Genetic and phenotypic consequences of early domestication in black soldier flies (Hermetia illucens)

Abstract

Summary The black soldier fly, Hermetia illucens, is an emerging biotechnological agent with its larvae being effective converters of organic waste into usable bio‐products including protein and lipids. To date, most operations use unimproved commercial populations produced by mass rearing, without cognisance of specific breeding strategies. The genetic and phenotypic consequences of these commercial practices remain unknown and could have a significant impact on long‐term population viability and productivity. The aim of this study was thus to assess the genetic and phenotypic changes during the early phases of colony establishment and domestication in the black soldier fly. An experimental colony was established from wild founder flies and a new microsatellite marker panel was developed to assess population genetic parameters along with the phenotypic characteristics of each generational cohort under captive breeding. The experimental colony was characterised by a small effective population size, subsequent loss of genetic diversity and rapid genetic and phenotypic differentiation between the generational cohorts. Ultimately, the population collapsed by the fifth generation, most likely owing to the adverse effect of inbreeding depression following the fixation of deleterious alleles. Species with r‐selected life history characteristics (e.g. short life‐span, high fecundity and low larval survival) are known to pose particular challenges for genetic management. The current study suggests that sufficient genetic and phenotypic variations exist in the wild population and that domestication and strain development could be achieved with careful population augmentation and selection during the early stages of colony establishment.

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

“…Wild 2015 had a significantly negative mean pairwise relatedness, and the cohort exhibited low observed heterozygosity compared to the expected heterozygosity ( Figure 1 ), consistent with the Wahlund effect [ 74 ]. These findings suggest that Wild 2015 was sampled from a recently admixed population of two genetically differentiated populations, which was further supported by the observation of isolate breaking when this cohort was allowed to interbreed in a study by Rhode et al [ 11 ]. The apparent sampling of genetically distinct populations in Wild 2015 may be a result of cryptic genetic structure in the wild BSF population.…”

“…Eight microsatellite loci previously developed by Rhode et al [ 11 ] were amplified in three multiplex PCR reactions. A final reaction volume of 10 µL included KAPA2G™ Fast Multiplex PCR Mix, 20 ng of genomic DNA and 0.8 µM of each fluorescently labelled forward primer and reverse primer.…”

“…Knowledge on the impact of induced domestication on the genetic health of commercial colonies is therefore limited. Rhode et al [ 11 ] have shown that the early stages of captive rearing of a wild-caught BSF colony can have major effects on genetic composition and phenotypic development, and place such a colony at risk of collapse. The adverse effects of captive mass-rearing and domestication are associated with the loss of genetic diversity.…”

Selection for age at reproduction changes pre‐mating period and mating frequency in Zeugodacus cucurbitae: impacts on insect quality control

“…The method to collect eggs from young females to improve reproductive efficiency when propagating insects is not limited to Z. cucurbitae. It is likely a common practice in the mass-rearing of other organisms used in SIT programs or biological control agents for other species (Calkins & Parker, 2005;Gilchrist et al, 2012;Hoffmann & Ross, 2018;Rhode et al, 2020). In the future, it is necessary to consider the costs and benefits of producing mass-reared strains for SIT programs with regard to sustainability in terms of mating behavior and reproductive schedules.…”

A high-quality, chromosome-level genome assembly of the Black Soldier Fly (Hermetia IllucensL.)

“…The genome wide inbreeding coefficient estimated from these ROH was 0.019 (excluding the identified sex chromosome, see below). This established captive EVE line does not appear to be hindered by inbreeding depressions unlike previous inbred populations which have experienced severe colony crash events [68]. However, small sample size (n=12) may provide a bias distribution of allele frequencies for inbreeding calculations.…”