PATHOGENICITY ENHANCEMENT OF METARHIZIUM-ANISOPLIAE AND BEAUVERIA-BASSIANA TO FIRST INSTARS OF DIAPREPES-ABBREVIATUS (COLEOPTERA, CURCULIONIDAE) WITH SUBLETHAL DOSES OF IMIDACLOPRID

Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Met schnikoff) Sorokin combined with sublethal doses of imidacloprid as a contact or oral treatment increased synergistically mortality and myco sis of 1st instars of Diaprepes abbreviatus (L.). Time to death was al so reduced significantly through the synergistic effect of the fungal/ chemical treatment. Synergism only occurred at concentrations of imida cloprid of 100 ppm or greater. At fungal concentrations of 10(6) and 1 0(7) conidia per milliliters and imidacloprid at doses of 100 ppm or g reater, larval mortality and mycosis reached 90-100%. Mycosis was redu ced with imidacloprid at 1,000 ppm. There were no differences in larva l mortality or mycosis by M. anisopliae when imidacloprid was administ ered by contact or per os. The active ingredient rather than the inert carrier was the main component responsible for the synergism between imidacloprid and entomopathogenic fungi.