Arthropods In Agroecosystems Research Articles

Monocrotaline presence in the Crotalaria (Fabaceae) plant genus and its influence on arthropods in agroecosystems.

Crotalaria (Fabaceae) occurs abundantly in tropical and subtropical regions and has about 600 known species. These plants are widely used in agriculture, mainly as cover plants and green manures, in addition to their use in the management of phytonematodes. A striking feature of these species is the production of pyrrolizidine alkaloids (PAs), secondary allelochemicals involved in plant defense against herbivores. In Crotalaria species, monocrotaline is the predominant PA, which has many biological activities reported, including cytotoxicity, tumorigenicity, hepatotoxicity and neurotoxicity, with a wide range of ecological interactions. Thus, studies have sought to elucidate the effects of this compound to promote an increase in flora and fauna (mainly insects and nematodes) associated with agroecosystems, favoring the natural biological control. This review summarizes information about the monocrotaline, showing such effects in these environments, both above and below ground, and their potential use in pest management programs.

Insight into Trophic Interactions of Spiders in Olive Groves with Integrated and Ecological Pest Management Using DNA Metabarcoding

Spiders act as one of the major predators among arthropods in agroecosystems and are crucial to the control of pest densities. As they are almost exclusively predators, they have developed a number of hunting strategies, which have consequently impacted their complex trophic interactions. The development of molecular biology methods for environmental DNA analysis has made it easier to analyze such complex trophic networks. In order to ascertain the trophic interactions of spiders, a sampling of spider species was carried out in two olive groves in Zadar County, Croatia, under integrated and ecological pest management. To construct the trophic networks of spiders, we performed DNA metabarcoding. The combined general and spider-excluding primers were able to recognize prey from 12 distinct orders in the guts of the 57 spiders. According to our results, spiders have a complex trophic network that exhibits seasonal and site-specific variations. The results obtained from both sites having different pest management also confirmed that spiders consumed phytophagous insects in the highest ratio, including some important pests, in comparison to other prey and that management and guild type had an impact on the predation of phytophagous insects.

秸秆还田对中国农田土壤节肢动物数量及多样性影响的整合分析

PDF HTML阅读 XML下载 导出引用 引用提醒 秸秆还田对中国农田土壤节肢动物数量及多样性影响的整合分析 DOI: 10.5846/stxb202111053105 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 江苏省自然科学基金项目（BK20200552）；国家自然科学基金项目（32001181）；江苏省博士后基金项目（2020Z201）；南京农业大学中央高校基本业务费项目（KJQN202113） Impacts of straw returning on the number and diversity of soil arthropods in China: A meta-analysis Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:秸秆还田是提高土壤生物数量和多样性的有效手段，但土壤节肢动物对秸秆还田的响应尚未明确。搜集2005到2020年国内有关秸秆还田对农田土壤节肢动物数量及多样性影响的25篇田间试验文献，分别获得230对土壤节肢动物数量数据和112对土壤节肢动物多样性数据，并采用整合分析方法探究不同气候类型、土层深度、种植制度、秸秆还田量、还田方式及还田时间下秸秆还田对农田土壤节肢动物数量及多样性的影响。结果表明，与不还田相比，秸秆还田总体上显著增加了农田土壤节肢动物的数量，但在亚热带季风气候区或还田时间大于5 a时，秸秆还田对节肢动物数量的增加效应则不显著；此外，秸秆还田对土壤节肢动物数量的促进作用还受到节肢动物体型的影响，秸秆还田显著增加土壤中小型节肢动物的数量，特别是蜱螨目类土壤节肢动物，但是对大型土壤节肢动物的促进作用并不显著。秸秆还田总体上也提高了农田土壤节肢动物的多样性，特别是在温带季风气候、年均温小于5℃、年均降水量小于600 mm、秸秆还田量大于10000 kg/hm2、轮作以及还田时间大于5 a这些条件下，秸秆还田能显著提高土壤节肢动物的多样性。回归分析结果显示随着秸秆还田时间的增加，土壤节肢动物数量的增加率显著降低，而随着秸秆还田量的增加，节肢动物数量的增加率则显著升高；节肢动物多样性的增加率随着年均降水量的增加显著降低，而随着秸秆还田时间和还田量的增加显著升高。以上结果表明，秸秆还田有助于提高农田土壤节肢动物的数量和多样性，但此效应会受到气候因子及农田管理方式的影响。 Abstract:Straw returning is an effective way to enhance the number and diversity of soil organisms, but the responses of soil arthropods to straw returning are still unclear. In this study, we conducted a meta-analysis involving 230 comparisons of soil arthropod number and 112 comparisons of soil arthropod diversity collected from 25 related literatures during 2005-2020. The objectives of this study are to assess the effects of straw returning on the number and diversity of soil arthropods in agroecosystems of China, as well as the variation of these effects under different climates, soil depths, cropping systems, straw returning amounts, straw returning methods and time. The results showed that straw returning significantly increased the number of soil arthropods compared with no straw returning, except the studies conducted at subtropical monsoon climate regions, or the time of straw returning was more than 5 a. In addition, the promotional effect of straw returning on soil arthropod number was also affected by the size of arthropods, with straw returning significantly increasing the number of small and medium-sized soil arthropods, especially acari, rather than large soil arthropods. Straw returning also had a tendency to increase the diversity of soil arthropods, and this effect was significant under the conditions of temperate monsoon climates, mean annual temperature less than 5℃, mean annual precipitation less than 600 mm, rotation cropping, amount of straw returning more than 10000 kg/hm2 and straw returning time more than 5 a. The regression analysis showed that the increased rate of soil arthropod number under straw returning significantly decreased with straw returning time, but it significantly increased with straw returning amount; the increased rate of soil arthropod diversity under straw returning decreased significantly with mean annual precipitation, but it significantly increased with straw returning amount and time. Together, these results indicated that straw returning could improve the number and diversity of soil arthropods, which could be affected by climate factors and agricultural managements. 参考文献 相似文献 引证文献

