Fly Larvae May Become a Natural Antibiotic Against Plant Diseases

Aside from insects, farm crops need to be protected from phytopathogens, or parasitic organisms. New research from the Moscow Institute of Physics and Technology explores a unique antibiotic sourced from fly larvae.

The paper published in the journal Microorganisms describes how biotechnologists discovered proteins within the fat of black soldier fly larvae. The compounds have antimicrobial properties that kill phytopathogens, even antibiotic-resistant bacteria.

Phytopathogens can be fungi, a bacterial disease, or a viral disease that can cause damage to entire plantations. For example, the Panama disease is widespread among tropical climates where banana plantations thrive and are caused by a fungal disease in the soil.

Farmers typically use antibiotics to fight harmful diseases that affect crops, but over the years, microbes have evolved by developing resistance. Moreover, antibiotics target both harmful and beneficial microbes to plants.

Extracting Fly Larvae Compounds

The authors wrote, "the rapid increase of plant diseases caused by bacterial phytopathogens calls for an urgent search for new antibacterials." They analyzed compounds from the larvae of Hermetia illucens as a possible source of a new antibiotic.

Black soldier flies are native to South America and can also be commonly found elsewhere. Insect factories mass produce their larvae as feeds for fish and livestock. The fly larvae are known for accumulating fat and protein and can be fed to animals directly or in the form of protein extract.

Larvae lipids are rich in 'lauric, myristic, palmitic, oleic, capric, linoleic, and other medium-chain fatty acids," wrote the authors. Lauric acid has antimicrobial properties that can fight viruses such as measles and HIV.

During the study, the team mechanically squeezed the larvae under a press to extract its fat. They then searched for active compounds by testing multiple organic solvents. The solvent that worked best was made of hydrochloric acid, water, and methanol.

The solvent allowed the biotechnologists to extract active fatty acids within the fat. Elena Marusich said that the team discovered how to mix the organic solvents to extract the chemical compounds needed to develop antibiotics for crop diseases.

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Antibiotic Compounds

The extract, AWME, had antimicrobial properties more effective than currently available antibiotics, she explained. AWME "could virtually replace antibiotics in agriculture for fighting phytopathogenic bacteria."

They tested the extracted compounds against five phytopathogenic bacteria strains such as Pectobacterium atrosepticum which affects potatoes. After growing bacteria in Petri dishes, they were exposed to AWME in filter paper. The harmful pathogens were killed by the compounds with fly larvae. Moreover, the extract can be refrigerated to retain its antimicrobial properties.

Sergey Leonov acknowledged the work of Gennady Ivanov, the man how pioneered black soldier fly cultivation in Russia. He said that commercial use of the compound extract for agricultural uses "will require additional experiments with other common plant pathogens, as well as research into the mechanisms underlying the extract's antibacterial activity." In conclusion, the authors wrote that larvae fat can be used to develop effective natural disinfectants and antibacterial agents for agriculture crop protection.

(Photo: Photograph by James Castner, University of Florida.)

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