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Colletotrichum gloeosporioides is a species complex of agricultural importance as it causes anthracnose disease on many crop species worldwide, and strong impact regionally on Water Yam (Dioscorea alata) in the Caribbean. In this study, we conducted a genetic analysis of the fungi complex in three islands of the Lesser Antilles—Guadeloupe (Basse Terre, Grande Terre and Marie Galante), Martinique and Barbados. We specifically sampled yam fields and assessed the genetic diversity of strains with four microsatellite markers. We found a very high genetic diversity of all strains on each island, and intermediate to strong levels of genetic structure between islands. Migration rates were quite diverse either within (local dispersal) or between islands (long-distance dispersal), suggesting important roles of vegetation and climate as local barriers, and winds as an important factor in long-distance migration. Three distinct genetic clusters highlighted different species entities, though there was also evidence of frequent intermediates between two clusters, suggesting recurrent recombination between putative species. Together, these results demonstrated asymmetries in gene flow both between islands and clusters, and suggested the need for new approaches to anthracnose disease risk control at a regional level. [ABSTRACT FROM AUTHOR]

Off-road vehicles are potential vectors for the spread of destructive plant pathogens such as Phytophthora cinnamomi. However, the retention of Phytophthora species in soil on vehicles used off-road does not appear to have been assessed empirically. We sampled soil from 22 off-road vehicles used in conservation management in New South Wales and tested samples for the presence of Phytophthora species. Two species (P. cryptogea and P. aff. alticola) were detected from three vehicles. Two of these three vehicles were regarded as being clean externally and had not been used off-road for more than one week. Phytophthora species can therefore survive in small amounts of soil on vehicles for extended periods, potentially facilitating the spread of these destructive pathogens. Cleaning is required of management vehicles entering areas of high conservation value vegetation to minimise the risk of spreading Phytophthora species. However, research is needed to find the most effective methods for removing soil. [ABSTRACT FROM AUTHOR]

El Niño events, the warm phase of the El Niño Southern Oscillation, facilitate the movement of warm surface waters eastwards across the Pacific Ocean. Marine organisms transported by these waters can act as biological corridors for water-borne bacteria with attachment abilities. El Niño events have been hypothesized as driving the recent emergence of Vibrio parahaemolyticus (Vp) variants, marine bacterium causing gastroenteritis, in South America, but the lack of a robust methodological framework limited any further exploration. Here, we introduce two new analysis approaches to explore Vp dynamics in South America, which will be central to uncovering Vp dynamics in the future. Distributed non-linear lag models found that strong El Niño events increase the relative probability of Vp detection in Peru, with a 3-4-month lag time. Machine learning found that the presence of a specific gene ( vopZ ) involved in attachment to plankton in a pandemic Vp clone in South America was temporally associated with strong El Niño events, offering a possible strategy for survival over long-range dispersal, such as that offered by El Niño events. Robust surveillance of marine pathogens and methodological development are necessary to produce resolute conclusions on the effect of El Niño events on water-borne diseases.

A two‐phase Bayesian model is presented for updating risk assessments for locations susceptible to infection by exotic pathogens. Human transportation from previously infected regions to uninfected regions is the main dispersal mechanism. Information embedded in patterns within the transportation flow are exploited in the update process. We explore the sensitivity of the model's outputs to changes in inputs. A sample application of the model to sudden oak death, using fictitious infection data, is performed. [ABSTRACT FROM AUTHOR]

Sexually reproduced, airborne ascospores of Stagonosporopsis citrulli may play a role in its dispersal. S. citrulli causes gummy stem blight (GSB), one of the most important foliar diseases of cucurbits. Four studies were conducted with S. citrulli to investigate for how long ascospores are released and how far they can be dispersed from a source field. In the first study, colonized watermelon debris was sampled during three seasons and samples were assayed for ascospore release. Ascospores were detected 292, 313, and 306 days after inoculation of the source. In the second study, the active release of ascospores from pseudothecia in a Petri dish was monitored for 7 days. The release of ascospores decreased by ≤90% from 1 day after the start of the assay until 7 days after. In the third study, trap plant assays were conducted to measure the dispersal gradient of ascospores up to 366 m from the source. Generally, frequency of pathogen recovery from trap plants decreased with increasing distance from the source. The ascospore dispersal data fitted the exponential model better than the power law model. In the final study, dispersal experiments were conducted under controlled conditions. The incidence of GSB decreased with increasing distance, up to 55 m, from the source. It was concluded that ascospores of S. citrulli can serve as primary inoculum for epidemics and could easily spread among fields. Debris from cucurbit crops can be the source of ascospores for up to 10 months and should be cleared expeditiously. [ABSTRACT FROM AUTHOR]

