Arthropod Biodiversity in Agricultural, Horticultural and Silvicultural Ecosystems with Special Reference to Spiders (Araneae) in Mid-hills of Meghalaya, India


 Spiders are the Arthropod and belong to the Phylum: Arthropoda, Class: Arachnida, Order: Araneae. Their occurrence worldwide is about 30,000 species belonging to the 60 families. Totally 4023 arthropods were collected from Silvicultural, Horticultural and Agricultural ecosystem (Maize, Potato and Rice) which belonged to 14 orders and 85 Nos. of different families. Among the ecosystem maximum diversity found in Silvicultural followed by Horticultural and Agricultural ecosystem in terms of alpha diversity such as Shannon Wiener index Simpsons D, Species number, Margelef D, Equitability J, Berger Parker index, Maclntosch U, Brillouin level, Fisher Alpha, Q Statistic and beta diversity such as Whittaker Bw, Cody Bc, Routledge Br, Routledge Bi, Routledge Be and Wilson & Shmida Bt.


Introduction
Biological diversity is the first terminology used by biologist Lovejoy in the year 1890 to describe numbers of species. E. O. Wilson first used the term 'Biodiversity' in written form in the proceedings of U.S. Strategy Conference on Biological Diversity (1981) held on Washington D.C. (Swingland, 2001). Biodiversity can be measured in terms of genetic diversity and the identity and number of different types of species, assemblages of species, biotic communities, and biotic processes, and the amount (e.g., abundance, biomass, cover, rate) and structure of each. It can be observed and measured at any spatial scale ranging from microsites and habitat patches to the entire biosphere" (DeLong, 1996). Spiders utilize a wide range of strategies for capturing preys which makes them a 'model predator' by trapping the prey in sticky webs, lassoing with sticky balls, mimicking the prey to avoid detection and they mainly detect the prey by sensing vibrations, but in case of active hunters they possess acute vision. In natural habitat spiders also have many predators therefore they possess some defence mechanism to defend themselves; ability to blend with the environment as a form of camouflage, flick hairs at their enemies, webs which will trap the predators as well as prey and the venom which is the most powerful defence mechanism. In terrestrial ecosystem, they constitute the most abundant predator and consume large number of preys without damaging the plant, only feeding on insects, their larvae and eggs. In Tapioca plantation maximum diversity was found in predatory spider family Argiopidae (32.5%) followed by Aranidae (26.2%), Tetragnathidae, Lycosidae and Lynyphiidae. The most abundant spider was Neoscona theisi in the field due to plant architecture of tapioca plants. Large orb web weaver (Araneidae and Argiopidae) trapped large prey species of Orthopteran insects Hieroglypus feanian and Lepidoptera insects Scirphaga incertulas and Malanitis leda ismena, while Tetrangnatha maxillosa trapped small soft-bodied Dipteran insects Orseolia oryzae (74.6%) and Hemipteran insects Nephotettix virescens (25.4%). The cone web spiders capture N. virescens (60.7%) and other Orthopteran (39.3%) insect . The denominated spider group in orchard ecosystems areclubionid spiders (Clubiona pallidula, Clubiona phragmitis and Cheiracanthium mildei). Stripped lynx spider (Oxyopes salticus), green lynx spider (Peucetia viridans) and jumping spider (Phidippus audax) are the predatory spiders reported in cotton ecosystems which limits the pest flea hopper (Pseudatomoscellis seriatus), tarnished plant bug (Lygus lineolaris) and noctuids (Heliothis spp.). Clubionid species Cheiracanthium mildei and Cucurbitina opistographa are the predatory spider dominated in apple orchards and limits apple leaf miner (Phyllonorycter blancardella), Psylla mali, Anthonomus pomorum and apple mite (Bogya, 1999). Overall objective of research work is to enhance the scientific understanding of the silvicultural, horticultural and agricultural arthropod, with special reference on spider community, as a basis for an improved, conservation oriented management practices. Conservation of biodiversity without knowing its component is meaningless. In order to understand how to sustain biodiversity, we should be concerned about arthropods. The objectives of the study are: 1.1 Collection and identification of various arthropod fauna in agricultural, horticultural and silvicultural ecosystems.
1.2 To find out arthropod diversity, richness and abundance in agricultural, horticultural and silvicultural ecosystems.

Materials and methods
The investigation was carried out at Experimental farm of CPGSAS, CAU, Umiam during the time period 02 July, 2019 to 11 February, 2020. Weekly observation were taken from 1st standard meteorological week (SMW) i.e. 27 th SMW of July, 2018 onwards till 06 th SMW of February, 2019. The sample collection was done in 3 ecosystems and took an area about (10 × 10) m 2 , 100 m 2 Viz., Agricultural ecosystems (Maize, Zea mays L.; Potato, Solanum tuberosum L. and Rice, Oryza sativa L.), Horticultural (Citrus, Citrus limon L. and Turmeric, Curcuma longa L.) ecosystem and Silvicultural (Native forest dominated by Pine, Pinus insularis Endl. trees) ecosystem.

