A DISJUNCT CALIFORNIAN STRAIN OF ENTOMOPHAGA-AULICAE INFECTING ORGYIA-VETUSTA

Fungal epizootics occurred in abundant Orgyia vetusta (western tussock moth; Lepidoptera: Lymantriidae) populations on Lupinus arboreus hush es growing on the Pacific coast north of San Francisco, California. Th e causative pathogen was isolated and identified as Entomophaga aulica e, Group II, based on RFLPs using rDNA and PCR-amplified rDNA products . Inability of this fungus to infect the lymantriid Lymantria dispar ( gypsy moth) confirmed its distinction from Entomophaga maimaiga, the o nly other member of this species complex which predominantly infects l ymantriids. Later instar wandering by O. vetusta in outbreak populatio ns and close proximity of larvae in dense populations are characterist ics most probably promoting development of E. aulicae epizootics; thes e life history patterns are also typical of lymantria dispar populatio ns experiencing epizootics of E. maimaiga. (C) 1996 Academic Press, In c.