Fire blight, caused by the bacterial phytopathogen Erwinia amylovora, is an economically important and mechanistically complex disease that affects apple and pear production in most geographic production hubs worldwide. We compile, assess, and present a genetic outlook on the progression of an E. amylovora infection in the host. We discuss the key aspects of type III secretion–mediated infection and systemic movement, biofilm formation in xylem, and pathogen dispersal via ooze droplets, a concentrated suspension of bacteria and exopolysaccharide components. We present an overall outlook on the genetic elements contributing to E. amylovora pathogenesis, including an exploration of the impact of floral microbiomes on E. amylovora colonization, and summarize the current knowledge of host responses to an incursion and how this response stimulates further infection and systemic spread. We hope to facilitate the identification of new, unexplored areas of research in this pathosystem that can help identify evolutionarily susceptible genetic targets to ultimately aid in the design of sustainable strategies for fire blight disease mitigation. [ABSTRACT FROM AUTHOR]

In marine ecosystems, oceanographic processes often govern host contacts with infectious agents. Consequently, many approaches developed to quantify pathogen dispersal in terrestrial ecosystems have limited use in the marine context. Recent applications in marine disease modeling demonstrate that physical oceanographic models coupled with biological models of infectious agents can characterize dispersal networks of pathogens in marine ecosystems. Biophysical modeling has been used over the past two decades to model larval dispersion but has only recently been utilized in marine epidemiology. In this review, we describe how biophysical models function and how they can be used to measure connectivity of infectious agents between sites, test hypotheses regarding pathogen dispersal, and quantify patterns of pathogen spread, focusing on fish and shellfish pathogens. Bio-physical models are a useful tool for understanding dispersal and transmission of marine pathogens. While utilized for larval dispersal models, they are only recently being used in epidemiological studies and are currently underutilized by the marine epidemiology field. Bio-physical models are useful for spatial planning and coastal management. For example, they have been used for spatial planning of salmon farm site locations, and to establish early warning networks. Bio-physical modeling can be used to test hypotheses, rather than simply develop them. Model resolution and computation demands must be balanced when making decisions about model parameters. Epidemiological bio-physical models are in their infancy. While they have proven useful so far, future applications of these models can incorporate more aspects of disease dynamics and address many additional questions. [ABSTRACT FROM AUTHOR]

Understanding the link between microbial community stability and assembly processes is crucial in microbial ecology. Here, we investigated whether the impact of biotic disturbances would depend on the processes controlling community assembly. For that, we performed an experiment using soil microcosms in which microbial communities assembled through different processes were invaded by Escherichia coli. We show that the ecological assembly process of the resident community plays a significant role in invader-resident competition, invader survival, and compositional stability of the resident community. Specifically, the resident communities primarily assembled through stochastic processes were more susceptible to invader survival. Besides, E. coli invasion acts as a biotic selection pressure, leading to competition between the invader and resident taxa, suppressing the stochasticity in the resident community. Taken together, this study provides empirical evidence for the interpretation of microbial community assemblage on their (potential) ecosystem functions and services, such as the prevention of pathogen establishment and the pathogenic states of soil microbiomes., (© The Author(s) 2024. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.)

