Assemblage of flower visitors to Dillenia suffruticosa and possible negative effects of disturbances in Sarawak, Malaysia

Abstract

Dillenia suffruticosa (Dilleniaceae), a common pioneer shrub in Southeast Asia, is broadly distributed along roadsides. This species flowers throughout the year and is thought to be a keystone species for maintaining populations of flower visitors. To examine the flower visitors of this species, we conducted field surveys and described the behaviors of each flower visitor species within four different research sites: Primary Forests 1 and 2, Secondary Forest, and Mixed Vegetation. We caught 1087 individuals belonging to 51 species from 11 insect families and one species of arachnid. Most flower visitors belonged to Hymenoptera (98.6% of individuals); Trigona spp. and Xylocopa spp. (Apidae) accounted for 64.0% and 20.0%, respectively, of all caught individuals. According to observations of behavior by each species, effective pollinators may include Xylocopa spp. and Amegilla spp. (Apidae). We compared the research results among four research sites and found that the effective pollinators were not different among sites. However, the number of species and the abundances of flower visitors decreased in disturbed areas, especially in Secondary Forest. This research suggests the effects of human disturbances on the diversity and abundance of flower visitors.

Spatiotemporal Variability in the Reproductive Success of the Continually Flowering Shrub Dillenia suffruticosa in Borneo

“…A diverse assortment of visitors use this flower as a pollen resource, and Amegilla , Apis , Braunsapis , Diptera, Halictidae, Meliponini, and Xylocopa were observed visiting the flowers at the research sites (Tokumoto et al . ). Since D .…”

“…suffruticosa has concave stigmas and poricidal anthers, only visitors that perform buzz pollination and have sufficient body length to cover the pollination organs (stigmas and anthers) are efficient pollen vectors (Endress , Tokumoto et al . ). According to this characterization, we identified Amegilla borneensis (Cockerell, 1910), A. insularis (Smith, 1957), Xylocopa aestuans (Linnaeus, 1758), X. caerulea (Fabricius, 1804), X. shelfordi (Cameron, 1902), X. latipes (Druny, 1773), and X. dejeanii (Lepeletier, 1841) (Apidae) as pollinators of D .…”

“…suffruticosa based on our current and previous research (Tokumoto et al . ). Mature fruits are dehiscent and become mature and open about 30 d after flowering.…”

“…borneensis , A. insularis , X. aestuans , X. caerulea , X. shelfordi , X. latipes , and X. dejeanii ; Tokumoto et al . ) at each site during each study period.…”

“…, Tokumoto et al . ). Although Amegilla bees have not been reported to change their foraging behavior, Xylocopa alters its foraging behavior between GF and non‐GF periods (Appanah , Kato ), which may cause temporal fluctuations in the reproductive success of D. suffruticosa .…”