Black soldier fly larvae (BSFL) have been used as an alternative animal feed as they are a good source of protein and fat with comparable nutritional value as soybean. They can be grown on a variety of organic waste, including manure, kitchen waste, and rendered fish. However, when different substrates are being used for producing BSFL, chemical safety should be evaluated. Bioaccumulative organic contaminants such as pesticides and per-/polyfluoroalkyl substances (PFAS) posted public concerns for producing BSFL as animal feed, which eventually is consumed by humans. In this study, we produced BSFL using almond hulls and analyzed residual contaminants bioaccumulate and/or biotransform in BSFL. We firstly identified toxic, bioaccumulative, and/or persistent organic chemicals that are present in six almond hulls requested from local farms of California (2016-2017) by acquiring all-ion data-independent high-resolution mass spectra screening against an in-house chemical library (~ 5,000 unique structures). We secondly narrowed our quantitative analysis to only two almond hulls for the BSFL chemical uptake study. Esfenvalerate, cyhalothrin, and bifenthrin were the most abundant pyrethroids quantified (81.7 to 381.6 ng/g-dw) in the two hull types. Then, we dosed five PFAS in one hull type and we did not observe bioaccumulation of any legacy or emerging PFAS. However, we found that residual bifenthrin in both hull types bioaccumulates in BSFL. The concentration of bifenthrin in BSFL tissue is 36.2%-56.8% greater than the level in residual almond hull substrates. The present of BSFL for bifenthrin biodegradation is still under investigation. The survival rate of BSFL in all rearing studies was greater than 90%. Tissue-specific bioaccumulation will be further investigated to advise post-production processing scenarios. Separating the larvae into lipid and protein fractions could be beneficial for commercial applications and for managing detected bioaccumulative chemicals.

Emerging contaminants bioaccumulate and/or biotransform in a terrestrial insect- black soldier fly larvae (BSFL)

ACS Spring 2022

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