RESUMEN
The ontogenetic origins of the bacteriocytes, which are cells that harbour bacterial intracellular endosymbionts in multicellular animals, are unknown. During embryonic development, a series of morphological and transcriptional changes determine the fate of distinct cell types. The ontogeny of bacteriocytes is intimately linked with the evolutionary transition of endosymbionts from an extracellular to an intracellular environment, which in turn is linked to the diet of the host insect. Here we review the evolution and development of bacteriocytes in insects. We first classify the endosymbiotic occupants of bacteriocytes, highlighting the complex challenges they pose to the host. Then, we recall the historical account of the discovery of bacteriocytes. We then summarize the molecular interactions between the endosymbiont and the host. In addition, we illustrate the genetic contexts in which the bacteriocytes develop, with examples of the genetic changes in the hosts and endosymbionts, during specific endosymbiotic associations. We finally address the evolutionary origin as well as the putative ontogenetic or developmental source of bacteriocytes in insects.
RESUMEN
An understanding on host-parasite interaction is essential for control of disease causing organisms in domestic animals. The cat flea, Ctenocephalides felis (Bouché) is the predominant flea infesting dogs and cats in Taiwan. It was collected from 933 dogs and 197 cats from Taiwan. A total of 5878 C. felis adults were recovered; 14.6% fleas were observed to harbor Steinina ctenocephali. Female fleas were more susceptible to gregarine infection than males. Further, fleas were more likely to be infected with the gregarine at high temperatures, particularly during March-July with high parasite prevalence and intensity. Fleas harboring gregarines infection were higher in dogs than cats. Our study may help in development and application of appropriate flea control measures in Taiwan.