Impact of Microbiota on Development: Rearing Axenic Black Soldier Fly ( Hermetia illucens ) Larvae

Abstract

The microbiota’s impact on host’s development, metabolism and immunology has made microbial study integral to the biology of organisms. Microorganisms coevolve with their host and can be vital for development, to the point that some host cannot survive in their absence. Studies have explored Hermetia illucens (BSF) microbiome, an insect prized for its ability to process organic waste and its quality as livestock feed, but microbial aspects of the insect health and performance are still neglected. We hypothesise that BSF’s microbiota affect host’s ontology. To better understand host-microbiota’s interacting factors on BSF, we developed a rearing method in sterile conditions (axenic larvae) by treating egg clutches with ethanol and active chlorine washes. Although the growth of axenic larvae is affected, they can survive and feed. In the future, the impact of host-microbiota interactions factored with diet and life stages will be explored by the study of differential gene expression.

Full text

Impact of Microbiota on Development: Rearing Axenic Black Soldier Fly (Hermetia illucens) Larvae
Laurence Auger1,2, Marie-Hélène Deschamps3, Grant Vandenberg3et Nicolas Derome1,2
1Biology Department, Laval University, Quebec, (Canada), 2Institut de Biologie Intégrative des
Systèmes (IBIS), Quebec, (Canada), 3Department of Animal Science, Quebec, (Canada)
Introduction Results
Hermetia illucens (BSF):
•The larva develop by eating animal & vegetal waste
•The larva is used as animal feed
•The larva has antimicrobial capacities
•Microbiological aspects of BSF health status,
ontology and physiological performance have been
neglected
Objectives
We aim to develop a BSF larvae rearing experimental model in which we can control factors that
modulate host-microbiota functional interactions and more specifically to:
1) Determine if larvae can be reared in axenic conditions
2) Determine if axenic conditions affect BSF larvae development (body length)
Material and Methods
Day 0
Sampling:
Day 4, 8, 12,
16 and 20
Conclusion and perspectives
Bibliography
De Smet, J., Wynants, E., Cos, P., Van Campenhout, L. (2018) Microbial Community Dynamics during Rearing of Black Soldier Fly
Larvae (Hermetia illucens) and Impact on Exploitation Potential. Appl Environ Micobiol, 84(9), 1-17.
Acknowledgments
Substrate: BHI supplemented with YPD agar medium
•BSF larva can grow in axenic conditions
• Larval length wasn’t significantly affected by axenic conditions
•Substrate affect development ( day 50: no sign of pupation, usually on day 25)
Upcoming studies
•Investigate BSF larval growth on different media in axenic conditions
•Manipulate microbiota to optimize biomass production and antimicrobial properties
Microbiota influences the host
Axenic BSF larva:
Larva without any other organisms (no microbiota)
Metabolic activity
Reproduction
Immune response
Communication
Physiology
Resistances
3 min/solution
9 min
2.5%
active
chlorine 70% EtOH Sterile
water
Sterile
water
Axenic
Control 6 X 150
6 X 150
Contact
Laurence Auger
PhD Student
laurence.auger.1@ulaval.ca
Day 1
How to verify the axenic conditions
16S rRNA: ribosome subunit specific to prokaryotes
V1 V2 V3 V4 V5 V6 V7 V8 V9
•Variable regions
•Conserved regions
PCR amplification
16S rRNA gene Agarose gel migration:
Band = prokaryote present
No band = prokaryote absent
Fig 2. Agarose gel
of 16S PCR shows
bands for(A)
control samples on
day 4, (B) control
samples on day 20
and absence of
bands for (C)
axenic samples on
day 4, (D) axenic
samples on day 20
and (E) negative
control
ABC D E
Ladder
How to produce axenic larvae
Fig 1. BHI supplemented agar
medium eaten by larvae
Network of microbial interactionDifferential gene expression
Eggs
0
2
4
6
8
10
12
14
16
18
20
04812 16 20 24
Length (mm)
Age (days)
control
axenic
gainesville
Fig 3. Total larval length variation on a period of 20 days (day 1 =
hatching) when grown in axenic or control conditions on agar medium
and on gainesville substrate at 27˚C and RH 70% (N=10)