Bacillus thuringiensis treatment modulate the HSP70 expression in larva and adult brain of Rhunchophorus ferrugineus

To study the pathogen-host relationship, we used the model of the entomopathogenic bacterium Bacillus thuringiensis (Bt) and Rhynchophorus ferrugineus, a quarantine pest that attacks palm trees. In particular, we focused on the Bt stress-induced infections. We studied the effect of Bt on larval and adult growth, and on the expression of the heat shock proteins (HSPs), rapidly synthesized in the cell after exposure to stress including pathogens. Bt has negative effects on larval and adult growth, on total hemocytes counts and on the hemocyte type. HSP70 was evaluated in the supernatant of the brain lysate obtained from larvae and adults fed with sublethal doses of Bt. HSP70 expression was modulated in time (3h, 6h, 12h, 24h) in response to Bt ingestion, highlighting that Bt is a stress factor for the R. ferrugineus. Further investigation is needed to understand the possible correlation between the reduction of hemocytes and HSP70 modulation. The potential costs of the different bioassay used will be compared.