Infection Rates In Populations Research Articles

Population genetic structure of Culex tritaeniorhynchus in different types of climatic zones in China

BackgroundCulex tritaeniorhynchus is widely distributed in China, from Hainan Island in the south to Heilongjiang in the north, covering tropical, subtropical, and temperate climate zones. Culex tritaeniorhynchus carries 19 types of arboviruses. It is the main vector of the Japanese encephalitis virus (JEV), posing a serious threat to human health. Understanding the effects of environmental factors on Culex tritaeniorhynchus can provide important insights into its population structure or isolation patterns, which is currently unclear.ResultsIn total, 138 COI haplotypes were detected in the 552 amplified sequences, and the haplotype diversity (Hd) value increased from temperate (0.534) to tropical (0.979) regions. The haplotype phylogeny analysis revealed that the haplotypes were divided into two high-support evolutionary branches. Temperate populations were predominantly distributed in evolutionary branch II, showing some genetic isolation from tropical/subtropical populations and less gene flow between groups. The neutral test results of HNQH (Qionghai) and HNHK(Haikou) populations were negative (P < 0.05), indicating many low-frequency mutations in the populations and that the populations might be in the process of expansion. Moreover, Wolbachia infection was detected only in SDJN (Jining) (2.24%), and all Wolbachia genotypes belonged to supergroup B. To understand the influence of environmental factors on mosquito-borne viruses, we examined the prevalence of Culex tritaeniorhynchus infection in three ecological environments in Shandong Province. We discovered that the incidence of JEV infection was notably greater in Culex tritaeniorhynchus from lotus ponds compared to those from irrigation canal regions. In this study, the overall JEV infection rate was 15.27 per 1000, suggesting the current risk of Japanese encephalitis outbreaks in Shandong Province.ConclusionsTropical and subtropical populations of Culex tritaeniorhynchus showed higher genetic diversity and those climatic conditions provide great advantages for the establishment and expansion of Culex tritaeniorhynchus. There are differences in JEV infection rates in wild populations of Culex tritaeniorhynchus under different ecological conditions. Our results suggest a complex interplay of genetic differentiation, population structure, and environmental factors in shaping the dynamics of Culex tritaeniorhynchus. The low prevalence of Wolbachia in wild populations may reflect the recent presence of Wolbachia invasion in Culex tritaeniorhynchus.

Salinity and temperature affect the symbiont profile and host condition of Florida USA blue crabs Callinectes sapidus

Subtropical Florida blue crabs, Callinectes sapidus, exhibit differing life history traits compared to their temperate counterparts, likely influencing symbiont infection dynamics. Little information exists for Florida C. sapidus symbiont profiles, their distribution among various habitats, and influence on crab condition. Using histopathology, genomics, and transmission electron microscopy, we describe the first symbiont profiles for Florida C. sapidus occupying freshwater to marine habitats. Twelve symbiont groups were identified from 409 crabs including ciliophorans, digenean, microsporidian, Haplosporidia, Hematodinium sp., Nematoda, filamentous bacteria, gregarine, Callinectes sapidus nudivirus, Octolasmis sp., Cambarincola sp., and putative microcell. Overall, 78% of C. sapidus were documented with one or more symbiont groups demonstrating high infection rates in wild populations. Environmental variables water temperature and salinity explained 48% of the variation in symbiont groups among Florida habitats, and salinity was positively correlated with C. sapidus symbiont diversity. This suggests freshwater C. sapidus possess fewer symbionts and represent healthier individuals compared to saltwater populations. Crab condition was examined using the reflex action mortality predictor (RAMP) to determine if reflex impairment could be linked to symbiont prevalence. Symbionts were found positively correlated with crab condition, and impaired crabs were more likely to host symbionts, demonstrating symbiont inclusion may boost predictive ability of the RAMP application. The microsporidian symbiont group had a particularly strong effect on C. sapidus reflex response, and impairment was on average 1.57 times higher compared to all other symbiont groups. Our findings demonstrate the importance of considering full symbiont profiles and their associations with a spatially and temporally variable environment to fully assess C. sapidus population health.

Analysis of trapped mosquito excreta as a noninvasive method to reveal biodiversity and arbovirus circulation.

