Phylogenetic relationships of Steinernema Travassos, 1927 (Nematoda: Cephalobina: Steinernematidae) based on nuclear, mitochondrial and morphological data

Nadler, Steven A.; Bolotin, Eugene; Stock, S. Patricia

doi:10.1007/s11230-005-9009-3

Cited by 95 publications

(76 citation statements)

References 47 publications

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“…This division is supported by the morphology of the infective juvenile, morphology of the sperm cells in the uterus and molecular analysis based on nuclear and mitochondrial rDNA (SSU, LSU; 12S, cox 1). Despite the fact that the composition of the five clades in Nadler et al (2006b) and Spiridonov et al (2004) do not exactly correspond, the species of the present study are consistent with both studies. Here, we discuss if these clades can also be characterised by gonoduct morphology.…”

Section: Discussionsupporting

confidence: 81%

“…Based on morphology and multi-gene molecular analysis, the genus Steinernema has been subdivided into five major clades (Stock et al, 2001;Spiridonov et al, 2004;Nadler et al, 2006b): I, 'intermedium-affine'; II, 'carpocapsae-tami-scapterisci'; III, 'feltiae-krausseioregonense'; IV, 'bicornutum-ceratophorum-riobrave'; and V, 'glaseri-arenarium-karii-longicaudatum'. This division is supported by the morphology of the infective juvenile, morphology of the sperm cells in the uterus and molecular analysis based on nuclear and mitochondrial rDNA (SSU, LSU; 12S, cox 1).…”

Section: Discussionmentioning

confidence: 99%

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The structure of the female reproductive system of nematodes from the genus Steinernema (Rhabditida: Steinernematidae)

Zograf¹,

Bert

Borgonie

2008

Nematol

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Summary -Females of six species of nematodes from the genus Steinernema (S. affine, S. arenarium, S. bicornutum, S. carpocapsae, S. feltiae and S. glaseri) were studied using light microscopy. Investigation of the gonoduct morphology was completed with ultrastructural data for S. carpocapsae and S. feltiae. Except for S. bicornutum, all species studied show an overall similarity in reproductive system architecture, i.e., a swollen proximal region of the ovaries, an oviduct consisting of irregular rows with two to four cells in cross-section and a uterus divided into two morphologically distinguishable parts (except S. carpocapsae). Such a gonoduct structure is distinctive from any other known nematode gonoduct, especially the particular arrangement of the oviduct cells in mostly long irregular rows with two to four cells in cross-section (except S. bicornutum), which is, according to current knowledge, unique within the Rhabditida. These results indicate the coherence of the genus Steinernema as shown from other morphological and molecular studies. The distal swelling of the uterus is considered to be a spermatheca-uterus complex that possibly functions to store and activate sperm and as a fertilisation chamber. The diversity of the cellular architecture of the Steinernema gonoduct provides valuable information for the delineation of species within a morphologically conserved genus. Furthermore, limited results point to a congruence between the gonoduct characters and current molecular phylogenetic hypothesis within Steinernema. Future studies in this direction must ultimately lead to a better understanding of evolutionary processes within the genus.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

The structure of the female reproductive system of nematodes from the genus Steinernema (Rhabditida: Steinernematidae)

Zograf¹,

Bert

Borgonie

2008

Nematol

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“…The other strain of the species, S. feltiae 4CFMO, showed significant mortality in male-male conflicts (although at 50% of pairs it was lower than the other species), pointing to intra-specific as well as interspecific variation in killing amongst steinernematids. The species tested represent three of the five Steinernema clades, (Nadler et al, 2006), clades II, III and V ( Table 1), indicating that it is an ancient character of the genus (or, less likely, that it has evolved independently several times). In additional studies in our laboratory, male-male killing was not detected in Steinernema bicornutum (Clade IV; n = 21) (Brendan Igoe, personal communication).…”

Section: Discussionmentioning

confidence: 99%

Interference competition in entomopathogenic nematodes: male Steinernema kill members of their own and other species

