Bioactivity of black soldier fly larvae meal

Authors used cell-based in vitro assays to compare the immunogenic and anti-inflammatory capacity of whole and expeller-pressed black soldier fly organic insect meals to fishmeal, cricket powder and quercetin (a plant-derived anti-inflammatory). This is 14-day-old larvae. Photo: Collected

Determining in vitro anti-inflammatory and immunogenic capacity

The use of insect meal, mainly derived from larvae of black soldier fly (BSF, Hermetia illucens) as an aquafeed ingredient is under investigation while being increasingly adopted by the aquafeed industry. Most research has focused on the potential of insect meal as an alternative protein ingredient for several fish species – including rainbow trout, salmon, carp, sea bass and catfish – while only a few studies have investigated the immunological benefits of insect meal.

Here we present the results of a project aimed at investigating the in vitro immunogenic (or pro-inflammatory) and anti-inflammatory capacity of BSF organic black soldier fly meal compared to other commercially available ingredients.

Study setup/Ingredients tested

Descriptions of the ingredients investigated throughout this project are included in Table 1. All samples were dissolved in water, mixed at room temperature for one hour, and centrifuged to separate soluble (supernatant) from insoluble (pellet) material. The supernatant, containing soluble components, was 0.22 µm filtered and stored at minus-20 degrees-C until needed for cell assays.

Cell-based assays

The RAW264.7 mouse macrophage cell line was grown in vitro to produce nitric oxide (NO), a signaling molecule that plays a vital role in the pathogenesis of inflammation. Stimulation of NO production represents immunogenic or pro-inflammatory responses while decreased NO production suggests anti-inflammatory activity. RAW264.7 mouse macrophage cells were grown to produce two different cell-based assays.

Immunogenic (pro-inflammatory) capacity in vitro

To stimulate the production of NO and observe any immunogenic (or pro-inflammatory) responses, cells were treated with bacterial lipopolysaccharide (LPS) or the test ingredients. To ensure that any treatment effect was not related to toxicity (that could result in false positives), cell viability was measured in the assay in response to all project samples and ranged from 106–124 percent (expressed as a percentage compared to untreated cells).

The following methodology was followed: