Butterfly species composition and diversity in a protected area of Karnataka , India

Field investigations were made to record the diversity of butterflies at six forest ranges in Nagarahole National Park (NNP), Karnataka during 2014 to 2015. 138 butterfly species were recorded from 94 genera, which belong to five families such as Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae, and Pieridae. Species composition varied significantly (F = 93.85; P < 0.05) among forest ranges in NNP; 113 butterfly species were common at different forest ranges in NNP, but 25 species were confined to specific forest ranges. Nymphalidae had the highest (47) species composition compared to other families. The genus Junonia was represented by six species, followed by Papilio and Eurema with five species each. The Shannon diversity index ranged between 4.49 and 4.59 and the Fisher alpha value ranged between 20.88 and 22.92. The Simpson and Shannon ‘J’ (Equitability) indices were 0.98 and 0.94, suggesting evenness between the six forests ranges. Thus, the present investigation provided insight into the butterflies of NNP and has instigated further research for restoration of forest habitats in NNP.


INTRODUCTION
Systematic studies on butterflies have been made in different parts of the world since the turn of the 18th century.Heppner (1998) has documented 19,238 butterfly species throughout the world.Over the past century, many researchers have significantly contributed to the field of butterfly ecology within the various ecosystems in India (Bingham, 1905(Bingham, , 1907;;Williams, Sharma and Sharma (2013), and Quareshi et al. (2014) have reported on the butterfly fauna in a few protected areas of central, northern and north-eastern parts of India.Radhakrishna and Lakshminaryana (2001) and Radhakrishna and Sharma (2002) have studied the butterfly fauna in Nilgiri Biosphere and Eravikulam National Park in South India.However, Watson (1890) published the butterflies of Mysore, Karnataka.Later, Yates (1933) published the butterflies of Bangalore and its neighborhood in Karnataka.Further, Radhakrishna and Ralot (2006) have reported the butterfly fauna of Biligiri Rangaswamy Wildlife Sanctuary, Karnataka.These three reports clearly suggested that researches of butterfly diversity in protected areas of Karnataka are wanting.In this region, butterflies play a pivotal role in environmental quality assessment in terrestrial ecosystems (Ghazol, 2002).Their presence serves as an indicator of habitat quality as well as regional vegetation.Moreover, butterflies are helpful to natural ecosystems by pollinating different plant species (Padhya et al., 2006).Further, they show migratory behavior, which is strictly seasonal; and because some are confined to specific habitats, they reveal the enriched biodiversity of that region.Therefore, butterflies become ideal candidates for biodiversity studies (Pullin et al., 1995;Thomas, 2001).Hence, emphasis has been placed on the study of butterfly diversity under various habitat conditions at protected areas of India in general and Karnataka in particular (Basavarajappa et al., 2018).Many butterfly species have exhibited population decline due to hunting, poaching and forest fires (Grewal, 1996).As a result, many butterfly species are facing threat in natural ecosystems including protected areas (Ghazol, 2002;Solomon and Rao, 2002).Hence, information on species composition, diversity, preferred host plants, food plants and distribution pattern of butterflies requires periodic updating in protected areas.

Study area
The Western Ghats, mountain range is considered a biodiversity hotspot, representing highly diversified mountain chains with three broad regions: north, south and central.The south region constitutes part of Hassan, Mysore and Kodagu districts in Karnataka (Kamath, 2001) and possesses the most diverse groups of endangered flora and fauna.The south region also contains many endemic species amidst tropical lowland, mountainous evergreen forests and grasslands (Kamath, 2001;Basavarajappa et al., 2018).
In this part of the state, the Nagarahole National Park (NNP) is located in the Southwestern region and is considered one of the biologically diverse regions of Karnataka.The NNP covers 643.39 km 2 and is in the Mysore and Kodagu districts (Figure 1) (Kamath, 2001).The terrain is undulating with small hills and an elevation range of 701 m above mean sea level (MSL) in the low lands and 950 m above sea level (Kamath, 2001).The NNP spreads from the Basavarajappa et al. 433 foothills of Western Ghats down to the Brahmagiri hills and extends south towards Bandipur National Park, Mudumalai and Wayanad Wildlife sanctuaries.The area is drained by perennial rivers and small to medium sized tributaries.The NNP receives 1000 to 1500 mm rainfall from southwest monsoons (June to September) and northeast monsoon (October to November).The western part receives relatively high rainfall and eastern part receives less precipitation.The temperature varies between 12 and 32°C (Kamath, 2001).These conditions favor varied vegetation that comprises scrubland to semi-evergreen forests (Basavarajappa, 2015).There are also microhabitats such as 'Hadlus' characterized by open grassland with moist clayey soil that supports grasses and sedges.

