Performance of Black Soldier Fly on Vegetable Residue: Speculation on Diet Formulations

Today, I would like to review an article that passed across my desk recently. I must admit the timing was perfect as I was just in the Netherlands a week ago visiting colleagues at Wageningen University. I had the opportunity to meet Joop (one of the authors of the paper) in person. We had a great discussion about the BSF and future research opportunities.

The best part was that he gave me a copy of Dr. Barragán-Fonseca's dissertation!! I now have it on my shelf with other texts on insects as food and feed. I will gladly share it with other students conducting such research as it is a great example of a dissertation well done! The reason that it is exciting is due to the quality of her research, which I reviewed a few posts ago, and I bring it up because the paper I am reviewing today is from her PhD research.  I digress.... :)

As a side note, I am always glad to see students carry their work across the finish line and publish it for the world to read. What a great benefit for us all- to have these data to guide us along the path of mass production of the BSF. I encourage all students to do so (publish). Digressing continues....  Apologies. :)

The article for today's post is:

Barragán-Fonseca, K., J. Pineda-Mejia, M. Dicke, and J. J. A. van Loon. 2018. Performance of the black soldier fly (Diptera: Stratiomyidae) on vegetable residue-based diets formulated based on protein and carbohydrate contents. Journal of Economic Entomology 50: 898-906.


We know from previous work (see link for review of article previously discussed in blog) that protein:carbohydrate ratios impact BSF development. The study reviewed today explored this topic from a real-world perspective where one considers the variability associated with vegetable waste (or any sort of food by-product) rather than a chemically formulated diet. The authors conducted two experiments.

Experiment 1:
The authors formulated diets containing distiller's grain with grape pulp, potato peels, been seeds, cabbage leaves, and old white bread. All materials were homogenized before mixing. The goal was to formulate a diet at 47% P+C and P:C ratio of 1:2. 

Experiment 2: 
In this experiment, they worked with vegetable waste diets at 30% carbohydrate and 17% protein. The authors provide a table that summarizes the nutritional breakdown of the vegetable waste streams used in the experiments. 

Overall experiment design:
The authors used 100 larvae (<24 hr old at time of use) in a 750 ml container (well replicated across both experiments). If I read the article correctly, the authors did a single feeding (1 g dry matter per larva). Basic life-history traits were measured, such as larval development time, survival rate, and final larval weight. 

Findings:
Diet impacts production- simply put.  Diets higher in carbohydrates resulted in greater larval performance. But, this aspect of the diet is just one factor. The authors suggest amino acid composition could be playing a critical role as well. So, diets deficient is a "keystone" or "bottleneck" amino acid could be the difference be optimal and suboptimal production. 

One thing to consider:
Because these small factors (e.g., amino acid composition) can impact BSF development, you might consider using resources available that provide you some data on their nutritional makeup. For example, in the USA, the United States Department of Agriculture provides nutritional assessments of a number of possible vegetable or other organic waste streams.

Author

Jeffery K. Tomberlin, PhD, Impressed by Wageningen Research
Director, EVO Conversion Systems
​Twitter: @FliesFacility