I have discussed in previous posts the importance of recognizing, "what you are is what you eat". I think most people recognize this statement for its value as related to another adage garbage in- garbage out. Basically, what you consume impacts your own health and nutrition. 

The same is also highly recognized for diet formulations for livestock, poultry, and aquaculture. Such information is critical for optimal production of a species in confined agricultural settings as well as the economics of the system.

With regards to BSF, we know what is fed to them as larvae impacts their own nutritional value in the end. For example, high carbohydrate diets (e.g., fruits) can result in increased fat content of the larvae. 

A study recently published by colleagues in the UK and Sweden in collaboration with Protix, Inc examined this from a slightly different perspective- specifically, the impact of the stage of the BSF (larva vs prepupa) as well as stage of processing (with or without fat) on the microbiome (the link is related to the microbiome of humans- but it gives a nice overview of the importance of such work) of fish being fed these materials.  Here is a link for a nice review article of microbiomes of marine fish.

The study in question is:

Huyben, D., A. Vidaković, S. W. Hallgren, and M. Langeland. 2018. High-throughput sequencing of gut microbiota in rainbow trout (Oncorhynchus mykiss) fed larval and pre-pupae stages of black soldier fly (Hermetia illucens). Aquaculture.

In the study, they used a control fishmeal diet and various combinations (ration of 70:30) of this diet with either BSF larvae; 1) control, 2) fishmeal with larvae, 3) fishmeal with defatted larvae, and 4) fishmeal with prepupae.

The major findings of the study were:
1- diet impact fish microbiome as it varied in fish across diets
2- data indicate using BSF could enhance some beneficial microbes to fish health

The data produced from this study are a great first step in understanding the trophic (layers) interactions between diet, consumer, and associated microbes. I think there is tremendous opportunity here to unite disciplines (as demonstrated by the diversity of authors on this paper) and figure out the appropriate feed formulations and benefits/restrictions of using such diets.

A couple of questions that come to mind from this study are:
1- What was the microbiome of the insects being used (did any of these microbes proliferate in the fish)?
2- What specifically were the insects fed when being produced for the study?
3-BSF produced by Protix were reared on a different diet than those produced by the researchers. Could this be a confounding factor impacting results (i.e., microbiome)?
4- How does shifting larval diet impact their microbiome and does this translate into impacts of the fish microbiome?
5- I recognize limitations of taxonomic resolution (i.e., clarity of identification and data interpretation), but are there microbes specific to fish that engage in gene transfer with microbes from the insects (i.e., do the microbes merge genetically)
6- Was there an assessment of antibiotic resistant genes in the insects before use and could this impact the fish microbiome?

These are questions resulting from reading the study which could be investigated in the future. I believe the authors laid a wonderful foundation on which to build additional research. 

I had a great visit with colleagues and friends from Malaysia and Italy this past week. All came to learn more about the mass production of the BSF and the science being conducted to optimize the process. 

WK & Thomas, from BETSOL in Malaysia, are currently developing sites for waste management and protein production. 

Francesco and friends from the Instituto Zooprofilattico Sperimentale Lombardia ed Emilia-Romagna were learning about mass production as well as the research being conducted to optimize the process.

What was really nice, besides discussing BSF, was the continued development of the BSF network around the world.

As many of you know, I lead a duel life with one part of career being devoted to research. My laboratory focuses on decomposition ecology as related to a number of topics including the BSF.

​Over the course of the past couple of years I have worked with several of my colleagues (Jibin Zhang and Minmin Cai) on the relationship between antibiotics in wastes and their impact on BSF production. We had a publication come out a little while back that demonstrated BSF and their companion microbes actually degrade the antibiotic tetracycline in waste- which is great news for remediation of associated concerns.

You can learn more about antibiotics in the environment through this Science News and associated scientific review on the topic.

The first paper we published (as previously mentioned) is:

Cai, M., S. Ma, R. Hu, J. K. Tomberlin, C. Yu, Y. Huang, S. Zhan, W. Li, L. Zheng, Z. Yu, and J. Zhang. 2018. Systematic characterization and proposed pathway of tetracycline degradation in solid waste treatment by Hermetia illucens with intestinal microbiota. Environmental Pollution 242: 634-642.

As a followup to this previous work, we just had a second paper published demonstrating the frequency of antibiotic resistant genes (ARGs) in the microbial community remaining in the waste after digestion is reduced.

