Dosage Response Mortality of Japanese Beetle, Masked Chafer, and June Beetle (Coleoptera: Scarabaeidae) Adults When Exposed to Experimental and Commercially Available Granules Containing Metarhizium brunneum.

Field-collected adults of three genera of turf-infesting scarabs, Japanese beetle ( Popillia japonica Newman), June beetles ( Phyllophaga spp.), and masked chafers ( Cyclocephala spp.), were exposed to experimental and commercial granule formulations of the entomopathogenic fungus Metarhizium brunneum (Petch) strain F52 to determine their relative susceptibility. Experimental granules contained microsclerotia produced by liquid fermentation with the ability to produce fresh conidia when rehydrated and commercial granules were Met 52 granular bioinsecticide. All three groups of scarab adults showed a positive dosage response to the fungus when exposed in cups of potting mix treated with the granules. LC 50 values for microsclerotia granules were 1.9 × 10 7 , 7.1 × 10 6 , and 3.2 × 10 6 conidia cup -1 for P. japonica , Phyllophaga spp., and Cyclocephala spp., respectively. LC 50 values for Met 52 granules were 5.9 × 10 7 , 5.1 × 10 7 , and 7.6 × 10 6 conidia cup -1 , respectively. The experimental granules containing microsclerotia show promise as a viable commercial control agent. They can be produced using lower cost fermentation methods and applied at lower dosages (97 g for 100 m 2 as opposed to 489 g per 100 m 2 for Met 52). If M. brunneum is applied to control the aforementioned white grubs, our data indicate the potential for the adult beetles to also be infected as they enter the soil to lay eggs. Published by Oxford University Press on behalf of Entomological Society of America 2016. This work is written by US Government employees and is in the public domain in the United States.