Showing papers by "Colorado State University published in 2009"
TL;DR: In this paper, the authors use a spatially explicit modeling tool, integrated valuation of ecosystem services and tradeoffs (InVEST), to predict changes in ecosystem services, biodiversity conservation, and commodity production levels.
Abstract: Nature provides a wide range of benefits to people. There is increasing consensus about the importance of incorporating these “ecosystem services” into resource management decisions, but quantifying the levels and values of these services has proven difficult. We use a spatially explicit modeling tool, Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST), to predict changes in ecosystem services, biodiversity conservation, and commodity production levels. We apply InVEST to stakeholder-defined scenarios of land-use/land-cover change in the Willamette Basin, Oregon. We found that scenarios that received high scores for a variety of ecosystem services also had high scores for biodiversity, suggesting there is little tradeoff between biodiversity conservation and ecosystem services. Scenarios involving more development had higher commodity production values, but lower levels of biodiversity conservation and ecosystem services. However, including payments for carbon sequestration alleviates this tradeoff. Quantifying ecosystem services in a spatially explicit manner, and analyzing tradeoffs between them, can help to make natural resource decisions more effective, efficient, and defensible.
2,056 citations
TL;DR: Range edges are characterized by increased genetic isolation, genetic differentiation, and variability in individual and population performance, but evidence for decreased abundance and fitness is lacking, and a better fusion of experimentation and theory will advance understanding of the causes of range limits.
Abstract: Species range limits involve many aspects of evolution and ecology, from species distribution and abundance to the evolution of niches. Theory suggests myriad processes by which range limits arise, including competitive exclusion, Allee effects, and gene swamping; however, most models remain empirically untested. Range limits are correlated with a number of abiotic and biotic factors, but further experimentation is needed to understand underlying mechanisms. Range edges are characterized by increased genetic isolation, genetic differentiation, and variability in individual and population performance, but evidence for decreased abundance and fitness is lacking. Evolution of range limits is understudied in natural systems; in particular, the role of gene flow in shaping range limits is unknown. Biological invasions and rapid distribution shifts caused by climate change represent large-scale experiments on the underlying dynamics of range limits. A better fusion of experimentation and theory will advance our understanding of the causes of range limits.
1,534 citations
TL;DR: A multidisciplinary, multilevel, and global perspective is adopted to demonstrate that training and development activities in work organizations can produce important benefits for each of these stakeholders.
Abstract: This article provides a review of the training and development literature since the year 2000. We review the literature focusing on the benefits of training and development for individuals and teams, organizations, and society. We adopt a multidisciplinary, multilevel, and global perspective to demonstrate that training and development activities in work organizations can produce important benefits for each of these stakeholders. We also review the literature on needs assessment and pretraining states, training design and delivery, training evaluation, and transfer of training to identify the conditions under which the benefits of training and development are maximized. Finally, we identify research gaps and offer directions for future research.
1,213 citations
TL;DR: The costs and benefits of IAS for provisioning, regulating and cultural services are assessed, and the synergies and tradeoffs associated with these impacts are illustrated using case studies that include South Africa, the Great Lakes and Hawaii.
Abstract: Although the effects of invasive alien species (IAS) on native species are well documented, the many ways in which such species impact ecosystem services are still emerging. Here we assess the costs and benefits of IAS for provisioning, regulating and cultural services, and illustrate the synergies and tradeoffs associated with these impacts using case studies that include South Africa, the Great Lakes and Hawaii. We identify services and interactions that are the least understood and propose a research and policy framework for filling the remaining knowledge gaps. Drawing on ecology and economics to incorporate the impacts of IAS on ecosystem services into decision making is key to restoring and sustaining those life-support services that nature provides and all organisms depend upon.
1,125 citations
TL;DR: This study shows the successful integration of paper-based microfluidics and electrochemical detection as an easy-to-use, inexpensive, and portable alternative for point of care monitoring.
Abstract: We report the first demonstration of electrochemical detection for paper-based microfluidic devices. Photolithography was used to make microfluidic channels on filter paper, and screen-printing technology was used to fabricate electrodes on the paper-based microfluidic devices. Screen-printed electrodes on paper were characterized using cyclic voltammetry to demonstrate the basic electrochemical performance of the system. The utility of our devices was then demonstrated with the determination of glucose, lactate, and uric acid in biological samples using oxidase enzyme (glucose oxidase, lactate oxidase, and uricase, respectively) reactions. Oxidase enzyme reactions produce H2O2 while decomposing their respective substrates, and therefore a single electrode type is needed for detection of multiple species. Selectivity of the working electrode for H2O2 was improved using Prussian Blue as a redox mediator. The determination of glucose, lactate, and uric acid in control serum samples was performed using chron...