Cai, M., S. Ma, R. Hu, J. K. Tomberlin, L. S. Thomashow, L. Zheng, W. Li, Z. Yu, and J. Zhang. Rapidly mitigating antibiotic resistant risks in chicken manure by Hermetia illucens bioconversion with intestinal microflora. Environmental Microbiology 0.

More specifically we demonstrated:
1. non-sterile BSF reduced ARGs by 95%.
2. remaining bacteria, which was primarily Firmicutes had a 65% reduction in ARGs.
3. human pathogen populations declined by 70-92%.
4. conditions of the substrate impacted the ability of BSF to have this impact.
5. bacteria associated with BSF most likely play a role in this process (it is not just the BSF).

These data are tremendous as they demonstrate other benefits of using BSF to recycle animal wastes- not just food wastes.

I recently received an email from my colleague and friend, Professor Arnold van Huis regarding a report issued by the Council on Animal Affairs (hence the title of the post) in the Netherlands.  There are two summary sections from the council. The first section provides an overview of the content presented in the section second.

The Emerging Insect Industry: Invertebrates as Production Animals

Topics reviewed include:
-An overview of insect production in the Netherlands
-Legislation and regulations
-Research and Education in the Netherlands
-International Aspects
-Relevant social values
-Conclusion

The report serves as a suitable model for other government agencies around the world to consider when determining proper legislation and management of the insects as food and feed industry. I found all sections interesting. But, the two that really stood out to me were the discussion with regards to food/feed safety and animal welfare; two areas we are still needing to focus a bit of time culturing and developing.  

If you get a chance, check them out and offer comments. I would be interested in knowing what you think.

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.

I enjoy reading research papers published by established colleagues and friends throughout the world. But (no offense to my colleagues), my excitement for their work pales in comparison to reading theses or dissertations of students. Their work demonstrates the promise such individuals have to the industry as a whole.  

I guess some could say it is a compliment to my established colleagues that I find their students' work so exciting. These individuals (the students) invest so much to conduct the research and organize it into a coherent story for us to read. 

So much promise- so much potential!   

Of course, none of it would be possible without the guidance of the advisor - so many thanks to you as well for your hard work and dedication.

The MS thesis I would like to review today is by a friend and colleague- Devon Brits who is currently seeking his PhD at Louisiana State University (love your dedication, Devon).  

I believe the thesis is accessible at the following link: 

Improving feeding efficiencies of black soldier fly larvae, Hermetia illucens (L., 1758) (Diptera: Stratiomyidae: Hermetiinae) through manipulation of feeding conditions for industrial mass rearing

The thesis has five chapters. The first is the literature review and the last is the conclusion. So, Devon completed three research projects for his MS (quite impressive).

Chapter 2 examined the impact of food availability, feeding depth, and particle size on the development and feeding efficiency of the BSF larvae. All factors were found to impact BSF larval development. Feeding depth less than 10 cm was optimal for feed conversion; however, larvae developed significantly faster when feed at a depth < 5 cm. The impact of particle size was variable. But, I think it is important to know such work is critical for mass production. How should feed be prepared and provided? Particle size surely has an impact as surface area dictates access to the feed.

Chapter 3 examined the impact of feed rate at a set density on BSF mass-rearing. Basically larvae should have access to 125-200 mg/larva/day. Such results would of course be population specific. Furthermore, feed type will have an impact on the development of BSF larvae as well. One thing noted in the chapter is the need to carry this work to the next stage. If larval size is impacted by feed rate and feed quality, what is the impact on resulting adults and their mating success? 

Chapter 4 examined different larval densities (scale) on feed conversion. This experiment is really nice as the larval number ranged from 5 to 50,000 per replicate/treatment (yes, you read that correctly). Feed was provided at 2.12g/larva (feeding was done twice during the experiment).  Major finding relate to mortality being high during initial two instars (something to think about). Data generated for lower density were consistent with previously published work. But, as the density increased to more industrial scale, data were quite different- for example, bioconversion rates were slightly higher.

These data call into question the value of bench top versus industrial scale research. I highly recommend students to consider integrating industrial scale work with their bench top studies (or vice versa) as both data types are crucial for industrial development.


Overall: Great job, Devon. Very impressive work and a serious contribution to the BSF community. I encourage everyone to take a look at his work and cite it in your research- it is quite valuable!