The insect fauna of Tenompok Forest Reserve in Sabah, Malaysia

The insect fauna in Tenompok Forest Reserve, adjacent to Mount Kinabalu in Sabah was surveyed. Nocturnal insect diversity was moderately high, compared to other forest reserves surveyed earlier. Species richness, however, was moderate, with an average of 73 species from 84 individuals recorded from a 1m2 area of the light-trapping cloth. At least 20 Bornean endemic insect species were recorded from this rapid biodiversity assessment, which include 19 moth species and one beetle species. The endemics and other insects of conservation interest recorded during the survey provide salient information to enhance the conservation effort of this forest which connects Kinabalu Park and the Crocker Range Park. Such information provides inputs towards recommendations on high conservation value (HCV) of the area that would be incorporated in the formulation of the forest management plan. Issues affecting the insect fauna and recommendations on insect diversity enhancement and conservation are highlighted in this paper.


INTRODUCTION
The Malaysian state of Sabah in Borneo is known for its remarkable biodiversity and iconic wildlife species (Oldfield 2014), including insects (Chung et al. 2015). These are the natural treasures that need to be protected and conserved, as stipulated in the Sabah Biodiversity Strategy 2012-2022(Anon. 2012). This strategy is in line with the National Policy on Biological Diversity (Anon. 2016) that seeks to conserve Malaysia's biodiversity and to ensure that its components are utilised in a sustainable manner for continued progress and socioeconomic development. In line with this strategy, the Sabah Forestry Department has been in the forefront in implementing biodiversity conservation programmes under the Heart of Borneo (HoB) Initiative. The HoB initiative is a 'three countries -one vision' responsibility, which is to protect and conserve the rich biodiversity within this area. It is a voluntary transboundary cooperation aimed at conserving and managing the ecologically inter-connected highlands of Borneo and parts of the adjacent foothills and lowland rainforests, which straddle the borders of three ASEAN countries, covering an area of approximately 2,00,000km 2 (Anon. 2013).
Insect numbers are declining globally (Basset & Lamarre 2019). Hence, much attention should be given to this group of living organisms. Within the HoB initiative, biodiversity documentation has been extensively carried out in Sabah, encompassing insect diversity as well, e.g., Chung et al. (2013Chung et al. ( , 2016a, since much is still unknown about the insect fauna compared to the large and more charismatic animals (Anon. 2012). Despite their small size in comparison with other wildlife, they are ecologically important in the functioning of the tropical ecosystems because of their high species richness and abundance (Hill & Abang 2005).
This scientific survey was carried out on 5-9 September 2016, with the base camp located at Kg. Kilimu in Ranau. The objectives of this study were to document the insect fauna of Tenompok Forest Reserve (FR) under the HoB Initiative, and to investigate issues affecting insect diversity, as well as to provide recommendations that would contribute towards biodiversity conservation of the study area. Research findings from this study would enhance this area as a Class I FR to promote the connectivity between Kinabalu Park (KP) and Crocker Range Park (CRP) under the Ecolinc Kinabalu project. This project is a connectivity conservation effort initiated by Sabah Parks to improve ecological connectivity between KP and CRP. Although KP and CRP reside on the same range, the parks are physically separated from each other; their boundaries are separated by a distance of approximately 10km at the closest point. Forest fragmentation that occurs within these two protected areas due to uncontrolled deforestation and expansion of agriculture and human activities has been an issue.

Study area
Tenompok FR (Figure 1 and Image 1) is a Class I Protection FR and is situated adjacent to Mount Kinabalu (4,095m) (Image 2), the tallest mountain in Malaysia. It is located beside the Kota Kinabalu-Ranau highway, approximately 92km east of Kota Kinabalu and 19km west of Ranau. With an area of 1,984ha the forest reserve is under the jurisdiction of the Ranau District Forestry Officer. It is surrounded by villages ('kampung' in Malay and often used as 'Kg.' before the name of the village), namely Kg. Bundu Tuhan in the east, Kg. Torolobou and Kg. Toboh in the south, Kg. Kiau in the north, and Kg. Tiong in the west.
The forest is mountainous, (1,040-1,650 m), with slope amplitudes in excess of 300m and normally greater than 25 o . The soil associations in this reserve are mainly Croker and Trusmadi, based on the soil classification in Sabah (Acres et al. 1975). The reserve is a water catchment area for Kg. Bundu Tuhan and many other villages. Several rivers flow from this reserve, namely Liodan, Kenipir, Terleboh, Luminanap, Kuriau, Kipalapok and Tomis. The vegetation type of the reserve is largely lower montane forest.

Insect sampling methods
Light trap was used to sample nocturnal insects while sweep nets and forceps were used to sample diurnal insects.

