On some Rhynchophorus ferrugineus (Olivier, 1790) ectosymbiotic bacteria found in lumina of female genital organs

Observations revealed a guild of microorganisms regularly released by RPW females with eggs and on egg-chamber walls that demonstrated to be either yeast or bacteria. Latter fraction includes red-pigment-producing bacteria (RPPB) also. This study focuses on the presence of the same egg-associated RPPB in specific places of female internal genital organ lumina, namely in the unpaired duct, in bursa copulatrix and in ovipositor. Moreover RPPB were also detected in virgin females and on the internal pupal chambers wall. RPPB were also found in adult female and larva gut lumina. Analysis of the 16S rDNA, gyrB, rpoB, recA and groEL sequences assigned RPPB to the species Serratia marcescens Bizio, 1823. Vertical transmission from egg to egg of RPPB is clarified by many repeated and focused bacterial collection from eggs, larvae, pupae, pupal cases, teneral and reproductive females. The production of pigments is of particular biological interest. In fact, pigments are bacterial secondary metabolites with many antagonistic effects e.g. antimicrobial, anticancer and immunosuppressive. Secondary metabolites with antimicrobial activity have been detected in vertically transmitted extracellular symbiont that protects their insect hosts against pathogens or predators. The ecological potential protective role of the weevil- associate Serratia may be inferred from antimicrobial activity that it exhibits. It was assessed by the agar well diffusion method against a number of Gram-positive bacteria (Bacillus spp., Paenibacillus spp. and Lysinibacillus spp.) reported as insect-pathogens and potential candidates as bio-control agents and Gram-negative (Salmonella typhimurium, Klebsiella pneumonia, Escherichia coli).