The strength of sequence-related amplified polymorphism (SRAP) in comparison to random amplified polymorphic DNA (RAPD) in determining the genetic polymorphism among seven species of entomopathogenic nematodes (Steinernematidae) was tested. Nine RAPD and 12 SRAP primer pair's combinations were used. The number of polymorphic bands and the polymorphism percentages was high in SRAP analysis (97 out of 107 bands were polymorphic (90.6%)) compared to RAPD (65 out of 89 bands were polymorphic (73%)). The highest number of RAPD bands was recorded for OPE-A-07 primer (14 band) while OPE-D-20 was scored the lowest band number (7 bands). The SRAP primers Me3-em2 registered the highest number of bands (13 bands) while Me3-em3and Me2-em2 showed the lowest band number (6 bands). The genotype-specific SRAP and RAPD markers for the different ENP species were recorded. The highest number of SRAP specific markers (7 markers) was scored for Steinernema glaseri, then 4 markers for S. abbasi 2 followed by S. riobrave (3 markers), 1 marker for S. abbasi 1, S. riobrave recorded the highest number of specific RAPD marker (4 specific markers) followed by S. carpocapsae DD 136 and S. glaseri (two specific markers), then only 1 specific marker for S. abbasi 1. Based on the data obtained from RAPD and SRAP analysis, the dendrogram was created to clarify the genetic distances among different species of the studied entomopathogenic nematodes. The present study indicated that SRAP was more powerful than RAPD analysis for detecting the genetic polymorphism among closely related species of nematodes. The genotype-specific markers detected from both RAPD and SRAP can be used in future biological control programs.

Entomopathogenic nematodes (EPNs) are a group of biological control agents that are characterized by their ability to search for hosts, safety to non-target insects and environment, and their ability to be used combined with agricultural chemicals. The objectives of this study were to isolate EPNs from agricultural soil in Egypt and study their virulence against the great wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae), for further use in biological control program. Two out of 20 soil samples collected from orchards cultivated with olives and mango were positive for the presence of EPNs, using the Galleria baiting technique. The positive soil samples were sandy clay loam. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolates obtained belong to Heterorhabditis indica. The ITS sequences were submitted to the National Center for Biotechnology Information (NCBI) and registered under the accession nos. MH553167 and MK300683. The efficacy of the isolates was tested on G. mellonella, using different nematodes’ concentrations. Using 50 IJs/larvae from H. indica Aborawash and ERSAG2 showed 100 and 86% mortality rate after 48 h, respectively. The penetration rate reported in dead G. mellonella was 40% at H. indica Aborawash, while it was 35% in case of ERSAG2.

Background The aims of the present study were to isolate and identify native entomopathogenic fungi, Beauveria bassiana from the Egyptian soil and to evaluate the artificial establishment of B. bassiana as endophytes in rice plants through seeds immersion. Results Ten soil samples were collected from different cultivated fields at the Ismailia Governorate. Only one sample was positive with a ratio of 10%. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolate obtained from the soil sample belongs to B. bassiana and was registered under the accession no. MN337282. To test the endophytic colonization of B. bassiana, rice seeds were soaked by B. bassiana with a concentration of 5 × 107 spores/ml, to test when B. bassiana become an endophyte in rice plants. The plants were examined for endophytic presence of B. bassiana, 30 days post treatment. PCR amplification using fungal specific primers for a conserved region of β-tubulin gene yielded identical 360 bp products from both B. bassiana and rice treated plants. Conclusion The results showed that seeds immersion with a conidial suspension proved to be a good method to introduce B. bassiana into rice leaves to protect the rice plants against stem borers.

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Background Entomopathogenic nematodes (EPNs) are a group of nematode families, have the ability to search for their hosts, and are considered as promising biological control candidates for insect pests, providing protection to non-target organisms and the environment. Results This study was conducted to isolate indigenous EPN isolates from Egyptian agricultural soils for further use in biological control programs and study their genetic polymorphism among the previously isolated isolates under accession no. MH553167 and MK300683 and the new isolate (MH496627), using the start codon targeted (SCoT) marker. One out of 15 soil samples obtained from a banana cultivated field was positive for the presence of EPNs, using the Galleria baiting method. Morphological analysis and sequencing of the internal transcribed spacer (ITS) region suggested that the isolate obtained belongs to Heterorhabditis indica. The sequence of the ITS was submitted to the National Center for Biotechnology Information (NCBI) and registered under accession no. MH496627. Ten SCoT primers were used in the study; the polymorphic bands were 68 out of 76 with 89% as polymorphism percentage. The highest numbers of bands were 10 bands generated by SCoT 1 and SCoT 18 while SCoT 48 and SCoT 60 recorded the lowest band number (5 bands). Conclusions The present study is considered as a preliminary study to demonstrate the effectiveness of the SCoT marker for the first time in assessing genetic relationships in EPNs.

Abd ElAzim et al (2019) Genetic polymorphism among seven entomopathogenic nematode species (Steinernematidae) revealed by RAPD and SRAP analyses.

To estimate the genetic variation among five Egyptian clover cultivars, Random amplified polymorphic DNA (RAPD) and sequence-related amplified polymorphism (SRAP) analyses were employed. Sixteen RAPD and six SRAP primers were used in the present study, a total of 34 and 12 bands showed 24.8 and 60% polymorphism percentage. The highest number of RAPD bands was recorded for primers OPE-B-07 (13 bands), followed by OPE-K-04 (12 bands), while the lowest was scored for OPE-B-05 (5 bands). For the SRAP Primers Me1-em2, Me3-em2 and Me3-em4 recorded the highest number of bands (four bands), followed by three bands for Me1-em1and Me3-em3, primer Me3-em1 recorded the lowest band number (two bands only). The dendrogram built based on combined data from RAPD and SRAP analyses clarify the genetic distances among the five Egyptian clover cultivars.

Background Entomopathogenic nematodes (EPNs) are widely used in biological control for soil-dwelling stages of many insect pests that are characterized by their safety to most non-target organisms and to the environment. Results The objectives of the present study were isolation of EPNs from agricultural soil in Egypt for further use in biological control programs and study the genetic variation among them using the molecular marker inter-simple sequence repeats (ISSR). Three out of 25 soil samples collected from fields cultivated with strawberry, tangerine, and pumpkin were positive for the presence of EPNs, using the Galleria baiting technique. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolates obtained belong to Heterorhabditis sp. The ITS sequences were submitted to the National Center for Biotechnology Information (NCBI) and registered under accession nos. MH553165, MH553168, and MH553169. Six ISSR primers were used. The numbers of polymorphic bands were 42 out of 56, and the polymorphism percentage was 75%. The highest number of bands was 12 bands generated by primer ISSR8 followed by UBC-809 (11 bands) while recorded the lowest band number (4 bands), the percentage of polymorphism ranged from 40% (ISSR1) to 100% (ISSR6). Conclusion ISSR marker can be considered a good marker to study genetic diversity and detecting the genetic polymorphism among the nematodes species.