PATHOGENICITY OF BEAUVERIA-BASSIANA (BALSAMO) VUILLEMIN TOWARD LYGUS BUG (HEM, MIRIDAE)

We present the first report of the susceptibility of the three predomi nant Lygus species in western Canada to B. bassiana. Three species of adult lygus bug were collected in Saskatchewan, Canada and subjected t o a bioassay against the entomopathogenic fungus, Beauveria bassiana. The lygus bugs were allowed to walk on a sporulating culture of B. bas siana. The LT50 was 4.97 days and 90 % mortality was achieved in 7 day s. Within 3 days, sporulation was observed on the surface of all infec ted insects. Microscopic examination of the thin sections of infected lygus bug cadavers revealed massive disintegration of internal muscle tissues while breaching of the cuticle was generally localized to the intersegmental membranes.