Foliar Application of Entomopathogenic Nematodes against Cereal Leaf Beetle Oulema melanopus L. (Coleoptera: Chrysomelidae) on Wheat

Abstract

Cereal monocultures are very susceptible to many pests, especially to those living on leaves, which largely affects yield by decreasing its quality. The most dangerous of them is the cereal leaf beetle (Oulema melanopus L.). In cases of heavy infestation by its larvae, the surface of plants may be reduced by 50%, and sometimes even by 80%, with a main yield loss of 10–25%. The aim of the presented study was to assess the efficiency of a native isolate of Steinernema feltiae (Filipjev, 1934) and commercial preparation Larvanem (Heterorhabditis bacteriophora (Poinar, 1975)) in controlling the larvae of O. melanopus, and to reduce crops damage in the field. Nematodes were applied in a dosage of 2 million IJs/m2 as a suspension of 11 litres per square metre. A hand sprinkler with field lance and flat-stream nozzles was used for applications at the lowest working pressure of 3000 hPa. The effectiveness of both nematode species was moderate: 47.8% for S. feltiae isolate and 49.5% for H. bacteriophora. The biggest reduction in leaf damage was found in crops treated with the commercial preparation, where the index of leaf infection was 32%, being more than twofold smaller than that for the control.