Supercooling Points of Adult Dermacentor variabilis (Acari: Ixodidae) From a Population Near the Northern Distribution Limit

2020 ◽  
Author(s):  
Matthew E M Yunik ◽  
Neil B Chilton
Keyword(s):  
Cold Hardiness ◽  
Dermacentor Variabilis ◽  
Subzero Temperatures ◽  
Host Seeking ◽  
Short Period ◽  
Significant Difference ◽  
Northern Distribution ◽  
Dog Tick ◽  
Provincial Park ◽  
Established Population

Abstract The northern distributional limit of Dermacentor variabilis Say, the American dog tick, is expanding in Saskatchewan and Manitoba (western Canada). The ability of D. variabilis to continue to expand its range northwards will depend upon the ability of individuals within populations at the species distributional edge to withstand very low temperatures during winter. One component of cold hardiness is the supercooling point (SCP), the temperature below 0°C at which an individual freezes. In this study, the SCP was determined for 94 questing D. variabilis adults (44 females and 50 males) from an established population near Blackstrap Provincial Park in Saskatchewan. SCP values ranged from −18.2 to −6.7°C, with a median of −13.3°C. This suggests that host-seeking D. variabilis adults differ in their ability to survive exposure to subzero temperatures, for at least a short period of time, without freezing. The distribution of SCPs was bimodal, but there was no significant difference in SCP values between female and male ticks, and no relationship between SCP and tick body weight. It remains to be determined what factors contribute to the variation in SCP values among questing D. variabilis adults.

scholarly journals The Correlation of Francisella tularensis on Size and Supercooling of Dermacentor variabilis

2018 ◽  
Vol 10 (2) ◽  
pp. 15
Author(s):  
Amal El Nabbout ◽  
Brittany J. Taylor ◽  
James Kho ◽  
Mandy Mitton ◽  
Tatiana Rossolimo
Keyword(s):  
Francisella Tularensis ◽  
Cold Hardiness ◽  
Dermacentor Variabilis ◽  
Physical Size ◽  
Significant Difference ◽  
Bacterium Species ◽  
Tick Survival ◽  
Study Support ◽  
Polymerase Chain ◽  
The Relationship

Overwintering tick survival is essential for the continuation of a tick’s lifecycle. Recent studies have found that infections with particular microorganisms can alter the physiology of ticks and, in some cases, increase their cold hardiness. To date, the influence of Francisella tularensis on Dermacentor variabilis (Say) has not been studied and thus the symbiosis between the two has been unknown. This study determined the infection rate of F. tularensis as well as examined the relationship between F. tularensis and the supercooling point (SCP) and size of D. variabilis of ticks from Nova Scotia, Canada. Local veterinarians provided adult ticks. The SCP of each tick was recorded using Logger Pro and infection status was found using Polymerase Chain Reaction. Of the 203 ticks tested, 9.8% were infected with F. tularensis. When the sexes were considered separately, 4% of males, 11.7% engorged females and 17.3% of non-engorged females were infected. Upon further analysis, a statistically significant difference was found between infected ticks and changes in thier SCPs, but there was no statistically significant difference between infected ticks and changes in size. This suggests that F. tularensis benefits D. variabilis by decreasing their SCPs, and thereby enhancing their overwintering capabilities. While other physiological influences of F. tularensis on D. variabilis remain unknown, the results from this study support previous research that bacterium species such as F. tularensis is able to influence the survivability of its tick host in the form of altering their freezing tolerance but does not affect the physical size of D. variabilis.

PARASITIZATION OF MEADOW VOLES, MICROTUS PENNSYLVANICUS (ORD), BY AMERICAN DOG TICKS, DERMACENTOR VARIABILIS (SAY), AND ADULT TICK MOVEMENT DURING HIGH HOST DENSITY1

1986 ◽  
Vol 21 (2) ◽  
pp. 102-113 ◽  
Author(s):  
J. F. Carroll ◽  
J. D. Nichols
Keyword(s):  
Population Density ◽  
Host Density ◽  
Adult Tick ◽  
Dermacentor Variabilis ◽  
Microtus Pennsylvanicus ◽  
Meadow Vole ◽  
Meadow Voles ◽  
Annual Basis ◽  
Host Seeking ◽  
Significant Difference

The numbers of host-seeking adult American dog ticks, Dermacentor variabilis (Say), in a sweet gum field in Maryland reflected changes in the population density of a host species, the meadow vole, Microtus pennsylvanicus (Ord), which within 1.5 yr fell from an estimated 157 to 8 voles on a 0.8 ha grid. During high vole density, there was no significant difference (P > 0.05) in tick burdens between sexes on an annual basis. Juvenile and subadult voles (< 33 g) harbored significantly fewer D. variabilis larvae and nymphs than did mature voles (> 33 g) on an annual basis. However, during periods of both peak host-seeking activity by D. variabilis larvae and nymphs and high host density nearly all the voles examined were infested. There was no evidence of a relationship between weight of adult voles and likelihood of parasitization by D. variabilis during months of moderate tick host-seeking activity. Of 163 adult D. variabilis recaptured ≥ one week after marking, 86 (52.7%) had moved > 3.8 m, 59 (36.2%) > 5.3 m.

