A comunidade de pequenos mamíferos em áreas de savana metalófila e floresta ombrófila densa na Floresta Nacional de Carajás, PA: Estrutura, estratificação e impacto da mineração

Os pequenos mamíferos apresentam maior diversidade para a região Neotropical e são bons indicadores de alterações de habitats. Nós amostramos dois tipos de fitofisionomias. Os objetivos deste estudo foram avaliar a estrutura, a estratificação vertical e o impacto da mineração na comunidade de pequenos mamíferos nas áreas de Canga e Floresta. Foram amostradas seis linhas paralelas a partir da borda, em cada área. Foram instaladas 60 armadilhas intercaladas nos três estratos: solo, sub-bosque e dossel, durante seis noites consecutivas. E armadilhas de queda e interceptação, com 15 baldes em cada trilha, apenas nas áreas de Floresta. Foram amostradas uma área de cada fitofisionomia mais próxima e mais afastada do impacto, durante dois períodos chuvosos e dois secos, de 2009 a 2011. Nós encontramos diferenças muito evidentes quanto à composição e estrutura nos dois tipos de fitofisionomias amostradas: a riqueza foi maior na Floresta e a abundância total foi maior na Canga. Das 24 espécies amostradas, 15 foram registradas exclusivamente no solo, oito no solo e sub-bosque e uma (Glironia venusta) exclusivamente no dossel. Apenas Micoureus demerarae foi registrado nos três estratos e Caluromys philander apenas no sub-bosque e dossel. O efeito do impacto é muito evidente nas Florestas e menos nas Cangas. Nas Florestas, quanto mais distante do impacto, maior a riqueza e abundância de espécies. É importante a continuidade e o aprofundamento de estudos com comunidades de pequenos mamíferos na Floresta Nacional de Carajás, ampliando o conhecimento científico para propor medidas que minimizem o impacto causado pela atividade mineradora na região.

A riqueza e diversidade de anfíbios anuros da Serra do Mendanha, Estado do Rio de Janeiro, RJ: grau de conservação da floresta, variação altitudinal e uso de recursos hídricos

Os anfíbios anuros que habitam o bioma Mata Atlântica, especialmente em sua floresta ombrófila densa, são pouco conhecidos sob diversos aspectos de sua ecologia, existindo poucas informações disponíveis na literatura científica. Estes dados estão limitados a poucas localidades, geralmente estudos realizados em fragmentos remanescentes do sudeste brasileiro. A mata bem conservada que recobre os 3300 ha da Serra do Mendanha, apesar de localizada na região metropolitana do Estado do Rio de Janeiro, ainda não tinha sua anurofauna conhecida. No presente estudo, recolhemos informações ecológicas sobre as espécies que habitam a região, especialmente da assembléia encontrada no folhiço que recobre o solo, com o uso de diferentes metodologias: armadilhas de queda; parcelas cercadas; procura visual e auditiva em transecções e encontros ocasionais; assim como dados abióticos do ambiente regional (profundidade do folhiço; níveis de pH; taxa de oxigênio dissolvido; temperaturas do ar e da água; umidade do ar). Exemplares-testemunho foram fixados e depositados na coleção de anfíbios do Museu Nacional, Rio de Janeiro. A anurofauna da Serra do Mendanha é composta por pelo menos 44 espécies que estão distribuídas em 12 famílias, sendo a família Hylidae com o maior número de espécies (50%, n = 22), enquanto que Physalaemus signifer foi a espécie mais abundante (18%, n = 272), sendo habitante do folhiço. A espécie Rhinella ornata contribuiu com a maior biomassa (m = 548 g). Identificamos uma nova espécie de anuro (Brachycephalidae), que também habita o folhiço das cotas altimétricas acima de 700 m. Biogeograficamente a comunidade de anuros da área estudada indicou ser mais similar (68%) com a comunidade da região da Serra da Tiririca e arredores. Comparando-se os três tipo de fisionomias, ou mesohábitats, existentes na Serra do Mendanha, em termos de riqueza e diversidade, a floresta secundária indicou ter os mais elevados índices, seguido pela floresta pouco perturbada e pela monocultura de bananeiras. A assembléia de anuros que habita o folhiço da Serra do Mendanha é composta por nove espécies, que pouco diferiu ao longo de um gradiente altitudinal (0 a 900 m), com o registro das espécies Euparkerella brasiliensis, H. binotatus, Leptodactylus marmoratus e Zachaenus parvulus na maioria das cotas altimétricas. A altitude, a declividade e profundidade do folhiço foram as variáveis abióticas que mais influenciaram na distribuição de abundância e de riqueza de espécies do folhiço. Na estação úmida (setembro a março) a densidade de anuros no folhiço foi de 10,4 ind./100m2, enquanto que na estação seca (abril a agosto) houve uma redução de 34,6% (6,8 ind./100m2). As assembléias de anuros utilizam os recursos hídricos disponíveis na Serra do Mendanha (água da chuva, córregos, fitotelmas, rios e umidade do ar), de diferentes formas, associadas diretamente ao modo reprodutivo de cada espécie. A altitude, a temperatura da água e o pH afetaram a distribuição de espécies de girinos nos diferentes sítios reprodutivos. O modo reprodutivo 1 foi o mais freqüente (n = 18) entre os 14 modos identificados. O estudo de 12 poças (lênticas e lóticas) indicou que estas diferiram consistentemente entre si, seja nas suas dimensões, na composição de suas assembléias de girinos e nos seus componentes abióticos. Diversos predadores de girinos foram encontrados em algumas poças. A assembléia de girinos de cada poça indicou ser moldada pela interação de diferentes fatores ambientais, ecológicos e filogenéticos de cada espécie

