Herbivore damage and leaf loss in the New Zealand pepper tree ('Kawakawa'; Macropiper excelsum; Piperaceae)

Abstract

The pattern of herbivore damage on the New Zealand pepper tree (kawakawa; Macropiper excelsum) caused by its main insect herbivore (Cleora scriptaria) was investigated in the field and laboratory. In the field, only a small proportion of kawakawa leaves had no herbivore damage and C. scriptaria typically produced a number of small holes in each leaf. Leaves were shed at a rapid rate but leaf shedding was not increased by higher levels of herbivore damage. Some older leaves had less damage than would be expected for their age, possibly suggesting some variation in leaf susceptibility to herbivory. The effect of previous leaf damage on subsequent herbivory was examined in the field and laboratory. On no occasion did artificial leaf damage, or herbivory by larvae of the same or another species, affect the edibility of leaves to C. scriptaria. The results suggest that leaf shedding by kawakawa was not primarily a response to herbivore damage and induced defences against herbivores could not be demonstrated in this system.