scholarly journals Surveillance of Host-Seeking Ticks in the Flint Hills Region (USA) and Associations with Environmental Determinants

Parasitologia ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 137-147
Author(s):  
Mark Spare ◽  
Gunavanthi D. Boorgula ◽  
Dan Thomson ◽  
Jianfa Bai ◽  
Doug Goodin ◽  
...  
Keyword(s):  
Gulf Coast ◽  
Ixodes Scapularis ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Flint Hills ◽  
Host Seeking ◽  
The Usa ◽  
Gulf Coast Tick ◽  
The Times ◽  
Dog Tick

Diversity and phenology of host-seeking ticks were studied in the Flint Hills region of the USA, which is a prominent region for raising beef cattle. Between a two-year period from 2015–2017, ticks were collected using the dragging method from 9 distant locations, 6 of which were studied seasonally and 3 continuously throughout the study period. Of the 10,055 ticks collected, 76.5% were the Lonestar tick (Amblyomma americanum), 14% were American dog tick (Dermacentor variabilis), and 9.1% were Gulf Coast tick (A. maculatum). The blacklegged tick, Ixodes scapularis were also found, albeit in low numbers. The host-seeking activity of all three predominant tick species peaked once during the late spring, summer months in the region. The phenology of all ticks was positively associated with accumulated temperature and photoperiod. Additionally, the Normalized Vegetation Difference Index (NDVI) was associated with A. americanum, and saturation deficit and relative humidity were negatively associated with D. variabilis and A. maculatum tick phenology, respectively. This finding is useful to predict the times during a year in which cattle are at higher risk for exposure to these ticks and associated pathogens.

scholarly journals Tick Ecdysteroid Hormone, Global Microbiota/Rickettsia Signaling in the Ovary versus Carcass during Vitellogenesis in Part-Fed (Virgin) American Dog Ticks, Dermacentor variabilis

2021 ◽  
Vol 9 (6) ◽  
pp. 1242
Author(s):  
Loganathan Ponnusamy ◽  
Haley Sutton ◽  
Robert D. Mitchell ◽  
Daniel E. Sonenshine ◽  
Charles S. Apperson ◽  
...  
Keyword(s):  
Hormonal Regulation ◽  
Natural Populations ◽  
Blood Feeding ◽  
Dermacentor Variabilis ◽  
Transovarial Transmission ◽  
Rickettsia Species ◽  
Adult Females ◽  
Dog Tick ◽  
Total Bacteria

The transovarial transmission of tick-borne bacterial pathogens is an important mechanism for their maintenance in natural populations and transmission, causing disease in humans and animals. The mechanism for this transmission and the possible role of tick hormones facilitating this process have never been studied. Injections of physiological levels of the tick hormone, 20-hydroxyecdysone (20E), into part-fed (virgin) adult females of the American dog tick, Dermacentor variabilis, attached to the host caused a reduction in density of Rickettsia montanensis in the carcass and an increase in the ovaries compared to buffer-injected controls. This injection initiates yolk protein synthesis and uptake by the eggs but has no effect on blood feeding. Francisella sp. and R. montanensis were the predominant bacteria based on the proportionality in the carcass and ovary. The total bacteria load increased in the carcass and ovaries, and bacteria in the genus Pseudomonas increased in the carcass after the 20E injection. The mechanism of how the Rickettsia species respond to changes in tick hormonal regulation needs further investigation. Multiple possible mechanisms for the proliferation of R. montanensis in the ovaries are proposed.

scholarly journals Heterogeneity and effectiveness analysis of COVID-19 prevention and control in major cities in China through time-varying reproduction number estimation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qing Cheng ◽  
Zeyi Liu ◽  
Guangquan Cheng ◽  
Jincai Huang
Keyword(s):  
Prevention And Control ◽  
Large Scale ◽  
Reproduction Number ◽  
Correlation Method ◽  
Control Measures ◽  
Time Varying ◽  
Short Period ◽  
Significant Difference ◽  
Prevention And Control Measures ◽  
And Control

AbstractBeginning on December 31, 2019, the large-scale novel coronavirus disease 2019 (COVID-19) emerged in China. Tracking and analysing the heterogeneity and effectiveness of cities’ prevention and control of the COVID-19 epidemic is essential to design and adjust epidemic prevention and control measures. The number of newly confirmed cases in 25 of China’s most-affected cities for the COVID-19 epidemic from January 11 to February 10 was collected. The heterogeneity and effectiveness of these 25 cities’ prevention and control measures for COVID-19 were analysed by using an estimated time-varying reproduction number method and a serial correlation method. The results showed that the effective reproduction number (R) in 25 cities showed a downward trend overall, but there was a significant difference in the R change trends among cities, indicating that there was heterogeneity in the spread and control of COVID-19 in cities. Moreover, the COVID-19 control in 21 of 25 cities was effective, and the risk of infection decreased because their R had dropped below 1 by February 10, 2020. In contrast, the cities of Wuhan, Tianmen, Ezhou and Enshi still had difficulty effectively controlling the COVID-19 epidemic in a short period of time because their R was greater than 1.