Sampling methods
Collection of arthropods was done through hand picking, using aspirators, sweep nets, Inverted umbrella, pitfall trap and rubbish trap. Both adults and larval/nymphal forms were collected and immature stages of the insects will be reared for emergence of adult for easier and proper identification. For carrying out arthropods collection, the plot was divided into 100 quadrats measuring 10 m × 10 m. Five such quadrats were chosen each at four corners and one in the middle. In each of the quadrats five pitfall traps were installed and the entire plot was covered during the sampling period.

Collection techniques
The collection of arthropod samples was done by standard protocol such as net sweeping, pitfall trapping, ground and aerial hand collection etc. which was used by Schuldt et al. (2008) and Kujur and Ekka (2016). Spiders and insects from rocks, logs, debris and bark of the trees were collected by hand picking and active searching. This method was used by Rajendran et al. (2017) for the collection of arachnids from orange orchards. For collection of ground dwelling arthropods pitfall traps were used which is buried in soil and filled with 4% formaldehyde solution or teepol for reduced surface tension and fixative and a total of 5-6 traps were placed 1m apart in an area of 100 m 2 Which was used by Bouseksou et al. (2015), Khan and Rather (2012) and Kujur and Ekka (2016).

Preservation of Arthropods
Spiders and insects were killed using chloroform and the specimens were preserved in 5 ml glass vials with 70 per cent ethyl alcohol (70 parts of 100 per cent alcohol + 30 parts of distilled water) which was used by Joseph and Premila (2016). Khan (2009) and Khan and Rather (2012) also followed the standard protocol for preserving the very small spider specimens and the juvenile spiders in Oudeman's fluid (85 parts of 70 per cent alcohol + 5 parts of glycerine + 8 parts of glacial acetic acid + 2 parts distilled water), the same protocol was followed for preservation of spiderlings.

Identification of Arthropods
The most common and important arthropod species were identified to the lowest possible taxon.

Alpha Diversity indices
Measures of diversity are frequently seen as indicators of the wellbeing of any ecosystem. They also serve as a measure of the species diversity in the ecosystem. The following indices were worked out basis of month wise to assess the diversity and distribution of arthropods in observed ecosystems. Species richness indices, Margalef's D, (Clifford and Stephenson, 1975), Fisher's alpha (Fisher et al., 1943), Shannon diversity index (Batten, 1976), Brillouin diversity index (Magurran, 1987), Q statistic (Kempton and Taylor, 1976), Species dominance indices, McIntosh index (McIntosh, 1967), Simpson's index (Simpson, 1949), Berger-parker diversity index (Berger and parker, 1970) and Evenness indices.

Beta diversity indices
Beta diversity measures measures two attributes, the number of distinct habitats within a region and the replacement of species by another between disjoint parts of the same habitat. All of the selected samples in the active data set will be used to calculate the indices. It is assumed that the samples are arranged in the data grid in their order of occurrence along the transect. The six indices calculated, which are described below are those considered by Wilson and Schmida (1984). All six required presence or absence of data. Following indices were evaluated Whittaker's measure (βw), Coby Bc and Routledge's R, I & E.

Arthropods
The collected samples belonged to 2 classes of arthropods Viz., Arachnida and hexapoda (Insecta). The experiment focuses especially on Arachnida and the diversity of class Arachnida is given in the Table 1 to 12. Totally 4023 arthropods were collected from silvicultural, horticultural and agricultural ecosystem which belonged to 14 orders and 85 Nos. of different families (Table 1). In familial level maximum diversity was found in class Insecta composed of 66 Nos. of family and 186 Nos. of genera and class Arachnida composed of 19 Nos. of family and 67 Nos. of genera (Table 2). In ordinal level maximum diversity was found in class Insecta composed of 13 Nos. of family and class Arachnida composed of 1 Nos. of family.
In potato ecosystem, a total of 103 Nos. individuals of Arachnids was collected which comprised with 5 Nos. of families under 10 Nos. of genus and 12 Nos. of species (Plate 4). The maximum diversity at generic level was found in the family Ganophosidae (3) followed by Salticidae (3), Zodariidae (2), Cheiracanthiidae (1) and Lycosidae (1). Maximum species was collected at the month of December to February. On the other hand maximum individuals were found in family Salticidae (35) followed by Ganophosidae (32), Lycosidae (19), and Zodariidae (14) and Cheiracanthiidae (3) (Fig. 5).
At rice ecosystems a total of 567 Nos. individuals of Arachnids was collected and comprises with 10 Nos.