Emerging and endemic mosquito-borne viruses can be difficult to detect and monitor because they often cause asymptomatic infections in human or vertebrate animals or cause nonspecific febrile illness with a short recovery waiting period. Some of these pathogens circulate into complex cryptic cycles involving several animal species as reservoir or amplifying hosts. Detection of cases in vertebrate hosts can be complemented by entomological surveillance, but this method is not adapted to low infection rates in mosquito populations that typically occur in low or nonendemic areas. We identified West Nile virus circulation in Camargue, a wetland area in South of France, using a cost-effective xenomonitoring method based on the molecular detection of virus in excreta from trapped mosquitoes. We also succeeded at identifying the mosquito species community on several sampling sites, together with the vertebrate hosts on which they fed prior to being captured using amplicon-based metabarcoding on mosquito excreta without processing any mosquitoes. Mosquito excreta-based virus surveillance can complement standard surveillance methods because it is cost-effective and does not require personnel with a strong background in entomology. This strategy can also be used to noninvasively explore the ecological network underlying arbovirus circulation.

Influence of delayed density and ultraviolet radiation on caterpillar baculovirus infection and mortality.

Infectious disease is an important potential driver of population cycles but must occur through delayed density-dependent infection and resulting fitness effects. Delayed density-dependent infection by baculoviruses can be caused by environmental persistence of viral occlusion bodies (OBs), which can be influenced by environmental factors. Specifically, ultraviolet radiation is potentially important in reducing the environmental persistence of viruses by inactivating OBs. Delayed density-dependent viral infection has rarely been observed empirically at the population level although theory predicts that it is necessary for pathogens to drive population cycles. Similarly, field studies have not examined the effects of ultraviolet radiation on viral infection rates in natural animal populations. We tested if viral infection is delayed density-dependent with the potential to drive cyclic dynamics and if ultraviolet radiation influences viral infection levels. We censused 18 Ranchman's tiger moth (Arctia virginalis) populations across 9° of latitude over 2 years and quantified the effects of direct and delayed density and ultraviolet radiation on proportion infected by baculovirus, infection severity and survival to adulthood. Caterpillars were collected from field populations and reared in the laboratory. Baculovirus has not previously been described infecting A. virginalis, and we used genetic methods to confirm the identity of the virus. We found that proportion infected, infection severity and survival to adulthood exhibited delayed density dependence. Ultraviolet radiation in the previous summer decreased infection severity, which increased caterpillar survival probability. Structural equation modelling indicated that the effect of lagged density on caterpillar survival was mediated through proportion infected and infection severity and was 2.5-fold stronger than the indirect effect of ultraviolet. We successfully amplified polh, lef-8 and lef-9 viral genes from caterpillars, and BLAST results confirmed that the virus was a nucleopolyhedrovirus. Our findings provide clear evidence that delayed density-dependent mortality can arise through viral infection rate and severity in insects, which supports the role of viral disease as a mechanism, among others, that may drive insect population cycles. Furthermore, our findings support predictions that ultraviolet radiation can modify viral disease dynamics in insect populations, most likely through attenuating viral persistence in the environment.

Angiostrongylus vasorum, Aelurostrongylus abstrusus, Crenosoma vulpis and Troglostrongylus brevior Infections in Native Slug Populations of Bavaria and Baden-Wuerttemberg in Germany.

Angiostrongylus vasorum, Crenosoma vulpis, Aelurostrongylus abstrusus and Troglostrongylus brevior can cause severe cardiovascular and pulmonary symptoms in companion animals and wildlife. Recently, these nematodes were reported to spread within Europe and South America. The reasons behind this are still unknown, but obligate gastropod intermediate host populations might play a role. Therefore, lungworm infections in terrestrial slug populations in selected geographic areas of the Federal States of Bavaria and of Baden-Wuerttemberg, Germany, were studied. In total, 517 slugs (462 Arion spp., 51 Deroceras reticulatum, one Limax maximus, and three unknown slug species) were collected in the summer and autumn seasons, artificially digested and microscopically and molecularly analyzed for the presence of metastrongyloid lungworm larvae. Overall, gastropods showed a prevalence of 11.61% (60/517) for A. vasorum, 1.74% (9/517) for A. abstrusus, 0.77% (4/517) for C. vulpis and 0.97% (5/517) for T. brevior infections, respectively. In Obrigheim (Baden-Wuerttemberg), a hyperendemic focus of canine angiostrongylosis was identified. Here, gastropod infection rates rose from 13.60% (17/125) to 62.96% (34/54) within a few months. In total, 25.61% (84/328) of analysed terrestrial gastropods from Baden-Wuerttemberg were positive for metastrongyloids. In contrast, Bavarian gastropods showed a much lower prevalence of 4.76% (9/189). For the first time, the presence of T. brevior was confirmed for Arion spp. in Baden-Wuerttemberg via molecular analyses. Overall, the current data confirm that canine angiostrongylosis occurs in hyperendemic foci in certain geographic areas with high infection rates in intermediate host populations. As a result, the prevalence for a specific region can rise remarkably within a short period of time. Thus, for a better understanding of lungworm epidemiology in Germany and to protect dogs from angiostrongylosis in hyperendemic foci, it seems mandatory to enhance current efforts on Metastrongyloidea-targeted monitoring on a geographical and time span-related level.

