Prey composition and correlation between morphometry and prey biomass weight of the endemic Nepenthes bicalcarata in Kalimantan, Indonesia

Abstract

Abstract. Setiawan H, Hakim L, Fernandes AAR, Retnaningdyah C. 2022. Prey composition and correlation between morphometry and prey biomass weight of the endemic Nepenthes bicalcarata in Kalimantan, Indonesia. Biodiversitas 23: 5453-5460. Nepenthes bicalcarata Hook.f. is an endemic plant of the north-western part of Borneo, which is threatened by the conversion of its habitat. The understanding of the ecology of N. bicalcarata in regard to its prey is limited. This research aims to analyze the prey composition of N. bicalcarata and to investigate the correlation between pitcher morphometry and prey biomass weight. This research was done from November 2021 to March 2022 in a peat swamp primary forest in Sintang District, West Kalimantan Province, Indonesia. We used a quantitative descriptive approach and exploration method to gather data from N. bicalcarata in-situ habitat. The morphometry data of N. bicalcarata pitchers were collected in the field while the biomass trapped in N. bicalcarata pitcher liquid was sampled with a plastic bag and preserved with 70% of alcohol. Seven upper pitchers and 39 lower pitchers were recorded in this research. The composition of N. bicalcarata preys was dominated by Formicidae family including C. schmitzi, Polyrhachis sp. and Crematogaster sp.. Besides that, there were also mosquito larvae, ladybugs larvae, Ceratopogonidae larvae and some unidentified flying arthropods as the prey of N. bicalcarata. We found the plant’s parts in the lower pitchers of N. bicalcarata in the peat swamp forest, suggesting a possible mechanism of this plant to extract plant’s parts as alternative nutrient sources, yet this needs further research and intensive field observation. The correlation between pitcher volume and prey biomass weight was significant with P-value =0.00 (<0.01) and regression is formulated as Y (prey weight) = -0.1727 + 0.0039X (pitcher volume). This means that any increase in N. bicalcarata’s pitcher volume will increase the weight of the biomass linearly.