Light trap
The trap consists of a vertical white sheet (2 X 2 m) illuminated by a 250W mercury-lithium bulb. It was powered by a portable Yamaha generator. The trap was set up in an open area facing the forest reserve, from 19.00 to 21.00 h. A GPS (Model: Garmin GPSMAP 60CSx) was used to determine the coordinates of each sampling site. Temperature and relative humidity were taken with a digital hygrometer from Extech Instruments (model no. 445702). The details of each trapping position are given in Table 1.

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To evaluate diversity of the sampling area, insect species and individuals (≥ 5mm) within the 1 X 1 m 2 at the centre of the white cloth were enumerated from 20.30 to 21.00 h. This is a rapid biodiversity assessment method because by the end of the sampling time, morphospecies and individual numbers can be obtained. The data was used to calculate diversity indices. This method is simple, fast and can be carried out by noninsect specialists. To avoid compounding human error, the same staff was assigned to count the species and individual numbers throughout the sampling period. Light trapping was conducted within the compound of the Tenompok nursery (approximately 0.5 acre) but facing different positions of the forest on different nights. The term 'position' is used here rather than site because of the limited space within the nursery and the authors acknowledge that these positions may not be independent of one another. There were no other suitable sites for setting up the light trap in other parts of the forest due to logistical difficulties and safety reasons at night.

Sweep net and manual collection
Sweep nets were used to collect flying insects while other insects were sampled using fine forceps. Butterflies were put in triangle papers while other specimens were J TT put in vials with 75% ethanol solution. Sampling was conducted along the trails established previously and also old skid trails. Details of the daytime sampling sites are listed in Table 2.

Insect specimens and identification
In this survey, focus was given to certain insect groups, i.e., butterflies, moths, and beetles. Other insects were recorded when encountered but without any concerted effort. Only insects with conservation interest and potential indicator insect species were sampled, so as to minimize the workload at the laboratory in preparing the specimens for identification. This is also one of the best practices adopted to minimize stress and disturbance to biodiversity, as pointed out by Costello et al. (2016) and Didham et al. (2019) on field work ethics in biological research. Photographs were taken with DSLR Nikon D800E and Nikon Coolpix cameras to facilitate identification. Common insects were not sampled but photographs were taken for record purposes. Some insect photos were not taken on the white sheet (on purpose) after the enumeration was conducted.

Diversity indices
The diversity indices, namely Shannon Wiener, Simpson, and Fisher Alpha were calculated through a diversity analysis software by Seaby & Henderson (2007), based on Magurran (2004) and Southwood & Henderson (2000). Merits and limitations of diversity measurements are provided by Beck & Schwanghart (2010). Knowing that biodiversity is a multifaceted phenomenon and the existence of various methods in diversity measurements, we used the same few indices that were also applied in the past insect surveys Image 2. Mt. Kinabalu, as viewed from Kg. Bundu Tuhan, located beside Tenompok FR.

Shannon Wiener Index (H')
This index is calculated in the following way: where p i is the proportion of individuals found in species i. For a well-sampled community, we can estimate this proportion as p i = n i /N, where n i is the number of individuals in species i and N is the total number of individuals in the community. Since by definition the p i s will all be between zero and one, the natural log makes all of the terms of the summation negative, which is why we take the inverse of the sum. Typical values are generally between 1.5 and 3.5 in most ecological studies. The Shannon index increases as both the richness and the evenness of the community increase.

Simpson Index (D)
This index is based on the probability of any two individuals drawn at random from an infinitely large community belonging to the same species: where again p i is the proportion of individuals found in species i. For a finite community, this is D = ∑ n i (n i -1)/N(N -1) D is a measure of dominance, so as D increases, diversity (in the sense of evenness) decreases. Thus, Simpsonʼs index is usually reported as its complement 1-D (or sometimes 1/D or -lnD). In Seaby & Henderson (2007), it is reported as 1/D, which is also known as Simpson's reciprocal index. It is heavily weighted towards the most abundant species in the sample while less sensitive to species richness (Magurran 1988). Hence, the value will be low if there is a very abundant species.

Fisher Alpha Index (S)
This is a parametric index of diversity that assumes that the abundance of species follows the log series distribution: αx, αx 2 /2, αx 3 /3, … αx n /n where each term gives the number of species predicted to have 1,2,3,....n individuals in the sample. The index is the alpha parameter. This is a useful index, which has been widely used. It is estimated by an iterative procedure that may take an appreciable amount of time with large data sets.

Insect fauna in conservation implications
Within ecological science, there has been a large focus on whether a reduction in the diversity of the entities of organisms -biodiversity -is impacting ecological process and ecological services. Various studies have highlighted that there is indeed a positive relationship between diversity and functioning in terms of biomass production and some other functions (Balvanera et al. 2006;Cardinale et al. 2006;Isbell et al. 2011). Biodiversity conservation should focus on ecosystem function, rather than on a particular species, that could serve as a framework for addressing the current urgent conservation challenges (Peh & Lewis 2012). In this study, it is hoped that the documentation of insect fauna would provide an impetus for biodiversity conservation of Tenompok FR as insects are ecologically important in the functioning of the ecosystem.

