Diversity of Butterflies (Lepidoptera: Rhopalocera) of Howrah District, West Bengal, India

Journal of Entomology and Zoology Studies 2017; 5(6): 815-828 E-ISSN: 2320-7078 P-ISSN: 2349-6800 Diversity of butterflies (Lepidoptera: JEZS 2017; 5(6): 815-828 © 2017 JEZS Rhopalocera) of Howrah district, West Bengal, Received: 22-09-2017 Accepted: 23-10-2017 India Saurav Dwari Plant Taxonomy, Biosystematics and Molecular Taxonomy Saurav Dwari, Amal Kumar Mondal and Subhadeep Chowdhury Laboratory, UGC-DRS-SAP, Department of Botany & Abstract Forestry, Vidyasagar University, Butterflies are one of the most attractive insects in the world which have received a reasonable amount of Midnapore, West Bengal, India attention throughout the world. Our result shows that butterflies of Howrah district, West Bengal, India Amal Kumar Mondal comprises of 106 species including 75 genera and 6 families. Out of these 6 families Lycaenidae and Plant Taxonomy, Biosystematics Nymphalidae were to found to be the most dominant in nature. During our studies, we found Grass and Molecular Taxonomy Jewel, the smallest butterfly in India and The Blue Mormon, the largest butterfly of South West Bengal Laboratory, UGC-DRS-SAP, as well as second largest in India. Common Shot Silverline, Angle Sunbeam, Bengal Plains Blue Royal Department of Botany & and Indian Oak Blue recorded the first time from the district. Rapid urbanization and building of Forestry, Vidyasagar University, industries are the serious threats to butterfly diversity in this district. So, preparation of a list of butterfly Midnapore, West Bengal, India species is necessary for further references to understand the changes of their diversity. Subhadeep Chowdhury Keywords: Butterflies, Howrah, West Bengal, India, lycaenidae, Urbanization Krishnachak, Dhurkhali, Howrah, West Bengal, India 1. Introduction Butterflies are one of the most attractive insect in the world and taxonomically well studied groups and have received a reasonable amount of attention throughout the world [1]. They are important pollinators and food chain components of an ecosystem. Being potential pollinating agents of their nectar plants as well as indicators of the health and quality of their host plants and the ecosystem as a whole, exploration of the butterfly fauna thus becomes important in identifying and preserving potential habitats under threat. Butterflies are potentially useful ecological indicators of urbanization because they can be readily surveyed, and they are sensitive to changes in microclimate, temperature, solar radiation, and the availability of host plants for ovipositing and larval development [2, 3]. Butterflies are recognized as focal species [4] of conservation in several areas of the world . There are several issues regarding declining species richness, diversity and abundance of which hurried development and urbanization are the main [5-7]. The reduction in the amount and the quality of natural habitats associated with the urban development negatively affects the nature of biodiversity [8]. th [9] In India research on butterflies started in the 19 century . Many works have been done by [10-15] different researchers in India. The number of Indian butterflies amount to one fifth of the world’s butterfly species [16]. From India 1501 species of butterflies are recorded [11] and in West Bengal its number is 452 [17]. Similarly, such works have been carried out in Calcutta and its associated areas also [18-21]. But there are no previous records of butterflies of Howrah district except Diversity of Butterflies in the Acharya Jagadish Chandra Bose Indian Botanic [22] Garden, Howrah, West Bengal . We are representing here butterfly diversity of Howrah district. Due to important ecosystem services of butterflies and rapid habitat degradation, it is very important to study about the butterflies’ diversity of this district along with their distribution and abundance. Correspondence Saurav Dwari 2. Material and Methods Plant Taxonomy, Biosystematics 2.1 Study area and Molecular Taxonomy Howrah district lies between 22°48′ N and 22°12′ N latitudes and between 88°23′ E and 87°50′ Laboratory, UGC-DRS-SAP, E longitudes which covers 467 km2, situated in the eastern parts of India within the state of Department of Botany & Forestry, Vidyasagar University, West Bengal (Figure 1). The district bounded by the Rupnarayan River on its West and the Midnapore, West Bengal, India South-West side and east and the south-east side by Bhagirathi-Hooghly River. ~ 815 ~ Journal of Entomology and Zoology Studies On the north side, the boundary is an artificial one except for c. Measurement of evenness the Bally canal on the north-east and the Damodar River in For calculating the evenness of species, the Pielou’s Evenness the north-west. The annual normal rainfall is 1461 millimeter Index (e) was used [35]. per year. The annual maximum temperature varies between e = H / In S 32-39 °C, whereas the minimum temperature varies between H = Shannon – Wiener diversity index 8-10 °C. We divided the whole district into four different S = total number of species in the sample