Suitability of spider mites and green peach aphids as prey for Eriopis connexa (Germar) (Coleoptera: Coccinellidae)

The ladybird Eriopis connexa is an important natural enemy of several pest arthropods in agroecosystems. High population of this predator is frequently observed in strawberry and soybean crops associated with spider mites. We used two-sex life table parameters to evaluate under laboratory conditions, the suitability of three species of spider mites (Tetranychus evansi, Tetranychus urticae, Tetranychus ogmophallos), and a species of aphid (Myzus persicae) as a prey for the predator E. connexa. Eriopis connexa completed immature development on all prey species except on T. evansi, in which all individuals of predator died before reaching the pupal stage. Among prey species that allowed the immature development of E. connexa, T. urticae and M. persicae provided a faster development time to the predator. Oviposition days, longevity and fecundity of E. connexa on T. urticae and M. persicae were substantially longer/higher than on T. ogmophallos. Net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of E. connexa feeding on T. urticae and M. persicae were also higher than those on T. ogmophallos. Based on the overall performance of the ladybird, the order of suitability of prey species was M. persicae > T. urticae > T. ogmophallos > T. evansi.

Supporting non-target arthropods in agroecosystems: Modelling effects of insecticides and landscape structure on carabids in agricultural landscapes

Intensification of agricultural practices is one of the most important drivers of the dramatic decline of arthropod species. We do not know, however, the relative contribution to decline of different anthropogenic stressors that are part of this process. We used high-resolution dynamic landscape models and advanced spatially-explicit population modelling to estimate the relative importance of insecticide use and landscape structure for population dynamics of a widespread carabid beetle Bembidion lampros. The effects of in-crop mitigation measures through the application of insecticides with reduced lethality, and off-crop mitigation measures by increasing abundance of grassy field margins, were evaluated for the beetle along the gradient of landscape heterogeneity. Reducing the insecticide-driven lethality (from 90 to 10%) had larger positive impacts on beetle density and occupancy than increasing the abundance of field margins in a landscape. The effects of increasing field margins depended on their width and overall abundance in the landscape, but only field margins 4 m wide, applied to at least 40% of fields, resulted in an increase in beetle population density comparable to the scenario with the smallest reduction of insecticide-driven lethality we considered. Our findings suggest the importance of field margins rather as a supporting not stand-alone mitigation measure, as they generally improved effects of reduction of insecticide-driven lethality. Therefore, adding sufficiently broad off-field habitats should help to maintain viable beetle populations in agricultural landscapes even with moderate use of insecticides. In general, the less persistent the insecticides are in the environment, the larger positive impacts of applied mitigation measures on beetle populations were found. We also showed that the effectiveness of applied mitigation measures strongly depends on landscape and farmland heterogeneity. Thus, to achieve the same management or mitigation target in different landscapes might require different strategies.

