Muhammad Faisal Riaz 24

Nimra Altaf

Faizan Iqbal

Faiz ullah Faiz 04

Muhammad Zeeshan Nazar 01

Jafar Ali Naqi Khan

Case Study

Learning in the Parasitoid Wasp(Hyssopus pallidus)

Before discuss this case study We should know,

A parasitoid’s host-searching ability depends on,

i. Responses to chemical cues.

ii. These responses have both genetic and learned components.

Any critical phase at which a parasitoid is more likely to learned?

Does learning carry through from one life stage to another?

?Questions arise in this topic are

Cydia pomonella is the major pest of apple fruits.

Hatched parasitoid larvae disperse

throughout the orchard to find new host.

Hyssopus pallidus (parasitoid) used as biocontrol.

Q. Either wasp depends on the traces of (Moth’s)

frass

in the channels of infested fruit or not???Moth’s caterpillar feed on

Artificial diet

Strong decline of the response to frass of moths thatfed on artificial diet while other group showed opposite result.

Apple cues

• Host derived frass were recognized innately • But learning was required before wasp recognized fruit derived

components.

Q. Did parasitoid need to learn fruit related chemicals from caterpillars and their feces or exposure to fruit itself was sufficient?

After perceiving the existence of learning behavior, the question arise

Moth Caterpillars(1st instar moth)

AppleFeed Extract WormWaited for

5th instar

Worm

Filter paper with extract

Apple pieceAppleExtract

Feed on wheat germ

Introduced mated female in each group

New cage withoutapple cues

NewGeneration

New Generation4 days old

Filter paper on top treating with apple extract

Hyssopus larva fed with apple diet showed significantly greater response to host frass than reared without apple cues.

Q. Did a high response to host frass require exposure to both the taste and smell of apple?

Apple supplement Odor of apple extract

Both treatments enhanced female response but their response towards olfaction was more effective as taste and smell together.

Parasitoids reared on

caterpillars

Parasitoids reared on

caterpillars

Q. Was their a sensitive stage in parasitoid’s life history

for learning the relevant stimuli?

Wasps exposed to apple clues at different developmental stags.

Never exposed to apple at all

Group 1 Showed greater response as adult to natural frass.

Exposed to apple throughout its life

Group 1 Group 2

Stage exposed to odourof apple fruit extract Adult response to frass extract from apple-fed host caterpillars

Total development

Egg-young larva

Old larva-pupa

Pupa emergence

Adult

No Exposure (Control) (0)

0 5 10 15 20 20 40 60 80 100 120 140 160 180Response(s) Days from oviposition

Parasitoids are more responsive to the

control than menthol

Control Group Parasitoid used

only solvent

Egg to Larvae

Experimental Group Parasitoid

used Menthol

Q. Was pre-imaginal learning confined to fruit cues,or was it a more general phenomenon?

Parasitic wasp Hyssopus pallidus learns to locate its hidden

host by its frass and this recognition is two stage process.

Host-derived chemicals in frass innately.

Apple derived chemicals learned only through exposure in

early life cycle;

not early adulthood, but from egg to larva

Conclusio

n