Host Resources Research Articles

Coinfection with a virus constrains within-host infection load but increases transmission potential of a highly virulent fungal plant pathogen.

The trade‐off between within‐host infection rate and transmission to new hosts is predicted to constrain pathogen evolution, and to maintain polymorphism in pathogen populations. Pathogen life‐history stages and their correlations that underpin infection development may change under coinfection with other parasites as they compete for the same limited host resources. Cross‐kingdom interactions are common among pathogens in both natural and cultivated systems, yet their impacts on disease ecology and evolution are rarely studied. The host plant Plantago lanceolata is naturally infected by both Phomopsis subordinaria, a seed killing fungus, as well as Plantago lanceolata latent virus (PlLV) in the Åland Islands, SW Finland. We performed an inoculation assay to test whether coinfection with PlLV affects performance of two P. subordinaria strains, and the correlation between within‐host infection rate and transmission potential. The strains differed in the measured life‐history traits and their correlations. Moreover, we found that under virus coinfection, within‐host infection rate of P. subordinaria was smaller but transmission potential was higher compared to strains under single infection. The negative correlation between within‐host infection rate and transmission potential detected under single infection became positive under coinfection with PlLV. To understand whether within‐host and between‐host dynamics are correlated in wild populations, we surveyed 260 natural populations of P. lanceolata for P. subordinaria infection occurrence. When infections were found, we estimated between‐hosts dynamics by determining pathogen population size as the proportion of infected individuals, and within‐host dynamics by counting the proportion of infected flower stalks in 10 infected plants. In wild populations, the proportion of infected flower stalks was positively associated with pathogen population size. Jointly, our results suggest that the trade‐off between within‐host infection load and transmission may be strain specific, and that the pathogen life‐history that underpin epidemics may change depending on the diversity of infection, generating variation in disease dynamics.

Ecological Opportunity and Necessity: Biotic and Abiotic Drivers Interact During Diversification of Digital Host-Parasite Communities

Most of Earth’s diversity has been produced in rounds of adaptive radiation, but the ecological drivers of diversification, such as abiotic complexity (i.e.,ecological opportunity) or predation and parasitism (i.e.,ecological necessity), are hard to disentangle. However, most of these radiations occurred hundreds of thousands if not millions of years ago, and the mechanisms promoting contemporary coexistence are not necessarily the same mechanisms that drove diversification in the first place. Experimental evolution has been one fruitful approach used to understand how different ecological mechanisms promote diversification in simple microbial microcosms, but these microbial systems come with their own limitations. To test how ecological necessity and opportunity interact, we use an unusual system of self-replicating computer programs that diversify to fill niches in a virtual environment. These organisms are subject to ecological pressures just like their natural counterparts. They experience biotic interactions from digital parasites, which steal host resources to replicate their own code and spread in the population. With the control afforded by experimenting with computational ecologies, we begin to unweave the complex interplay between ecological drivers of diversification. In particular, we find that the complexity of the abiotic environment and the size of the phenotypic space in which organisms are able to interact play different roles depending on the ecological driver of diversification. We find that in some situations, both ecological opportunity and necessity drive similar levels of diversity. However, the phenotypes that hosts uncover while coevolving with parasites are dramatically more complex than hosts evolving alone.

Disruption of carbon for nutrient exchange between potato and arbuscular mycorrhizal fungi enhanced cyst nematode fitness and host pest tolerance.

Summary Plants simultaneously interact with a range of biotrophic symbionts, ranging from mutualists such as arbuscular mycorrhizal fungi (AMF), to parasites such as the potato cyst nematode (PCN). The exchange of mycorrhizal‐acquired nutrients for plant‐fixed carbon (C) is well studied; however, the impact of competing symbionts remains underexplored.In this study, we examined mycorrhizal nutrient and host resource allocation in potato with and without AMF and PCN using radioisotope tracing, whilst determining the consequences of such allocation.The presence of PCN disrupted C for nutrient exchange between plants and AMF, with plant C overwhelmingly obtained by the nematodes. Despite this, AMF maintained transfer of nutrients on PCN‐infected potato, ultimately losing out in their C for nutrient exchange with the host. Whilst PCN exploited the greater nutrient reserves to drive population growth on AMF–potato, the fungus imparted tolerance to allow the host to bear the parasitic burden.Our findings provide important insights into the belowground dynamics of plant–AMF symbioses, where simultaneous nutritional and nonnutritional benefits conferred by AMF to hosts and their parasites are seldom considered in plant community dynamics. Our findings suggest this may be a critical oversight, particularly in the consideration of C and nutrient flows in plant and soil communities.

