Bioactivity of fungi isolated from coconut growing areas against Rhynchophorus palmarum

Abstract

The objective of this work was to evaluate the chitinolytic activity and bioactivity of fungi isolated from the palm weevil (Rhynchophorus palmarum) and from soil samples from coconut (Cocos nucifera) crops against the insect itself. Initially, to determine the chitinolytic properties of the isolated fungi, their ability to hydrolyze chitin in a liquid culture medium was evaluated. Then, preliminary pathogenicity assays were carried out, using the bean weevil (Acanthoscelides obtectus) as a reference, to select the fungal isolates to be used in the experiments with the palm weevil. Finally, the bioactivity of two selected entomopathogenic fungi on palm weevil larvae and adults was assessed. There was no direct correlation between chitinolytic activity and pathogenicity capacity on the bean weevil nor between the isolates and bioactivity on the palm weevil. Beauveria bassiana CSU9 shows the highest activity on palm weevil larvae and adults, with a median lethal time of 0.8 and 14.4 days, respectively.