The diversity of Wolbachia and its effects on host reproduction in a single Adalia bipunctata (Coleoptera: Coccinellidae) population

Wolbachia is a maternally inherited bacterium that causes male-killing in the aphidophagous two-spot ladybird Adalia bipunctata. Limited data on the prevalence or diversity of Wolbachia in this species are available. Wolbachia in A. bipunctata in the Moscow collection was first discovered in 1997, and the purpose of this study was to confirm the stability of symbiosis in the same locality over time. Wolbachia multilocus sequence typing was performed by sequencing six bacterial genes to explore the diversity of the Wolbachia strains. Based on the sequence analyses, Wolbachia in A. bipunctata appears to belong to two supergroups, A and B, giving rise to three distinct evolutionary lineages, which we have designated as wAbi-1, wAbi-2, and wAbi-3. One Wolbachia strain, wAbi-1, has probably been in existence - and caused male-killing in A. bipunctata - for at least 23 years. For the first time, we found Wolbachia strain wAbi-2, which do not cause male-killing in A. bipunctata. No association was found between bacterial strains and host mitochondrial haplotypes. Moreover, the phylogenetic relationships between the strains studied in the present work and previously published Wolbachia strains distributed globally among taxonomically unrelated insects corroborate the notion of bacterial horizontal transmission in insects, including A. bipunctata.