Study of the associations between symbiotic bacteria and parasitic arthropods continues to elucidate an increasingly complex suite of relationships. Sucking and chewing lice depend on symbiotic bacteria that provide essential nutrients to supplement their diet. These bacteria have now been characterized as members of a group of gamma-Proteobacteria found in a variety of insects. Other symbiotic bacteria, particularly the rickettsia-like genus Wolbachia are being reported from increasing numbers of insect taxa where their role in cytoplasmic incompatibility, parthenogenesis induction, male killing, feminization and overall sex ratio distortion has received a great deal of attention. PCR amplification of nine species of sucking and chewing lice using the wsp gene primer set determined the presence of Wolbachia. Detailed sequencing information allowed the construction of a phylogenetic tree relating the isolates from the various louse species. Sequencing also established that most of the louse species used in our study harbors two or more strains of Wolbachia. We tested the relative contributions of vertical versus horizontal transmission to the spread of Wolbachia in species of sucking (Anoplura) and chewing (Mallophaga) lice because lice have no known parasitoids. Co-occurrence of at least two symbiotic bacteria in lice therefore opens several questions regarding their role in louse reproduction and in the vector competence of various louse species.
Species 1: Phthiraptera Echinophthiridae Echinophthirius horridus (Seal lice)
Species 2: Phthiraptera Trichodectidae Eutrichophilus (Porcupine lice)
Species 3: Phthiraptera Pthiridae Pthirus pubis (pubic lice)
Keywords: Wolbachia, horizontal transmission
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