Spatio-temporal Diversity of Dung Beetles in Selected Locales of Sialkot, Punjab, Pakistan

Insects (Arthropoda: Insecta) are the largest and most diverse group within the animal kingdom. Pollinators, predators, parasitoids, herbivores, and decomposers are the most commonly studied functional groups, while Hymenoptera, Coleoptera, and Diptera are the most studied taxa (Noriega et al., 2018). Coleoptera contributes significantly in the ecosystem services i.e. pollinators, predators and decomposers. Dung beetles (Coleoptera: Scarabaeidae) are involved in decomposition of dung pats (Nadeau et al., 2015). The dung beetle fauna has been studied for ecosystem functioning, as indicators of anthropogenic disturbances and global change (Nichols et al., 2008; Nichols et al., 2009). Families of beetles associated with dung decomposition include Hydrophilidae, Histeridae, Staphylinidae, and Scarabaeidae and Geotrupidae. Hybosoridae and Trogidae have also been found more generally associated with the decomposition of carrion and cadavers to occur at dung (Nadeau et al., 2015). Nutrient recycling, soil turnover and seed dispersal are important ecological functions for ecosystem regulation (Hanski and Cambefort, 2014; Farias and Hernández, 2017). Dung beetles with over 7000 species have worldwide distribution (Silva, 2011; Vaz-de-Mello et al., 2001). Habitat loss, scarcity of food, cropping patterns, and agricultural practices are major causes of declining trend in dung beetle fauna (González-Maya and Mata-Lorenzen, 2008; Farias and Hernández, 2017). Environmental degradation has resulted in the changes in the spatio-temporal assemblages of species and may lead to possible local extinctions (Arellano et al., 2008; Gardner et al., 2008; Hernández and Vaz-de-Mello, 2009; Barlow et al., 2010; Farias and Hernández, 2017). Diversity and distribution of Dung beetle fauna reported from different parts of Pakistan include eleven species of the genus Onthophagus from Pakistan, fourteen species from Pothohar plateau during 2010-11 (Ali et al., 2015), fifty species from Azad Kashmir and Sindh province (Siddiqui et al., 2014), eighteen species from Gujrat, Bhimber, Mirpur and Kotli (Noureen et al., 2015) and twenty five species from different locales of district Sialkot during 2014-15 (Nasir et al., 2016) and fifteen species during 2015-2016 were recorded from Jhelum (Ghazanfar et al., 2017).

To create opportunities for the conservation of dung beetles, we need to improve our understanding of patterns of species diversity under different land-use practices and environmental pressures. This would provide opportunity to use these species assemblages as ecological indicators. The abundance of such species serve as a gauge to measure and interpret environmental change (Simmons and Ridsdill-Smith, 2011). Thus, extensive work on the diversity and distribution of dung beetles from different habitats of Pakistan need to be conducted. This study was undertaken to explore the diversity, distribution, community structure and relative abundance of dung beetles from selected locales of Sialkot.

The spatio-temporal diversity and distribution of dung beetle fauna was assessed during 2015-2016 from selected locales of Sialkot, Punjab, Pakistan (Figure 1).

Sialkot (32°29′33″ N, 74°31′52″ E), a district of the Punjab province situated at its north-east with hot and humid summer and cold winter (Nasir et al., 2016). Sampling of dung beetles was carried out from the selected locales i.e. Malianwala, Kanbanwala, Ugoki, Dhidwali, Bambanwala, Phangat, Bhola Musa, Malkhanwala, Amrik-Pura, Faizan-Colony, Sherwani-Colony, and Mundeke.

Sampling was accomplished by collecting dung pats and dung heaps randomly at an interval of two weeks. Fresh cattle dung was collected in a bucket with lid. We also used pitfall traps baited with cattle dung to collect dung beetles. Pitfall traps were placed at interval of 150 m (Larsen and Forsyth, 2005) in a 500 m transect (De Andrade et al., 2011). At each site, four traps were placed at an equal distance of 50 m from the center of the square whereas fifth one was placed in the center (Larsen and Forsyth, 2005) and traps were left out for 72 hrs (Davis et al., 2001). Collection of beetles was carried out by homogenized method: dung pats and traps were drained into the bucket containing water and stirred with the stick. Dung beetles floated on the surface of homogenized mixture (Houston et al., 1982).

