Termite nematode Neosteinernema longicurvicauda Nguyen & Smart, 1994

By Khuong B. Nguyen
University of Florida

 Head of a termite parasitized by the nematode

 Description males , FemalesInfective juvenilesType hostBionomics , BiocontrolMorphometrics


Males: Body curved ventrally or C-shaped when heat-killed. Lateral field present with one incisure, sometimes indistinct. Stoma shallow, cheilorhabdions prominent; other parts of stoma appear funnel-shaped. By light microscopy, the walls of the stoma, especially the dorsal side, appear thickened anteriorly and raised to form a subtriangular structure which in lateral view resembles a dorsal and ventral tooth. Esophagus steinernematoid but somewhat thinner and more elongate than in Steinernema. Esophago-intestinal valve pronounced. Excretory pore at or anterior to middle of esophagus; excretory duct sclerotized anteriorly. Gonad monorchic, reflexed. Spicules paired, foot-like in shape, a prominent hump present on dorsal side of spicules(Fig. 1); spicule head enlarged anteriorly; spicule tip pointed, slightly curved ventrally; two prominent ribs present in each spicule. Gubernaculum long (gubernaculum/spicule ratio 0.97), 32% of males with gubernaculum equal to or longer than spicule (Fig. SEM). Usually the proximal end of gubernaculum is difficult to see in situ but after they are dissected out they can be seen and measured accurately. Cuticle of cloacal area forming a tubus around spicules. Genital papillae, 13 or 14 pairs and one single, ventral, preanal papilla; eight pairs preanal, mostly subventral, more or less variable in position, one pair in anal area, two or three pairs caudal, subventral and two pairs caudal, subdorsal.Phasmids prominent.Tail conoid, tail tip digitate with some variations, especially on young males.

No second generation males were found.

 Posterior region of a female

Females: (Fig. 2)  Anterior region similar to male but much larger. Body spiral, usually found in surrounding medium next to termite cadavers. Cuticle annulated. Lateral fields not observed. Head truncate or rounded. Labial papillae six, prominent, many additional papillae-like structures often present together with labial papillae. Stoma as in male but structures larger and more prominent; raised ring prominent in stoma apearing tooth-like in lateral view. Esophagus typical of steinernematids. Gonads didelphic, amphidelphic, reflexed. Epiptygma absent.Tail curved, longer than body width at anus, tail length divided by body width at anus about 1.40 (1.10-1.70) (FEMALE.SEM)  . Phasmids prominent, on a protuberance, located in posterior half of tail. Eggs are not laid but hatch inside the body, and the juveniles become infective stage before exiting the female.

Females emerged from termites

 No second generation females were found.

Infective juveniles: (Fig. 3) Juveniles become infective stage juveniles before emerging from female. Body thin, elongate (a=39), well striated. Sheath (second stage cuticle) present but sometimes lost.Head region smooth, mostly slightly enlarged. Oral aperture closed, triradiate; lips six. Labial papillae not observed; four cephalic papillae prominent, situated well behind anterior end. Amphids large, slit like, post-labial in position but anterior to cephalic papillae. Esophagus degenerate, basal bulb elongate with valve, esophago-intestinal valve present but sometimes obscure. Excretory pore prominent; excretory duct long, sinuous, seen clearly on living specimens. A sclerotized structure associated with excretory duct just anterior to excretory cell, appearing as two black dots in lateral view. Lateral field at mid body wider than one third of body width, usually only two border striae seen clearly; eight smooth bands and nine incisures prominent in anterior and posterior regions. Tail elongate, 10 times (8-11) (Table 1) as long as body width at anus, always curved ventrally in posterior end. Average tail length as long as esophagus length. Phasmids prominent, slit-like (JUVENILE.SEM). Left and right phasmids not at the same level, usually situated 25 to 50 m posterior to anus, and occupying 3 or 4 lateral bands.


In the head of the termite Reticulitermes flavipes (Koller) collected near Lake Okeechobee, Florida, USA.


