PATHOGENICITY OF BEAUVERIA-BASSIANA (BALS) VUILL AND VERTICILLIUM-LECANII (ZIMM) TOWARD BLISTER BEETLE, LYTTA-NUTTALI SAY (COL, MELOIDAE)

In the Saskatchewan prairies Nuttall blister beetle Lytta nuttali Say is a sporadic pest of forages, canola, faba beans (Vicia faba) and a variety of other crops like lupin (Lupinus spp.) and vetch (Vicia sativa). In this study we examined the effectiveness of various B. bassiana strains isolated from Russian wheat aphid, Diuraphis noxia (Mordv.) (DN 8806 and DN 8804); the greenbug, Schizaphis graminum (Rond.) (SG 8601, SG 8702, SG 8701) and GK 2016, USSR 2553; DAOM 210569, DAOM 144746; DAOM 71453; ATCC 44860 and Verticillium lecanii ATCC 46578. B. bassiana strain SG 8702 proved to be the most effective. Different strains of B. bassiana used in this study were found more pathogenic to Nuttall blister beetle than V. lecanii. Bioassays conducted using conidiospores, blastospores or its extracellular fraction with SG 8702 showed effective mortality. The results revealed that possibly fungal toxins may be involved in the early mortality observed with some B. bassiana isolates.