scholarly journals Short-Term Selection to Diflubenzuron and Bacillus thuringiensis Var. Israelensis Differentially Affects the Winter Survival of Culex pipiens f. Pipiens and Culex pipiens f. Molestus (Diptera: Culicidae)

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 527
Author(s):  
Charalampos S. Ioannou ◽  
Christos Hadjichristodoulou ◽  
Maria A. Kyritsi ◽  
Nikos T. Papadopoulos
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Mosquito Control ◽  
Survival Rates ◽  
Winter Survival ◽  
Winter Period ◽  
Short Term ◽  
Term Selection ◽  
High Dependency ◽  
Successive Generations

The Culex pipiens (Diptera: Culicidae) mosquito is of high medical importance as it is considered the prime vector of West Nile virus. In Europe, this species consists of two forms, named pipiens and molestus, that exhibit substantial differences in their overwintering biology. Diflubenzuron (DFB) and Bacillus thuringiensis var. israelensis (Bti) are two of the most used larvicides in mosquito control, including that of Culex pipiens. The high dependency on these two larvicides poses major concerns for resistance development. The evolution and stability of resistance to insecticides has been associated with fitness costs that may be manifested under stressful conditions, such as the winter period. This study investigated how short-term selection of pipiens and molestus forms to both larvicides affect their overwintering success. Larvae from each form were subjected to the same selective pressure (80% mortality) for three successive generations with DFB and Bti. At the end of this process, the winter survival between the selected populations and the controls (colonies without selection) was determined for each form. Selection to both larvicides significantly reduced the winter survival rates of molestus but not of pipiens form, indicating potential differences in the persistence of the selected individuals from year to year between the two forms.

Short Term Selection to Diflubenzuron and Bacillus Thuringiensis Subsp. Israelensis Differentially Affects the Winter Survival of Culex Pipiens F. Pipiens and Culex Pipiens F. Molestus (Diptera: Culicidae)

2020 ◽  
Author(s):  
Charalampos S Ioannou ◽  
Christos Hadjichristodoulou ◽  
Maria A Kyritsi ◽  
Nikos T Papadopoulos
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Survival Rates ◽  
Fitness Cost ◽  
Winter Survival ◽  
Winter Period ◽  
Short Term ◽  
Term Selection ◽  
High Fitness ◽  
High Dependency

Abstract BackgroundThe Culex pipiens mosquito consists of two forms named pipiens and molestus that exhibit substantial differences in their biology including overwintering behavior. Diflubenzuron (DFB) and Bacillus thuringiensis subsp. israelensis (Bti) are among the most widely used larvicides for controlling Cx. pipiens populations. The high dependency on these two larvicides, pose major concerns for resistance development. The evolution and stability of tolerance/resistance to insecticides has been associated with fitness costs that may be manifested under stressful conditions such as the winter period. This study aimed to investigate how short term selection of pipiens and molestus forms to both larvicides affect their susceptibility and their overwintering success.MethodsColonies of both forms of Cx. pipiens were established from the same area. Following standard protocols, the efficacy of both larvicides was determined for each mosquito population. Then, larvae from each form, were selected for three successive generations by applying fixed doses corresponding to IE80 (Inhibition of adult Emergence) and LC80 (Lethal Concentration) for DFB and Bti, respectively. At the end of this process, the susceptibility levels and the winter survival of the selected populations relative to controls (colonies that received no selection) were determined.ResultsContrary to Bti, selection with DFB induced different susceptibility levels between the two forms of Cx. pipiens. The selected populations of Cx. pipiens f. molestus to both larvicides exhibited a high fitness cost in terms of reduced winter larval survival rates relative to control. Moreover, the obtained adults of the Bti selected population experienced significantly shorter lifespan compared to control and DFB selected population. On the other hand, selection with both DFB and Bti had no apparent effects on Cx. pipiens f. pipiens female winter survival rates relative to control. Furthermore, the reproductive parameters and the longevity of the overwintered females were similar between the selected populations and the control. ConclusionsOur findings reveal that sort term selection to DFB and Bti induces a high fitness cost on the winter survival of Cx. pipiens f. molestus but not of pipiens form, suggesting potential differences on the persistence of tolerant individuals from year to year between the two forms.

scholarly journals Resistance Development to Diflubenzuron and Bacillus Thuringiensis Subsp. Israelensis of Culex Pipiens f. Pipiens and Culex Pipiens f. Molestus (Diptera: Culicidae) and its Effects on Their Winter Survival

