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Black soldier flies: A cheap source protein for animal feed, fertiliser

Black soldier fly.
Black soldier fly.
Black soldier fly larvae.
Black soldier fly larvae.

Black soldier flies could cut cost of feeds to farmers because it is a cheaper alternative source of protein. The fly feeds on waste and lays eggs, which when they become larvae, they could be crushed to make fish and livestock feed. Also, their droppings are organic fertiliser.

Black soldier fly is most useful at the larvae stage. The larvae, or maggots can eat a wide range of food waste and other waste materials. The larvae eat common waste such as food, rotten vegetables, and fruits, as well as human waste.

The larvae quickly convert the waste into protein.

From hatching, black soldier fly larvae only take 10-14 days to grow fully. At this adult stage, the larvae are fed to animals, providing a protein-rich food source for livestock. Alternatively, the larvae are harvested, dried and ground.

Black soldier flies are renowned as being one of the most efficient waste recyclers of the insect world.

Australian government’s Australian Centre for International Agricultural Research says that unlike common houseflies, black soldier flies don’t have mouths. So, they are incapable of transmitting deadly diseases, posing minimal risk to human or animal health.

Black soldier fly lifecycle. Black soldier fly is most useful at the larvae stage. (By Journal of Environmental Management)
Black soldier fly lifecycle. Black soldier fly is most useful at the larvae stage. By Journal of Environmental Management.

“Adult black soldier flies have one goal—to lay eggs,” says the centre.

Meru University of Science, Kenya, has a project that uses black soldier fly to eat human waste resulting in organic fertiliser and animal feed from the larvae.

Mr Simon Irungu, a researcher at the university, said the fly helps cut food waste but also gives animal feed. He said that ground larvae contain up to 45 per cent protein and 37 per cent fat.

Using black soldier fly to make fertiliser

There’s another benefit from the black soldier fly. As the larvae feed on the waste, their droppings are collected to be used as organic fertiliser.

When fed organic waste, black soldier flies produce nitrogen-rich insect manure that can be used as a high-performing fertiliser.

Mr Irungu said the organic fertiliser has no disease, but rich in nitrogen, potassium, and phosphorus. “The bio-fertiliser is a good soil conditioner with high water retention capacity,” he said.

Dr Chrysantus Tanga, a research scientist at International Centre of Insect Physiology and Ecology (Icipe) in Nairobi, says black soldier flies cut time taken to make organic fertiliser by about four times. It takes black soldier flies five weeks to make organic fertiliser. But using other methods to make organic fertiliser takes between eight and 24 months.

Dr Tanga and his research team tested black soldier fly fertiliser on maize in an open field. They found that plots where black soldier fly fertiliser was used had 14 percent higher maize harvest than plots that used commercial organic fertiliser.

READ: UNEP: Government must tax chemical fertilisers and pesticides

How Meru University gets black soldier fly larvae

Meru University of Science and Technology (MUST) hosts a farmer’s day at its Sanitation Research Institute. The institute’s director, Dr Joy Riungu, holds a grooved ring where black soldier flies lay eggs. The university shows farmers how to use black soldier fly on waste to make poultry feed.
Meru University of Science and Technology (MUST) hosts a farmer’s day at its Sanitation Research Institute. The institute’s director, Dr Joy Riungu, holds a grooved ring where black soldier flies lay eggs. The university shows farmers how to use black soldier fly on waste to make poultry feed.

Meru University of Science and Technology feeds black soldier flies with human waste to get animal feed and organic fertiliser.

The university collects human waste from the nearby Kunene primary school. The school’s toilets are designed to separate urine from faeces. The faeces are collected and carried to the university to be treated. Also, the university collects food and vegetable waste from its campus.

At the university the waste is weighed and checked to remove all things which cannot rot. The waste is then taken inside a well-ventilated house and spread evenly onto the trough.

Five days old old black soldier fly larvae are put into the waste. They start eating the waste.

The university harvests fertiliser and larvae after between 10 to 14 days. The larvae are dried and ground to be protein for animal feed.

To ensure the university has enough larvae, it allows some larvae to grow to pupa, which hatch to flies. The flies lay eggs, which hatch to larvae that eat waste.

How black soldier fly became the favourite source of protein

Roseanne Mwangi (right) collecting mature black soldier fly larvae that will be dried and used as animal feed.
Roseanne Mwangi (right) collecting mature black soldier fly larvae that will be dried and used as animal feed.

The Rockefeller Foundation worked with International Centre of Insect Physiology and Ecology (Icipe) to increase animal feed from insects for poultry and pigs in Kenya.

The centre studied more than 28 insect species, including locusts and crickets. It chose black soldier fly larvae as the best option. Dr Chrysantus Tanga, a researcher at the centre, said black soldier flies were exceptional.

“Our research showed the BSF [black soldier fly] larvae are even better for the animals than conventional feed,” Dr Tanga said. “Scaling up insect-based technologies will have a huge impact in improving poultry, fish and pig production.”

That means better quality meat and eggs, and faster to market, he said.

Ms Rosanne Mwangi, who makes and uses larvae to make feed, says her roaming chickens are now ready to be sold after 16 weeks. This is eight weeks earlier than before she started feeding them black soldier fly larvae. And her pigs are ready for market in about six months, saving her one to two months.

The Rockefeller Foundation said the larvae had the advantage of being used solely as animal food. Traditional feed is made from fish and soyabeans, and the animals are in a sense competing with humans for this food, the foundation said.

“And finally, BSF [black soldier fly] production creates job opportunities for youth and women who produce the feed,” the foundation said. “[Ms] Mwangi employs seven people fulltime and brings in extra workers during peak harvesting periods.”

Young Tanzanians use organic waste to make fish feed

Ms Catherine Fizidoline, a co-founder of Samaki Farms, prepares organic wastage at a workshop in Dar es Salaam, Tanzania. Photo by Xinhua.
Ms Catherine Fizidoline, a co-founder of Samaki Farms, prepares organic wastage at a workshop in Dar es Salaam, Tanzania. Photo by Xinhua.

Six young aquatic and fisheries science graduates from Tanzania’s government university are saving fish farmers the difficulties of getting suitable fish feeds.

Mr Arnold Shoko, one of the founders of Samaki Farms, said they were solving two problems. They are using black soldier flies to change rotten vegetables and fruits to protein for fish feed.

“We offer ingredients to fish farmers at the same time we are conserving the environment,” he said.

Six Bachelor of Science Degree graduates in fisheries technology at University of Dar es salaam started Samaki Farms in July 2021. They are aged between 23 and 25.

Mr Shoko said their firm is working at the university. They are changing organic waste into more protein feed ingredients for fish growth using black soldier fly larvae. The organic wastes are collected from homes, markets, and garbage dumps.

“Doing so the company helps to control the accumulation of wastes in the environment but also ensures cheaply available protein ingredients for fish feeds for the fish farmers,” he said.

(Reporting with Xinhua)

About Kaburu Mugambi

Kaburu Mugambi is a veteran of business reporting having worked with two national newspapers in Kenya. He is a graduate of economics from Kenyatta University. He started his journalism career in 2000 with The People Daily as a business reporter before becoming a business sub-editor. He joined Daily Nation in 2004 as a business writer. He holds a post-graduate diploma in mass communication from University of Nairobi's School of Journalism and an MBA in marketing from the same university. In 2016, he founded Water Tower, a media firm focused on water, energy and climate. Its content cuts across water, energy and climate with emphasis on adaptation and sustainability.

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