An assemblage of beetle specimens from family Carabidae (ground beetles) was carried out at Kenyir water catchment as an indicator to measure disturbance. The samplings were conducted from 30th July to 1st August 2007 at limestone forest of Teluk Bewah and the dipterocarp forest of Sungai Cicir. 28 individuals from 13 species were collected from Teluk Bewah whereas 54 individuals from ten species was sampled from Sungai Cicir. The carabids were more specious (Simpson Diversity index: 0.97) and more abundant (Margalef index: 5.35) at Teluk Bewah compared to Sungai Cicir (Simpson Diversity index, 0.72: Margalef index, 2.22). Light trapping was most efficient assembling 97.56% of ground beetles compared to Malaise trap, pitfall and net sweeping. This is the first record of beetle assemblage at Kenyir water catchment, Malaysia. New records for Kenyir, Terengganu, Malaysia are Abacetus sp. 1, Abacetus sp. 2, Acupalpus rectifrotis, Aephnidius adelioides, Dischissus notulatus, Dolichoctis sp., Dolichoctis sp. 2, Dolichoctis straitus, Ophinoea bimaculata, Perigona sp., Pheropsophus piciccollis, Pheropsophus occipitalis, Stenolophus quinquepustulatus, Stenolophus smaragdulus, Stenolophus sp., Tachys coracinus, Casnoidea sp., Orthogonius sp. Seven species coded as Cara C, Cara J, Cara M, Cara N, Cara O, Cara R and Cara S were unidentified and are probably new species to be described in another report. There is moderately high diversity (Simpson Diversity index: 0.846) of Carabidae indicating that ecotourism does not affect diversity of ground beetle at Kenyir Lake.
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Carabidae (Ground beetle) is the third largest family of beetles after Staphylinidae and Curculionidae in United States of America. The carabid beetles varies in size, shape and color. Most species are dark, shiny and flattened, with striate elytra. Ground beetles are commonly found under stones, logs, leaves, bark or debris or running about the ground.
Ground beetles represent a large and diverse group of arthropods. More than 40,000 species of Carabidae have been described. They are the largest family of Adephagan beetles (Kromp, 1999) whose habitats range from caves to rainforest canopy and alpine. Most carabids are polyphagous, with insect prey predominating, but plant matter also being ingested (Kromp, 1999).
Because of their ubiquity and the availability of good taxonomic keys, ground beetles have been studied as potential indicators of the effects of a wide variety of management practices, including general land use (Larsen et al., 2003).
Carabid populations are sensitive to anthropogenic changes in habitat quality and are considered to have bioindicative value for assessments of environmental pollution, habitat classification for nature protection or land use (Descender et al., 1994). Common interest in ground beetles stems from a desire to use them as ecological indicators (Rainio and Niemela, 2003).
Kenyir lake is the largest man made lake in Southeast Asia located in the state of Terengganu, Malaysia. The lake comprises of 340 islands, which were once hilltops and highlands. It has more than 14 waterfalls, rapids, rivers, limestone caves and tropical rain forests. There are more than 8000 species of flowers, 2500 species of plants and trees and 300 species of fungus, 800 butterflies, 370 species of orchids, 1000 species of birds and 200 species of other animals, 300 species of freshwater fish dwelling in the lake. Department of Fisheries reported that species such as big Lampan Sungai (Barboides), Kelah (Malaysian Mahsee), Toman (Snakehead), Kawan (Friendly Barb), Kalui (Giant Gouramy) and Kelisa (Green Arowana) are found in waters and around the dead trees.
The exotic wildlife rich with numerous types of flora and fauna leads to endless discoveries and adventures attracts many ecotourists, fisherman and others.
This study was conducted on ground beetle at Kenyir water catchment, in order to investigate whether increasing magnitude or severity of human disturbance due to tourist activities have decline the abundance, species richness and/or species diversity of Carabidae.
MATERIALS AND METHODS
Study sites: Sampling was conducted on July 30th 2007 until August 1st 2007 at two different sites in Kenyir water catchment (5°11" N, 102°48" E). The Water Catchment Area is 103 ha. First sampling site was at Teluk Bewah which is a limestone forest and the second sampling site was Sungai Cicir which is dipterocarp forest (Fig. 1).