1,037 citations
Utah State University1, Virginia Tech2, University of Arizona3, University of Maryland, College Park4, University of New Hampshire5, University of Wisconsin-Madison6, Harvard University7, Ames Research Center8, United States Geological Survey9, University of Montana10, University of Wisconsin–Milwaukee11, University of California, Berkeley12, University of Maine13, Colorado State University14
TL;DR: In this paper, the authors assess 10 start-of-spring (SOS) methods for North America between 1982 and 2006 and find that SOS estimates were more related to the first leaf and first flowers expanding phenological stages.
Abstract: Shifts in the timing of spring phenology are a central feature of global change research. Long-term observations of plant phenology have been used to track vegetation responses to climate variability but are often limited to particular species and locations and may not represent synoptic patterns. Satellite remote sensing is instead used for continental to global monitoring. Although numerous methods exist to extract phenological timing, in particular start-of-spring (SOS), from time series of reflectance data, a comprehensive intercomparison and interpretation of SOS methods has not been conducted. Here, we assess 10 SOS methods for North America between 1982 and 2006. The techniques include consistent inputs from the 8 km Global Inventory Modeling and Mapping Studies Advanced Very High Resolution Radiometer NDVIg dataset, independent data for snow cover, soil thaw, lake ice dynamics, spring streamflow timing, over 16 000 individual measurements of ground-based phenology, and two temperature-driven models of spring phenology. Compared with an ensemble of the 10 SOS methods, we found that individual methods differed in average day-of-year estimates by � 60 days and in standard deviation by � 20 days. The ability of the satellite methods to retrieve SOS estimates was highest in northern latitudes and lowest in arid, tropical, and Mediterranean ecoregions. The ordinal rank of SOS methods varied geographically, as did the relationships between SOS estimates and the cryospheric/hydrologic metrics. Compared with ground observations, SOS estimates were more related to the first leaf and first flowers expanding phenological stages. We found no evidence for time trends in spring arrival from ground- or model-based data; using an ensemble estimate from two methods that were more closely related to ground observations than other methods, SOS
831 citations
TL;DR: In this article, the authors established the constructs of calling and vocation within counseling psychology, with an eye toward stimulating research and providing useful practice applications, and explained how the constructs apply to the domain of human work, review empirical and theoretical work related to calling, and differentiate the terms from each other and related constructs.
Abstract: The purpose of this article is to initiate an effort to establish the constructs calling and vocation within counseling psychology First, updated definitions of calling and vocation, developed with an eye toward stimulating research and providing useful practice applications, are proposed Next, the authors explain how the constructs apply to the domain of human work, review empirical and theoretical work related to calling and vocation and their role in human functioning, and differentiate the terms from each other and related constructs Finally, directions for basic and applied research on calling and vocation are suggested, and implications for career counseling practice are outlined
754 citations
TL;DR: It is shown that atmospheric N deposition increased the stoichiometric ratio of N and phosphorus in lakes in Norway, Sweden, and Colorado, United States, and, as a result, patterns of ecological nutrient limitation were shifted.
Abstract: Human activities have more than doubled the amount of nitrogen (N) circulating in the biosphere. One major pathway of this anthropogenic N input into ecosystems has been increased regional deposition from the atmosphere. Here we show that atmospheric N deposition increased the stoichiometric ratio of N and phosphorus (P) in lakes in Norway, Sweden, and Colorado, United States, and, as a result, patterns of ecological nutrient limitation were shifted. Under low N deposition, phytoplankton growth is generally N-limited; however, in high-N deposition lakes, phytoplankton growth is consistently P-limited. Continued anthropogenic amplification of the global N cycle will further alter ecological processes, such as biogeochemical cycling, trophic dynamics, and biological diversity, in the world's lakes, even in lakes far from direct human disturbance.
692 citations
TL;DR: In this article, a review of recent advances in the processing of microwave ferrites is presented, including self-bias magnetization, tunability of the magnetic anisotropy, low microwave loss, and volumetric and weight reduction.
686 citations
TL;DR: The physiological and anatomical characteristics of native bone are reviewed, key technologies in mimicking the physical and chemical environment of bone using synthetic materials are described, and an overview of local drug delivery as it pertains to bone tissue engineering is included.