A case of convergent evolution: Several viral and bacterial pathogens hijack RSK kinases through a common linear motif

Microbes have been coevolving with their host for millions of years, exploiting host resources to their own benefit. We show that viral and bacterial pathogens convergently evolved to hijack cellular mitogen-activated protein kinase (MAPK) p90-ribosomal S6-kinases (RSKs). Theiler's virus leader (L) protein binds RSKs and prevents their dephosphorylation, thus maintaining the kinases active. Recruitment of RSKs enables L-protein-mediated inhibition of eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2 or PKR) and stress granule formation. Strikingly, ORF45 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) and YopM protein of Yersinia use the same peptide motif as L to recruit and activate RSKs. All three proteins interact with a conserved surface-located loop of RSKs, likely acting as an allosteric regulation site. Some unrelated viruses and bacteria thus evolved to harness RSKs in a common fashion, yet to target distinct aspects of innate immunity. As documented for Varicella zoster virus ORF11, additional pathogens likely evolved to hijack RSKs, using a similar short linear motif.

Utilisation-aware VM placement policy for workload consolidation in cloud data centres

In recent years, the demand for cloud services has risen. Data centres must have a growing number of servers to accommodate rising demand for cloud services, and data centres consume a lot of energy. Virtual machine consolidation (VMC) is a strategy for reducing energy consumption in data centres by shutting down underutilised servers while maintaining service levels (SLA). The VMC process is separated into four policies: overloaded host detection, underloaded host detection, virtual machine selection, and virtual machine deployment. The utilisation-aware VM placement (UAVMP) technique is presented in this research work, which efficiently selects the destination host for VMs migrating from overload/underload hosts based on the host's utilisation and resource skewness. The performance is assessed using the CloudSim simulator. When we compare UAVMP results with power-aware best fit decreasing (PABFD), modified best fit decreasing (MBFD), first fit (FF) and least fit (LF), we find that UAVMP outperforms all.

Infection by dsRNA viruses is associated with enhanced sporulation efficiency in Saccharomyces cerevisiae.

Upon starvation diploid cells of the facultative sexual yeast Saccharomyces cerevisiae undergo sporulation, forming four metabolically quiescent and robust haploid spores encased in a degradable ascus. All endosymbionts, whether they provide net benefits or costs, utilize host resources; in yeast, this should induce an earlier onset of sporulation. Here, we tested whether the presence of endosymbiotic dsRNA viruses (M satellite and L‐A helper) correspond with higher sporulation rate of their host, S. cerevisiae. We find that S. cerevisiae hosting both the M and L‐A viruses (so‐called “killer yeasts”) have significantly higher sporulation efficiency than those without. We also found that the removal of the M virus did not reduce sporulation frequency, possibly because the L‐A virus still utilizes host resources with and without the M virus. Our findings indicate that either virulent resource use by endosymbionts induces sporulation, or that viruses are spread more frequently to sporulating strains. Further exploration is required to distinguish cause from effect.

'Candidatus Liberibacter' Pathosystems at the Forefront of Agricultural and Biological Research Challenges.

'Candidatus Liberibacter' Pathosystems at the Forefront of Agricultural and Biological Research Challenges.

A parasitoid's dilemma between food and host resources: the role of volatiles from nectar-providing marigolds and host-infested plants attracting Aphidius platensis.

The use of nectar-producing companion plants in crops is a well-known strategy of conserving natural enemies in biological control. However, the role of floral volatiles in attracting parasitoids and effects on host location via herbivore-induced plant volatiles is poorly known. Here, we examined the role of floral volatiles from marigold (Tagetes erecta), alone or in combination with volatiles from sweet pepper plant (Capsicum annuum), in recruiting Aphidius platensis, an important parasitoid of the green peach aphid Myzus persicae. We also investigated whether marigold floral volatiles are more attractive to the parasitoid than those emitted by sweet pepper plants infested by M. persicae. Olfactometry assays indicated that floral volatiles attracted A. platensis to the marigold plant and are more attractive than sweet pepper plant volatiles. However, volatiles emitted by aphid-infested sweet pepper were as attractive to the parasitoid as those of uninfested or aphid-infested blooming marigold. The composition of volatile blends released by uninfested and aphid-infested plants differed between both blooming marigold and sweet pepper, but the parasitoid did not discriminate aphid-infested from uninfested blooming marigold. Volatile released from blooming marigold and sweet pepper shared several compounds, but that of blooming marigold contained larger amounts of fatty-acid derivatives and a different composition of terpenes. We discuss the potential implications of the aphid parasitoid attraction in a diversified crop management strategy.