Beetle collection: Eight light traps, four malaise traps and forty pitfall traps were set up at Teluk Bewah and Sungai Cicir. While setting up the traps a sweep net was used on the bushes in the study area to catch the carabid beetles manually.
Pitfall traps: The pitfall trap is made up of a plastic jar with 6.0 cm diameter and total volume of 250 mL. A hole in the ground was dug to place each jar in it. Each jar was filled up to half with 70% alcohol. Two twigs were buried at both sides of the hole and dried leaf was placed on the twigs thus preventing the effect of rainfall. Five pitfall was placed in a 1x1 m quadrat with the fifth pitfall placed in the center of the quadrat (Fig. 2). The traps were left in the field for 24 h before collection. The alcohol was poured into a plastic bag containing a label made by pencil and brought back for further processing at the wet laboratory at Teluk Bewah Basecamp.
Malaise trap: The malaise trap is made up of black nylon netting (Fig. 3). A collection jar (C) positioned at the topmost end of the trap was half filled with 70% ethyl alcohol. The sweet smell of the alcohol attracted the carabid beetles to fly towards it thus entering the jar and got caught in it. The alcohol also preserved the caught beetle.
|Fig. 1:||Location of study sites at Kenyir water catchment|
|Fig. 2:||A diagrammatic presentation of five Pitfall traps set up at each location|
|Fig. 3:||A Malaise trap set up 1 m from the ground|
|Fig. 4:||Light trap was set up for 4 h at 1900 h|
Night sampling using light trap: Light trapping is made up of white mosquito netting. The 160 watt mercury bulb was powered by a Honda generator providing light to the light trap (Fig. 4). Carabid beetle attracted to light will be caught at the net. Manually using hand, pill bottle or aspirator the carabid will be collected, put in killing jar which has been poured with ethyl acetate.
Sorting and preservation: The carabid beetles were sorted to morpho species and preserved in 70% alcohol and put in scintillation vials for easy transportation to University Malaya for further study. Each vial was sealed with parafilm.
Identification of Beetle: The specimens were brought back to University of Malaya, pinned and dried in the oven before being identified. Abundance and diversity of species were determined using Margalef index and Simpson diversity index.
Carabid assemblage at Kenyir revealed 29 species from 82 individuals. Nineteen species of Carabidae were caught from Teluk Bewah and ten species of Carabidae were caught from Sungai Cicir. List all identified beetle species are shown in Table 1-3. Example of identified species collected at Kenyir Lake is given by Fig. 6-8.
Seven species unidentified species are given code name Cara C, Cara J, Cara M, Cara N, Cara O, Cara R and Cara S.
Figure 5 shows that there is a higher abundance of carabid beetle at Teluk Bewah (Margalef index: 5.35) compare d to Sungai Cicir (Margalef index, 2.22). Similarly, ground beetles at Sungai Cicir ( Simpson diversity index: 0.72) is less diverse and less specious compared to Teluk Bewah (Simpson Diversity index: 0.97)
|Fig. 5:||The index diversity of carabid beetle at different sites|
|Table 1:||Ground beetles collected at Teluk Bewah on 30th July 2007|
|SN: Sweep net, MT: Malaise trap, PF: Pitfall, LT: Light trap, -: No catch|
|Table 2:||Ground beetles collected at Sungai Cicir on 1st August 2007|
|SN: Sweep net, MT: Malaise trap, PF: Pitfall, LT: Light trap, - :No specimen|
|Table 3:||List of Ground beetles collected at Tasik Kenyir|
|SN: Sweep net, MT: Malaise trap, PF: Pitfall, LT: Light trap, -: No specimen|
|Fig. 6:||Aephnidius adelioides (5.261 mm)|
|Fig. 7:||Asupalpus rectifrotis (3.460 mm)|
|Fig. 8:||Casnoidea sp. (2.394 mm)|
From the total number of Coleoptera (beetles) assembled at Lake Kenyir, Carabids (13.5%) was the third most collected after Staphylinid beetles (16.8%) and Chrysomelidae (25.86%). Similarly abundance calculated using Margalef index showed that Chrysomelids has the highest value of 7.327 followed by Staphylinidae. Carabids is the third most abundant family of beetles after Staphylinidae and Curculionidae in America (Johnson and Triplehorn, 2007).
