Introduction

An ecosystem is a community consisting of both living and non-living components that are present in the environment. Biodiversity includes all sorts of natural elements, such as wild and cultivated animals and plants. Moreover, it also has many aspects of nature variabilities ranging from molecular to the individual level (Gaston and Spicer 1998). Insects are one of the largest group of animals which are enormously significant for the environment which plays a vital part for the conservation of the ecosystem, improve health of the ecosystem, and the critical component for food web in both terrestrial and aquatic ecosystems (Kevan 2002; Shuriin 2005). Biodiversity is the multidimensional property of natural systems that quantify different challenges due to the multitude of indices. Indices seek to define the general characteristics of ecosystems that enable us to compare taxa, multiple regions, and trophic levels. Therefore, these are of vital significance for the conservation and monitoring of the environment (Magurran 2004; Leinster and Cobbold 2012; Morris et al. 2014).

About 125,000 species of the order Diptera have been described, including flies, mosquitoes, and midges (Mayhew et al. 2007). It is an influential group that plays a valuable role for the human and ecological system e.g. pollinators of different crops (Symank et al. 2008), and many of them are flowering plant species (Larson et al. 2001). Coleoptera is generally bio-control representative in nature, and their communication with the prey is of great importance (Oelbermann et al. 2008). They consist of customarily more than 360,000 depicted species. However, biological control is an environment-friendly alternative to hazardous and toxic insecticides, which are frequently applied to protect the plants (Bellows 2001). They are of great importance in pest control (Brown et al. 2010). Lepidoptera includes 157,424 described species, including butterflies and moths (Nieukerken et al. 2011). Butterflies are eminent taxonomically and ecologically, regarded as an excellent indicator of the ecosystem (Mihoci et al. 2011). Butterflies have cultural, financial, artistic values, and delicate to fractional deviation (Tiple 2011). They deliver significant model systems for scientific quarries and have a genuine impact on individuals as agricultural pests and predators (Wagner 2001; Roe et al. 2009). Hymenoptera consists of more than 115,000 defined species and covers nearly 10% of the species diversity (Sharrkey 2007). Sawflies, ants, wasps, and bees are dominant groups in this order, and they affect agriculture by various roles such as pollinators, parasitoids, pests, and predators (Michener 2000; Wilson 2006).

Insect diversity is directly and indirectly affected by natural enemies (predator and parasites), population dynamics, plant diversity, density, family size, habitat structural complexity, and environmental factors (Fernandes et al. 1994; Schoonhoven et al. 1998). The landscape features are well known that influence the community and the population ecology of species. The isolation of habitat fragments (Collinge 2000), patch area (Kruess and Tscharntke 2000), patch quality (Kuussaari et al. 2000; Hanski and Singer 2001), the ratio of habitat edge to the interior (Radeloff et al. 2000), and diversity of patch and seasons (Varchola and Dunn 2001; Braman et al. 2000); all these factors contribute to determining the richness and abundance of insects in a particular habitat. Landscape structure and habitat fragmentation influence the occurrence of arthropod communities (Gibbs and Stanton 2001).

Agriculture is extending nowadays, which provides more food by increasing the productivity of farms (Haberl et al. 2004). It includes a significant part of GDP (Idrees et al. 2020). Orchards are complex ecosystems in which plants have adjacent associations with different living constituents. Consequently, the fundamental modification in the community of plant has an impact on the population of arthropod. Citrus is an essential group of fruit crops, with extremely nutritious fruits (Hussain et al. 2004) having vitamin C and minerals (Supraditareporn and Pinthong 2007). The area of cultivation and fruit production of sweet orange and Kinnow are very significant in Pakistan.

Nevertheless, on earth, the most productive ecosystems are Wetlands. They are considered “the kidneys of the landscape” and “biological supermarkets” (Barbier et al. 1997). Wetlands maintain the ecological processes that provide a healthy ecosystem by regulating climate (Brander and Schuyt 2010). This kind of studies conducted to increase the knowledge about the faunal composition in different habitats/landscapes and to describe the importance of biodiversity. The purpose of the current study was to address the diversity indices of insects, their abundance in a particular habitat, and the ecological effect on diversity and abundance in different habitats.

Materials and methods

Study area

The study was conducted at the University of Agriculture Faisalabad (Punjab), Pakistan. Faisalabad is located at height (604 ft) a.s.l having latitude 30° − 31.5 o N and 73° − 74o E. It enclosed on East by Sheikhupura and Sahiwal, on West Jhung, North Chiniot, and South by Sahiwal and Toba Tek Singh (GOP 2015).

Sample collection and identification

The fauna was collected from the Agro-farms, citrus orchards, and around the pond areas (Eight Ponds) monthly from January 2018 to December 2018 (One-Year) for two hours. The insects (specimens) were obtained by succeeding methods: sweep net, direct handpicking, and Forceps.