Methodology
The NNP is divided into seven major forest ranges: Antarsanthe, Anechowkur, Kallahalla, Nagarahole, Mattikuppe, D.B. Kuppe and Veeranahosahalli (Figure 1).The study area included areas within all forest ranges except Anechowkur (Table 1).Five study sites were randomly selected within each of the forest ranges.A distance of 3 to 4 kms was left between the study sites, in order to cover the different vegetation and topography of each range (Amala et al., 2011;Guptha et al., 2012;Kumar et al., 2007) (Table 1).The Pollard Walk Method was also adopted sometimes (Pollard et al., 1995;Kunte, 1997;Walpole and Sheldon, 1999) by fixing a 100-m permanent line transect in forest ranges.The butterflies were observed by traversing slowly (30 min per transect) and observing within 3 m radius of the observer (Caldas and Ribbis, 2003;Ramesh et al., 2010).Observations of butterflies were made from 8.00 to 12.00 h and 14.00 to 18.00 h (Kunte, 1997;Rajagopal et al., 2011) and photographed using a Canon and Nikon Power shot camera with appropriate megapixel lenses.Each study site was visited once in a quarter in all the six forest ranges.Field photographed butterflies were identified with the help of field guides.Capturing of butterflies is strictly prohibited in NNP and hence, a visual count method (VCM) was adopted during the present investigation.

Statistical analysis
Analysis of variance (ANOVA) was used (Saha, 2009).The butterfly diversity was calculated by using PAST version 2.10.The α diversity of butterfly species was calculated by using Shannon Diversity Index (H 1 ) that combines the number of species within a range with the relative abundance of each species (Maguran, 2004).Shannon Diversity Index (H 1 ): H'= -∑ (pi ln pi), where pi is the proportion of the i th species in the total sample and In pi is the natural log of pi.
The number of species (species richness) in the community and their evenness in abundance (or equitability) are the two parameters that define 'H'.The evenness of species within a range was calculated by using Pielou's Evenness Index (J 1 ) to identify the variation within the community among species.
Pielou's Evenness Index: J 1 = H'/ ln S, where S is the number of species present in the site and H' is the diversity index.
Moreover, the value of J 1 ranges from 0 to 1. Lesser variation within the communities among the species results in higher value of J 1 .Further, β (beta) diversity of butterflies was calculated by using Sorensen's Index.It is a simple method used to identify the beta (β) diversity and indicates the similarity of species distribution within the study sites.Sorensen's Similarity Index is defined as: where S1= total number of species recorded in the first community, S2 = total number of species recorded in the second community and c = the number of species common to both communities.
Moreover, the value of Sorensen's Index ranges from 0 to 1.If the value is 0, there is no species overlap between the communities and if the value is 1, the same species are found in both communities as per Maguran (2004).

Butterfly species composition
Altogether 138 butterfly species were recorded, of which Dry deciduous forest, scrub forest vegetation along with eucalyptus plantation.
113 species were observed at six forest ranges that comprised 81.9% of the total; the remaining 25 butterfly species (18.1%) were specific in their distribution, that is, found only in a few forest ranges in NNP.The butterflies found at NNP belonged to five families, namely: Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae and Pieridae and their species compositions were respectively 24, 21, 39, 19 and 10 (Tables 2 to 4).Among the Hesperiidae family, there were 22 genera with 24 species and in the Lycanidae family, 19 genera with 21 species found at six forest ranges (Table 2).For the genera Notocrypta and Taractrocera, two species were recorded in the Hesperiidae family.Two species were recorded in the genus Chilades within the Lycaenidae family (Table 2).Further, 39 butterfly species belonging to the Nymphalidae family were found in NNP (Table 3).Interestingly, the genus Junonia has the highest (six) recorded species and it was followed by the genera Mycalesis and Ypthima with four species each.However, the genera Ariadne, Danaus, Euploea, Hypolimnas, Lethe, Melanitis and Tirumala have only two species each recorded from the sampling sites (Table 3).Thus, the Nymphalidae family exhibited the highest diversity, with 21 genera and 39 species in NNP as compared to all other families.There were 11 genera with 19 species found in the Pieridae family, and only four genera with 10 species were recorded in the Papilionidae family in the NNP.Among Pieridae butterflies, the genus Eurema has the highest recorded (five) species and three species were observed for the genus Colotis.However, the genera Catopsilia and Ixias were represented by two observed species, each in the Pieridae family (Table 4).
In Papilionidae, the genus Papilio had the highest recorded (four) species, and it was followed by Graphium with three species and Atrophaneura with two species (Table 4).Commonly occurring Papilio species are Papilio demoleus, Papilio helenus, Papilio memnon, and Papilio polytes, and the Graphium species are Graphium sarpedon, Graphium doson and Graphium agamemnon (Table 4).Thus, the Pieridae family was represented with 7 genera and 19 species, and Papilionidae family with only 4 genera and 10 species in the NNP (Table 4).Thus, Nymphalidae, Lycaenidae, Hesperiidae, Pieridae and Papilionidae family species compositions were respectively 47, 30, 29, 20 and 10 (Table 5).Analysis of variance of butterfly species observations indicated that there was a significant variation (F = 96.68;P < 0.05) between the butterfly species observed in different families within the NNP.However, there was no significant variation (F = 0.053; P > 0.05) between the butterfly species that occurred among the forest ranges in NNP (Table 6).diversity) is a useful index to measure the difference or similarities of variety and abundance of species between the habitats.During the present study, Sorenson's Index was used to compare the species recorded in each and every forest range, but the values did not indicate much variation between the forest ranges with values ranging between 0.9444 and 0.9881 (Table 9).The diversity curve showed a typical decreasing trend for all the six forest ranges, and thus displayed the properties typically with respect to diversity profile of different forest ranges in the NNP (Figure 2).All the curves showed a unique type of variation and similarity in butterfly species distribution at six forest ranges.Moreover, curves showed more values towards the alpha (α) indicating all the ranges revealed dominance in their butterfly species diversity.

