Diverging patterns of host use by phytophagous insects in relation to leaf pubescence in Arbutus xalapensis (Ericaceae).

Foliar pubescence in the mexican madrone (Arbutus xalapensis H.B.K.) is an extremely variable character. Leaf specimens of pilose and glabrous madrones showed a similar composition of major secondary compounds. On the other hand, sympatric pilose and glabrous individuals were found to support significantly different insect guilds. Insect preference was strongly associated to mouthpart anatomy. Chewing and gall-forming insects were significantly more abundant on glabrous trees while sucking insects were more common on pilose trees. Additionally, parasitation of sucking insects was lower on pilose trees, possibly because the plant trichomes provide protection against parasitoids.