Dark axils and nodes in various plant species may serve as defensive mimicry of beetle and beetle faeces

Abstract

Anti-herbivory animal mimicry by plants has been paid scant attention, and as a result additional types are expected to be recognized. Lycium chinense plants growing in Japan have dark axils, and many leaf-eating beetles leave faeces on host plants or use their faeces as defence. The dark axils of Lycium chinense mimic poisonous faeces or faeces-covered larvae of the leaf beetle Lema decempunctata, which may result in reduced herbivory by mammalian and insect herbivores. Field work in the very different flora of Israel revealed that the same morphology/colouration exists in various wild plant species, both monocotyledons and dicotyledons. We therefore propose a new type of beetle and beetle faeces defensive plant mimicry, and suggest that this type of putative defensive mimicry against mammalian and insect herbivores is probably a widespread but overlooked phenomenon. Moreover, such mimicry may also attract visually oriented enemies that can attack various invertebrate herbivores that occupy these plants.

Keywords:

• defence
• faeces
• herbivory
• leaf beetles
• plant mimicry