scholarly journals Host in reserve: the role of common shrews (Sorex araneus) as a stable supplementary source of tick hosts in small mammal communities influenced by rodent population cycles

2021 ◽  
Author(s):  
Nicolas De Pelsmaeker ◽  
Lars Korslund ◽  
Øyvind Steifetten
Keyword(s):  
Population Size ◽  
Population Cycles ◽  
Sorex Araneus ◽  
Host Population ◽  
Climatic Conditions ◽  
Myodes Glareolus ◽  
Northern Latitudes ◽  
Annual Population ◽  
Southern Norway

In recent decades, warming temperatures and changes in land use are supposed to have enabled several tick species to expand their distribution limit northwards. The progression of ticks to new areas may introduce new and emerging tick-borne pathogens as well as increase existing diseases. Aside from climatic conditions, ticks are dependent on hosts for survival, and rodents often act as important hosts for ticks and as pathogen reservoirs. At northern latitudes, rodents often undergo multi-annual population cycles, and the periodic absence of hosts may inhibit the further progression of ticks. We investigated the potential role of common shrews (Sorex araneus) to serve as a stable host source to immature life stages of a generalist tick Ixodes ricinus and a specialist tick I. trianguliceps, during decreasing abundances of bank voles (Myodes glareolus). We tested whether ticks would have a propensity to parasitize a certain host type dependent on host population size and composition in two high latitude locations in southern Norway, by comparing tick burdens on trapped animals. We found that I. ricinus larvae showed an equal propensity to parasitize both host types as the host population composition changed, but voles had a higher level of parasitism by nymphs (p< 0.004). An overall larger host population size favored the parasitism of voles by larvae (p= 0.027), but not by nymphs (p= 0.074). I. trianguliceps larvae showed a higher propensity to parasitize shrews, regardless of host population size or composition (p= 0.004), while nymphs parasitized shrews more as vole abundance increased (p= 0.002). The results indicate that common shrews may have the potential to act as a replacement host during periods of low rodent availability, but long-term observations encompassing complete rodent cycles may determine whether shrews are able to maintain tick range expansion despite low rodent availability.

Can management regulate the population size of wild reindeer (Rangifer tarandus) through harvest?

2012 ◽  
Vol 90 (2) ◽  
pp. 163-171 ◽  
Author(s):  
O. Strand ◽  
E.B. Nilsen ◽  
E.J. Solberg ◽  
J.C.D. Linnell
Keyword(s):  
Population Size ◽  
Rangifer Tarandus ◽  
Small Population ◽  
Population Estimates ◽  
Relative Role ◽  
Harvest Data ◽  
Closed Populations ◽  
Southern Norway ◽  
Wild Reindeer

We analyzed a 51-year time series of harvest data from a small population of wild mountain reindeer ( Rangifer tarandus (L., 1758)) in southern Norway and examined the relative role of biological and management related processes as drivers of its population dynamics. The population is monitored annually to obtain information on population size and structure, and since 1980, managers have attempted to stabilize the population at about 1.1 reindeer/km2. The harvest increased at a higher rate than the population size and was thus probably sufficient to not only limit but also regulate population size. Phase plot analyses showed that the population has varied around a density attractor of about 1.0 reindeer/km2 since 1980 and is therefore close to the targeted population size of 1.1 reindeer/km2. However, the annual harvest explained only 49% of the variation in population growth rate (λ) in a linear regression model, despite relatively low variation in population productivity (proportion of calves). Between 1999 and 2006, the population in Forolhogna declined by almost 50% before recovering to its previous size. We suggest that both imprecise population estimates and high harvest effectiveness at reduced population densities contributed to this decline. As such, this study points to some of the obstacles managers are facing when trying to stabilize productive ungulate populations even when they live in closed populations and in stable, predator-free environments.

scholarly journals Characteristics of Phomopsis juglandina (Sacc.) Hohn. Associated with Dieback of Walnut in the Climatic Conditions of Southern Romania

Agronomy ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 46
Author(s):  
Cristina Mihaescu ◽  
Daniel Dunea ◽  
Adrian Gheorghe Bășa ◽  
Loredana Neagu Frasin
Keyword(s):  
Growth Temperature ◽  
Potential Evapotranspiration ◽  
Optimal Growth ◽  
Climatic Conditions ◽  
Cultural Characteristics ◽  
Optimal Growth Temperature ◽  
Conidial State ◽  
Optimal Ph