The Effect of Cover Crops on the Biodiversity and Abundance of Ground-Dwelling Arthropods in a Mediterranean Pear Orchard

The intensification of agriculture has led to the reduction of the diversity of arthropods in agroecosystems, including that of ground-dwelling species. The aim of our work was to assess the effect of a sown cover crop on the diversity of ground-dwelling arthropods, including key predators for pest control in pear orchards. The trial was carried out in a pear orchard divided in three blocks; two treatments (cover-cropping and control) were implemented in each block. A seed mixture of 10 plant species was used in the plots with the sown cover. The densities of ground-dwelling arthropods were sampled using pitfall traps. The ground cover had a significant impact on the diversity and abundance of arthropods. The Shannon–Wiener diversity index was significantly higher for the cover than for the control plots. Several families of spiders (Linyphiidae, Lycosidae), beetles (Carabidae, Staphylinidae) and hymenopterans (Scelionidae) were significantly more abundant in the cover-sown plots. Ants and collembola had a significantly higher abundance in the control plots. Some of these groups arthropods (ants and spiders), are represented by species that may commute between ground and pear trees, having an impact on pest control. The use of cover crops is encouraged to enhance biodiversity in farmlands.

Insectivorous bats selectively source moths and eat mostly pest insects on dryland and irrigated cotton farms.

Insectivorous bats are efficient predators of pest arthropods in agroecosystems. This pest control service has been estimated to be worth billions of dollars to agriculture globally. However, few studies have explicitly investigated the composition and abundance of dietary prey items consumed or assessed the ratio of pest and beneficial arthropods, making it difficult to evaluate the quality of the pest control service provided. In this study, we used metabarcoding to identify the prey items eaten by insectivorous bats over the cotton‐growing season in an intensive cropping region in northern New South Wales, Australia. We found that seven species of insectivorous bat (n = 58) consumed 728 prey species, 13 of which represented around 50% of total prey abundance consumed. Importantly, the identified prey items included major arthropod pests, comprising 65% of prey relative abundance and 13% of prey species recorded. Significant cotton pests such as Helicoverpa punctigera (Australian bollworm) and Achyra affinitalis (cotton webspinner) were detected in at least 76% of bat fecal samples, with Teleogryllus oceanicus (field crickets), Helicoverpa armigera (cotton bollworm), and Crocidosema plebejana (cotton tipworm) detected in 55% of bat fecal samples. Our results indicate that insectivorous bats are selective predators that exploit a narrow selection of preferred pest taxa and potentially play an important role in controlling lepidopteran pests on cotton farms. Our study provides crucial information for farmers to determine the service or disservice provided by insectivorous bats in relation to crops, for on‐farm decision making.

Temporal changes in the spatial distribution of carabid beetles around arable field-woodlot boundaries

Carabids are considered beneficial arthropods in agroecosystems, where they prey on crop pests or consume weed seeds. Therefore, knowledge of the spatial distribution of carabids in agricultural landscapes is crucial to efficiently manage the ecosystem services that they provide. In the present study, we investigated the spatial distribution of carabids around arable field-woodlot boundaries in different seasons: (1) early spring, (2) late spring, (3) summer and (4) late autumn. The spatial distribution of carabid abundance (activity-density) and species richness varied seasonally, and the total abundance was highest within arable fields, except in early spring when it peaked at the boundaries. The observed pattern was mainly driven by the spatial distribution of the open-habitat species, which aggregated near the field boundaries during winter and early spring. The open-habitat species penetrated into woodlots during the summer season but occurred almost exclusively outside woodlots in the other sampling periods. The abundance of the forest species was highest within woodlots with the exception of the early spring season, when their abundance peaked at the boundaries. Carabid species richness was highest within arable fields in close proximity to woodlot boundaries with the exception of the summer season, when the total species richness was similar across habitats.

