Impact of pH and feeding system on black soldier fly (Hermetia illucens, L; Diptera: Stratiomyidae) larval development

Abstract

Black soldier fly (BSF) is a generalist species able to reduce large quantities of organic substrates and is thus considered as an interesting solution for waste management. Moreover, as BSF larvae accumulate high quantities of nutrients during their growth, they are valued because of their potential to produce products such as protein meal or fat for livestock feeds. Abiotic factors can influence larva growth, and a more detailed knowledge and control of these parameters can lead to the development of mass BSF breeding for the production of innovative products for animal feeds. As little information is available on the effects of the pH of substrates and feeding systems, the aim of this study was to evaluate the impact of these two factors on the activities of BSF larvae, prepupae, and adults. An experiment was performed with two fixed factors: i) pH (4.0; 6.1; 7.5; 9.5) and ii) feeding system (batch feeding system (TFS) or daily feeding system (DFS)). The pH treatments impacted larval weight on the first, third, and fifth day, but not at the end of the trial. Larval activity increased pH values from the fourth day onward, with final values of around 8.9–9.4 in all the treatments. The weight of the prepupae ranged from between 0.094 and 0.100 g. The final weight of the larvae and pupae, sex ratio, ingested food, larval mortality, percentage of emergence, and time to reach the pupa stadium were all affected by the feeding system. DFS showed the heaviest final larval weight (0.149 g), but required a longer time (11.3 d) than TFS to reach the prepupa stadium. The findings of this research could be useful for the mass production of BSF. Evaluation of an appropriate feeding system and initial pH value of the substrate are important parameters to reduce the time and to increase the weight in the production of larvae.

Comparing Selected Life-History Traits of Black Soldier Fly (Diptera: Stratiomyidae) Larvae Produced in Industrial and Bench-Top-Sized Containers

“…Under more natural conditions, black soldier fly larvae occur at high larval numbers in dung piles ( Sheppard 1983 , Fatchurochim et al 1989 ) or carrion ( Tomberlin et al 2005 ), which are normally associated with unpredictable pathogen levels ( Diclaro and Kaufman 2009 ). The ability of black soldier fly larvae to modify pH ( Ma et al 2018 , Meneguz et al 2018a ) can result in suppressed pathogens ( Wang et al 2015 ) and improve the palatability of the food ( Deshpande et al 2015 ). Furthermore, black soldier fly larvae produce antimicrobial peptides that can inhibit a broad spectrum of bacteria ( Park et al 2014 , 2015 ; Vogel et al 2018 ), and studies have shown that black soldier fly larvae can reduce Escherichia coli ( Erickson et al 2004 , Liu et al 2008 ), Salmonella spp.…”

A comprehensive dynamic growth and development model of Hermetia illucens larvae

“…The function r assim max represents the ingestion/feeding potential of the larvae in relation to it its current size and the maximum size it can reach when infinitely fed. With this Eq (17), a relation between the development sum and the size dependent ingestion is established. Maturation stage.…”

“…Finally, the regulation function for development rate r dev can be modelled similarly to Eq (17), a function of all factors affecting development, as…”

“…The influence of diet, its moisture content and the temperatures were studied together to showcase its importance in the development of the larvae [13][14][15][16]. Another study [17], proposed and showed the effects of pH levels of the substrate (feed), in which larvae are grown, on the larval development. From these studies, one can conclude the importance of the environmental conditions (temperature, humidity, etc.…”

Lipid profile and growth of black soldier flies (Hermetia illucens, Stratiomyidae) reared on by‐products from different food chains

“…In the last few years, this species has been used in different studies for waste bioconversion . Indeed, BSF larvae are extremely voracious as well as highly suitable for being fed different organic wet substrates (with wide pH and moisture ranges), including by‐products originating from the food industry, agricultural and livestock processes, municipal garden waste, and household food scraps …”