Phomopsis juglandina (Sacc.) Höhn., which is the conidial state of Diaporthe juglandina (Fuckel) Nitschke, and the main pathogen causing the dieback of branches and twigs of walnut was recently detected in many orchards from Romania. The symptomatological, morphological, ultrastructural, and cultural characteristics, as well as the pathogenicity of an isolate of this lignicolous fungus, were described and illustrated. The optimum periods for infection, under the conditions prevailing in Southern Romania, mainly occur in the spring (April) and autumn months (late September-beginning of October). Strong inverse correlations (p < 0.001) were found between potential evapotranspiration and lesion lengths on walnut branches in 2019. The pathogen forms two types of phialospores: alpha and beta; the role of beta phialospores is not well known in pathogenesis. In Vitro, the optimal growth temperature of mycelial hyphae was in the range of 22–26 °C, and the optimal pH is 4.4–7. This pathogen should be monitored continuously due to its potential for damaging infestations of intensive plantations.

scholarly journals Population Density or Populations Size. Which Factor Determines Urban Traffic Congestion?

2021 ◽  
Vol 13 (8) ◽  
pp. 4280
Author(s):  
Yu Sang Chang ◽  
Sung Jun Jo ◽  
Yoo-Taek Lee ◽  
Yoonji Lee
Keyword(s):  
Population Density ◽  
Population Size ◽  
Traffic Congestion ◽  
Critical Role ◽  
Small Population ◽  
High Density ◽  
Urban Traffic ◽  
Contradictory Result ◽  
Low Density

A large number of articles have documented that as population density of cities increases, car use declines and public transit use rises. These articles had a significant impact of promoting high-density compact urban development to mitigate traffic congestion. Another approach followed by other researchers used the urban scaling model to indicate that traffic congestion increases as population size of cities increases, thus generating a possible contradictory result. Therefore, this study examines the role of both density and population size on traffic congestion in 164 global cities by the use of Stochastic Impacts by Regression on Population, Affluence and Technology model. We divide 164 cities into the two subgroups of 66 low density cities and 98 high density cities for analysis. The findings from the subgroups analysis indicated a clear-cut difference on the critical role of density in low-density cities and the exclusive role of population size in high-density cities. Furthermore, using threshold regression model, 164 cities are divided into the two regions of large and small population cities to determine population scale advantage of traffic congestion. Our findings highlight the importance of including analysis of subgroups based on density and/or population size in future studies of traffic congestion.

Touring for peace: the role of dual-narrative tours in creating transnational activists

2019 ◽  
Vol 5 (2) ◽  
pp. 200-218 ◽  
Author(s):  
Emily Maureen Schneider
Keyword(s):  
Attitude Change ◽  
Past Research ◽  
Host Population ◽  
Contact Hypothesis ◽  
Racial Groups ◽  
Content Type ◽  
Governmental Organizations ◽  
Non Governmental Organizations ◽  
Peace And Justice

Purpose Scholarship on the contact hypothesis and peacebuilding suggests that contact with marginalized ethnic and racial groups may reduce prejudice and improve opportunities for conflict resolution. Through a study of dual-narrative tours to Israel/Palestine, the purpose of this paper is to address two areas of the debate surrounding this approach to social change. First, past research on the effectiveness of contact-based tourism as a method to change attitudes is inconclusive. Travel to a foreign country has been shown to both improve and worsen tourists’ perceptions of a host population. Second, few scholars have attempted to link contact-based changes in attitudes to activism. Design/methodology/approach Through an analysis of 218 post-tour surveys, this study examines the role of dual-narrative tours in sparking attitude change that may facilitate involvement in peace and justice activism. Surveys were collected from the leading “dual-narrative” tour company in the region, MEJDI. Dual-narrative tours uniquely expose mainstream tourists in Israel/Palestine to Palestinian perspectives that are typically absent from the majority of tours to the region. This case study of dual-narrative tours therefore provides a unique opportunity to address the self-selecting bias, as identified by contact hypothesis and tourism scholars, in order to understand the potential impacts of exposure to marginalized narratives. Findings The findings of this study suggest that while these tours tend to engender increased support for Palestinians over Israelis, their most salient function appears to be the cultivation of empathy for “both sides” of the conflict. Similarly, dual-narrative tours often prompt visitors to understand the conflict to be more complex than they previously thought. In terms of activism, tourists tend to prioritize education-based initiatives in their plans for post-tour political engagement. In addition, a large number of participants articulated commitments to support joint Israeli–Palestinian non-governmental organizations and to try to influence US foreign policy to be more equitable. Originality/value These findings complicate debates within the scholarship on peacebuilding as well as within movements for social justice in Israel/Palestine. While programs that equate Israeli and Palestinian perspectives are often criticized for reinforcing the status quo, dual-narrative tours appear to facilitate nuance and universalism while also shifting tourists toward greater identification with an oppressed population. Together, these findings shed light on the ability of tourism to facilitate positive attitude change about a previously stigmatized racial/ethnic group, as well as the power of contact and exposure to marginalized narratives to inspire peace and justice activism.

