Screening and Pathogenic Potential of Entomopathogenic Fungi Against Dactylopius opuntiae (Cockerell. 1929)...

The cactus pear sector in Morocco remains seriously threatened by the cactus cochineal, Dactylopius opuntiae, the primary pest of Opuntia species worldwide. The objective of this study was to evaluate the entomopathogenic potential of fungi isolated from field-collected mycosed cochineal cadavers. Eleven fungal isolates were tested in the laboratory on adult female insects, leading to the selection of five isolates with particularly high efficacy: Fusarium equiseti (PV404064), Fusarium equiseti (PV404085), Aspergillus niger (PV706915), Aspergillus flavus (PV897714), and Alternaria destruens (PV403730). Estimation of LD50 values indicated that the five isolates exhibited similar levels of virulence. Tests conducted on infested cladodes confirmed the laboratory findings: 15 days after application, infestation rates were significantly reduced compared to the control. The study of mechanisms of action revealed diverse enzymatic activities: all tested fungi exhibited marked lipolytic, proteolytic, and phospholipase activities, whereas chitinolytic activity was detected only in the two F. equiseti isolates. Metabolic flexibility was also assessed: all isolates demonstrated 100% growth in minimal media supplemented with xylose and glucose compared to PDA medium. Finally, analysis of the secondary metabolism revealed the presence of several genes associated with the entomopathogenicity of the fungi against their hosts in the genomes of the five tested fungal isolates.