Hybrid Worms Research Articles

From the Dialectical Perspective: Modeling and Exploiting of Hybrid Worm Propagation

The hierarchical network is the more effective platform, which provides multiple channels for various worm propagation. Thus, emerging worms can infect vulnerable hosts by scanning strategy and social media. However, the spread of scan-based worm is restrained due to uneven distribution of vulnerable hosts and NAT (Network Address Translation) technique. Meanwhile, topological dependency dictates to topology-based worm only infecting those hosts in social networks. To avoid their respective disadvantages, modern hybrid worm, which combines the above two propagation mechanisms, can implement efficient IP-address scanning by enhanced combination-scanning strategy, and spread more aggressively in social networks using enhanced reinfection mechanism. This paper presents a Hierarchical-Stochastic Propagation model to understand hybrid worm propagation. Inspired by hybrid worm, we design a new vaccine based on the Hierarchical-Measure Immunization strategy. For physical networking layer, we can estimate vulnerable-host distribution to find vulnerable hosts effectively through Maximum Likelihood estimation. For social networking layer, we use a novel propagation centrality measure to discover vital social nodes accurately. The experimental results show that our model can characterize the propagation mechanism of hybrid worms more comprehensively, and greatly outperforms state of the art models in terms of estimation accuracy. Meanwhile, our strategy is more effective to restrain the hybrid worm from spreading in networks.

Selection of partenogenetic clones for mixing with fine silkworm breeds in the conditions of Uzbekistan

The creation and introduction into production of new breeds and hybrids that meet the needs of the world market and industrial enterprises through the development of selection methods for breeding stations and seed enterprises is of great scientific and practical importance. In this regard, the work of a number of local and international scientists is devoted to the selection and creation of new breeds and hybrids of mulberry silkworm on the basis of leading selection traits. The effectiveness of the artificial parthenogenesis method developed in our laboratory is that the effect applied suppresses the reduction division of egg cells. Also, the parthenogenetic genus immediately receives the same set of chromosomes and genes. However, ♀ clone × ♂ hybrid worms have a high viability, the cocoons are the same in shape and other characteristics, there is no work on the separation of the primary parent breed (parthenoclonus) for hybridization (because it consists of 100% only females), breeding at all stages work is not done (because all parthenoclon females are genetically the same and do not change by generation). It is also possible to obtain all the cocoons of parthenoclon in the extraction of cocoons, as their genetic homogeneity completely eliminates the sorting of cocoons in breeding stations and seed plants.

Nutrition assessment of new created mulberry varieties

This research was aimed at establishing high-quality and abundant cocoon cultivation in the country, to create new high-quality and nutritious mulberry varieties and gradually introduce them into production. In order to create local mulberry varieties, for the first time the viability of mulberry silkworm hybrids of mulberry varieties “Jararik-9”, “Jararik-10” was determined by the level of cocoon productivity and technological impact. The coefficient of leaves eating of new varieties of mulberry “Jararik-9”, “Jararik-10” by hybrid worms of silkworm was determined. The varieties of mulberry belonging to the genusMorus alba L.and hybrids belonging to the genusBombyx mori Lof the mulberry silkworm were taken as the study objects. For chemical analysis, leaf samples were taken and analyzed in the spring in the order established by the worms in the middle of the 5th year of development. Furthermore, the effect of new mulberry varieties on the growth dynamics of worm leaves was studied. The coefficient of leaves eating of new mulberry varieties by hybrid worms was determined. According to the results of the research, among the new selection numbers No3-02 and No7-02, the coefficient of assimilation of No3-02 and No7-02 is significantly higher than other selection numbers and “Tajik seedless” variety.

