Background Isolation of novel species of entomopathogenic nematodes (EPNs) with biocontrol potential against important insect pests is very important for the sustainable management of economic pests damaging food crops and providing protection to the agricultural environment. This study was aimed to new indigenous EPN isolates from Egyptian agricultural soils and studies its biocontrol potential for further use in the biological control programs. Five out of 15 soil samples obtained from a farm located at the Cairo-Alexandria desert highway was positive for the presence of EPN, using the greater wax moth baiting method. Results Sequencing of the internal transcribed spacer (ITS) region of 4 of the nematode isolates suggested that they belong to the species Heterorhabditis indica. However, one isolate does not show a high similarity to any of the H. indica previously recorded in the database of the Gen Bank and hence was identified as a new Heterorhabditis species and was deposited at the National Center for Biotechnology Information (NCBI) and registered under accession no. (OP555450) under the name of Heterorhabditis alii. This new species was also registered in the ZooBank under the registration link of: LSID urn: lsid: zoobank.org: act: 306F9D57-CC30-4B8E-8B19-4F0E42B08F34. No males were found in this species. Morphological characterization using the light microscope (LM) and scanning electron microscope (SEM) confirmed the identification of this nematode as a new species of the genus Heterorhabditis. Moreover, virulence of this new species against the fall armyworm (FAW), Spodoptera frugiperda (Smith 1797) (Lepidoptera: Noctuidae) was tested in comparison with the foreign EPN species, Heterorhabditis bacteriophora (HP88) and the local Heterorhabditis indica (Mango 2 isolate) and proved to be more effective against this devastative insect pest than the two compared species. Conclusions The present study found out a new species of the EPN genus, Heterorhabditis in Egypt. Our results were confirmed by both morphological and molecular analyses. The efficacy of this new species against the FAW proved to be a potent and safe biocontrol agent that can be used in biological control programs against this invasive insect pest of corn in Egypt and other global countries.

The retreat of glaciers in Antarctica has increased in the last decades due to global climate change, influencing vegetation expansion, and soil physico-chemical and biological attributes. However, little is known about soil microbiology diversity in these periglacial landscapes. This study characterized and compared bacterial and fungal diversity using metabarcoding of soil samples from the Byers Peninsula, Maritime Antarctica. We identified bacterial and fungal communities by amplification of bacterial 16 S rRNA region V3-V4 and fungal internal transcribed spacer 1 (ITS1). We also applied 14C dating on soil organic matter (SOM) from six profiles. Physicochemical analyses and attributes associated with SOM were evaluated. A total of 14,048 bacterial ASVs were obtained, and almost all samples had 50% of their sequences assigned to Actinobacteriota and Proteobacteria. Regarding the fungal community, Mortierellomycota, Ascomycota and Basidiomycota were the main phyla from 1619 ASVs. We found that soil age was more relevant than the distance from the glacier, with the oldest soil profile (late Holocene soil profile) hosting the highest bacterial and fungal diversity. The microbial indices of the fungal community were correlated with nutrient availability, soil reactivity and SOM composition, whereas the bacterial community was not correlated with any soil attribute. The bacterial diversity, richness, and evenness varied according to presence of permafrost and moisture regime. The fungal community richness in the surface horizon was not related to altitude, permafrost, or moisture regime. The soil moisture regime was crucial for the structure, high diversity and richness of the microbial community, specially to the bacterial community. Further studies should examine the relationship between microbial communities and environmental factors to better predict changes in this terrestrial ecosystem.

Climate change is modifying global biogeochemical cycles. Microbial communities play an integral role in soil biogeochemical cycles; knowledge about microbial composition helps provide a mechanistic understanding of these ecosystem-level phenomena. Next generation sequencing approaches were used to investigate changes in microbial functional groups during ecosystem development, in response to climate change, in northern boreal wetlands. A gradient of wetlands that developed following permafrost degradation was used to characterize changes in the soil microbial communities that mediate C cycling: a bog representing an undisturbed system with intact permafrost, and a younger bog and an older bog that formed following the disturbance of permafrost thaw. Reference 16S rRNA databases and several diversity indices were used to assess structural differences among these communities, to assess relationships between soil microbial community composition and various environmental variables including redox potential and pH. Rates of potential CO2 and CH4 gas production were quantified to correlate sequence data with gas flux. The abundance of organic C degraders was highest in the youngest bog, suggesting higher rates of microbial processes, including potential CH4 production. In addition, alpha diversity was also highest in the youngest bog, which seemed to be related to a more neutral pH and a lower redox potential. These results could potentially be driven by increased niche differentiation in anaerobic soils. These results suggest that ecosystem structure, which was largely driven by changes in edaphic and plant community characteristics between the undisturbed permafrost bog and the two bogs formed following permafrost thaw, strongly influenced microbial function. (C) 2017 Elsevier Masson SAS. All rights reserved.