the ovary during vitellogenesis by a cellular pedicel and afterwards the mature oocytes (stage V) are released into the ovary lumen. (c) 2005 Elsevier B.V. All rights reserved.

Acaricidal activity of ethanolic extract from aerial parts of Tagetes patula L. (Asteraceae) against larvae and engorged adult females of Rhipicephalus sanguineus (Latreille, 1806)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Action of permethrin on Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged females: Morpho-physiological evaluation of salivary glands

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Copulation is necessary for the completion of a gonotrophic cycle in the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Inhibitory Action of Neem Aqueous Extract (Azadirachta indica A. Juss) on the Vitellogenesis of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) Ticks

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxic effects of permethrin in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged females

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of Ricinus communis oil esters on salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fipronil-induced cell death in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged females

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Azadirachta indica A. Juss (neem) induced morphological changes on oocytes of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) tick females

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of fipronil (active ingredient of Frontline (R)) on salivary gland cells of Rhipicephalus sanguineus females (Latreille, 1806) (Acari: Ixodidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of cytotoxic effects of fipronil on ovaries of semi-engorged Rhipicephalus sanguineus (Latreille, 1806) (Acari : Ixodidae) tick female

The ovary of the Rhipicephalus sanguineus dog tick female is structurally formed by oocytes in five different stages of development (from I to V) and attached to the gonad by the pedicel. The present study evaluated possible toxic effects of the acaricide fipronil (Frontline (R)) on ovaries of semi-engorged ticks. Sixty partially fed females of R. sanguineus tick were distributed into four groups of 15 specimens each: I - non-treated; II, III and IV - treated with 1, 5 and 10 ppm of fipronil, respectively. The acaricide induced structural changes in the oocytes of individuals of the different treated groups ranging from the presence of a few small vacuoles to cellular death. In conclusion, germinative cells of semi-engorged R. sanguineus tick female are affected by different concentrations of fipronil leading to the reduction of tick fertility. (c) 2008 Elsevier Ltd. All rights reserved.