After collection specimens were preserved in 4% formalin and stored in small vials with proper labelling (Banerjee, 2014). Identification of specimens upto species level was accomplished by using identification keys (Arrow, 1931; Creedy and Mann, 2011; Tissiani et al., 2017, Balthasar, 1963).

Relative abundance of species was calculated to compare the abundance of beetle fauna. Shannon- Wiener, Berger–Parker, and alpha diversity indices were calculated by analyzing the data collected from pitfall traps (Magurran, 1988). Shannon-Wiener index (H′) measures the species diversity within the community of an ecosystem (Sagar and Sharma, 2012). The lowest value is zero (if only one species) and maximum when all species of the sample in consideration have even abundances (Sagar and Singh, 1999).

Maximum abundance was recorded in Mundeke whereas the least abundant site was Malkhanwala (Figure 2). O. excavatus and O. crassus were dominant in the pastures whereas G. bicallosus was most abundant in cropland areas. O. singhalensis and O. cinctus were the most common in roadside old dung piles. O. gazella and O. subopacus showed the higher abundance in grassy fields. O. excavatus was recorded from all sites and was the most abundant species (Figure 3).

Data recorded from the study area indicated the presence of 16 species belonging to eight genera, six tribes and two subfamilies (Scarabaeinae and Aphodinae) of the family Scarabaeidae.

Results indicated variations in the relative abundance of species in different tribes i.e. Onitini (59.97 %), Aphodiini (12.89 %), Gymnopleurini (11.24 %) Oniticellini (7.80 %) and Coprini (0.75 %). Onitis (56.22 %) represented by five species was the most abundant genus followed by Aphodius (12.89 %) and Onthophagus (7.35 %) showed significantly higher abundance as compared to other genera. The relative abundance of species showed that O. excavatus (27.29 %), G. bicallosus (11.24 %) and O. crassus (9.60 %) were the most abundant species whereas O. bonasus (0.15 %) and H. bucephalus (0.15 %) were the least abundant species (Table 1).

The specimens studied were divided into three functional associations. Out of sixteen species, 10 species were tunnelers (Paracoprid), 4 species were dwellers (Endocoprid) and 02 species were rollers (Telecoprid). Tunnelers were the leading group representing 62.5 % of the species composition on the basis of functional guild. Dwellers shared about 25 % of the recorded guilds whereas rollers were represented by only 12.5 % of the species recorded from all guilds (Figure 4).

A. contaminatus, A. fossor and C. indicus were recorded only in August and September whereas C. pithecius and C. platypus were noted in September only. O. gazella were recorded in July, August and September, however, O. castaneous and O. bonasus were not recorded in the month of May, June and August. O. excavatus, O. cinctus, G. bicallosus, O. singhalensis and O. crassus were recorded during May and June 2016 (Table 3).

We calculated the diversity indices for different sites which showed variations in taxa and values of various indices at different sites. Data recorded from different sites showed moderate to high species dominance (Simpson’s indexes between 0.77-0.86). Similarly, variations in the species richness (H: 1.712-2.14), evenness (e: 0.65-0.85), dominance (1-D: 0.77-0.89), Menhinick (0.97-1.76) and Margalef index (1.51-2.73) were recorded from different sites (Table 2).

There is dire need to protect and conserve species in the changing land type use, human interventions and the climate change. Biodiversity conservation practices in the changing world demands conserving native biota of a given region (Chazdon et al., 2009). Our study attempts to understand variations in the population structure of

Table 1: Dung beetles (Scarabaeidae; Scarabaeinae) recorded from Sialkot, Punjab, Pakistan during 2016.

Table 2: Species diversity dominance, evenness recorded from different sites during 2016.

dung beetles in sub-agricultural landscapes. Our study has great significance considering that the dung beetles were included on the Red List of Threatened Species and information on the status and tendency of populations of 80 percent of the species in this list is unknown (Barretto et al., 2018).

