Soil microarthropods affect soil ecosystems in a manner that may contribute to balancing the goals of building soil health and controlling weeds in organic agricultural systems. While soil microarthropod feeding behavior can affect plant growth, their impacts on plant communities in agricultural systems are largely unknown. A greenhouse experiment was conducted to investigate the impacts of microarthropods on weed communities. A model weed seed bank was used in each mesocosm, which included yellow foxtail (Setaria pumila (Poir.) Roem&Schult.), giant foxtail (Setaria faberi Herrm.), Powell amaranth (Amaranthus powellii S. Watson), water-hemp (Amaranthus tuberculatus (Moq.) Sauer), common lambsquarters (Chenopodium album L.), and velvetleaf (Abutilon theophrasti Medik.). The study included three treatments: Collembola (Isotomiella minor, Schaffer 1896) abundance (none, low, high), soil microbial community (sterilized/non-sterilized), and fertilizer (presence/ absence of compost). A lab experiment examining individual weed species interactions with I. minor was conducted to elucidate the mechanisms driving the greenhouse experiment findings. Twenty seeds of each weed species were placed on moistened germination paper in containers with varying I. minor abundance levels (none, low, high, very high). Seed germination was recorded after five and seven days. In the greenhouse, the presence of I. minor increased total weed emergence during the first two weeks, but this effect diminished after three weeks. Increasing I. minor abundances generally decreased weed biomass, though this effect was greater in the non-sterilized soil. In the non-sterilized soil, I. minor presence decreased total aboveground weed biomass production by up to 23 %. The Amaranthus species, Powell amaranth and waterhemp, drove this effect with a 55 % and 32 % reduction in biomass, respectively. In tandem, the Amaranthus species had reduced abundances in the presence of I. minor. I. minor increased yellow foxtail germination in the lab, while not affecting the other weed species. This suggests that their effects on the Amaranthus weeds in the greenhouse were likely not caused by direct effects on germination, but instead through nutrient cycling or root herbivory. The proposed mechanism underlying these interactions is that I. minor can initially stimulate germination by feeding on seed coats, but when the seed coats are minimal can damage the seedling. Our findings indicate I. minor could impact weed growth in a manner that affects management decisions and outcomes.

BackgroundForensic entomotoxicology is a crucial field that studies the effects of drugs and poisons on carrion-feeding insects, particularly in crime investigations. Hydrogen cyanamide, a plant growth regulator, is hazardous and used in agriculture but is limited in some countries due to its high cost and severe toxicity. The terrestrial isopod Porcellio laevis plays a vital role in soil ecosystems and biosystem management. Accordingly, authors aimed to examine the impact of hydrogen cyanamide toxicity on arthropods, specifically Porcellio laevis, Musca domestica (House flies), and Sarcophaga sp. (Flesh flies) visiting decomposing covered/uncovered rat carrions, which could be relevant in forensic investigations. A total of 20 rats were divided into two control (I and II, covered/uncovered) and two treated groups (III and IV, covered/uncovered, euthanized using hydrogen cyanamide). Arthropods were gathered bi-daily during the initial week and then once daily for a duration of 1 month and were assessed for growth rate. Morphological and histological alterations were analyzed using light and electron microscopes.ResultsThe results revealed that hydrogen cyanamide caused a delay in postmortem interval (PMI) by 22-33 h in certain insect species, particularly in uncovered carrion. Severe damage was observed in the carrions of Groups III and IV, specifically Porcellio laevis.ConclusionA scanning electron microscope (SEM) would be beneficial for scrutinizing insects as postmortem toxicological specimens.

Seasonal changes in vegetation and climate exert significant influences on soil fauna in natural and agricultural ecosystems. Additionally, evidence indicates that interactions between different plant layers promote soil fauna diversity through the variety of resources available. The objective was to assess the edaphic fauna in traditional land use systems, agroforestry systems and natural vegetation, under the influence of rainfall seasonality and plant strata in the semiarid region of Brazil. For this purpose, six types of land use were selected: agroforestry; silvopastoral; slash and burn with intensive use without fallow; slash and burn with six years of fallow; slash and burn with nine years of fallow; and a system representing the natural vegetation of the Caatinga. Edaphic fauna was collected using pitfall traps in the dry and rainy seasons. A total of 43,363 individuals of the edaphic fauna were collected and grouped into taxa, determining abundance, diversity and functional groups. The results revealed higher abundance and diversity of edaphic fauna in the rainy season across all land use systems, but significantly higher numbers in systems with tree strata. The greater the abundance, richness and diversity of trees, the higher the diversity of edaphic fauna (Shannon Index - H: 0.7 < H- < 1) for the seasonal effect. Agroforestry systems were intermediate in the diversity of edaphic fauna (H- < 0.8) compared to other systems. Systems with greater heterogeneity in tree and herbaceous strata were the ones that most increased the diversity and activity of functional groups of edaphic fauna (H < 0.8; 0.5 < r < 0.9). In semiarid conditions, more attention should be given to agricultural production systems with greater tree diversity and interaction between tree and herbaceous strata to conserve the biodiversity of edaphic fauna and improve the soil health.

