Diversity, Trophic Community Structures and Light Trapping Efficacy of Beetles in Western Sarawak, Borneo, Malaysia

Marcellinus Isaac Stia, Dominic (2022) Diversity, Trophic Community Structures and Light Trapping Efficacy of Beetles in Western Sarawak, Borneo, Malaysia. Masters thesis, UNIVERSITI MALAYSIA SARAWAK.

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Abstract

One of the significant representations of the world’s biodiversity is the beetle, representing about 40% of all known insects and these insect group can be found in all non-marine natural habitats. Currently, there are about 106 beetles’ families recorded from Borneo mainly from Sabah, but this number are not inclusive to all the families known to occur in Borneo and the values of beetle family numbers known to occur in Sarawak are uncertain, although included. In addition, the knowledge of trophic guild of beetles in Sarawak is also lacking. The current study attempted to examine efficacy of artificial light sources for light trapping methods used in monitoring beetle biodiversity because the knowledge is still limited especially in Sarawak. Firstly, the species diversity and abundance of beetle assemblages were investigated in western Sarawak, namely Gunung Gading National Park (GGNP), Real Living Lab, UNIMAS (RLL), Kampung Serpan Laut, Asajaya (MKSL) and Adis Buan Resort, Bau (HABR) by using modified Pennsylvanian light trap (MPLT), pitfall trapping (PFT) and hand-picking method (HPM). From an overall assemblage of beetles, a total of 1,198 specimens were successfully collected, representing 184 species from 32 different families. GGNP was represented with the most diverse species (H’= 3.449), followed by MKSL (H’= 3.163), HABR (H’= 3.032) and RLL (2.919) being the least diverse. The family Scarabaeidae represented as the most diverse and abundant family across all study sites, followed by family Chrysomelidae and Carabidae. Besides that, most beetles in Western Sarawak were herbivorous (N= 681, 59.06%), followed by predacious beetles (N=163, 14.14%), saprophagous beetles (N= 146, 12.66%), xylophagous beetles (N=111, 9.63%) and fungivorous beetles (N= 52, 4.51%) as the least common guild. The ecological interactions of beetle families in western Sarawak suggested that, in order to persist and coexist, more than half (59.06%) beetles adopted herbivory use of resources. Lastly, beetles were sampled vusing selected artificial light sources, namely mercury vapour lamp (MVL), blacklight ultraviolet tubes (UVL) and compact fluorescent lamp (CFL) by which all three light sources were tested for efficacy assessments in the same forest of Adis Buan Resort, Bau. From the efficacy assessment, UVL as the artificial light source used in MPLT for beetle biodiversity monitoring and its benefit by aspect of energy saving, greater localised illumination and a higher capture rate, suggested that this light source a good candidate for this cause. In conclusion, since this study are only limited to Western Sarawak and the overall study of beetles in Sarawak is still in insipient stages, more intensive and continuous prolonged studies are needed especially in other parts of Sarawak to enhance further understanding of the beetle biodiversity in this hotspot area.

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