INTERESTING FACT ABOUT INSECT FEEDING.....

1. INSECTS & THEIR FEEDING…
• Insects feed very specifically on their host.
• They recognize their host through
morphological, phenological, and chemical
traits.

2. PHYTOPHAGOUS INSECT
vs.
DIVERSITY
• The phytophagous insects undergo dramatic
changes and they tend to be more diversified
than their non-phytophagous sisters.
• The most likely driver is that they diversify
through host shifts followed by evolution of
new species.

3. USE OF PLANT TRAIT SPACE
DURING HAD-
THE GAPE & PINCH MODEL

4. INSECT- HOST PLANT
• All plant species vary intra specifically for
numerous morphological, phenological, and
chemical traits.
• This variation defines a set of phenotypes that
are available for attack by a phytophagous
insect searching its environment for suitable
hosts.

5. INSECT FEEDING - PATTERN
• The total area available for a specific insect to
feed on is its “available trait space”.
• The area or rather the plants on which an
insect has fed is called its “attacked trait
space”.

6. Continued…
• The relationship between available and
attacked trait spaces will depend upon the
preference, performance of the insect.
• The “attacked trait space” either represents
the common preference of hosts by the
insects or the sum total of the distinct
preferences of host by different insects.

7. POSSIBILITIES OF INSECT FEEDING

8. STAGES IN EVOLUTION
OF NEW SPECIES

9. • STAGE 1:Single-Host Specialists and the Importance
of host choice errors:
Host shift occurs when a few insect individuals
start attacking the ‘wrong’(novel) plants.
ADJACENT ERROR HYPOTHESIS.

10. • STAGE 2: Oligophagous Feeding Following Diet
Expansion:
• “ADJACENT OLIGOPHAGY HYPOTHESIS.”

12. • STAGE 3:Nascent Host-Specialist Forms and the
Selection- Gene Flow Tension.
• “TRAIT DISTANCE- DIVERGENGE HYPOTHESIS”
separation of attacked trait spaces
occur

13. INTERNATIONAL JOURNAL OF ECOLOGY

14. • STAGE 4:Pair of Established Host Specialists:
Reproductive isolation
Ecological speciation
• “DISTANCE RELAXATION HYPOTHESIS”

15. INTERNATIONAL JOURNAL OF ECOLOGY

16. GAPE & PINCH MODEL-
NOMENCLATURE
• The overall conceptual model suggests a pair of
attacked trait spaces that begin close together, move
apart, and then move back together like pincers.
• This movement underlies the terminology “gape-
and-pinch” model of trait-space use.

17. REFERENCES…
• RESEARCH ARTICLE: Use of Host-Plant Trait Space by
Phytophagous Insects during Host-Associated
Differentiation: The Gape-and-Pinch Model, Stephen
B. Heard, Hindawi Publishing Corporation,
International Journal of Ecology,Volume 2012,
Article ID 192345, 15 pages
doi:10.1155/2012/192345.
• www.wikipedia.com
• Host-Plant Selection by Phytophagous Insects By
Elizabeth A. Bernays, Reginald F. Chapman