Abstract: Critical-sized defects in bone, whether induced by primary tumor resection, trauma, or selective surgery have in many cases presented insurmountable challenges to the current gold standard treatment for bone repair. The primary purpose of a tissue-engineered scaffold is to use engineering principles to incite and promote the natural healing process of bone which does not occur in critical-sized defects. A synthetic bone scaffold must be biocompatible, biodegradable to allow native tissue integration, and mimic the multidimensional hierarchical structure of native bone. In addition to being physically and chemically biomimetic, an ideal scaffold is capable of eluting bioactive molecules (e.g., BMPs, TGF-betas, etc., to accelerate extracellular matrix production and tissue integration) or drugs (e.g., antibiotics, cisplatin, etc., to prevent undesired biological response such as sepsis or cancer recurrence) in a temporally and spatially controlled manner. Various biomaterials including ceramics, metals, polymers, and composites have been investigated for their potential as bone scaffold materials. However, due to their tunable physiochemical properties, biocompatibility, and controllable biodegradability, polymers have emerged as the principal material in bone tissue engineering. This article briefly reviews the physiological and anatomical characteristics of native bone, describes key technologies in mimicking the physical and chemical environment of bone using synthetic materials, and provides an overview of local drug delivery as it pertains to bone tissue engineering is included.
669 citations
TL;DR: The authors assessed the structure, levels, and correlates of the presence of meaning in life, and the search for meaning, within four life stage groups: emerging adulthood, young adulthood, middle-age adulthood, and older adulthood.
Abstract: Meaning in life is thought to be important to well-being throughout the human life span. We assessed the structure, levels, and correlates of the presence of meaning in life, and the search for meaning, within four life stage groups: emerging adulthood, young adulthood, middle-age adulthood, and older adulthood. Results from a sample of Internet users (N = 8756) demonstrated the structural invariance of the meaning measure used across life stages. Those at later life stages generally reported a greater presence of meaning in their lives, whereas those at earlier life stages reported higher levels of searching for meaning. Correlations revealed that the presence of meaning has similar relations to well-being across life stages, whereas searching for meaning is more strongly associated with well-being deficits at later life stages.
TL;DR: Three problem areas in the protein aggregation kinetic and mechanistic studies area are identified, and a Summary and Conclusions section is provided en route to moving the field forward towards the still unachieved goal of unequivocal elucidation of the mechanism(s) of protein aggregation.
TL;DR: Introgression patterns of shared SNPs revealed the breeding history and relationships among the 20 varieties; some introgressed regions are associated with agronomic traits that mark major milestones in rice improvement.
Abstract: Rice, the primary source of dietary calories for half of humanity, is the first crop plant for which a high-quality reference genome sequence from a single variety was produced. We used resequencing microarrays to interrogate 100 Mb of the unique fraction of the reference genome for 20 diverse varieties and landraces that capture the impressive genotypic and phenotypic diversity of domesticated rice. Here, we report the distribution of 160,000 nonredundant SNPs. Introgression patterns of shared SNPs revealed the breeding history and relationships among the 20 varieties; some introgressed regions are associated with agronomic traits that mark major milestones in rice improvement. These comprehensive SNP data provide a foundation for deep exploration of rice diversity and gene–trait relationships and their use for future rice improvement.
TL;DR: In-depth characterization indicated that pure stoichiometric CZTS nanocrystals with an average particle size of 12.8 +/- 1.8 nm were formed, and optical measurements showed a band gap of 1.5 eV, which is optimal for a single-junction solar device.
Abstract: Recent advances have been made in thin-film solar cells using CdTe and CuIn1−xGaxSe2 (CIGS) nanoparticles, which have achieved impressive efficiencies. Despite these efficiencies, CdTe and CIGS are not amenable to large-scale production because of the cost and scarcity of Te, In, and Ga. Cu2ZnSnS4 (CZTS), however, is an emerging solar cell material that contains only earth-abundant elements and has a near-optimal direct band gap of 1.45−1.65 eV and a large absorption coefficient. Here we report the direct synthesis of CZTS nanocrystals using the hot-injection method. In-depth characterization indicated that pure stoichiometric CZTS nanocrystals with an average particle size of 12.8 ± 1.8 nm were formed. Optical measurements showed a band gap of 1.5 eV, which is optimal for a single-junction solar device.
