Development of new methods to stimulate the production of antimicrobial peptides in the larvae of the black soldier fly Hermetia illucens

Abstract

Abstract The world population is projected to reach a staggering 9.8 billion people by the year 2050, placing pressure on our already precarious food security. The need to raise more livestock is unavoidable. The black soldier fly (Hermetia illucens) feeds on a variety of organic wastes. Therefore, H. illucens larvae have already been used as a partial substitute for fishmeal. In contrast, the use of antibiotics in livestock feed as a growth promoter and prophylaxis is endangering global health due to the threat of antimicrobial resistance. Therefore, efforts are underway to find natural substances that can act as substitutes for antibiotics with similar weight gain effects. Insect antimicrobial peptides are defense molecules with distinct structural traits that enable permeation and disruption of target membranes. Here, we investigated various methods for stimulating synthesis of AMPs in H. illucens larvae. The activation of innate immune response pathways leading to the production of various types of AMPs upon thermal injury was also investigated. Although not using bacteria, the thermal treatment to elicit expression of AMP genes was similar to the infection by Gram-positive bacteria. Our findings might prove beneficial in the industrial use of black soldier flies to maintain livestock and improve environmental health.