Insecta
The present study was restricted to collection of major arthropods from 5 ecosystems Viz., silvicultural, horticultural, potato, maize and rice ecosystems. A total of 727 Nos. of samples collected belongings in the group Pterygota (Table 2). Among Pterygotes orders like Orthoptera, Dermeptera, Hemiptera, Odonata, Dictyoptera, Isoptera, Ephimeroptera and Phasmatodea were observed which belonged to division Exopterygota and orders like Coleoptera, Neuroptera, Diptera, Lepidoptera and Hymenoptera were belonged to the division Endopterygota. In the class insecta maximum familial diversity was found in silvicultural ecosystem followed by horticultural, rice and maize ecosystems. The maximum diversity was found in the order of Hemiptera (22 Nos. of families), the majority of individuals fall under the family Aphididae (50), Pyrrhocoridae (12), Nepidae (9), Pseudococcidae (8) and Coreidae (8) etc. The aquatic hemipteran was represented by the 2 families Nepidae (genus Ranatra and Lethocerus) and Belostomatidae (genus Belostoma).

In observed ecosystems
In observed ecosystems Shannon Wiener index was found maximum at species level in silvicultural ecosystem (3.409) followed by horticultural (3.332), rice (2.644), potato (2.193) and maize (2.091) ecosystem (Table   4). In whole sampling period the Shannon Wiener index in species level was ranged in silvicultural (

Species number
The species number was calculated based on ordinal level during the period from July, 2019 to February, 2020. In silvicultural ecosystem, araneofauna was found to be maximum in month of September (14) (Table 5).

Beta diversity indices at species, familial and ordinal level
In the current study of beta diversity indices, Whittaker Bw, Cody Bc, Routledge Br, Routledge Bi, Routledge Be and Wilson & Shmida Bt were used to compare the species composition of Arachnids communities in all the five ecosystems Viz. silvicultural, horticultural, maize, potato and rice ecosystem. Analysis based on Whittaker Bw at species level revealed that variation was highest in silvicultural ecosystem (1.170) followed by horticultural (1.000), rice (0.487), potato (0.343) and maize (0.128) ecosystem. Cody Bc index was found maximum in silvicultural ecosystem (77.500) followed by Horticulture (42.000), rice (11.000), maize (4.500) and potato (1.500) ecosystem. The trend of variation of beta indices at falilial and ordinal level is represented in the table 6.
In horticultural ecosystem, a total of 1010 Nos. individuals of silvicolous spider was collected which comprised of 13 Nos. of families under 40 Nos. of genus and 65 Nos. of species. The maximum diversity at generic level was found in the family Araneidae (8) followed by Ganophosidae (7), Salticidae (6), Lycosidae (4), Tetragnathidae (3), Theridiidae (3), Zodariidae (3), Thomisidae (2), Oxyopidae (1), Clubionidae (1), Cheiracanthiidae (1), Corinnidae (1) and Linyphiidae (1). Similar results with our study were also reported by Brown et al. (2003) who observed dominant families were Araneidae, Tetragnathidae, Lycosidae, Salticidae, Ganophosidae, Theridiidae in horticultural ecosystems. Deshmukh and Chaudhari (2016) reported maximum diversity of spider families were Araneidae, Salticidae and Lycosidae in citrus ecosystems.  and Bhat et al. (2013) also found the maximum diversity in families Araneidae followed by Tetraganthidae and Lycosidae in horticultural ecosystem. Tahir et al. (2015) found most dominant family in citrus ecosystem was Lycosidae followed by Salticidae, Araneidae and Linyphiidae while the present study revealed the dominant family was Araneidae followed by Lycosidae, Salticidae and Lynphillidae. In case of ground dwelling spider's maximum diversity was found in the families' Lycosidae followed by Ganophosidae and Salticidae which are also agreement with the results of Tahir et al. (2011). In winter season maximum diversity was found in the families' Clubionidae and Corrinnidae similar results also found by Divina and Jorge (1999) in lime orchard. Stenchly et al. (2011), Kacar (2015 and Asarkar and Ade (2017) also found same results in horticultural ecosystems. On the other hand the one third of the collection period belonged in monsoon season and the study area experiencing heavy rainfall because of heavy rainfall the effectiveness of pitfall traps were reduced.
At maize ecosystems a total of 615 Nos. individuals of Archinids were collected which composed of 5 numbers of families under 15 Nos. of genus and 29 Nos. of species. The maximum diversity of araneofauna was found in generic level in family Araneidae (7) followed by Tetragnathidae (4), Salticidae (2), Linyphiidae (1), Oxyopidae (1) and Lycosidae (1). On the other hand maximum individuals were found in family Araneidae (439) followed by Tetragnathidae (103), Salticidae (40), Linyphiidae (24), Lycosidae (9) and Oxyopidae (5). Similar results were reported from field crop ecosystems by Khan and Rather (2012), Joseph and Premila (2016) and Rajendran et al. (2017) who reported maximum diversity in families Araneidae followed by Tetraganthidae and Salticidae in field crop ecosystems. Rajeswaran et al. (2017) reported the families Oxyopidae and Lycosidae from maize ecosystem. Saranya et al. (2019) reported the dominated families Salticidae, Lycosidae and Oxyopidae and the genera Pardosa, Lycosa and Hippasa from maize ecosystem. The present study repoeted maximum diversity in orb weavers (Araneidae and Tetraganthidae) which may be attributed to the robust growth and development of maize crop i.e. the web spiders were observed to highly correlate with size and complexity of crop canopy and not prey availability, Greenstone (1984).
In potato ecosystem, a total of 103 Nos. individuals of Arachnids was collected with comprises of 5 Nos.
of families under 10 Nos. of genus and 12 Nos. of species. The maximum diversity at generic level was found in the family Ganophosidae (3) followed by Salticidae (3), Zodariidae (2), Cheiracanthiidae (1) and Lycosidae (1). Similar results were reported from Solanaceous crop ecosystems by  who reported the dominated ground dwelling spider family was Lycosidae in egg-plant ecosystem. Murali et al. (2017) reported the dominant families were Salticidae, Lycosidae, Oxyopidae, Araneidae and Cheiracanthiidae in brinjal ecosystem. Khan (2013) reported hunting and running spiders from temperate vegetable ecosystems from Kashmir. The present report maximum diversity found in ground dwelling spiders because of poor canopy development of potato crop due to prolonged dry spell and the abundance of areal spiders are positively correlated with complexity of canopy, Greenstone (1984).
At rice ecosystems a total of 567 Nos. individuals of Arachnids was collected comprising of with 10 Nos.

