Black Soldier Fly: A Bio Tool for Converting Food Waste into Livestock Feed

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Marwa Shumo
Black soldier fly larvae.

A rise in the global human population at the rate of 75 million annually, paired with rising living standards in emerging economies are causing an increase in global food demand. This is particularly pertinent for animal protein, for which demand is expected to grow by 70 percent by the year 2050. In addition to traditional systems, the ever-increasing demand is currently met by a constant expansion in intensive and modern livestock production systems. However, depending on current agro-ecosystems to meet this demand is environmentally challenging when one considers the over-exploitation of fertile lands, water resource scarcity, and cutting down of forests.

 

For example, it is estimated that one billion people in South Asia and sub-Saharan Africa depend on livestock production alone for food and livelihoods.1 However, livestock production occupies the largest share of agricultural land used for either grazing or growing feed crops, which could be used for growing foods for direct consumption. It also emits the highest amount of greenhouse gases (GHG) through enteric fermentation and manure production in comparison to other sources of GHG emissions, and thus plays a significant role in climate change. Livestock production can also negatively affect natural resources such as land, water, and biodiversity that are already subject to degradation and climate change. Therefore, there is a need to find alternative methods to increase agricultural production other than intensifying the use of current ones. It is possible to find a solution for livestock feed other than increasing the amount of lands used for growing feed crops.

 

On the other hand, around one third of total annual global food production at both pre- and post-consumption stages is wasted, and vegetables and fruits accounts for almost half of that waste. Pre-consumption in the form of postharvest loss account for around 40 percent of food lost in the developing world. This is mainly due to poor infrastructure, harvest facilities, transportation, and lack of farmers’ support. On the contrary, nearly half of food losses in the developed world occur at retail and consumer levels due to quality standards that overemphasize appearance.2

Marwa Shumo
A black soldier fly bioconversion chamber.

Traditional efforts are normally applied to produce compost and animal feed from food waste. However, these efforts depend on slow thermodynamic processes of either composting or depending on farm animals that are capable of feeding on food wastes and reprocessing them into manure. Bioconversion—the process of converting food waste into insect larval biomass and organic residues—can be an alternative to these inefficient traditional practices.3

 

There are various reasons to favor bioconversion over traditional waste management processes. Bioconversion reduces the amount of organic material by biological processing agents such as microorganisms or enzymes that transfer organic material into usable products or energy sources thus providing greater spatial potential for landfills and waste containers. In addition, waste reduction limits odors associated with landfills and waste sites, preventing the accumulation of unwanted material on solid surfaces that are associated with recyclables and the blockage of sewer pipelines by solid wastes. Bioconversion also limits methane production due to the anaerobic degradation of organic materials in landfills and waste sites.4 Furthermore, bioconversion is a natural process that can be used and adapted within households, bringing down the costs related to the transport and recycling of waste.

 

As a food source, insects contain high quality protein, vitamins, and amino acids. They have a food conversion rate that requires up to six times less feed than livestock for the production of the same amount of protein. In addition, they emit less greenhouse gases and ammonia than traditional livestock and can be reared on organic waste. Insects are thus a potentially powerful source for direct human consumption as food or indirectly as a protein source in livestock feed meal mixtures.

 

I work with a group of researchers who are exploring various insects for food and feed and targeting small farmers who not only can decompose their organic waste in an environmentally friendly way, but can also invest in crop production for direct human consumption, rather than livestock feed. My main research looks at the use of black soldier flies (Hermetia illucens) (BSF) for feed production and as a potential candidate for the bioconversion of organic waste. BSF are particularly interesting, as they efficiently convert various organic wastes into high-profile protein through decomposition, have global distribution, including moist tropic and subtropical regions, and can tolerate extreme temperatures.5–8

 

BSF have been used for waste management within the context of bioconversion, and they can also make use of various nutrients abundant in waste streams.9 In particular, their larvae can reduce a significant amount of food, animal, and sewage waste. Furthermore, they are not pests and actually deter the common houseflies that are normally linked to waste and low hygiene and health standards.10–12 BSF are not known to be vectors of any disease linked to animal or human health, unlike other insects such as the common housefly or mosquitoes. In addition, BSF can be used as a food protein source. When compared to livestock products, they exhibit some advantages. One is that they are cold-blooded and thus can convert feed much more efficiently into edible product. In addition, they produce less ammonia and GHG than traditional livestock, and occupy less space physically.13

 

Although this field of research is still in its infancy, studies have indicated that BSF have the ability to inactivate and reduce harmful microbial contaminants present in waste samples by modifying waste’s microflora.14

Marwa Shumo
Adult black soldier flies.

BSF also showed some potential in reducing heavy metal traces by incorporating and concentrating nutrients from waste samples into livestock feed. This reduces the waste’s nutrient concentration and bulk, thereby reducing the pollution potential by 50 to 60 percent or more.

 

The remaining BSF-decomposed waste can be used as a biocompost that can be readily applied to agricultural lands. This can also act as a solution to replace the use of chemical fertilizers, which can deplete soil if applied in excessive amounts and are costly.

 

Insect meal is a food product prepared by drying and pulverizing insects, and is proven to promote food assimilation and growth in animals. It is also rich in animal protein and vitamins. It can substitute for the costly components of fishmeal, soymeal, and grains that are added to livestock feed in order to promote food assimilation and growth in animals.15 Insects like BSF are good candidates because of their ability to efficiently transform waste into high protein products. Yet, there are many challenges to be addressed regarding their use, such as the ability to harvest these insects in a sustainable way while also meeting global demand. Until now, edible insects have been collected from nature and their potential future use as feed meal will require large-scale production. Therefore, methods to produce insect meal should be developed in a way to meet the rising demands sustainably. In addition, legislation on their production and use needs to be developed and food safety matters addressed.

 

Ultimately, edible insects provide a promising future source for animal protein. In particular, the BSF show a great potential in providing us with livestock feed by utilizing organic waste in an environmentally sustainable fashion.

 

Acknowledgments

This research was carried out under the supervision of Dr. Christian Borgemeister, Dr. Sunday Ekesi, Dr. Isaac Osuga, and Dr. Fathyia Khamis, and is funded by the INSEFEED program at ICIPE and its donors: International Development Research Centre (IDRC) and Australian Centre for International Agricultural Research (ACIAR).

 

References

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  14. Erickson, MC, Islam, M, Sheppard, C, Liao, J & Doyle, MP. Reduction of Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis in chicken manure by larvae of the black soldier fly. Journal of Food Protection 67, 685–690 (2004).
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