TL;DR: The beneficial effects of low doses of Al, Co, Na, sodium, selenium, Se and Se have received little attention compared to toxic effects that typically occur at higher concentrations.
TL;DR: The use of analytical mathematical tools, particularly modeling, in the development of control policies and research agendas is reviewed and significant gaps are highlighted in analytical efforts during spillover transmission from animals into humans.
Abstract: Few infectious diseases are entirely human-specific: Most human pathogens also circulate in animals or else originated in nonhuman hosts. Influenza, plague, and trypanosomiasis are classic examples of zoonotic infections that transmit from animals to humans. The multihost ecology of zoonoses leads to complex dynamics, and analytical tools, such as mathematical modeling, are vital to the development of effective control policies and research agendas. Much attention has focused on modeling pathogens with simpler life cycles and immediate global urgency, such as influenza and severe acute respiratory syndrome. Meanwhile, vector-transmitted, chronic, and protozoan infections have been neglected, as have crucial processes such as cross-species transmission. Progress in understanding and combating zoonoses requires a new generation of models that addresses a broader set of pathogen life histories and integrates across host species and scientific disciplines.
TL;DR: In this article, the authors examine the emergence and implications of transnational climate change governance and develop a typology based on the actors involved and their authority, and the primary governance functions performed in order to steer network constituents.
Abstract: In this article we examine the emergence and implications of transnational climate-change governance. We argue that although the study of transnational relations has recently been renewed alongside a burgeoning interest in issues of global governance, the nature of transnational governance has to date received less attention. We contend that transnational governance occurs when networks operating in the transnational political sphere authoritatively steer constituents toward public goals. In order to stimulate a more systematic study of the diversity and significance of this phenomenon, the article develops a typology based on the actors involved and their authority—public, private, or hybrid—and the primary governance functions performed in order to steer network constituents—information-sharing, capacity building and implementation, or rule-setting. A comparative discussion of transnational governance networks for climate change illustrates each category and the value of the typology in assessing the mu...
TL;DR: It is shown that the proposed methods also possess the sure screening property with vanishing false selection rate, which justifies the applicability of such a simple method in a wide spectrum.
Abstract: Ultrahigh-dimensional variable selection plays an increasingly important role in contemporary scientific discoveries and statistical research. Among others, Fan and Lv [J. R. Stat. Soc. Ser. B Stat. Methodol. 70 (2008) 849-911] propose an independent screening framework by ranking the marginal correlations. They showed that the correlation ranking procedure possesses a sure independence screening property within the context of the linear model with Gaussian covariates and responses. In this paper, we propose a more general version of the independent learning with ranking the maximum marginal likelihood estimates or the maximum marginal likelihood itself in generalized linear models. We show that the proposed methods, with Fan and Lv [J. R. Stat. Soc. Ser. B Stat. Methodol. 70 (2008) 849-911] as a very special case, also possess the sure screening property with vanishing false selection rate. The conditions under which the independence learning possesses a sure screening is surprisingly simple. This justifies the applicability of such a simple method in a wide spectrum. We quantify explicitly the extent to which the dimensionality can be reduced by independence screening, which depends on the interactions of the covariance matrix of covariates and true parameters. Simulation studies are used to illustrate the utility of the proposed approaches. In addition, we establish an exponential inequality for the quasi-maximum likelihood estimator which is useful for high-dimensional statistical learning.
TL;DR: This work reviews the current literature pertaining to the chemical communication that exists between plants and microorganisms and the biological processes they sustain in the rhizosphere.
TL;DR: Key developments in the current understanding of Se in higher plants are reviewed and recent advances in the genetic engineering of Se metabolism are discussed, particularly for biofortification and phytoremediation of Se-contaminated environments.
TL;DR: Phenology is the study of recurring life-cycle events, classic examples being the flowering of plants and animal migration as mentioned in this paper, which are increasingly relevant for addressing applied environmental issues.
Abstract: Phenology is the study of recurring life-cycle events, classic examples being the flowering of plants and animal migration. Phenological responses are increasingly relevant for addressing applied environmental issues. Yet, challenges remain with respect to spanning scales of observation, integrating observations across taxa, and modeling phenological sequences to enable ecological forecasts in light of future climate change. Recent advances that are helping to address these questions include refined landscape-scale phenology estimates from satellite data, advanced, instrument-based approaches for field measurements, and new cyberinfrastructure for archiving and distribution of products. These breakthroughs are improving our understanding in diverse areas, including modeling land-surface exchange, evaluating climate–phenology relationships, and making land-management decisions.