The species reported in our study belonged to subfamilies Scarabaeinae and Aphodiinae. Genus Aphodius has been reported from the croplands with relatively higher abundance at different sites. Earlier studies noted that Scarabaeinae was dominant subfamily recorded from all habitats with Aphodius as most abundant species (Noureen et al., 2015). We collected majority of the beetles during the warmer months (May-September). In an earlier study conducted during (May-September), the variations in the dung beetle distribution has been associated with the temperature (Price, 2004). Results indicated that dung beetle assemblages in the selected locales of Sialkot during May-September, 2016 have shown the association of diversity (species richness, dominance and evenness) mainly with the grazing opportunities for the cattle and availability of cattle dung. Similar observations were recorded in an earlier study concluding that the biodiversity mainly depends upon richness of vegetation (Aslam, 2009). Similar results were reported previously

Table 3: Monthwise species distribution at different sites of district Sialkot during 2016.

which documented dung beetle faunal status and factors responsible for variations in the population dynamics include vegetation and cattle dung (Siddiqui et al., 2014; Zubair and Ratcliffe, 2015; Noureen et al., 2015). We recorded overall trend of decrease in species dominance, richness and abundance at sites where anthropogenic activities were more pronounced than others i.e. Malkhanwala, Amrik Pura and Faizan Colony. At these sites, more anthropogenic interventions were observed as compared to other sites. Dung beetle communities are closely associated with habitats characteristics and variations in the environmental conditions alters species structure. It was observed that animals were restricted in yards and movement of cattle was not frequent at these sites. Type of soil with variable moisture may have also influenced in the activity of beetles. Similarly, effect of other abiotic factors in addition to abundance of mammals may explain the variations in species structure and abundance (Nichols et al., 2009).

The different indices applied on the data suggested that variations in dung beetle assemblages at different sites existed. These values of diversity indices reflected that local variations in the vegetation cover and associated cattle resulted in the pattern of distribution of communities. Shannon-Wiener diversity index considers both the richness and evenness of species. Whereas evenness is a measure of the relative abundance of different species making up the richness of an area and expresses evenly distribution of the individuals among different species (Leinster and Cobbold, 2012). Referring to Magurran (1988), different diversity indices have advantages and disadvantages i.e. Margalef index also had a good discriminant ability but weighted towards species richness whereas Shannon–Wiener index was influenced more by richness and less by evenness than Simpson index which heavily weighted towards the most abundant species in the sample (Yeom and Kim, 2011). The Berger–Parker index showed the almost same character of advantages and disadvantages (Magurran, 1988, 2004). The Barger-Parker and Simpson’s dominance indices and Margalef’s diversity index showed little variations in the species diversity of the dung beetle fauna which may be attributed to the similarity in the vegetation type and quality of environment. In other guild structure studies, demonstrated that tunnelers dominated over dwellers and rollers in selected habitat (Vinod and Sabu, 2007; Sabu et al., 2006). The abundance of tunnelers in the area may be associated with the availability fresh dung pats of grazing animals. Herbivore dung and clay loam soil type (Hanski and Cambefort, 2014). Conservation through protected areas deems significantly important strategy but not grossly adequate (Rodrigues et al., 2004). The conservation strategies to be developed and implemented successfully, scientists need to know how different the impact anthropogenic activities on native biota and associated ecological and evolutionary processes (Gardner et al., 2008; Chazdon et al., 2009).

The study was undertaken to explore the diversity of dung beetles in the agriculture dominated rural landscapes. Sixteen species belonging to different feeding guilds were recorded. Paracoprid were dominant species with variations in the abundance. Onitis, Aphodius and Onthophagus were the most dominant genera whereas O. excavatus and O. crassus were the dominant species. Spatiotemporal distribution indicated that dung beetle assemblages varies greatly during different months within the season. Pastures with frequent cattle movement and low anthropogenic activities inhabit greater diversity and abundance as compared to farmlands with intensive agriculture. The results emphasize on the detailed surveys and studies on the introduction of dung beetle species in agricultural landscapes with respect to functional guilds and climatic variations.

The authors declare that there are no potential conflicts of interest associated with this research.