Sown wildflower strips as overwintering habitat for arthropods: Effective measure or ecological trap?

Wildflower strips (WFS) are increasingly commonly adopted measures to promote biodiversity in agro-ecosystems. While their effectiveness in providing floral and other food resources for pollinators and natural enemies has been relatively well studied, much less is known about the value of different types of WFS as overwintering habitat for different functional arthropod groups. Here, we examined arthropod overwintering in WFS of different age compared to winter wheat fields. Moreover, we addressed the largely unexplored question to what extent non-permanent WFS may act as sink or ecological trap, if they attract high numbers of overwintering arthropods but only a low proportion of them survive and successfully emerge due to ploughing of strips during overwintering.Overwintering of all studied arthropod groups including potential pest natural enemies spiders, carabid beetles, staphylinid beetles and different families of pollinating flies was higher in WFS compared to winter wheat crops. Overwintering increased in WFS compared to wheat fields irrespective of WFS age, except for 4 year old WFS in the case of carabid beetles and 1 year old WFS in the case of spiders. While WFS age positively affected spider overwintering, numbers of overwintering pollinating flies and staphylinid beetles did not change significantly with WFS age. Moreover, carabid beetles tended to decline in the four years old WFS compared to younger ones. Ploughing of annual WFS during overwintering significantly reduced the number of successfully emerging arthropods by 59% on average. Detrimental effects were strongest for carabid beetles and spiders (reductions by 67% and 69%, respectively) to their numbers in ploughed WFS being similar to winter wheat fields. Reductions were less severe for pollinating flies and staphylinid beetles (both 47%), with higher numbers emerging from annual WFS compared to winter wheat fields even after ploughing of WFS.We conclude that perennial WFS are valuable overwintering habitats for a range of arthropod taxa across functional groups in arable cropping systems. Distinct responses of different arthropod taxa to WFS age highlight the importance of managing perennial WFS of various successional stages in order to promote overwintering of a broad variety arthropods in agro-ecosystems. Our study raises concerns, however, that annual WFS ploughed during the overwintering period are poor overwintering habitats for arthropods and may even act as ecological traps.

Transfer and biological effects of arsenate from soil through a plant-aphid system to the parasitoid wasp, Aphidius colemani

The accumulation of metalloid elements during transfer from contaminated soil to higher trophic levels may potentially result in the exposure of parasitic arthropods to toxic concentrations of these elements. This study examined the transfer of arsenate (As(V)) to aphids (Myzus persicae) from pepper plants cultivated in As(V) contaminated soils of two concentrations (2 and 6 mg As(V)/kg dry soil), and the subsequent biological effects on the aphid parasitoid, Aphidius colemani. Results showed that considerable quantities of As(V) were transferred to the plant in a concentration-dependent manner and were partitioned in the plant parts in the order of roots > stems > leaves. The accumulation of As(V) in the aphids increased with the concentrations in the plants; however, the transfer coefficient of As(V) from leaf to aphid was relatively similar and constant (0.07–0.08) at both soil As(V) concentration levels. Increased levels of As(V) significantly affected fecundity and honeydew production in aphids, but survival and developmental time were unaffected. Fecundity (mummification rate) of the parasitoid was not impaired by host As(V) contamination; however, vitality (eclosion rate) was significantly affected. Results are discussed in relation to possible ecological risks posed by the transfer of soil As(V) via the plant-arthropod system to parasitoid arthropods in agroecosystems.

Soil tillage reduces arthropod biodiversity and has lag effects within organic and conventional crop rotations

AbstractCrop rotation systems in organic and conventional farming systems differ in crop types, management and duration. However, changes in arthropod communities over the entire rotation system are poorly understood, as many studies have surveyed only single years or have not covered the entire rotation period. Here, we describe changes in arthropods in two contrasting systems at a split organic‐conventional farm: an 8‐year organically managed rotation with five crops and a 5‐year conventionally managed rotation with three crops. Arthropods were classified into three functional groups, representing epigeal predators, foliar predators/parasitoids and herbivores/pollinators. Epigeal predators were particularly reduced by soil tillage which occurred annually in the conventional rotation, but was intermittent in the organic. Arthropods were most abundant on the conventional rotation, but most taxonomically diverse on the organic. In the conventional system, all functional groups showed a cyclical change in their taxonomic composition that closely matched the crop rotation sequence, whereas in the organic rotation, the cycle was less clear. Whilst the current year's crop type was the major determinant of arthropod community composition, there was a significant “lag effect” for many taxa from the preceding year's crop. Our results suggest that both the amounts of soil tillage (e.g., in no‐till systems) and crop rotation order have major impacts on arthropods in agroecosystems. Rotations with excessive soil tillage are likely to reduce the abundance of some groups of beneficial arthropods, especially epigeal predators.

