Aboveground Arthropods Research Articles

Temporal variation of soil microarthropods in different forest types and regions of central Europe

Biodiversity and biomass of aboveground arthropods in central European forests continuously declined during the last decade. However, whether belowground microarthropod communities follow similar patterns has not been investigated. In this study, we compared the abundance, diversity, community composition, stability and asynchrony of oribatid mites (Acari: Oribatida) sampled in four forest types of increasing management intensity (unmanaged beech, old managed beech, young managed beech, and coniferous) at three‐year intervals from 2008 to 2020. Forest sites were replicated in three regions in southern, central and northern Germany, i.e. the Swabian Alb, Hainich‐Dün and the Schorfheide Chorin, which differ in soil characteristics and climate. We found 25 152 individuals and 121 species of oribatid mites and detected no linear decline in abundance and diversity over the last decade, suggesting that microarthropods in forest soils are buffered against land‐use effects. However, we observed that years with low winter precipitation in regions with soils that are prone to drought, resulted in significant decreases in oribatid mite densities. Community compositions remained similar across sampling years, but differed between regions and forest types, predominantly due to differences in the proportion of asexual individuals. The stability of oribatid mite communities did not decrease in managed forests and was highest in deep soils with high water‐holding capacity, which may reduce temporal variation, suggesting that soil properties are more important for the stability of oribatid mite communities than forest management. However, stability patterns were not explained by asynchrony in species fluctuations, as all communities either showed a high degree of synchrony or were not different from random. Our study highlights that the temporal dynamics of belowground communities may differ from those aboveground, and that regional differences in precipitation and soil properties are more important than forest types.

Differential effects of soil conservation practices on arthropods and crop yields

AbstractMany agricultural management tactics, such as reduced tillage, aim to promote biodiversity and ecosystem services. Responses to such tactics can be context dependent, however, and differentially impact (i) functional groups of service‐providing organisms and (ii) crop yields. In canola (Brassica napus L., B. rapa L.) crop fields, we assessed how soil tillage and landscape context (amount of semi‐natural habitat within 1 km of each field) affected arthropod biodiversity and crop yield. We assessed effects of full (multiple tillage passes that leave soil surface bare), intermediate (tilled once and some stubble remains), or no (seed planted directly into last year's stubble) tillage on functional groups with unique diets and reproductive strategies: (i) herbivores, (ii) kleptoparasites, (iii) parasitoids, (iv) pollinators, and (v) predators. Effects of tillage and landscape context on arthropod abundance and diversity varied across functional groups. Pollinators responded strongest to tillage, benefitting from intermediate tillage. Predators and herbivores responded strongly to landscape context, as both were more abundant in landscapes with more semi‐natural habitat. Our results suggest that natural history differences among functional groups mediate effects of landscape context on biodiversity. However, variation in arthropod communities had little effect on canola crop yield. The effects of soil management practices on aboveground arthropods are complex, and practices thought to increase some aspects of agricultural sustainability may not be beneficial in other contexts. Identifying practices such as intermediate tillage that may increase soil quality and arthropod diversity is a key to designing agricultural ecosystems that will effectively benefit both biodiversity and human well‐being.

The global biomass and number of terrestrial arthropods.

Insects and other arthropods are central to terrestrial ecosystems. However, data are lacking regarding their global population abundance. We synthesized thousands of evaluations from around 500 sites worldwide, estimating the absolute biomass and abundance of terrestrial arthropods across different taxa and habitats. We found that there are ≈1 × 1019 (twofold uncertainty range) soil arthropods on Earth, ≈95% of which are soil mites and springtails. The soil contains ≈200 (twofold uncertainty range) million metric tons (Mt) of dry biomass. Termites contribute ≈40% of the soil biomass, much more than ants at ≈10%. Our estimate for the global biomass of above-ground arthropods is more uncertain, highlighting a knowledge gap that future research should aim to close. We estimate the combined dry biomass of all terrestrial arthropods at ≈300 Mt (uncertainty range, 100 to 500), similar to the mass of humanity and its livestock. These estimates enhance the quantitative understanding of arthropods in terrestrial ecosystems and provide an initial holistic benchmark on their decline.

