Abstract
BackgroundEntomopathogenic nematodes (EPNs) are promising alternatives since they have many characteristics as a biological control agent against insect pests.ResultsAmong indigenous EPN isolated, adapted to local environmental conditions by employing the Galleria baiting strategy, only one sample was positive for the presence of EPNs. The new isolate was identified at the species level using DNA sequencing of the internal transcribed spacer region and the Basic Local Alignment Search Tool search of GenBank showed that the isolate had a high similarity (99%) with that sequence available for Heterorhabditis taysearae. The pathogenicity of the EPN isolate was tested against the cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), using different concentrations (60, 90, 120 and 150 IJs/larvae). Data showed that 150 IJs/larvae caused 100% mortality rate, followed by 120 IJs/larvae (90%), while 60 IJs/larvae showed the lowest rate (60%) after 72 h.ConclusionsThe present study indicated that the native isolate of EPN could be recommended against S. littoralis as an efficient tool in its control programs.
Highlights
Entomopathogenic nematodes (EPNs) are promising alternatives since they have many characteristics as a biological control agent against insect pests
Molecular identification and phylogenetic analysis The EPN isolated from the positive samples were further identified to the species level
The PCR amplified product revealed approximately 700 bp of the 5.8S rDNA, ITS1 and ITS2 sequence, and according to the Blast search, the new isolate was belonged to the genus Heterorhabditis and showed 99% similarity with Heterorhabditis taysearae based on the sequence similarity, submitted to GenBank with accession no. (MW543946.1)
Summary
Entomopathogenic nematodes (EPNs) are promising alternatives since they have many characteristics as a biological control agent against insect pests. In Egypt, the pest causes economic losses to cotton plants and to 90 different economic crops from 40 different plant families. The rife use of the pesticides to control pests leads to the development of insect resistance, pollution, and biodiversity loss; it has significant toxicological consequences for humans, plants, livestock (Malbert-Colas et al 2020). Abd El Azim Egyptian Journal of Biological Pest Control (2022) 32:4 heterorhabditids have dorsal teeth which help them to enter the insect intersegmental membranes (Burnell et al 2000). Nuclear genes have been used extensively, including the external non-transcribed spacer (NTS), the small subunit (SSU) or 18S, the internal transcribed spacer (ITS) region that separates rDNA-coding regions (Khashaba and Abdelazim 2021) composed of ITS-1, 5.8S, and ITS-2; and the large subunit (LSU) or 28S (Lulamba and SerepaDlamini 2020)
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