The Effect of Antibiotics on Bacteriome of Sitophilus oryzae and Rhyzopertha dominica as a Factor Determining the Success of Foraging: A Chance for Antibiotic Therapy in Grain Stores

Abstract

Rice weevil (Sitophilus oryzae) and the lesser grain borer (Rhyzopertha dominica) are very important warehouse pests and, therefore, their control is crucial. At a key moment in the life of adult Sitophilus spp., the obligatory symbiotic nature of the Sodalis pierantonius bacterium opens up a new perspective for natural antibiotics and bactericides. In this study, we used nanopore sequencing for 16S rRNA barcoding to evaluate the internal bacteriome of S. oryzae and R. dominica and sterilized the insects’ internal microbiome with gentamicin. The treatment of the interior of S. oryzae with gentamicin (30 mg·g−1) hampered insect functioning (supposed lack of DOPA (4-dihydroxyphenylalanine) synthesis, stabilizing the exoskeleton by Sodalis pierantonius symbiont) and elicited a lethal effect in the first stages of this pest’s adult life. In addition, we identified biochemical biomarkers (enzymatic activity and substrate utilization) active in living individuals, but inactive in dead individuals (e.g., C8 esterase/lipase and α-chymotrypsin).