Raghavendra et al. The Journal of Basic and Applied Zoology (2020) 81:58 The Journal of Basic https://doi.org/10.1186/s41936-020-00192-w and Applied Zoology RESEARCH Open Access Biodiversity of butterflies in endosulfan- affected areas of Kerala, India K. N. Raghavendra, Kumar Arvind, G. K. Anushree and Tony Grace* Abstract Background: Butterflies are considered as bio-indicators of a healthy and diversified ecosystem. Endosulfan was sprayed indiscriminately in large plantations of Kasaragod district, Kerala which had caused serious threats to the ecosystem. In this study, we surveyed the butterflies for their abundance and diversity in three differentially endosulfan-affected areas viz., Enmakaje—highly affected area, Periye—moderately affected area, Padanakkad— unaffected area, carried out between the end of the monsoon season and the start of the winter season, lasting approximately 100 days. Seven variables viz., butterfly abundance (N), species richness (S), Simpson’s reciprocal index (D), the Shannon–Wiener index (H′), the exponential of the Shannon–Wiener index (expH′), Pielou’s evenness (J) and species evenness (D/S), related to species diversity were estimated, followed by the one-way ANOVA (F = 25.01, p < 0.001) and the Kruskal-Wallis test (H = 22.59, p < 0.001). Results: A population of three different butterfly assemblages comprised of 2300 butterflies which represented 61 species were encountered. Our results showed that Enmakaje displayed significantly lower butterfly diversity and abundance, compared to the other two communities. Conclusion: So far, this is the first study concerning the effect of endosulfan on the biodiversity of butterfly in the affected areas of Kasaragod, Kerala, India. This study may present an indirect assessment of the persisting effects of endosulfan in the affected areas, suggesting its long-term effects on the ecosystem. Keywords: Butterflies, Diversity, Ecosystem, Endosulfan, Kerala Background Being hydrophobic, endosulfan tends to get adsorbed into The extensive use of potentially harmful pesticides is still soil particles, resulting in persistence. The slow rate of done in many parts of the world. Endosulfan is a broad- degradation of endosulfan often results in the formation of spectrum organochlorine insecticide as well as an acaricide endosulfan sulfate (Kullman Seth & Matsumura, 1996). (Wang et al., 2012). Endosulfan (6,7,8,9,10,10-Hexachloro- Indiscriminately, it was sprayed aerially in cashew nut 1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodiox- plantations of Kasaragod District in Kerala, India. athiepine-3-oxide), comprises of two configurational iso- Kasaragod District is located in the south Indian state mers, alpha-endosulfan (64-67%), and beta-endosulfan of Kerala and has been a site for cashew cultivation by (29–32%), which acts as an effective GABA-gated chloride the plantation corporation of Kerala since 1970 (Fig. 1). channel antagonist and a Ca2+,Mg2+ ATPase inhibitor Cashew cultivation has been continued in the area, how- (Huang et al., 2019). Endosulfan kill insects by endocrine ever, only until 2011 endosulfan was aerially sprayed at disruption (Mnif et al., 2011). It is also a ubiquitous envir- an average height of 34 m above the tree canopy to onmental contaminant as its semi-volatile nature makes it protect the cashew trees from the tea mosquito bug resistant to degradation processes in the environment. (Ramesh & Vijayalakshmi, 2002; Misra & Joshi, 2018). Besides causing endless human sufferings, endosulfan * Correspondence: [email protected] being a broad-spectrum pesticide affected a diverse group Department of Genomic Science, Central University of Kerala, Periye, of the organism and resulted in a decline of about 40–70% Kasaragod, Kerala 671316, India © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Raghavendra et al. The Journal of Basic and Applied Zoology (2020) 81:58 Page 2 of 7 Fig. 1 Kasaragod map from Kerala State, India, showing (a) endosulfan-affected areas (Misra, 2015), (b) study areas: Enmakaje—highly affected area, Periye—moderately affected area, Padanakkad—unaffected area (Google map figure, n.d.). Note: Enmakaje and Periye are the places that lie under Enmakaje and Pullur-Periye panchayaths respectively diversity in the area (Mathew, 2012). As reported by the Specifically, we used the variation in the butterfly