Assessment of arthropod diversity patterns in maize fields bordered by diverse cultivated refuge strips

In order to provide more evidence for the evaluation of the ecological risks of transgenic maize, arthropod population dynamics and biodiversity in fields planted with two kinds of transgenic maize (DBN9868, expressing the PAT and EPSPS genes, and DBN9936, expressing the Cry1Ab and EPSPS gene) were investigated by direct observation and trapping for three years. The recorded arthropod species belonged to 19 orders and 87 families, including Aphidoidea, Chrysomelidae, Coccinellidae, Chrysopidae and Araneae. The species richness, Shannon–Wiener diversity index, Pielou evenness index, dominance index and community similarity index of arthropod communities in maize fields were statistically analyzed, and the results showed that (1) the biodiversity difference of arthropod communities between transgenic maize and non-transgenic maize was smaller than that between different conventional cultivars; (2) the differences between ground-dwelling arthropod communities were less obvious than those between plant-inhabiting arthropod communities; and (3) Lepidoptera, the target pests of Bt maize, were not the dominant population in maize fields, and the dominant arthropod population in maize fields varied greatly between years and months. Combining those results, we concluded that the transgenic maize DBN9868 and DBN9936 had no significant effect on the arthropod communities in the field.

Intensive, large-scale cultivation has led to a postulated decrease in biodiversity worldwide, which has been ascribed to fragmentation and degradation of natural habitat bordering crop fields. Maize is the most widely planted grain crop in Grassland and Savanna Biomes of South Africa, but the effect that crop production has on surrounding species diversity and composition is unknown. This study intends to address this knowledge gap by comparing diversity patterns and species assemblages between maize fields and margins of six localities in South Africa across two biomes for plants and associated arthropods. A total of 15,019 individuals and 824 native and exotic plant species were recorded and 39 497 individuals and 1 629 morpho-species for arthropods. Although biodiversity loss was apparent in maize fields, plant and arthropod diversity remained the same for rangeland at shorter (30–100 m) and longer (100–400 m) distances from maize fields, suggesting that distance from maize fields had no effect on biodiversity patterns beyond 30 m. Plant species assemblages were best correlated with agricultural disturbance while arthropod communities were mainly correlated with biome. Our results suggest that the crop field margins (30–100 m from field edge) were not species poor ecosystems, but were surprisingly rich in plant and arthropod diversity. Field margins may therefore be of conservation value in the agricultural landscape with a diversity of species supporting important ecosystem services.

In 2015, the failure of the Fundão dam in Mariana, Brazil released ~43 million m3 of iron mining tailings into the environment. Despite restoration initiatives in the following years, few studies-and most focused on revegetation-have evaluated the effectiveness of the restoration process in areas impacted by the disaster. We aimed to evaluate the responses of the arthropod community in areas impacted by iron mining tailings deposition from the Fundão dam that is in the restoration process. We defined sampling units in the riparian zone of the Gualaxo do Norte River, which is under restoration, and in a native not impacted riparian zone. We collected soil arthropods using pitfall traps and sampled environmental variables in the same sites. We used generalize least squares models (GLS) to test if the restored areas already presented values of arthropod diversity and functional group abundance similar to the reference area and to test which environmental variables are influencing arthropod diversity. We also tested how large the differences of arthropod community composition between the study areas and used the index of indicator species (IndVal) to verify which species could be used as an indicator of reference or restoration areas. The diversity of arthropods and the functional groups of detritivores and omnivores were higher in the native riparian zone. Understory density, soil density, organic matter content, and microbial biomass carbon were the environmental variables that significantly explained the diversity and species composition of arthropods. We show that restoration areas still have different soil arthropod diversity values and community composition when compared to reference areas. Evaluating the response of the arthropod community to the restoration process and long-term monitoring are essential to achieve a satisfactory result in this process and achieve a self-sustaining ecosystem.

The effects of phytase transgenic maize on the community components and diversity of arthropods

