Influence of Temperature on Selected Life-History Traits of Black Soldier Fly (Hermetia illucens) Reared on Two Common Urban Organic Waste Streams in Kenya

Abstract

In sub-Saharan Africa, urban populations are projected to increase by 115% in the coming 15 years. In addition, economic growth and dietary shifts towards animal source foods have put high pressure and demand on agricultural production. The high ecological footprint of meat and dairy production, as well as high feed costs, prevent the livestock sector from meeting the increasing demand in a sustainable manner. Insects such as the black soldier fly (BSF) have been identified as potential alternatives to the conventionally used protein sources in livestock feed due to their rich nutrient content and the fact that they can be reared on organic side streams. Substrates derived from organic byproducts are suitable for industrial large-scale production of insect meal. Although efficient in waste management and in feed production, BSF larvae are very sensitive to the external environment such as temperature and rearing medium. Therefore, we studied the effect of temperature and substrate type, i.e., brewers’ spent grain (SG) and cow dung (CD), on the development and survival of BSF larvae. Both organic substrates were readily available in Nairobi, Kenya, the location of the experiments. In our experiment, 100 3–5-day-old BSF larvae were placed into containers that contained either SG or CD and further treated at temperatures of 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C. The duration of larval development was recorded, and the prepupae were removed, weighed, and placed individually in separate, labeled, 35-mL plastic cups filled with moist sawdust. After emergence, 10 2-day-old adults (5 males and 5 females) from every replica per substrate were transferred into a cage (40 × 40 × 40 cm) and allowed to mate for 24 h at their respective temperatures. The laid egg batches were collected and counted, and the adult flies’ longevity was recorded. The data were subjected to a two-way analysis of variance (ANOVA) using the general linear model procedure. BSF larvae reared on SG developed faster than those reared on CD; the former also favored higher temperatures for their larval development and emergence into adults. The optimum range was 25–30 °C. With increasing temperatures, the longevity of adult BSF decreased, while the fecundity of females increased. Thus, it is possible to take advantage of the readily available SG waste streams in the urban environments of Kenya to produce BSF larvae-derived livestock feed within a short duration of time and at relatively high temperatures.

A comprehensive dynamic growth and development model of Hermetia illucens larvae

“…The functions that are modelled in this work as cases or switching functions, Eqs (11), (12), (17) and (18), are realized as logistic functions in the actual implementation of the model in…”

“…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).…”

“…This insect species originates from tropical South American climate zones and thus requires a warm and humid environment. Such conditions were verified in research studies: [ 10 ] highlighted the threshold temperatures and thermal requirements; [ 11 ] compared the development rates over different temperature ranges; and [ 12 ] studied the effect of humidity on the egg eclosion and adult emergence. The influence of diet, its moisture content and the temperatures were studied together to showcase its importance in the development of the larvae [ 13 – 16 ].…”

Comprehensive Resource Utilization of Waste Using the Black Soldier Fly (Hermetia illucens (L.)) (Diptera: Stratiomyidae)

“…Insect growth and development are also affected by temperature, light, and humidity. Certain appropriates temperature (27.5–37.5 °C) [57,58], light levels [59,60] and humidity (70%) [61] are more conducive to spawning, emergence, and conversion of organic waste in this insect. Several studies have found that hydrolytic proteins and organophosphates from Bacillus subtilis are present in the gut and skin of H. illucens larvae [62,63].…”

Molecular identification and life cycle of Black Soldier fly (Hermetia illucens) in laboratory

“…The knowledge about life history traits and molecular biology of a species plays very important role to establish breeding industry and mass scale production. Additionally, previous studies have been supervised on life history traits of BSF on different substrates to utilize industrialization in temperate zone (Jucker et al 2017, Shumo et al 2019, Gobbi et al 2013. In this study, molecular identification using the barcode region of the mitochondrial cytochrome oxidase I (mtCOI) gene and life cycle of local species, H. illucens from Bangladesh were investigated under laboratory condition.…”