title: The Japanese ladybirds, Coccinula crotchi and Coccinula sinensis, are infected with very closely related strains of male-killing Flavobacterium.
abstract: Male-killing is 1 of 4 known strategies that inherited parasitic endosymbionts have evolved to manipulate their host's reproduction. In early male-killing, infected male offspring are killed early in embryogenesis. Within the Insecta, male-killing bacteria have been found in a wide range of hosts. The Coccinellidae families of beetles, better known as ladybirds, are particularly prone to male-killer invasion. In samples of the coccinellid, Coccinula crotchi, from Japan, a new male-killing bacterium was revealed by phenotypic assay. Molecular genetic analysis revealed the identity to be a tetracycline-sensitive Flavobacterium that causes female-biased offspring sex ratio. Furthermore, that Flavobacterium strain was found to be closely related to the Flavobacterium causing male-killing in the congeneric Japanese coccinellid, Coccinula sinensis, which was collected from the same region. However, we found slightly different Flavobacterium strains infecting C. sinensis from regions with different environmental conditions. This may be an indication of horizontal transmission of male-killing Flavobacterium between these 2 ladybird spices. Finally, environmental conditions may affect the spread of male-killing bacteria among their hosts.
authors.affiliation: Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK; Botany Department, Faculty of Science, Cairo University, Giza, Egypt.
authors.forename: Sherif
authors.initials: S
authors.lastname: Elnagdy
authors.forename: Susan
authors.initials: S
authors.lastname: Messing
authors.forename: Michael E N
authors.initials: ME
authors.lastname: Majerus
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000382:microbiology* / Q000502:physiology; D004269:DNA, Bacterial / Q000235:genetics; D004777:Environment; D005260:Female; D005417:Flavobacterium / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D007564:Japan; D008297:Male; D010802:Phylogeny; D012744:Sex Ratio; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D004269:DNA, Bacterial; D013752:Tetracycline
keywords: Coccinula crotchi; Coccinula sinensis; Flavobacterium; endosymbionts; inherited bacteria; male-killing; sex ratio distorter