343. RURAL-COVID-19 Trial: Retrospective Analysis of COVID-19 Coinfections in Hospitalized Urban and Rural Adults

BackgroundThe impact of COVID-19 in rural communities has been well described. However, little is known regarding differences in coinfections among COVID-19 patients in rural vs. urban settings. Our primary objective is to evaluate community acquired coinfection (CACo) rates (< 72 hrs from admission) and healthcare-associated infection (HAI) rates ( > 72 hrs from admission) in these populations. Secondary objectives include use of empiric antibiotics, pathogen prevalence, and patient outcomes. MethodsRetrospective analysis of the first 255 adult patients admitted to a tertiary medical center with symptomatic COVID-19 and confirmed by PCR. Rural and urban categories were determined using patient address and county census data. Isolated pathogens were individually evaluated and considered coinfections if the patient met predetermined criteria. Predetermined Coinfection Criteria ResultsThe rates of CACo for rural (n = 90) and urban (n = 165) residents were 11.1% and 13.3%, respectively. Non-respiratory coinfections, such as bloodstream and urinary tract infections, were more common in urban residents; however, empiric antibiotics were started in 75.1% of all subjects. Methicillin susceptible staphylococcus aureus and Escherichia coli were the most common pathogens isolated on admission in both populations. HAI rates were 13.3% in the rural residents vs 13.9% in the urban residents with Methicillin resistant staphylococcus aureus as the most common respiratory pathogen, although Pseudomonas aeruginosa was the most prevalent overall pathogen. There was no significant difference in hospital length of stay or 30-day all-cause mortality among both populations. Patient Outcomes Among Rural and Urban Populations ConclusionThere was no significant difference in the rate of CACo or HAI among rural or urban populations. Despite the high rate of antibiotic use to empirically cover community acquired respiratory infections at the start of the pandemic, only 1.9% of the subjects had a possible or proven respiratory coinfection on admission. Despite prior research showing worse outcomes for rural populations with COVID-19, our data demonstrates that coinfection rates and patient outcomes were similar among these populations when receiving medical care at an academic hospital. Disclosures All Authors: No reported disclosures

Antibody conversion rates to SARS-CoV-2 in saliva from children attending summer schools in Barcelona, Spain

BackgroundSurveillance tools to estimate viral transmission dynamics in young populations are essential to guide recommendations for school opening and management during viral epidemics. Ideally, sensitive techniques are required to detect low viral load exposures among asymptomatic children. We aimed to estimate SARS-CoV-2 infection rates in children and adult populations in a school-like environment during the initial COVID-19 pandemic waves using an antibody-based field-deployable and non-invasive approach.MethodsSaliva antibody conversion defined as ≥ 4-fold increase in IgM, IgA, and/or IgG levels to five SARS-CoV-2 antigens including spike and nucleocapsid constructs was evaluated in 1509 children and 396 adults by high-throughput Luminex assays in samples collected weekly in 22 summer schools and 2 pre-schools in 27 venues in Barcelona, Spain, from June 29th to July 31st, 2020.ResultsSaliva antibody conversion between two visits over a 5-week period was 3.22% (49/1518) or 2.36% if accounting for potentially cross-reactive antibodies, six times higher than the cumulative infection rate (0.53%) assessed by weekly saliva RT-PCR screening. IgG conversion was higher in adults (2.94%, 11/374) than children (1.31%, 15/1144) (p=0.035), IgG and IgA levels moderately increased with age, and antibodies were higher in females. Most antibody converters increased both IgG and IgA antibodies but some augmented either IgG or IgA, with a faster decay over time for IgA than IgG. Nucleocapsid rather than spike was the main antigen target. Anti-spike antibodies were significantly higher in individuals not reporting symptoms than symptomatic individuals, suggesting a protective role against COVID-19.ConclusionSaliva antibody profiling including three isotypes and multiplexing antigens is a useful and user-friendlier tool for screening pediatric populations to detect low viral load exposures among children, particularly while they are not vaccinated and vulnerable to highly contagious variants, and to recommend public health policies during pandemics.