The Coleopteran fauna of exposed riverine sediments on the River Dane, Cheshire: A survey report

This is the Coleopteran Fauna of ERS on the river Dane, Cheshire: a survey report produced by the Environment Agency in 2003. A comprehensive survey of the Exposed Riverine Sediment (ERS) on the River Dane, Cheshire was undertaken between mid-April and mid-June 2003. 6 locations were selected and subsequently examined to determine the importance of the constituent invertebrate fauna. Appropriate sampling techniques (i.e. pitfall trapping, hand searching and excavations) were directed towards the target group (Coleoptera). All adults from the chosen taxa were identified to species level. The relative value of the fauna was assessed using species richness, conservation status, fidelity score and a site quality index.

Slow peaking and low-gain designs for global stabilization of nonlinear systems

This paper presents an analysis of the slow-peaking phenomenon, a pitfall of low-gain designs that imposes basic limitations to large regions of attraction in nonlinear control systems. The phenomenon is best understood on a chain of integrators perturbed by a vector field up(x, u) that satisfies p(x, 0) = 0. Because small controls (or low-gain designs) are sufficient to stabilize the unperturbed chain of integrators, it may seem that smaller controls, which attenuate the perturbation up(x, u) in a large compact set, can be employed to achieve larger regions of attraction. This intuition is false, however, and peaking may cause a loss of global controllability unless severe growth restrictions are imposed on p(x, u). These growth restrictions are expressed as a higher order condition with respect to a particular weighted dilation related to the peaking exponents of the nominal system. When this higher order condition is satisfied, an explicit control law is derived that achieves global asymptotic stability of x = 0. This stabilization result is extended to more general cascade nonlinear systems in which the perturbation p(x, v) v, v = (ξ, u) T, contains the state ξ and the control u of a stabilizable subsystem ξ = a(ξ, u). As an illustration, a control law is derived that achieves global stabilization of the frictionless ball-and-beam model.

Spatial distribution of upland beetles in relation to landform, vegetation and grazing management

Dennis, P., Aspinall, R. J., Gordon, I. J. (2002). Spatial distribution of upland beetles in relation to landform vegetation and grazing management. Basic and Applied Ecology, 3 (2), 183?193. Sponsorship: SEERAD RAE2008

Variability in north temperate dung beetle assemblages at different spatial and temporal scales

