Students raise strange flies to make them 'eat' garbage

Hoa 'flies', Hoa 'black soldiers' are nicknames associated with Nguyen Trong Hoa for a long time but Hoa did not mind, on the contrary, she felt very proud.

The reason for this nickname is because he and his group have studied and used the black soldier fly to treat organic waste , helping to minimize the amount of waste gathered in landfills. In addition, because of its high nutritional value, black soldier fly pupae are also used to make food for cattle and poultry as well as used as organic fertilizer to improve poor soil and increase soil porosity. Do not affect the environment.

Hoa's research team consists of 4 members who are students of the Department of Food and Environmental Engineering, Nguyen Tat Thanh University, with the guidance of MSc. Le Nguyen.

Hoa said the black soldier fly originated in North America and could consume decaying organic materials, including carrion (dead bodies, dirty materials). Black soldier fly larvae decompose organic matter very quickly; Their growth depends on the quality and quantity of feed added.

Pineapple meal used to feed black soldier fly larvae.

The team conducted a pilot farming in My Tho area, Tien Giang province, with a bean residue collected from tofu kilns and pineapple skins collected from a candy factory. All are put into a puree and make food directly to the larvae.

In addition to abundant food sources, in order to have a healthy larvae to increase the efficiency of waste treatment, according to Hoa, they need to be raised under temperatures ranging from 25 - 35 degrees C, air humidity 60 - 80%, moisture content of 70 - 90% with a normal density of 2 - 3g eggs / m2 as well as substrate thickness ranges from 2-4 cm, this is the best condition for larval growth and development.

The team also created a bio-bin to help separate and disintegrate organic waste at home by punching holes below to collect leachate, and also having a larval trough on top. The use of household bio-waste bins not only creates a source of food for livestock, but also helps to sort waste at source, minimizing the amount of waste collected. Research results show that black soldier fly larvae grow quickly on two systems of tofu and pineapple pulp substrate.

Also according to Trong Hoa, the substrate should be provided in separate batches to help the larvae thoroughly treat the waste before they produce a bad odor; Avoid providing one substrate at a time during culture. Because then the ability to decompose the larvae is not enough, creating favorable conditions for bacteria, nem mushrooms grow to cause odors, increasing thickness and temperature in the substrate.

Light source must not be directed into the farming area. With cages, make sure the floor is smooth, no holes, recommended concrete or silver lining, do not feed directly on the ground. In the rainy season, it is necessary to be careful for rearing the larvae, because the larvae are adapted to temperatures from 27 degrees C - 33 degrees C.

In the natural world, black soldier fly larvae are known as voracious, having a wide mouth structure that eats all organic compounds quickly when compounds have time to decompose and produce odors. , thus helping to eliminate odors. The team conducted experiments and the results showed that, by ingestion and digestion method, the larvae can reduce from 80 - 90% of the waste and any pathogens.

"Black soldier flies can consume food 4 times the body weight of the day. In an area of ​​1m2 (2-3 g larvae), black soldier fly larvae can consume 30 kg of household waste / day, and in the trash is 15kg of food waste per day, " Hoa said.

Vietnam is located in the tropical monsoon hot dry season, which is a favorable condition for the development of black soldier flies. In particular, the black soldier fly has been recognized by the United Nations Agricultural and Trade Organization (FAO) as an insect breed that is prioritized for waste treatment and uses protein content instead of depleted fish resources.

The black soldier fly has a scientific name of Hermetia Illucens. The adult black soldier fly is black, 12-20mm long, has a life cycle of about 40 days, starting from eggs, larvae, pupae and finally molting into black soldier flies. Adult flies live for about a week and then die. Adult female flies lay 500 to 800 eggs. Currently, one kilogram of egg fly is sold for 15-20 million. One kilogram of fly eggs can hatch and grow into 3 to 4 tons of nymphs.