Infection rate models for COVID-19: Model risk and public health news sentiment exposure adjustments.

During the COVID-19 pandemic, governments globally had to impose severe contact restriction measures and social mobility limitations in order to limit the exposure of the population to COVID-19. These public health policy decisions were informed by statistical models for infection rates in national populations. In this work, we are interested in modelling the temporal evolution of national-level infection counts for the United Kingdom (UK-Wales, England, Scotland), Germany (GM), Italy (IT), Spain (SP), Japan (JP), Australia (AU) and the United States (US). We model the national-level infection counts for the period January 2020 to January 2021, thus covering both the pre- and post-vaccine roll-out periods, in order to better understand the most reliable model structure for the COVID-19 epidemic growth curve. We achieve this by exploring a variety of stochastic population growth models and comparing their calibration, with respect to in-sample fitting and out-of-sample forecasting, both with and without exposure adjustment, to the most widely used and reported growth model, the Gompertz population model, often referred to in the public health policy discourse during the COVID-19 pandemic. Model risk as we explore it in this work manifests in the inability to adequately capture the behaviour of the disease progression growth rate curve. Therefore, our concept of model risk is formed relative to the standard reference Gompertz model used by decision-makers, and then we can characterise model risk mathematically as having two components: the dispersion of the observation distribution, and the structure of the intensity function over time for cumulative counts of new infections daily (i.e. the force of infection) attributed directly to the COVID-19 pandemic. We also explore how to incorporate in these population models the effect that governmental interventions have had on the number of infected cases. This is achieved through the development of an exposure adjustment to the force of infection comprised of a purpose-built sentiment index, which we construct from various authoritative public health news reporting. The news reporting media we employed were the New York Times, the Guardian, the Telegraph, Reuters global blog, as well as national and international health authorities: the European Centre for Disease Prevention and Control, the United Nations Economic Commission for Europe, the United States Centres for Disease Control and Prevention, and the World Health Organisation. We find that exposure adjustments that incorporate sentiment are better able to calibrate to early stages of infection spread in all countries under study.

Borrelia burgdorferi Sensu Lato in Questing and Engorged Ticks from Different Habitat Types in Southern Germany.

Borrelia burgdorferi sensu lato (s.l.) causes the most common tick-borne infection in Europe, with Germany being amongst the countries with the highest incidences in humans. This study aimed at (1) comparing infection rates of B. burgdorferi s.l. in questing Ixodes ricinus ticks from different habitat types in Southern Germany, (2) analysing genospecies distribution by habitat type, and (3) testing tissue and ticks from hosts for B. burgdorferi s.l. Questing ticks from urban, pasture, and natural habitats together with feeding ticks from cattle (pasture) and ticks and tissue samples from wild boars and roe deer (natural site) were tested by PCR and RFLP for species differentiation. B. burgdorferi s.l. was found in 29.8% questing adults and 15% nymphs. Prevalence was lower at the urban sites with occurrence of roe deer than where these were absent. Borrelia burgdorferi s.l. DNA was found in 4.8% ticks from roe deer, 6.3% from wild boar, and 7.8% from cattle. Six genospecies were identified in unfed ticks: Borrelia afzelii (48.6%), Borrelia burgdorferi sensu stricto (16%), Borrelia garinii (13.2%), Borrelia valaisiana (7.5%), Borrelia spielmanii (6.2%), and Borrelia bavariensis (0.9%). This study shows high infection levels and a great diversity of Borrelia in questing ticks. The presence of roe deer seems to reduce B. burgdorferi s.l. infection rates in tick populations.

Using Loops to Jump Through Hoops in Flaviviridae

Recent advances in diagnostic testing measures are crucial in determining infection rates in large populations. For Deer Tick Virus (DTV), a member of Flaviviridae, there has been minimal amounts of testing since its prevalence in recent decades. Here we examine recently developed loop-mediated isothermal amplification (LAMP) primers that target the RNA-dependent RNA-polymerase at the terminal end of the polycistron. This sequence is highly conserved across the genus and can provide addition diagnostic potential when considering testing where multiple viruses are endemic to a region. The benefits of using LAMP are increasingly useful in the diagnostic setting where rapid results are needed, and low-cost care is required without use of a thermocycler. We also investigate the possibility of a new type of multiplex LAMP assay that could advance upon our current findings of sequence homology within the viral family. We intend to report upon the progress to implement this technology as a bioinformatics program that can be utilized for further multiplex LAMP testing in vitro.