Synganglion transcriptome and developmental global gene expression in adult females of the American dog tick, Dermacentor variabilis (Acari: Ixodidae)

2011 ◽  
Vol 20 (4) ◽  
pp. 465-491 ◽  
Author(s):  
B. W. Bissinger ◽  
K. V. Donohue ◽  
S. M. S. Khalil ◽  
C. M. Grozinger ◽  
D. E. Sonenshine ◽  
...  
Keyword(s):  
Gene Expression ◽  
Global Gene Expression ◽  
Dermacentor Variabilis ◽  
American Dog Tick ◽  
Adult Females ◽  
Dog Tick

scholarly journals Brood stock formation of the hermaphrodite finfish species Pagellus erythrinus (common Pandora) from fish reared in captivity

2004 ◽  
Vol 5 (1) ◽  
pp. 187 ◽  
Author(s):  
S.D. KLAOUDATOS ◽  
D.S. KLAOUDATOS
Keyword(s):  
Hormonal Treatment ◽  
Sex Reversal ◽  
Reproductive Period ◽  
Brood Stock ◽  
Pagellus Erythrinus ◽  
Short Period ◽  
Significant Difference ◽  
In Captivity ◽  
Fish Group ◽  
Common Pandora

Formation of brood stock is considered to be one of the most important operations in order to acquire eggs and fry from any promising candidate finfish species for aquaculture production. The sex reversal observed in hermaphrodite species adds to confusion and creates additional complications in forming a brood stock. The present study describes the efforts and the results of the brood stock formation of the hermaphrodite finfish species Pagellus erythrinus (common Pandora) from individuals aged between 4 and 5 years (TL>300mm) reared in floating cages. Six groups were formed (50 fish/group) in all of which females were present comprising 20 to 40% of the population. The presence of females was in contrast to the literature, which reported that sex reversal of the common Pandora is complete in naturally occurring populations with the absence of females in sizes of a total length greater than 220mm, indicating that in captivity sex reversal is not complete for this species. Four of the groups formed spawned under natural environmental conditions without hormonal treatment and the other two groups were administered a different dosage (250 and 500 IU/kg) of Human Chorionic Gonadotropin (HCG) to induce spawning. The reproductive period started in the middle of May and ended at the beginning of July and spontaneous spawning occurred in all groups. Egg release lasted for a mean period of one month for the groups that spawned without hormonal treatment with no significant difference in the number of viable eggs between groups. The groups that spawned under hormonal treatment released eggs for a period of six and seven days, for the group that spawned under the high and low hormonal treatment, respectively, with no significant difference in the number of viable eggs between them. The hormonal induced spawning resulted in egg release within a short period of time ideal for a hatchery. However, the number of viable eggs produced was significantly lower compared to the number of viable eggs produced from groups that spawned without hormonal treatment.

scholarly journals The impacts of anthropogenic disturbance on plant species richness in the freshwater lakes of Algonquin Provincial Park

SURG Journal ◽  
2017 ◽  
Vol 9 (1) ◽  
pp. 5-13
Author(s):  
Adrian Helmers ◽  
Alexis Platek ◽  
Melissa Ponte ◽  
Natalie Secen ◽  
Karl Cottenie
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Human Activity ◽  
Anthropogenic Disturbance ◽  
Negative Relationship ◽  
Access Point ◽  
Plant Species Richness ◽  
Significant Difference ◽  
The Impact ◽  
Provincial Park

This study quantified the impact of human activity on aquatic and shoreline plant species richness. We hypothesized that human activity at the shoreline would negatively impact plant species richness and that the extent of the impact would depend on the intensity of human activity. To test this, we sampled 11 lakes in Algonquin Provincial Park, of which five permitted motorboat access, and five permitted canoe access and prohibited motorboat access. The remaining lake, which had no designated access point for boats and was only accessible to researchers, acted as a control. To assess the impact of anthropogenic disturbance at each lake, we measured plant species richness in three 10 m by 2 m plots: a first plot at the access point, assumed to be the site of highest disturbance; a second at the site of intermediate disturbance, 30 m down shore from the access point; and a third at the site of lowest disturbance, 60 m down shore from the access point. We found a significant negative relationship between the level of disturbance and plant species richness, both in the motorboat-accessible and canoe access-only lakes. The control lake exhibited no correlation between disturbance level and plant species richness. However, there was no significant difference between motorboat-accessible and canoe access-only lakes in the relationship between disturbance level and plant species richness. Overall, this study highlights the consequences of anthropogenic disturbance on freshwater aquatic and shoreline plant communities, and provides a framework for future management and rehabilitation strategies.

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