Pathogenicity of Two Fungal Strains, Metarhizium Brunneum (ORP-18) and Beauveria Bassiana (GOPT-331), Against Larvae of the European Tent Caterpillar Malacosoma Neustria (L., 1758) (Lepidoptera: Lasiocampidae)

Abstract

Malacosoma neustria is a pest for many plant species. Instead of chemical control, eco-friendly biological control methods should be used to combat this species. The purpose of this study was to evaluate the efficacy of isolates of two entomopathogenic fungi, Metarhizium brunneum (ORP-18) and Beauveria bassiana (GOPT-331), used as both oral and spray application on the 4th instar larvae of M. neustria under laboratory conditions. In addition, it was determined how the infection affected the amounts of malondi-aldehyde, NADPH oxidase and glutathione of the larvae. Both fungal isolates were placed in separate containers at 2 ml for each concentration (1x10(5) , 1x10(6) , 1x10(7) and 1x10(8) conidia/ml) in the oral group and contaminated all over the Elaeagnus rhamnoides leaves and then the contaminated leaves were offered to ten larvae in each container. For the spray group, 2 ml of spray was applied to every ten larvae placed in the containers for each concentration. As a result, it was found that both isolates killed the larvae. The ORP-18 isolate caused higher mortality rates than the GOPT-331 isolate. The spray application was more lethal than the oral application. With increasing conidial concentrations of both isolates, the amounts of malondialdehyde and NADPH oxidases increased, while the glutathione amounts decreased, which indicated the adverse effects of reactive oxygen species (ROS) on larval survival. On the basis of the results, it is recommended to use the ORP-18 isolate for the control of larvae of M. neustria.