Is the bumblebee (Bombus haemorrhoidalis) the only pollinator of large cardamom in central Himalayas, India?

Abstract

Amomum subulatum (Zingiberaceae) is one of the major cash crops of the Eastern Himalayas. Our earlier study had shown that Bombus haemorrhoidalis is the only pollinator of A. subulatum. This was surprising in light of findings that other members of Zingiberaceae have at least a few pollinators for each plant species. We hypothesized that A. subulatum also is a generalist. Studies were carried out in six plantations of Northeast India. Floral visitors and their frequency were recorded. The pollination efficiency of each visitor was determined on the basis of pollen transfer to the stigma following a single visit of the pollinator to virgin flower. B. haemorrhoidalis, Apis cerana, Megachile lanata, Episyrphus balteatus (hover fly), Macroglossum stellatarum (hawk moth), and Aethopyga siparaja (crimson sunbird) visited the flowers of A. subulatum. Of these, B. haemorrhoidalis, M. lanata, and A. siparaja were effective pollinators. B. haemorrhoidalis was an important pollinator across all the plantations. Flower opening pattern influenced the pollination efficiency of visitors.