assem- local inhabitants, forest areas having rich wildlife (pre- blage as a proxy to measure the magnitude of disturb- dominantly birds and butterflies) as well as close to the ance associated with historical endosulfan applications plantation were affected. Consequently, a large butterfly and their persistence. We did pose two important ques- population had vanished, however, the current study tions: (1) Is endosulfan continuing to affect butterfly reports their recovery (Mathew, 2012). populations in the affected regions? (2) If so, how does it Butterflies are considered as bio-indicators of a healthy affect the compositional differences in butterflies? Con- ecosystem (Bouyer et al., 2007) and have an intimate re- sidering the duration since the last endosulfan-spray in lationship with plants. As endosulfan is persistent and 2011, our study helps in assessment and understanding butterflies have a close relationship with plants, they the existing diversity of butterflies in endosulfan-affected may be directly affected. An assessment of the Lepidop- areas. teran diversity, in particular butterflies, will help in un- derstanding the possible long-term effect of endosulfan Materials and methods on the diversity of insect populations. Study area Butterflies are important groups of model organisms and Three places in Kasaragod District were selected for the are extensively used in biological research including pest study based on certain criteria viz., the area of the cashew control, navigation, mimicry, embryology, evolutionary biol- nut plantation, the amount of endosulfan sprayed, and the ogy, population dynamics, genetics, and biodiversity conser- degree of biohazard it caused. The three places viz., Enma- vation. They have traceable taxonomy and are easily kaje (12°62′32.05′′N75°13′05.62′′ E), Periye (12°39′19.51′′ surveyed (Syaripuddin et al., 2015). The study of butterflies N75°08′82.36′′E), Padanakkad (12°25′76.24′′ N75°11′ over the years has provided unique data on an insect group 96.15′′ E) are one of the severely affected, moderately af- unmatched in timescale and geographical scale anywhere in fected, and unaffected area respectively (Fig. 1)(Govern- the world. This data is extremely important for research on ment of Kerala., 2003; Vijayan, 2011). To avoid the climatic change and biodiversity. likelihood of biases in the data due to the unlikeness of In the present study, we employed a survey method to vegetation among study sites including floral habitat, we investigate the effects of forest disturbance rooted to en- conducted prior checklist surveys in different locations. dosulfan spray, on butterfly diversity and abundance in The most commonly observed flowering plants in the endosulfan-affected areas of Kasaragod District. selected study sites were Lantana camara, Eupatorium Raghavendra et al. The Journal of Basic and Applied Zoology (2020) 81:58 Page 3 of 7 odoratum, Tridax procumbens, Clerodendrum infortuna- diversity profile curve and rarefaction curve using R tum,etc.Similartransectsofaround150mlengthinthe version 3.5.3. evergreen forest vegetation with shrubby habitat dominated by nectar-producing plants were selected for the survey Results from each place. Each transect (n = 3) was surveyed 12 times for a total of 36 surveys (Fig. 2). A total of 2300 butterflies of 61 Butterfly surveys species were encountered, Enmakaje was observed to Butterflies were counted along 3 Pollard-style transects display lower butterfly diversity and abundance com- (Pollard, 1977) with 12 replicates for each of the 3 places pared to the other two communities. Table 1 summa- by two observers. Surveys were conducted by walking rizes estimates for seven variables relating to butterfly 150 m long, 3 m wide transects at a constant pace (v =1 biodiversity: butterfly abundance (N), species richness ’ – km/h) while identifying butterflies within 1.5 m of each (S), Simpson s reciprocal index (D), the Shannon ′ – side and 3 m in front of the observer. Sampling was Wiener index (H ), the exponential of the Shannon ′ ’ ′ conducted weekly, between August (first week) 2018 to Wiener index (exp H ), Pielou s evenness (J ), and spe- November (first week) 2018, for 12 surveys/transect (36 cies evenness (D/S). We spotted a total of 37 species and total surveys). All observations were collected between 425 specimens in Enmakaje,