Polymorphism of mitochondrial DNA and distribution of cytoplasmic symbionts in the populations of two-spot ladybird beetle Adalia bipunctata

Abstract

In geographically distant populations of ladybird beetle Adalia bipunctata from Eurasia mitotypes and infection with symbiotic bacteria Spiroplasma and Rickettsia were determined. All populations examined demonstrated mtDNA polymorphism and striking differences in prevalence of bacteria (from about 50% of individuals infected with Spiroplasma in St.-Petersburg population and 50% of the Rickettsia prevalence in Kem' population to complete absence of bacteria in the population from Archangelsk). In the populations studied a total of 14 mitotypes were discovered, including two mitotypes that were remarkably different from the others in nucleotide composition. Mitotype 10, which was the most different from all the others, was found in all populations from Germany to Transbaikalia, excluding the population from Tashkent. Linkage disequilibrium between mitotype 10 and the Rickettsia infection was confirmed. Infection with the Spiroplasma bacteria was typical of the individuals with haplotype 1 and relative to it. The results obtained supported the conclusion on the association between infection with Spiroplasma and Rickettsia and certain mitotype of A. bipunctata, which was the consequence of either absence or rare horizontal transfer of symbionts and ancientness of the first contact between the bacteria and A. bipunctata ladybird beetles.