In addition to these, the temperature and humidity of the study area were also noted as per objective. The collected specimens were preserved in jars containing 30:70% glycerin and alcohol solution. Besides these, collected samples were brought to the Biodiversity Laboratory, Department of Zoology, Wildlife and Fisheries, University of Agriculture, Faisalabad. Then the glass vials were prepared with a 30:70% glycerin and alcohol solution. After separation, collected specimens were stored in glass vials for further identification. Identification was made with the taxonomic literature help (morphological based traits) (Borror and DeLong 2005; Triplehorn and Johnson 2005), stereomicroscope (to elaborate the distinctive characteristics), and magnifying glass lens.

Statistical analysis

Subsequently, all the observed specimens (insects) were explicitly organized in the table by their morphological and taxonomic types e.g. order, family, genus, and species. For the determination of numerous features of diversity, Diversity (H), Evenness, Richness, and Dominance were calculated by given parameters/methods of Shannon (1948) and Magurran (1988). Pearson correlation was used to find the impact of abiotic factors (Temperature and Humidity) on the diversity and abundance of fauna.

For obtaining information about different diversity descriptors (number of rare species, singletons, doubletons, Shannon-weaver, and Simpson diversity indices) and richness estimators (Chao 2, Jacknifer 1 and Bootstrap), we used the Estimates v software. 9.1 (Colwell 2013). We built species accumulation curves for different habitats, plotting the cumulative number of insect species by the number of samples. We have used a Kruskall-Wallis test to assess whether the average number of insects recorded in the samples according to the habitats studied.

To evaluate a difference in the composition of insect assemblies according to habitat, we used Permutational Analysis of Variance (PERMANOVA). We used a non-metric multidimensional scaling (NMDS) to illustrate the relationship between the variables, using the Jaccard similarity index as the association measure. For this, we considered the presence or absence of each species in the sampling points. The statistical analyses were performed using the software PAST version 4.02 (Hammer et al. 2001) and R version 3.6.1 (R Core Team 2019), the package “vegan” (Oksanen et al. 2019), and Microsoft Office 365. All tests were analyzed at the level of significance α = 0.05.

Results

Overall, 3921 individuals/specimens were recorded during the whole study period. Maximum relative abundance was recorded from Agro-farms (1704), followed by pond areas (1214) and citrus orchards (1003) (Fig. 1). In the pattern of diversity, four orders from each habitat, (42, 49, 41) families and (84, 99, 86) species were recorded from Agro-farms, citrus orchards, and pond areas, respectively (Fig. 2A). The maximum population of Coleoptera (44.41%) was recorded from Agro-farms, while Lepidoptera (46.85%) was recorded higher from citrus orchards. In pond areas, the Coleoptera order was recorded dominant (36.43%) (Fig. 2B).

Fig. 1
figure 1

Abundance of fauna from different habitats

Full size image
Fig. 2
figure 2

(A) Taxa composition of insects among different habitats (B) Abundance of different insect’s orders with regard to their habitat

Full size image

Diversity (Hʹ) was recorded maximum (3.832) from citrus orchards as compared to the ponds (3.675) and Agro-farms (3.649); whereas, Evenness was recorded dominant from citrus orchards (0.4664) and least from Agro-farms (0.4578). After that, dominance was verified maximum from the ponds (0.0422) and lowest from citrus orchards (0.0299). Whereas, Margalef richness (R) was recorded maximum in citrus orchards (14.18) as compared to the pond areas (11.97) and Agro-farms (11.15). Other analyzed diversity factors are shown in Table 1.

Table 1 Diversity indices of various habitats
Full size table

Both temperature and humidity had a strong influence on insect diversity. In summer months, the temperature was noted maximum, which affected the diversity and abundance of fauna while the average temperature season favored the richness of insects. Humidity also forced a positive influence on diversity; data showed that a decrease in the humidity level population of insects was decreased (Fig. 3). The temperature significantly and positively correlated (p < 0.05), while the humidity correlated negatively with the diversity and abundance of the sampled insects (p < 0.01) from all the habitats (Table 2). For all habitats, the species accumulation curves did not reach a plateau and still in the growing phase. However, the curve referring to the ponds was the one that showed a significant tendency towards stability (Fig. 4). We found no difference in the average number of species according to the studied habitats (H = 3.79, df = 2, P = 0.149) (Fig. 5). However, we found a significant difference in species composition according to habitat (F2.33 = 1.868, P < 0.001). All habitats are different from each other (Fisher post hoc test, P < 0.05) (Fig. 6).