A Review of Sampling and Monitoring Methods for Beneficial Arthropods in Agroecosystems.

Beneficial arthropods provide many important ecosystem services. In agroecosystems, pollination and control of crop pests provide benefits worth billions of dollars annually. Effective sampling and monitoring of these beneficial arthropods is essential for ensuring their short- and long-term viability and effectiveness. There are numerous methods available for sampling beneficial arthropods in a variety of habitats, and these methods can vary in efficiency and effectiveness. In this paper I review active and passive sampling methods for non-Apis bees and arthropod natural enemies of agricultural pests, including methods for sampling flying insects, arthropods on vegetation and in soil and litter environments, and estimation of predation and parasitism rates. Sample sizes, lethal sampling, and the potential usefulness of bycatch are also discussed.

Conserving Phytophagous Arthropods to Conserve Natural Enemies:Asclepias curassavicaas the Model

To understand the entomofauna and potential as alternate hosts for natural enemies of Asclepias curassavica L., a study was established between 2012 and 2013 at Emiliano Zapata, Villamar, Michoacan, Mexico. Fifty plants of A. curassavica were planted in pots, and phytophagous arthropods, predators, parasitoids, and aphid parasitism were sampled and recorded each week. Ten species of phytophagous arthropods were identified, including Aphis nerii B. de F., Danaus plexippus L, Oncopeltus fasciatus Dallas, Lygaeus reclivatus Say, and Liriomyza asclepiadis Spencer. Seven species of parasitoids and 14 predators were recorded. Trichogramma pretiosum Riley was an important parasitoid in eggs of D. plexippus, while Lysiphlebus testaceipes (Cresson) was the most important parasitoid in A. nerii. The most important predators were Pseudodorus clavatus (Fabricius), Leucopis sp. (both 14.97%), Chrysopidae (21.43%), and Coccinellidae families; Cicloneda sanguinea L. (55.22%) and Scymnus sp. (3.84%) were the most important species. Holobus sp. preyed on the phytophagous mite, Eotetranychus typhae Tuttle, Baker and Abbatiello. E. typhae was recorded for the first time on A. curassavica. The wide diversity of natural enemies associated with specialized phytophagous arthropods of A. curassavica suggested potential of the plant to be deliberately used as a reservoir of alternate hosts of natural enemies, which could eventually regulate abundance of arthropods in agro-ecosystems.

Seven newly recorded species and families of spiders from Reunion Island (Malagasy region) (Araneae, Araneomorphae)

To date, 24 spider families have been identified on Reunion Island. But published data on spider fauna mainly concerned natural habitats and highlands. Studies of predatory arthropods in agroecosystems provided the opportunity to conduct a thorough investigation of spider diversity. Seven species and families of spiders are newly recorded for Reunion Island: Creugas gulosus Thorell, 1878 (Corinnidae), Oedignatha scrobiculata Thorell, 1881 (Liocranidae), Ero aphana (Walckenaer, 1802) (Mimetidae), Palicanus caudatus Thorell, 1897 (Miturgidae), Oecobius marathaus Tikader, 1962 (Oecobiidae) and Orthobula impressa Simon, 1897 (Phrurolithidae) and Tropizodium peregrinum Jocque & Churchill, 2005 (Zodariidae). (Resume d'auteur)

Future rainfall variations reduce abundances of aboveground arthropods in model agroecosystems with different soil types

