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Global population genetic structure and demographic trajectories of the black soldier fly, Hermetia illucens.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Kaya, Cengiz 
Generalovic, Tomas N 
Ståhls, Gunilla 
Hauser, Martin 
Samayoa, Ana C 

Abstract

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.

Description

Keywords

Diptera, Genetic differentiation, Genetic drift, Invasive species, Allelic richness, founder effect, Isolation By Distance, Stratiomyidae, Approximate Bayesian Computation, Serial Introductions

Journal Title

BMC biology

Conference Name

Journal ISSN

1741-7007

Volume Title

19

Publisher

Sponsorship
Bundesamt für Landwirtschaft (627000824)
Australian Centre for International Agricultural Research (108866-001)
Swiss National Science Foundation (400540_152154, IZ01Z0_147278)
Austrian Science Fund FWF (FWF P32275)
National Research Foundation, South Africa (CSRP170506229933)