Neosteinernema longicurvicauda has been reported only from the termite Reticulitermes flavipes in Florida, the United States.


The bionomics and host relationships were report briefly by Nguyen and Smart, 1994. The nematode developed only in the head of the termite. The adults emerged when the tissue of the termite began to decay. The number of adults in each termite was reported as from 1-4 (26% with one nematode, 40 % with two, 20 % with three and 14 % with 4). Twenty of 35 termites studied harbored both males and females, and 15 harbored either males or females. Where only one sex was present, no reproduction occured. When both males and females were present, the females, after emerging, moved a short distance away from the termite cadavers, assumeed a spiral shape, and became immobile. The female retained all eggs that hatched, and the juveniles underwent two molts to become infective juveniles. When most of the juveniles became infective juveniles, they moved vigorously, broke through and emerged from the then female cadaver in the region of tail or stoma. No first- and second-stage juveniles were observed in or surrounding termite cadavers. During developement of juvenile, large number of bacterial cells were observed in the female bodies. No second generation was observed.


The bacteria associate with this nematode were not reported. The bacteria were isolated by the authors for in vitro rearing but were not identified.


A patent has been granted to Miles Inc., Vero Beach, Florida  for the use of the nematode to control termite . So far, no biological control details have been released.

Table 1. Morphometric characters.
Character1 infective juvenile(50) female(25) male(25)
Body length 92 SD 60 (789-1,084) 3,444 SD 784 (2,250-4,766) 1,236 SD 228 (854-1,084)
Greatest width 24 SD 2 (20-31) 177 SD 37 (122-250) 97 SD 18 (67-140)
Stoma length 8 SD 1.3 (6-11) 5.5 SD 1 (5-8)
Stoma width 14 SD 1.6 (11-17) 7.2 SD 1.4 (5-11)
EP 68 SD 4 (61-76) 112 SD 16 (84-147) 82 SD 2 (59-103)
EPW 18 SD 2 (10-20)  44 SD 5 (33-52)
NR 107 SD 7 (92-125) 177 SD 21 (150-225) 126 SD 15 (103-156)
ES 164 SD 10 (144-188) 262 SD 28 (219-334) 187 SD 22 (147-227)
Testis flexure 277 SD 55 (178-394)
Tail length (T) 167 SD 11 (141-190) 105 SD 12 (88-134) 48 SD 6 (36-63)
ABW 17 SD 1 (14-20)  76 SD 10 (63-103)  60 SD 10 (41-78)
T/ABW 10 SD 1 (8-11)  1.4 SD 0.1 (1.1-1.7)
Digitate part of tail 8 SD 3 (3-14)
Spicule length (SP) 61 SD 4 (52-67)
Spicule width 13 SD 1 (11-15)
Gubern length (GU) 9 SD 4 (52-66)
Gubern width 9 SD 1 (8-13)
Vulva % 55 SD 3 (49-60)
a 39 SD 3 (30-46) 
b 5.6 SD 5 (5-7) 
c 5.5 SD 0.3 (4.7-6.5)
D%=EP:ES x 100 41 SD 2 (38-46)  43 SD 7 (31-64) 44 SD 6 (30-54)
E%=EP/T x 100 41 SD 3 (37-48) 
SW=SP/ABW 1.03 SD 0.18 (0.8-1.5)
GS=GU/SP 0.97 SD 0.06 (0.84-1.08)

1 EP = distance from anterior end to excretory pore; EPW = body width at excretory pore; NR = distance from anterior end to nerve ring; ES = distance from anterior end to base of esophagus; T = tail; ABW = anal body width; Gubern= gubernaculum; a = body length divided by greatest width; b = body length divided by ES; c = body length divided by T.


NGUYEN, K. B., & SMART, G. C. Jr. (1994). Neosteinernema longicurvicauda n. gen. n. Sp. (Rhabditida: Steinernematidae), a parasite of the termite Reticulitermes flavipes (Koller). Journal of Nematology 26:162-174.
Nguyen, K. B. (February 1999). "Taxonomy of Entomopathogenic Nematodes" .Available:

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