Two species of microsporidia, Nosema apis and Nosema ceranae, occur regularly and cause significant losses in apiculture throughout the world. N. ceranae is thought to be an emerging pathogen of the European honey bee which is replacing N. apis. Microscopic analysis of honey bees collected in Tyumen region, South-Western Siberia, suggested presence of two microsporidial pathogens slightly differing in spore size and shape. PCR detection using species-specific primer sets 312APIS and 218MITOC followed by PCR product sequencing confirmed the diagnosis of N. apis and N. ceranae, respectively.Microsporidia were present in private apiaries through 2008-2010, and among 21 colonies from 7 localities, two colonies were infected with both pathogens, while infections with N. apis only were detected in 8, and with N. ceranae only in 13 colonies. These data suggest that N. ceranae is widely spread in South-Western Siberia alongside with N. apis and is able to persist in the regions with average January temperatures below -18°C. [ABSTRACT FROM AUTHOR]

Migratory animals are widely assumed to play an important role in the long-distance dispersal of parasites, and are frequently implicated in the global spread of zoonotic pathogens such as avian influenzas in birds and Ebola viruses in bats. However, infection imposes physiological and behavioural constraints on hosts that may act to curtail parasite dispersal via changes to migratory timing ('migratory separation') and survival ('migratory culling')., There remains little consensus regarding the frequency and extent to which migratory separation and migratory culling may operate, despite a growing recognition of the importance of these mechanisms in regulating transmission dynamics in migratory animals., We quantitatively reviewed 85 observations extracted from 41 studies to examine how both infection status and infection intensity are related to changes in body stores, refuelling rates, movement capacity, phenology and survival in migratory hosts across taxa., Overall, host infection status was weakly associated with reduced body stores, delayed migration and lower survival, and more strongly associated with reduced movement. Infection intensity was not associated with changes to host body stores, but was associated with moderate negative effects on movement, phenology and survival., In conclusion, we found evidence for negative effects of infection on host phenology and survival, but the effects were relatively small. This may have implications for the extent to which migratory separation and migratory culling act to limit parasite dispersal in migratory systems. We propose a number of recommendations for future research that will further advance our understanding of how migratory separation and migratory culling may shape host-parasite dynamics along migratory routes globally. [ABSTRACT FROM AUTHOR]

The goal of this study was to develop effective and practical field sampling methods for quantification of aerial deposition of airborne conidia of Entomophaga maimaiga over space and time. This important fungal pathogen is a major cause of larval death in invasive gypsy moth (Lymantria dispar) populations in the United States. Airborne conidia of this pathogen are relatively large (similar in size to pollen), with unusual characteristics, and require specialized methods for collection and quantification. Initially, dry sampling (settling of spores from the air onto a dry surface) was used to confirm the detectability of E. maimaiga at field sites with L. dispar deaths caused by E. maimaiga, using quantitative PCR (qPCR) methods. We then measured the signal degradation of conidial DNA on dry surfaces under field conditions, ultimately rejecting dry sampling as a reliable method due to rapid DNA degradation. We modified a chamber-style trap commonly used in palynology to capture settling spores in buffer. We tested this wet-trapping method in a largescale (137-km) spore-trapping survey across gypsy moth outbreak regions in Pennsylvania undergoing epizootics, in the summer of 2016. Using 4-day collection periods during the period of late instar and pupal development, we detected variable amounts of target DNA settling from the air. The amounts declined over the season and with distance from the nearest defoliated area, indicating airborne spore dispersal from outbreak areas. IMPORTANCE We report on a method for trapping and quantifying airborne spores of Entomophaga maimaiga, an important fungal pathogen affecting gypsy moth (Lymantria dispar) populations. This method can be used to track dispersal of E. maimaiga from epizootic areas and ultimately to provide critical understanding of the spatial dynamics of gypsy moth-pathogen interactions. [ABSTRACT FROM AUTHOR]

Postbloom fruit drop (PFD) is an important citrus disease that causes up to 100% yield losses during years in which conditions are favourable for the occurrence of epidemics. The conidia of Colletotrichum acutatum and C. gloeosporioides, causal agents of PFD, are predominantly dispersed by rain splash. At the beginning of epidemics, the distribution of diseased plants is random and the disease progress rate is very high, which is unusual for pathogens spread by rain splash. As the pathogen produces abundant conidia on diseased petals, pollinating insects may contribute to disease dispersal. This study investigated honeybees (Apis mellifera) as dispersal agents of C. acutatum and C. gloeosporioides among citrus plants. Two experiments were carried out in a screenhouse in which citrus plants were protected (or not) in insect-proof cages. The source of inoculum was placed on one side of the screenhouse, and a honeybee hive was placed on the opposite side. All uncaged plants showed symptoms of the disease, and none of the caged plants exhibited PFD symptoms. The monomolecular model showed a good fit to disease progress in both experiments. Conidiumlike structures of Colletotrichum spp. were identified attached to the bodies of the honeybees by scanning electron microscopy. These results have revealed that honeybees disperse Colletotrichum among citrus plants. [ABSTRACT FROM AUTHOR]