This study examined the spatial and temporal variability of dung beetle assemblages across a variety of scales e.g. from the between-pad scale (examining the effects of dung size and type) to larger spatial scales encompassing southern Ireland. Dung beetle assemblage structure as sampled by dung pad cohort samples and dung baited pitfall trapping were compared. Generally, the rank order of abundance of dung beetle species was significantly correlated between pitfall catches and cohort pad samples. Across different dung sizes, in both pitfall catches and cohort pad samples, the relative abundance of species was frequently significantly different, but the rank order of abundance of dung beetle was usually significantly correlated. Considerable variations in pitfall catches at temporal scales of a few days appeared to be closely related to weather conditions and rotational grazing. However, despite considerable variation in absolute abundances between consecutive days of sampling, assemblage structure typically remained very similar. The relationship between dung pad size and dung beetle colonisation was investigated. In field experiments in which pads of different sizes (0.25 L, 0.5 L, 1.0 L and 1.5 L) were artificially deposited, there was a positive relationship between pad size and both biomass and number of beetles colonising dung pads and pitfall traps. In addition, with one exception, the field experiments indicated a general positive relationship between dung pad size and biomass density (dung beetle biomass per unit dung volume). A laboratory experiment indicated that pat residence times of A. rufipes were significantly correlated with dung pad size. Investigation of naturally-deposited cow dung pads in the field also indicated that both larval numbers and densities were significantly correlated with dung pad size. These results were discussed in the context of theory related to aggregation and coexistence of species, and resource utilisation by organisms in ephemeral, patchy resources. The colonisation by dung beetles of dung types from native herbivores (sheep, horse and cow) was investigated in field experiments. There were significant differences between the dung types in the chemical parameters measured, and there were significant differences in abundances of dung beetles colonising the dung types. Sheep dung was typically the preferred dung type. Data from these field experiments, and from published literature, indicated that dung beetle species can display dung type preferences, in terms of comparisons of both absolute and relative abundances. In addition, data from laboratory experiments indicate that both Aphodius larval production and pat residence times tended to be higher in those dung types which were preferred by adult Aphodius in the colonisation experiments. Data from dung-baited pitfall trapping (from this and another study) at several sites (up to 180 km distant) and over a number of years (between 1991 and 1996) were used to investigate spatial and temporal variation in dung beetle assemblage structure and composition (Aphodius, Sphaeridium and Geotrupes) across a range of scales in southern Ireland. Species richness levels, species composition and rank order of abundances were very similar between the assemblages. The temporal variability between seasons within any year exceeded temporal variability between years. DCA ordinations indicated that there was a similar level of variability between assemblage structure from the between-field (~1km) to regional (~180 km) spatial scales, and between year (6 years) temporal scales. At the biogeographical spatial scale, analysis of data from the literature indicated that there was considerable variability at this scale, largely due to species turnover.

Invertebrate diversity in Irish and British forests

Ireland and Britain were once covered in natural forest, but extensive anthropogenic deforestation reduced forest cover to less than 1% and 5 %, respectively, by the beginning of the 20th century. Large-scale afforestation has since increased the level of forest cover to 11% in Ireland and 12% in Britain, with the majority of planted forests comprising small monoculture plantations, many of which are of non - native conifer tree species. At present the forest cover of Ireland and Britain generally consists of small areas of remnant semi-natural woodland and pockets of these plantation forests within a predominantly agricultural landscape. Invertebrates comprise a large proportion of the biodiversity found within forested habitats. In particular, spiders and carabid beetles play an important role in food webs as both predators and prey and respond to small-scale changes in habitat structure, meaning they are particularly sensitive to forest management. Hoverflies play an important role in control and pollination and have been successfully used as indicators of habitat disturbance and quality. This research addressed a number of topics pertinent to the forest types present in the contemporary Irish and British landscapes and aimed to investigate the invertebrate diversity of these forests. Spiders and carabid beetles were sampled using pitfall trapping and hoverflies were sampled using Malaise net trapping. Topics included the impacts of afforestation, the importance of open space, the choice of tree species, and the use of indicators for biodiversity assessment, as well as rare native woodlands and the effect of grazing on invertebrate diversity. The results are discussed and evidence-based recommendations are made for forest policy and management to protect and enhance invertebrate biodiversity in order to promote sustainable forest management in Ireland and Britain.

THE IMPACT OF GRAZING ON COMMUNITIES OF GROUND-DWELLING SPIDERS (ARANEAE) IN UPLAND VEGETATION TYPES

Adult spider communities were sampled by pitfall trapping over a 24-month period in plots subjected to a range of grazing regimes on five vegetation types on a hill farm in County Antrim, north-east Ireland. Spider community composition was influenced by vegetation type and grazing regime. Variation in the number of individuals and species diversity was also apparent between vegetation types and grazing regime. Plots grazed by all herbivores were characterised by the predominance of species characteristic of disturbed land. Inbye land and areas where grazing had ceased had characteristic coloniser species. The spiders Erigone dentipalpis, Allomengea scopigera and Centromerita bicolor were trapped with greater success in vegetation types where grass species dominated.

