Threshold temperatures and thermal requirements of black soldier fly Hermetia illucens: Implications for mass production

Abstract

Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers’ yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10–42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4°C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0°C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (rm = 0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models.

A comprehensive dynamic growth and development model of Hermetia illucens larvae

“…To evaluate the model presented in Eq (10), for influence of moisture on the growth, a total of three data sets M1-M3 were obtained. M1 and M3 are results published in [19] and [35] respectively.…”

“…Such information could be used to deduce requirements, in mass production context, for designing suitable reactors. Similarly, feed density and moisture models, Eqs (9) and (10), could be useful in preparing the feeding regimes and feed recipes for either better growth rate and reduced larval mortality or for better waste processing. The dynamic model, Eqs (4) and (5), serve as tools to compute dynamic information pertaining to the larvae growth and development.…”

“…A total of four data sets (T1-T4) representing the influence of temperature on larvae development was obtained from [10,11]. These four data sets represent the temperature dependency under four different feed types and was used to obtain the parameters for models Eqs (6) and (7).…”

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

“…One way or another, it appears likely that BSF will be able to increase its current range as global warming takes hold. We would suggest that urban populations will most likely spearhead the range expansion because they bene t readily available organic waste and bene t from higher temperatures in urban environments [32]. Range expansion may also be facilitated through population homogenization as more cultures are shared over long distances and escaped ies cross-breed with native or previously established non-native populations.…”

“…Arguably, the most convincing evidence for human-mediated introductions come from specimens collected at latitudes that are unlikely to support breeding populations [13,29,30,31]. The lower threshold for BSF larval survival was observed to be 15-19 °C depending on study [32,33], and some Canadian BSF localities are unlikely to meet this requirement. Marshall et al [13] thus hypothesized that the annual occurrence of BSF in Ontario (Canada) is due to the disposal of unused shing baits (larvae) by local shermen or the accidental release of ies into nature by owners of pet reptiles.…”