Cold Hardiness of the Black Soldier Fly (Diptera: Stratiomyidae)

Abstract

The black soldier fly, Hermetia illucens (L.), shows potential as a resource for animal feed. However, industrial production in regions where the insect is not native, like northwestern Europe, could lead to permanent establishment, which might entail environmental risks. In temperate climates, establishment depends on the insect's ability to overwinter. This study assessed the insect's cold hardiness by determining the supercooling point (SCP) and lower lethal time at 5 °C (LTime10,50,90) for different life stages. As diet or acclimation can influence cold hardiness, prepupae reared on different substrates and acclimated prepupae were tested in separate experiments. The SCP ranged from -7.3 °C for late-instar larvae to -13.7 °C for pupae. Prepupae reared on a highly nutritional substrate had a lower SCP compared with a control diet composed of chicken feed (-14.1 °C vs. -12.4 °C, respectively), whereas the SCP was unaffected by acclimation. Based on the LTime, prepupae and pupae were the most cold hardy life stages. Acclimated prepupae were most cold tolerant, with a LTime50 of 23 d. Based on an empirical relationship between LTime50 and field survival of various arthropods, it was predicted that H. illucens would survive about 47 d in the field during northwestern European winters. The results from this laboratory study suggest that H. illucens is rather unlikely to overwinter in northwestern Europe. However, caution is warranted given that diet and acclimation can influence the insect's cold hardiness and in the field the insect may survive in a diapausing state or in protected hibernacula.

Cold acclimation ofTrogoderma granariumEverts is tightly linked to regulation of enzyme activity, energy content and ion concentration

“…In prepupae of Hermetia illucens (L.) (Dip. : Stratiomyidae), the SCP was unaffected by cold acclimation, but cold hardiness increased in compared to control (Spranghers et al, 2017).…”

Approaching Ecological Sustainability in the Emerging Insects-as-Food Industry

“…The risk of commercial insect species becoming locally invasive should not be easily discounted, especially since the cost of invasive species to natural and production systems are enormous (an estimated 14% reduction in global food production as a result [38,39]). Even where species like the black soldier fly Hermetia illucens seem unlikely to establish based on extrapolation from laboratory experiments [40], there is mounting evidence that they could, in fact, establish in these and other areas under certain conditions [40][41][42]. The precautionary principle should be exercised regarding non-native species, unless there is solid scientific evidence to suggest otherwise, especially with climate change making the establishment and spread of many non-native species more likely [43].…”

The puzzling mitochondrial phylogeography of the black soldier fly (Hermetia illucens), the commercially most important insect protein species

“…However, the evidence is not entirely conclusive because BSF flies, prepupae, and pupae are resistant to cold and can survive low temperatures (5°C) for several weeks [34]. This may explain why there is an established BSF population in Northwestern Switzerland that has been regularly encountered for one decade.…”