Checklist and Comparison of Butterfly Species found in Zoological and Botanical Gardens , University of Nigeria , Nsukka , Enugu State , Nigeria

Butterflies are creatures of nature with great economic importance as pollinators and bio-indicators. This study provides checklist of butterfly species present in Zoological and Botanical gardens of University of Nigeria, Nsukka and was conducted for three Months. Butterflies were sampled twice a week between 7.00 -10.00am from May to July 2019; using sweep net along existing transects within the gardens. Noninvasive method was adopted, butterflies were captured, photographed and released. Photographed samples were identified to species level by cross matching with relevant keys. A total of 91 butterflies belonging to 16 species, 10 genera and 3 families were sampled. Alpha diversity test showed a significant difference (p<0.05) in terms of Relative Abundance, Diversity and Dominance of butterfly species between the two gardens. The Botanical garden had Relative Abundance of 63.73%, Dominance of 0.23 which was higher compared to Zoological garden which had 36.16% and 0.10; but these was contrary to species diversity where Zoological garden was more diverse (H1=2.48) than botanical garden (H1=1.82). The differences observed could be attributed to variations in vegetation composition.


INTRODUCTION
Butterflies are creature of nature with great economic importance as efficient pollinators and bio-indicators of the environment (Farzana and Fatima, 2013). They are one of the most taxonomically studied group of diurnal flying insects and belongs to the second largest order Lepidoptera of the phylum arthropod (Yarger et al., 2016). There are more than 28,000 species of butterflies distributed across the globe with about 80% found in the tropics (Larson et al., 2001). As pollinators, they increase plants diversity, crop production, seeds and fruits; therefore, they indirectly sustain the survival of other flora and fauna in the ecosystem (Maheshwari, 2003). As bio-indicators, they indicate the health status of an environment and also serve as surrogates for whole biodiversity (Bonebrake and Sorto, 2009). Butterflies wide geographical distribution, ease of sampling and quick response to environmental changes qualifies them as good candidate for bioindicator therefore, their estimation within a given ecosystem is necessary for biological assessment of the ecosystem (Farzana and Fatima, 2013). This work provided a checklist of butterfly species present in the study area.

Study area
This study was carried out in both Zoological and Botanical gardens of the University of Nigeria, Nsukka Campus. The Zoological garden which was fenced with wire covered an area of 161,700m 2 (10,500m × 15,400m) has a coordinate of 6˚51᾽57.79῍N and 7˚24᾽40.63῍E, elevation of 397.154m above sea level. It harbors wild animals such as Monkeys (Chlorocebus pygerythrus), Chimpanzee (Pan troglodytes), Alligator (Alligator mississippiensis), Crocodile (Crocodylus niloticus), land tortoise (Geochelone elegans) and Python (Python sebae) all caged. It served as external laboratory for research for the students of Department of Zoology and Environmental Biology and also as recreational park for relaxation and frequently visited by secondary school and higher institution students for excursion. Species of trees such as Mango, Palm trees and some ornamental flowers were identified within the garden. It as a natural footpath created by visitors and workers in the garden. The Botanical garden is separated from the Zoological garden by a wire gauze, both gardens are adjacent each other. The Botanical garden covered an area of 80,850000m 2 (5250m × 15400m), located on a coordinate of 6˚51᾽56.29῍N, 7˚24᾽43.2῍E and elevation of 391.67m and made up majorly of ornamental plants.

Sampling procedure and identification
Butterflies were sampled twice a week during the morning hours (7.00-10.00 am) using sweep net of metal handle 121cm, circular mouth of 76cm, diameter 26cm and depth 64cm along existing transects not less than 100m within the gardens. Non-invasive method was adopted; each butterfly caught was photographed with camera (Samsung NX 50-200mm f/ 4.0-5.6 OIS Zoom camera lens) and released back into the garden. The photographed samples were used for identification to species level by cross matching with relevant keys at the crop protection Department, Entomology laboratory, Ahmadu Bello University, Zaria, Nigeria.

