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The puzzling mitochondrial phylogeography of the black soldier fly (Hermetia illucens), the commercially most important insect protein species
Gunilla Ståhls
Luonnontieteellinen keskusmuseo
Corresponding Author
ORCiD: https://orcid.org/0000-0003-0505-0691
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This work is licensed under a CC BY 4.0 License. Read Full License
Background The black soldier fly (Diptera: Stratiomyidae, Hermetia illucens) is renowned for its bioconversion ability of organic matter, and is the worldwide most widely used source of insect protein. Despite varying extensively in morphology, it is widely assumed that all black soldier flies belong to the same species, Hermetia illucens. We here screened about 600 field-collected and cultured flies from 39 countries and six biogeographic regions to test this assumption based on data for three genes (mitochondrial COI, nuclear ITS2 & 28S rDNA) and in order to gain insights into the phylogeography of the species.
Results Our study reveals a surprisingly high level of intraspecific genetic diversity for the mitochondrial barcoding gene COI (divergences up to 4.9%). This level of variability is often associated with the presence of multiple species, but tested nuclear markers (ITS2 and 28S rDNA) were invariant and fly strain hybridization experiments under laboratory conditions revealed reproductive compatibility. COI haplotype diversity is not only very high in all biogeographic regions (56 distinct haplotypes in total), but also in breeding facilities and research centers from six continents (10 haplotypes: divergences up to 4.3%). The high genetic diversity in fly-breeding facilities is mostly likely due to many independent acquisitions of cultures via sharing and/or establishing new colonies from field-collected flies. However, explaining some of the observed diversity in several biogeographic regions is difficult given that the origin of the species is considered to be New World (32 distinct haplotypes) and one would expect severely reduced genetic diversity in the putatively non-native populations in the remaining biogeographic regions. However, distinct, private haplotypes are known from the Australasian (N=1), Oriental (N=4), and the Eastern Palearctic (N=4) populations. We reviewed museum specimen records and conclude that the evidence for introductions is strong for the Western Palearctic and Afrotropical regions which lack distinct, private haplotypes.
Conclusions Based on the results of this paper, we urge the black soldier fly community to apply molecular characterization (genotyping) of the fly strains used in artificial fly-breeding and share these data in research publications as well as when sharing cultures. In addition, fast-evolving nuclear markers should be used to reconstruct the recent invasion history of the species.
Keywords
Black soldier fly, Hermetia illucens, mtDNA COI haplotypes, nuclear rDNA
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Received 23 Apr, 2020
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On 01 Apr, 2020
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On 01 Apr, 2020
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On 31 Mar, 2020
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On 30 Mar, 2020
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Editorial decision: Major revision
On 14 Feb, 2020
Review #3 received
Received 12 Feb, 2020
Review #2 received
Received 09 Feb, 2020
Review #1 received
Received 20 Jan, 2020
Reviewer #3 agreed
On 11 Jan, 2020
Reviewer #2 agreed
On 10 Jan, 2020
Reviewer #1 agreed
On 09 Jan, 2020
Reviewers invited
Invitations sent on 08 Jan, 2020
Editor assigned
On 23 Dec, 2019
Submission checks complete
On 22 Dec, 2019
Editor invited
On 22 Dec, 2019
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On 19 Dec, 2019
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This preprint is under consideration at BMC Ecology and Evolution. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research article
The puzzling mitochondrial phylogeography of the black soldier fly (Hermetia illucens), the commercially most important insect protein species
Gunilla Ståhls
Luonnontieteellinen keskusmuseo
Corresponding Author
ORCiD: https://orcid.org/0000-0003-0505-0691
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 3
Posted 21 May, 2020
No community comments so far
Submission checks complete
On 14 May, 2020
No comments provided
Editorial decision: Minor revision
On 07 May, 2020
Review #2 received
Received 27 Apr, 2020
Review #1 received
Received 23 Apr, 2020
Reviewers invited
Invitations sent on 01 Apr, 2020
Reviewer #1 agreed
On 01 Apr, 2020
Reviewer #2 agreed
On 01 Apr, 2020
Editor assigned
On 31 Mar, 2020
Submission checks complete
On 30 Mar, 2020
Editor invited
On 30 Mar, 2020
No comments provided
Editorial decision: Major revision
On 14 Feb, 2020
Review #3 received
Received 12 Feb, 2020
Review #2 received
Received 09 Feb, 2020
Review #1 received
Received 20 Jan, 2020
Reviewer #3 agreed
On 11 Jan, 2020
Reviewer #2 agreed
On 10 Jan, 2020
Reviewer #1 agreed
On 09 Jan, 2020
Reviewers invited
Invitations sent on 08 Jan, 2020
Editor assigned
On 23 Dec, 2019
Submission checks complete
On 22 Dec, 2019
Editor invited
On 22 Dec, 2019
First submitted
On 19 Dec, 2019
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background The black soldier fly (Diptera: Stratiomyidae, Hermetia illucens) is renowned for its bioconversion ability of organic matter, and is the worldwide most widely used source of insect protein. Despite varying extensively in morphology, it is widely assumed that all black soldier flies belong to the same species, Hermetia illucens. We here screened about 600 field-collected and cultured flies from 39 countries and six biogeographic regions to test this assumption based on data for three genes (mitochondrial COI, nuclear ITS2 & 28S rDNA) and in order to gain insights into the phylogeography of the species.
Results Our study reveals a surprisingly high level of intraspecific genetic diversity for the mitochondrial barcoding gene COI (divergences up to 4.9%). This level of variability is often associated with the presence of multiple species, but tested nuclear markers (ITS2 and 28S rDNA) were invariant and fly strain hybridization experiments under laboratory conditions revealed reproductive compatibility. COI haplotype diversity is not only very high in all biogeographic regions (56 distinct haplotypes in total), but also in breeding facilities and research centers from six continents (10 haplotypes: divergences up to 4.3%). The high genetic diversity in fly-breeding facilities is mostly likely due to many independent acquisitions of cultures via sharing and/or establishing new colonies from field-collected flies. However, explaining some of the observed diversity in several biogeographic regions is difficult given that the origin of the species is considered to be New World (32 distinct haplotypes) and one would expect severely reduced genetic diversity in the putatively non-native populations in the remaining biogeographic regions. However, distinct, private haplotypes are known from the Australasian (N=1), Oriental (N=4), and the Eastern Palearctic (N=4) populations. We reviewed museum specimen records and conclude that the evidence for introductions is strong for the Western Palearctic and Afrotropical regions which lack distinct, private haplotypes.
Conclusions Based on the results of this paper, we urge the black soldier fly community to apply molecular characterization (genotyping) of the fly strains used in artificial fly-breeding and share these data in research publications as well as when sharing cultures. In addition, fast-evolving nuclear markers should be used to reconstruct the recent invasion history of the species.
Figure 1
Figure 2