Freshwater disease hotspots: Drivers of fine‐scale spatial heterogeneity in trematode parasitism in streams

AbstractPopulations of stream organisms often show large heterogeneity in space, which can substantially influence community dynamics and ecosystem functioning. However, few studies have examined spatial heterogeneity of parasites in lotic ecosystems, especially at fine spatial scales (e.g., within stream reaches).We quantified parasite infections in 3,255 host snails (Juga plicifera) at 1‐m intervals along three second‐order stream reaches to examine relationships between trematode parasite infections, fine‐scale heterogeneity in host characteristics (density and size), and the stream environment (depth, allochthonous materials, flow velocity, and substrate rugosity). We then conducted a field experiment to specifically test the effect of resource heterogeneity in the form of leaf litter on trematode densities (i.e., infected snails per unit area), which represents a measure of local disease risk to secondary hosts. We hypothesised that variation in bottom‐up effects of host resources to snail hosts to parasites would drive spatial heterogeneity in trematode density.In the field surveys, trematode density ranged from 0 to 80 infected snails/m2 and showed spatial autocorrelation within two of three stream reaches. Trematode density increased with snail density, which was positively related with the amount of allochthonous materials but negatively related to steam depth. Individual host infection probability increased with snail size, which was positively related to both allochthonous materials and stream depth.In the experiment, host snail and trematode densities increased by 3‐fold and 4‐fold, respectively, in the leaf addition treatments relative to controls. The experiment therefore provided mechanistic understanding of patterns from the surveys by demonstrating a bottom‐up effect from high quality resources to host space use to trematode density.Our results demonstrate a strong role of within‐reach variation in allochthonous resources and habitat (depth) in driving spatial heterogeneity of stream parasites, which probably creates fine‐scale hotspots of disease transmission to downstream hosts. More broadly, our findings help integrate parasites into our understanding of how environmental heterogeneity influences community structure and ecosystem processes (e.g., disease risk) in streams.

Woody plant encroachment and the ecology of vector‐borne diseases

Abstract Vector‐borne diseases (VBDs) impact human and animal health globally, and their ecology and transmission are affected by human‐caused ecosystem and biome transitions. Woody plant encroachment (WPE), a top driver of biome and land cover transitions in grasslands and savannas of the world, greatly changes abiotic conditions, vegetation and animal populations and communities. Although these effects mirror mechanisms by which other ecosystem and land cover changes influence VBD ecology, few studies have evaluated if WPE expands distributions and increases the transmission of VBDs. We develop a conceptual framework for WPE effects on VBDs by synthesizing key literature on these topics and on impacts of land cover change on diseases broadly. We also present examples of WPE systems from two continents illustrating documented and likely effects on VBD systems, and we outline a prospectus for future research evaluating such effects. This synthesis highlights the potential for WPE to increase the transmission of VBDs world‐wide. WPE's effects on landscape composition, local vegetation, abiotic conditions, and vector and host resources, interactions and population and community processes, likely impact VBD distributions, transmission and health outcomes. Much additional research is needed on topics like the effects of WPE management on health risks associated with VBDs. Synthesis and applications. Woody plant encroachment (WPE) is drastically changing grasslands and savannas world‐wide. Its well‐documented influences on abiotic conditions (e.g. temperature and humidity), vegetation and wildlife are having previously underappreciated effects on the ecology of vector‐borne diseases, likely increasing spatial distributions and transmission of diseases. Management to reduce WPE is ongoing in much of the world due to its degradation of ecosystem services like biodiversity, livestock production and water quality and quantity. The ecosystem disservice of elevated disease risk in humans, wildlife and domestic animals should be an additional consideration when making land management and policy decisions related to WPE.