Statistical analysis
Data obtained were subjected to different analysis. Relative abundance of butterflies was calculated using the formula by Braimah and Popoola (2018). Shannon Wiener Diversity (H 1 ) and Simpson Dominance (D) were analysed using PAST3 software and t-Test was analysed using R statistical software package (386.3.3.2 version).

Relative abundance:
This was obtained by dividing the number of arthropods of a particular species with the total number of arthropods species sampled and multiplying by 100

Species compositions and Relative Abundance of Butterflies sampled between the two gardens.
A total of 91 individuals belonging to 16 species, 10 genera and 3 families were recorded during the study from both gardens (Table1). The Botanical garden has 58 individuals belonging to 10 species, 7 genera and 3 families while Zoological garden has 33 individuals belonging to 13 species, 10 genera and 3 families (Table 2). On the basis of species collected, Bicyclus safitza had the highest relative abundance (34.06), followed by Bicyclus auricruda (12.08), Precis oenone, (7.69), Acraea pharsalus, Acraea terpiscore, Eurema senegalensis, and Melanitis leda (n=5.49), Pseudopontia paradoxa (n=4.39), Acraea eponina and Bebearia oxione (3.29), Acraea uvuli, Euphaedra medon, and Papilio demoleus (2.19) while Hypolimus dubius, Papilio nireus and Papilio sosia had the least number and ranking (1.09) Table 2 and Figure 2. In-terms of family relative abundance Nymphalidae had the highesr (85.65) followed by Pieridae (9.98%) while Papilionidae was the least (4.39) Figure 3. The high relative abundance of Nymphalidae in this work agreed with the observation of Bhuyan et al., (2002), a preliminary study on the Butterflies of Regional Research Laboratory Campus, Jorhat, Assam. A total of 70 species of Butterflies belonging to 45 genera were recorded. Out of the five families, Nymphalidae was found to be dominant contributing 40 different species. Also, with the work of Ali et al., (2000), a study carried out in Zoo-Cum-Botanical garden, Guwahati, they recorded 72 species belonging to 43 genera with Nymphalidae family being dominant out of the five families. The work of Mozumdar et al., (2010), a study carried out in Trishna Wildlife Sanctuary, Tripura, Assam. A total of 1,005 individuals representing 59 species in 48 genera belonging to five families were recorded. Out of these, 23 species belonged to the family Nymphalidae and accounted for 38.98% of the total species and 45.20% of the total number of individuals.

Difference in the Relative Abundance of Butterfly species between the two gardens.
The t-Test showed a highly significant difference (P<0.001) in the Relative abundance of butterfly species between the two gardens. The Botanical garden had high relative abundance of 63.73% (n=58) compared to Zoological garden which had 36.16% (n=33) Figure 4. This may be attributed to the level of anthropogenic activities taken place in each garden. The Zoological garden has much human activities than the Botanical garden. The animals in the Zoological garden attracts excursionist, students and researchers visiting frequently compared to the Botanical garden. This difference observed in this work agrees with the observation of Nwosu and Iwu (2011), were they reported that rich butterfly species are found in protected areas with flowering and ornamental plants. The Botanical garden has much ornamental plants and less human activities as compared to the Zoological garden.

Species Diversity and Dominance between the two gardens.
Alpha Diversity test showed a highly significant difference (p<0.05) in terms of Shannon and Simpson indices between the two gardens. The Zoological garden was more diverse (H 1 =2.48) than Botanical garden (H 1 =1.82) Figure 5. While in terms of Dominance the Botanical garden was higher (D = 0.23) than the Zoological garden (D = 0.10) Figure 6. The high diversity of butterflies in the Zoological garden may be attributed to the presence of different species of fruiting trees such as Magnifera indica, Gmelina aborea and Elaeis guineensis identified during the study; unlike the botanical garden that is majorly made up of ornamental plants.

Conclusion
From the results, there was a significant difference in the relative abundance, diversities and dominance of butterfly species between the two gardens. The variations could arise as a result of different resources present in the different gardens required by different species of butterfly.