Samplings at Kenyir lake collected only one individual of carabid beetle using malaise trap at Sungai Cicir. Poor assemblage of Carabid using malaise trap is due to the habits of Carabidae which does not fly. Carabid beetle is nocturnal and actively foraging for food when nightfall. This explains high collection of Carabid using light trap. This study indicates that Carabid is easily attracted to light. No carabids was collected at all using pitfall at Kenyir. The use of pitfall traps for studying the surface dwelling fauna has been criticised by various researchers (references in Lövei and Sunderland, 1996).
There was moderate abundance (Margalef index: 5.349) and high diversity (Simpson Diversity index: 0.967) of Carabid beetles at the limestone forests of Teluk Bewah. Fauziah (2006) reported low abundance (Margalef index: 2.394) and moderate diversity (Simpson Diversity index: 0.764) of carabid beetle in the limestone forests of Northeast Langkawi, the beetles being able to adapt to different niche. The microhabitat preferences of the functional groups of beetles are probably most strongly influenced by their feeding habits (Lassau et al., 2005). There are different foraging strategies used by different carabid species. For example, the absence of species of the phytophagous genera Amara and Harpalus in the forest interior might easily be explained by their nutrition, because their occurrence is critically dependent on the availability of seeds, preferably of grasses, umbellifers and crucifers (Thiele, 1977). Three species of Cychrini (Cychrus okamotoi, Cychropsis draconis and Cychropsis korelli), oligophagous predators of snails (Thiel, 1977), were rarely found in the grassland.
The thick virgin dipterocarp forest of Endau Rompin had a higher value of Simpson Diversity index (0.8561) than Dipetrocarp forest of Sungai Cicir (0.7217). The study plot at Sungai Cicir has less thick forest cover and was adjacent to about 30 m of open space before the river bank. Thinning maintained the forest-floor carabid assemblage well. Site characteristics, such as the amount of trees and bottom and field-layer vegetation, were important determinants of carabid assemblages. However the abundance value was not much different. Both study sites have the value of Margalef index at 2.0188 and 2.2165 for carabids, respectively. Vegetation structure can also influenced trap catches (Greenslade, 1964).
The sampling site at Sungai Cicir was in the Dipterocap forests which has bushes and dense herbs also next to the forest edge where there were several dense herbs growing at the river bank of Sungai Cicir. Thus higher niche and more microhabitat present for the carabid explaining higher diversity of carabid beetles.
Higher abundance of carabids at Teluk Bewah than Sungai Cicir site indicated that carabid assemblages in the forest edge were more similar to assemblages in the forest interior than to those in the grassland and that forest-associated carabid beetles did not avoid the edge zone near the forest. Heliola et al. (2001) and forest-grassland edges in South Africa (Kotze and Samways, 1999).
The limestone vegetation represented by Balsaminacea and Begoniceae species. Dipterocarp forest were dominated the lowlands with fig plant ficus, found in abundance (http://www.flyertalk.com/forum/archive/index.php/t-267851.html)
As in boreal forests in Finland (Heliola et al., 2001) and Canada only a few carabid species were restricted to the edge in our study. Two edge-associated species, P. yunnanus and Trichotichnus sp., showed a preference for forest edge, but were also found abundantly in adjacent forest interior and grassland. This contrasts with the temperate oak-hornbeam forests in Hungary, where several species of carabid beetles occurred primarily or exclusively at the forest edge which were abundant with bushes and dense herbs.
Results of assemblage of ground beetle in this study have shown that ecotourism does not affect the species diversity of ground beetles in the forests at Kenyir lake. This is because the visitors were mainly interested in the fishes and do not ventured into the forest which is protected and conserved. The habitat, niche and ecosystem of forests areas in Kenyir is thus undisturbed and well sustained.
Our appreciation goes to Department of Wildlife and National Parks (PERHILITAN) for facilitating our study at Kenyir. Thanks are due to Kamarulnizam, Shafrizan and Suwati for help in the field. Last but not least thank you to the boatman for safely bringing us to the base camp from Sungai Cicir at 0100 in the morning.
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