The Effect of a Consumer, Phytomyza ilicis, on Seasonal Leaf-Fall in the Holly, Ilex Aquifolium

Abstract

The leaf-mining larvae of a fly, P. ilicis, cause premature and unseasonal leaf-fall in the holly, I. aquifolium. Holly trees are phenotypically variable in the structure and texture of their leaves and P. ilicis causes a greater seasonal distortion of leaf-fall in some trees than in others. Holly trees probably regulate the frequency of mined leaves by shedding them prematurely while P. ilicis is still in the larval stage. Another possibility is that by spreading out the season of leaf-fall, P. ilicis is beneficial to the trees. Year-round leaf-fall should lead to a more even release of nutrients back to the tree than would occur if there were no leaf-miners present.