Entomofauna associated with the olive tree in southern Portugal

Since 2004 several studies have been carried out in order to identify the main insect species that usually inhabiting the olive ecosystem. The field trials have taken place in two olive groves, one situated in Olhão and the other one in Loulé, both in Algarve and also under Integrated Pest Management (IPM). The sampling techniques used differ according to their purpose (sticky traps, pheromone traps, pitfall traps and samples of aerial parts of the trees such as inflorescences, leaves, fruits and branches). Results showed that the main insect pests of olive tree in southern Portugal were the olive fruit fly Bactrocera oleae Gmelin (Diptera: Tephritidae) and the olive moth Prays oleae Bernard (Lepidoptera: Hyponeumetidae). Other insect pests were also found in our olive groves namely the olive psyllid Euphyllura olivina Costa (Homoptera: Psyllidae), the olive dark beetle Phloeotribus scarabaeoides Bernard (Coleoptera: Curculionidae), the mediterranean black scale Saissetia oleae (Olivier) (Homoptera: Coccidae) and the olive thrip Liothripes oleae Costa (Thysanoptera: Phlaeothripidae). Concerning the auxiliary insects that were found in our olives groves they belong to the following orders and families: Diptera (Syrphidae), Coleoptera (Carabidae, Coccinelidae and Staphylinidae), Hemiptera (Anthocoridae and Miridae), Neuroptera (Chrysopidae) and Hymenoptera (Braconidae, Encyrtidae, Eulophidae, Formicidae and Trichogrammatidae).

Evaluation of an antireflux procedure for colonic interposition in pediatric esophageal replacements.

Background: In 1989, we introduced a 1-stage procedure with orthotopic colonic transplants for esophageal stenosis. A pitfall of this procedure is frequent reflux and/or stasis in the transplants from the cologastric anastomosis. Since 1993, we have used a new antireflux wrap (ARW) using an anterior wrap technique similar to the Dor procedure but fixed to the right crus of the diaphragm.Purpose: The purpose of the study was to evaluate ARWs.Method: From 1993 to 2008, the records of 67 patients with an ARW were compared with 27 without ARW (either operated on before 1993 or ARW was not appropriate) after colonic transplant for caustic esophageal stenosis. Both groups otherwise underwent the same surgical procedure. Postoperative esophagograms done on postoperative day 10 were reviewed for the presence of gastrocolonic reflux and stasis in the transplant.Results: The reflux rate on the initial esophagogram was reduced from 48.1% to 7.5% using ARW. The incidence of reflux on later esophagograms was 40.0% with no ARW and 21.4% with ARW. The 25% long-term rate of stasis in the colonic transplant was not increased with ARW.Conclusions: A loose ARW in patients with colonic esophageal replacements reduces gastrocolic reflux without increasing the rate of stasis. In the long term, children adapt better to stasis than to reflux and are thus protected from occult inflammation.

Mass spectrometry as a tool to dissect the role of chromatin assembly factors in regulating nucleosome assembly

