Mortality Induced by Bacillus popilliae in Cyclocephala parallela (Coleoptera: Scarabaeidae) Held under Simulated Field Temperatures

Abstract

The bacterium, Bacillus popilliae Dutky, causes milky disease in numerous species of scarabs around the world. Bacillus popilliae induced mortality in naturally infected grubs (third instars) of Cyclocephala parallela Casey was measured when held under simulated field temperatures. Our data show that visual examination in the field underestimates the percentage of grubs actually infected by B. popilliae. 5.6 to 8.2 times as many milky disease infected grubs died during the first 60 days of incubation under simulated field temperatures than did uninfected grubs. These data show that the widely used prevalence value underestimates the total mortality which this bacterium ultimately causes to C. parallela.