Browsing by Author "Straeuli, Rieze"

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    Phylogeny of emperor moths and phylogeography of gonimbrasia belina in Southern Africa
    (Stellenbosch : Stellenbosch University, 2022-12) Straeuli, Rieze; Van Asch, Barbara; Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics.
    ENGLISH ABSTRACT: Lepidoptera is one of the most diverse insect orders found worldwide. African Emperor moths (Saturniidae) are understudied despite their ecological and economic relevance, as the caterpillars of many species are utilized for human consumption. Gonimbrasia belina occurs in woodlands of Colophospermum mopane (mopane tree) and Brachystegia sp. (miombo tree) across southern Africa. Mopane worms, the vernacular name for the edible caterpillars of G. belina, is regarded as the most important edible Saturniidae caterpillar in Africa as it provides not only food but also seasonal income for rural communities. As a result, mopane worms are widely harvested in southern Africa due to their high nutrient content and income generating potential. Increased demands for favoured edible Saturniidae species, habitat destruction and unregulated harvesting are placing wild populations in serious danger of decline. Currently, most research on the genetic diversity of Saturniidae has focused on species farmed in Asia for silk production. African Saturniidae have remained largely unsurveyed, and mitochondrial phylogenies of the family have so far included only G. belina and Gynanisa maja, two of the most exploited edible caterpillars in southern Africa. This study aimed to bridge this knowledge gap by generating baseline genetic data on seven African Saturniidae species in three tribes: Heniocha dyops, Gonimbrasia tyrrhea, Bunaea alcinoe, Nudaurelia cytherea (Bunaeini), Epiphora bauhinia (Attacini), Vegetia ducalis (Micragonini) and Vegetia grimmia (Micragonini). For that purpose, I sequenced and described the complete mitogenome of one individual of each species and inferred their phylogenetic relationships with other Saturniidae. The mitochondrial gene content and organisation was conserved across all Saturniidae species in this study. Bayesian Inference and Maximum likelihood phylogenetic reconstructions were performed separately for three datasets: (1) PCG123 - all PCGs and all codon positions, (2) PCG12 - all PCGs with 3ʳᵈ codon position removed; and (3) PCG123+rRNA – all PCGs and two rRNAs (16s rRNA and 12s rRNA). Previous studies showed similar results, in that none of the phylogenies recovered a monophyletic tribal structure in Saturniini. However, the tribes Attacini, Bunaeini and Micragonini were recovered as monophyletic clades. Additionally, the tribe Micragonini (represented by Vegetia ducalis and Vegetia grimmia) is here included for the first time in the comparative mitogenomics and mitochondrial phylogeny of the family Saturniidae. In the context of edible caterpillars of African Saturniidae, special attention was dedicated to G. belina because of its large-scale exploitation in southern Africa. I aimed to assess the intra-specific genetic diversity, population structure and phylogeographic structure of the species in South Africa, Namibia and Botswana by analysing two short polymorphic mitochondrial amplicons (Amplicon A; 600 bp; located between ATP6 and COIII, and Amplicon C; 888 bp; located between ND6 and CYTB) in addition to the standard COI barcoding region (700 bp). Overall, G. belina had 22 haplotypes and all three counties exhibited low levels of nucleotide diversity and high levels of haplotype diversity, with only one haplotype shared between South Africa and Botswana. Genetic divergence in G. belina corresponds to the broad geographical area of origin of the specimens. A maximum likelihood tree showed that most haplotypes clustered into three groups corresponding to the three countries, evidencing significant phylogeographic structure in G. belina. The findings from this study provide valuable information for future studies on the population structure of G. belina, and offers baseline data from which biodiversity hotspots may be identified in the future to inform sustainable harvesting and conservations plans in order to preserve this species.