Feeding II : Herbivorous Insects
Lecture Outline
• Importance of food selection
• Types of herbivores – diet breadth
• Specialization for plant feeding
Life history
Morphological
Sensory
• Finding food
• Termination of feeding - by the insect or by the plant?
• Question
Insects occur in association with every part of the plant kingdom
and constitute 26% of species from major taxa on earth
A feature of these interactions is their specialization, although
there are examples of polyphagy.
< 10% of herbivores feed on more than 3 different plant species.
Polyphagous - generalist
Oligophagous
Monophagous - specialist
Specialist: Feeding on a restricted number of plant species/families,
usually with specific adaptations for eating the tissues of these hosts.
Generalist: Feeding on a broad range of structurally and
chemically diverse plants. Adaptations for feeding on a range of
chemicals and tissue types.
Polyphagous insect herbivores
Insect species
Number of plant
species infested
Bemisia tabaci
506
Lygus lineolaris
385
Popillia japonica
295
How can you study ingestion if you can’t see it?
Electronic feeding monitors.
An insect is placed in an electrical circuit, and when it probes into a plant, the circuit is
completed (5 nA). As the insect probes, the various positions of the stylets, and the
behaviors cause changes in the electrical circuit and this can be recorded. Specific
waveforms correlate to specific events during the feeding process.
European and US
versions (DC vs. AC)
SUMMARY
• Herbivory is an ancient association
• There is a high degree of specialization, with some notable generalists
• Adaptations include life-history, morphology, physiology, and behavior
• Herbivore feeding behavior is influenced by plant architecture and chemistry
• Herbivore behavior can be manipulated to reduce crop damage