Flower-visiting insects of genus Melastoma (Myrtales: Melastomataceae) at the Fushan Botanical Garden, Taiwan

We investigated the diversity and behaviors of insects that visit flowers of four native species and a horticultural hybrid species of genus Melastoma (Family Melastomataceae) at the Fushan Botanical Garden in Taiwan biweekly from May to August 2020. Behaviors of flower-visiting insects were classified into eight categories and further assigned into four insect-flower interactions, namely pollination, herbivory, commensalism, and neutral. Our project provides baseline data of pollinator-plant interactions between the endangered M. intermedia and sympatric Melastoma species. Such information is useful in generating conservation and management actions as interspecific hybridization and genetic introgression has been reported from both wild and cultivated populations in this genus.

A total of 1,289 visits to flowers were recorded by at least 63 insect species belonging to seven orders. Number of insect species recorded per Melastoma species ranged from 9 to 39. Visiting, sonication, and passing were the three most frequently recorded behaviors, collectively accounting for 90.2% (n = 1,240) of the total observations. Pollination was the most dominant insect-flower interaction, accounting for 70.2% of the total observations, followed by neutral interaction (20.0%), herbivory (6.3%), and commensalism (3.5%). Sweat bees of genera Lasioglossum and Maculonomia (Hymenoptera: Family Halictidae) are considered key pollinators to Melastoma species in Fushan Botanical Garden based on their high number of visits and sonication behaviors. Our study represents the first comprehensive checklist of insects that visit the flowers of Melastoma species in Taiwan.