PARENT SESSION
Poster Session #4: Herbivory.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Preferences and patterns of damage of the insect borer Oncideres albomarginata on the dioecious tropical tree, Spondias purpurea .

Uribe-Mú, Claudia^*,1, Quesada, Mauricio¹, ¹ Instituto de Ecologia, UNAM, Morelia, Michoacan, MEXICO

ABSTRACT- Evidence from the literature has shown that herbivores prefer to feed more on male than on female plants in dioecious species. Most of these studies have demonstrated this pattern of herbivory on leaf tissue but few have evaluated preferences and patterns of other types of insect damage on dioecious plants. Insect borers are known to girdle or remove whole branches from plants with unknown consequences to their growth and reproduction. The objective of our study was to determine preferences and patterns of damage caused by the insect borer Oncideres albomarginata on the tropical tree Spondias purpurea, and the consequences of this damage on the reproduction of this tree. The study was conducted in the tropical dry forest of the Chamela-Cuixmala Biosphere Reserve, Mexico. Our results indicate that O. albomarginata selectively cuts and ovoposits reproductive branches of an average of 20 mm in diameter. During 3 consecutive years of study, O. albomarginata preferred to cut and ovoposit branches of female trees, even though male trees produced significantly more branches that could be potentially used by the insect. The average percentage of branches damaged per individual was 12% for female trees and 6% for male trees. O. albomarginata preferred to cut the branches of female trees prior to reproduction of S. purpurea, possibly due to a higher accumulation of non-structural carbohydrates during this period. The average biomass of branches of 20 mm in diameter, measured as dry weight, of female trees was significantly greater than that of male trees. Damaged branches of S. purpurea compensated for the production of fruit a year after damage occurred.

KEY WORDS: herbivory, insect borer, Tropical dry forest, plant reproductive success