Differential temperature responses between Plutella xylostella and its specialist endo-larval parasitoid Diadegma semiclausum-Implications for biological control.

Understanding the thermal dynamics of host-parasitoid interactions is crucial to predicting how biological control of pest insects by parasitoids might be affected by geographic location and climate change. We compared performance traits of Plutella xylostella (Lepidoptera: Plutellidae) and its solitary endo-larval parasitoid Diadegma semiclausum (Hymenoptera: Ichneumonidae), over a wide range of constant rearing temperatures (10-30°C). Parasitoids reared at 30°C experienced reductions in pupation rate, pupal mass, egg load, and adult life span when compared with those reared at lower temperatures. Our analyses of the fate of parasitoids and their hosts and intergenerational population growth at different rearing temperatures show that D. semiclausum and P. xylostella respond differently to temperature, leading to divergent outcomes under different temperature conditions. Some parasitoid larvae could not complete development at 30°C, the temperature at which the host biomass was least and the metabolic demands of the parasitoid could be high, suggesting that parasitoid development might be constrained by lack of host resources at higher temperatures. We discuss the potential mechanisms of parasitoid susceptibility to elevated temperatures, which likely explain the pronounced seasonal dynamics of D. semiclausum in subtropical regions and its failure to establish in lowland tropical regions, where P. xylostella is a serious pest. Similar interactions in other host-parasitoid associations would constrain the efficacy of parasitoids as biological control agents as global temperatures increase.

Implications of mistletoe parasitism for the host metabolome: A new plant identity in the forest canopy.

Mistletoe-host systems exemplify an intimate and chronic relationship where mistletoes represent protracted stress for hosts, causing long-lasting impact. Although host changes in morphological and reproductive traits due to parasitism are well known, shifts in their physiological system, altering metabolite concentrations, are less known due to the difficulty of quantification. Here, we use ecometabolomic techniques in the plant-plant interaction, comparing the complete metabolome of the leaves from mistletoe (Viscum album) and needles from their host (Pinus nigra), both parasitized and unparasitized, to elucidate host responses to plant parasitism. Our results show that mistletoe acquires metabolites basically from the primary metabolism of its host and synthesizes its own defence compounds. In response to mistletoe parasitism, pines modify a quarter of their metabolome over the year, making the pine canopy metabolome more homogeneous by reducing the seasonal shifts in top-down stratification. Overall, host pines increase antioxidant metabolites, suggesting oxidative stress, and also increase part of the metabolites required by mistletoe, which act as a permanent sink of host resources. In conclusion, by exerting biotic stress and thereby causing permanent systemic change, mistletoe parasitism generates a new host-plant metabolic identity available in forest canopy, which could have notable ecological consequences in the forest ecosystem.

Reservoir hosts experiencing food stress alter transmission dynamics for a zoonotic pathogen.

Food limitation is a universal stressor for wildlife populations and is increasingly exacerbated by human activities. Anthropogenic environmental change can significantly alter the availability and quality of food resources for reservoir hosts and impact host–pathogen interactions in the wild. The state of the host's nutritional reserves at the time of infection is a key factor influencing infection outcomes by altering host resistance. Combining experimental and model-based approaches, we investigate how an environmental stressor affects host resistance to West Nile virus (WNV). Using American robins (Turdus migratorius), a species considered a superspreader of WNV, we tested the effect of acute food deprivation immediately prior to infection on host viraemia. Here, we show that robins food deprived for 48 h prior to infection, developed higher virus titres and were infectious longer than robins fed normally. To gain an understanding about the epidemiological significance of food-stressed hosts, we developed an agent-based model that simulates transmission dynamics of WNV between an avian host and the mosquito vector. When simulating a nutritionally stressed host population, the mosquito infection rate rose significantly, reaching levels that represent an epidemiological risk. An understanding of the infection disease dynamics in wild populations is critical to predict and mitigate zoonotic disease outbreaks.

Probing the spatiotemporal patterns of HBV multiplication reveals novel features of its subcellular processes.