Overall insect diversity
The nocturnal insect diversity was moderately high, as shown in Table 3. The mean Shannon Index was 4.2 while Simpson index was 206.5 and Fisher alpha index was 260.2. Species number and abundance, however, were moderate, with an average of 77 species and 84 individuals recorded within a 1m 2 light-trapping cloth.
During light-trapping, the temperature was cold, between 17°C and 18°C with relatively high humidity, between 88% and 91% ( Table 1). The distribution of insect species from the light-trapping positions is reflected in the species-rank abundance curves in Figure  2. Position C recorded the most species (85), as indicated with the long tail graph, and the Shannon's index of 4.37 was the highest among the three positions. Position C also shows the steepest curve, with six specimens from one interesting moth species, Areas galactina. This was the most prominent species throughout the three nights of light-trapping.
When the nocturnal insect richness is compared with other forest reserves, Tenompok FR (in red) appeared to be moderate as it is ranked 8 th of the 19 sites in Sabah (Figure 3a). In terms of nocturnal insect diversity, it is moderately high (ranked 5 th of the 19 sites) and almost comparable to many other montane forest reserves sampled previously, such as Bukit Hampuan FR and Crocker Range FR (Figure 3b).
Many Bornean endemic species were recorded from Tenompok FR during the survey, as listed in Table 4.

Butterflies (Lepidoptera)
At least 13 butterfly species were recorded, as listed in Appendix 1. Most of the butterflies were recorded at Sg. Liden in Kg. Bundu Tuhan, at the fringe of the forest reserve. Among the interesting butterflies sighted were    (Otsuka 2001).

Moths (Lepidoptera)
Some 102 moth species were recorded during this study (Appendix 2). A total of 19 endemic species were documented (Image 3), which represents 19% of the moths recorded during the survey. In terms of percentage, more endemic moths were recorded in Crocker Range FR (Chung 2016a) and Bukit Hampuan FR (Chung 2013), with 33% and 23% respectively. In this paper, all Arctiidae and Lymantriidae moths are classified under Erebidae based on DNA analyses by Zahiri et al. (2010Zahiri et al. ( & 2011 and taxonomic changes highlighted by Holloway (2011).

Beetles (Coleoptera)
At least nine species of macro beetles were documented (Appendix 3). One Bornean endemic species was recorded, namely Odontolabis leuthneri (Image 4) of the telodonte form (Fujita 2010). This stag beetle was sighted during day time at 1,600m. A large long-horned beetle, Batocera tigris, (about 65mm) was attracted to the light trap at the Tenompok nursery. It is a rare beetle in Borneo although it is known to be distributed in Peninsular Malaysia, Thailand, Sumatra, Java and Borneo. Quite a number of the soldier beetles, Mimopolemius sp. of the family Cantharidae were sighted while trekking along the trail at Kg. Bundu Tuhan.

Other insects
At least 17 other insect species were recorded which include termites, bugs, fig wasps, honeybees, ants, night wasps, praying mantis, dragonflies, damselflies and

Further pertinent observations on selected insects during the survey Tiger Moth Areas galactina (Lepidoptera: Erebidae: Arctiinae)
This was the commonest moth species encountered during the three nights of light-trapping at the Tenompok FR nursery. It is a spectacular species because of its vibrant colours and interesting pattern (Image 5a & b). According to Holloway (1988), this insect cannot be confused with any other; the reticulate black markings of the forewings and the black spots on patagia and tegulae distinguish it from Spilosoma of the ericsoni group. The length of the forewings is 32-35 mm for male and 40-42 mm for female. It is distributed from northern India and southern China to Sundaland and the Philippines. Although widely distributed, it is not commonly encountered, normally found between 1,200m and 2,000m. In this survey, it was recorded from 1,300m. Although it is predominantly a montane species, it has been recorded in the lowland forest, such as Danum Valley (AYC Chung, unpublished data). There has been no information documented on the host plants.

Tiger Moth Amerila spp. (Lepidoptera: Erebidae: Arctiinae)
Two species of Amerila were recorded during the survey, namely Amerila astreus (Image 6a) and Amerila omissa (Image 6b-d). Like that of Areas galactina, both species are spectacular, with strikingly pink legs. Both were attracted to the light trap at the Tenompok FR nursery. They are similar externally in appearance except for the dorsal part of the abdomen. In A. astreus, it is entirely pink but only apically so in A. omissa. One of the interesting defense mechanisms that was observed during the survey was the secretion of acrid smelling yellow froth from the cervical glands at the anterior of the thorax when the moth was disturbed.

