Extra floral nectar-secreting organs on Lima bean (Phaseolus lunatus) petiole. Extra florel nectar (EFN) is produced by a plant infested by spider mites (Tetranychus urticae).
This indirect chemical plant defence attracts natural enemies of spider mites and other herbivores.

Also volatile emissions of injured neighbouring plant induce EFN production in healthy plants. Atmospheric ozone can disturb this communication.
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