Analysis of the antibacterial activity of Hermetia Illucens oil towards mastidogenic agents in cattle

Among the most prevalent diseases worldwide that affect the dairy sector is “Bovine Mastitis”; this disease drastically reduces the productive performance and affects the health of dairy cows, causing great economic losses. The main strategy for prevention and treatment of intramammary infection in dairy cows is still the administration of antibiotics, but their efficacy has been compromised by increasing bacterial resistance. Therefore, it is urgent to find new alternative strategies to reduce the use of antibiotics. The aim of this study was to evaluate, in vitro, the antibacterial activity of Hermetia illucens (HI) oil against pathogens responsible for bovine mastitis, including the following bacterial strains: Staphylococcus aureus (field strain), Streptococcus uberis (TUCC N° 555), Streptococcus agalactiae (TUCC N° 557), Streptococcus dysgalactiae (TUCC N° 558), and Streptococcus bovis (IZS N° 95670). For this purpose, three different concentrations of HI oil were tested, at 20%, 40% and 50%. All these experimental conditions were exposed to the surface spreading method and the bacterial concentration was quantified at three-time intervals by reading the CFU/mL on the corresponding plates after 24 hours of incubation. The results obtained demonstrate the potential bacteriostatic effect of HI oil on four of the five bacterial strains considered in this study. After 24 hours of inoculation, HI oil at a concentration of 50% significantly (P < 0.05) inhibited the growth of S. aureus, S. agalactiae, S. uberis and S. dysgalactiae. As far as S. bovis is concerned, no significant differences (P > 0.05) were obtained at any time interval. Further studies will be needed to validate the obtained results, as well as to enhance the inhibitory effect of HI oil. In any case, these data will serve as a basis for future research and applications in animal health, for both in vitro studies and in vivo applications. Keywords: antibacterial, Hermetia illucens, mastidogenic bacteria