Organic rice cultivation enhances the diversity of above-ground arthropods but not below-ground soil eukaryotes

Organic farming generally has greater biodiversity compared to conventional farming. However, few studies have examined both above- and below-ground biodiversity in organic farming of the rice field, and little is known about whether and how biodiversity is affected by the duration of organic farming. In this study, we conducted a two-year investigation on one conventional farm, as well as two organic farms with different management durations (1 and 5 years before sampling). Compared to conventional farming, species richness increased by 40% for arthropods in organic farming, with 75% for pests and 35% for natural enemies, but there were no differences for soil microbial eukaryotes. No significant difference in species diversity of arthropods and soil microbial eukaryotes was found between two organic farms, which may indicate that five years is not yet long enough to achieve significant changes in arthropod and eukaryotic communities. We used a compatibility index (Cc-o) to evaluate the trade-off between biodiversity, rice yield, and economic benefits of conversion from conventional to organic farming. Results showed that the yield-based value of Cc-o was close to 0 for above-ground arthropods and negative for soil eukaryotes. However, Cc-o values based on economic benefits were positive for all taxa. Our study indicates that both one year and five years durations of organic farming could improve the diversity of above-ground arthropods, but not that of below-ground soil eukaryotes in the rice field. There was an equivalent gain in biodiversity and loss in yield for above-ground arthropods under organic farming, but win-win scenarios may occur when the economic benefits are considered.

Digging Deeper into the Ecology of Subterranean Ants: Diversity and Niche Partitioning across Two Continents

Soil fauna is generally understudied compared to above-ground arthropods, and ants are no exception. Here, we compared a primary and a secondary forest each on two continents using four different sampling methods. Winkler sampling, pitfalls, and four types of above- and below-ground baits (dead, crushed insects; melezitose; living termites; living mealworms/grasshoppers) were applied on four plots (4 × 4 grid points) on each site. Although less diverse than Winkler samples and pitfalls, subterranean baits provided a remarkable ant community. Our baiting system provided a large dataset to systematically quantify strata and dietary specialisation in tropical rainforest ants. Compared to above-ground baits, 10–28% of the species at subterranean baits were overall more common (or unique to) below ground, indicating a fauna that was truly specialised to this stratum. Species turnover was particularly high in the primary forests, both concerning above-ground and subterranean baits and between grid points within a site. This suggests that secondary forests are more impoverished, especially concerning their subterranean fauna. Although subterranean ants rarely displayed specific preferences for a bait type, they were in general more specialised than above-ground ants; this was true for entire communities, but also for the same species if they foraged in both strata.

Influences of soil creatures toward aboveground Arthropods in environmentally friendly rice field

Environmentally friendly farming is the most encouraging approach to beat the negative impacts of conventional farming on the ecosystem. To determine the effect of different histories of environmentally friendly rice fields on the interaction between soil creatures and biodiversity of aboveground arthropods, the researchers conducted studies in 5 and 20 years old of environmentally friendly rice fields. The investigation was conducted to find out the impacts of soil creatures on the number of aboveground arthropods by estimating the activity of soil creatures, nutrient contents, and abundance of arthropods. The research was hypothesized that long histories of living matters in the environmentally friendly rice field are supposed to rise soil microbial denitrification and N immobilization, adequately increment the plant N contents and arthropods abundance. The results showed that 20 years of environmentally friendly rice fields improved the abundance of soil creatures, biomass of soil microbial C and N, soil nutrition, and these effects indirectly improved the abundance of aboveground arthropods. This investigation recommends that environmentally friendly rice fields improve the interactions among soil creatures and the aboveground ecological community accordingly may accomplish supportability of the rice field framework.

