Evaluation of the entomopathogenic fungus Beauveria bassiana strain ATCC 74040 for the management of Ceratitis capitata

The effectiveness of the bioinsecticide Naturalis based on the Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina Hyphomycetes) strain ATCC 74040 against the medfly Ceratitis capitata (Wiedemann) (Diptera Tephritidae) was evaluated in laboratory and field experiments. Under laboratory conditions, the bioinsecticide (150 ml/l) protected fruits from medfly ovipositions more effectively when they were covered uniformly with a spray volume of 5.4 ml/fruit. In laboratory choice bioassays medfly females laid respectively 5 and 3 times more eggs on untreated fruits and on fruits sprayed with inert co-formulants of the bioinsecticide than on fruits treated with the bioinsecticide. However, females did not prefer to oviposit on untreated fruits over fruits sprayed with co-formulants, suggesting that inert co-formulants did not affect oviposition behaviour of C. capitata females. Adults landed indifferently on both untreated fruits and fruits sprayed with the bioinsecticide and medflies did not appear to be repelled by chemical compounds or fungal structures of B. bassiana. However, in no-choice laboratory tests significantly more punctures per fruit were observed on untreated fruits than on fruits treated with the bioinsecticide, suggesting that medfly females prefer untreated over treated fruits to effectively oviposit. Preliminary field trials were conducted to confirm the effectiveness of the B. bassiana-based bioinsecticide for medfly control. The bioinsecticide was as effective as a pyrethroid in reducing adult medfly populations and protecting orange fruits in the field. However, our results suggest that the bioinsecticide could be a valuable additional tool for the management of C. capitata in both integrated and organic groves.