intensity and time of exposure and the nature of the
stimulus [128].
l
Foraging strategies differ from species to species.
2 Foraging Strategies
2.1 Ambush
Foraging Strategy
Ambushing EPNs remain at one place or close to the soil surface
and detect host insects by direct contact. They are attracted toward
CO 2 and host-specific odorants, whereas volatiles find no major
role in host-finding. Ambushers successfully manage insect pests
which are extremely mobile at the surface of the soil like cutworms,
armyworms, and mole crickets. Ambusher EPN species include
S. carpocapsae and S. scapterisici.
2.1.1 Standing Behavior
An infective juvenile of ambusher attaches to the mobile hosts at
the soil surface by raising the anterior portion of its body and waves
it back and forth and balances on its tail, referred to as “standing”
[129], “nictation” [130], and “winken” (Fig. 1) [131].
2.1.2 Jumping Behavior
IJs of ambushers also exhibit jumping behavior, where the IJ stands
on its tail, curls, and propels itself into the air to attach to the
hosts [132].
2.2 Cruise Foraging
Strategy
Cruising EPNs actively move about through the soil to find their
host by detecting carbon dioxide or volatiles emitted by the host.
Cruisers efficiently monitor sedentary and slow-moving insect pests
at different soil depths, such as white grubs and root weevils.
Cruiser EPN species include H. bacteriophora and S. glaseri.
2.2.1 Crawling Behavior
IJs of cruisers crawl by sinusoidal movement on the substrate using
the surface tension forces to propel them forward or backward to
locate their hosts [133].
2.3 Intermediate
Foraging Strategy
Intermediating EPNs use both ambushing and cruising strategies
to locate their host. These foragers are less successful when compared to ambushers and cruisers at parasitizing hosts either on the
soil surface or deep in the soil profile. Intermediate EPN species
include S. feltiae and S. riobrave.
3 Foraging Assays
3.1 Standing
and Jumping Behavior
1. Sprinkle 0.5 g of sand particles on a 9-cm petri dish surface,
lined with double-moisten filter paper.
2. Apply 100 IJs on the filter paper surface.
28
Nematode Behavior
stimulus [128].
l
Foraging strategies differ from species to species.
2 Foraging Strategies
2.1 Ambush
Foraging Strategy
Ambushing EPNs remain at one place or close to the soil surface
and detect host insects by direct contact. They are attracted toward
CO 2 and host-specific odorants, whereas volatiles find no major
role in host-finding. Ambushers successfully manage insect pests
which are extremely mobile at the surface of the soil like cutworms,
armyworms, and mole crickets. Ambusher EPN species include
S. carpocapsae and S. scapterisici.
2.1.1 Standing Behavior
An infective juvenile of ambusher attaches to the mobile hosts at
the soil surface by raising the anterior portion of its body and waves
it back and forth and balances on its tail, referred to as “standing”
[129], “nictation” [130], and “winken” (Fig. 1) [131].
2.1.2 Jumping Behavior
IJs of ambushers also exhibit jumping behavior, where the IJ stands
on its tail, curls, and propels itself into the air to attach to the
hosts [132].
2.2 Cruise Foraging
Strategy
Cruising EPNs actively move about through the soil to find their
host by detecting carbon dioxide or volatiles emitted by the host.
Cruisers efficiently monitor sedentary and slow-moving insect pests
at different soil depths, such as white grubs and root weevils.
Cruiser EPN species include H. bacteriophora and S. glaseri.
2.2.1 Crawling Behavior
IJs of cruisers crawl by sinusoidal movement on the substrate using
the surface tension forces to propel them forward or backward to
locate their hosts [133].
2.3 Intermediate
Foraging Strategy
Intermediating EPNs use both ambushing and cruising strategies
to locate their host. These foragers are less successful when compared to ambushers and cruisers at parasitizing hosts either on the
soil surface or deep in the soil profile. Intermediate EPN species
include S. feltiae and S. riobrave.
3 Foraging Assays
3.1 Standing
and Jumping Behavior
1. Sprinkle 0.5 g of sand particles on a 9-cm petri dish surface,
lined with double-moisten filter paper.
2. Apply 100 IJs on the filter paper surface.
28
Nematode Behavior