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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Low temperature affects cattle tick reproduction but does not lead to transovarial transmission of Anaplasma marginale

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Author(s):
Esteves, E. [1] ; Pohl, P. C. [1] ; Klafke, G. M. [2] ; Reck, J. [2] ; Fogaca, A. C. [1] ; Martins, J. R. [2] ; Daffre, S. [1]
Total Authors: 7
Affiliation:
[1] Univ Sao Paulo, Inst Ciencias Biomed, Dept Parasitol, BR-05508 Sao Paulo, SP - Brazil
[2] Inst Pesquisas Vet Desiderio Finamor, Eldorado Do Sul - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Veterinary Parasitology; v. 214, n. 3-4, p. 322-326, DEC 15 2015.
Web of Science Citations: 2
Abstract

Anaplasma marginate is an obligate intracellular pathogen that infects the erythrocytes of calves, causing bovine anaplasmosis. This rickettsia is biologically transmitted by several species of ticks. In tropical and subtropical regions of the world, Rhipicephalus microplus is the main vector. Due to their mobility and longevity, the adult males play an important role in the transmission of A. marginate to calves. Some studies have demonstrated that A. marginale can be intrastadially and interstadially transmitted in R. microplus, but the transovarial transmission has not been demonstrated so far. In the present study, we investigated the effects of low temperature on both the A. marginate migration from infected females to their offspring and reproductive parameters of the tick R. microplus. The larvae of R microplus fed on a calf infected with the strain Jaboticabal of A. marginate. At the end of the parasitic phase, fully engorged females were incubated at either 18 degrees C or 28 degrees C for oviposition. Although A. marginate was detected in the salivary glands of the females, demonstrating that the ticks were successfully infected, the presence of rickettsia was not detected in the offspring. However, the preoviposition period of the non-infected females maintained at 18 degrees C was longer than that of those maintained at 28 degrees C. In addition, the average weight of the mass of eggs as well as the egg production efficiency (ratio of the egg mass weight to the female weight) of the females maintained at 18 degrees C were significantly lower than those of the females incubated at 28 degrees C. There was no larval hatching from the eggs maintained exclusively at 18 degrees C, even at 65 days after female detachment. Hatching occurred only when the eggs maintained at 18 degrees C were transferred to 28 degrees C at 20 days after female detachment (18 degrees C/28 degrees C). We also verified a significantly higher larvae conversion efficiency (ratio of the larvae mass weight to the egg mass weight) in the group of females maintained exclusively at 28 degrees C compared to those from the 18 degrees C/28 degrees C group. Collectively, our results reinforce that low temperature exerts negative effects on female fertility and egg development in R. microplus, although it has no influence on A. marginale transmission to the progeny. In the field, the detrimental effects of temperatures on tick reproductive fitness lead to a reduction of tick population, which may cause a decrease in the incidence of bovine anaplasmosis. (C) 2015 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 13/26450-2 - Molecular characterization of the interactions among ticks, rickettsiae and vertebrate hosts
Grantee:Sirlei Daffre
Support Opportunities: Research Projects - Thematic Grants