Climate change scenarios for Central Europe predict less frequent but heavier rainfalls and longer drought periods during the growing season. This is expected to alter arthropods in agroecosystems that are important as biocontrol agents, herbivores or food for predators (e.g. farmland birds). In a lysimeter facility (totally 18 3-m2-plots), we experimentally tested the effects of long-term past vs. prognosticated future rainfall variations (15% increased rainfall per event, 25% more dry days) according to regionalized climate change models from the Intergovernmental Panel on Climate Change (IPCC) on aboveground arthropods in winter wheat (Triticum aestivum L.) cultivated at three different soil types (calcaric phaeozem, calcic chernozem and gleyic phaeozem). Soil types were established 17 years and rainfall treatments one month before arthropod sampling; treatments were fully crossed and replicated three times. Aboveground arthropods were assessed by suction sampling, their mean abundances (± SD) differed between April, May and June with 20 ± 3 m-2, 90 ± 35 m-2 and 289 ± 93 individuals m-2, respectively. Averaged across sampling dates, future rainfall reduced the abundance of spiders (Araneae, -47%), cicadas and leafhoppers (Auchenorrhyncha, -39%), beetles (Coleoptera, -52%), ground beetles (Carabidae, -41%), leaf beetles (Chrysomelidae, -64%), spring tails (Collembola, -58%), flies (Diptera, -73%) and lacewings (Neuroptera, -73%) but increased the abundance of snails (Gastropoda, +69%). Across sampling dates, soil types had no effects on arthropod abundances. Arthropod diversity was neither affected by rainfall nor soil types. Arthropod abundance was positively correlated with weed biomass for almost all taxa; abundance of Hemiptera and of total arthropods was positively correlated with weed density. These detrimental effects of future rainfall varieties on arthropod taxa in wheat fields can potentially alter arthropod-associated agroecosystem services.

Functional biodiversity in the agricultural landscape: relationships between weeds and arthropod fauna

Bàrberi P, Burgio G, Dinelli G, Moonen AC, Otto S, Vazzana C & Zanin G (2010). Functional biodiversity in the agricultural landscape: relationships between weeds and arthropod fauna. Weed Research50, 388–401.SummaryWe reviewed studies aimed at understanding functional relationships between weeds and arthropods in agroecosystems as influenced by biodiversity at different scales, with the main goal of highlighting gaps in knowledge, research methods and approaches. We first addressed: (i) the regulation of arthropod communities by weed diversity at genetic, species and habitat levels, (ii) the regulation of weed communities by arthropods through seed predation and dispersal and (iii) below‐ground weed‐insect interactions. We then focussed on methodologies to study weed–arthropod interactions in agricultural landscapes and discuss techniques potentially available for data analysis and the importance of joint weed–arthropod trend detection. Lastly, we discuss the implications of research findings for biodiversity conservation policies (agri‐environmental schemes) and suggest some priorities for future work. Results showed that to date research has largely ignored weed–arthropod interactions in agricultural landscapes. No information is available on the role of weed genetic diversity as driver of weed–arthropod interactions, whereas studies on effects of species and habitat diversity often lack a functional perspective and/or a spatial component. Also, information on how management of the wider agricultural biotope might express positive weed–arthropod functional interactions is scarce. Another area worth being explored is the relationship between weed‐leaf/root herbivores and beneficial arthropods. Tools for spatial data analysis might be useful for elucidating weed–arthropod interactions in agricultural landscapes, but some methodological aspects, e.g. the definition of the most appropriate experimental design and sampling scale/frequency, must be refined. New studies on weed–arthropod interactions should encompass an explicit spatial component; this knowledge is particularly important for improving IPM/IWM systems and designing more targeted agri‐environmental schemes.

Exposure to a glyphosate-based herbicide affects agrobiont predatory arthropod behaviour and long-term survival