Quantitatively mapping the spatial distributions of infectious diseases is key to both investigating their epidemiology and identifying populations at risk of infection. Important advances in data quality and methodologies have allowed for better investigation of disease risk and its association with environmental factors. However, incorporating dynamic human behavioural processes in disease mapping remains challenging. For example, connectivity among human populations, a key driver of pathogen dispersal, has increased sharply over the past century, along with the availability of data derived from mobile phones and other dynamic data sources. Future work must be targeted towards the rapid updating and dissemination of appropriately designed disease maps to guide the public health community in reducing the global burden of infectious disease. [ABSTRACT FROM AUTHOR]

Avian influenza viruses (AIVs) are of great concern worldwide due to their economic impact and the threat they represent to human health. As wild birds are the natural reservoirs of AIVs, understanding AIV dynamics in different avian taxa is essential for deciphering the epidemiological links between wildlife, poultry and humans. To date, only the Anatidae (ducks, geese and swans) have been widely studied. Here, we aim to shed light on the current state of knowledge on AIVs in Laridae (gulls, terns and kittiwakes) versus that in Anatidae by setting forth four fundamental questions: how, when, where and to which host species are AIVs transmitted? First, we describe ecological differences between Laridae and Anatidae and discuss how they may explain observed contrasts in preferential transmission routes and the evolution of specific AIV subtypes. Second, we highlight the dissimilarities in the temporal patterns of AIV shedding between Laridae and Anatidae and address the role that immunity likely plays in shaping these patterns. Third, we underscore that Laridae may be key in promoting intercontinental exchanges of AIVs. Finally, we emphasize the crucial epidemiological position that Laridae occupy between wildlife, domestic birds and humans. [ABSTRACT FROM AUTHOR]

Clubroot of canola was identified for the first time on the Canadian prairies in 2003, and is spreading rapidly across the region. Although clubroot has been studied extensively on vegetable Brassica crops, it was not clear initially how much of the information would be directly transferable from the intensive production of vegetable crops to the extensive production practices used for canola. This review examines similarities and differences between clubroot development and management on vegetable crops and canola. One important difference was that clubroot generally has a larger economic impact on canola, which is harvested for seed, than on vegetables, especially those where early vegetative growth is the marketable component. Also, clubroot has spread within the production area more quickly than was expected based on vegetable production. This occurs in large part because the resting spores are readily moved within and between fields on the heavy machinery used for canola production, but movement of spores by wind and water is also being assessed. Interestingly, crop rotation to reduce yield losses may be a more viable approach for canola than in vegetable production. Resistance to clubroot is the most consistent and economically viable approach to clubroot management in canola, but several lines of evidence indicate that this resistance may not be durable. Fortunately, the large acreage of canola production in Canada ensures that new sources of resistance will be developed and deployed as existing sources are eroded. Pathogen development and cultural control are very similar on vegetables and canola; bait crops and soil amendments are generally not commercially viable in either system; and biocontrol has a limited potential at this time. Manipulation of seeding date, application of fungicide, and soil fumigation generally have more potential for use in vegetable production than for canola. Identification of approaches that reduce disease pressure in clubroot-infested fields and increase the durability and diversity of genes for clubroot resistance represent important lines of future research. [ABSTRACT FROM AUTHOR]