O’Callaghan

Zenner

Hartley

et al. 2014

International Journal for Parasitology

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a b s t r a c tThere is evidence of competition within and between helminth species, but the mechanisms involved are not well described. In interference competition, organisms prevent each other from using the contested resource through direct negative interactions, either chemical or physical. Steinernema spp. are entomopathogenic nematodes; they enter a living insect host which they kill and consume with the aid of symbiotic bacteria. Several studies have demonstrated intra-and interspecific competition in Steinernema, mediated by a scramble for resources and by incompatibility of the bacterial symbiont. Here we describe a mechanism by which male Steinernema may compete directly for resources, both food (host) and females, by physically injuring or killing members of another species as well as males of their own species. A series of experiments was conducted in hanging drops of insect haemolymph. Males of each of four species (Steinernema longicaudum, Steinernema carpocapsae, Steinernema kraussei and Steinernema feltiae), representing three of the five phylogenetic clades of the genus, killed each other. Within 48 h, up to 86% of pairs included at least one dead male, compared with negligible mortality in single male controls. There was evidence of intraspecific difference: one strain of S. feltiae (4CFMO) killed while another (UK76) did not. Males also killed both females and males of other Steinernema spp. There was evidence of a hierarchy of killing, with highest mortality due to S. longicaudum followed by S. carpocapsae, S. kraussei and S. feltiae. Wax moth larvae were co-infected with members of two Steinernema spp. to confirm that killing also takes place in the natural environment of an insect cadaver. When insects were co-infected with one infective juvenile of each species, S. longicaudum males killed both S. feltiae UK76 and Steinernema hermaphroditum. Wax moths co-infected with larger, equal numbers of S. longicaudum and S. feltiae UK76 produced mainly S. longicaudum progeny, as expected based on hanging drop experiments. Ó

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“…The nematodes were allowed to migrate through the sand column for periods ranging from 4 to 48 h, after which the insects were removed from the column, washed to remove adhering IJs and incubated at the Campbell et al (2003). b Spiridonov et al (2004) and Nadler et al (2006). assay temperature.…”

Section: Experimental Infectionsmentioning

confidence: 99%

Sex ratios and sex-biased infection behaviour in the entomopathogenic nematode genus Steinernema

Alsaiyah

Ebssa

Zenner

et al. 2009

International Journal for Parasitology

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a b s t r a c tIn experimentally infected insects, the sex ratio of first generation nematodes of five species of Steinernema was female-biased (male proportion 0.35-0.47). There was a similar female bias when the worms developed in vitro (0.37-0.44), indicating that the bias in these species is not due to a lower rate of infection by male infective juveniles (IJs). Experimental conditions influenced the proportion of males establishing in insects, indicating that male and female IJs differ in their behaviour. However, there was no evidence that males are the colonising sex in any species, contrary to what has previously been proposed. Time of emergence from the host in which the nematodes had developed influenced sex ratios in experimental infections. In three species (Steinernema longicaudum, Steinernema glaseri and Steinernema kraussei), early emerged nematodes had a higher proportion of males than those that emerged later, with the reverse trend for Steinernema carpocapsae and Steinernema feltiae. In a more detailed in vitro study of S. longicaudum, the proportion of males was similar whether or not the nematodes passed through the developmentally arrested IJ stage, indicating that the female bias is not due to failure of males to exit this stage. The sex ratio in vitro was independent of survival rate from juvenile to adult, and was female-biased even when all juveniles developed, indicating that the bias is not explained by failure of males to develop to adults. The female-biased sex ratio characteristic of Steinernema populations appears to be present from at least the early juvenile stage. We hypothesise that the observed female bias is the population optimal sex ratio, a response to cycles of local mate competition experienced by nematodes reproducing within insect hosts interspersed with periods of outbreeding with less closely related worms following dispersal. Ó

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Phylogenetic relationships of Steinernema Travassos, 1927 (Nematoda: Cephalobina: Steinernematidae) based on nuclear, mitochondrial and morphological data

Cited by 95 publications

References 47 publications

The structure of the female reproductive system of nematodes from the genus Steinernema (Rhabditida: Steinernematidae)

The structure of the female reproductive system of nematodes from the genus Steinernema (Rhabditida: Steinernematidae)

Interference competition in entomopathogenic nematodes: male Steinernema kill members of their own and other species

Sex ratios and sex-biased infection behaviour in the entomopathogenic nematode genus Steinernema

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