Diversity and Morphological Variation of Ambrosia Beetles from Forest Plantations in Western Sarawak
| dc.contributor.author | Erica Medina Binti Abdullah | |
| dc.date.accessioned | 2026-07-02T01:51:33Z | |
| dc.date.issued | 2026 | |
| dc.description | Ambrosia beetles are wood-boring insects (Coleoptera: Curculionidae) that play important ecological roles in ecosystems as pests, particularly in plantation areas. These beetles live in symbiosis with fungi, which can cause plant wilt and even mortality. In Sarawak, ambrosia beetles have been reported to infest exotic tree species such as Acacia mangium, A. crassicarpa, and Eucalyptus pellita in industrial forest plantations. However, despite reports of ambrosia beetle infestations in Sarawak, information on their species diversity and morphological variation remains limited, particularly across different plantation types. Consequently, baseline data linking ambrosia beetle diversity and morphology to monoculture and polyculture forest plantations in Sarawak are still lacking. Hence, this study aimed to investigate the diversity and morphological variation of ambrosia beetles in selected forest plantations in the western Sarawak. Fieldworks were conducted from January to October 2022 at two forest plantations, namely, License Planted Forest 42 (LPF42) in Sampadi, Lundu, and Sabal Forest Reserve (Sabal FR) in Simunjan. Adult ambrosia beetles were sampled using ethanol-baited intercept panel traps. Diversity indices and species assemblages were analysed using PAST software, while morphological variation was assessed through both qualitative and quantitative traits using multivariate ordination and statistical tests. A total of 170 ambrosia beetles were successfully collected, representing 11 species from the subfamily Scolytinae and three species from Platypodinae. LPF42 yielded seven species with 129 individuals, while 11 species comprising 41 individuals were recorded at Sabal FR. The Shannon-Wiener and Simpson’s indices were highest in Sabal FR (1.45 and 0.58, respectively), indicating greater species richness and evenness than LPF42 (0.50 and 0.28). Xylosandrus crassiusculus was the most dominant species, accounting for 82.94% of total captures. For the morphological assessment, five quantitative and 19 qualitative traits were analysed to evaluate inter- and intraspecific variation among ambrosia beetles. Quantitative analyses using Principal Component Analysis (PCA), Permutational Multivariate Analysis of Variance (PERMANOVA), Kruskal-Wallis (H), and Similarity Percentage Analysis (SIMPER) revealed that body length and pronotum width were the most important traits separating species, with Xyleborus ferrugineus distinguished by its larger body size. Qualitative analyses using Principal Coordinates of Analysis (PCoA), PERMANOVA, SIMPER, Chi-square (χ²) showed that elytral declivity and pronotal characters provided the strongest diagnostic value, reliably distinguishing species into discrete clusters. Xylosandrus crassiusculus exhibited marked morphological conservatism across sites, consistent with its global uniformity. Together, the integration of quantitative and qualitative approaches confirmed species-level boundaries and highlighted contrasting evolutionary strategies within Xyleborini. The findings provide baseline information on ambrosia beetle diversity and morphological variation in Sarawak, addressing a critical gap in regional entomological knowledge. This baseline contributes to future ecological studies and supports forest plantation monitoring and management efforts in Sarawak. Keywords: abundance, fungus-farming beetle, pest, weevil, Xylosandrus crassiusculus | |
| dc.identifier.uri | https://scholarhub.unimas.my/handle/123456789/1044 | |
| dc.language.iso | English | |
| dc.publisher | University Malaysia Sarawak | |
| dc.relation.ispartofseries | Faculty of Resource Science and Technology | |
| dc.subject | Science, Zoology, fungus-farming beetle, pest, weevil, Xylosandrus crassiusculus | |
| dc.title | Diversity and Morphological Variation of Ambrosia Beetles from Forest Plantations in Western Sarawak | |
| dc.type | Masters |