Through evolution, Hepatitis B Virus (HBV) developed highly intricate mechanisms exploiting host resources for its multiplication within a constrained genetic coding capacity. Yet a clear picture of viral hitchhiking of cellular processes with spatial resolution is still largely unsolved. Here, by leveraging bDNA-based fluorescence in situ hybridization (FISH) combined with immunofluorescence, we developed a microscopic approach for multiplex detection of viral nucleic acids and proteins, which enabled us to probe some of the key aspects of HBV life cycle. We confirmed the slow kinetics and revealed the high variability of viral replication at single-cell level. We directly visualized HBV minichromosome in contact with acetylated histone 3 and RNA polymerase II and observed HBV-induced degradation of Smc5/6 complex only in primary hepatocytes. We quantified the frequency of HBV pregenomic RNAs occupied by translating ribosome or capsids. Statistics at molecular level suggested a rapid translation phase followed by a slow encapsidation and maturation phase. Finally, the roles of microtubules (MTs) on nucleocapsid assembly and virion morphogenesis were analyzed. Disruption of MTs resulted in the perinuclear retention of nucleocapsid. Meanwhile, large multivesicular body (MVB) formation was significantly disturbed as evidenced by the increase in number and decrease in volume of CD63+ vesicles, thus inhibiting mature virion secretion. In conclusion, these data provided spatially resolved molecular snapshots in the context of specific subcellular activities. The heterogeneity observed at single-cell level afforded valuable molecular insights which are otherwise unavailable from bulk measurements.

A methodology for selecting hardware performance counters for supporting non-intrusive diagnostic of flood DDoS attacks on web servers

Web server outages caused by a Distributed Denial of Service (DDoS) attacks have increased considerably over the years. Intrusion Detection Systems (IDS) are not sufficient to detect threats in the system, even when used in conjunction with Intrusion Prevention Systems (IPS) and even considering the use of data sets containing information about typical situations and attacks on the system’s service. Performing analyzes with a very dense amount of observed variables can cost a significant amount of host resources. Furthermore, these data sets are at risk of not representing the system’s behavior properly, and they cannot always be shared as they may contain confidential information in the diagnostic data. This paper presents a non-intrusive diagnostic methodology to select hardware performance counters in HTTP flood DDoS attacks on enterprise-level web servers, combining methods and techniques from different segments. The proposed approach uses low-level resource appliances such as Hardware Performance Counters (HPCs) for diagnosis, creating behavioral profiles in the face of attacks and usual service usage. The proposed strategy supports delivering reliable diagnoses with accurate characterization without third-party data sets. With the proposed methodology, we were able to reduce HPCs by 26%, compared to the initial group.

Degradation of host translational machinery drives tRNA acquisition in viruses.

Viruses are traditionally thought to be under selective pressure to maintain compact genomes and thus depend on host cell translational machinery for reproduction. However, some viruses encode abundant tRNA and other translation-related genes, potentially optimizing for codon usage differences between phage and host. Here, we systematically interrogate selective advantages that carrying 18 tRNAs may convey to a T4-like Vibriophage. Host DNA and RNA degrade upon infection, including host tRNAs, which are replaced by those of the phage. These tRNAs are expressed at levels slightly better adapted to phage codon usage, especially that of late genes. The phage is unlikely to randomly acquire as diverse an array of tRNAs as observed (p= 0.0017). Together, our results support that the main driver behind phage tRNA acquisition is pressure to sustain translation as host machinery degrades, a process resulting in a dynamically adapted codon usage strategy during the course of infection.

Correlated evolution of fish host length and parasite spore size: a tale from myxosporeans inhabiting elasmobranchs

Myxozoa represent a diverse group of microscopic cnidarian endoparasites alternating between invertebrate and vertebrate hosts. Of the approximately 2,600 species described predominantly from teleost fish, only 1.8% have been reported from cartilaginous fishes (Elasmobranchii). As ancestral vertebrate hosts of myxozoans, elasmobranchs may have played an important role in myxozoan evolution, however, they are also some of the largest vertebrate hosts known for this group of parasites. We screened 50 elasmobranchs belonging to nine species and seven families, from various geographical areas, for myxozoan infection. We found a 22% overall prevalence of myxozoans in elasmobranchs and describe five species new to science. We investigated, for the first known time, the evolution of spore size within three phylogenetic clades, Ceratomyxa, Sphaerospora sensu stricto and Parvicapsula. We found that spores from elasmobranch-infecting myxozoans were on average 4.8× (Ceratomyxa), 2.2× (Parvicapsula clade) and 1.8× (Sphaerospora sensu stricto except polysporoplasmic Sphaerospora spp.) larger than those from teleosts. In all analysed clades, spore size was correlated with phylogenetic position. In ceratomyxids, it was further strongly positively correlated with fish body size and habitat depth, independent of cellular composition of the spores and phylogenetic position in the tree. While in macroparasites a host size-correlated increase in parasite size occurs on a large scale and is often related to improved exploitation of host resources, in microscopic parasites size ranges vary at the scale of a few micrometres, disproportionate to the available additional space in a large host. We discuss the ecological role of these changes with regard to transmission under high pressure and an invertebrate fauna that is adapted to deeper marine habitats.

