Laboratory Evaluation of the Insecticidal Toxins from Entomopathogenic Nematode Symbiotic Bacteria to Control Vegetable Diseases and Pests

Abstract

Aims: Entomopathogenic nematode (EPN) and its symbiotic bacterium are used worldwide as microbial control agents. Toxins from EPN symbiotic bacteria were isolated and provided basis for using this potential resource as biocontrol agent against vegetable diseases and pests.
 Study Design: The toxins were extracted from 28 strains of bacteria associated with entomopathogenic nematodes. The insecticidal activity and antibiotic activity against vegetable diseases and pests were determined through bioassay.
 Place and Duration of Study: College of Bioscience and Biotechnology, between May 2020 and September 2021.
 Methodology: The toxins were extracted by (NH4)2SO4 precipitation method. The insecticidal activities and antibiotic activities were evaluated using bioassay in the laboratory.
 Results: The toxins of the symbiotic bacteria associated with EPN had certain insecticidal activities on the first instar larvae of Plutella xylostella and Laphygma exigua, and strain SY5 showed the most obvious antifungal activities against Trichothecium roseum and Fusarium oxysporum.
 Conclusions: The toxins of the EPN symbiotic bacteria SY5 had good insecticidal activity and antibiotic activity. Therefore, it has the potential for use against vegetable diseases and pests as biocontrol agents.