Insect pollination of Aquilaria crassna (Thymelaeaceae): Effect of moths for the fruit setting in Thailand

The diversity and abundance of insect visitors to flowers of Aquilaria crassna were investigated in a natural forest in Khao Yai National Park and a plantation in Trat Province, Thailand. The behavior and pollinating effectiveness of the major insect visitors were also examined. Data were collected from 2006 to 2008 during the flowering season from March to May. A total of 103 insect species were found, representing 34 families from 4 orders. The highest number of species belonged to the order Lepidoptera (61 species), followed by Hymenoptera (26), and Coleoptera and Diptera (8). The efficiency of moth visitors was measured by the mean number of pollen grains found on the visitor's proboscis. Endotricha species (Pyralidae, Lepidoptera) were the most abundant and frequent visitors in both areas, and had pollen deposits of 16.29±5.36 (n=9) grains per proboscis. Fruit setting following different pollination treatments was not significantly different in the natural forest and the plantation, and no significant difference was found between hand pollination and open pollination. However, there was a significant difference in fruit setting between hand pollination and closed pollination, indicating that pollen transfer from anthers to stigma by vectors was required for fruit setting of A crassna flowers.