J. Bio. & Env. Sci. 2016 204 | Suhaila et al. RESEARCH PAPER OPEN ACCESS Role of Ephemeroptera, Plecoptera and Trichoptera (Insecta) functional feeding groups in leaf decomposition in Tropical River Suhaila Ab. Hamid 1 , Mohd Fakhrullah Salafusalam Mohd Affendi *1 , Nur Aida Hashim 2 1 School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia 2 School of Food Science and Technology, Universiti Malaysia Terengganu, Kuala Terengganu, Malaysia Article published on July 22, 2016 Key words: Leaf packs, Decompose, Functional feeding groups, EPT, Tropical river, Dipterocarp forest. Abstract The riparian vegetation along the riverbanks had an influence on Ephemeroptera, Plecoptera and Trichoptera (EPT) functional feeding groups’ composition (FFG). This is because FFG from these three orders play a major role in leaf decomposition. A study of EPT FFG on leaf breakdown was carried out on two types of leaf packs, single leaf species (Pometia pinnata) and two leaf species (Pometia pinnata and Dolichandrone spathacea) in Tupah River, Kedah, Malaysia. In single species leaf pack, the collector-gatherers were most abundant but in two species leaf pack, the collector-filterers were more abundant. Shredders were well represented in the two species leaf pack while predator abundance was higher in the single species leaf pack. On the first 14 days of leaf immersion, the shredders were found to be the most highest in abundance. Meanwhile, high abundance of collector-filterers and collector-gatherers were observed at the later stage of decomposition (14-21 days) in both leaf types. However, higher predator populations were recorded on day 14 until day 28 corresponded to high availability of prey species (collectors) within the leaf packs. * Corresponding Author: Suhaila Ab Hamid  ahsuhaila@usm.my Journal of Biodiversity and Environmental Sciences (JBES) ISSN: 2220-6663 (Print) 2222-3045 (Online) Vol. 9, No. 1, p. 204-213, 2016 http://www.innspub.net