Spider Nutrition: An Integrative Perspective

The current research work aims to provide knowledge about the diversity of spiders’ fauna and their occurrence throughout the year from District Charsadda Khyber Pakhtunkhwa, Pakistan. Research data were collected from March-2015 to January-2017 from seven different localities of Charsadda District by using the camera, bottle, plastic bags, paraffin films, field book and 70% of ethylene alcohol and 20% of glycerine were used as chemicals. By using special identification keys, spiders were differentiated into families, genera and species. During the study time, a total of 2734 specimens of spiders were collected belonging from 35 genera, 15 families and 44 species were identified. Salticidae was the dominant family according to genera studied plus spiders samples numbers collected with 10 genera and 616 species specimens count. The high occurrence of spiders was studied during July. The result of the current study also shows a reduction of spider’s species in December due to lowering the temperature. The current study shows that Salticidae were the dominant family as capered to other species. The occurrence of spiders species greatly depends on changing the weather condition. The present study also shows great fluctuation in spider’s occurrence with changing of hot climate to colder during the study duration. Moreover, the wet season plays a great role in spiders’ population increase and growth.

Native grasslands are among the most imperiled of the North American ecosystems, but abandoned agricultural areas may provide suitable habitat for animal taxa that are endemic to grasslands. We studied how species diversity of orb-weaving spiders was influenced by secondary succession of a grassland plant community by monitoring the abundance and species diversity in study plots that were cultivated at 6-yr intervals and left uncultivated in the interim. We tested the hypothesis that local abundance and species diversity of spiders would be positively associated with time since cultivation because plant communities in older habitats would be more architecturally complex. Local abundance of spiders in general was not associated with time since cultivation, but abundance of Mangora gibberosa (Hentz) was positively associated with the abundance of perennial plants. Species richness and diversity of spiders also were positively associated with the abundance of perennial plants and reached a threshold a few years after cultivation. Species diversity of orb-weaving spiders seems to be strongly influenced by species composition of the plant community. Therefore, effective restoration of the structure and function of endemic communities of orb-weaving spiders may depend on preserving endemic grassland plant communities.

Trait diversity and spider community composition are associated with lower herbivory in young forest plantations

Spiders are successful natural enemies in different crops. Research on the role of spiders as natural enemies within agroecosystems needs to address the distribution of their communities across different spatial scales, as well as the dominant species. We studied the spatial distribution of the community of spiders of the olive agroecosystem in Northeastern Portugal and investigated potential species that could be used as bioindicators of agricultural management in the olive grove. We found nine functional groups (ambushers, foliage runner hunters, ground hunters, orb‐web builders, sheet web builders, sensing web‐builders, space web builders, stalkers and wandering sheet/tangle weavers) encompassing a community that changed significantly across the horizontal and vertical gradient. We propose Thanatus vulgaris Simon, 1870 as potential bioindicator for the ground of the olive grove central area and Ozyptila pauxilla (Simon, 1870) for the ground of the olive grove peripheral area. Adjacent shrubland areas could play an important role in biological control of pests, allowing the exchange of species and individuals with the olive crop. The role of agrobiont species as indicators of agricultural managements deserves further investigation towards the enhancement of the effectiveness of spiders within low‐impact crop management in arable landscapes.

Spiders often dominate predator assemblages in vineyard agroecosystems. Land‐use practices that enhance their diversity may be important for regional biodiversity conservation as well as biological control of vineyard pests. We surveyed ground‐dwelling spiders in habitats at different management intensities (natural habitat remnants, organic vineyards, and conventional vineyards) in the vineyard landscape of the Cape Floristic Region ( CFR ) biodiversity hotspot, South Africa, to examine the effects of local land use on spider diversity. Natural habitat remnants contributed significantly to the overall diversity, and supported rare families and unique species that were not found in the agricultural matrix. Nevertheless, vineyards still supported fairly high spider diversity, with a tendency for higher species richness in organic vineyards. Environmental variables relating to plant diversity, management intensity and distance to nearest natural habitat influenced spider abundance and species richness, and changes to these factors may improve the habitability of the vineyard landscape for spiders. All habitats supported various spider families that are known to prey on South African crop pests. In addition, spiders were abundant in both sampling seasons (autumn and spring), but showed a significant increase in vineyards early in the growing season, suggesting that they may provide early‐season background regulation of pests. There is considerable opportunity for spider conservation in the CFR vineyard landscape, as well as the possibility of associated benefits to biological control within vineyards.