Risk assessment of genetically engineered rice Bt-9 resistant to Cnaphalocrocis medinalis: influence on above-ground arthropods in Korea

Risk assessment of genetically engineered rice Bt-9 resistant to Cnaphalocrocis medinalis: influence on above-ground arthropods in Korea

Reducing Fertilizer and Avoiding Herbicides in Oil Palm Plantations—Ecological and Economic Valuations

Oil palm plantations are intensively managed agricultural systems that increasingly dominate certain tropical regions. Oil palm monocultures have been criticized because of their reduced biodiversity compared to the forests they historically replaced, and because of their negative impact on soils, water, and climate. We experimentally test whether less intensive management schemes may enhance biodiversity and lessen detrimental effects on the environment while maintaining high yields. We compare reduced versus conventional fertilization, as well as mechanical versus chemical weed control (with herbicides) in a long-term, full-factorial, multidisciplinary experiment. We conducted the experiment in an oil palm company estate in Sumatra, Indonesia, and report the results of the first two years. We measured soil nutrients and functions, surveyed above- and below-ground organisms, tracked oil palm condition and productivity, and calculated plantation gross margins. Plants, aboveground arthropods and belowground animals were positively affected by mechanical versus chemical weed control, but we could not detect effects on birds and bats. There were no detectable negative effects of reduced fertilization or mechanical weeding on oil palm yields, fine roots, or leaf area index; however, stem growth was enhanced under mechanical weeding. Also, we could not detect detrimental effects of the reduced fertilization and mechanical weeding on soil nutrients and functions (mineral nitrogen, bulk density, and litter decomposition), but water infiltration and base saturation tended to be higher under mechanical weeding, while soil moisture and microbial biomass varied with treatment. Economic performance, measured as gross margins, was higher under reduced fertilization. There might be a delayed response of oil palm to the different management schemes applied, so results of future years may confirm whether this is a sustainable management strategy. Nevertheless, the initial effects of the experiment are encouraging to consider less intensive management practices as economically and ecologically viable options for oil palm plantations.

Honeybush (Cyclopia spp.) phenology and associated arthropod diversity in the Overberg region, South Africa

Background: Cyclopia is endemic to regions of the Cape Floristic Region across the Eastern and Western Cape provinces of South Africa and is commonly known as honeybush. Honeybush has historically been used as an herbal tea, and has proven medicinal properties. Honeybush biomass and extracts are used in the functional foods and cosmetics sectors, both locally and overseas. The growing demand for honeybush calls for increased agricultural production and a shift away from the predominantly wild harvested supply.Objectives: The current study aimed to address the lack of baseline knowledge on honeybush phenology and its associated arthropod community to advance sustainable production of commercially valued plants in the genus.Method: The study was conducted on wild and cultivated Cyclopia species (Cyclopia maculata and Cyclopia genistoides) at respective sites in the Overberg region. Sampling took place from April 2014 to April 2015 using qualitative methods for recording seasonal honeybush phenology and suction sampling for aboveground arthropods. Focal insect taxa (Coleoptera, Hemiptera, Thysanoptera, Lepidoptera and Hymenoptera) were sorted and identified to family level and classified into functional feeding guilds.Results: Qualitative phenology observations of wild C. maculata and cultivated C. genistoides indicated a high level of congruency in seasonality of phenophase stages. Associated arthropod assemblages contained a diversity of families per functional feeding group, namely phytophagous, zoophagous and omnivorous taxa, with high seasonal variability.Conclusion: Findings highlight the complexity of ecological elements to be taken into consideration for ecologically sound honeybush cultivation. Outcomes can be applied to land management practices and governance policies promoting sustainable agroecosystems in honeybush production areas.

Abundance of arthropods as food for meadow bird chicks in response to short- and long-term soil wetting in Dutch dairy grasslands.

