Experimental modeling of the microbiota of a biocontrol population of the predatory mite Neoseiulus californicus bred on the spider mite Tetranychus urticae was carried out to both eliminate bacterial pathogens and increase the viability of the mite line. We produced an isofemale line of N. californicus BioDefence2 and a derived line with an optimized microbiota BioDefence3. The microbiota was optimized by the sequential treatment of the mite line with tetracycline to eliminate pathogenic bacteria, followed by treatment with the probiotic bacterium Bacillus subtilis to restore the viability of the mite line. The microbiotas of the BioDefence2 and BioDefence3 mite strains were compared using metagenomic 16S rRNA gene data. The metagenomic data were extracted from the hologenomes of the mite strains obtained through Oxford Nanopore long read sequencing. The bacterial species comprising the microbiotas of the original and optimized mite strains were identified. The saprophytic soil bacteria, Stenotrophomonas maltophilia, Acinetobacter johnsonii, and Enterobacter hormaechei, also known as opportunistic human pathogens, form the basis of the N. californicus microbiota. The optimization of the microbiota eliminates the intracellular bacterium Renibacterium salmoninarum, a well-known fish pathogen and the toxin-producing bacterium Clostridium botulinum. The effect of optimization of the mite microbiota on the viability of the biocontrol population of N. californicus is discussed. The results obtained may provide a basis for improving the technology of rearing N. californicus.

Neoseiulus californicus is widely used as an effective biocontrol agent of spider mites. In this study, the complete mitochondrial genome sequence of N. californicus was determined using Oxford Nanopore sequencing technology. The complete mitochondrial genome is 21,318 bp in length and contains 13 protein-coding genes, 2 ribosomal rRNA genes and 22 transfer RNA genes. Its AT content is 78.4%. All start and stop codons of the protein-coding genes are canonical, except for the missing stop codon for the cox3 gene. The control region was polymorphic in length between the sublines of N. californicus due to variable number of direct repeats. The mitogenome presented in this paper contributes to the study of the genetic structure of N. californicus biocontrol populations.

Neoseiulus californicus is an effective predatory mite for spider mites biocontrol. We sequenced and assembled the genomes of two isofemale lines of N. californicus: BioDefence and BioDefence2, derived from a biocontrol mite population, using the Oxford Nanopore long-read sequencing method. A total of 3507265 reads were obtained for the genome of the BioDefence line and 1769217 reads for the BioDefence2 line. Canu v.2.3 software was used for contig assembly. The genome of the BioDefence line was assembled as 419 contigs of 191.4 Mb in length, with a G+C content of 50.33%. The N50 is 13147 and the average coverage is 26.798. The annotation identified – 12253 genes, including 11607 protein-coding genes, 28 microsatellites, 9 families of small RNA genes, 2 families of LTR retrotransposons, 3 families of DNA transposons, 12 rRNA genes and 634 tRNA genes. The genome of line BioDefence2 was obtained using a similar procedure. Based on the contigs obtained, we assembled two new complete mitochondrial genomes of N. californicus from the BioDefence and BioDefence2 lines. We identified hypervariable regions of the genome within the mitochondrial control region that show inter-lineage variability. This study adds a new complete genome of N. californicus assembled at the contig level to the two other complete N. californicus genomes registered in GenBank and assembled at the contig level.

The genetic diversity of gamasid mite, Hoploseius oblongus Masan & Halliday, 2016, found in France, Denmark, Ukraine, and widely spread in Russia (from the Caucasus to the Arctic), is characterized. This species, known so far from the six finds in Slovakia and Poland, lives only in the hymenophore of living fruiting bodies of the bracket fungus Fomitopsis pinicola . A total of 502 living F. pinicola fruiting bodies from 62 localities were studied, and DNA barcoding of H. oblongus individuals from 28 localities in Europe, the Caucasus, and Western and Central Siberia was performed. At least 90% of the fruiting bodies of F. pinicola in the studied regions were inhabited by the H. oblongus mite. The association of F. pinicola with the H. oblongus mite was observed throughout the Western Palearctic, up to the Yenisei River valley in the east. Throughout the territory of the extensive range examined, H. oblongus is characterized by the low sequence variation of the mitochondrial COI gene BOLD fragment and is monomorphic in the nucleotide sequence of nuclear ribosomal repeat fragment. Low genetic diversity points to the relatively recent origin of the population of H. oblongus , possibly associated with the restoration of the forest belt of Northern Eurasia in the Holocene. The efficiency of H. oblongus dispersal is ensured by the phoresy of adult mites on ovipositing females of dark-winged fungus gnats (Sciaridae) in late summer and early autumn. More rarely, mites disperse on adult gall midges (Cecidomyiidae) from the tribe Brachineurini or on adults of some other small insect species from the order Diptera.

