Diet is one of the most widely studied topics in BSF literature. So many articles—so many different diets. The information can be overwhelming, but the bottom line is that diet impacts growth and development. You may be thinking, well, that’s a no-brainer.
We have seen countless times that if we feed BSF a low-quality diet, we can expect prolonged development, reduced larval weights, and reduced survivorship, etc. But, do you know why this occurs?
Metabolism is key—the feed we give BSF is either assimilated into new biomass or is utilized to generate energy. I recently found a new BSF publication that investigated how diet quality effects metabolic performance and the findings lend insight as to why poor diets result in reduced growth and development. I have included the citation below if you wish to look up the paper for specific details about the study.
To summarize the results, Laganaro et al. (2021) found that larvae fed a low-quality diet sustained their maximum growth rate for less time than those fed a high-quality diet. So, on the surface, when we feed low-quality diets, we see delayed development and small larvae, and one of the reasons is because the larvae are not meeting their maximum growth rate for the same amount of time as they would if they were fed a more nutritious diet. Why?
Because of the demand for maintenance purposes. Larvae fed a poor diet have higher energy requirements and higher CO2 respiration, so more of the feed is lost to energy production and respiration; therefore, less is available for new biomass. And collectively, this slows the growth rate and results in smaller larvae.
Although BSF are generalist feeders, the authors make an important statement worth noting, and that is that feed conversion into new biomass is substrate specific. In other words, as Jeff Tomberlin once told me, “Not all diets are hot dogs”—meaning the composition of diets differ and the ability of BSF to convert their feed will vary. I wondered after he said that when and where I would use that little nugget of knowledge, and I think I found the perfect place.
The take home message is if your larvae are developing slow and are small, and you are looking for ways to change this, a good starting place is to go back to the basics and evaluate your diet.
This makes me think: if only junk food would keep me young and skinny…
Laganaro, Marcello, Simon Bahrndorff, and Niels Thomas Eriksen. "Growth and metabolic performance of black soldier fly larvae grown on low and high-quality substrates." Waste Management 121 (2021): 198-205.
Chelsea Miranda, PhD
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Individuals with over 25 years research experience with the black soldier fly. We are passionate about the science behind the black soldier fly and its ability to convert waste to protein.
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