Epidemic Heterogeneity and Hierarchy: A Study of Wireless Hybrid Worm Propagation

With the growth in the use of smart mobile devices and the development of information technologies, worms and malware can spread from mobile networks into heterogeneous and hierarchical networks. Thus, the spread of these worms constitutes an increasing potential threat. For understanding the propagation of the aforementioned wireless hybrid worms, current researches have three critical problems: <i>Structural simplification of network topologies</i> (previous research object for wireless worms is the mobile network), <i>Homogenous population of network devices</i> (properties of network devices are the same), and <i>Inaccuracy of propagation models</i> (traditional deterministic differential or stochastic difference models cannot model propagation of wireless hybrid worms accurately). To address them, we propose a novel compartmental population-based propagation model oriented towards heterogeneous and hierarchical networks with human behaviors, and then study the impacts of user mobility and operation behaviors on worm propagation. Meanwhile, we conduct extensive simulations to show our model can characterize propagation features accurately. The results in this paper not only provide a deep understanding of new worm propagation, but also serve as fundamental defense guidelines.

CC2: Defending Hybrid Worm on Mobile Networks with Two‐Dimensional Circulation Control

As the hybrid worm can propagate by both personal social interactions and wireless communications, it has been identified as one of the most severe threats to the mobile Internet. This problem is expected to become worse with the boom of social applications and mobile services. In this work, we study the propagation dynamics of hybrid worms and propose a systematic countermeasure. The system maintains a set of community structure which describes the high‐speed infection zone of worms and contains worm propagation by distributing the worm signature to the guard nodes selected from the periphery of each community. For those nodes that are geographically close but located in different communities , we evaluate the communication security between them based on the observed infection history and limit communications between insecure ones to avoid the worm spreading across communities. We also design an efficient worm signature forwarding strategy that enables most nodes in the network to reach an immune state before being infected by the worm. Extensive real‐trace driven simulations verify the feasibility and effectiveness of the proposed methods.

Genetic evidence for hybridisation between Haemonchus contortus and Haemonchus placei in natural field populations and its implications for interspecies transmission of anthelmintic resistance

Genetic hybridisation between parasitic nematode species has potentially important consequences. It could lead to the introgression of genes between species including those involved in pathogenicity, host specificity, transmission and drug resistance. It could also complicate diagnosis and control. However, there are few compelling examples of its occurrence in parasites in the field. Haemonchus contortus and Haemonchus placei are two closely related parasitic nematode species that predominantly infect small ruminants and cattle, respectively. They are capable of experimental hybridisation when adult worms of each species are transplanted into the same individual host. Given that co-infection occurs in both small ruminants and cattle, there is potential for hybridisation in the field. However, this has not been definitively demonstrated and its extent is unknown. We investigated the occurrence of co-infection and interspecies hybridisation in H. contortus and H. placei in field populations from small ruminants from Pakistan and southern India using a number of independent genetic markers. Haemonchus contortus and H. placei co-infections were common in Pakistan but not in southern India where H. placei appeared to be absent in small ruminant hosts. In the former region, a number of worms were identified that were heterozygous for fixed, species-specific rDNA internal transcribed spacer 2 (ITS-2) single nucleotide polymorphisms. Genotyping of these ITS-2 heterozygotes with an additional four nuclear markers conclusively demonstrated them to be F1 interspecies hybrids. Mitochondrial NADH dehydrogenase subunit 4 haplotype analysis demonstrated that four of the hybrid worms had a H. placei maternal parent and one had a H. contortus maternal parent showing that hybridisation could occur in either direction. Interestingly, one of these hybrids contained an H. contortus isotype-1 β-tubulin benzimidazole resistance allele, suggesting there is a potential for interspecies introgression of drug resistance loci. We believe this is the first definitive genetic evidence of hybridisation between H. contortus and H. placei in the field and represents the most comprehensive genetic evidence of F1 hybrids between any human or livestock parasitic nematode species to date. Further, it suggests that interspecies transmission of anthelmintic resistance mutations warrants further investigation.

