Abstract
A study to find out the diversity of butterflies at the Indian Institute of Forest Management (IIFM), Bhopal, was carried out over a period of six months from October 2013 to March 2014. A total of 55 butterfly species belonging to 5 families, namely, Hesperiidae (7 species), Papilionidae (4 species), Pieridae (10 species), Lycaenidae (13 species), and Nymphalidae (21 species), were recorded (with photographic record) during the study from three different habitats of campus: open scrub, dry deciduous, and urbanized habitat. Shannon diversity indices and Pielou’s evenness index were calculated for all the habitats. Shannon index was found to be highest for open scrub (3.76). Out of 54 species, Eurema brigitta was the most dominant species followed by Eurema hecabe, Junonia lemonias, and Phalanta phalantha. Dominance of these species can be explained by the presence of their larval and host plants in the campus.
1. Introduction
Butterflies are one of the most conspicuous species of Earth’s biodiversity. Being extremely responsive to any changes in their environment, namely, temperature, humidity, light, and rainfall patterns [1–4], these insects are identified as useful bioindicators. They have different requirements for different habitat types for mating, breeding, and nectaring and are, thus, in sync with the diversity and quality of their habitats.
The present study aims to examine the diversity and distribution of butterflies across three different habitats, namely, dry deciduous, open scrub, and urbanized habitat. A checklist of butterfly species is also provided.
2. Materials and Methods
2.1. Study Area
The study was done in Indian Institute of Forest Management, Bhopal (23.208371°N and 77.384417°E), from July 2012 to March 2013. The location of campus, built on a hill at an elevation of about 556 m and surrounded by water on three sides, along with the wide range of climatic conditions that it passes through brings in diverse structure of habitats. The major types of vegetation included grasslands, open scrub forest, and dry deciduous forest and bamboo groves. The study was conducted in 12 transects (each approximately 300 to 500 m long) covering an area of 93-hectare campus.
For our study, transects were divided into three habitats according to general landscape attributes and vegetation present there. The chief habitat types were as follows: (1) open scrub, (2) dry deciduous, and (3) urbanized habitat.
2.2. Butterfly Survey
The survey of butterfly was done using Pollard walk method [5, 6] from 8 am to 10 am. The butterflies were observed within 2.5 meters to the left and right side and five meters in front of the observer. Butterflies were observed, captured, identified, and released immediately at the spot of capture. A butterfly net was used for this purpose. Many of the species were photographed in the wild. The dead specimens, many of them not in very good condition, were kept in butterfly collection boxes. Collecting live specimens was avoided during the study.
2.3. Data Analysis
(A) Shannon Index . Species diversity was calculated using the Shannon Index [8]: Here, is the proportion of the th species in the total sample. The number of species (species richness) in the community and their evenness in abundance (or equitability) are the two parameters that define .
(B) Pielou’s Evenness Index (Equitability) or . The species evenness is the proportion of individuals among the species. Evenness of species indicates their relative abundance on site [8, 9]: Here, is the number of species present in the site.
3. Results
A total of 55 butterfly species with a total of 815 individuals belonging to 5 families were recorded (with photographic record) during the study. The butterfly list along with their abundance in different habitats is given in Table 1. There are 8 species with lowest individual number having abundance less than 5 in all the three habitats. The three most abundant species are Eurema brigitta (with 48 individuals) followed by Eurema hecabe (with 45 individuals) and Junonia lemonias (with 34 individuals). The greatest number of all these three species occurred in open scrub. Out of 55 species, 52 were found in open scrub followed by 49 species in dry deciduous habitat and then 44 species in urbanized habitat. A total of 815 individuals were recorded from the campus with highest abundance in open scrub () followed by dry deciduous habitat () and urbanized habitat (). Out of the five families of butterflies, Nymphalidae were the most commonly recorded, accounting for 38% () of total species recorded followed by Lycaenidae 23% (), Pieridae 10% (), and Hesperiidae 12% () of total species and minimum was recorded for Papilionidae 7% ().
Figure 1 shows that proportion of rare species tends to increase from open scrub to dry deciduous to urbanized habitat. The proportion of uncommon species is similar in open scrub and dry deciduous environment while it tends to decrease in urbanized structure. The proportion of common species, on the other hand, indicates a decreasing trend from open scrub to dry deciduous to urbanized environment.
The diversity of butterfly species in three different habitat types in IIFM is presented in Table 2. The open scrub has the greatest species number with 52 species while urbanized habitat ranks lowest with 44 species. The same order follows for abundance and diversity index with highest diversity index for open scrub and least for urbanized habitat and greatest individual numbers for open scrub and least for urbanized environment. The greatest species number of open scrub habitat leads to the high diversity index although it has a lower evenness index than dry deciduous habitat. The evenness index is almost similar in the entire three habitats with the index being highest in dry deciduous habitat where there is not any dominating species with high individual number.
4. Discussion
Fifty-five species of butterflies were documented during the survey. Open scrub, the least disturbed, was found to have the highest species richness followed by dry deciduous habitat and the lowest in urbanized habitat, the most disturbed. These results can be attributed to the presence of host and larval plant species, whose occurrence impacts distribution of butterflies [10]. There are many studies that have shown higher butterfly diversity in disturbed habitat or forest gaps than that in dense forest or closed canopy [11–14]. This study, therefore, shows some sort of contradictory results which might be due to different levels of disturbance among these habitats, more in open scrub in terms of human interference in the form of fuel wood gathering, cattle grazing, forest fire, and so forth, but less in urbanized habitat where there are well maintained gardens. These human interferences result in more gaps, edges which provide more light and space, and diversity in plant structure to support more butterfly species than natural forest [3, 13, 15]. The correlation of disturbance and occurrence of butterflies is attributed to the emergence of secondary vegetation like Lantana camera, Eupatorium odoratum, and so forth, which are good food sources for many butterfly species [14].
One important aspect of study is the statistics of common species between different habitats which indicates the beta diversity and how different (or similar) these habitats are in terms of the variety and abundance of species found in them. The open scrub and dry deciduous habitat showed highest number of shared species (47 species), as these areas are relatively more rich in food resources in terms of nectars for butterflies. Species community structure was different among habitats, but rather similar in the open scrub and dry deciduous habitat. Many species of butterflies depend on remnant vegetation or secondary forest for survival, especially in urban areas [15, 16]. So for the conservation of species in human dominated landscape, any institutional campus maintaining high plant diversity and different types of habitats is a good option.
Conflict of Interests
The author declares that there is no conflict of interests regarding the publication of this paper.