Mitochondrial genomes and polymorphic regions of Gonimbrasia belina and Gynanisa maja (Lepidoptera: Saturniidae), two important edible caterpillars of Southern Africa

Evaluating the mitochondrial genomic diversity, global distribution and niche overlap of two invasive Phthorimaea species

This study sought to evaluate the genetic diversity of two invasive Phthorimaea species (Phthorimaea operculella Zeller and Phthorimaea absoluta Meyrick), and identify potential niche overlap of both species. The complete mitogenomes of P. operculella and P. absoluta were sequenced and compared. Furthermore, the diversity within the family Gelechiidae was assessed. Subsequently, two species distribution models (MaxEnt and BIOCLIM) were used to identify niche overlaps of both species globally. The complete mitogenomes of both species were similar in size and structure, with a pairwise identity of 92.3%. The models showed a niche overlap of both species and revealed areas of marginal to high suitability for both pests in countries where they have not been reported. Therefore, these results present a compelling case for a deeper genetic and ecological investigation of the Gelechiidae family for taxonomic harmonization, an early warning for surveillance, stricter phytosanitary considerations and preventive management against the spread of the pests.

Characterization of Seventeen Complete Mitochondrial Genomes: Structural Features and Phylogenetic Implications of the Lepidopteran Insects

Lepidoptera (moths and butterflies) are widely distributed in the world, but high-level phylogeny in Lepidoptera remains uncertain. More mitochondrial genome (mitogenome) data can help to conduct comprehensive analysis and construct a robust phylogenetic tree. Here, we sequenced and annotated 17 complete moth mitogenomes and made comparative analysis with other moths. The gene order of trnM-trnI-trnQ in 17 moths was different from trnI-trnQ-trnM of ancestral insects. The number, type, and order of genes were consistent with reported moths. The length of newly sequenced complete mitogenomes ranged from 14,231 bp of Rhagastis albomarginatus to 15,756 bp of Numenes albofascia. These moth mitogenomes were typically with high A+T contents varied from 76.0% to 81.7% and exhibited negative GC skews. Among 13 protein coding genes (PCGs), some unusual initiations and terminations were found in part of newly sequenced moth mitogenomes. Three conserved gene-overlapping regions and one conserved intergenic region were detected among 17 mitogenomes. The phylogenetic relationship of major superfamilies in Macroheterocera was as follows: (Bombycoidea + Lasiocampoidea) + ((Drepanoidea + Geometroidea) + Noctuoidea)), which was different from previous studies. Moreover, the topology of Noctuoidea as (Notodontidae + (Erebidae + Noctuidae)) was supported by high Bayesian posterior probabilities (BPP = 1.0) and bootstrapping values (BSV = 100). This study greatly enriched the mitogenome database of moth and strengthened the high-level phylogenetic relationships of Lepidoptera.

Genetic diversity of Diaphorina citri (Hemiptera: Liviidae) unravels phylogeographic structure and invasion history of eastern African populations

The Asian citrus psyllid (Diaphorina citri Kuwayama) is a key pest of Citrus sp. worldwide, as it acts as a vector for Candidatus Liberibacter asiaticus, the bacterial pathogen that causes citrus Huanglongbing. Diaphorina citri has been reported in Kenya, Tanzania, and more recently in Ethiopia. This study assessed the genetic diversity and phylogeographic structure of the pest to gain insights into the potential sources of its introduction into Africa. Population structure and differentiation of D. citri populations from China, Ethiopia, Kenya, Tanzania, and the USA were assessed using 10 microsatellite loci. Additionally, five new complete mitogenomes of D. citri collected in China, Ethiopia, Kenya, Tanzania, and the USA were analyzed in the context of publicly available sequences. Genotype data grouped the D. citri populations from Kenya and Tanzania in one cluster, and those from Ethiopia formed a separate cluster. The two genetic clusters inferred from genotype data were congruent with mitochondrial sequence data. The mitogenomes from Kenya/Tanzania/China had 99.0% similarity, and the Ethiopia/USA had 99.9% similarity. In conclusion, D. citri populations in eastern Africa have different sources, as the Kenyan and Tanzanian populations probably originated from southeastern Asia, while the Ethiopian population most probably originated from the Americas.