Spider diversity plays an important role in the balance of nature. Thus, a study on the diversity of spiders was carried out in Awka, Anambra State in the South Eastern Nigeria from January, 2018 to June, 2018. Spiders were collected from three habitats which include: residential areas, farmlands and forest regions in the study area using handpicking and vegetative beating methods. A total of one hundred and twenty-five (125) spiders belonging to ten (10) families and comprising of thirteen (13) species were identified. Ninety-three (93) spiders were collected from residential areas, twenty-one (21) from farmlands and eleven (11) from forest regions. Results of the relative abundance of spider species in different habitat showed that Physocyclus globosus has the highest abundance of species having 71.2% with composition of eighty-nine (89) spiders. Residential areas recorded the highest abundance of spiders having 74.4% and species composition of ninety-three (93) spiders. Forest regions recorded the highest species diversity index (H) of 1.7202. The study revealed that spider diversity is influenced by the type of habitat, vegetation and environmental disturbances.Key words: Diversity; Habitat; Relative Abundance; Spider

Aim Factors acting at various scales may affect biodiversity, demanding analyses at multiple spatial scales in order to understand how community richness is determined. Here, we adopted a hierarchical approach to test the contribution of region, landscape heterogeneity, local management (organic vs. conventional) and location within field (edge vs. centre) to the species richness and abundance of spiders in cereals.Location Three regions of western and central Germany: Leine Bergland, Soester Boerde, and Lahn‐Dill Bergland.Methods Forty‐two paired organic and conventional winter wheat fields were compared. Field pairs were located in areas ranging from structurally simple to structurally complex landscapes. In May and June 2003, spiders were sampled using pitfall traps. Linear mixed models were used to determine the relationship of spider diversity and abundance with regional spatial factors and landscape heterogeneity within a 500‐m radius, as well as with local management and within‐field location.Results Within‐field location of the traps and landscape heterogeneity were the best predictors of species richness: more species were found in field edges and in heterogeneous landscapes. Region and local management had no effect on species richness. Activity density was higher in field edges and differed among regions.Main conclusions The diversity of farmland spiders was influenced by differences at two of the spatial scales (edge vs. centre, simple vs. complex landscapes), but not at the two others (field management, region), emphasizing the importance of analyses at a variety of spatial scales for an adequate explanation of patterns in biodiversity. Our study suggests that promoting heterogeneity in land use at landscape scales is one of the keys to promoting spider diversity in agroecosystems.

Adult aquatic insects emerging from streams may be a significant source of energy for terrestrial predators inhabiting riparian zones. In this study, we use natural abundance delta(13)C and delta(15)N values and an isotopic (15)N tracer addition to quantify the flow of carbon and nitrogen from aquatic to terrestrial food webs via emerging aquatic insects. We continuously dripped labeled (15)N-NH(4) for 6 weeks into Sycamore Creek, a Sonoran desert stream in the Tonto National Forest (central Arizona) and traced the flow of tracer (15)N from the stream into spiders living in the riparian zone. After correcting for natural abundance delta(15)N, we used isotopic mixing models to calculate the proportion of (15)N from emerging aquatic insects incorporated into spider biomass. Natural abundance delta(13)C values indicate that orb-web weaving spiders inhabiting riparian vegetation along the stream channel obtain almost 100% of their carbon from instream sources, whereas ground-dwelling hunting spiders obtain on average 68% of their carbon from instream sources. During the 6-week period of the (15)N tracer addition, orb-web weaving spiders obtained on average 39% of their nitrogen from emerging aquatic insects, whereas spider species hunting on the ground obtained on average 25% of their nitrogen from emerging aquatic insects. To determine if stream subsidies might be influencing the spatial distribution of terrestrial predators, we measured the biomass, abundance and diversity of spiders along a gradient from the active stream channel to a distance of 50 m into the upland using pitfall traps and timed sweep net samples. Spider abundance, biomass and richness were highest within the active stream channel but decreased more than three-fold 25 m from the wetted stream margin. Changes in structural complexity of vegetation, ground cover or terrestrial prey abundance could not account for patterns in spider distributions, however nutrient and energy subsidies from the stream could explain elevated spider numbers and richness within the active stream channel and riparian zone of Sycamore Creek.