DISCUSSION
During the present investigation, 138 butterfly species were recorded from five lepidopteron families in the NNP.The 'H' indexes (4.49 and 4.59) and Fisher alpha values (20.88 and 22.92) indicated the presence of good butterfly diversity, with evenness between the six forests ranges in the NNP.Further, Sorenson's Index (ß diversity) did not indicate much variation between the forest ranges, and displayed the properties typically with respect to diversity profiles of the different forest ranges in the NNP.However, five lepidopteron families such as Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae and Pieridae were represented by 24, 21, 39, 19 and 10 species; and there was a significant variation between forest ranges in the NNP.Butterflies prefer specific habitats (Sreekumar and Balakrishna, 2001), to avail themselves of available resources for survival in the forest ecosystem.They show diverse feeding habits, and the varied forest habitats offer suitable sites for breeding, foraging and resting during different stages in their life cycle (Santhosh and Basavarajappa, 2017).Interestingly, the NNP has a good annual precipitation, and favorable, congenial temperature and relative humidity during various seasons in most of the forest ranges in the NNP.Moreover, the mountainous terrains (undulating with small to medium sized hills) are covered with evergreen and deciduous tree species at different forest ranges.The foothills and lowland areas are enriched with herbaceous plant species, shrubby vegetation at open grassy areas, and all along the banks of perennial rivers and small to medium sized tributaries amidst the NNP (Kamath, 2001).Perhaps, all these life-supporting conditions might have contributed to the good values of the butterfly diversity index, with evenness among the forest ranges in the NNP.Moreover, certain nectar producing tree species might have provided nectar for adult butterflies; and foliage from trees, shrubs and herbaceous vegetation could have provided the food for larval forms.Further, the wild grasses and sedges growing in open areas and all along the banks of perennial rivers and small to medium sized tributaries amidst the NNP might have provided congenial life supporting stopover sites during different stages in the life cycle of butterflies.Furthermore, a few microhabitats namely 'Hadlus,' characterized by open grassland with moist clayey soil, could have supplemented the butterfly's mineral nutritional requirements for However 25 butterfly species, constituting 18.1%, were more specific in their distribution in the NNP.The requirement of foliage as food for the growing larvae, and nectar and minerals as a nutritional source for the few adult butterfly species, are not alike for these two different stages of reproductive development.Moreover, it is obvious that nutritional requirements including need for water, food plants and their chemical constituents in relation to the larval feeding, growth rate and habitat preferences are not uniform among the butterfly species.Perhaps, all these variations might haveinfluenced the distribution of butterfly species, which belong to Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae and Pieridae families, differently at NFR, KFR, MFR, AFR and VFR and DBKFR in the NNP.This clearly indicated that certain butterfly species prefer specific habitats amidst the forest ecosystems; the temporal and spatial distribution of the butterfly species is directly correlated with the floral diversity and ecological conditions of the region (Sreekumar and Balakrishna, 2001).Thus, butterflies are ubiquitous creatures, and exhibit unique evolutionary adaptations that enable them to associate with diversified ecosystems (Pierce et al., 2002).
Similar observations were made by Nimbalkar et al. (2011) and Atluri et al. (2012).However, butterfly species habitat specificity requires thorough in-depth studies to better understand the butterfly biology, host plant ecology, and the food plants distribution and abundance in the NNP.Such information is essential to establish sound policy measures aimed at restoring existing flora among forest ecosystems in general, and protected areas in particular (Kunte, 1997;Padhya et al., 2006).Further, seasonal migration of butterfly species and occurrence of few butterflies within a particular forest range help to reveal their unique life supporting requirements to complete their life cycle during their visit to such ecosystems.
All these features indicate the importance of more additional studies to record periodically, and more systematically, the butterfly species' composition, species diversity, habitat quality and distribution pattern in fragile habitats such as the NNP.Such studies could provide insight about the status of butterfly species, and in turn to initiate further research for their conservation (Pullin et al., 1995;Kunte et al., 2012).Our observations are in agreement with the observations of Ghazol (2002), Kunte (1997 and2001), Kumar et al. (2007), Amala et al. (2011), Guptha et al. (2012), Kunte et al. (2012), Tewari and Rawat (2013) and Quareshi et al. (2014).Thus, all these authors have emphasized the need for additional butterfly studies in protected areas of India.