Parasite infection and host dynamics in a naturally fluctuating rodent population

2012 ◽  
Vol 90 (9) ◽  
pp. 1149-1160 ◽  
Author(s):  
J.C. Winternitz ◽  
M.J. Yabsley ◽  
S.M. Altizer
Keyword(s):  
Population Density ◽  
Experimental Studies ◽  
Host Density ◽  
Positive Association ◽  
Population Cycles ◽  
Host Population ◽  
Reproductive Status ◽  
Vole Cycles ◽  
Host Infection ◽  
The Impact

Parasites can both influence and be affected by host population dynamics, and a growing number of case studies support a role for parasites in causing or amplifying host population cycles. In this study, we examined individual and population predictors of gastrointestinal parasitism on wild cyclic montane voles ( Microtus montanus (Peale, 1848)) to determine if evidence was consistent with theory implicating parasites in population cycles. We sampled three sites in central Colorado for the duration of a multiannual cycle and recorded the prevalence and intensity of directly transmitted Eimeria Schneider, 1875 and indirectly transmitted cestodes from a total of 267 voles. We found significant associations between host infection status, individual traits (sex, age, and reproductive status) and population variables (site, trapping period, and population density), including a positive association between host density and cestode prevalence, and a negative association between host density and Eimeria prevalence. Both cestode and Eimeria intensity correlated positively with host age, reproductive status, and population density, but neither parasite was associated with poorer host condition. Our findings suggest that parasites are common in this natural host, but determining their potential to influence montane vole cycles requires future experimental studies and long-term monitoring to determine the fitness consequences of infection and the impact of parasite removal on host dynamics.

HAS PSYCHOLOGIC MALNUTRITION TAKEN THE PLACE OF RICKETS AND SCURVY IN CONTEMPORARY PEDIATRIC PRACTICE?

PEDIATRICS ◽  
1963 ◽  
Vol 31 (6) ◽  
pp. 909-918
Author(s):  
Nathan B. Talbot
Keyword(s):  
Sixteenth Century ◽  
Lemon Juice ◽  
Climatic Conditions ◽  
Northern Europe ◽  
Scientific Medicine ◽  
Pediatric Practice ◽  
Therapeutic Value ◽  
High Prevalence ◽  
The Baltic

WHILE MEDICAL HISTORIANS cannot provide us with accurate statistics concerning the incidence of rickets and scurvy in centuries past, they leave little room for doubt about the high prevalence of these disorders prior to the advent of modern scientific medicine. Thus, Castiglione has written that in the sixteenth century scurvy raged throughout northern Europe, in Scandinavia, on the shores of the Baltic, and in the interior of Germany. It is interesting to note, however, that Jacques Cartier, whose sailors had been ravaged by scurvy, learned in 1536 from the Indians that the malady could be cured by juices of the almeda tree. This was 200 years before James Lind demonstrated the curative effects of lemon juice in his treatise on scurvy published in 1753 and almost 400 years before ascorbic acid, which was isolated by Szent-Gyorgi in 1928, was recognized to be vitamin C by Waugh and King in 1932. Rickets, likewise, was occurring in a large portion of children prior to the discovery of the existence of vitamin D by Hess, Steinbock, and Windaus in 1918, of its therapeutic value by Mellanby in 1919, of the equivalent role of sunlight by Hess in 1921, and of the chemical composition of the vitamins by Windaus in 1922. But 200 years earlier Friedrick Hoffman had the answer to the control of this disease almost in hand. He attached much importance to climatic conditions as a factor in rickets, noting that if anything is specially powerful in producing this affliction, it is a surrounding atmosphere of cold foggy air. He cited as striking evidence of this the famous emporium of England, London, which he found to be specially apt to produce and foster this disease.

On Approaches to Taking into Account the Risks of Changing Climatic Conditions when Planning and Implementing Oil and Gas Projects

2021 ◽  
Vol 18 (1) ◽  
pp. 52-65
Author(s):  
P. N. Mikheev
Keyword(s):  
Climate Change ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Climatic Conditions ◽  
Qualitative Assessment ◽  
Physical Factors ◽  
Gas Industry ◽  
Climate Risks ◽  
The Impact

The article discusses issues related to the impact of climate change on the objects of the oil and gas industry. The main trends in climate change on a global and regional (on the territory of Russian Federation) scale are outlined. Possible approaches to the identification and assessment of climate risks are discussed. The role of climatic risks as physical factors at various stages of development and implementation of oil and gas projects is shown. Based on the example of oil and gas facilities in the Tomsk region, a qualitative assessment of the level of potential risk from a weather and climatic perspective is given. Approaches to creating a risk management and adaptation system to climate change are presented.

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