A report on Purpureocillium lilacinum found naturally infecting the predatory mite, Balaustium murorum (Parasitengona: Erythraeidae)

ABSTRACTAdult mites Balaustium murorum collected from a wild population died in laboratory storage containers and became mouldy. The fungus was identified as Purpureocillium lilacinum (predominate isolate) by 98% internal transcribed spacer (ITS) and beta-tubulin (Bt2a/Bt2b) BLAST match to authentic strains from soil. Larvae, deutonymphs, and adults could be artificially infected by topical application with a 107/ml spore inoculum, resulting in rapid dehydration and an increased mortality. This strain of P. lilacinum was more virulent to larvae than post-larval stages. Post-treatment, P. lilacinum was re-isolated internally with high frequency from cadavers. This P. lilacinum has a 25°C optimal growth temperature, 20–35°C thermal growth range, 0.997 aw optimal water activity (aw), and a minimum 0.96 aw to produce spores. Results indicate that infection with P. lilacinum can occur for population control, most likely during periods of moderate temperature and frequent rainfall. Because P. lilacinum is comme...