Efficacy of intravenous immunoglobulins in the prophylaxis of neonatal sepsis

Despite critical care advances, robust antibiotic therapy and improved strategies in early detection and prevention of infection, the incidence of morbidity and mortality from neonatal sepsis worldwide in preterm and low birth weight neonates remains overwhelmingly high. Neonatal sepsis is characterised by a clinical syndrome of systemic signs of infection and bloodstream bacteraemia in newborns within the first months of life. The risk of sepsis in neonates is inversely proportional to gestational age and birth weight due to deficiency in humoral immunity and the need for more invasive supportive neonatal intensive care unit interventions. Adverse effects such as necrotising enterocolitis associated with antimicrobial therapy are serious enough to warrant exploration of alternative therapeutic strategies. Immunoglobulin replacement therapy offers hope of enhancing immune competence and reducing infection rates in vulnerable populations. It is evident from the relevant studies to date that the benefits offered by intravenous immunoglobulin prophylaxis may not be significant enough for routine hospital implementation. Further research to better understand the mechanisms underlying immunodeficiency will lead to the realisation of alternative therapeutic and prophylactic interventions.

Infection Rate Models for COVID-19: Model Risk and Public Health News Sentiment Exposure Adjustments.

During the COVID-19 pandemic, governments globally had to impose severe contact restriction measures and social mobility limitations in order to limit the exposure of the population to COVID-19. These public health policy decisions were informed by statistical models for infection rates in national populations. In this work we are interested in modelling the temporal evolution of national level infection counts for a variety of countries, in order to better understand the most reliable model structure for the COVID-19 epidemic growth curve. We will achieve this by exploring a variety of stochastic population growth models and comparing their calibration to the most widely used and reported growth model, the Gompertz population model, often referred to in the public health policy discourse during the COVID-19 pandemic. Model risk as we explore it in this work manifests in the inability to adequately capture the behaviour of the disease progression growth rate curve. Therefore, our concept of model risk is formed relative to the standard reference used by decision makers, the Gompertz model, and then we can characterize model risk mathematically as having two components: the dispersion of the observation distribution, and the structure of the intensity function over time for cumulative counts of new infections daily (i.e. the force of infection) attributed directly to the COVID-19 pandemic. We also explore how to incorporate in these population models the effect that governmental interventions have had on the number of infected cases. This is achieved through development of an exposure adjustment to the force of infection comprised of a purpose built sentiment index constructed from a variety of authoritative public health reporting. We find that exposure adjustments that incorporate sentiment are better able to calibrate to early stages of infection spread in all countries under study.

Tick populations from endemic and non-endemic areas in Germany show differential susceptibility to TBEV

Tick-borne encephalitis virus (TBEV) is endemic in twenty-seven European countries, transmitted via the bite of an infected tick. TBEV is the causative agent of one of the most important viral diseases of the central nervous system (CNS). In Germany, 890 human cases were registered between the years 2018–2019. The castor bean tick, Ixodes ricinus, is the TBEV vector with the highest importance in Central Europe, including Germany. Despite the nationwide distribution of this tick species, risk areas of TBEV are largely located in Southern Germany. To increase our understanding of TBEV-tick interactions, we collected ticks from different areas within Germany (Haselmühl/Bavaria, Hanover/Lower Saxony) and infected them via an in vitro feeding system. A TBEV isolate was obtained from an endemic focus in Haselmühl. In two experimental series conducted in 2018 and 2019, ticks sampled in Haselmühl (TBEV focus) showed higher artificial feeding rates, as well as higher TBEV infections rates than ticks from the non-endemic area (Hanover). Other than the tick origin, year and month of the infection experiment as well as co-infection with Borrelia spp., had a significant impact on TBEV Haselmühl infection rates. Taken together, these findings suggest that a specific adaptation of the tick populations to their respective TBEV virus isolates or vice versa, leads to higher TBEV infection rates in those ticks. Furthermore, co-infection with other tick-borne pathogens such as Borrelia spp. can lower TBEV infection rates in specific populations.

