RESUMO
Vertical transmission (VT) and associated manipulation of host reproduction are widely reported among prokaryotic endosymbionts. Here, we present evidence for widespread use of VT and associated sex-ratio distortion in a eukaryotic phylum. The Microspora are an unusual and diverse group of eukaryotic parasites that infect all animal phyla. Following our initial description of a microsporidian that feminizes its crustacean host, we survey the diversity and distribution of VT within the Microspora. We find that vertically transmitted microsporidia are ubiquitous in the amphipod hosts sampled and that they are also diverse, with 11 species of microsporidia detected within 16 host species. We found that infections were more common in females than males, suggesting that host sex-ratio distortion occurs in five out of eight parasite species tested. Phylogenetic reconstruction demonstrates that VT occurs in all major lineages of the phylum Microspora and that sex-ratio distorters are found on multiple branches of the phylogenetic tree. We propose that VT is either an ancestral trait or evolves with peculiar frequency in this phylum. If the association observed here between VT and host sex-ratio distortion holds true across other host taxa, these eukaryotic parasites may join the bacterial endosymbionts in their importance as sex-ratio distorters.
Assuntos
Anfípodes/parasitologia , Microsporídios/genética , Filogenia , Diferenciação Sexual/fisiologia , Razão de Masculinidade , Animais , Sequência de Bases , Teorema de Bayes , Feminino , Interações Hospedeiro-Parasita , Masculino , Modelos Genéticos , Dados de Sequência Molecular , Análise de Sequência de DNA , Fatores Sexuais , Especificidade da EspécieRESUMO
We examined the transmission efficiency of 2 strains of Wolbachia bacteria that cause cytoplasmic incompatibility in field populations of Aedes albopictus by polymerase chain reaction assay. We found mainland and island populations throughout Thailand to be superinfected with group A and B bacteria. Of 320 Wolbachia-positive adult mosquitoes, 97.5% were infected with both groups. Single infected individuals of each Wolbachia group were encountered in nearly equal numbers. We screened 550 offspring from 80 field-collected mothers and found the transmission efficiency of group A Wolbachia to be 96.7% and that of group B Wolbachia to be 99.6%. Mothers that did not transmit both Wolbachia infections to all of their offspring were significantly larger in size than those with perfect transmission fidelity. We discuss our findings in relation to the prospects of the use of Wolbachia as a gene-driving mechanism.
Assuntos
Aedes/microbiologia , Insetos Vetores/microbiologia , Wolbachia/crescimento & desenvolvimento , Animais , DNA Bacteriano/química , DNA Bacteriano/genética , Feminino , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Tailândia , Wolbachia/genéticaRESUMO
We measured the seasonal abundance and bloodfeeding behavior of species A and C of the mosquito Anopheles minimus Theobald 1901 in an endemic malarious area of western Thailand. An. minimus s.l. is a major vector of human malarial and filarial parasites in Southeast Asia. Mosquitos were collected once a month for one year using four collection methods: human-baiting indoors, human-baiting outdoors, human-baiting in the forest, and cow-baiting. We found that both species A and C tend to feed from cows rather than humans; we did not find any preference for indoor, outdoor or forest-biting in either species. Both species had a peak biting density in October/November, at the end of the rainy season, and species C showed a second, smaller peak at the end of the cool season. These findings are discussed in relation to previous reports of the behavior of An. minimus s.l., particularly in light of suggestions that An. minimus s.l. has changed its feeding behavior in response to DDT spraying.
