Pollination and seed dispersal of Aquilaria sinensis (Lour.) Gilg (Thymelaeaceae): An economic plant species with extremely small populations in China

Abstract

Pollination and seed dispersal in angiosperms have long been investigated in order to understand the coevolution of plants and animals. However, the signals from flowers and/or seeds to attract pollinators and/or seed dispersers have received comparatively little attention. In this study, the pollination biology and seed dispersal of the vulnerable agarwood plant Aquilaria sinensis (Lour.) Gilg, a traditional medicinal plant in China, was studied in its natural distribution range. The reproductive tactics of A. sinensis were studied in detail by employing various tests dealing with fruit set and also seed dispersal. Dynamic headspace extraction followed by GC-MS analysis was also performed in order to reveal the composition of floral scent. The results showed that noctuids and pyralids are the most effective pollinators of pollinator-dependent A. sinensis. The main compounds of the floral scent were (E, E)-α-Farnesene (61.9 ± 3.2%), trans-Ocimene (16.6 ± 1.2%), and Benzyl salicylate (4.6 ± 1.1%). The results obtained from seed dispersal experiments indicate that hornets are effective seed dispersers and they may play an important role in long-distance seed dispersal of A. sinensis. Based on our findings, we recommend several protection methods for this threatened agarwood plant in China.

Keywords: Aquilaria; GC–MS; Pollination; Pyralidae; Seed dispersal; Vespa.

Fig. 1

Plantation, pest, pollination and seed dispersal of A. sinensis. Plantation of A. sinensis at JC location (a); larvae and imago of Heortia vitessoides, an obligate pest of A. sinensis (b) and (c); three moth pollinators of A. sinensis (d–f); hornets attack diaspores of A. sinensis (g) and (h); discarded diaspores with partly eaten (left) and intact (right) elaiosomes of A. sinensis (i). Photos taken by G Chen (a, b, c, e), Chang-Qiu Liu (d and f) and Meng Guo (g–i).