Citrus canker ( Xanthomonas citri subsp. citri (Xcc)) can cause yield loss and trade restrictions. The pathogen is dispersed in rain splash and spread is promoted by wind. The goal of this study was to gain some insight into the properties of short-distance splash dispersal of Xcc from ∼1·5 m-tall cankered grapefruit canopies in turbulent wind, common during rainstorms in Florida. Turbulent wind up to 19·9 m s−1 was tested in five experiments. Bacteria flux density (BFD, bacteria cm−2 min−1) was quantified at heights of 30, 70, 110, 130 and 180 cm above ground, and at four horizontal points (17, 51, 85 and 119 cm) at each height across the direction of the wind 1 m downwind. BFD varied among experiments, but the lowest BFDs were consistently detected at the greatest sample height. Despite differences between experiments, the relationship between log BFD and sample height was consistently described by a linear function ( P = 0·06-<0·0001, R2 = 0·75->0·99). The BFD collected at the horizontal points across the wind path was variable. BFDs collected were sometimes significantly different, but no relationship was discernible. Stronger, turbulent wind resulted in greater BFD, with a linear function describing the relationship between log BFD and wind speed ( P = 0·2-0·02, R2 = 0·94-0·96). Multiple regression analysis demonstrated predictability of the proportion of total bacteria collected ( F = 141, P < 0·0001, d.f. = 3, R2 = 0·53). [ABSTRACT FROM AUTHOR]

Abstract: Biological invasions represent a major threat to the function and composition of ecosystems. Although the degree of invasion success of a non-native species and the consequent damage it causes can vary among and within invading species, the absence or presence of natural enemies associated with the invader can also play roles in the invasion dynamics. We used newly established, spatially isolated populations of the gypsy moth, Lymantria dispar (L.), on some of the islands within the archipelago of the Apostle Islands National Lakeshore in northwestern Wisconsin, USA, to study the establishment and initial spread of two releases of the entomophthoralean fungus Entomophaga maimaiga. We also explored patterns in rates of infection by the L. dispar nucleopolyhedrovirus, which was also released on three islands, and in the rates of parasitism by generalist parasitoids. The mean initial rate of spread by E. maimaiga following its successful establishment was 0.8kmyear−1, although it was detected as far as 6.1km from a release site after one year. Infection rates by both entomopathogens were highest on those islands where they were released; however, rates of parasitism by larval parasitoids were highest where neither pathogen had been released, suggesting that pathogens outcompete larval parasitoids. Understanding the intricate relationship between an invading host species and their associated pathogens during the early stages of invasion could enhance the use of biological control in invasive species management. [Copyright &y& Elsevier]

Basidiospores are implicated in the distribution and genetic diversity of Ganoderma boninense, cause of basal stem rot (BSR) and upper stem rot (USR) of oil palm ( Elaeis guineensis). Measurement of aerial basidiospores within plantations in Sumatra showed continuous and high production over 24 h (range c. 2-11 000 spores m−3) with maximum release during early evening. Basidiospores applied to cut surfaces of fronds, peduncles and stems germinated in situ. Equivalent, extensive wounds are created during plantation harvesting and management and represent potential sites for formation of infective heterokaryons following mating of haploid basidiospore germlings. Use of spore-sized micro-beads showed that basidiospores could be pulled up to 10 cm into severed xylem vessels, where they are relatively protected from dehydration, UV irradiation and competing microflora. Diversity of isolates from five locations on two plantations was assessed by RAMS fingerprinting. Isolates from within individual palms with USR were identical and represent single infections, but different USR infections had unique band patterns and revealed separate infections. Some BSR-affected trees contained more than one isolate, and thus had multiple infections. There was one example of adjacent BSR palms with the same isolate, indicating vegetative spread, but there were no identical genets from BSR infections and adjacent fallen palms. Isolate diversity was as great within a plantation as between plantations. It is evident that basidiospores play a major role in spread and genetic variability of G. boninense. Evidence for direct basidiospore infection via cut fronds, indirectly through roots via colonized debris and less frequently, infection by vegetative, clonal spread is considered. [ABSTRACT FROM AUTHOR]