We characterized the variability of mosquitoes of the genus Aedes, subgenus Stegomyia, in the south of European Russia and in the Far East of Russia: in Primorsky krai, Khabarovsk krai, Amur oblast, and the Jewish Autonomous Oblast. We aimed to identify new invasive species of mosquitoes of the subgenus Stegomyia and to document expansion of the range of Aedes albopictus. We analyzed samples of mosquitos on the basis of a combination of mosquito identification by morphological features and DNA barcoding. We compared the variability of the Ae. albopictus invasive population of in southern Russia with the variability of Ae. albopictus population of the native range of northern Vietnam. We found further expansion of Ae. albopictus in the south of the European part of Russia, westward to the territory of the southern coast of Crimea, and northward to the city of Tikhoretsk in Krasnodar krai. We found Ae. flavopictus in Primorsky krai and Khabarovsk krai. In Amur oblast, we found Ae. galloisi. The northern and eastern borders of the range of Ae. flavopictus coincide with the isotherms of +20°C in July and –24°C in January. We found synanthropic dense populations of Ae. flavopictus and Ae. galloisi in the Russian Far East for the first time. Analysis of variability of the BOLD fragment of the mitochondrial COI gene revealed nine new mitochondrial haplotypes of Ae. galloisi and ten new haplotypes of Ae. flavopictus. The analysis of the obtained nucleotide sequences reveals the exact clustering of the haplotypes, with 100% bootstrap value, corresponding to the species Ae. flavopictus, Ae. galloisi, Ae. albopictus, and Ae. aegypti. We did not find cases of mitochondrial introgression between Ae. flavopictus and Ae. galloisi in the area of sympatric habitant of these species. Synanthropic populations of Ae. flavopictus, Ae. galloisi, and Ae. albopictus are close to monomorphism.

Using DNA identification and metabarcoding methods, the microbiome of Phytoseiidae mites has been characterized, and symbiotic and pathogenic species of microorganisms facultatively and obligately associated with Phytoseiidae mites have been identified. The microbiome of mites consists of intestinal bacteria and fungi, intracellular bacteria and microsporidia are most common in Phytoseiidae mites. As with other groups of arthropods, infection of Phytoseiidae mites with the intracellular symbiotic bacteria Wolbachia and Cardinium causes a shift in the sex ratio in favor of females in the population and cytoplasmic incompatibility between infected and uninfected mite populations of the same species. The use of intracellular symbiotic bacteria opens the possibility of obtaining biocontrol populations consisting exclusively of females that are not able to interbreed with wild representatives of their own species, which is essential to avoid the spread of pathogenic bacteria. In biocontrol populations of Phytoseiidae mites, using DNA diagnostics, pathogenic bacteria and Microsporidia have been identified, the elimination of which can increase the viability and efficiency of the use of Phytoseiidae mites in agricultural practice.

Reproductive parasitism is a specific form of symbiosis in which a microorganism alters the reproduction of the host by interfering with the mechanisms of sex development. The review considers four changes in reproduction — male killing, parthenogenesis, feminization, and cytoplasmic incompatibility — determined by cytoplasmic bacteria. The cytogenetic and molecular genetic mechanisms of interaction between partners in the symbiotic system are discussed, including the comparative analysis of molecular-genetic factors responsible for reproductive parasitism. The features of the interaction between an insect and bacteria in symbiosis with various systems for determining the sex of the host, male and female heterogamy and haplodiploidy, are considered. Studies of cytoplasmic incompatibility are of great practical importance, since they open up prospects for non-invasive engineering on natural insect populations for biocontrol.

Various biological models are used to isolate West Nile virus, but their role as a selection factor that facilitates selection of isolates with certain properties is usually not evaluated. We compared pathogenic properties of three strains of the West Nile virus obtained from one sample of virus-containing material using different models: WNV Volgograd 900m/18 (on the model of suckling mice), WNV Volgograd 900a/18 (on C6/36 cells) and WNV Volgograd 900v/18 (on Vero cells). WNV Volgograd 900m/18 strain demonstrated virulent (LD50 5×103±0.005×104 PFU, p≤0.05) and neuroinvasive properties, induced viremia and pathomorphological changes in the liver, lymph nodes, and brain of nonlinear white mice. WNV Volgograd 900v/18 strain had similar characteristics except for neuroinvasiveness. WNV Volgograd 900a/18 variant demonstrated minimum virulence (LD50 5×104±0.005×104 PFU, p≤0.05), did not cause neurological symptoms, and was not isolated from the blood of infected animals.

Pyrethroid insecticides are currently the main tool for controlling major mosquito vectors of hemorrhagic fevers—Aedes aegypti and Ae. albopictus. The widespread use of insecticides has led to the spread of insecticide resistance mutations (or kdr mutations) in mosquito populations. A population genetic study of kdr mutations provides information on changes in the genetic structure of mosquito populations as a result of anthropogenic impact and may be useful for making epidemiological prediction for the prevalence of Dengue and Chikungunya fevers. Multiplex PCR is traditionally used to identify kdr mutations in combination with sequencing of PCR fragments. We have developed a more productive method for identifying kdr mutations based on the SNP polymorphism analysis in the vgsc gene and qPCR. We identified the kdr mutation F1534C in Aedes aegypti and Ae. albopictus from the Ha Tinh province of Vietnam. In Ae. albopictus populations from Vietnam, this mutation was identified for the first time.