2020 ◽  
Author(s):  
Charalampos Ioannou ◽  
Christos Hadjichristodoulou ◽  
Maria A. Kyritsi ◽  
Nikos T. Papadopoulos
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Survival Rates ◽  
Larval Survival ◽  
Winter Survival ◽  
World Health ◽  
Winter Period ◽  
Fitness Costs ◽  
Resistance Development ◽  
High Dependency

Abstract Background: The Culex pipiens mosquito consists of two forms named pipiens and molestus that exhibit substantial differences in their biology including overwintering behavior. Diflubenzuron (DFB) and Bacillus thuringiensis subsp. israelensis (Bti) are among the most widely used larvicides for controlling Cx. pipiens populations. The high dependency on these two larvicides, pose major concerns for resistance development. The evolution and stability of resistance to insecticides has been associated with fitness costs that may be manifested under stressful conditions such as the winter period. The aim of the present study was to explore the resistance development of pipiens and molestus forms to both larvicides and its potential fitness costs on their winter survival.Methods: Colonies of both forms of Cx. pipiens were established from the same area. Following the World Health Organization protocols (WHO), the efficacy of both larvicides was determined for each mosquito population. Then, larvae from each form were selected for three successive generations by applying fixed doses corresponding to IE80 (IE: Inhibition of adult Emergence) and LC80 (LC: Lethal Concentration) for DFB and Bti respectively. At the end of this process, the resistance levels and the winter survival of the selected populations relative to controls (colonies that received no selection) were determined.Results: Contrary to Bti, selection with DFB induced different levels of resistance between the two forms of Cx. pipiens. The selected populations of Cx. pipiens f. molestus to both larvicides exhibited a high fitness cost in terms of reduced winter larval survival rates relative to control. Moreover, the obtained adults of the Bti selected population experienced significantly shorter lifespan compared to control and DFB selected population. On the other hand, selection with both DFB and Bti had no apparent effects on Cx. pipiens f. pipiens female winter survival rates relative to control. Furthermore, the reproductive parameters and the longevity of the overwintered females were similar between the selected populations and the control. Conclusions: Our findings are expected to contribute on the better understanding of the resistance development and evolution of the two forms of Cx. pipiens to DFB and Bti allowing the adoption of appropriate resistance management strategies.

scholarly journals Microbiota and transcriptome changes of Culex pipiens pallens larvae exposed to Bacillus thuringiensis israelensis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruiling Zhang ◽  
Wenjuan Liu ◽  
Qian Zhang ◽  
Xinyu Zhang ◽  
Zhong Zhang
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Mosquito Control ◽  
Sphingolipid Metabolism ◽  
Glutathione Metabolism ◽  
Control Group ◽  
Culex Pipiens Pallens ◽  
Bacillus Thuringiensis Israelensis ◽  
Epidemic Encephalitis ◽  
Pipiens Pallens

AbstractCulex pipiens pallens is an important vector of lymphatic filariasis and epidemic encephalitis. Mosquito control is the main strategy used for the prevention of mosquito-borne diseases. Bacillus thuringiensis israelensis (Bti) is an entomopathogenic bacterium widely used in mosquito control. In this study, we profiled the microbiota and transcriptional response of the larvae of Cx. pipiens pallens exposed to different concentrations of Bti. The results demonstrated that Bti induced a significant effect on both the microbiota and gene expression of Cx. pipiens pallens. Compared to the control group, the predominant bacteria changed from Actinobacteria to Firmicutes, and with increase in the concentration of Bti, the abundance of Actinobacteria was gradually reduced. Similar changes were also detected at the genus level, where Bacillus replaced Microbacterium, becoming the predominant genus in Bti-exposed groups. Furthermore, alpha diversity analysis indicated that Bti exposure changed the diversity of the microbota, possibly because the dysbiosis caused by the Bti infection inhibits some bacteria and provides opportunities to other opportunistic taxa. Pathway analysis revealed significant enhancement for processes associated with sphingolipid metabolism, glutathione metabolism and glycerophospholipid metabolism between all Bti-exposed groups and control group. Additionally, genes associated with the Toll and Imd signaling pathway were found to be notably upregulated. Bti infection significantly changed the bacterial community of larvae of Cx. pipiens pallens.

