Bacillus thuringiensisis considered a potential useful entomopathogen of Rhynchophorus ferrugineus(RPW), a quarantine pest that attacks the palm trees. We compare the effects of Bt in mature larvae, females and males. The pathogenicity activity of Bt was evaluated estimating: Median Lethal Dose (LD50), Median Lethal Time (LT50), and Total Haemocytes Count (THC) and Differential Haemocytes count (DHC), and finally the expression of the stress protein Heat Shock Protein 70 in the haemocytes and in the brains. RPW mortality exhibited a positive trend with the dosage and duration of exposure to Bt. The larvae were more susceptible than adults and the LD50 of females was even the double value of the one of larvae. Similarly, the LT50 value was higher for females than males and larvae. Treatment with sub-lethal dose of Bt induces a decrement in THC in larvae, females, and males. In treated larvae plasmatocytes decrease while oenocytes and spherulocytes increase. In treated females all type of haemocytes decrease, while in males the number of plasmatocytes decreases and the granulocytes increase. We also registered the stress answer directly on hemocytes, showing that already at 3, hours after eating Bt, it modulates the expression of the stress protein Hsp 70. This effect was also observed in the brain tissue at 6 hours after treatment.The results confirm that the Bt treatment induces a pathogenic state in RPW larvae and adult of both genders, that answer only after few hours from ingestion, however, the effects are different in magnitude and in type of target. The highlights can be useful to understand better the relationship pathogen-host and to implement the integrated control of phytophagous.
|Titolo della pubblicazione ospite||Libro abstract XXVI CNIE|
|Numero di pagine||1|
|Stato di pubblicazione||Published - 2021|