The role of pollen in disseminating Pseudomonas syringae pv. actinidiae (Psa ) in kiwifruit orchards was investigated and the survival of the pathogen as an epiphyte on leaves and fruits was followed, from pollination time until the preharvest season. Pollen with natural inoculum was obtained from an infected orchard and pollen harvested without any contamination by Psa was experimentally inoculated at approximately the same contamination level. Two pollination techniques were used in glasshouse experiments: dusting and spraying. In parallel, field trials in commercial orchards were carried out: two plots were designed in two orchards, where bacterial canker was present at low incidence. From petal fall to 3 weeks before harvesting, leaf and fruit samples were taken and analysed for the presence of Psa, using two different PCR protocols and direct isolation. Results confirmed the dissemination of Psa through pollen, especially when using the aqueous suspensions. Both in glasshouse experiments and in the orchards Psa was found as an epiphyte for several weeks after pollination. Pathogen populations on leaves were, initially, 10 to 100 times less than on fruitlets. As the summer continued, the epiphytic contamination levels of fruits decreased constantly, being no more detectable from early August, whereas Psa was present at detectable levels on leaves until early October, approx. 20 days before harvesting time. Our results confirmed the role of pollen in disseminating Psa, the long epiphytic survival of the pathogen on kiwifruit leaves and the increasing unsuitability of fruits to harbour detectable, epiphytic populations of the bacterium through the summer season in commercial orchards with low disease incidence, when they are reaching the final development stage. Thus, kiwifruit surfaces do not appear to be a suitable niche for a long term survival of Psa as an epiphyte and, therefore, kiwifruits should not represent a pathway for Psa dissemination and pose a negligible risk for the introduction of the pathogen into new areas. [ABSTRACT FROM AUTHOR]

Using a model plant-pathogen system in a large-scale habitat corridor experiment, we found that corridors do not facilitate the movement of wind-dispersed plant pathogens, that connectivity of patches does not enhance levels of foliar fungal plant disease, and that edge effects are the key drivers of plant disease dynamics. Increased spread of infectious disease is often cited as a potential negative effect of habitat corridors used in conservation, but the impacts of corridors on pathogen movement have never been tested empirically. Using sweet corn (Zea mays) and southern corn leaf blight (Cochliobolus heterostrophus) as a model plant-pathogen system, we tested the impacts of connectivity and habitat fragmentation on pathogen movement and disease development at the Savannah River Site, South Carolina, USA. Over time, less edgy patches had higher proportions of diseased plants, and distance of host plants to habitat edges was the greatest determinant of disease development. Variation in average daytime temperatures provided a possible mechanism for these disease patterns. Our results show that worries over the potentially harmful effects of conservation corridors on disease dynamics are misplaced, and that, in a conservation context, many diseases can be better managed by mitigating edge effects. [ABSTRACT FROM AUTHOR]

Abstract: Conventional agriculture uses herbicides, pesticides, and chemical fertilizers that have the potential to pollute the surrounding land, air and water. Organic agriculture tries to avoid using these and promotes an environmentally friendly approach to agriculture. Instead of relying on herbicides, pesticides and chemical fertilizers, organic agriculture promotes a whole system approach to managing weeds, pests and nutrients, while regulating permitted amendments. In this paper, we consider the effect of increasing the total area of agricultural land under organic practices, against a background of conventional agriculture. We hypothesized that at a regional scale, organic agriculture plots benefit from existing in a background of conventional agriculture, that maintains low levels of pathogens through pesticide applications. We model pathogen dispersal with a diffusive logistic equation in which the growth/death rate is spatially heterogeneous. We find that if the ratio of the organic plots to conventional plots remains below a certain threshold l c , the pest population is kept small. Above this threshold, the pest population in the organic plots grows rapidly. In this case, the area in organic agriculture will act as a source of pest to the surrounding region, and will always infect organic plots as they become more closely spaced. Repeated localized epidemics of pest outbreaks threaten global food security by reducing crop yields and increasing price volatility. We recommend that regional estimates of this threshold are necessary to manage the growth of organic agriculture region by region. [Copyright &y& Elsevier]

