Phylogenetic Relationships Based on DNA Barcoding Among 16 Species of the Ant Genus Formica (Hymenoptera: Formicidae) from China

Comparative mitogenomic analysis provides evolutionary insights into Formica (Hymenoptera: Formicidae)

Formica is a large genus in the family Formicidae with high diversity in its distribution, morphology, and physiology. To better understand evolutionary characteristics of Formica, the complete mitochondrial genomes (mitogenomes) of two Formica species were determined and a comparative mitogenomic analysis for this genus was performed. The two newly sequenced Formica mitogenomes each included 37 typical mitochondrial genes and a large non-coding region (putative control region), as observed in other Formica mitogenomes. Base composition, gene order, codon usage, and tRNA secondary structure were well conserved among Formica species, whereas diversity in sequence size and structural characteristics was observed in control regions. We also observed several conserved motifs in the intergenic spacer regions. These conserved genomic features may be related to mitochondrial function and their highly conserved physiological constraints, while the diversity of the control regions may be associated with adaptive evolution among heterogenous habitats. A negative AT-skew value on the majority chain was presented in each of Formica mitogenomes, indicating a reversal of strand asymmetry in base composition. Strong codon usage bias was observed in Formica mitogenomes, which was predominantly determined by nucleotide composition. All 13 mitochondrial protein-coding genes of Formica species exhibited molecular signatures of purifying selection, as indicated by the ratio of non-synonymous substitutions to synonymous substitutions being less than 1 for each protein-coding gene. Phylogenetic analyses based on mitogenomic data obtained fairly consistent phylogenetic relationships, except for two Formica species that had unstable phylogenetic positions, indicating mitogenomic data are useful for constructing phylogenies of ants. Beyond characterizing two additional Formica mitogenomes, this study also provided some key evolutionary insights into Formica.

Insights into insecticide-resistance mechanisms in invasive species: Challenges and control strategies

Threatening the global community is a wide variety of potential threats, most notably invasive pest species. Invasive pest species are non-native organisms that humans have either accidentally or intentionally spread to new regions. One of the most effective and first lines of control strategies for controlling pests is the application of insecticides. These toxic chemicals are employed to get rid of pests, but they pose great risks to people, animals, and plants. Pesticides are heavily used in managing invasive pests in the current era. Due to the overuse of synthetic chemicals, numerous invasive species have already developed resistance. The resistance development is the main reason for the failure to manage the invasive species. Developing pesticide resistance management techniques necessitates a thorough understanding of the mechanisms through which insects acquire insecticide resistance. Insects use a variety of behavioral, biochemical, physiological, genetic, and metabolic methods to deal with toxic chemicals, which can lead to resistance through continuous overexpression of detoxifying enzymes. An overabundance of enzymes causes metabolic resistance, detoxifying pesticides and rendering them ineffective against pests. A key factor in the development of metabolic resistance is the amplification of certain metabolic enzymes, specifically esterases, Glutathione S-transferase, Cytochromes p450 monooxygenase, and hydrolyses. Additionally, insect guts offer unique habitats for microbial colonization, and gut bacteria may serve their hosts a variety of useful services. Most importantly, the detoxification of insecticides leads to resistance development. The complete knowledge of invasive pest species and their mechanisms of resistance development could be very helpful in coping with the challenges and effectively developing effective strategies for the control of invasive species. Integrated Pest Management is particularly effective at lowering the risk of chemical and environmental contaminants and the resulting health issues, and it may also offer the most effective ways to control insect pests.

Characterization and Phylogenetic Implication of Complete Mitochondrial Genome of the Medicinal Ant Formica sinae (Hymenoptera: Formicidae): Genomic Comparisons in Formicidae

Ants (Hymenoptera: Formicidae) are among the largest and most widespread families of terrestrial insects and are valuable to medical and ecological investigations. The mitochondrial genome has been widely used as a reliable genetic marker for species identification and phylogenetic analyses. To further understand the mitogenome-level characteristics of the congeneric Formicidae species, the complete mitogenome of Formica sinae (Hymenoptera: Formicidae) was sequenced, annotated, and compared with other 48 Formicidae species. The results showed that gene composition, content, and codon usage were conserved. The complete mitochondrial genome of F. sinae was 17,432 bp, including 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and one control region located between rrnS and trnM, which was 1,256 bp long, the longest of all sequenced species. Gene rearrangement was not detected in Formica species (Hymenoptera: Formicidae). All PCGs of F. sinae were initiated with ATN codons and terminated with the TAA codon. The overall nucleotide composition of F. sinae was AT-biased (83.51%), being 80.58% in PCGs, 86.68% in tRNAs, 87.10% in rRNAs, and 88.70% in the control region. Phylogenetic analyses indicated that each subfamily formed a strongly monophyletic group. Furthermore, F. sinae clustered with Formica fusca (Hymenoptera: Formicidae) and Formica selysi (Hymenoptera: Formicidae). This work enhances the genetic data of Formicidae and contributes to our understanding of their phylogenic relationship, evolution, and utilization.

DNA barcoding of aphid-associated ants (Hymenoptera, Formicidae) in a subtropical area of southern China

As one of the most abundant and complex groups of terrestrial insects, ants have associations with many other organismal groups, such as hemipteran insects producing honeydew. With the aim of expanding the knowledge base of ant species associated with aphids, this study analyzed mitochondrial COI barcodes of 301 ant samples for 37 aphid-associated ant species in a subtropical area of southern China. Sequence analyses revealed that the intraspecific and interspecific distances ranged from zero to 7.7%% and 0.2 to 31.7%, respectively. Three barcoding approaches - Automatic Barcode Gap Discovery, Bayesian Poisson Tree Processes and Generalized Mixed Yule-coalescent - were used to help delimit ant species based on COI sequences, and their results corresponded well with most of the morphospecies. All three approaches indicate cryptic diversity may exist within Tetramorium bicarinatum and Technomyrmex albipes, with intraspecific genetic distances of 7.7% and 6.24%, respectively. Our analyses also reported five species for the first time from Fujian Province of China, and the COI sequences of nine species are newly added into the GenBank. This study provides information about species diversity of aphid-associated ants in subtropical China and compiles a DNA barcode reference library for future ant barcoding work.