Spatial and temporal dimensions of butterfly species diversity in Jahangirnagar University campus and its suburbs , Bangladesh

Survey was conducted in four different areas viz. Jahanginagar University Campus, Gerua, Nabinagar and Chandra of Bangladesh from October 2012 to September 2013. A total of 100 species of butterflies under 9 families were identified. The maximum number of butterflies (31 species) was recorded under the family Lycaenidae followed by Nymphalidae (17 species), Pieridae (16 species), Hesperiidae (15 species), Satyridae (7 species), Papilionidae (7 species), Danaidae (5 species) and 1 species to each family of Acraediae and Amathusiidae. Species diversity was higher from summer to early monsoon and declined in late winter. Out of four areas, the highest number of butterfly was recorded at Jahangirnagar University campus followed by Gerua, Nabinagar and the lowest at Chandra. Out of 100 species, 7 were very common, 12 were common, 17 were rare, 64 were very rare. Dusky Part Wing (Psolos fuligo Mabille, 1876) under the family Hesperiidae was recorded for the first time in Bangladesh.


INTRODUCTION
Butterfly is one of the most wonderful and fascinating smaller creatures on earth.It has been increasingly recognized that butterflies are important for ecological and conservation monitoring because of its strong sensitivity to any changes of climatic conditions as well as seasonal and ecological changes (Kunte 1997;Houlahan et al., 2000;Mac Nally et al., 2004;Stuart et al., 2004).Adult butterflies function as vital plant pollinators in the environment causing pollination to more than 50 economically important plant crops (Borges et al., 2003, Rajagopal et al., 2011).However, it is a matter of regret that they are not taken into account under conservation efforts at broad way.

MATERIALS AND METHOD
Study sites: The study areas are geographically situated in central part of Bangladesh under Dhaka and Gazipur district.The study sites were selected depending on their vegetation characteristics and human interferences.The temperature was highest in April (36.3°C) and lowest in January (7.7°C).The total rainfall during the study period was 1217 mm and the mean monthly humidity was 82.07 %.Description of the study sites are given below: Jahangirnagar University campus (J): The campus of Jahangirnagar University is an undeclared sanctuary.Geographically the campus is at 23°5243.89'N latitude and 90°1617.10'E longitude, 32 km north-west from Dhaka City which includes about 280 hectors of area and it is about 6 meter high from mean sea level (Fig. 1).There are many woodlands, grasslands, garden, vegetable garden, rice field and bushes which are the habitat of many insects and wildlife including butterflies.All of these plants are very important for butterfly as larval host plant and nectar plants.

Gerua (G):
It (23°5202.61'N latitude and 90°1247.70'E longitude) is adjacent to Jahangirnagar University campus (Fig: 1).It is also enriched with reddish and yellowish soil with large amount of iron, aluminum and calcium.From the month of June to August, east side of gerua bazaar (crop field site) covered with rainwater.Gerua consists of some cultivated lands, homestead vegetation and bushes.

Nabinagar (National Martyr's Monument and Kurgao area) (N):
Geographically it (23°5443.87'N latitude and 90°1513.05'E longitude) is closed to Jahangirnagar University campus (Fig. 1).It is enriched with red soil.Nabinagar is most human produced disturbed area.This area is bounded by Savar Cantonment Golf course on south and Jahangirnagar University campus on south east, Chandra-Nabinagr road on north-east , Ganakbari on north, Gono Shastha and Bangshi river on west.

Chandra (Sal Forest Area) (C):
Chandra, the moist deciduous Sal (Shorea robusta) forest is distributed at the Kaliakur Upazila in Gazipur district.Geographically it (24°0300.66'N latitude and 90°1414.93'E longitude) is closed to Nabinagar area (Fig. 1).It is characterized by high, undulated land surface with red soil.Sal plants were more common in this area, but at present these natural trees are replaced by exotic plant species (Acacia sp.).Chandra area is divided into eastern and western part by Nabinagar -Chandra road.BKSP (Bangladesh Krira Shikkha Proothistan), Nandan Park and EPZ (export processing zone) situated on south of this area.
Sampling methods: Butterflies were collected from morning 8:30 am to evening 5:00 pm during October 2012 to September 2013.However, counting days were changed during unfavorable weather condition.Similar transect-line was set up at each site.
Collection: Butterflies were collected using a hand-held sweeping net and placed in killing jar.Chloroform was used as killing agent.After killing, they were taken into triangular paper envelope to give a perfect using shape.At last, specimens were taken in laboratory at Department of Zoology, Jahangirnagar University for further confirmation of identification and preservation.
For assessing butterfly status, the observed butterflies species were grouped into four categories to indicate the status of assessment namely : Very common (VC) : presence of 35 to 50 butterfly per month , Common (C) : presence of 20 to 35 butterfly per month , Rare (R) : presence of 10 to 20 butterfly per month and Very Rare (VR) : presence of 1 to 10 butterfly per month.

