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

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.

The Nutritional Profiles of Five Important Edible Insect Species From West Africa—An Analytical and Literature Synthesis

“…Stark genetic differences have indeed been found between edible insect populations globally. For example, high mitochondrial and microsatellite diversity and structure has been identified in H. illucens ( 115 , 116 ) and M. domestica ( 117 , 118 ). This genetic divergence could potentially translate into nutritional differences.…”

Valorisation Potential of Using Organic Side Streams as Feed for Tenebrio molitor, Acheta domesticus and Locusta migratoria

“…Recent work on the black soldier fly, using 15 microsatellite genetic markers, captured the genetic diversity of global and domesticated BSF populations and suggests the importance of the genetic make-up of BSF populations [130]. The recent sequencing of the BSF genome and the genetic manipulation of BSF towards an enhanced feeding capacity phenotype [126] further illustrate future opportunities for more efficient insect farming.…”

Patterns of Genetic Diversity and Mating Systems in a Mass-Reared Black Soldier Fly Colony

“…In particular, the production of Hermetia illucens (L. 1758; Diptera: Stratiomyidae) (black soldier fly, BSF) has increased considerably in recent years [ 3 , 4 ]. The popularity of the species is due to the larvae’s comparative nutrient profile to conventional protein sources like soy and fishmeal [ 5 , 6 , 7 ] and its global, cosmopolitan distribution [ 8 ]. The species is thought to have originated in South America and has since spread to most (sub)tropical and temperate regions of the world, highlighting the BSF’s adaptability to a variety of conditions [ 8 ].…”

“…The popularity of the species is due to the larvae’s comparative nutrient profile to conventional protein sources like soy and fishmeal [ 5 , 6 , 7 ] and its global, cosmopolitan distribution [ 8 ]. The species is thought to have originated in South America and has since spread to most (sub)tropical and temperate regions of the world, highlighting the BSF’s adaptability to a variety of conditions [ 8 ]. Furthermore, the larvae are efficient feeders of organic waste, creating the opportunity for circular and renewable agricultural systems, where larvae feed on agricultural waste and in turn larval products are used in animal feed and plant fertiliser production [ 9 , 10 ].…”