Occurrence, Characterization and Pathogenicity Test of the Fungi, Aspergillus flavus and Fusarium oxysporum Isolated from Cadavers of Scolytus amygdale Guerin-Meneville (Coleoptera: Curculionidae: Scolytinae)

Abstract

Natural mortality of the almond bark beetle, Scolytus amygdali Guerin-Meneville (Coleoptera: Curculionidae: Scolytinae) was studied during its spring generation under the bark of infested almond tree branches in Tunisia. Dead larvae and adults of the beetle were collected from the field and analyzed under the laboratory conditions. Two main fungal isolates were obtained from the cadavers of S. amygdali individuals,identified using morphological and molecular tools, as Aspergillus flavus and Fusarium oxysporum. In preliminary studies conducted under laboratory conditions, species of Aspergillus and Fusarium fungi were reported virulent at the concentrations of (0.4 x 10(7) conidia/ml) to S. amygdali. In order to test the pathogencity of the two isolated fungal species, similar concentrations were applied on larvae and adults of healthy S. amygdale individuals. Both fungi were found significantly virulent immediately after 24h under laboratory conditions. Further investigations for their suitability as biocontrol agents in the field are required.