Introgressive Hybridization of Schistosoma haematobium Group Species in Senegal: Species Barrier Break Down between Ruminant and Human Schistosomes

BackgroundSchistosomes are dioecious parasitic flatworms, which live in the vasculature of their mammalian definitive hosts. They are the causative agent of schistosomiasis, a disease of considerable medical and veterinary importance in tropical and subtropical regions. Schistosomes undergo a sexual reproductive stage within their mammalian host enabling interactions between different species, which may result in hybridization if the species involved are phylogenetically close. In Senegal, three closely related species in the Schistosoma haematobium group are endemic: S. haematobium, which causes urogenital schistosomiasis in humans, and S. bovis and S. curassoni, which cause intestinal schistosomiasis in cows, sheep and goats.Methodology/Principal FindingsLarge-scale multi-loci molecular analysis of parasite samples collected from children and domestic livestock across Senegal revealed that interactions and hybridization were taking place between all three species. Evidence of hybridization between S. haematobium/S. curassoni and S. haematobium/S. bovis was commonly found in children from across Senegal, with 88% of the children surveyed in areas of suspected species overlap excreting hybrid miracidia. No S. haematobium worms or hybrids thereof were found in ruminants, although S. bovis and S. curassoni hybrid worms were found in cows. Complementary experimental mixed species infections in laboratory rodents confirmed that males and females of each species readily pair and produce viable hybrid offspring.Conclusions/SignificanceThese data provide indisputable evidence for: the high occurrence of bidirectional hybridization between these Schistosoma species; the first conclusive evidence for the natural hybridisation between S. haematobium and S. curassoni; and demonstrate that the transmission of the different species and their hybrids appears focal. Hybridization between schistosomes has been known to influence the disease epidemiology and enhance phenotypic characteristics affecting transmission, morbidity and drug sensitivity. Therefore, understanding and monitoring such inter-species interactions will be essential for optimizing and evaluating control strategies across such potential hybrid zones.

Agent‐based modeling of malware dynamics in heterogeneous environments

ABSTRACTThe increasing convergence of power‐law networks such as social networking and peer‐to‐peer applications, web‐delivered applications, and mobile platforms makes today's users highly vulnerable to entirely new generations of malware that exploit vulnerabilities in web applications and mobile platforms for new infections, while using the power‐law connectivity for finding new victims. The traditional epidemic models based on assumptions of homogeneity, average‐degree distributions, and perfect‐mixing are inadequate to model this type of malware propagation. In this paper, we study four aspects crucial to modeling malware propagation: application‐level interactions among users of such networks, local network structure, user mobility, and network coordination of malware such as botnets. Since closed‐form solutions of malware propagation considering these aspects are difficult to obtain, we describe an open‐source, flexible agent‐based emulation framework that can be used by malware researchers for studying today's complex malware. The framework, called Agent‐Based Malware Modeling (AMM), allows different applications, network structure, network coordination, and user mobility in either a geographic or a logical domain to study various infection and propagation scenarios. In addition to traditional worms and viruses, the framework also allows modeling network coordination of malware such as botnets. The majority of the parameters used in the framework can be derived from real‐life network traces collected from a network, and therefore, represent realistic malware propagation and infection scenarios. As representative examples, we examine two well‐known malware spreading mechanisms: (i) a malicious virus such as Cabir spreading among the subscribers of a cellular network using Bluetooth and (ii) a hybrid worm that exploit email and file‐sharing to infect users of a social network. In both cases, we identify the parameters most important to the spread of the epidemic based upon our extensive simulation results. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Genetic diversity of Echinococcus multilocularis on a local scale