The harlequin ladybird Harmonia axyridis forms stable natural populations in East Asia and southern Siberia and spreading invasive populations in Europe, Africa, North America, and South America in regions with temperate and subtropical climate. The polymorphism of the mitochondrial genome control region was characterized in population samples from populations of the native range and invasive range in Europe. The division of the native range into the eastern and western groups and the closeness of the invasive population to the eastern population group were confirmed. Haplotype diversity is maximal in the population of the Harmonia axyridis eastern population group and is reduced in the invasive population. The stability of the haplotype composition of the mitochondrial gene pool in the European invasive population in the process of the invasive range expansion was demonstrated.

The species of the virilis group of Drosophila are one of the well-studied models of speciation and microevolution. A comparative analysis of variability of the marker genes for two non-recombining regions of the genome was conducted: the BOLD fragment of the mitochondrial cox1 gene and the fragment of the dynein gene in order to identify events of interspecific hybridization in 11 Drosophila species of the virilis group. We identified single events of the mitochondrial DNA transfer from Drosophila montana to Drosophila lacicola and of the Y chromosome transfer from Drosophila ezoana to Drosophila montana. The probable connection of the modern speciation process in Drosophila montana with genomic instability and interspecific hybridization in nature is discussed.

Ladybird Harmonia axyridis is a widespread polyphage and forms stable populations in East Asia and spreading invasive populations in Europe and other regions with temperate and subtropical climate. A characteristic of haplotype diversity of native and invasive populations of H. axyridis at the atp6 gene is given. The characteristic differences in the composition and quantitative ratio of mitochondrial haplotypes between the western and eastern groups of populations of the native range are revealed. The genetic structure of invasive populations is uniform across the whole range in Europe, from the Atlantic coast to the Black Sea coast of the Caucasus, which is indicative of the spread of H. axyridis invasive populations in Europe from one center. In Europe, the mitochondrial gene pool of invasive populations is formed by two major haplotypes. This mitochondrial haplotype composition remains unchanged in the process of the invasion expansion. The possible role of mixed origin of invasive populations of H. axyridis in the formation of the invasive ability is discussed.

Adalia bipunctata Linnaeus, 1758 is a classical object for studying polymorphism of natural populations. Application of genetic markers significantly increased the possibilities of analysis of natural populations of ladybirds and opened the possibility of studying ecological adaptations at the genetic level. We analyze the geographical distribution of the mitochondrial haplotypes of A. bipunctata, determined on the basis of the variability of the mitochondrial cox1 gene in the natural populations of Norway. Two new mitochondrial haplotypes of A. bipunctata are described. We observe a geographical cline in the haplotypes frequencies from south to north. The main haplotype H1 of the central Europe is gradually replaced in the north by the haplotype H7. A possible reason for the observed geographical cline is a selective advantage of beetles with haplotype H7 in areas with a northern coastal climate.

Mitochondrial DNA sequences integrated into chromosomes are a promising object for designing genetic markers for studies of phylogenesis and genomic instability. Mitochondrial genomes of D. virilis and other Drosophila species of the virilis group contain (AT)n microsatellites in the spacer region between the atp6 and cox3 genes, and this microsatellite sequence is one of the hallmarks of the virilis group. The nuclear genome of D. virilis contains many extended fragments of mitochondrial DNA, which in total are several times longer than the mitochondrial genome. These nuclear sequences of mitochondrial origin contain all types of mitochondrial sequences, including mitochondrial genes and the aforementioned microsatellite sequence. The presence of the (AT)n microsatellite allows insertion of retrotransposon Tv1, which can transpose into the (AT)n microsatellite in a site-specific manner. The Tv1 insertion into (AT)n, close to the atp6 or cox3 pseudogenes produces a unique sequence. This sequence is formed by retrotransposon Tv1 and pseudogenes atp6 or cox3. This unique sequence can be detected in the genome by a PCR-based method. We applied this method to the detection and analysis of the nucleotide variability of the pseudogenes atp6 and cox3 associated with Tv1 insertions in a D. virilis cell culture and in the genomes of four Drosophila species of the virilis group: D. virilis, D. montana, D. borealis, and D. lacicola. We discovered new events of mitochondrial sequence transfer to the nucleus in the transplanted cell culture of D. virilis, and new Tv1 insertions, having emerged during the passage of this cell line were detected in the genome of the D. virilis transplanted cell culture. We found atp6 and cox3 pseudogenes associated with insertions of retrotransposon Tv1 in the nuclear genomes of four Drosophila species from the virilis group. These chimeric sequences proved to be species-specific. The age of the Tv1 insertion into the atp6 and cox3 pseudogenes is estimated at 1.50 Ma for D. virilis, 1.31 Ma for D. lacicola, and 1.56 Ma for D. borealis. A specific situation was revealed for D. montana, in which Tv1 insertions with nearly identical 5' and 3' long terminal repeats (LTRs) were present in accessions of flies from Europe and Asia. The age of this insertion was about 300 thousand years, and the insertion was absent from the D. montana fly line from North America.