Association of entomopathogenic fungi with exotic red palm weevil in treated and untreated Phoenix canariensis

Abstract

Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is introduced pests of established Phoenix canariensis in Sicily (Italy). A three-year field survey of R. ferrugineus generated data on species of fungal associated with larval, pupae, and adult R. ferrugineus recovered from several cadavers. Moreover specimens were collected from infested Phoenix canariensis in scattered locales in Sicily to determine also infection rates with entomopathogenic fungi over 3 years. Collection was done after overwintering period, during summer and at the beginning of autumn in palm, untreated and treated with chemical pesticides. As can be expected the highest infestation was recorded after overwintering period in untreated palms. The infection rates of larvae, pupae, males, and females were 5.0%, 35.0%, 3.5% and 4.3% respectively. Samples mainly from field-collected pupae, were utilized to inoculate Nutrien agar plate. Isolated fungal colonies were characterized both by scanning (S.E.M.) and confocal laser scanning (C.L.S.M.) microscopy and molecular analysis (specific molecular markers). Entomopathogenic fungi were identified as Beauveria bassiana, Pichia sp., Trichosporon multisporum and Trichosporum sp., Verticillium lecanii and Verticillium sp. (a member of the Verticillium lecanii species complex).