Search

Additional file 2: Table S2. Microsatellite marker characteristics of the novel Hermetia illucens population genetics tool kit. Table S3. Population genetic characteristics of 150 wild and captive Hermetia illucens populations. Table S4. Countries of origin of investigated Hermetia illucens populations. Table S5. Population genetic characteristics according to subcontinental origin and provenance status (wild vs. captive). Table S6. Diversity and pairwise differentiation of globally inferred genetic clusters of Hermetia illucens. Table S7. AMOVA nesting provenance (wild vs. captive) within subcontinents for worldwide Hermetia illucens populations. Table S8. Model-based estimates of contrasts and significance levels for population-specific allelic richness. Table S9. Genetic isolation by distance for selected hierarchical groupings. Table S10. Specifications on the global distribution of Hermetia illucens genetic clusters presented in Fig. 4. Table S11. Details on ABC analyses. Table S12. Posterior probabilities of demographic models inferred from ABC analyses. Table S13. Estimates of posterior distributions of population genetic parameters inferred from ABC analyses. Table S14. Selected group comparisons of inbreeding coefficients FIS. Table S15. Group-specific comparisons of variance component ratios for linkage disequilibrium between (DST) and within (DIS) populations. Table S16. Microsatellite properties relevant for ABC analyses. Figure S1. Discriminatory power of the novel microsatellite marker set for Hermetia illucens genotyping. Figure S2. Significant deviations from Hardy-Weinberg equilibrium for individual microsatellite loci tested within populations. Figure S3. Computational details on genetic cluster analyses and retaining discriminatory functions for visualisation. Figure S4. Global population genetic patterns of Hermetia illucens according to provenance (wild vs. captive) nested within subcontinent of origin. Figure S5. Neighbour-joining tree based on population pairwise FST across 150 Hermetia illucens populations. Figure S6. Demographic inference with ABC. Figure S7. Detection of hybrids and backcrosses: a west African case of introgression. Figure S8. Detection of hybrids and backcrosses: case-specific analyses of central-east African populations and predominantly farmed populations from Asia.

Background: The black soldier fly (Hermetia illucens) is the most promising insect candidate for nutrient-recycling through bioconversion of organic waste into biomass, thereby improving sustainability of protein supplies for animal feed and facilitating transition to a circular economy. Contrary to conventional livestock, genetic resources of farmed insects remain poorly characterised. We present the first comprehensive population genetic characterisation of H. illucens. Based on 15 novel microsatellite markers, we genotyped and analysed 2862 individuals from 150 wild and captive populations originating from 57 countries on seven subcontinents. Results: We identified 16 well-distinguished genetic clusters indicating substantial global population structure. The data revealed genetic hotspots in central South America and successive northwards range expansions within the indigenous ranges of the Americas. Colonisations and naturalisations of largely unique genetic profiles occurred on all non-native continents, either preceded by demographically independent founder events from various single sources or involving admixture scenarios. A decisive primarily admixed Polynesian bridgehead population serially colonised the entire Australasian region and its secondarily admixed descendants successively mediated invasions into Africa and Europe. Conversely, captive populations from several continents traced back to a single North American origin and exhibit considerably reduced genetic diversity, although some farmed strains carry distinct genetic signatures. We highlight genetic footprints characteristic of progressing domestication due to increasing socio-economic importance of H. illucens, and ongoing introgression between domesticated strains globally traded for large-scale farming and wild populations in some regions. Conclusions: We document the dynamic population genetic history of a cosmopolitan dipteran of South American origin shaped by striking geographic patterns. These reflect both ancient dispersal routes, and stochastic and heterogeneous anthropogenic introductions during the last century leading to pronounced diversification of worldwide structure of H. illucens. Upon the recent advent of its agronomic commercialisation, however, current human-mediated translocations of the black soldier fly largely involve genetically highly uniform domesticated strains, which meanwhile threaten the genetic integrity of differentiated unique local resources through introgression. Our in-depth reconstruction of the contemporary and historical demographic trajectories of H. illucens emphasises benchmarking potential for applied future research on this emerging model of the prospering insect-livestock sector.

BACKGROUND: The black soldier fly (Hermetia illucens) is the most promising insect candidate for nutrient-recycling through bioconversion of organic waste into biomass, thereby improving sustainability of protein supplies for animal feed and facilitating transition to a circular economy. Contrary to conventional livestock, genetic resources of farmed insects remain poorly characterised. We present the first comprehensive population genetic characterisation of H. illucens. Based on 15 novel microsatellite markers, we genotyped and analysed 2862 individuals from 150 wild and captive populations originating from 57 countries on seven subcontinents. RESULTS: We identified 16 well-distinguished genetic clusters indicating substantial global population structure. The data revealed genetic hotspots in central South America and successive northwards range expansions within the indigenous ranges of the Americas. Colonisations and naturalisations of largely unique genetic profiles occurred on all non-native continents, either preceded by demographically independent founder events from various single sources or involving admixture scenarios. A decisive primarily admixed Polynesian bridgehead population serially colonised the entire Australasian region and its secondarily admixed descendants successively mediated invasions into Africa and Europe. Conversely, captive populations from several continents traced back to a single North American origin and exhibit considerably reduced genetic diversity, although some farmed strains carry distinct genetic signatures. We highlight genetic footprints characteristic of progressing domestication due to increasing socio-economic importance of H. illucens, and ongoing introgression between domesticated strains globally traded for large-scale farming and wild populations in some regions. CONCLUSIONS: We document the dynamic population genetic history of a cosmopolitan dipteran of South American origin shaped by striking geographic patterns. These reflect both ancient dispersal routes, and stochastic and heterogeneous anthropogenic introductions during the last century leading to pronounced diversification of worldwide structure of H. illucens. Upon the recent advent of its agronomic commercialisation, however, current human-mediated translocations of the black soldier fly largely involve genetically highly uniform domesticated strains, which meanwhile threaten the genetic integrity of differentiated unique local resources through introgression. Our in-depth reconstruction of the contemporary and historical demographic trajectories of H. illucens emphasises benchmarking potential for applied future research on this emerging model of the prospering insect-livestock sector.