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Testing chemical defence based on pyrrolizidine alkaloids
1Departamento de Zoologia, Universidade Estadual de Campinas, Brazil
Animal Behaviour
|October 1, 1997
Summary
Pyrrolizidine alkaloids protect aposematic insects from predators. This study shows pileated finches learn to avoid prey containing monocrotaline, demonstrating alkaloids
Area of Science:
- Chemical Ecology
- Animal Behavior
- Evolutionary Biology
Background:
- Pyrrolizidine alkaloids (PAs) are key defenses in aposematic Lepidoptera.
- Evidence for PA protection against vertebrate predators is limited.
Purpose of the Study:
- To investigate the protective role of the PA monocrotaline against a vertebrate predator.
- To determine if learned avoidance of PAs is associated with visual cues.
Main Methods:
- Mealworms treated with monocrotaline were offered to pileated finches (Coryphospingus pileatus).
- Birds were then presented with prey bearing both monocrotaline and a blue stripe pattern.
- Finally, birds were offered blue-striped prey lacking monocrotaline to assess learned associations.
Main Results:
- Birds rejected monocrotaline-treated prey, indicating unpalatability.
- Birds learned to associate the blue stripe pattern with unpalatability, rejecting naive prey with this pattern.
- This demonstrates learned avoidance based on visual cues linked to chemical defense.
Conclusions:
- Monocrotaline provides a protective function against the vertebrate predator, the pileated finch.
- Learned associations between PAs and visual signals (aposematism) enhance predator deterrence.
- These findings support the role of PAs in the aposematic strategy of Lepidoptera.