Life history parameters of the rove beetle, Atheta coriaria and suitability as a biological control agent against the fungus gnat, Bradysia sp. nr. coprophila

Fungus gnats (Bradysia spp.) are a major insect pest of greenhouse production systems in the USA. A number of biological control agents have been successfully used in dealing with fungus gnats, including the rove beetle Atheta coriaria, which is a predator that may regulate fungus gnat populations. Despite the evidence associated with its potential as a biological control agent there is no quantitative information available on the efficacy of A. coriaria against the fungus gnat Bradysia sp. nr. coprophila. The overall objective of this study was to evaluate A. coriaria as a biological control agent against the fungus gnat under laboratory conditions. Life history parameters were determined based on visual observations. The total development time from egg to adult was 15.8 ± 0.39 days at 26°C. After one generation, 69.1 adults were produced per female. The lowest number of adults per female was 39 while the highest number was 104. Adult longevity was 40.1 days and the sex ratio was 1:1. High adult survival was associated with a growing medium moisture content >60%. Efficacy was evaluated in petri dishes and deli squat containers using growing medium as a substrate and different predator and prey densities. Although there were no significant differences in prey consumption among the different predator:prey, there was a positive numerical response as higher consumption rates per adult were observed at higher prey densities. Consumption rate was higher associated with second instar than third instar fungus gnat larvae which suggest that early releases may positively influence predation.