Description ofOscheius cyrusn. sp. (Nematoda: Rhabditidae) as new entomopathogenic nematode from Iran

Abstract

A new species of the genus Oscheius, Oscheius cyrus n. sp., collected in the moist soils taken from forest heights in the north of Iran, is recorded. A comprehensive description, comprising molecular (internal transcribed spacer (ITS), 18S, and 28S rDNA genes) information, morphometrics data, light microscope and scanning electron microscope images, is supplied. The species resembles Oscheius myriophilus. However, the highest ranges for female body length, female tail, infective juvenile tail length, median bulb, absence of epiptygma and lateral field incisures number vary. The new species was distinguished from Oscheius insectivorus by the general lip region. The male was not found. Molecular analysis showed that the new species has the most similarity to O. myriophilus both in the ITS and 18S regions. Morphological and molecular data confirmed its belonging to the Insectivora-group. Furthermore, the species of Ochrobactrum pseudogrignonense was reported as a dominant associated bacterium of the new Oscheius species. Finally, the mortality of the host after seven days varied from 20% to 82.5%, depending on nematodes’ concentration.

Genotypic relationships and phylogeography of the genus Oscheius (Rhabditidae: Rhabditomorpha) with a new entomopathogenic isolate of Oscheius tipulae Lam and Webster, 1971

“…Based on the clustering and placement of the taxa of the large subunit, the present analyses agreed with those of previous studies carried out [5,13,19,21,44] using large subunit 28s rDNA, the taxa O. shamimi (MN381940), O. safricanus (KM270116), and O. rugaoensis (KT884891) with O. insectivorus (MT506350), O. myriophilus (MK418537; MN389671), O. necromenus (KY366264) consistently occupied the same position and clustered together (Fig. 4, 5).…”

“…The systematic position of the genus was frequently discussed and revised by several workers in the past [1,5,17,19]. The genus was divided into two species groups viz., insectivorusgroup and Dolichura-group [36,40].…”

“…The genus was divided into two species groups viz., insectivorusgroup and Dolichura-group [36,40]. The studies conducted lately on the species of Oscheius by the workers [1,13,19]. Recently, the genus was splitted into two subgenera viz., Oscheius and Dolichorhabditis Andrássy, 1983 [1].…”

<i>Oscheius</i> sp. KHA501の病原性および昆虫病原性細菌との関係性

“…The entomopathogenicity of Oscheius nematodes is inherently less pronounced compared to that of the conventional EPNs like Steinernema and Heterorhabditis (Torrini et al, 2015). Since an obligatory symbiotic relationship similar to that of EPNs and their symbiotic bacteria is not observed, the pathogenic characteristics of Oscheius nematodes are believed to depend on the presence of their associated entomopathogenic bacteria (Serepa and Gray, 2014;Lephoto et al, 2015;Castro-Ortega et al, 2020;Kuhestani et al, 2022). The exact nature of the interaction between entomopathogenic bacteria and Oscheius nematodes remains insufficiently elucidated.…”