regions based on their geographical similarities, namely the Upper Damodar River Basin (UDRB), the Lower Damodar d. Dominance and Simpson Index River Basin (LDRB), the Semi Urbanized Zone (SUZ) and D = ∑ (ni/n)2 where ni is number of individuals of taxon i. the Industrial Zone (IZ). The Upper Damodar River Basin Dominance = 1-Simpson index. Ranges from 0 (all taxa are (UDRB) comprises of Udaynarayanpur, Amta I & II and equally present) to 1 (one taxon dominates the community Bagnan I blocks. The Lower Damodar River Basin (LDRB) completely). comprises of Bagnan II, Uluberia I, Shyampur I & II blocks. Simpson index 1-D. Measures 'evenness' of the community The Semi Urbanized Zone (SUZ) comprises of Uluberia II, from 0 to 1. Dominance and Simpson indices are often used Jagatballavpur, Panchla blocks and the Industrial Zone (IZ) interchangeably. includes Domjur, Bally Jagachha, Howrah Sadar and Sankrail blocks. The different natural habitats within the study area are e. Species area hypothesis and Species energy hypothesis also represented (Figure 2). Species area hypothesis suggested that large area supports more species. Species energy hypothesis suggested that 2.2 Sampling techniques and species identification greater productivity permit the existence of more species. Different habitats of this district were surveyed during April This represents current conditions and information on 2013 to February 2017 by using line transect method. ecosystem. Information on butterfly fauna are based on observation from 07:00 to 11:00 hr and 14:00 to 18:00 hr. Butterfly species f. SHE Analysis density was assessed quantitatively across different habitats SHE actually denotes the role of each diversity components in (block wise). Transects were walked once a month in each community and it employed to separate species diversity into block to follow Pollard Walk Method [23, 24] for recording the its richness and evenness components. SHE analysis [36, 37] butterflies. A slow 180 degree visual sweep was performed requires a matrix of integer abundance data (counts), with during walking. Along with that Visual encounter survey and taxa in rows and samples in columns. The program calculates Opportunistic survey methods are also applied during the log species abundance (ln S), Shannon index (H) and log study period. evenness (ln E = H – ln S) for the first sample. Then the Modifications of the line transect count were used to second sample is added to the first, and the process continues. determine butterfly richness and abundance [25]. In this The resulting cumulative SHE profiles can be interpreted method 5 permanent 300m line transects were setup in each ecologically. If the samples are taken not from one (4) group of the blocks. The transect in each group was slowly homogenous population but across a gradient or up a traversed at a uniform pace for 30 min from 8.30 to 11.30 stratigraphic section, breaks in the curve may be used to infer hours during good weather period (no heavy rain or strong discontinuities (e.g. bio zone boundaries). winds). Butterfly species were recorded around a radius of five meter from the observer covering either side, above and g. Species Accumulation Curve front. Species accumulation curve is an approach by plotting the All individuals were identified in the field using standard cumulative number of species collected against the sampling guides and field guide books [17, 26]. Identification and effort (sample unit). From the year 2013 the species classification of butterflies was done using these literatures [27- accumulation curve for the four sites sampled individually, 31]. increased from first to the fourth sampling though the number of new species added slowly. 2.3 Data analysis Data analyses were performed by PAST software Version h. PCA (Principle Component Analysis) and PCO 3.02 [32]. (Principle Coordinates Analysis) Principal components analysis (PCA) finds hypothetical a. Measurement of diversity variables (components) accounting for as much as possible of The type of diversity used here is α- diversity which is the the variance in your multivariate data [38, 39]. Principal diversity of species within a community or habitat. The coordinates analysis (PCO) is another ordination method, also diversity index was calculated by using this index [33]. known as Metric Multidimensional Scaling. Two variables Diversity index = H = – ∑Pi In Pi, where Pi = S / N were chosen based on higher variance and eigen value scale. S = number of individuals of one species Density was plotted as component 1 and frequency was N = total number of all individuals in the sample plotted on component 2. In = logarithm to base e 3. Results b. Measurement of species richness During this study 106 species of butterfly species under six Margalef’s index was used as a simple measure of species families were observed in the study area (Table 1). Our result richness [34]. shows that 53 genera were represented by only one species Margalef’s index = (S – 1) / In N and 22 genera were represented by more than one species.

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