Fate of Hexabromocyclododecane (HBCD), A Common Flame Retardant, In Polystyrene-Degrading Mealworms: Elevated HBCD Levels in Egested Polymer but No Bioaccumulation

Abstract

As awareness of the ubiquity and magnitude of plastic pollution has increased, so has interest in the long term fate of plastics. To date, however, the fate of potentially toxic plastic additives has received comparatively little attention. In this study, we investigated the fate of the flame retardant hexabromocyclododecane (HBCD) in polystyrene (PS)-degrading mealworms and in mealworm-fed shrimp. Most of the commercial HBCD consumed by the mealworms was egested in frass within 24 h (1-log removal) with nearly a 3-log removal after 48 h. In mealworms fed PS containing high HBCD levels, only 0.27 ± 0.10%, of the ingested HBCD remained in the mealworm body tissue. This value did not increase over the course of the experiment, indicating little or no bioaccumulation. Additionally, no evidence of higher trophic level bioaccumulation or toxicity was observed when L. vannamei (Pacific whiteleg shrimp) were fed mealworm biomass grown with PS containing HBCD. Differences in shrimp survival were attributable to the fraction of mealworm biomass incorporated into the diet, not HBCD. We conclude that the environmental effects of PS ingestion need further evaluation as the generation of smaller, more contaminated particles is possible, and may contribute to toxicity at nanoscale.

Enhanced Bioavailability and Microbial Biodegradation of Polystyrene in an Enrichment Derived from the Gut Microbiome of Tenebrio molitor (Mealworm Larvae)

“…Mealworms, larvae of T. molitor Linnaeus (average weight: 75–85 mg/worm), were purchased online from Rainbow Mealworms (Compton, CA) and shipped overnight to the laboratories at Stanford University (mealworms from this source have previously been shown to degrade PS). ,,, Prior to arrival, the mealworms were fed bran; after arrival, they were subject to a 48 h starvation period before initiating tests with the experimental diet of either natural wheat bran (Exotic Nutrition, Newport News, VA) or PS foam. Mealworms (∼1200 per experimental condition) were bred in food-grade polypropylene containers (volume: 780 mL) and kept in incubators maintained at 25 °C and 70% humidity. , Each diet condition was duplicated.…”

Chemical safety of black soldier fly larvae (Hermetia illucens), knowledge gaps and recommendations for future research: a critical review

“…Currently, some insect species (Tenebrio molitor and Plodia interpunctella) are known to be capable of degrading plastics (i.e. polystyrene and polyethene) to a certain extent (Brandon et al, 2019;Yang et al, 2014Yang et al, , 2015aYang et al, ,b, 2018. While larvae of the Indian meal moths (P. interpunctella) appeared to be able to chew on and eat polyethene (PE) films, two bacterial strains capable of degrading PE were detected in their gut.…”

Plastics and the microbiome: impacts and solutions

“…Similarly, the 'consumption' of plastics by mealworms and wax moth larvae has gained much attention [30,145], but confirmation of plastic degradation by the hosts' gut-derived enzymes, independent of the hosts' microbiome, requires further confirmation [146]. In most cases, it remains to be seen whether the host derives any nutritional benefits from plastic as a source of energy; without stronger evidence of more complete degradation in the gut, plastic fragments may merely be generated via mechanical processes (e.g.…”