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Black soldier flies' larvae can cut stench of raw waste: Japan study

A jar of powdered black soldier fly larvae is seen at the National Agriculture and Food Research Organization in Tsukuba, Ibaraki Prefecture, on April 24, 2023. (Mainichi/Mayumi Nobuta)

TSUKUBA, Ibaraki -- Black soldier flies, which have been gaining attention in Japan and elsewhere for their consumption of organic waste and usefulness as a source of animal feed, may also provide the key in eliminating the putrid odor of raw garbage, Japanese researchers have found.

    The team, including members of the National Agriculture and Food Research Organization (NARO) in the Ibaraki Prefecture city of Tsukuba, announced that they have developed technology to control the smell of raw garbage using the flies' larvae. The Mainichi Shimbun looked into this "reverse phenomenon" where flies are unexpectedly benefitting humans.

    Black soldier flies are native to North America and also breed outdoors in Japan, where they consume raw garbage and other items. In Japan and overseas, research is underway to use the flies' powdered larvae as fish and animal feed.

    The Japanese researchers including those at NARO are similarly working on the artificial breeding of black soldier flies and their conversion into feed. During their research, they noticed that the bad smell of raw garbage used to feed the larvae lessened as they were raised. To track the changes, the researchers prepared vials of food waste, split into those with and without black soldier fly larvae, and measured the levels of methyl gases responsible for foul odors. They found pockets of gas created by the decomposing food in the no-larvae vials but none in the vials containing the larvae.

    When they added larval feces to the food waste before it had decomposed, they found the level of gas decreased to as little as one-seventh of the original level. The team believes that the larvae's intestinal bacteria are effective in reducing the putrid odors. It is not known whether other fly species have the same odor-eating abilities.

    Assistant research group leader Tetsuya Kobayashi, a member of NARO, commented, "Black soldier flies like smelly places like household compost. We thought they merely consumed organic waste, so it was surprising that they were also reducing odors on the side." He said that if researchers can identify the bacteria, it could lead to the development of deodorants, and expressed eagerness to expand the production of black soldier flies.

    (Japanese original by Mayumi Nobuta, Tsukuba Local Bureau)

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