Diversity of ground-active spiders in Negev desert habitats, Israel

Riparian spider abundance is influenced by the extent and architecture of litter, which is greatly influenced by flood regime. Flood-deposited clumps of intertwined plant material and inorganic debris (“litter hovels”) attached to trees and elevated above the ground by past high water events present a unique, persistent, and unstudied habitat type for spiders. We investigated spider use of litter hovels along an unregulated reach of West Clear Creek, Arizona, USA dominated by native riparian vegetation. Ninety two percent of litter hovels were occupied by at least one spider, with a mean occupancy of 4.5 spiders per hovel. Spider abundance and diversity at the family level were positively correlated with litter hovel size. Furthermore, spiders were non-randomly distributed among litter hovels in three areas of this riparian system: the vegetated floodplain, creek edges, and islands within the creek channel. Overall spider diversity was two-fold greater on creek islands than in the vegetated floodplain, and spider abundance also varied by predation guild among the three habitat types. Running and web-building spiders were most abundant on creek islands, while stalking and ambushing spiders were two-fold more abundant along creek edges in comparison with other habitats. For this riparian system, we estimate that spider densities could reach 270,000/ha in hovels alone, and therefore alteration of flood regimes through stream management may have important implications for arthropod dynamics. Current efforts to restore natural flood regimes and native vegetation in Southwestern streams are likely to benefit spider populations, their predators, and the regulation of herbivorous arthropods.

As anthropogenic climate induced stress leads to biodiversity loss and an increase in the frequency and severity of pest outbreaks, forest management in Central Europe is looking for ways to balance demands of biodiversity conservation and economic utility. To fulfil these demands Central European forestry is shifting from monoculture plantations to mixtures with phylogenetically distant deciduous and coniferous tree species which have been show to promote biodiversity and top-down control. Furthermore, the utilization of non-native Douglas fir, which combines climate change adaptability and high growth rates, is increasing and Norway spruce dieback is likely to exacerbate this. The ecological consequences of such an increase in non-native Douglas fir utilization are not fully known, but it is likely to lead to diversity and abundance loss of generalist arthropod predators, which in turn could translate to lower top-down control and higher herbivory (Chapter 1). In addition to testing this hypothesis, I will study if non-native Douglas fir effects are tempered in mixtures with phylogenetically distant European beech and to what extent Douglas fir effects are similar to effects of the phylogenetically close Norway spruce. Firstly I studied how Non-native Douglas fir affected the diversity, abundance and biomass of epigeal spiders collected by pitfall traps in mature forest stands (Chapter 2). Contrary to my expectations, epigeal spider abundance, biomass and functional richness was higher in stands with higher Douglas fir proportions, with site conditions playing a crucial role in structuring spider communities. Further analysis on arboreal spiders collected by tree beating in young forest stands (Chapter 3) showed that arboreal spiders have the highest numbers on individual conifer trees, especially Douglas fir. However, at the plot level spider species richness, abundance and biomass decreased with an increasing proportion of both Douglas fir and Norway spruce due to lower species turnover among coniferous trees (Matevski & Schuldt, 2021). These results suggest that it is important to consider matters of scale, stratum and forest age when discussing Douglas fir effects on spider diversity and top-down control potential. To see whether Douglas fir effects on spider top-down control potential translate into effects on predation pressure, we assessed clay caterpillar attack rates on the ground and herb layer in mature forest stands (Chapter 4). The results from this study (Matevski et al., 2021) showed that Douglas fir monocultures harbored significantly higher ground layer arthropod attack rates than all other stands, except for Norway spruce monocultures. Additional analysis on European beech sapling and mature tree leaf damage in monocultures as well as mixtures with Douglas fir and Norway spruce (Chapter 5) showed that stands with higher Douglas fir proportion suffered less sapling and mature European beech leaf damage. The results of these two manuscripts show that Douglas fir effects on spider diversity and community composition translate into effects on arthropod-mediated top-down control. All in all, my thesis suggests that, at least in the context of generalist arthropod predator diversity and ecosystem functioning, Douglas fir effects are mostly congruent with forest management demands by promoting diversity and economic utility (Chapter 6). Nonetheless, these results are dependent on stand age, site conditions, stratum and spatial scale studied, highlighting the importance of considering these factors when studying tree diversity and identity effects on arthropod diversity and ecosystem functioning.

