Field evaluation of the entomogenous fungus Metarhizium anisopliae (DAT F-001) as a biocontrol agent for the redheaded pasture cockchafer, Adoryphorus couloni (Coleoptera: Scarabaeidae)

Abstract

The field efficacy of Metarhizium anisopliae DAT F-001 for L3 larvae of Adoryphorus couloni was examined on two sheep grazing properties in central Tasmania ('Glenmorey' and 'Warringa'). Experiments included application timing and dose rate studies. All experiments significantly (P < 0.05) reduced survival of L3 larvae. At 'Warringa' DAT F-001 reduced the survival of L3 larvae by 81.5% in late spring following incorporation of 6.3x104 sp/g soil into pasture soils the previous autumn. The experiments showed that autumn application was unlikely to sufficiently reduce the L3 larval population quickly enough to avoid pasture damage in the first year. However, the following year, the overlapping larval populations in the treated plots at 'Warringa7 were reduced by 80% and the subsequent generation of L3 larvae at 'Glenmorey' 2 years after application was reduced by 47%. Additionally, the level of DAT F-001 in the soil remained at or near the original application levels over the experimental periods (12-30 months). We conclude that there are limited opportunities to use DAT F-001 to control an initial pest population, but the fungus has the potential to provide longer-term suppression of subsequent pest generations.