Heterorhabditis brevicaudis: A New Nematode Species Isolated from El-Dakhla Oasis in Egypt and Its Efficiency against Some Lepidopteran Pests

Abstract

Background: Entomopathogenic nematodes have been used as biopesticides for controlling insect pests in niche markets. Many new isolates have been recovered from soil of natural habitats in many parts of the world. Native EPNs may be more suitable for controlling local pests. Therefore, isolation and identification of native nematode-bacterial associations are necessary for the successful control of endemic pests. Methods: The occurrence of an EPN, Heterorhabditis brevicaudis and its symbiotic bacteria was newly isolated from Egypt and recorded for the first time in this report. Diagnosis was based on morphometric characteristics and cross-hyperdization. Biochemical characterization and antibiotic activity of its bacteria were investigated. The new species activity was studied against four lepidopteran pests under laboratory conditions. Results: The isolate was proved to be a new species and was congruently belongs to H. brevicadus. The bacteria produced very strong bioluminescence and its antimicrobial activity is of medium level. H. brevicaudis was highly pathogenic to G. mellonella; T. absoluta and A. ipsilon larvae when mature larvae were treated with doses of 150, 100, and 50 IJs/ml, respectively. Conclusion: This is the first report of H. brevicaudis from Egypt. Data showed that the isolate is a new heterorhabtid species. Its symbiotic bacteria belong to ideal criteria and parameters that support nematode growth and pathogenicity. The antibiotics production is an advantage for the successful culturing of EPNs. This new EPN had a good impact against the four tested economic insect pests and could be positively enrolled in an integrated pest management program.