Effects of different pollinators and herbivores on the fruit set height of the mammal-pollinated tree-climbing vine Mucuna macrocarpa

Abstract

ABSTRACT Although different flower-visiting frequencies and behaviors are known to cause differences in fruit set rates, the effects of different pollinators on the fruit set position are unclear. The climbing vine Mucuna macrocarpa (Fabaceae) needs mammalian pollinators for fruit set. This species is widely distributed in Asia and is pollinated by different mammals in different regions. This study assessed the effects of different pollinators, including their ability to fly, and of herbivores on the fruit set height of M. macrocarpa. The heights of inflorescences and fruits were measured in Kyushu, Okinawa-jima Island (Okinawa), Taiwan, and Thailand. Flying mammalian pollinator (bat) activity was recorded in Okinawa, and non-flying mammalian pollinator activity was recorded in the other three regions. The flowers were observed from the ground to canopy levels in all regions; no fruits were observed at the ground level on Okinawa, whereas fruits were observed from the ground to the canopy levels in Kyushu, Taiwan, and Thailand. In Kyushu, however, fruits were less frequently observed at the ground level. Although pollinators visited flowers located near the ground level, camera traps frequently recorded sika deer (Cervus nippon) feeding on the flowers and fruits near the ground level. Our data show that both the flying ability of pollinators and the density of large-sized herbivores affect the fruit set position.