Humans commonly apply chemicals to manage agroecosystems. If those chemicals influence the behaviour or survival of non-target arthropods, the food web could be altered in unintended ways. Glyphosate-based herbicides are among the most ubiquitous pesticides used around the world, yet little is known about if and how they might affect the success of terrestrial predatory arthropods in agroecosystems. In this study, we quantified the effects of a commercial formulation of a glyphosate-based herbicide on the activity of three predatory arthropod species that inhabit agricultural fields in the eastern United States. We also measured the survival of the most common species. We tested the reactions of the wolf spider, Pardosa milvina, to either direct application (topical) or contact with a treated substrate (residual). We quantified the reactions of a larger wolf spider, Hogna helluo, and a ground beetle, Scarites quadriceps, to a compound (topical plus residual) exposure. Pardosa milvina reduced locomotion time and distance under topical herbicide exposure, but increased speed and non-locomotory activity time on exposed substrate. Both H. helluo and S. quadriceps increased non-locomotory activity time under compound herbicide exposure. Over a period of 60 days post-exposure, residually exposed P. milvina exhibited lower survivorship compared to topically exposed and control groups. Thus, exposure of terrestrial arthropods to glyphosate-based herbicides affects their behaviour and long-term survival. These results suggest that herbicides can affect arthropod community dynamics separate from their impact on the plant community and may influence biological control in agroecosystems.

Aged pesticide residues are detrimental to agrobiont spiders (Araneae)

AbstractSpiders are among the most abundant arthropods in agroecosystems, playing an important role as natural enemies of various pests. In this study we evaluated residual activity of selected pesticides on the mortality and behaviour of four spider species (Dictyna uncinata, Pardosa palustris, Philodromus cespitum and Theridion impressum). We used three pesticides: a herbicide Command (clomazone), and insecticides Decis (deltamethrin) and Nurelle (chlorpyrifos and cypermethrin). Mortality was recorded after exposure of spiders to fresh (2‐h), 5, 10, 15 and 20‐day‐old residues. For each residue mortality was evaluated after 24–72 h. Residual effect differed between preparations and, in some cases, between spiders. All of the Nurelle residues (fresh to 20‐day‐old) caused 100% mortality in all spider species. Residues of Command were rather harmless (causing <20% mortality) to all spider species as the herbicide activity declined with age. Residues of Decis had species‐specific effects as the mortality varied between 0 and 90%. In Dictyna the mortality gradually declined with the age of residues, while in Pardosa the mortality increased. In Philodromus and Theridion the mortality declined up to 10‐day‐old residues and then increased so that 20‐day‐old residues caused almost as high mortality as the new ones. Exposure to pesticide residues immediately affected the movement of Pardosa spiders. Residues of Decis and Nurelle decreased spider locomotion, while those of Command increased locomotion in comparison with the control. In another experiment, we studied repellence of fresh pesticide residues to Pardosa spiders. In comparison with the control, spiders stayed a similar time on the surface treated with Command, but four times less on Decis and nine times less on Nurelle‐treated surfaces, respectively. In conclusion, aged insecticide residues possess a high activity and can cause long‐term decline in the abundance and prolonged behavioural disturbance of spiders in agroecosystems.

The role of hedgerows in the recolonisation of arable fields by epigeal Collembola

Summary The role of hedgerows as reservoirs for beneficial arthropods in agroecosystems has been extensively studied, but their importance as habitats for springtails (Collembola) is largely unknown. Population recovery in arable fields by epigeal Collembola can occur either from population sources in non-crop habitats or in-situ reproduction of field-dwelling species. In this study we investigated the recovery of springtail populations in a spring-sown cereal crop following a physical disturbance due to tillage. To investigate the role of a hedgerow in population recovery, replicated lengths of hedgerow were isolated from the field using exclusion barriers. Some species of Collembola (e.g. Isotomurus spp., Bourletiella hortensis) were consistently more abundant next to the hedgerow than within the field. Areas of the field adjacent to barriered sections of hedgerow developed significantly different populations and community structures compared to unbarriered ‘controls’. Abundance of several species in the field (e.g. Isotoma viridis, Sminthurinus elegans, Sminthurus viridis) was reduced by hedgerow barriers, providing the first evidence that hedgerows could be important source habitats for the colonisation or recolonisation of arable fields by Collembola.

Diurnal activity of soil-surface arthropods in agroecosystems: Design for an inexpensive time-sorting pitfall trap

The design for an inexpensive time-sorting pitfall trap is presented. The basis of the mechanism is a rotary stepping solenoid powered by lantern batteries. Traps were utilized to sample soil-surface arthropods at 2-h intervals for five 24-h periods in 1983. One trap was placed in a conventional tillage (CT) agroecosystem and one in a no-tillage (NT) agroecosystem. Soil arthropod surface activity was greatest in CT on 19 July during the dawn and dusk periods and during dusk on 27 June.