Ecological restoration enjoys widespread use as a technique to mitigate for environmental damage. Success of a restoration project often is evaluated on the basis of plant cover only. Recovery of a native arthropod fauna is also important to achieve conservation goals. I sampled arthropod communities by pitfall trapping in undisturbed, disturbed, and restored coastal sage scrub habitats in southern California. I evaluated arthropod community composition, diversity, and abundance using summary statistics, cluster analysis, and detrended correspondence analysis (DCA) and investigated influence of vegetation on arthropod communities with multiple regression analysis. Arthropod diversity at undisturbed and disturbed sites was greater than at sites that were 5 and 15 years following restoration ( p < 0.05). Number of arthropod species was not significantly different among undisturbed, disturbed, and restored sites, and two restoration sites had significantly more individuals than other sites. Vegetation at disturbed and undisturbed sites differed significantly; older restorations did not differ significantly from undisturbed sites in diversity, percent cover, or structural complexity. In multiple regression models, arthropod species richness and diversity was negatively related to vegetation height but positively related to structural complexity at intermediate heights. Exotic arthropod species were negatively associated with overall arthropod diversity, with abundance of the earwig Forficula auricularia best predicting diversity at comparison (not restored) sites (r2 = 0.29), and abundance of the spider Dysdera crocata and the ant Linepithema humile predicting diversity at all sites combined (r2 = 0.48). Native scavengers were less abundant at restored sites than all other sites and, with a notable exception, native predators were less abundant as well. DCA of all species separated restored sites from all other sites on the first axis, which was highly correlated with arthropod diversity and exotic arthropod species abundance. Lower taxonomic levels showed similar but weaker patterns, with example families not discriminating between site histories. Vegetation characteristics did not differ significantly between the newly restored site and disturbed sites, or between mature restoration sites and undisturbed sites. In contrast, arthropod communities at all restored sites were, as a group, significantly different from both disturbed and undisturbed sites. As found in other studies of other restoration sites, arthropod communities are less diverse and have altered guild structure. If restoration is to be successful as compensatory mitigation, restoration success standards must be expanded to include arthropods.

Intensive agriculture has caused significant declines in ground-dwelling arthropod diversity and ecosystem services. Chemical and organic fertilizers alter arthropod habitats, affecting arthropod community abundance and diversity. Fertilization treatments differentially affect arthropod communities, and various soil physico-chemical properties differentially affect various species in the arthropod community. Studying arthropod diversity, community structure, and soil physico-chemical properties under various fertilization treatments is crucial to understanding the impact of agricultural activities. We used pitfall traps to catch ground-dwelling arthropods four times a year, and analyzed arthropod abundance and biodiversity indices under different fertilization treatments The study revealed that Lycosidae and Araneidae were the dominant family in the study area. Notably, the application of both chemical and organic fertilizers led to a decrease in ground-dwelling arthropod diversity compared to unfertilized treatments. Furthermore, our analysis indicated that the strongest environmental predictors of ground-dwelling arthropod community variation varied depending on the fertilization method, and different species were affected differently by soil physico-chemical properties. Specifically, when no fertilization was applied, soil total potassium and available phosphorus were the strongest predictors of arthropod diversity. Conversely, organic matter became the primary determinant when organic fertilizers were used alone. Interestingly, when chemical and organic fertilizers were combined, soil total nitrogen, pH, and available phosphorus were identified as the principal drivers. Additionally, our findings highlighted that the dominant group of ground-dwelling arthropods was particularly sensitive to changes in biomass, available nitrogen, and available potassium.

有机肥和植被去除管理对人工林土壤节肢动物多样性的影响

Arthropods are critical ecosystem components due to their high diversity and sensitivity to perturbation. Furthermore, due to their ease of capture they are often the focus of environmental health surveys. There is much debate regarding the best sampling method to use in these surveys. Sweep netting and pan trapping are two sampling methods commonly used in agricultural arthropod surveys, but have not been contrasted in natural grassland systems at the community level. The purpose of this study was to determine whether sweep netting was effective at estimating arthropod diversity at the community level in grasslands or if supplemental pan trapping was needed. Arthropods were collected from grassland sites in Montana, USA, in the summer of 2011. The following three standardized evaluation criteria (consistency, reliability, and precision) were developed to assess the efficacy of sweep netting and pan trapping, based on analyses of variations in arthropod abundances, species richness, evenness, capture frequency, and community composition. Neither sampling method was sufficient in any criteria to be used alone for community-level arthropod surveys. On a taxa-specific basis, however, sweep netting was consistent, reliable, and precise for Thysanoptera, infrequently collected (i.e., rare) insects, and Arachnida, whereas pan trapping was consistent, reliable, and precise for Collembola and bees, which is especially significant given current threats to the latter's populations worldwide. Species-level identifications increase the detected dissimilarity between sweep netting and pan trapping. We recommend that community-level arthropod surveys use both sampling methods concurrently, at least in grasslands, but likely in most nonagricultural systems. Target surveys, such as monitoring bee communities in fragmented grassland habitat or where detailed information on behavior of the target arthropod groups is available can in some instances employ singular methods. As a general ecological principle, consistency, reliability, and precision are appropriate criteria to evaluate the applicability of a given sampling method for both community-level and taxa-specific arthropod surveys in any ecosystem.