TL;DR: The hierarchical-response framework is explicitly comparative to better understand differential sensitivities of ecosystems, and it can be used to guide the design of coordinated, cross-site experiments to enable more robust forecasts of contemporary and future ecosystem dynamics.
Abstract: In contrast to pulses in resource availability following disturbance events, many of the most pressing global changes, such as elevated atmospheric carbon dioxide concentrations and nitrogen deposition, lead to chronic and often cumulative alterations in available resources. Therefore, predicting ecological responses to these chronic resource alterations will require the modification of existing disturbance-based frameworks. Here, we present a conceptual framework for assessing the nature and pace of ecological change under chronic resource alterations. The "hierarchical-response framework" (HRF) links well-documented, ecological mechanisms of change to provide a theoretical basis for testing hypotheses to explain the dynamics and differential sensitivity of ecosystems to chronic resource alterations. The HRF is based on a temporal hierarchy of mechanisms and responses beginning with individual (physiological/metabolic) responses, followed by species reordering within communities, and finally species loss and immigration. Each mechanism is hypothesized to differ in the magnitude and rate of its effects on ecosystem structure and function, with this variation depending on ecosystem attributes, such as longevity of dominant species, rates of biogeochemical cycling, levels of biodiversity, and trophic complexity. Overall, the HRF predicts nonlinear changes in ecosystem dynamics, with the expectation that interactions with natural disturbances and other global-change drivers will further alter the nature and pace of change. The HRF is explicitly comparative to better understand differential sensitivities of ecosystems, and it can be used to guide the design of coordinated, cross-site experiments to enable more robust forecasts of contemporary and future ecosystem dynamics.
TL;DR: Ca2+ signal to salicylic-acid-mediated immune response through calmodulin, AtSR1 (also known as CAMTA3), a Ca2+/calmodulin-binding transcription factor, and EDS1, an established regulator ofsalicylic acid level are reported.
Abstract: Intracellular calcium transients during plant-pathogen interactions are necessary early events leading to local and systemic acquired resistance. Salicylic acid, a critical messenger, is also required for both of these responses, but whether and how salicylic acid level is regulated by Ca(2+) signalling during plant-pathogen interaction is unclear. Here we report a mechanism connecting Ca(2+) signal to salicylic-acid-mediated immune response through calmodulin, AtSR1 (also known as CAMTA3), a Ca(2+)/calmodulin-binding transcription factor, and EDS1, an established regulator of salicylic acid level. Constitutive disease resistance and elevated levels of salicylic acid in loss-of-function alleles of Arabidopsis AtSR1 suggest that AtSR1 is a negative regulator of plant immunity. This was confirmed by epistasis analysis with mutants of compromised salicylic acid accumulation and disease resistance. We show that AtSR1 interacts with the promoter of EDS1 and represses its expression. Furthermore, Ca(2+)/calmodulin-binding to AtSR1 is required for suppression of plant defence, indicating a direct role for Ca(2+)/calmodulin in regulating the function of AtSR1. These results reveal a previously unknown regulatory mechanism linking Ca(2+) signalling to salicylic acid level.
TL;DR: The aim of this review was to establish ana-C2v-Ligated Catalysts as a stand-alone database of Lanthanide Complexes with a focus on the latter stages of their development in the second half of the 1990s.
