The RPW infestation elicit a control-factor repressive environment

Insects and Bacteria can engage symbiotic interactions that profoundly affect the fitness of the actors. Focusing on the facultative symbiosis among the Weevil and the Red Pigment Producing Bacteria (RPPB) Serratia marcescens (Enterobacteriaceae), its strictly related S. nematodiphila, Candida tropicalis (Berkhout, 1923, Fungi Saccharomycetaceae) and Hyphopichia burtonii (Boidin, Pignal, Lehodey, Vey & Abadie) Arx & Van der Walt (Fungi Incertae sedis) we suggest that this association has certainly driven their reciprocal adaptation. Our studies demonstrate the regular association of RPPB and yeasts with the plant - on egg chamber and pupal case walls - and the insect cuticle during oviposition, larval and pupal steps. By dissecting we also demonstrated the occurrence of microorganisms either in larval or adult RPW gut or into the female reproductive apparatus lumina. Dissecting the reproductive apparatus of ready-to-ecdysis female pupae revealed them to be devoid of microorganisms. The latter are re-acquired while teneral adult females rest 3-5 days in their pupal cases. A first metabolomics study by GC HFTOF MS to the compounds resulting from anaerobic one-larva breeding revealed high EtOH levels, and several other classes of compounds probably resulting from microorganism’s metabolism. Moreover, in plate experiments show a clear antimicrobial activity of RPPB against Gram positive (Bacillus megaterium, B. pumilus, Staphilococcus aureus, Lysinibacillus spp., Paenibacillus spp.) and Gram negative (Salmonella typhimurium, Klebsiella pneumoniae, Escherichia coli) bacteria possibly due to prodigiosin. The presence of the same weevil-borne RPPB & yeast in infested palm tissues and the heat increment induced by facultative fermenting ability of Serratia, as demonstrated by API20E system tests, close the circle of this presentation. We suggest that RPW infestation induce an environment that repress RPW biological control-factors because is intensely bacterized, hot, antibiotic, fermenting and rich in EtOH and organic acids.