title: Prevalence of a non-male-killing spiroplasma in natural populations of Drosophila hydei.
abstract: Male-killing phenotypes are found in a variety of insects and are often associated with maternally inherited endosymbiotic bacteria. In several species of Drosophila, male-killing endosymbionts of the genus Spiroplasma have been found at low frequencies (0.1 to 3%). In this study, spiroplasma infection without causing male-killing was shown to be prevalent (23 to 66%) in Japanese populations of Drosophila hydei. Molecular phylogenetic analyses showed that D. hydei was infected with a single strain of spiroplasma, which was closely related to male-killing spiroplasmas from other Drosophila species. Artificial-transfer experiments suggested that the spiroplasma genotype rather than the host genotype was responsible for the absence of the male-killing phenotype. Infection densities of the spiroplasma in the natural host, D. hydei, and in the artificial host, Drosophila melanogaster, were significantly lower than those of the male-killing spiroplasma NSRO, which was in accordance with the hypothesis that a threshold infection density is needed for the spiroplasma-induced male-killing expression.
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan. kagymad@affrc.go.jp
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kageyama
authors.forename: Hisashi
authors.initials: H
authors.lastname: Anbutsu
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Watada
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hosokawa
authors.forename: Masakazu
authors.initials: M
authors.lastname: Shimada
authors.forename: Takema
authors.initials: T
authors.lastname: Fukatsu
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000032:analysis; D004330:Drosophila / Q000382:microbiology*; D008297:Male; D010802:Phylogeny; D013149:Spiroplasma / Q000302:isolation & purification / Q000502:physiology*
chemical_list: D004269:DNA, Bacterial