The movement of faecal pathogens from land to surface and ground-water are of great interest because of the public and livestock health implications. Knowledge of canopy structure and how it might be managed to help mitigate nutrient and pathogen movement in pasture is needed to create management practices that balance livestock production with environmental benefits. An experiment was conducted using a rainfall-simulating device to test whether canopy structure of species common to pastures in Appalachia, USA could be managed to influence dispersion of faecal pathogens. Seven pots (30-cm diameter) of white clover, orchardgrass and perennial ryegrass were lined up on horizontal and sloping surfaces under a rainfall simulator. The centre pot was inoculated at the soil surface with 4 × 1010 faecal coliform bacteria (FC) just before rainfall simulation started. The species were maintained under short, moderate and tall canopy management treatments. White clover exhibited the greatest rates of lateral and vertical dispersion of FC into the canopy, especially in the short canopy management treatment following 30 min of rainfall (about 40 mm). Low concentrations of faecal coliform bacteria also dispersed into the canopies of the grass species but the differences in concentration of FC between the grass species were not different. When the proportion of white clover in a pasture is high, the canopy should be relatively taller to reduce the likelihood of infection associated with faecal coliform-contaminated herbage. [ABSTRACT FROM AUTHOR]

Abstract: The movement of fecal pathogens from land to surface and ground water are of great interest because of the public health implications. Non-structural best management practices that control the timing, volume, and placement of animal manures are commonly used to limit opportunities for fecal pathogens to enter water bodies. Increased infiltration capacity, water and waste diversions, and vegetated filter strips are used to control fecal pathogen movement in surface runoff. Fecal pathogens transported by rain splash could conceivably bypass physical barriers. The relationship between slope angle and the transport of fecal coliform bacteria by rain splash was studied. It was hypothesized that there would be a significant down slope transport of fecal coliform bacteria by raindrops falling on a bare soil surface inoculated with fecal coliform bacteria. Slopes from 0° to 40.8° were studied. The mean splash distance for fecal coliforms was less than 50mm in all directions at 0° slope and more than 500mm in the downslope direction on a 40.8° slope. Maximum splash distances ranged from about 400mm on the horizontal surface to more than 1900mm in the downslope direction on the 40.8° slope. Sequential downhill movement of fecal coliform (FC) bacteria by repeated rain splash could transport FC directly to water bodies or areas of saturation excess where they will become entrained in overland runoff. Further studies on raindrop and rainfall characteristics, as well as surface cover and soil characteristics, will be necessary to more fully understand the mechanisms of FC transport on sloping land by rain splash. [Copyright &y& Elsevier]

Abstract: We examined the potential of the dimensionless Weber number of an impacting water drop for predicting the associated gradient of pathogen dispersal. Previously shown to be related to the mechanisms of splash droplet formation, the Weber number compares the inertial forces to surface tension force of the drop. Based on new data on tomato late blight and previously published data on wheat rust diseases and on strawberry diseases, the number of spores splashed by incident drops at a given distance from the source is expressed as a negative exponential function of distance multiplied by the pathogen deposition term in the immediate vicinity of the source. Results show strong evidence that the pathogen deposition term is well described by a power law function of the Weber number. [Copyright &y& Elsevier]

A general model of insect-pathogen dynamics is presented which includes explicit host and pathogen dispersal. Four distinctive, wave-like, patterns of dispersal are produced which can be categorised by two universal parameters – the speed of advance, and the position of the leading edge, of the wave of dispersal of the host relative to that of the disease. These patterns are (1) the pathogen becomes extinct, allowing the host to disperse at the carrying capacity across the land surface, (2) the host disperses more rapidly than the pathogen, producing host densities at the carrying capacity in a region behind the leading edge of the wave, with these densities reduced due to interaction with the pathogen in the wave interior, (3) the host and pathogen disperse at the same speed but the leading edge of the host extends beyond that of the pathogen, allowing the host to reach ‘high’ density at the leading edge only, and (4) the host and pathogen disperse at the same speed but the leading edge of the pathogen extends beyond that of the host, producing ‘low’ density host dispersal across the land surface. A biological description explaining the causes of these patterns has important consequences regarding the use of pathogens for biological control of insect pests. The model is modified to represent a specific insect-pathogen system, the winter moth, Operophtera brumata , and its nuclear polyhedrosis virus. The same patterns, categorised by the same universal parameters, are observed. Thus, it is suggested that the strength of infection and the relative dispersal rates of the host and pathogen are influential in determining the patterns of host outbreaks observed in this insect. [ABSTRACT FROM AUTHOR]

This section introduces a series of articles about ancient granulomas including an update on research in granulomatous infectious/diseases, overview of the M.tb granuloma research and the host-pathogen interaction, and a review of the helminth-induced granulomatous schistosomiasis mansoni.