Bamboo in Indonesia grows in clumps that create habitats that support biodiversity that can be studied through bioindicators, such as spiders that act as biological control agents as well as indicators of ecosystem diversity. This research was carried out with the aim of determining the diversity of spiders in bamboo clumps. The spider collection method is Hand Collecting and Beating. The results of the study found 14 species from 14 genera, 10 spider families consisting of 38 individuals. The species with the highest number of individuals is Ctenus hibernalis which reaches 14 individuals, while most other species only have a number of individuals between 1 to 3. This variation in the number of individuals per species is likely due to factors such as habitat differences, spider behavior, and the effectiveness of each collection method.

Spiders are generalist predators which have been found to benefit paddy crops as biological control agents. The present study was taken up at Bargarh district of Odisha, India to study and compare the spider diversity in the two cropping seasons with effect of abiotic factors on species abundance in rice lands. The observations were made across two cropping seasons during Rabi and Kharif cropping seasons to assess the seasonal influence on spider population. Seventeen families of spiders were recorded during the study out of which Rabi cropping season recorded 17 families, while Kharif season recorded 13 families. In total, 60 genera and 93 species were identified based on 2694 individuals collected where females recorded 67.6% while 18.8% were juveniles and 13.6% were male spiders. The highest species diversity was found in Araneidae family (28) while Tetragnathidae (n=1106) recorded the highest abundance. The correlation of spider abundance with abiotic factors was found to vary in both cropping seasons, where rainfall and windspeed were found to control spider colonization to a considerable extent but not found significantly corelated to abundance, while it was strongly correlated positively with relative humidity. Spider abundance and species diversity was more in the Rabi season (summer crop). Five dominant families were reported commonly from both cropping seasons: Tetragnathidae, Araneidae, Lycosidae, Salticidae and Oxyopidae. Spiders observed during the study belonged to seven different feeding guilds.

Geoff A. Parker

Sustainable agro-ecological design is challenging when the goal is self-regulation of the system. The objective of this study was to evaluate if the agropastoral design system affects the spider community, as spiders are the main predators in these production systems, and to determine those designs which maximize the diversity and density of spiders. The study was conducted during 2009/2010, at the Experimental Research Station of Agriculture (EEA-INTA) Reconquista (Santa Fe, Argentina) where we considered four different designs: C1 (five agricultural fields), C2 (three agricultural fields and four livestock fields), C3 (six agricultural fields and one livestock field) and C4 (five agricultural fields and one forest area). In each design, the spiders were collected by pitfall traps and suction samples with a G-Vac (garden-vacuum). The designs proposed were considered on the basis of environmental heterogeneity. The C4 treatment had the greatest number of species, followed by C2, C3 and C1 (183, 178, 144 and 142 species, respectively), and C2 presented the greatest abundance of spiders followed by C4, C3 and C1 (n=5708, 4785, 4271 and 3448, respectively). Eight guilds were present in C3 and C4. This study is the first to evaluate the diversity of spiders in agropastoral systems in Argentina. Our results show that designs that include more fields with livestock or equal to those for agriculture, as well as forest areas, increase environmental heterogeneity. Therefore, the presence of a biological controller and dominant predatory group will be possible with sustainable designs that have environmental heterogeneity, contributing to improved pest control in agricultural systems.