Abstract: 1.3. Scope of Review 5161 2. Methacrylate Polymerization 5161 2.1. Lanthanide Complexes 5161 2.1.1. Nonbridged Lanthanocenes 5161 2.1.2. ansa-Lanthanocenes 5164 2.1.3. Half-Lanthanocenes 5166 2.1.4. Non-lanthanocenes 5166 2.2. Group 4 Metallocenes 5170 2.2.1. Nonbridged Catalysts 5170 2.2.2. ansa-C2v-Ligated Catalysts 5173 2.2.3. ansa-C2-Ligated Catalysts 5173 2.2.4. ansa-C1-Ligated Catalysts 5176 2.2.5. ansa-Cs-Ligated Catalysts 5177 2.2.6. Constrained Geometry Catalysts 5178 2.2.7. Half-Metallocene Catalysts 5180 2.2.8. Supported Catalysts 5180 2.3. Other Metallocene Catalysts 5180 2.4. Nonmetallocene Catalysts 5181 2.4.1. Group 1 and 2 Catalysts 5181 2.4.2. Group 13 Catalysts 5183 2.4.3. Group 14 Catalysts 5186 2.4.4. Transition-Metal Catalysts 5187 3. Acrylate Polymerization 5188 3.1. Lanthanocenes 5188 3.2. Group 4 Metallocenes 5189 3.3. Nonmetallocenes 5190 4. Acrylamide and Methacrylamide Polymerization 5191 4.1. Acrylamides 5191 4.2. Methacrylamides 5192 4.3. Asymmetric Polymerization 5193 5. Acrylonitrile and Vinyl Ketone Polymerization 5196 5.1. Acrylonitrile 5196 5.2. Vinyl Ketones 5196 6. Copolymerization 5197 6.1. Polar-Nonpolar Block Copolymers 5197 6.2. Polar-Nonpolar Random Copolymers 5199 6.3. Polar-Polar Copolymers 5204 7. Ion-Pairing Polymerization 5206 8. Summary and Outlook 5208 9. Acknowledgments 5208 10. References 5208
TL;DR: It is demonstrated that the new cortical trajectory and screw design have equivalent pullout and toggle characteristics compared with the traditional trajectory pedicle screw, thus confirming preliminary clinical evidence.
TL;DR: In this paper, the first quantification of home-field advantage in relation to leaf litter decomposition using published litter mass loss data from forest ecosystems in North America, South America, and Europe was provided.
Abstract: Several leaf litter decay studies have indicated that decomposition occurs more rapidly when litter is placed beneath the plant species from which it had been derived than beneath a different plant species (i.e. home-field advantage, HFA), although support for this notion has not been universal. We provide the first quantification of HFA in relation to leaf litter decomposition using published litter mass loss data from forest ecosystems in North America, South America, and Europe. Our findings indicate that HFA is widespread in forest ecosystems; on average litter mass loss was 8% faster at home than away. We hypothesize that HFA results from specialization of the soil biotic community in decomposing litter derived from the plant above it. Climate and initial litter quality data can be used to explain about 70% of the variability in litter decomposition at a global scale, leaving about 30% unexplained. We suggest that HFA be recognized as a factor that explains some of this remaining variability.
TL;DR: In this paper, aircraft-aerosol time-of-flight spectroscopy measurements of ice residues indicate that biological particles trigger ice formation in high-altitude clouds, which is one of the largest remaining sources of uncertainty in climate change projections.
Abstract: The impact of aerosol particles on the formation and properties of clouds is one of the largest remaining sources of uncertainty in climate change projections. Now, aircraft-aerosol time-of-flight spectroscopy measurements of ice residues indicate that biological particles trigger ice formation in high-altitude clouds.
TL;DR: The findings thus far provide good evidence for the psychometric properties of the 10-item CEI-II, including positive correlations with personal growth, openness to experience, autonomy, purpose in life, self- acceptance, psychological flexibility, positive affect, and positive social relations.
TL;DR: In this paper, the authors proposed and tested a theoretical model of the impact of formal and informal socialization mechanisms on the level of knowledge sharing within interorganizational product development projects and the subsequent effect on buyer firm performance.
TL;DR: It is shown that although dengue virus type 2 (DENV2) infection of Ae.
Abstract: A number of studies have shown that both innate and adaptive immune defense mechanisms greatly influence the course of human dengue virus (DENV) infections, but little is known about the innate immune response of the mosquito vector Aedes aegypti to arbovirus infection. We present evidence here that a major component of the mosquito innate immune response, RNA interference (RNAi), is an important modulator of mosquito infections. The RNAi response is triggered by double-stranded RNA (dsRNA), which occurs in the cytoplasm as a result of positive-sense RNA virus infection, leading to production of small interfering RNAs (siRNAs). These siRNAs are instrumental in degradation of viral mRNA with sequence homology to the dsRNA trigger and thereby inhibition of virus replication. We show that although dengue virus type 2 (DENV2) infection of Ae. aegypti cultured cells and oral infection of adult mosquitoes generated dsRNA and production of DENV2-specific siRNAs, virus replication and release of infectious virus persisted, suggesting viral circumvention of RNAi. We also show that DENV2 does not completely evade RNAi, since impairing the pathway by silencing expression of dcr2, r2d2, or ago2, genes encoding important sensor and effector proteins in the RNAi pathway, increased virus replication in the vector and decreased the extrinsic incubation period required for virus transmission. Our findings indicate a major role for RNAi as a determinant of DENV transmission by Ae. aegypti.