RESULTS AND DISCUSSION
During the period of study, a total of 100 species of butterflies under 9 families were recorded.Among them, 17 species belonged to the family Nymphalidae, 16 species to Pieridae, 31 Species to Lycaenidae, 7 species to Satyridae, 7 species to Papilionidae, 5 species to Danaidae, 15 species to Hesperiidae and 1 species to each family of Acraediae and Amathusidae in JU campus, Gerua, Nabinagar and Chandra (Table 1, Fig. 2).Out of 100 identified species, 1 species, Dusky Part Wing (Psolos fuligo Mabille, 1876) under the family Hesperiidae was newly recorded species in Bangladesh (Plate 1).This species found at bushes and preferred shady areas.Besides Bangladesh, this species is also found in India, Laos, Malaysia, Philippines, Singapore, Thailand and Vietnam (Choudhury & Hossain, 2013).
In JU campus a total of 98 species (except Rapala iarbus and Arhopala amantes) under 9 families were recorded (Table 1).On the other hand, 71 species of butterflies under 8 families, 69 species under 8 families and 68 species under 8 families were recorded from Gerua, Nabinagar and Chandra respectively, (Table 1 and 2).
Out of 100 species, 27 were found throughout the year in all study areas and the species were Junonia atlites, Junonia almana, Phalanta phalantha, Cethosia cyane, Neptis hylas, Leptosia nina, Eurema hecabe, Delias eucharis, Castalius rosimon rosimon, Prosotas dubiosa, Rapala manea, Chilades laius laius, Zizula hylax, Remelana jangala, Zizina otis sangara, Zizzeria maha, Melanitis leda, Mycaelesis perseus blasius, Mycaelesis perseus, Elymnias hypermnestra, Mycaelesis mineus, Graphium agamemnon, Papilio polytes, Graphium doson, Papilio demolius, Parnara guttata, Telicota ancilla bambusae and the rest of the other species were season specific (Table 1).Butterflies did not occur evenly throughout the year and species abundance was gradually increased in the month of November, 2012.On the other hand the highest species diversity documented during March to April, 2013 whereas the lowest species diversity in January, 2013 (Table 3).Previously, an investigation from JU campus reported 51 species, where 21 species were identified as new records from Bangladesh (Hossain et al., 2003).Among 51 species, 39 were similar compared with the present study.Besides, Razzak et al. (2004) reported 80 species of butterfly belonging to 10 families from JU Campus of which 36 species were new records from Bangladesh.Among 80 species reported by Razzak, 64 species were similar to the present finding.Shefa & Hossain (2010) reported 4 more new species from Bangladesh in a survey from JU Campus of which Taracus nara, Junonia orithya and Zizula hylax were similar to the present finding (Table 1).On the other hand, a total of 89 species under 10 families were recorded from JU Campus by Asaduzzaman (2011) of which 70 species were similar to the present findings (Table 1).Islam et al. (2011) conducted an investigation in four different areas of Savar as, Krishnopur, AERE (Atomic Energy Research Establishment), Horters (part of JU Campus) and Rajalak Farm those were not overlapped with the selected areas of present investigation.They identified 158 species of butterfly under 10 families.Out of 158 species, 74 species were similar to the present findings (Table 1).They showed Delias hyparete, Mycaelesis mineus, Acraia viole and Neptis jumbah as very common (VC) species where these species were very rare (VR) compared to present findings (Table : 1).
On the other hand, Islam et al. (2011) showed Neopithecops zalmora, Catopsilia pomona, Mycaelesis perseus as rare (R), but in present finding these species were common (C) (Table 1).Present record of 100 butterfly species in JU campus and its suburbs indicates that the diversity of butterfly has been increasing to greater extent.The JU campus is rich of its own diversity of vegetation types (Hossain et al., 1995).This diverse ecological habitat includes woodlands, climbers, vines, grasses, shrubs and herbs.The reason for increase of butterfly diversity in JU Campus might be due to its vegetation type (larval host plants and other vegetations for nectar and