BackgroundThroughout the world, intensive dairy farming has resulted in grasslands almost devoid of arthropods and birds. Meadow birds appear to be especially vulnerable during the chick-rearing period. So far, studies have focused mainly on describing population declines, but solutions to effectively stop these trends on the short-term are lacking. In this study at a single farm, we experimentally manipulated soil moisture through occasional irrigation, to mitigate against early season drainage and create favorable conditions for the emergence of above-ground arthropods during the meadow bird chick rearing phase.MethodsTo guarantee the presence of at least a sizeable arthropod community for the measurement of effects of wetting, we selected a farm with low intensity management. The land use and intensity of the study site and surroundings were categorized according to the national land use database and quantified using remote sensing imagery. From May 1 to June 18, 2017, we compared a control situation, with no water added, to two wetting treatments, a “short-term” (3 weeks) treatment based on wetting on warm days with a sprinkler system and a “long-term” treatment next to a water pond with a consistently raised water table from 2010. We measured soil temperature, soil moisture and resistance as well as the biomass of arthropods at 3-day intervals. Flying arthropods were sampled by sticky traps and crawling arthropods by pitfall traps. Individual arthropods were identified to Order and their length recorded, to assess their relevance to meadow bird chicks.ResultsThe land use analysis confirmed that the selected dairy farm had very low intensity management. This was different from most of the surrounding area (20 km radius), characterized by (very) high intensity land use. The experiments showed that irrigation contributed to cooler soils during midday, and that his happened already in the early part of the season; the differences with the control increased with time. In the short- and long-term treatments, soil moisture increased and soil resistance decreased from the mid-measurement period onward. Compared with the control, cumulative arthropod biomass was higher in the long-term treatment, but showed no change in the irrigation treatment. We conclude that small-scale interventions, such as occasional irrigation, favorably affected local soil properties. However, the effects on above-ground arthropod abundance currently appear limited or overridden by negative landscape-scale processes on arthropods.

Crop identity and memory effects on aboveground arthropods in a long-term crop rotation experiment.

Agricultural landscapes are globally dominated by monocultures under intensive management. This is one of the main reasons for biodiversity loss and insect population decline in many regions all over the world. Agroecosystem biodiversity in these areas can be enhanced by cropping system diversification, such as crop rotations. Yet, long‐term studies on effects of crop rotations on aboveground agrobiodiversity are lacking. We set up a 10‐year long‐term crop rotation experiment in Central Germany and monitored the temporal dynamics of aboveground arthropods over a full cultivation period to investigate influence of current and preceding crop identity and cropping system diversification on activity density, species richness, and community structure. We found that species composition was strongly influenced by currently grown crop although effect on arthropods varied between species groups. Especially, winter oilseed rape strongly affects arthropod community structure. Interestingly, we were also able to show an influence of the preceding crops, indicating an ecological memory effect in the aboveground arthropod community. Our results show that crop identity of both currently and previously grown crops in crop rotations may lead to an increase in arthropod activity density and changes in species composition. Diversified crop rotations including appropriate crops can be an easily implemented tool to increase arthropod biodiversity and biomass at large spatial and temporal scales, particularly in areas dominated by a single crop (e.g., wheat, maize). Our results may help to design optimized crop rotations for large‐scale enhancement of insect biodiversity in agroecosystems.

Diversity, spatial and temporal distribution of aboveground arthropods associated with watermelon in the Nigerian southern guinea savanna

Diversity, spatial and temporal distribution of aboveground arthropods associated with watermelon in the Nigerian southern guinea savanna

Diversity, spatial and temporal distribution of above-ground arthropods associated with watermelon in the Nigerian southern guinea savanna

Diversity, spatial and temporal distribution of above-ground arthropods associated with watermelon in the Nigerian southern guinea savanna

Diversity, spatial and temporal distribution of above-ground arthropods associated with watermelon in the Nigerian southern guinea savanna

Diversity, spatial and temporal distribution of above-ground arthropods associated with watermelon in the Nigerian southern guinea savanna

Positive effects of wheat variety mixtures on aboveground arthropods are weak and variable

