Investigation on endosymbionts of Mediterranean flour moth gut and studying their role in physiology and biology

The bacterial flora of flour moth and their role in the physiology of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) were investigated. The gut flora of E. kuehniella was isolated on Luria Bertani Agar (LBA), followed by incubation at 28 °C respectively for 48-72 h. The isolates were identified using 16S rRNA sequencing. Altogether five bacterial species of different genera were identified as Bacillus infantis, Streptomyces cacaoi, Janibacter sp., Stenotrophomonas sp. and Acinetobacter sp. The fourth instar larvae reared on artificial diet without any antibiotic showed higher efficiency of conversion of digested food (ECD) and efficiency of conversion of ingested food (ECI) (16.068 ± 0.568% and 14.455 ± 0.448%), respectively. Approximate digestibility (AD) and Consumption index (CI) of the fourth instars larvae were higher on artificial diets containing tetracycline. The higher activity of alpha-amylase and general proteases were observed in the midgut of larvae reared on artificial diet containing antibiotic chloramphenicol. Total protein and lipid value were higher respectively in larvae that were reared on artificial diet containing streptomycin sulfate and artificial diet containing tetracycline. It seems that antibiotics had no significant effect on enzymatic activities of E. kuehniella. The larvae performed well in tetracycline treatment as per larval developmental duration compared with other treatments. Therefore, the gut bacteria do not seem to play a crucial role in the survival and development of the E. kuehniella. However, the question of adaptation of this pest species to hosts rich in protease inhibitors, such as flour has to be examined and ascertained.