shelter of butterflies), soil condition, lake and favorable climate conditions (Hossain et al., 2003;Bashar et al., 2003;Razzak, et al., 2007;Tiple, 2009;Shefa & Hossain, 2010;Chowdhury & Hossain, 2013).In this present study, lowest number of butterfly species was recorded at Chandra (68 species) and highest number was recorded at JU Campus (98 species) (Table 2).Nabinagar and Chandra were more vulnerable to butterflies, because of the introduction of exotic plant species and monocultures (Nagy et al., 1998;Kocher, 2000;Marini-Filho et al., 2010;Majumder et al., 2013), contamination of soil, air and water quality by disposal of industrial waste and chemicals (Rima, 2014), human interference (Kocher & Williams, 2000).
Natural habitat selection of butterflies is directly related to the availability of preferred food plants for larvae and adults (Grossmueller & Lederhouse, 1987;Thomas, 1995).But it was observed in the present study that the natural plant habitat being converted with exotic plant species (Acacia sp) in Chandra (Sal forest) and monocultures that may be responsible for the poor species richness and diversity of butterfly (Nagy et al., 1998;Kocher, 2000;Marini-Filho et al., 2010;Majumder et al., 2013).Acacia sp. was the most dominant plants at Chandra (Sal Forest) and this exotic species was also observed at minimum level in JU Campus.Acacia sp. is threatening to native habitats by competing with indigenous vegetation and it is also responsible for the alteration of microbial soil functionalities and the early development of a native tree species (Boudiaf et. al., 2013).
Although Acacia plant has many more bad effects to environment but in the present investigation it was observed that Acacia auriculiformis (Akashmoni) also act as larval host plant of a butterfly, Common Acacia blue (Family: Lycaenidae) (Monwar Hossainpersonal communication).
The changes in the diversity of butterflies occur due to various causes.Short-term changes may occur due to variation in weather, whereas long term changes due to modification of habitat quality and availability of larval host plants (Kocher et al., 2000).Butterflies are highly season specific.During the adverse condition of weather, in late winter (December, 2012-January, 2013) low population of butterfly was maintained due to scarcity of water, drying of grasses and other nectar feeding plants, continuing cold weather and low moisture (Table 3).The optimum time for butterfly species richness was from March, 2013 to June, 2013) (Table 3).The reason for increase of diversity might be the availability of nectarine plants such as Ixora chinensis, Lantana camara, Curcuma sp., Ageratum conyzoides, Mykania sp and so on.Those are good food sources of adult butterflies in early winter and the availability of larval host plants like Citrus sp, Madhuca indica, Mimusops elengi, Neolamarckia cadamba, Polyalthia longifolia, Mangifera indica, Artocarpus heterophyllus etc. in spring and summer as well as favorable weather conditions (Farjana Akter -personal observation).The availability of adult and larval food plants is the main biotic factor to retain butterfly diversity (Ruszczyk, 1986b).
The riches diversity of butterfly species indicates the good and healthy environment since butterfly acts as biotic indicators to any environmental change and habitat structure changes (Brown & Chippendable, 1974;Thomas, 2005;Gross et al., 2007).The presence of more herbaceous plants makes opportunity and support for most of the butterfly.Due to existing of various economic and ecological importance (good indicator of climatic change and pollinator), butterfly conservation is necessary.Therefore to save our flying beauty and to enrich the population of butterfly, awareness buildup among mass people is necessary along with concern authorities should take necessary measures at greater extent to maintain the sustainability of our ecosystem.

Table 1 . Status, abundance, occurrence and distribution of butterfly in JU campus and its suburbs
VC= Very common, C= Common, R=Rare, VR=Very rare; J=JU Campus, G=Gerua, N=Nabinagar, C=Chandra; * detailed in methods and materials