Although modern agriculture generally relies on homogeneous varieties that are usually grown in pure stands, crop variety mixtures have been used for a long time, notably to improve resistance to fungal diseases. A growing number of studies suggest that intraspecific plant diversity may also enhance the abundance and diversity of wild species and thereby some ecosystem services such as biological control by natural predators. However, positive effects of the genetic diversity of plant species on the diversity of associated communities have mostly been documented in natural systems, with only a handful of studies targeting crop species in agroecosystems. Here, we investigated the ecological effects of the number of winter wheat varieties (Triticum aestivum) on aboveground arthropods and particularly predatory species. We manipulated the number of wheat varieties (1, 2, 4 or 8) in 120 plots (80m2 each) to examine how wheat diversity and stand characteristics impact communities of three dominant aboveground arthropod groups that include many predatory species: ground beetles, rove beetles and spiders. The number of wheat varieties had a weak, but positive effect on predator abundance, notably spider abundance. In contrast, wheat functional diversity, as assessed by the number of wheat functional groups, was only negatively related to the diversity of spiders. Among wheat stand characteristics, the variance in plant height, wheat biomass and the Green Area Index were weakly correlated with ground beetle, rove beetle and predatory diversity, respectively. The Green Area Index was also weakly correlated with ground beetle abundance. Our study suggests that wheat variety mixtures have variable and limited effects on aboveground arthropods and probably low effectiveness to enhance biological control, but these results should be further tested under low-input agriculture in real fields.

耕作方式对玉-豆轮作地表节肢动物多样性及其营养结构的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 耕作方式对玉-豆轮作地表节肢动物多样性及其营养结构的影响 DOI: 10.5846/stxb201709221712 作者: 作者单位: 中国科学院东北地理与农业生态研究所,吉林大学;吉林大学,商丘师范学院,中国科学院东北地理与农业生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41501263，41430857）；中国博士后科学基金面上项目（2016M590269）；河南省科技厅科技攻关项目（172102410054）；商丘师范学院骨干教师项目（2015GGJS15）；2014年河南省哲学社会科学规划项目（2014CJJ087） Response of ground-dwelling arthropod community diversity and its trophic structure in relation tillage regimes under maize-soybean rotation Author: Affiliation: College of Surveying and Planning,Shangqiu Normal University,,,Northeast Institute of Geography and Agroecology 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:为阐明长期不同耕作方式对轮作种植模式黑土农田地表节肢动物多样性及其营养结构的影响，2015年5月至9月间，利用陷阱法对连续13年玉米大豆轮作模式的定位试验站三种耕作方式（免耕、垄作、秋翻）的地表节肢动物群落进行了调查。共捕获动物1002只，隶属于3纲11目29科37个类群，凹唇蚁、玉米毛蚁和直角通缘步甲为优势类群。免耕（NT，no tillage）有利于增加蜘蛛类群密度，垄作（RT，ridge tillage）和秋翻（MP，mould board plough）显著增加了玉米毛蚁密度。耕作方式仅对群落密度有显著影响显著影响（P < 0.05），而大豆不同生育阶段显著或极显著的影响地表节肢动物群落组成特征（P < 0.05；P < 0.001）。长期玉米大豆轮作种植的地表节肢动物群落营养功能群在不同耕作方式中所占比例不同，保护性耕作方式（NT、RT）更有利于捕食性和植食性动物的生存和繁殖，常规耕作（MP）则是杂食性动物占据优势，明显呈现对不稳定环境的适应。大豆不同生育期，各功能群的个体数与类群数的动态变化不尽一致，不具有明显的规律性。研究结果表明，免耕轮作对维持地表节肢动物群落内部物种间的关系及其营养结构有着较为重要的作用，保护性耕作和轮作种植模式相结合可维持农田生态系统平衡。 Abstract:Conservation tillage, such as reduced tillage or no-tillage, may play an important role in increasing soil organic matter, reducing soil erosion, and providing a more complex and favorable habitat for soil-dwelling organisms. Aboveground arthropods are important components of ecosystems, promoting a number of key functions, such as decomposition of organic matter and some herbivorous pest control. The abundance and diversity of food web components depends highly on the rotation system and soil management. To reveal the effect of tillage regimes on the diversity and trophic structure of ground-dwelling arthropods under maize-soybean rotation in the black soil of Northeast China, five field investigations were conducted with three tillage regimes (no tillage, NT; ridge tillage, RT; mould board plough, MP) at a 13-year tillage regime experiment station. A total of 1002 arthropod individuals belonging to 3 classes, 11 orders, 29 families, and 37 groups were collected. Formica sanguinea Letreille, Lasius alienus Foerster, and Poecilus gebleri Dejean were the dominant species and accounted for 60.58% of the total individuals. The results showed that NT was beneficial to the spider population resulting in increased densities, and RT and MP significantly increased the density of Lasius alienus. Tillage regimes only significantly affected the density of arthropod communities in different growth stages (P < 0.05), whereas different growth stages of soybeans significantly or highly significantly affected the density, groups, and diversity of the arthropod community under different tillage regimes (P < 0.05; P < 0.001). In the long-term, under the maize and soybean rotation system, the proportion of trophic functional groups was different under the different tillage practices. The results indicated that the long-term conservation tillage (NT and RT) was more conducive to the survival of predators and herbivorous arthropods. Omnivores were dominant in the MP system, showing obvious adaptation to the unstable environment. In the different growth stages of the soybeans, the variation in all functional groups was not consistent, and there was no obvious pattern. It is obvious that no-tillage with rotation play an important role in maintaining the relationship between the species within the community and the trophic structure of the food web. 参考文献 相似文献 引证文献

