Plant coloration undermines herbivorous insect camouflage

Abstract

The main point of our hypothesis "coloration undermines camouflage" is that many color patterns in plants undermine the camouflage of invertebrate herbivores, especially insects, thus exposing them to predation and causing them to avoid plant organs with unsuitable coloration, to the benefit of the plants. This is a common case of "the enemy of my enemy is my friend" and a visual parallel of the chemical signals that plants emit to call wasps when attacked by caterpillars. Moreover, this is also a common natural version of the well-known case of industrial melanism, which illustrates the great importance of plant-based camouflage for herbivorous insects and can serve as an independent test for our hypothesis. We claim that the enormous variations in coloration of leaves, petioles and stems as well as of flowers and fruits undermine the camouflage of invertebrate herbivores, especially insects. We assume that the same principle might operate in certain animal-parasite interactions. Our hypothesis, however, does not contrast or exclude other previous or future explanations of specific types of plant coloration. Traits such as coloration that have more than one type of benefit may be selected for by several agents and evolve more rapidly than ones with a single type of advantage.

Cryptic coloration of Macaranga bancana seedlings: A unique strategy for a pioneer species

“…There is a scarcity of examples of such visual defenses from the tropics. They include being red/brown to look dead, 7 delayed greening, 8 red leaf undersides that defend from fungal attacks, 9 different adaxial and abaxial leaf colors that undermine herbivorous insect camouflage 10 and aposematism. 11 Macaranga bancana (Miq.)…”

Unripe red fruits may be aposematic

“…The spiny unripe red fruits of Emex spinosa and Hedysarum spinosissimum are also unpalatable for large mammalian herbivores and need no advertisement to attract frugivores protection by anthocyanins from photoinhibition and photooxidation. 33,[110][111][112] Gould et al 110 Lev-Yadun et al 113,114 LevYadun, 46,47 Lev-Yadun and Gould 36,37 and Archetti et al 38 have already argued that the non-photosynthetic plant pigments have the potential to serve more than one function concurrently. Thus, various hypotheses concerning coloration of fruits need not contrast or exclude any other functional explanation.…”

Lipid Biosynthesis and Protein Concentration Respond Uniquely to Phosphate Supply during Leaf Development in Highly Phosphorus-Efficient Hakea prostrata

“…These may compensate for low levels of photosynthetic pigments and protect these leaves against photodamage and reactive oxygen species (Lee and Collins, 2001;Hatier and Gould, 2008) as well as provide protection against herbivory (Lev-Yadun et al, 2004). The pigment distribution in H. prostrata leaves is very different from that found in Arabidopsis, where anthocyanins accumulate in older leaves (Diaz et al, 2006) and chloroplast development takes place early during leaf development (Breeze et al, 2011), with high chlorophyll and Rubisco concentrations in young and expanding leaves.…”