Alpha diversity
Deshmukh and Chaudhari (2016) reported Shannon diversity index and Evenness to be 1.98 and 0.9 respectively in Orange farm. Rajini (2016) reported the highest species diversity in banana ecosystem (3.55) followed by paddy field (3.23) and the lowest was observed in lady's finger ecosystem (2.30). In the case of Simpson index, the maximum value was 0.90 in banana ecosystem and the minimum was 0.55 in lady's finger field The species richness of spiders was greater in banana ecosystem (2.51) followed by paddy field (1.94). The evenness value was maximum in lady's finger ecosystem (0.87) followed by groundnut ecosystem (0.82). Zaki et al. (2015) found Shannon-Wiener Index and Simpson Index in between 0.76-1.48, 0.24-0.67 respectively in tomato ecosystem. Rendon et al. (2006) evaluated the biodiversity of 2 systems of coffee plantation and found ranges of Species richness (6-51), Shannon index (1.16-2.94), Simpson index (0.101-0.455). Bhat et al. (2013) found Shannon index (4.20), Simpson index (0.04), Evenness index (0.50), Margale D (14.73) in cashew system. Riaza et al. (2017) found the ranges of species richness (37-42), Eveness (0.71-0.88) and Shannon Wiener index (3.311-3.405) in sunflower and soybean field crop ecosystems. Stokmane and Spuņgis (2016) found the range of Shannon index to be 0.50 to 2.25 for ground-dwelling spiders and 0.14 to 1.86 for grass-dwelling spiders. Species evenness was 0.87 for the ground-dwelling spiders and 0.68 for the grass-dwelling spiders in calcareous fen ecosystem. Bhattacharya et al. (2017) found Shannon Wiener index (2.17) and Evenness index (0.7) in different ecosystem plotted in forest, shrub habitats and five numbers of houses from Meghalaya. Deshmukh and Raut (2014) found Shannon index 1.06, Simpson index 0.10, Margalef Richness Index 8.42 from different ecosystems. Bhuvad et al. (2011) recorded Simpson's index to be highest in mango (0.119) followed by rice (0.103), finger millet (0.081), cashew (0.054) and the values of Shannon diversity index was 3.41, 3.02, 2.81 and 2.73 in cashew, mango, finger millet and rice respectively. Goswami et al. (2015) found that Shannon diversity varied from 1.73-2.17, while Simpson index was between 0.13-0.18, Margelef richness index was found to be between 1.15-1.86, while Evenness index ranged between 0.69-0.72 at different growth stages of rice crop. Saranya et al. (2019)     Overall Arthropod diversity in terms of total individuals in observed ecosystems Values of Species number from 27th SMW of July, 2019 onwards till 06th SMW of February, 2020 in observed ecosystems