Steinernema feltiae

(Filipjev, 1934)Wouts, Mracek, Gerdin & Bedding, 1982


Females : Cuticle smooth, lateral field absent. Lip region rounded or truncate with six lips, each with one labial papilla at its tip. Four cephalic papilla present. Amphids obscure. Cheilorhabdions well sclerotised. Prorhabdion seen as small dots posterior to cheilorhabdions. Other rhabdions degenerate forming a funnel-shaped structure. Esophagus short in relation to body size. Typical for steinernematids. Basal bulb pyriform. Cardia present. Excretory pore at level of metacorpus or somewhat anterior . Excretory glands displacing anterior part of intestine dorsally. Gonads paired, reflexed. Uterus and spermatheca located centrally between vulva and flexure, ovaries located dorsally beyond flexure, terminating ventrally in opposite body half. Vulva lips protruding with small epiptygma. Rectum and anus distinct. Posterior anal lip usually conspicuously enlarged. Tail tapering rapidly to rounded body end with mucronated terminus. Maximum body length observed: 7 mm.

Males: Cuticle smooth, lateral fields absent. Anterior region similar to female. Cardia large. Testis reflexed. Spicules (FIG.SEM) slightly curved. Spicule head elongate, ratio spicule length/spicule width larger than 1.5, usually twice as long as wide. Shaft present short. Blade moderately curved. Velum not observed. Spicule terminus bluntly rounded. In ventral view, gubernaculum tapering anteriorly, a narrow neck present. Cuneus short, Y-shaped, not reaching posterior end of corpus. Eleven pairs and one large ventral pre-anal genital papillae present and located as follows: five pairs in subventral row anterior to cloaca, two pairs adanal, one pairs lateral, two pairs subventral subterminal and one pair subdorsal on tail. Tail tapering to rounded body terminus with fine, long mucron. Bursa absent.

Measurements Male : (n = 10) L = 934 / micrometers (um (850-1000); greatest width = 75 um (60-90); esophagus length = 130 um (110-150); basal bulb width 28 um (25-32); body width at level of basal bulb = 50 um (40-65); distance of excretory pore from anterior end = 75 um (65-85); testis length =575 um (475-675); spicule length = 62 um (60-65); gubernaculum = 40 um (35-45); tail length without mucron = 27 um (22-32); mucron length = 10 um (8-15). (From Wouts, 1980)

 Infective juveniles: Body slender, tapering regularly from base of esophagus to anterior end and from anal area to tail terminus. Cuticle with indistinct transverse annulation, most clearly visible in early development when still surrounded by L2 cuticle, and in late development when growth resumes in new host. Lateral field distinct, with eight ridges resulting in nine lateral lines, starting short distance from head, terminating on tail, the upper and lower submarginal ridges reduced. Deirids at level of hemizonid, small, with distinct subcutaneous supporting structure. Phasmids small, on posterior half of non-hyaline portion of tail. Lip region smooth, generally not set off. Cheilostom a narrow pore in face view surrounded by six labial papillae, six indistinct cephalic papillae, and two amphids. Protostom-telostom triangular in shape anteriorly, changing to triradiate posteriorly. Esophagus long and narrow, with triradiate lumen, occupying 1/3-1/4 body-width, distinctly narrower at level of nerve ring, terminating in valved bulb. Nerve ring distinct. Excretory pore distinct, located at level of mid esophagus. Excretory duct long, usually distinct; ventral excretory glands displace basal bulb and anterior end of intestine. Hemizonid at level of basal bulb. Cardia present. A pouch of bacteria enclosed by intestinal wall immediately below cardia. Hemizonion variable in position, usually at level of posterior end of bacterial pouch. Lumen of intestine narrow or closed. Intestinal wall dark with globules. Rectum long and narrow. Anus distinct. Tail conical with pointed terminus.

Measurements (n=20): Length = 880 um (micrometers) (750-950); width = 25 um (22-27); stoma length = 1.32 um (I 1.5-15.5); esophagus length 135 urn (115-150); basal bulb width= 10.8 um (9-12); length of bacterial pouch in intestine = 29 um (18-37); gonad length = 190 um (130-230); tail length = 83 um (71-92); distance from anterior end to excretory pore = 62 um (53-67), to nerve ring = 100 um (89-108); body width at level of basal bulb = 23 um (2125); body width at level of anus - 15.6 um (15-17); distance of phasmids from tail terminus = 52 um (45-67). (From Wouts, 1980)

Differential diagnosis:

- Infective juveniles body length averaging 880 micrometers (750-950 um)

- Males with long spicules head and long mucron; spicule length about 70 um


Bovien, P. 1937. Some type of association between nematodes and insects. Videnk. Meddr Naturh. Foren. 101: 1-114.

Filipev, I. N. 1934. Eine newe art der gattung Neoaplectana Steiner nebst  Bemerkungen uber die systematishe sellung der letzteren. Magasin de parasitologie de l'Institut zoologique des Sciences de
l' USSR.  IV. 1934229-240.

Wout, W. M. 1980. Biology, life cycle and redescription of Neoaplectana bibionis Bovien, 1937
(Nematoda: Steinernematidae). Journal of Nematology 12:62-72.

This document was constructed and is maintained by KHUONG B. NGUYEN
Entomology & Nematology Department
University of Florida