A situation analysis of the state of supply of in vitro diagnostics in Low-Income Countries

ABSTRACT In vitro diagnostics (IVDs) are medical devices and accessories used to test bodily samples for causative agents of disease. IVDs play a central role in the diagnosis of individuals, in the rationale use of medicines, in burden of disease estimates, as well as in public health surveillance; especially for detection of emerging epidemics, the identification and monitoring of antimicrobial resistance, and the documentation of infection rates in populations. This article examines how the state of (a) product quality, (b) pricing, and (c) development country manufacturing capacity, are affecting the supply of IVDs in Low-Income Countries (LICs). Data informing this work is derived from interviews with representatives of leading stakeholder organisations working in this space, and analysis of secondary literature. The findings of this analysis are that the supply of IVDs in LICs is undermined by (i) significant variation in product quality; (ii) inconsistent market demand from governments; (iii) limited opportunities for pooled procurement; (iv) a lack of transparency and consistency in product pricing; and (v) insufficient competition among producers capable of innovating for populations with limited purchasing power and low-resource settings. The article then examines four strategies for how these challenges can be overcome.

Amerindian genetic ancestry as a risk factor for tuberculosis in an amazonian population.

In recent years, the incidence of tuberculosis (TB) has declined worldwide, although this disease still occurs at relatively high rates in Amerindian populations. This suggests that the genetic ancestry of Amerindians may be an important factor in the development of infections, and may account for at least some of the variation in infection rates in the different populations. The present study investigated the potential influence of Amerindian genetic ancestry on susceptibility to tuberculosis in an Amazon population. The study included 280 patients diagnosed with tuberculosis and 138 asymptomatic hospital employees with no history of TB, but who were in contact with bacterially active TB patients. Ancestry analysis was run on a set of 61 Ancestry-Informative Markers to estimate European, African, and Amerindian genetic ancestry using STRUCTURE v2.2. The TB group had significantly higher Amerindian ancestry in comparison with the control group, and significantly lower European ancestry. Amerindian ancestry in the 20–60% range was found to be the principal risk factor for increased susceptibility to TB. The results of the study indicate that Amerindian ancestry is an important risk factor for susceptibility to TB in the admixed population of the Brazilian Amazon region.

COVID-19 Deaths Previsions With Deep Learning Sequence Prediction

In this study, the authors use deep learning sequence prediction models for the continuous monitoring of the epidemic while considering the potential impacts of Bacille Calmette-Guérin (BCG) vaccination and tuberculosis (TB) infection rates in populations. Three models were built based on the epidemic data evolution in several countries between the date of their first case and April 1, 2020. The data was based on 14 variables for cases prediction, 15 variables for recoveries prediction, and 16 variables for deaths prediction. Prevision results were very promising, and the suspicions on the BCG vaccination and TB infections rates' implications turned out to be warranted. The model can evolve by continuously updating and enriching data, adding the experiences of all affected countries.

Climate Factors and Wolbachia Infection Frequencies in Natural Populations of Drosophila melanogaster

The endosymbiotic bacteria Wolbachia are widespread in natural populations of Drosophila melanogaster, which is a cosmopolitan and synanthropic species. Various aspects of Wolbachia infection are studied in many arthropod species, including fruit flies. However, the influence of climatic factors on the level of Wolbachia infection in natural populations of fruit flies has not been studied in detail. The influence of mean temperature, precipitation, and potential evaporation was investigated on Wolbachia infection rates in ten D. melanogaster populations (collected in Europe) and newly obtained estimates were combined with the data from other studies for different continents and for different climatic zones (280 populations, 10 806 isofemale lines). The effect of climatic factors on the infection frequency was revealed. The highest infection rates are observed in the mean annual temperature range of 20–25°C, which corresponds to fly rearing conditions in the laboratory. The clinal distribution of Wolbachia infection rates in the Eurasian fruit fly populations was described. Logistic regression models showed that climatic factors have a stronger impact on bacterial infection rates within climatic zones rather than continents.

Association of single nucleotide polymorphism in NLRC3, NLRC5, HIP1, and LRP8 genes with fecal egg counts in goats naturally infected with Haemonchus contortus.