L'assemblage des nucléosomes est étroitement couplée à la synthèse des histones ainsi qu’à la réplication et la réparation de l’ADN durant la phase S. Ce processus implique un mécanisme de contrôle qui contribue soigneusement et de manière régulée à l’assemblage de l’ADN en chromatine. L'assemblage des nucléosomes durant la synthèse de l’ADN est crucial et contribue ainsi au maintien de la stabilité génomique. Cette thèse décrit la caractérisation par spectrométrie de masse(SM) des protéines jouant un rôle critique dans l’assemblage et le maintien de la structure chromatinienne. Plus précisément, la phosphorylation de deux facteurs d’assemblage des nucléosome, le facteur CAF-1, une chaperone d’histone qui participe à l'assemblage de la chromatine spécifiquement couplée à la réplication de l'ADN, ainsi que le complexe protéique Hir, jouant de plus un rôle important dans la régulation transcriptionelle des gènes d’histones lors de la progression normale du cycle cellulaire et en réponse aux dommages de l'ADN, a été examiné. La caractérisation des sites de phosphorylation par SM nécéssite la séparation des protéines par éléctrophorèse suivi d’une coloration a l’argent. Dans le chapitre 2, nous demontrons que la coloration à l’argent induit un artéfact de sulfatation. Plus précisément, cet artéfact est causé par un réactif spécifiquement utilisé lors de la coloration. La sulfatation présente de fortes similitudes avec la phosphorylation. Ainsi, l’incrément de masse observé sur les peptides sulfatés et phosphorylés (+80 Da) nécéssite des instruments offrant une haute résolution et haute précision de masse pour différencier ces deux modifications. Dans les chapitres 3 et 4, nous avons d’abord démontré par SM que Cac1, la plus grande sous-unité du facteur CAF-1, est cible de plusieurs sites de phosphorylation. Fait intéréssant, certains de ces sites contiennent des séquences consensus pour les kinases Cdc7-Dbf4 et CDKs. Ainsi, ces résultats fournissent les premières évidences que CAF-1 est potentiellement régulé par ces deux kinases in vivo. La fonction de tous les sites de phosphorylation identifiés a ensuite été évaluée. Nous avons démontré que la phosphorylation de la Ser-503, un site consensus de la DDK, est essentielle à la répréssion transcriptionelle des gènes au niveau des télomères. Cependant, cette phosphorylation ne semble pas être nécéssaire pour d’autres fonctions connues de CAF-1, indiquant que le blocage de la phsophorylation de Cac1 Ser-503 affecte spécifiquement la fonction de CAF-1 aux structures hétérochromatiques des télomères. Ensuite, nous avons identifiés une intéraction physique entre CAF-1 et Cdc7-Dbf4. Des études in vitro ont également demontré que cette kinase phosphoryle spécifiquement Cac1 Ser-503, suggérant un rôle potential pour la kinase Cdc7-Dbf4 dans l’assemblage et la stabilité de la structure hétérochromatique aux télomères. Finalement, les analyses par SM nous ont également permi de montrer que la sous-unité Hpc2 du complexe Hir est phosphorylée sur plusieurs sites consensus des CDKs et de Cdc7-Dbf4. De plus, la quantification par SM d’un site spécifique de phosphorylation de Hpc2, la Ser-330, s’est révélée être fortement induite suite à l’activation du point de contrôle de réplication (le “checkpoint”) suite au dommage a l’ADN. Nous montrons que la Ser-330 de Hpc2 est phopshorylée par les kinases de point de contrôle de manière Mec1/Tel1- et Rad53-dépendante. Nos données préliminaires suggèrent ainsi que la capacité du complex Hir de réguler la répréssion transcriptionelle des gènes d'histones lors de la progression du cycle cellulaire normal et en réponse au dommage de l'ADN est médiée par la phosphorylation de Hpc2 par ces deux kinases. Enfin, ces deux études mettent en évidence l'importance de la spectrométrie de masse dans la caractérisation des sites de phosphorylation des protéines, nous permettant ainsi de comprendre plus précisement les mécanismes de régulation de l'assemblage de la chromatine et de la synthèse des histones.

Perfil de mercado de la Unión Europea y los países de la EFTA

El presente trabajo de grado busca evaluar el perfil del mercado de la Unión Europea y los países de la EFTA para identificar las oportunidades comerciales de Colombia, más específicamente en los siguientes países: Suiza, Noruega, Liechtenstein, Islandia, Republica Checa, Rumania y Suecia. A través de esta investigación se realizó un análisis de los 25 productos más exportados de Colombia a cada uno de los países estudiados, tomando en cuenta sus códigos arancelarios. Adicionalmente, se evaluaron las balanzas comerciales de cada uno de los países, las tendencias de las exportaciones Colombianas de los últimos años, y las posibles oportunidades de mercados teniendo en cuenta las necesidades de importaciones detalladas de cada país europeo. A partir de la información encontrada la investigación se concentró en la proveniencia exacta del departamento Colombiano que hacia las exportaciones de los 25 productos más representativos a cada uno de los países evaluados. Teniendo en cuenta esta información, se evaluó por departamento, las oportunidades y perfiles de mercado de exportación hacia Suiza, Noruega, Liechtenstein, Islandia, Republica Checa, Rumania y Suecia. Finalmente se identificaron los 10 productos más exportados de Colombia a cada uno de los países analizados, con el fin de enfocar las mejoras y potencializar las exportaciones de estos productos a los países europeos evaluados. Adicionalmente durante la investigación se realizan recomendaciones específicas por país y al final del documento se encuentran las conclusiones generales y recomendaciones principales para futuras exportaciones de Colombia a los países de la EFTA, República Checa, Rumania y Suecia.

