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

Anandi Bierman,Rozane Badenhorst,Lelanie Hoffmann,Aletta E. Bester-van der Merwe,Clint Rhode,Kelvin L. Hull

doi:10.3390/insects12060480

Abstract

The black soldier fly (BSF), Hermetia illucens, is a promising candidate for the emerging insect farming industry with favourable characteristics for both bioremediation and production of animal delivered nutritive and industrial compounds. The genetic management of commercial colonies will become increasingly important for the sustainability of the industry. However, r-selected life history traits of insects pose challenges to conventional animal husbandry and breeding approaches. In this study, the long-term genetic effects of mass-rearing were evaluated as well as mating systems in the species to establish factors that might influence genetic diversity, and by implication fitness and productivity in commercial colonies. Population genetic parameters, based on microsatellite markers, were estimated and compared amongst two temporal wild sampling populations and four generations (F28, F48, F52, and F62) of a mass-reared colony. Furthermore, genetic relationships amongst mate pairs were evaluated and parentage analysis was performed to determine the oc-currence of preferential mate choice and multiple paternity. The mass-reared colony showed a reduction in genetic diversity and evidence for inbreeding with significant successive generational genetic differentiation from the wild progenitor population. Population-level analysis also gave the first tentative evidence of positive assortative mating and genetic polyandry in BSF. The homoge-neity of the mass-reared colony seems to result from a dual action caused by small effective popu-lation size and increased homozygosity due to positive assortative mating. However, the high ge-netic diversity in the wild and a polyandrous mating system might suggest the possible restoration of diversity in mass-reared colonies through augmentation with the wild population.

Highlights

As the global human population continues to grow, the sustainability of agricultural production and food security is becoming an increasing concern, especially considering global climate change and diminishing natural resources
The black soldier fly has shown particular promise as both a bioremedial agent and a source of usable animal protein and other bio-products, which has led to the establishment of large industrial production facilities
Particular emphasis is being placed on genetic management and selective breeding for the enhancement of production characteristics in commercial populations

Summary

Introduction

As the global human population continues to grow, the sustainability of agricultural production and food security is becoming an increasing concern, especially considering global climate change and diminishing natural resources. To meet the growing demand for alternative sources of protein, the mass-rearing of insects has gained attention worldwide. This is due to the low input costs, resource ‘lite’ nature, and high feed conversion ratios of insects [1,2]. 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 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]

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