Wolbachia, Spiroplasma, and Rickettsia symbiotic bacteria in aphids (Aphidoidea)

Aphids are a diverse family of crop pests. Aphids formed a complex relationship with intracellular bacteria. Depending on the region of study, the species composition of both aphids and their facultative endosymbionts varies. The aim of the work was to determine the occurrence and genetic diversity of Wolbachia, Spiroplasma and Rickettsia symbionts in aphids collected in 2018–2019 in Moscow. For these purposes, 578 aphids from 32 collection sites were tested by PCR using specific primers. At least 21 species of aphids from 14 genera and four families were identified by barcoding method, of which 11 species were infected with endosymbionts. Rickettsia was found in six species, Wolbachia in two species, Spiroplasma in one species. The presence of Rickettsia in Impatientinum asiaticum, Myzus cerasi, Hyalopterus pruni, Eucallipterus tiliae, Chaitophorus tremulae and Wolbachia in Aphis pomi and C. tremulae has been described for the first time. A double infection with Rickettsia and Spiroplasma was detected in a half of pea aphid (Acyrthosiphon pisum) individuals. For the first time was found that six species of aphids are infected with Rickettsia that are genetically different from previously known. It was first discovered that A. pomi is infected with two Wolbachia strains, one of which belongs to supergroup B and is genetically close to Wolbachia from C. tremulae. The second Wolbachia strain from A. pomi belongs to the supergroup M, recently described in aphid species. Spiroplasma, which we observed in A. pisum, is genetically close to male killing Spiroplasma from aphids, ladybirds and moths. Both maternal inheritance and horizontal transmission are the pathways for the distribution of facultative endosymbiotic bacteria in aphids

Invasive mosquito species Aedes albopictus and Aedes aegypti on the Black Sea coast of the Caucasus: genetics (COI, ITS2), Wolbachia and Dirofilaria infections

The area of invasive species Aedes albopictus and Aedes aegypti is expanding. Precise identification and understanding of the genetic diversity of invasive mosquito populations allows us to develop appropriate control methods. Endosymbiotic bacterium Wolbachia pipientis has different effects on their arthropod hosts and can influence the transmission and spread of the pathogens. The objective of the presented study was molecular-genetic identification of the Aedes mosquitoes collected in sampling sites on the Black Sea coast from 2007 to 2017; determination of genetic variability of Ae. aegypti, Ae. albopictus and their symbiotic bacteria Wolbachia; assessment of mosquitoes ability to be infected and to spread parasitic Dirofilaria. Another objective was obtaining the genetic characteristic of laboratory strain Ae. aegypti IMPITM. We investigated two markers of nuclear and mitochondrial DNA from Ae. albopictus and Ae. aegypti and compared them to DNA from Ae. cretinus and Ae. koreiсus sympatrically inhabiting the territory, as well as to one of Ae. aegypti from a laboratory line. The study of nuclear and mitochondrial DNA revealed a low level of variability in the invasive mosquitoes Ae. albopictus and Ae. aegypti collected at different collection sites and in different years. More than a half of Ae. albopictus were infected with Wolbachia, two strains of bacteria, wAlbA and wAlbB, occur in the Ae. albopictus population on the Black Sea coast. Total infection of Ae. aegypti and Ae. albopictus with dirofilariae was 1.8 %. Dirofilaria immitis was found only in mosquito abdomen, larvae of infective stage L3 were not found. D. repens larvae developed to the infective stage in the mosquitoes of both species

Polymorphism of mitochondrial COI and nuclear ribosomal ITS2 in the Culex pipiens complex and in Culex torrentium (Diptera: Culicidae)

Polymorphism of the mtDNA gene COI encoding cytochrome C oxidase subunit I was studied in the mosquitoes Culex pipiens Linnaeus, 1758 and C. torrentium Martini, 1925 from sixteen locations in Russia and in three laboratory strains of subtropical subspecies of the C. pipiens complex. Representatives of this complex are characterized by a high ecological plasticity and there are significant ecophysiological differences between its morphologically similar members. The full-size DNA sequence of the gene COI spans 1548 bp and has a total A+T content of 70.2 %. The TAA is a terminating codon in all studied representatives of the C. pipiens complex and C. torrentium. 64 variable nucleotide sites (4 %) were found, fifteen haplotypes were detected, and two heteroplasmic specimens of C. torrentium were recorded. COI haplotype diversity was low  in Wolbachia–infected populations of the C. pipiens complex. Monomorphic haplotypes were found in C. p. quinquefasciatus and C. p. pipiens f. molestus. Three haplotypes were detected for the C. p. pipiens, but these haplotypes were not population-specific. On the other hand, each of the ten studied Wolbachia-uninfected C. torrentium individuals from three different populations had unique mitochondrial haplotypes. Polymorphism of the 478-bp ITS2 nucleotide sequences was similar in infected C. p. pipiens and C. p. pipiens f. molestus and uninfected C. torrentium specimens. The ITS2 genetic distance between C. p. pipiens and C. torrentium reached 12.5 %. Possible effects of Wolbachia invasion on C. pipiens populations are discussed

Polymorphism of mitochondrial COI and nuclear ribosomal ITS2 in the Culex pipiens complex and in Culex torrentium (Diptera: Culicidae)

Polymorphism of the mtDNA gene COI encoding cytochrome C oxidase subunit I was studied in the mosquitoes Culex pipiens Linnaeus, 1758 and C. torrentium Martini, 1925 from sixteen locations in Russia and in three laboratory strains of subtropical subspecies of the C. pipiens complex. Representatives of this complex are characterized by a high ecological plasticity and there are significant ecophysiological differences between its morphologically similar members. The full-size DNA sequence of the gene COI spans 1548 bp and has a total A+T content of 70.2 %. The TAA is a terminating codon in all studied representatives of the C. pipiens complex and C. torrentium. 64 variable nucleotide sites (4 %) were found, fifteen haplotypes were detected, and two heteroplasmic specimens of C. torrentium were recorded. COI haplotype diversity was low  in Wolbachia–infected populations of the C. pipiens complex. Monomorphic haplotypes were found in C. p. quinquefasciatus and C. p. pipiens f. molestus. Three haplotypes were detected for the C. p. pipiens, but these haplotypes were not population-specific. On the other hand, each of the ten studied Wolbachia-uninfected C. torrentium individuals from three different populations had unique mitochondrial haplotypes. Polymorphism of the 478-bp ITS2 nucleotide sequences was similar in infected C. p. pipiens and C. p. pipiens f. molestus and uninfected C. torrentium specimens. The ITS2 genetic distance between C. p. pipiens and C. torrentium reached 12.5 %. Possible effects of Wolbachia invasion on C. pipiens populations are discussed