This document provides an outline about entomopathogenic nematodes. It discusses their history, life cycle, mode of action, host range, advantages, and limitations. Entomopathogenic nematodes are beneficial roundworms that kill insect pests. They enter insect hosts and release symbiotic bacteria that multiply and kill the insect within 48 hours. The nematodes then complete their life cycle inside the insect cadaver.

1. By Shariqa Aisha.
University of Kashmir
Department of Bioresources

2. Outline
 Introduction
 History
 Global Distribution
 Pathogenicity
 Life cycle
 Mode of Action
 Host Range
 Mode of Application
 Advantages
 Limitations

3.  Nematodes are simple round worms.
 These are colorless, unsegmented, and lacking
appendages.
 Nematodes mat be free-living, predaceous, and
parasitic.
 Nematodes pathogenic to insects are referred to as
Entomopathogenic Nematodes.
 they possess an optimal balance of biological
control.
 Entomopathogenic nematodes are extraordinarily
lethal to many important insect pests, yet are safe
for plants and animals.

4.  The first Entomopathogenic Nematode was described by Steiner in
1923 as Aplectana kraussei ( Steinernema kraussei).
 In 1928, Dutky found Neoaplectana carpocapsae.
 In 1929, Steiner gave the systematic position of second
entomopathogenic nematode, Neoaplectana glaseri.
 Heterorhabiditis bacteriophora, was first time described In 1976 by
Pionar.
 The infective juvenile (IJ) stage, were found to transmit a specific Gram-
negative baterium in the anterior intestine to the homeceol of insect
hosts ( Poinar et. Al 1977).

6.  Entomopathgenic nematodes enter through
the insects natural body openings, the
mouth, anus, or respiratory inlets(spiracles).
 Heterorhabditis species penetrate through
the intersegmental membranes by stretching
away at these with a special tooth.
 In the insects blood, infective juvenile
releases a highly specialized symbiotic
bacterium.
 These symbiotic bacteria multiply rapidly
produce toxins that cause septicemia.

7.  Nematodes complete 2-3 generations inside the host.
 Over 100,000 nematodes exist an infected insect.
 The cycle of entry of infective juveniles into the insect host to
emerge of new batch of infective juveniles takes about 10-14 days.

9.  Simple life-cycle includes the egg, four juvenile stages
and an adult.
 Infective juvenile ( third stage) called dauer larvae is
resistant to environmental conditions.
 EPN locate their insect hosts in the soil by detecting
chemical cues such as excretory products and
carbobdioxide gradient.
 One generation from egg to egg typically takers from
4-7 days.

12.  The juvenile stage releases the cells of their symbiotic bacteria from
their intestines into the homoceol of the insect.
 The bacteria multiply in the insect homolymph and the infected host
usually dies within 24-48 hours.
 Once released, nematodes actively seek out the insect hosts. When a
host has been located, the nematodes penetrate into the insect
through body openings and release symbiotic bacteria that multiply
and rapidly kill the insect.
 Subsequently, nematodes feed upon the host , and mature into the
adults, which mate and produce the next generation.
 The life cycle is completed within a few weeks, and hundreds of
thousands of nematodes emerge in search of hosts.

14.  In laboratory tests, S. carpocapsae alone infected more than 250 species of
insects from over 75 families in 11 orders.
 Some nematode species may search for hosts at or near soil surface( e.g., S.
carpocapsae and S. scapterisci).
 Others are adapted to search deeper in the soil profile “ cruiser” ( e.g., H.
bacteriophora and S. glaseri).

15. Some appropriate nematode host targets are known:
 S. scapterisci against mole crickets;
 S. carpocapsae against cutworms and other mobile caterpillar pests;
 S. riobrave against cutworms and other noctuid larvae and pupae and citrus
weevils;
 S. feltiae against sawfly larvae and fungus gnat maggots; and
 H. bacteriophora against white grubs and other sedentary soil-dwelling
beetle larvae.

19.  Apply in the late evening. Nematodes are very sensitive to destruction
by bright sunlight and to desiccation if they are applied to plant foliage.
 Apply during the initial stage of pest damage.
 Light irrigation after application.
 Add adjuvants like glycerol, liquid paraffin.
 They can be applied with conventional chemical application equipment,
but screens in nozzles should be removed when applying nematodes
with a back-pack sprayer or spray rig.
 Nematodes should be reapplied on seven day intervals if damage
continues.
 Relative humidity should be high, ambient temperature should neither
be extremely hot or cold, soil temperature should be between 10 to 35
°C.

20. o High reproductive potential.
o Highly virulent( kill the host within 48 hours).
o Viable up to 3-6 months ( refrigerated at 10° C).
o Broad host range ( safe to vertebrates).
o Easy application using spray equipment's.
o Compatible with many chemical pesticides.
o Environmentally safe and acceptable.
o EPN seek out and kill all stages of harmful soil-dwelling insects.

21. o Nematode based insecticides- inactivated if stored in hot.
o Cannot left in spray tanks for long periods.
o Incompatible with many of the chemicals.
o Certain species cannot applied in high pressure equipment.
o Different species require different screen sizes.