The lush leaves of tea within several years after prune is expected to be followed by arthropod abundance and diversity. The study aimed to evaluate the arthropod abundance, diversity, evenness, and dominance, at the tea plantation within several years after the prune. The study was conducted at Pagilaran tea plantations, Central Java, from April to May 2018, at an altitude of 900 m asl. Arthropod samplings were done in four plots of tea plantation namely 1, 2, 3, and 4 years after pruning, hereafter they are called PY1, PY2, PY3, and PY4. The plot area was approximately 1 ha. The arthropod specimens were collected using sweep net and pitfall trap every day for 6 consecutive days. The arthropod identification and calculation were carried out in the Laboratory of Entomology, Faculty of Agriculture, Universitas Gadjah Mada. Analysis of variance was applied to determine the effect of PY on the Arthropod abundance. The Shannon Wienner index, the Evenness index, and the Simpson index, were used to evaluate the arthropod diversity, evenness, and dominance, respectively. The results showed that the PY significantly affected the arthropod abundance. The arthropod number collected from PY1 (27 individuals/50 swings) was significantly lower as compared to the other PYs, while arthropod numbers amongst PY2, PY3, and PY4 (53, 93, and 67 individuals/50 swings, respectively) were relatively similar. Out of the total number of 1.432 arthropod specimens, it comprised of 10 orders at which Hemiptera was the highest order (48.04%), and 69 families at which Cicadellidae was the highest family (32.12%). Amongst specimens of Cicadellidae, there was Empoasca sp. which is an important tea pest. The Shannon Wienner index (H) of orders and families ranged from 1.24 to 2.69 indicates moderate arthropod diversity. The Evenness index (e') ranged from 0.57 to 0.91) indicates the arthropod evenly distributed. Meanwhile, the Simpson index (D) ranged 0.10 - 0.39 indicates that there was no dominance of the order or family.

In the Eastern Cape, natural landscapes that are adjacent to rivers and the sea are threatened by illegal sand mining, which occurs without prior assessment of biodiversity. Sand mining activities lead to the reduction of vegetation cover and plant species richness. Generally, species richness of arthropods correlates positively with plant species richness. Thus, it is important to test the effect of sand mining on arthropod diversity. In this study we compared species richness, abundance, Shannon-Wiener diversity and composition of ants, beetles and spiders between sand-mined areas and the surrounding grassland. Arthropods were collected using pitfall traps in eight plots in the sand-mined area and eight plots in the surrounding grassland. The sand-mined area and the grassland supported similar species richness and abundance of arthropods. However, significantly greater diversity was in the surrounding grassland than the sand-mined area. Furthermore, species composition of arthropods between the two areas was significantly different. Additionally, there were 13 morphospecies that were indicators of the sand-mined area, and ten morphospecies that were indicators of the surrounding grassland, while there were no shared indicator species between the two study areas. As such, disturbance-tolerant species that prefer open habitats may have replaced specialist arthropods. Given that our study showed that illegal sand mining changes species composition and reduce the diversity of arthropods, sand mining should be restricted to designated areas to reduce the impact of mining on arthropods and improve conservation.

Ecological engineering of ground cover vegetation enhances the diversity and stability of peach orchard canopy arthropod communities

Green roofs, which are roofs with growing substrate and vegetation, can provide habitat for arthropods in cities. Maintaining a diversity of arthropods in an urban environment can enhance the functions they fill, such as pest control and soil development. Theory suggests that the creation of a heterogeneous environment on green roofs would enhance arthropod diversity. Several studies have examined how arthropod diversity can be enhanced on green roofs, and particularly whether substrate properties affect the arthropod community, but a gap remains in identifying the effect of substrate heterogeneity within a green roof on the arthropod community. In this paper, it is hypothesized that creating heterogeneity in the substrate would directly affect the diversity and abundance of some arthropod taxa, and indirectly increase arthropod diversity through increased plant diversity. These hypotheses were tested using green roof plots in four treatments of substrate heterogeneity: (1) homogeneous dispersion; (2) mineral heterogeneity—with increased tuff concentration in subplots; (3) organic heterogeneity—with decreased compost concentrations in subplots; (4) both mineral and organic heterogeneity. Each of the four treatments was replicated twice on each of three roofs (six replicates per treatment) in a Mediterranean region. There was no effect of substrate heterogeneity on arthropod diversity, abundance, or community composition, but there were differences in arthropod communities among roofs. This suggests that the location of a green roof, which can differ in local climatic conditions, can have a strong effect on the composition of the arthropod community. Thus, arthropod diversity may be promoted by building green roofs in a variety of locations throughout a city, even if the roof construction is similar on all roofs.

