2.4 Larval
Performance Analysis
A no‐choice feeding bioassay can be directed for ascertaining the
impact of plant disclosure toward EPN cues on performance of the
herbivore.
1. Relate the larval mass increase and foliage feeding in exposed
plants to cues from EPN carcass, control carcass, or empty sand
controls.
2. Cage five neonates on undamaged foliage succeeding the initial
exposure.
3. Examine the larvae each day and if the larvae had fed on more
than half of the leaf tissue in the cage, then transfer to fresh
leaves.
4. Take out larvae after 5 days and weigh.
5. Scan the leaves of individual plant and calculate the total leaf
area fed by larvae with Adobe Photoshop software.
2.5 Insect Herbivore
Oviposition Preference
Analysis
To assess the effect of EPN chemical cues on herbivore oviposition,
a three‐way choice test is piloted with female insect.
1. Place a single insect in a cage consisting of three separately
planted potato plants.
2. Use soil as control, and place a pot with three EPN‐infected
cadavers (G. mellonella with IJs) and another pot with three
control cadavers (G. mellonella).
3. Place female insect in the middle of the pot and allow to
oviposit for 3 days.
4. Count the total number of eggs in each treatment.
3 Volatile Cues
Entomopathogenic nematodes are attracted to volatile substances
released by insect-damaged plants. These volatile compounds work
as a kind of chemical signals (semiochemical). By appealing EPNs to
an affected plant, the volatile compound provides indirect fortification to the plant. The exposure period of an EPN to volatile
compounds is of crucial significance for recognizing chemical stimuli. EPN reaction to diverse volatile cues is a species-specific
feature [143].
3.1 Detection of
Volatiles Emitted by
Insect Larval Hosts
To examine the influence of odors on host-locating behaviors, use
thermal desorption-gas chromatography-mass spectroscopy
(TD-GC-MS) to recognize insect emanated odorants.
3.1.1 Materials Required
l
Flask.
l
Last-instar larvae of Galleria mellonella / Tenebrio molitor.
l
Thermal desorption tube.
36
Chemical Ecology
Performance Analysis
A no‐choice feeding bioassay can be directed for ascertaining the
impact of plant disclosure toward EPN cues on performance of the
herbivore.
1. Relate the larval mass increase and foliage feeding in exposed
plants to cues from EPN carcass, control carcass, or empty sand
controls.
2. Cage five neonates on undamaged foliage succeeding the initial
exposure.
3. Examine the larvae each day and if the larvae had fed on more
than half of the leaf tissue in the cage, then transfer to fresh
leaves.
4. Take out larvae after 5 days and weigh.
5. Scan the leaves of individual plant and calculate the total leaf
area fed by larvae with Adobe Photoshop software.
2.5 Insect Herbivore
Oviposition Preference
Analysis
To assess the effect of EPN chemical cues on herbivore oviposition,
a three‐way choice test is piloted with female insect.
1. Place a single insect in a cage consisting of three separately
planted potato plants.
2. Use soil as control, and place a pot with three EPN‐infected
cadavers (G. mellonella with IJs) and another pot with three
control cadavers (G. mellonella).
3. Place female insect in the middle of the pot and allow to
oviposit for 3 days.
4. Count the total number of eggs in each treatment.
3 Volatile Cues
Entomopathogenic nematodes are attracted to volatile substances
released by insect-damaged plants. These volatile compounds work
as a kind of chemical signals (semiochemical). By appealing EPNs to
an affected plant, the volatile compound provides indirect fortification to the plant. The exposure period of an EPN to volatile
compounds is of crucial significance for recognizing chemical stimuli. EPN reaction to diverse volatile cues is a species-specific
feature [143].
3.1 Detection of
Volatiles Emitted by
Insect Larval Hosts
To examine the influence of odors on host-locating behaviors, use
thermal desorption-gas chromatography-mass spectroscopy
(TD-GC-MS) to recognize insect emanated odorants.
3.1.1 Materials Required
l
Flask.
l
Last-instar larvae of Galleria mellonella / Tenebrio molitor.
l
Thermal desorption tube.
36
Chemical Ecology