Modelos de presupuestación de capital en finanzas corporativas y utilidad de los mismos

La siguiente investigación describe una aproximación teórica al tema de los modelos de presupuestación de capital, el objetivo fundamental se basa en comprender su enfoque e importancia al momento de tomar decisiones de inversión por parte de los directores de una empresa, así como de prever los efectos de esta en un futuro. Al respecto, y sobre la base de que los modelos de presupuestación de capital son herramientas para analizar posibles erogaciones de capital por parte de una empresa, es necesario para efectos del presente proyecto de investigación, definir sus diferentes modelos desde lo teórico y metodológico, explicando los diferentes conceptos relacionados con el tema. Así mismo, se explican algunos de los indicadores financieros utilizados en las compañías para medir y estimar la “salud financiera” de la empresa, además de puntualizar su impacto en la perdurabilidad de las entidades, lo cual permite dar una visión más general sobre la importancia que trasciende de los indicadores financieros, generando un impacto positivo en la evolución o crecimiento de la organización. En complemento, la investigación aborda la presupuestación de capital de manera particular aplicado en la gestión empresarial, sean estas privadas o públicas (estatal y gubernamental). En este sentido, se abordan conceptos elaborados por diferentes académicos en los que se exponen algunas aproximaciones respecto al posible mejoramiento de la presupuestación para los sectores a los que pertenecen determinadas entidades. Finalmente, se presenta de manera explícita las conclusiones que surgieron a lo largo de la construcción del documento de investigación, con el fin de dar cumplimiento concreto al objetivo general del trabajo, el cual constituye una respuesta a la pregunta de investigación que se enunciará en el desarrollo del documento.

Experimental verification of suction sampler capture efficiency in grasslands of differing vegetation height and structure

1. Suction sampling is a popular method for the collection of quantitative data on grassland invertebrate populations, although there have been no detailed studies into the effectiveness of the method. 2. We investigate the effect of effort (duration and number of suction samples) and sward height on the efficiency of suction sampling of grassland beetle, true bug, planthopper and spider Populations. We also compare Suction sampling with an absolute sampling method based on the destructive removal of turfs. 3. Sampling for durations of 16 seconds was sufficient to collect 90% of all individuals and species of grassland beetles, with less time required for the true bugs, spiders and planthoppers. The number of samples required to collect 90% of the species was more variable, although in general 55 sub-samples was sufficient for all groups, except the true bugs. Increasing sward height had a negative effect on the capture efficiency of suction sampling. 4. The assemblage structure of beetles, planthoppers and spiders was independent of the sampling method (suction or absolute) used. 5. Synthesis and applications. In contrast to other sampling methods used in grassland habitats (e.g. sweep netting or pitfall trapping), suction sampling is an effective quantitative tool for the measurement of invertebrate diversity and assemblage structure providing sward height is included as a covariate. The effective sampling of beetles, true bugs, planthoppers and spiders altogether requires a minimum sampling effort of 110 sub-samples of duration of 16 seconds. Such sampling intensities can be adjusted depending on the taxa sampled, and we provide information to minimize sampling problems associated with this versatile technique. Suction sampling should remain an important component in the toolbox of experimental techniques used during both experimental and management sampling regimes within agroecosystems, grasslands or other low-lying vegetation types.

The effects of the insecticide chlorpyrifos on spider and Collembola communities

The effects of chlorpyrifos on aquatic systems are well documented. However, the consequences of the pesticide on soil food webs are poorly understood. In this field study, we hypothesised that the addition of a soil insecticide to an area of upland grassland would impact spider and Collembola communities by decreasing numbers of spiders, consequently, causing an increase in detritivore numbers and diversity. Chlorpyrifos was added to plots on an upland grassland in a randomised block design. Populations of Collembola and spiders were sampled by means of pitfall traps (activity density) and identified to species. Twelve species of Collembola were identified from the insecticide-treated and control plots. Species diversity, richness and evenness were all reduced in the chlorpyrifos plots, although the total number of Collembola increased ten-fold despite the abundance of some spider species being reduced. The dominant collembolan in the insecticide-treated plots was Ceratophysella denticulata, accounting for over 95% of the population. Forty-three species of spider were identified. There were a reduced number of spiders in insecticide-treated plots due mainly to a lower number of the linyphiid, Tiso vagans. However, there was no significant difference in spider diversity between the control and insecticide treatments. We discuss possible explanations for the increase in abundance of one collembolan species in response to chlorpyrifos and the consequences of this. The study emphasises the importance of understanding the effects of soil management practices on soil biodiversity, which is under increasing pressure from land development and food production. It also highlights the need for identification of soil invertebrates to an 'appropriate' taxonomic level for biodiversity estimates. (C) 2007 Elsevier GrnbH. All rights reserved.