Steinina ctenocephali (Ross) (Apicomplexa: Actinocephalidae) Infecting Cat Fleas, Ctenocephalides felis (Bouch?) (Siphonaptera: Pulicidae) in Taiwan: Biology and Implications
Date Issued
2011
Date
2011
Author(s)
莫里斯阿拉貢
Abstract
Abstract
The cat flea, Ctenocephalides felis, is a worldwide pest able to transmit pathogens of humans and animals so that billions of dollars worldwide annually are devoted to their control and/ or eradication. Gregarines are protozoan endoparasite members of the phylum Apicomplexa living in the internal cavities of marine and terrestrial invertebrate. The group is considered to be represented by species which are mostly host-specific with monoxenous life cycle. Thus, once gregarines were found in cat fleas in Taiwan we decide gain insight into the relationship. These data may represent the baseline information regarding how to use it as potential biocontrol agents against cat flea. This study therefore aims to study life history, morphology, taxonomy and molecular systematics, population dynamics and host-parasite relationship (i.e., effects) of Steinina ctenocephali (Ross) (Gregarine, Apicomplexa) isolated from cat fleas in Taiwan. Fleas were collected in Taipei Animal Shelter, by combing cats and dogs over a 3-year period. Under stereomicroscope S. ctenocephali-infected fleas were: i) dissected and S. ctenocephali’s stages, either microphotographed “in vivo”, stored for conventional DNA isolation (PCR, cloning, and sequencing), or electronic microscopy processing and ii) left alive and reared in microcells for recovery of S. ctenocephali oocysts. Sex of the infected fleas, type of host (i.e., dogs and cats), prevalence and intensity of gregarine infection were recorded. The whole life cycle of S. ctenocephali occurred exclusively in the flea’s gut. The oocysts (infective stage) can keep alive in the environment up 140 days. Once ingested by the flea larvae, sporozoites are released in the gut of flea larvae. Sporozoites then differentiate into trophozoites in the newly emerged fleas. Trophozoites are found attached firmly to gut of the flea by a cup-shaped epimerite with flattened bottom as support. A pair of trophozoites are then caudo-frontally associated, and then gametocysts are formed. Mature gametocysts release hundreds of oocyst into the gut of the flea as the starting point of the entire life cycle. Partial SSU rRNA gene of S. ctenocephali was amplified (approximately 1,778 bp) and analyzed for relationship whitin and among gregarines species. The S. ctenocephali appears to be closely related to Monocystis agilis Stein, Prismatospora evansi Ellis and Syncystis mirabilis Schneider but not in the same monophyly with Gregarina. Morphological and molecular data are in perfect agreement supporting the relocation of Gregarina ctenocephali Ross to the genus Steinina Lèger and Duboscq. Over three years study we found that S. ctenocephali was more prevalent in warm seasons than the cold one, female’s fleas were more attacked by gregarines, and fleas living on dogs are more prone to be infected with gregarines compared to those on cats. Gender and host preference were evident as female’s fleas were more vulnerable to be infected by gregarines, and fleas living on dogs invariably were found to be infected by more S. ctenocephali compared to cats. The artificial infection of S. ctenocephali on cat fleas indicated that this gregarine may not be an appropriate biocontrol agent. However, developmental time of flea was shortened when exposed to high dose of oocysts, which may represent an interesting, but previsouly undiscovered, case involving adaptative host-manipulation by S. ctenocephali.
Subjects
gregarine
cat flea
host parasite interaction
life cycle
new combination
SDGs
Type
thesis
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