Conclusion
A total of 138 butterfly species from five lepidopteron families were recorded in the NNP.Among them, 113 species were common in their appearance at all forest ranges in the NNP.This was evidenced in the Simpson 'J' (Equitability) and Shannon 'H' indices of evenness for all butterfly species encountered, except 25 butterfly species, which exhibited habitat specificity.Further, the Shannon diversity index was 4.49 to 4.59 with good Fisher alpha value and Sorenson's Index.Thus, the biodiversity profile showed a typical decreasing trend and displayed the good diversity profile of butterflies amidst the NNP.The presence of butterflies is very essential for pollinating different plant species within protected natural ecosystems.Moreover, seasonal migratory patterns of these winged creatures with preferences for given habitats indicates their need to avail themselves of particular prevailing conditions for their survival.Therefore, assays of butterfly populations should be updated periodically so as to reveal species diversity and distribution patterns that could help provide an insight about the population statuses of these varied species, and in turn to initiate further research for their conservation.

Figure 1 .
Figure 1.Map showing the study areas at Nagarahole National Park.

Figure 2 .
Figure 2. Butterfly species diversity profile at Nagarahole National Park.

Table 1 .
Physiographic features of six forest ranges in Nagarahole National Park.

Table 2 .
Scientific and common names of Hesperiidae and Lycanidae family members found at Nagarahole National Park.Around 25 butterfly species were not evenly distributed in all the forest ranges, but they were found at specific forest ranges in the NNP (Table7).In general, five species of Hesperiidae, nine species of Lycaenidae, eight species of Nymphalidae, two species of Papilionidae, and one species of Pieridae were confined to specific forest ranges in the NNP.The Cupitha punrreea, Curitis acuta and Graphium nomius were found only at D.B. Kuppe Forest Range (DBKFR).

Table 3 .
Scientific and common names of Nymphalidae family members found at Nagarahole National Park.

Table 8
(Equitability)indices revealed that the distribution of a majority of butterfly species within the six forest ranges was almost the same (0.98) and (0.94), and suggested the evenness between the six forests ranges.The Sorenson's Index (ß

Table 4 .
Scientific and common names of Pieridae and Papilionidae family members found at Nagarahole National Park

Table 5 .
No. of butterfly species and their families observed at different Forest Ranges in Nagarahole National Park Data is based on Tables2 to 5. AFR: Antharasanthe Forest Range; DBKFR: D. B. Kuppe Forest Range; KFR: Kallahalla Forest Range; MFR: Mattikuppe Forest Range; NFR: Nagarahole Forest Range; VRF: Veeranahosahalli Forest Range.

Table 6 .
ANOVA for butterfly species found between and within Forest Ranges in Nagarahole National Park.
Each value is a mean of 120 observations; *Value is significant at 5% level; ** Value is not significant.Data is based on Tables1, 2, 3, 4 and 5.

Table 7 .
Butterfly species found at specific Forest Ranges in Nagarahole National Park.
B. Kuppe Forest Range; +: Present, -: Absent.certain species.Perhaps, all these prevailing, biologically rich life supporting conditions at different forest ranges in the NNP might have supported as much as 113 butterfly species.

Table 8 .
Butterfly species diversity Index in Nagarahole National Park.

Table 9 .
Beta diversity (Sorenson's Index) of butterfly species in Nagarahole National Park. S/N