Influences of chromium and cadmium on the development of black soldier fly larvae

Abstract

The black soldier fly Hermetia illucens is a good candidate for waste management. The harvested insects are rich in protein and have the potential to be used in animal feed. However, people are wary about heavy metals in waste. Therefore, it is necessary to understand how the uptake of heavy metals could affect H. illucens and where and to what extent metals are accumulated by the black soldier fly. Based on these considerations, developmental parameters were investigated in the different life stages of H. illucens fed an increasing concentration gradient of cadmium (Cd) and chromium (Cr); additionally, Cd and Cr distribution in the body parts of H. illucens at the different life stages was monitored. We found that Cd and Cr have no effects on larvae survival and eclosion rate, but they do have effects on larvae duration and pupation rate. Both Cd and Cr were transferred into larvae, prepupae, and pupae. While the concentrations of Cd in larvae and prepupae were much higher than that in their diets, the opposite case was observed with Cr. The concentrations of Cd and Cr in H. illucens decreased in later development stages. In individual larva and prepupa, Cd and Cr were mainly included in the body and not in the integument. In the pupa, the puparium contained higher Cd and Cr concentrations than the pupa body. The distribution of Cd and Cr in the different life stages and body parts may present a potential strategy for how H. illucens tolerate and remove heavy metal stress.

Uptake of heavy metals and arsenic in black soldier fly (Hermetia illucens) larvae grown on seaweed‐enriched media

“…These findings concur with previous studies that provided feeding media spiked with Cd in increasing concentrations to BSF larvae. [35][36][37] In these studies, BSF larvae accumulated higher concentrations of Cd (up to ∼7 mg kg −1 , 37 and up to 170 mg kg −1 , 35 ) compared to this study (highest Cd concentration was 2.3 mg kg −1 ). This difference could be due to higher exposure levels of Cd used in these studies, or because spiked Cd was more available than Cd in the seaweed-enriched media.…”

“…In the current study, Cd levels in BSF larvae increased simultaneously to increasing concentrations of this metal in the feeding media. These findings concur with previous studies that provided feeding media spiked with Cd in increasing concentrations to BSF larvae . In these studies, BSF larvae accumulated higher concentrations of Cd (up to ∼7 mg kg −1 , and up to 170 mg kg −1 ,) compared to this study (highest Cd concentration was 2.3 mg kg −1 ).…”

“…For example, a recent study from Diener and colleagues indicates that Pb is mainly sequestered in the exoskeleton of BSF larvae, which can be removed during industrial processing of the larvae. Conversely, Cd seems to be found mainly in the larval body rather than in the integument . After processing, this metal would most likely end up in insect protein, due to its affinity to protein rather than fat in animal tissues.…”

“…However, very little data are available on these elements in farmed insects, e.g. mealworm ( Tenebrio molitor ) and BSF . Similarly, there are limited data available regarding the presence of these compounds in the feeding media currently used to rear farming insects.…”

“…mealworm (Tenebrio molitor) and BSF. [34][35][36][37][38] Similarly, there are limited data available regarding the presence of these compounds in the feeding media currently used to rear farming insects.…”