The more insects there are, the more food there is for insectivores and the higher the likelihood for insect-associated ecosystem services. Yet, we lack insights into the drivers of insect biomass over space and seasons, for both tropical and temperate zones. We used 245 Malaise traps, managed by 191 volunteers and park guards, to characterize year-round flying insect biomass in a temperate (Sweden) and a tropical (Madagascar) country. Surprisingly, we found that local insect biomass was similar across zones. In Sweden, local insect biomass increased with accumulated heat and varied across habitats, while biomass in Madagascar was unrelated to the environmental predictors measured. Drivers behind seasonality partly converged: In both countries, the seasonality of insect biomass differed between warmer and colder sites, and wetter and drier sites. In Sweden, short-term deviations from expected season-specific biomass were explained by week-to-week fluctuations in accumulated heat, rainfall and soil moisture, whereas in Madagascar, weeks with higher soil moisture had higher insect biomass. Overall, our study identifies key drivers of the seasonal distribution of flying insect biomass in a temperate and a tropical climate. This knowledge is key to understanding the spatial and seasonal availability of insects-as well as predicting future scenarios of insect biomass change.

All ecosystems face ecological challenges in this century. Therefore, it is becoming increasingly important to understand the ecology and degree of local adaptation of functionally important Arctic-alpine biomes by looking at the most diverse taxon of metazoans: the Arthropoda. This is the first study to utilize metabarcoding in the Alpine tundra, providing insights into the effects of micro-environmental parameters on alpha- and beta-diversity of arthropods in such unique environments. To characterize arthropod diversity, pitfall traps were set at three middle-alpine sampling sites in the Scandinavian mountain range in Norway during the snow-free season in 2015. A metabarcoding approach was then used to determine the small-scale biodiversity patterns of arthropods in the Alpine tundra. All DNA was extracted directly from the preservative EtOH from 27 pitfall traps. In order to identify the controlling environmental conditions, all sampling locations were equipped with automatic data loggers for permanent measurement of the microenvironmental conditions. The variables measured were: air temperature [degrees C] at 15 cm height, soil temperature [degrees C] at 15 cm depth, and soil moisture [vol.%] at 15 cm depth. A total of 233 Arthropoda OTUs were identified. The number of unique OTUs found per sampling location (ridge, south-facing slope, and depression) was generally higher than the OTUs shared between the sampling locations, demonstrating that niche features greatly impact arthropod community structure. Our findings emphasize the fine-scale heterogeneity of arctic-alpine ecosystems and provide evidence for trait-based and niche-driven adaptation. The spatial and temporal differences in arthropod diversity were best explained by soil moisture and soil temperature at the respective locations. Furthermore, our results show that arthropod diversity is underestimated in alpine-tundra ecosystems using classical approaches and highlight the importance of integrating long-term functional environmental data and modern taxonomic techniques into biodiversity research to expand our ecological understanding of fine- and meso-scale biogeographical patterns. Our study examines the alpha- and beta-diversity of arthropods in the Arctic-alpine biomes of the Scandes using environmental DNA (eDNA)/metabarcoding. We found that micro-climatological parameters such as air/soil temperature and soil moisture significantly influence the arthropod community structure, highlighting the fine-scale heterogeneity of these ecosystems. Our study emphasizes the importance of integrating long-term functional environmental data and modern taxonomic techniques to accurately assess arthropod diversity and broaden our understanding of biogeographical patterns in alpine-tundra ecosystems.image

Snow is one of the most important factors in the ecology of alpine ecosystems. In Australia, both the depth and duration of snow cover have declined significantly in recent decades and this trend is projected to continue with global warming. Many small arthropods remain active throughout the winter, within a space beneath the snowpack (subnivean) where the snow's insulation creates a thermally stable environment. Using field surveys and experimental manipulation of snow depth at two locations in the Australian alpine region, we explored the diversity of winter-active arthropods and their response to reduced snow. Individuals from 18 arthropod Orders were detected beneath the snow during winter, with Collembola, Araneae, Acari and Coleoptera accounting for 95-98% of the individuals collected. The subnivean taxa represented a distinct subset of those active outside the winter months. Removal of the snow layer increased daily temperature fluctuations, increased the number of days below freezing and raised the mean surface temperatures. Community composition was altered by snow removal, driven by changes in the numbers of two abundant springtail taxa at each location. We found a strong reduction in the abundances of both taxa at one study site, and contrasting responses (one strong positive and one strong negative) to snow removal at the second study site. Subnivean arthropod communities in Australia thus appear sensitive to snow conditions at small spatial scales.