Echinococcus multilocularis is the causative agent of human Alveolar Echinococcosis (AE), and it is one of the most lethal zoonotic infections in the Northern Hemisphere. In France, the eastern and central regions are endemic areas; Franche-Comté, Lorraine and Auvergne are particularly contaminated. Recently, several human cases were recorded in the French Ardennes area, a region adjacent to the western border of the E. multilocularis range in France. A previous study in this focus described a prevalence of over 50% of the parasite in red foxes. The present study investigated the genetic diversity of adult worms collected from foxes in a 900 km 2 area in the Ardennes. Instead of a conventional mitochondrial target (ATP6), two microsatellite targets (EmsB and NAK1) were used. A total of 140 adult worms isolated from 25 red foxes were genotyped. After hierarchical clustering analyses, the EmsB target enabled us to distinguish two main assemblages, each divided into sub-groups, yielding the differentiation of six clusters or assemblage profiles. Thirteen foxes (52% of the foxes) each harbored worms from at least two different assemblage profiles, suggesting they had become infected by several sources. Using the NAK1 target, we identified 3 alleles, two found in association with the two EmsB assemblages. With the NAK1 target, we investigated the parasite breeding system and the possible causes of genetic diversification. Only one fox harbored hybrid worms, indicative of a possible (and rare) occurrence of recombination, although multiple infections have been observed in foxes. These results confirm the usefulness of microsatellite targets for assessing genetic polymorphism in a geographically restricted local range.

Hybrid Worms

Computers today are evolving at a much faster rate than anyone could have imagined, with processor speeds doubling around every six months. The same phenomenal speed of development applies to virtually every area of computing, therefore it’s unsurprising that hacking tools and malicious code are developing at a comparable pace.

Experimental hybridization between Oesophagostomum dentatum and O. quadrispinulatum in pigs.

To investigate eventual hybridization between two nodular worm species of pigs, Oesophagostomum dentatum and O. quadrispinulatum, we used either mature, adult worms or 10-day-old fourth-stage larvae (L4) as starting material, employing a nonsurgical transplantation technique. Following the transfer of adult worms the ensuing first generation of larvae gave rise to adult worms that were found by morphological examination to be purely O. dentatum. Therefore, we decided to use the immature L4 as starting material. After the transfer of L4 to recipient pigs, fecal cultures were established and the L3 derived from the O. dentatum male O. quadrispinulatum female cross gave rise to adult but infertile worms, which morphologically had the sexual characters of their parent generation, whereas other characteristics were intermediate between the two species. Attempts to reproduce the hybrid worms or the reciprocal cross were unsuccessful, indicating that hybridization between the two species is a rarely occurring phenomenon.

MINERAL DEFICIENCY IN MULBERRY PLANTS, MORUS ALBA L. AND ITS EFFECT ON ECONOMIC CHARACTERS OF SILK WORM, BOMBYX MORI L

The effect of mineral deficiency on mulberry ntant was studied under pot culture with Kanva-2 mulberry variety under different deficient nutrient conditions. The leaves were chemically analysed and discussed. To test the quality of leaves, a feeding experiment was conducted by feeding the hybrid worm. LX NB,D, from stage upto cocoon formation. The larval, cocoon and silk characters revealed that deficiency in N P and K affected the growth and nutrient content of mulberry leaves which in turn affected the growth and economic characters of silk worm. Among the three elements, p deficiency affected the cocoon characters and silk characters very badly, because deficiency in 'P affected the up- take of other elements in mulberry leaves.

Meiotic abnormalities in backcross lines of hybrid Haemonchus

Le Jambre L. F. and Royal W. M. 1979. Meiotic abnormalities in backcross lines of hybrid Haemonchus. International Journal for Parasitology 10: 281–286. Hybrid worms from the reciprocal matings between Haemonchus contortus and H. placei were backcrossed to the parent species. Six of the possible eight backcrosses produced fertile eggs. The six backcross lines were passaged through sheep for four generations. The adults of this generation had various levels of meiotic abnormality as evidenced by abnormal variations in chromosome structure and aneuploidy. The eggs from backcross lines with a degree of meiotic abnormality had the lowest percentage hatch. Four of the six backcross lines required a higher temperature for larval development than did H. contortus. The size of the third-stage larvae varied from one with larvae larger than H. placei to one line with larvae smaller than H. contortus.