38th Annual Meeting of the Society for Invertebrate Pathology

The oca weevil, Adioristidius tuberculatus Voss is the most important pest of the Andean oca tuber crops (Oxalis tuberosa Molina). Entomopathogenic fungi offer good possibilities as control agents in Integrated Pest Management (IPM) strategies. Fungi were isolated from weevils collected from fields and storages in Junín, Peru. These were identified and characterized morphologically and physiologically in the laboratory. Natural infection rates were 10% and 12% for the oca weevils in the both field and storage. Nine fungi strains were isolated and identified as Paecilomyces fumosoroseus, Beauveria bassiana and Beauveria brongniartii. Pathogenicity tests revealed high rates of infection (>90% in larvae-IV and >80% in adults) for the isolates CIP76 P. fumosoroseus, CIP78 B. brongniartii, CIP81 B. bassiana and CIP83 P. fumosoroseus in oca weevils. The isolate CIP76 P. fumosoroseus highest efficacy against the oca weevil (Larvae: LC₅₀ = 1x10⁷ conidias ml^-1, TL₅₀ = 7 days; adults: LC₅₀ = 1,3x10⁷ conidias ml^-1 and TL₅₀ = 29 days). The morphological characterization of the three species showed that the size of their conidia were outside of the range that is characteristic for each species. CIP76 P. fumosoroseus was the most virulent isolates with good multiplication of conidia, which make them very prospective for usage in Integrate Pest Management strategies of A. tuberculatus.