Butterfly diversity in relation to host and nectar food plants in TNAU Botanical Garden, Coimbatore

Aim: The present study was undertaken to assess the food resources and butterfly diversity in Botanical Garden, Tamil Nadu Agricultural University. Methodology: The survey was conducted in targeted locality from September 2015 – October 2019 and butterflies sightings were recorded using a digital camera (Nikon D7200 with kit lens 18-105 mm, Tamron 200-300 apo dg macro lens). Results: Total 95 species of butterflies were recorded in the garden. Among all families, the highest count was observed in Nymphalidae family followed by Lycaenidae (29 species), Pieridae (15 species), Hesperiidae (10 species) and Papilionidae (11 species). The relative diversity of Nymphalidae (31.57 %) and Lycaenidae (30.52 %) were higher. For Pieridae, RD value accounted for 15.78 % and 11.57 % for Papilionidae. RD value was least for Hesperiidae family (10.52 %). Out of 95 butterflies, the host plants of 88 butterflies were present in the garden itself. Fifteen nectar plants belonging to eleven families were most preferred nectar sources. Interpretation: The present study gives information of butterfly and its food plant diversity in the garden. The obtained information will help in planting additional host and nectar plant resources to attract rare species. It also sheds light on the importance of survival of prominent nectar plants throughout the year for maintaining the butterfly abundance in garden.

Large graph convolutional network training with GPU-oriented data communication architecture

Graph Convolutional Networks (GCNs) are increasingly adopted in large-scale graph-based recommender systems. Training GCN requires the minibatch generator traversing graphs and sampling the sparsely located neighboring nodes to obtain their features. Since real-world graphs often exceed the capacity of GPU memory, current GCN training systems keep the feature table in host memory and rely on the CPU to collect sparse features before sending them to the GPUs. This approach, however, puts tremendous pressure on host memory bandwidth and the CPU. This is because the CPU needs to (1) read sparse features from memory, (2) write features into memory as a dense format, and (3) transfer the features from memory to the GPUs. In this work, we propose a novel GPU-oriented data communication approach for GCN training, where GPU threads directly access sparse features in host memory through zero-copy accesses without much CPU help. By removing the CPU gathering stage, our method significantly reduces the consumption of the host resources and data access latency. We further present two important techniques to achieve high host memory access efficiency by the GPU: (1) automatic data access address alignment to maximize PCIe packet efficiency, and (2) asynchronous zero-copy access and kernel execution to fully overlap data transfer with training. We incorporate our method into PyTorch and evaluate its effectiveness using several graphs with sizes up to 111 million nodes and 1.6 billion edges. In a multi-GPU training setup, our method is 65--92% faster than the conventional data transfer method, and can even match the performance of all-in-GPU-memory training for some graphs that fit in GPU memory.

Genetic-Based Task Scheduling Algorithm with Dynamic Virtual Machine Generation in Cloud Computing

Recently, cloud computing has become the most common platform in the computing world. scheduling is one of the most important mechanism for managing cloud resources. Scheduling mechanism is a mechanism for scheduling user tasks among datacenters, host and virtual machines (VMs) and is an NP completeness problem. Most of existing mechanisms are heuristic and meta-heuristic methods, developed to address a part of scheduling problem and did not consider the dynamic creation of VMs by taking into account the required resources for a user task and the capabilities of a set of available hosts. To deal with this dynamic behavior, this paper introduces a new mechanism that uses a genetic algorithm (GA) for establishing a flexible scheduling mechanism that can adapt the dynamic number of VMs based on the required resources by user tasks and the available resources of hosts. Simulation results show that the proposed algorithm can distribute any number of user tasks on the available resources and it achieves better performance than existing algorithms in terms of response time, makespan, FlowTime, throughput, and resource utilization.