Haemonchus contortus is a common, intractably pathogenic and economically important gastrointestinal nematode for goat producers worldwide, especially in tropical and subtropical regions. The objective of this study is to identify single nucleotide polymorphisms (SNPs) of 12 candidate goat genes mainly related to the innate immune response associated with fecal egg counts (FECs) of Haemonchus contortus in goat as an indicator of the level of parasite infection. Phenotypic data including FEC and blood traits were recorded in 189 native goats from China and 191 ones from Bangladesh, respectively. Bangladeshi goats had significantly (P < 0.01) lower FEC compared to that of Chinese goats, suggesting higher susceptible and infection rates in Chinese goat populations. FEC was significantly positive correlated with body weight (r = 0.64, P < 0.01) and hemoglobin (r = 0.49, P < 0.01) value, but negative with pack cell volume (r = - 0.63, P < 0.05) in goats. Genotyping of SNPs was performed using a matrix-assisted laser desorption ionization time of flight mass spectrometry assay and a generalized linear model was used to evaluate the association between each SNP and goat FEC trait. Eleven novel SNPs in the NLRC3, NLRC5, HIP1, and LRP8, out of 46 variants from these 12 genes, were significantly associated with FEC of goats with a nominal significance level of P < 0.05. Of these 11 SNPs, linkage disequilibrium were revealed among SNPs in LRP8 (r2 = 0.87 to 1), between SNPs in NLRC3, NLRC5, and HIP1 (r2 = 0.96 to 0.99), respectively. Further, haplotypes within NLRC3, NLRC5, and HIP1 were significantly associated (P < 0.001) with FEC. In artificial challenge trail, quantitative real-time PCR exposed that the relative expression of mRNA was higher in the resistant group for NLRC3 (P < 0.01), LRP8 and HIP1 (P < 0.001) but lower in the resistant group for NLRC5 (P < 0.0001), compared to the susceptible group. The possible SNP markers and genes identified in this study could be potentially used in marker-assisted selection for breeding local goats breeds resistant to gastrointestinal nematode parasiteparticularly for Haemonchus contortus, and then for improving health and productivity of goat.

Phytoseiid predatory mites can disperse entomopathogenic fungi to prey patches

Recent studies have shown that predatory mites used as biocontrol agents can be loaded with entomopathogenic fungal conidia to increase infection rates in pest populations. Under laboratory conditions, we determined the capacity of two phytoseiid mites, Amblyseius swirskii and Neoseiulus cucumeris to deliver the entomopathogenic fungus Beauveria bassiana to their prey, Frankliniella occidentalis. Predatory mites were loaded with conidia and released on plants that had been previously infested with first instar prey clustered on a bean leaf. We examined each plant section to characterize the spatial distribution of each interacting organism. Our results showed that A. swirskii delivered high numbers of conidia to thrips infested leaves, thereby increasing the proportion of thrips that came into contact with the fungus. The effect was larger when thrips infestation occurred on young leaves than on old leaves. Neoseiulus cucumeris delivered less conidia to the thrips infested leaves. These patterns result from differences in foraging activity between predatory mite species. Amblyseius swirskii stayed longer on plants, especially within thrips colonies, and had a stronger suppressing effect on thrips than N. cucumeris. Our study suggests that loading certain predatory mite species with fungal conidia can increase their capacity to suppress thrips populations by combining predation and dispersing pathogens.

Postglacial colonization history reflects in the genetic structure of natural populations of Festuca rubra in Europe.

We conducted a large‐scale population genetic survey of genetic diversity of the host grass Festuca rubra s.l., which fitness can be highly dependent on its symbiotic fungus Epichloë festucae, to evaluate genetic variation and population structure across the European range. The 27 studied populations have previously been found to differ in frequencies of occurrence of the symbiotic fungus E. festucae and ploidy levels. As predicted, we found decreased genetic diversity in previously glaciated areas in comparison with nonglaciated regions and discovered three major maternal genetic groups: southern, northeastern, and northwestern Europe. Interestingly, host populations from Greenland were genetically similar to those from the Faroe Islands and Iceland, suggesting gene flow also between those areas. The level of variation among populations within regions is evidently highly dependent on the postglacial colonization history, in particular on the number of independent long‐distance seed colonization events. Yet, also anthropogenic effects may have affected the population structure in F. rubra. We did not observe higher fungal infection rates in grass populations with lower levels of genetic variability. In fact, the fungal infection rates of E. festucae in relation to genetic variability of the host populations varied widely among geographical areas, which indicate differences in population histories due to colonization events and possible costs of systemic fungi in harsh environmental conditions. We found that the plants of different ploidy levels are genetically closely related within geographic areas indicating independent formation of polyploids in different maternal lineages.