5. Additional parts of stoma forming an asymmetrical funnel with
thick anterior end. The esophagus rhabditoid with metacorpus
is swollen slightly, narrow isthmus enclosed by nerve ring, and
large basal bulb with reduced valve.
6. Esophagointestinal valve commonly pronounced.
7. Reproductive system is generally didelphic, amphidelphic, and
reflexed. Vulva at midbody, occasionally on a protuberance,
with or without epiptygma.
8. Females oviparous or ovoviviparous with juveniles maturing up
to the infective stage (IJ) earlier to emerging from the body of
the female.
9. Tail may occur with or without noticeable phasmids and are
usually longer or shorter than anal body width.
Male
1. Smaller than female.
2. Anterior end usually with six labial papillae, four large cephalic
papillae, and usually with perioral disc.
3. Esophagus similar to that of female.
4. Testis single, reflexed; spicules paired; gubernaculums long,
sometimes as long as spicule; bursa absent.
5. Tail tip rounded, digitate, or mucronate.
6. One single and 10–14 pairs of genital papillae present with
7–10 pairs precloacal.
Infective Juvenile
1. Generally the stoma is collapsed.
2. They have a lean body with or without a sheath (cuticle of
second-stage juvenile).
3. Predominantly the cuticle is annulated.
4. Lateral fields comprise 4–9 incisures and 3–8 smooth ridges.
5. Esophagus and intestine seem to be reduced. Separate excretory pores are present.
6. Tail is usually conoid or filiform.
7. Phasmid inconspicuous.
Identification
of Steinernema Species
Species of Steinernema can be recognized with the succeeding key,
but identity should be confirmed by paralleling its morphometrics
with the data from original descriptions.
Ratios and abbreviations used in the following key are:
IJ ¼ infective juvenile.
EP ¼ distance from anterior end to excretory pore.
ES ¼ esophagus length.
SP ¼ spicule length.
74
Laboratory Techniques for Entomopathogenic Nematodes
thick anterior end. The esophagus rhabditoid with metacorpus
is swollen slightly, narrow isthmus enclosed by nerve ring, and
large basal bulb with reduced valve.
6. Esophagointestinal valve commonly pronounced.
7. Reproductive system is generally didelphic, amphidelphic, and
reflexed. Vulva at midbody, occasionally on a protuberance,
with or without epiptygma.
8. Females oviparous or ovoviviparous with juveniles maturing up
to the infective stage (IJ) earlier to emerging from the body of
the female.
9. Tail may occur with or without noticeable phasmids and are
usually longer or shorter than anal body width.
Male
1. Smaller than female.
2. Anterior end usually with six labial papillae, four large cephalic
papillae, and usually with perioral disc.
3. Esophagus similar to that of female.
4. Testis single, reflexed; spicules paired; gubernaculums long,
sometimes as long as spicule; bursa absent.
5. Tail tip rounded, digitate, or mucronate.
6. One single and 10–14 pairs of genital papillae present with
7–10 pairs precloacal.
Infective Juvenile
1. Generally the stoma is collapsed.
2. They have a lean body with or without a sheath (cuticle of
second-stage juvenile).
3. Predominantly the cuticle is annulated.
4. Lateral fields comprise 4–9 incisures and 3–8 smooth ridges.
5. Esophagus and intestine seem to be reduced. Separate excretory pores are present.
6. Tail is usually conoid or filiform.
7. Phasmid inconspicuous.
Identification
of Steinernema Species
Species of Steinernema can be recognized with the succeeding key,
but identity should be confirmed by paralleling its morphometrics
with the data from original descriptions.
Ratios and abbreviations used in the following key are:
IJ ¼ infective juvenile.
EP ¼ distance from anterior end to excretory pore.
ES ¼ esophagus length.
SP ¼ spicule length.
74
Laboratory Techniques for Entomopathogenic Nematodes