In vitro liquid culture production and post-production pathogenicity of the hybrid Heterorhabditis bacteriophora HBH strain

Abstract

Entomopathogenic nematodes (EPNs) are biological control agents that can be used as alternatives to chemical pesticides against insect pests. Liquid culture is the most suitable method for large-scale production of EPNs. However, to achieve commercial success, the optimization of production parameters is crucial. This study aimed to identify the optimal temperature, pH and dissolved carbon dioxide concentration for the liquid culture production of Heterorhabditis bacteriophora hybrid HBH strain. Temperature and pH experiments were conducted in Erlenmeyer flasks, while carbon dioxide experiments were conducted using a 5 L bench-top fermenter. The results revealed that the best yield was achieved at a temperature of 26 degrees C, a pH of 9, and a dissolved carbon dioxide concentration of 8-9%. The highest yield was observed between the 14th to 16th days in almost all batches. Although no significant difference was found in the pathogenicity of the populations, certain populations obtained from carbon dioxide trials exhibited greater efficacy at lower doses than in vivo populations. The liquid production of the HBH hybrid strain is a critical step towards commercial production. Further goals include the optimization of additional parameters for large-scale production. The findings of this study are expected to have practical implications for the industrialization of native hybrid EPN strains.