SUSCEPTIBILITY OF ADULT COLORADO POTATO BEETLE (LEPTINOTARSA DECEMLINEATA) TO THE FUNGAL

Factors influencing the susceptibility of adult Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), to the fungal entomopathogen, Beauveria bassiana (Bals.), were studied. In an assay comparing trials between a): laboratory reared, non-diapausing beetles and b): field collected, post-diapausing beetles, survival of B. bassiana treated beetles was higher for non-diapausing adults, however, control mortality was higher for post-diapausing adults. In a similar assay with field collected pre- and post-diapausing beetles, survival of B. bassiana treated individuals was higher for post-diapause adults and control mortality was higher for post-diapausing adults than pre-diapausing beetles. In a third experiment, the effect of time from eclosion from the pupal case on susceptibility of laboratory-reared, non-diapausing adults was evaluated. A trend of increasing susceptibility up to 60 degree days (base 10 " C) was be seen, and a significant decline of mortality occurred after 125 degree days. The effect of sublethal and lethal doses of B. bassiana were evaluated on the survival of overwintering beetles. B. bassiana dose had no effect on the proportions of beetles sporulating or dylng