Fig. 3
figure 3

Association of temperature and humidity with the species richness of insects (A = Agro-Farms; C = Citrus Orchards; P = Ponds)

Full size image
Fig. 4
figure 4

Species accumulation curves for the different habitats studied

Full size image
Fig. 5
figure 5

Species richness according to different habitats studied

Full size image
Fig. 6
figure 6

Non-metric multidimensional scaling—NMDS of species composition according to different habitats studied

Full size image
Table 2 Correlation analysis of species with abiotic factors (Temperature, Humidity). *p < 0.05, **p < 0.01, n.s = no significant difference
Full size table

Discussion

Earth being supreme diverse, imperative habitat and species-rich community, has valuable diversity indices of flora and fauna (Khodashenas et al. 2012). Among them, macro-fauna has distinct diversity and local variations in different ecosystems, making the group much superior (Lavelle et al. 2006). The abundance and diversity of macro-fauna are also used as a tension-time index for soil profile (Palacios-Vargas et al. 2007). Biodiversity is considered very important in numerous ecosystem services, which depicts the current status of the area and can determine various factors (Xin et al. 2012; Moghimian and Kooch 2013). However, changes in land use, environment disintegration, supplement change, and stress may disturb the movement of energy and cycling of supplements (Wilsey and Potvin 2000). Determination of diversity, richness, Evenness, and abundance of fauna is required for ecological studies, habitat management, and conservation programs in any ecosystem (Nahmani et al. 2005).

Chiawo et al. (2017) studied the diversity of bees and floral resources in farmlands. A large abundance of bees was observed in Agro-farms, which described the plenty of floral resources in that habitat. The richness of floral resources is directly responsible for the richness of bee species. Wetlands are the main components of our climate, and these are in disturbance nowadays, ultimately affecting the associated fauna (Kevin 2008). The present study results described that temperature is the main factor in influencing insect diversity (Dunn et al. 2009; Diamond et al. 2012). Moreover, many scientists observed that climate change sturdily influenced the macro-faunal physiology through shifting the soil temperature and moisture (Booth et al. 2000; Brose et al. 2012; Lurgi et al. 2012). Hymenoptera exhibited prominent species dominance levels with variation in elevation (Sanders 2002; Burwell and Nakamura 2011), indicating that their distribution patterns were perhaps highly sensitive to overall temperature change (Deutsch et al. 2008; Del-Toro et al. 2015).

In the present study, Diptera was recorded maximum with a high richness of species. Order Diptera showed variations in their contact with humankind, habitat misuse, structure, and life habits. Economic losses occur due to flies, like fruit flies are responsible for damaging vegetables and fruits; due to this, it is considered as significant in agriculture (Thomas 2009). Abundance and species richness of different orders presented, unlike responses to structural connectivity of landscape and vegetation. Also, our findings were in line with studies indicating the positive response of syrphid species richness to flowers amount, vegetation, and grassland area (Kleijn and van Langevelde 2006; Meyer et al. 2009), which stress the importance of landscape composition for syrphid abundance (Alignier et al. 2014). Kathiresan and Bingham (2001) described that herbivorous insects could cause considerable damage to vegetations.

Agriculture has been the approach since a long time ago, and different studies have shown significant yield that upsurges in diverse cropping systems. Ecological studies proposed that more diverse plant communities are resilient to environmental perturbation and are resistant to a different environment (Alteiri and Nicholls 1999; Billeter et al. 2008). In the present work, diversity and abundance were recorded maximum from Agro-farms than all other habitats; the same inline context was found by the Rana et al. (2019); Naseem et al. (2020); Maqsood et al. (2020). Water bodies are tremendously helping in environmental sustainability as they support the faunal distribution in different ecosystems (Susila 2007; Balakrishnan et al. 2014; Majeed et al. 2019). The Coleoptera and Lepidoptera dominance in our study areas are indicated by the exceptionally higher abundance of some insects. They are considered the potential bioindicator of moist habitats as they prefer moist soil, litter, and rotting wood (Hall 2001; Sawada and Hirowatari 2002; Sorensson 2003).

Subsequently, from the complete data and discussion above, it is confirmed that our findings were similar to the literature those reported by previous researchers; however, at some point, deviations were observed due to differences in environmental conditions and skill power, documentation of data, and handling expertise.

Conclusions

Insects being a distinguished group on the earth, play a very crucial role in environmental management. In the present study, maximum abundance was found in the Agro-farms, and data also elaborated that Diptera was present in a significant number compared to other orders. Other orders which we found in less diversity and abundance suggested that environmental pressure and management techniques (primarily chemical) of food security affected them adversely. The ecological variables also subjected a substantial impact on the faunal diversity. Results might be beneficial in the management strategies of the biological control of fauna and conservation purposes. Future studies should be done with more and different sampling and planning approaches to elaborate insect fauna in particular habitats. Though it will also be endorsed for future research of biodiversity in different habitats to enhance the knowledge of this large group, that is still unknown.