Bacillus thuringiensis treatment alters larval growth, hemocytes and modulationof Hsp70 in Rhynchophorus ferrugineus

Abstract: To study the pathogen-host relationship, we used the model of the entomopathogenicbacterium Bacillus thuringiensis (Bt) and Rhynchophorus ferrugineus, a quarantine pest that attackspalm trees. In particular, we focused on the Bt stress-induced infections. We studied the effect of Bton larval growth, on hemocytes and on the expression of the heat shock proteins. HSPs are rapidlysynthesized in the cell after exposure to stress including pathogens. Hsp70 was evaluated in thesupernatant of the hemocyte lysate (HLS) obtained from larvae fed with Bt. This is the first timethat the presence of Hsp70 has been recorded in R. ferrugineus. Bt has negative effects on larvalgrowth, on total hemocytes counts and on the hemocyte type. In addition Hsp70 expression wasmodulated in time (3h, 6h, 12h, 24h) in response to Bt ingestion, highlighting that Bt is a stressfactor for the R. ferrugineus. Further investigation is needed to understand the possible correlationbetween the reduction of hemocytes and Hsp70 modulation.