Land‐use type and intensity differentially filter traits in above‐ and below‐ground arthropod communities

Along with the global decline of species richness goes a loss of ecological traits. Associated biotic homogenization of animal communities and narrowing of trait diversity threaten ecosystem functioning and human well-being. High management intensity is regarded as an important ecological filter, eliminating species that lack suitable adaptations. Below-ground arthropods are assumed to be less sensitive to such effects than above-ground arthropods. Here, we compared the impact of management intensity between (grassland vs. forest) and within land-use types (local management intensity) on the trait diversity and composition in below- and above-ground arthropod communities. We used data on 722 arthropod species living above-ground (Auchenorrhyncha and Heteroptera), primarily in soil (Chilopoda and Oribatida) or at the interface (Araneae and Carabidae). Our results show that trait diversity of arthropod communities is not primarily reduced by intense local land use, but is rather affected by differences between land-use types. Communities of Auchenorrhyncha and Chilopoda had significantly lower trait diversity in grassland habitats as compared to forests. Carabidae showed the opposite pattern with higher trait diversity in grasslands. Grasslands had a lower proportion of large Auchenorrhyncha and Carabidae individuals, whereas Chilopoda and Heteroptera individuals were larger in grasslands. Body size decreased with land-use intensity across taxa, but only in grasslands. The proportion of individuals with low mobility declined with land-use intensity in Araneae and Auchenorrhyncha, but increased in Chilopoda and grassland Heteroptera. The proportion of carnivorous individuals increased with land-use intensity in Heteroptera in forests and in Oribatida and Carabidae in grasslands. Our results suggest that gradients in management intensity across land-use types will not generally reduce trait diversity in multiple taxa, but will exert strong trait filtering within individual taxa. The observed patterns for trait filtering in individual taxa are not related to major classifications into above- and below-ground species. Instead, ecologically different taxa resembled each other in their trait diversity and compositional responses to land-use differences. These previously undescribed patterns offer an opportunity to develop management strategies for the conservation of trait diversity across taxonomic groups in permanent grassland and forest habitats.

Arthropods and novel bird habitats: do clear-cuts in spruce plantations provide similar food resources for insectivorous birds compared with farmland habitats?

Arthropods, and insects in particular, constitute important food resources for several higher trophic levels like birds. Their abundance and diversity is likely to differ between habitat types depending on the local conditions and resources. This may have important consequences for arthropod consumers that occupy structurally different habitat types. Most bird-focused studies address, however, habitats at the structural, vegetation-based level and disregard the presence of sufficient quantities and qualities of arthropod prey items. Here, we compare the quantity and quality of ground-dwelling and above-ground arthropods as food resources for early-successional birds between two structurally different human-modified habitat types sharing similar bird assemblages: low-intensity farmland areas and plantation forest clear-cut areas in the south of Belgium. Forest clear-cut patches constitute a novel habitat for so-called ‘farmland’ birds. Our results show that arthropod abundance is substantially higher in farmland than in forest clear-cuts, although arthropods are slightly larger in clear-cuts. Higher arthropod abundance is associated with higher ground-level temperature in farmland. Although both habitat types host the same spectrum of arthropod species, forest and farmland management practices induce different conditions for food quantity and, to some extent, food quality for insectivorous birds. We discuss the mechanisms behind the observed pattern of arthropod abundance and the fitness-related consequences of contrasting food availability in farmland and forest clear-cut habitats for early-successional bird species.