Carton ball-like termite nests (Termitidae: Nasutitermitinae)
While trekking along the trail (Sampling Site 3) from Kg Bundu Tuhan, at least 10 ball-like termite nests were sighted from 1,300 to 1,461 m. They were found on tree trunks (Image 7a) or hanging on tree branches (Image 7b), some of which were about the size of a football. The nests were constructed from soil and litter, mixed with termite saliva. This is interesting because it was rarely observed in previous surveys in other forest reserves, e.g., Chung et al. (2013Chung et al. ( , 2016a. The termites belong to the Nasutiterminae group because of their pointednose soldiers. They were observed carrying their food back to the nest openly in an organized manner (Image 7c).

Issues indirectly affecting insect diversity
Among many of the forest reserves in Sabah, Tenompok FR is considered one of those that is wellprotected, with active participation from the local communities. The reserve is a source of water supply for many of the adjacent villages. Hence, the local communities have formed a committee to monitor and take care of the resources in the reserve. Sign boards were put up to warn trespassers into the reserve (Image 8). During the survey, a few villagers joined the researchers, indicating that they were keen to know more about the resources in the reserve.
Tenompok FR is located between Kinabalu Park and the Crocker Range Park. Hence, the reserve is important as a corridor connecting the two park areas, especially for wildlife movement. It is a stepping stone approach for movement of birds and insects, and the adverse impacts on inbreeding and decline in genetic diversity can be reduced. Staff from Sabah Parks and the Ecolinc project also participated in this survey to enhance their info on this area. The Ecolinc project was initiated some eight years ago under the EU-REDD+ programme to promote and enhance awareness to the local communities on forest connectivity and related activities on climate change and sustainable forest management. ECOLINC is the acronym for ECOlogical Linkage (conserving Sabah's heritage, empowering INdigenous Communities).
Although the forest is considered well-protected, the survey team also spotted a few animal traps in the forest. Among them was a pangolin trap at the base of a big tree (Image 9a). A few tree trunks were partly burnt previously, presumably to harvest honey from the stingless bees (Image 9b).
It is important for the local communities to work handin-hand with the relevant departments and agencies to tackle various issues pertaining to forest biodiversity which could indirectly affect insect population (Nilus et al. 2013). As shown in this brief study, relatively high diversity of insects and many endemic species were recorded. Hence, it is important to continue to protect the forest for its interesting biodiversity, in line with the goals of the Sabah Biodiversity Strategy (Anon. 2012), guided by the National Policy on Biodiversity.

Impediments in insect fauna study
Impediments to identification are one of the major reasons why insect data are not the prime focus in conservation, as the group is perceived too big and unwieldy to use. Misidentification potentially lead to overestimating or underestimating species richness, and these problems can extremely compromise research J TT Image 8. A signage put up by the villagers to warn trespassers. Image 7a. An old pangolin trap at the base of a big tree. Image 7b. A set ablaze, p bee honey. Image 9a. An old pangolin trap at the base of a big tree. Image 9b. A tree trunk that had been set ablaze, presumably for the stingless bee honey. Image 7a. An old pangolin trap at the base of a big tree. Image 7b. A tree trunk that had been set ablaze, presumably for the stingless bee honey.
involving diversity. Poor taxonomy can jeopardize the understanding of ecological patterns since they are based on richness and measurement of species turnover between sites, respectively.
For biodiversity conservation, taxonomy is important, primarily because in order to protect a taxon it is essential know it first, and secondly, because no conservation action can protect undescribed species. In this study, the enumeration on nocturnal insect diversity was based on morphospecies. Photographs of insects were taken and identification was based on various publications and the scientific reference collection at the Forest Research Centre, Sepilok. Various experts on certain insect groups also provided input in the identification of insects in this study.

CONCLUSION
From this study, the nocturnal insect diversity in Tenompok FR was moderately high when compared to other forest reserves surveyed earlier. Many endemic species were recorded in this montane forest.
The pioneer data from this rapid biodiversity assessment will serve as baseline information for other research work in future. Local university students could use these data for comparative study for long-term monitoring on the insect diversity status of Tenompok FR. The endemics and insect species with conservation interest recorded during the survey provide salient information to enhance the conservation of this forest as a Class I FR. Such information can also be used in promoting nature tourism in Tenompok which is located adjacent to the touristic Kinabalu Park and Crocker Range Park.
Issues, such as poaching and encroachment may indirectly affect the insect fauna. Relevant agencies would have to work hand-in-hand to tackle the issues with the local communities. Public awareness and environmental education would have to be enhanced among the villagers and their children who are living adjacent to the reserve to instill on them the importance of biodiversity conservation.