Audrie French

Document Type

Honors Thesis

Major

Microbiology

Advisor(s)

Edward Bernard

Committee Members

Margaret Killinger, Robert Wheeler

Graduation Year

May 2023

Publication Date

2025

Abstract

Black soldier fly (Hermetia illucens) larvae (BSFL) are being increasingly used as a sustainable high-protein feed alternative for aquaculture, poultry, and swine. They are authorized as feed in the US for salmonids and poultry. Much of the current research on BSFL is focused on the efficacy and viability of the insect as a feed source but the larvae also have an important effect on bacteria within their feed (substrate). Certain bacteria (like Staphylococcus aureus) are present in significantly lower concentrations in substrates upon which larvae are feeding. Other bacterial species, such as Aeromonas hydrophila and Vibrio parahaemolyticus do not have the same suppressive affect. Investigating the immune response of the larvae to these pathogens provides insight into possible mechanisms of pathogen suppression. A possible TRAF2 homolog in the BSFL, involved in the NF-kB signaling pathway in insects shows differences in expression when exposed to these Gram-negative pathogens. This indicates that something within the NF- kB signaling pathway may be affected by these bacteria, possibly as the target of the bacterial T3SS. The modulation of the larval immune system in response to pathogen challenge should be further investigated in order to elucidate the exact mechanisms that are involved.

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