Most crop plants are grown far from their region of origin and have been significantly altered by human selection. Given the importance of biodiversity in ecosystem function, surprisingly little is known about the effect of domestication on arthropod diversity and community composition. Arthropod diversity and species abundance were compared with three genotypes of cultivated rice Oryza sativa L. and two genotypes of wild rice O. rufipogon Griff. in southern Luzon, the Philippines. Domestication had a small but positive effect on total arthropod diversity. Arthropod species richness was highest on the cultivar IR64 and lowest on one of the O. rufipogon genotypes, although arthropod community composition was similar across rice genotypes. Total arthropod abundance and the relative abundance of guilds did not differ between wild and cultivated rice. All common herbivores, however, responded to rice domestication. Stem‐boring moths and several sap‐sucking herbivores benefited from domestication, although domestication reduced densities of the wolf spider Pardosa pseudoannulata Boesenberg et Strand. By contrast to previous assumptions, crop domestication may not always decrease arthropod diversity. We did not detect any changes in biodiversity or community composition suggesting that rice domestication has altered the capacity of the arthropod community to regulate herbivores.

The biodiversity of an agroecosystem is not only important for its intrinsic value but also because it influences ecological functions that are vital for crop production in sustainable agricultural systems and the surrounding environment. A concern about genetically modified (GM) crops is the potential negative impact that such crops could have on diversity and abundance of nontarget organisms, and subsequently on ecosystem functions. Therefore, it is essential to assess the potential environmental risk of the release of a GM crop and to study its effect on species assemblages within that ecosystem. Assessment of the impact of Bt maize on the environment is hampered by the lack of basic checklists of species present in maize agroecosystems. The aims of the study were to compile a checklist of arthropods that occur on maize in South Africa and to compare the diversity and abundance of arthropods and functional groups on Bt maize and non-Bt maize. Collections of arthropods were carried out during two growing seasons on Bt maize and non-Bt maize plants at two localities. Three maize fields were sampled per locality during each season. Twenty plants, each of Bt maize and non-Bt maize, were randomly selected from the fields at each site. The arthropods collected during this study were classified to morphospecies level and grouped into the following functional groups: detritivores, herbivores, predators, and parasitoids. Based on feeding strategy, herbivores and predators were further divided into sucking herbivores or predators (piercing-sucking mouthparts) and chewing herbivores or predators (chewing mouthparts). A total of 8,771 arthropod individuals, comprising 288 morphospecies and presenting 20 orders, were collected. Results from this short-term study indicated that abundance and diversity of arthropods in maize and the different functional guilds were not significantly affected by Bt maize, either in terms of diversity or abundance.

Abstract. Pasaribu DN, Rizali A, Tarno H, Priawandiputra W, Johannis M, Buchori D. 2024. Agricultural landscape composition alters ant communities in maize fields more than plant diversity enrichment. Biodiversitas 25: 205-213. Fragmented natural habitats in human-modified landscapes play a crucial role in conserving biodiversity. Ants, as keystone species, are integral to terrestrial ecosystems, making it essential to comprehend the factors influencing their survival. This study investigates the impact of agricultural landscape composition and plant diversity enrichment (flowering plants) management on shaping ant communities in maize (Zea mays L.) fields. The research occurred in maize fields surrounded by other crops, semi-natural habitats, and housing areas in Malang District, East Java, Indonesia. The four agricultural areas were divided into control and treatment plots, considering landscape composition parameters, particularly Class Area (CA) and the Number of Patches (NP), measured within a 500 m radius. The landscape around the maize fields was characterized by manually digitizing land use. Six types of plant diversity enrichment were employed in this study: wild cosmos (Cosmos caudatus), white buttercup (Turnera subulata), sunflower (Helianthus annuus), long bean (Vigna unguiculata), ornamental bean (Arachis pintoi), and coral vine (Antigonon leptopus). The study was divided into the dry season (April-July 2022) and the wet season (September-December 2022). Ant sampling was conducted using pitfall traps and, based on generalized linear models, revealed that plant diversity enrichment management did not affect species richness, abundance, or composition of ants. Landscape composition positively influenced ant species richness but negatively impacted species composition, particularly the number of semi-natural habitat patches. Maize crop age also positively influenced ant species richness but negatively affected beta diversity. Wet season was also found to have a negative effect on beta diversity. In conclusion, the proportion of semi-natural habitats in agricultural landscapes and crop age contribute significantly to species richness and species composition of ants.