Effects of the entomopathogenic fungus Beauveria brongniartii on the non-target predator Poecilus versicolor (Coleoptera: Carabidae)

Non-target effects of the entomopathogenic fungus Beauveria brongniartii (Ascomycota: Clavicipitaceae) on Poecilus versicolor (Coleoptera: Carabidae), a potential antagonist of the European cockchafer Melolontha melolontha, were studied with three different B. brongniartii formulations, Melocont-Pilzgerste, Melocont-WP, and Melocont-WG. All formulations induced significantly enhanced mortality rates among third instar larvae of the target pest M. melolontha, but no negative effects on the non-target organism were observed. However, small but statistically significant differences were observed for P. versicolor when the fungus was applied: larval development time from first instar to adult stage was decreased by 6.8% (4 days) and the biomass of teneral beetles increased by 8.4% (3.7 mg) compared to that of the control groups. Additionally, third instar larvae of P. versicolor were exposed to B. brongniartii-infected M. melolontha cadavers to either consume material from the mycosed carcasses or come in contact with them while searching for food. Again, no significant negative effects on P. versicolor could be observed. The results suggest that under field conditions B. brongniartii would be a negligible risk for P. versicolor.