Mitogenomics and phylogenetics of twelve species of African Saturniidae (Lepidoptera)

African Saturniidae (Lepidoptera) include numerous species consumed at the caterpillar stage throughout the continent, and their importance to local communities as a source of nutrition and seasonal income cannot be overestimated. However, baseline genetic data with utility for the characterization of their diversity, phylogeography and phylogenetic relationships have remained scarce compared to their Asian counterparts. To bridge this gap, we sequenced the mitochondrial genomes of 12 species found in southern Africa for comparative mitogenomics and phylogenetic reconstruction of the family, including the first representatives of the tribes Eochroini and Micragonini. Mitochondrial gene content and organization were conserved across all Saturniidae included in the analyses. The phylogenetic positions of the 12 species were assessed in the context of publicly available mitogenomes using Bayesian inference and maximum likelihood (ML) methods. The monophyly of the tribes Saturniini, Attacini, Bunaeini and Micragonini, the sister relationship between Saturniini and Attacini, and the placement of Eochroa trimenii and Rhodinia fugax in the tribes Eochroini and Attacini, respectively, were strongly supported. These results contribute to significantly expanding genetic data available for African Saturniidae and allow for the development of new mitochondrial markers in future studies.

First complete mitochondrial genome of Rhodinia species (Lepidoptera: Saturniidae): genome description and phylogenetic implication

To explore the characteristics of the mitochondrial genome (mitogenome) of the squeaking silkmoths Rhodinia, a genus of wild silkmoths in the family Saturniidae of Lepidoptera, and reveal phylogenetic relationships, the mitogenome of Rhodinia fugax Butler was determined. This wild silkmoth spins a green cocoon that has potential significance in sericulture, and exhibits a unique feature that its larvae can squeak loudly when touched. The mitogenome of R. fugax is a circular molecule of 15,334 bp long and comprises 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and an A + T-rich region, consistent with previous observations of Saturniidae species. The 370-bp A + T-rich region of R. fugax contains no tandem repeat elements and harbors several features common to the Bombycidea insects, but microsatellite AT repeat sequence preceded by the ATTTA motif is not present. Mitogenome-based phylogenetic analysis shows that R. fugax belongs to Attacini, instead of Saturniini. This study presents the first mitogenome for Rhodinia genus.

Overview of the Genetic Diversity of African Macrotermes (Termitidae: Macrotermitinae) and Implications for Taxonomy, Ecology and Food Science

Simple Summary

Macrotermes are fungus-growing termites known as ecosystem engineers for their role in cellulose recycling and soil conditioning. Macrotermes termites are also important as edible insects and are widely consumed throughout Africa. Accurate identification of Macrotermes species is challenging because of few and unreliable morphological differences among taxonomic groups. Due to this limitation, the diversity of African Macrotermes is incompletely described. Genetic data has provided new insights, but vast geographic regions remain unsurveyed. We generated COI data for specimens collected in Limpopo, South Africa, where Macrotermes termites are commonly consumed by local populations, and assessed their diversity in the context of publicly available sequences. We identified 17 genetic groups that most likely represented distinct species, in contrast with the 13 Macrotermes species currently described in Africa. The specimens collected in Limpopo belonged to four genetic groups, suggesting a high diversity of Macrotermes in the region. Our results also showed that Macrotermes species names and genetic groups do not match in most cases, likely due to inaccurate identification of specimens. We propose that the genetic groups that are identified here be used as a background to guide future studies of African Macrotermes with a positive impact on food science, ecology, taxonomy, phylogeography and phylogenetics.

Abstract

Macrotermes termites play important ecological roles and are consumed by many communities as a delicacy and dietary complement throughout Africa. However, lack of reliable morphological characters has hampered studies of Macrotermes diversity in a wide range of scientific fields including ecology, phylogenetics and food science. In order to place our preliminary assessment of the diversity of Macrotermes in South Africa in context, we analysed a comprehensive dataset of COI sequences for African species including new and publicly available data. Phylogenetic reconstruction and estimates of genetic divergence showed a high level of incongruity between species names and genetic groups, as well as several instances of cryptic diversity. We identified three main clades and 17 genetic groups in the dataset. We propose that this structure be used as a background for future surveys of Macrotermes diversity in Africa, thus mitigating the negative impact of the present taxonomic uncertainties in the genus. The new specimens collected in Limpopo fell into four distinct genetic groups, suggesting that the region harbours remarkable Macrotermes diversity relative to other African regions surveyed in previous studies. This work shows that African Macrotermes have been understudied across the continent, and that the genus contains cryptic diversity undetectable by classic taxonomy. Furthermore, these results may inform future taxonomic revisions in Macrotermes, thus contributing to advances in termitology.

Complete mitochondrial genome of Actias dubernardi (Lepidoptera: Saturniidae)

The complete mitochondrial genome of Actias dubernardi (Lepidoptera: Saturniidae) is 15,270 bp in length, containing 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and a putative control region. All of the protein-coding genes (PCGs) use the standard start codon ATN, except for cox1 which starts with CGA. The Bayesian phylogenetic analysis was performed using a dataset matrix containing 13 PCGs concatenated from the mitogenomes of 14 Saturniidae species. The monophyly of the five Actias species was highly supported and Antheraea was inferred as the sister group of Actias.