Risk Assessment of Genetically Engineered Maize Resistant to Diabrotica spp.: Influence on Above-Ground Arthropods in the Czech Republic.

Transgenic maize MON88017, expressing the Cry3Bb1 toxin from Bacillus thuringiensis (Bt maize), confers resistance to corn rootworms (Diabrotica spp.) and provides tolerance to the herbicide glyphosate. However, prior to commercialization, substantial assessment of potential effects on non-target organisms within agroecosystems is required. The MON88017 event was therefore evaluated under field conditions in Southern Bohemia in 2009–2011, to detect possible impacts on the above-ground arthropod species. The study compared MON88017, its near-isogenic non-Bt hybrid DK315 (treated or not treated with the soil insecticide Dursban 10G) and two non-Bt reference hybrids (KIPOUS and PR38N86). Each hybrid was grown on five 0.5 ha plots distributed in a 14-ha field with a Latin square design. Semiquantitative ELISA was used to verify Cry3Bb1 toxin levels in the Bt maize. The species spectrum of non-target invertebrates changed during seasons and was affected by weather conditions. The thrips Frankliniella occidentalis was the most abundant species in all three successive years. The next most common species were aphids Rhopalosiphum padi and Metopolophium dirhodum. Frequently observed predators included Orius spp. and several species within the Coccinellidae. Throughout the three-year study, analysis of variance indicated some significant differences (P<0.05). Multivariate analysis showed that the abundance and diversity of plant dwelling insects was similar in maize with the same genetic background, for both Bt (MON88017) and non-Bt (DK315) untreated or insecticide treated. KIPOUS and PR38N86 showed some differences in species abundance relative to the Bt maize and its near-isogenic hybrid. However, the effect of management regime on arthropod community was insignificant and accounted only for a negligible portion of the variability.

Aboveground Arthropod Composition, Abundance and Guild Structure in Upland Rice Agro-ecosystem at Matalam, North Cotabato, Philippines

With the recent innovations in the field of ecological pest management,conservation and enhancement of biological diversity at any rice agro-ecosystemshas received considerable attention. The composition and abundance ofaboveground arthropods was assessed on upland rice fields in Matalam, NorthCotabato, Southern Mindanao, Philippines. Sampling and monitoring was doneusing malaise trapping, sweep netting and direct counting techniques. A total of29 arthropod species belonging to 21 families in nine orders were documented.The collected samples were comprised of 40% insect pests, 53% predators and7% parasitoids. The three most abundant insect pests were rice bug (Leptocorisaoratorius), rice seedling maggot (Atherigona oryzae), and pink stemborer (Sesamia inferens). The predators are dominated by lady bird beetle (Micraspis spp.), social wasp (unknown) and long-jawed spider (Tetragnatha maxillosa). Ichneumonids,Braconids and Tachinids, though in smaller numbers, were present throughoutthe cropping season. More importantly, the study reported the presence of four rice stem borer species – Scirpophaga innotta, Scirpophaga incertulas, Sesamia infere and Chilo suppressalis and two rice grain bug species – Paraeucosmetuspallicornis and Elasmolomus sordidus in Matalam. The occurrence, compositionand abundance of insect pests and associated natural enemies vary with ricegrowth and developmental stages. The negative Pearson’s correlation coefficient (r= -0.31) between the insect pests and natural enemies was attributed to effectivecultural management practices which have been developed through decades ofsubsistence upland rice farming.Keywords: Ecology, aboveground arthropods, upland rice agro-ecosystem, sampling andmonitoring, Philippines