INCIDENCE OF BACILLUS POPILLIAE IN DIFFERENT LIFE STAGES OF FLORIDA SUGARCANE GRUBS (COLEOPTERA: SCARABAEIDAE)

Abstract

All life stages of Cyclocephala parallela Casey and Ligyrus subtropicus Blatchley were collected from commercial sugarcane fields in southern Florida from May, 1985 to May, 1988. These specimens were examined using phase contrast microscopy for the presence of the milky disease bacteria, Bacillus popilliae Dutky. In addition, field soil temperatures were measured, and the survival of milky grubs under simulated field temperatures was determined in a laboratoiy. Bacillus popilliae was not detected in the eggs or pupae of either grub species. The bacterium was found in 0.2% and 0.3% of adults in C. parallela and L. subtropicus respectively. The highest incidence of B. popilliae in both species was observed in the larval stage being 6.1% and 1.9% in C. parallela and L. subtropicus respectively. Survival data showed that B. popilliae was not limited in its development in infected third instar grubs by soil temperatures at any time during the year in Florida sugarcane fields.