Influence of Planting Stock Clove Size, Nitrogen Rate, and Planting Method on Elephant Garlic Production

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 517f-518
Author(s):  
Jeanine M. Davis
Keyword(s):  
Survival Rates ◽  
Ground Level ◽  
Winter Survival ◽  
Nitrogen Rate ◽  
Planting Stock ◽  
Mild Winter ◽  
Allium Ampeloprasum ◽  
Planting Methods ◽  
Planting Method ◽  
Nitrogen Rates

To produce large elephant garlic (Allium ampeloprasum L.) bulbs in the southeastern United States, stock cloves must be planted in the fall. During extremely cold winters, however, winter survival rates can be very low. A 2-year study was undertaken to examine practices to increase winter survival rates. Two clove sizes (≤20 g or >20 g), three nitrogen rates (112, 224, and 336 kg/ha), and three planting methods (flat, mulched, and hilled) were tested in a RCB design with four replications. For all planting methods, cloves were set in a shallow trench and covered with soil to ground level. This was also the flat treatment. For the mulched treatment, 7 cm of straw was spread on top. For the hilled treatment, soil was mounded 10 to 15 cm high over the ground level. Cloves were planted in early October and harvested in mid-June. Use of large planting stock cloves increased winter survival rates during the harsh winter, but had no effect during the mild winter. Both years, winter survival was reduced with the flat treatment. Yields of marketable bulbs were 4 to 5 times higher when >20 g cloves were planted than when ≤20 g cloves were used. Nitrogen rate and planting method had no effect on yields. The >20 g cloves also produced larger bulbs than the smaller cloves. Of the three planting methods, the flat treatment produced the smallest bulbs. Bulbs were much larger following the mild winter than the harsh winter.

scholarly journals Robotic and laparoscopic liver surgery for colorectal liver metastases: an experience from a German Academic Center

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Mirhasan Rahimli ◽  
Aristotelis Perrakis ◽  
Vera Schellerer ◽  
Andrew Gumbs ◽  
Eric Lorenz ◽  
...  
Keyword(s):  
Abdominal Surgery ◽  
Minimally Invasive ◽  
Liver Surgery ◽  
Colorectal Liver Metastases ◽  
Survival Rates ◽  
Long Term Outcomes ◽  
Short Term ◽  
Minimally Invasive Liver Surgery ◽  
Previous Abdominal Surgery

Abstract Background Minimally invasive liver surgery (MILS) in the treatment of colorectal liver metastases (CRLM) is increasing in incidence. The aim of this work was to present our experience by reporting short-term and long-term outcomes after MILS for CRLM with comparative analysis of laparoscopic (LLS) and robotic liver surgery (RLS). Methods Twenty-five patients with CRLM, who underwent MILS between May 2012 and March 2020, were selected from our retrospective registry of minimally invasive liver surgery (MD-MILS). Thirteen of these patients underwent LLS and 12 RLS. Short-term and long-term outcomes of both groups were analyzed. Results Operating time was significantly longer in the RLS vs. the LLS group (342.0 vs. 200.0 min; p = 0.004). There was no significant difference between the laparoscopic vs. the robotic group regarding length of postoperative stay (8.8 days), measured blood loss (430.4 ml), intraoperative blood transfusion, overall morbidity (20.0%), and liver surgery related morbidity (4%). The mean BMI was 27.3 (range from 19.2 to 44.8) kg/m2. The 30-day mortality was 0%. R0 resection was achieved in all patients (100.0%) in RLS vs. 10 patients (76.9%) in LLS. Major resections were carried out in 32.0% of the cases, and 84.0% of the patients showed intra-abdominal adhesions due to previous abdominal surgery. In 24.0% of cases, the tumor was bilobar, the maximum number of tumors removed was 9, and the largest tumor was 8.5 cm in diameter. The 1-, 3- and 5-year overall survival rates were 84, 56.9, and 48.7%, respectively. The 1- and 3-year overall recurrence-free survival rates were 49.6 and 36.2%, respectively, without significant differences between RLS vs. LLS. Conclusion Minimally invasive liver surgery for CRLM is safe and feasible. Minimally invasive resection of multiple lesions and large tumors is also possible. RLS may help to achieve higher rates of R0 resections. High BMI, previous abdominal surgery, and bilobar tumors are not a barrier for MILS. Laparoscopic and robotic liver resections for CRLM provide similar long-term results which are comparable to open techniques.

Evolution of Surgical Approaches in the Treatment of Petroclival Meningiomas: A Retrospective Review

2007 ◽  
Vol 61 (suppl_5) ◽  
pp. ONS202-ONS211 ◽  
Author(s):  
Nicholas C. Bambakidis ◽  
U. Kumar Kakarla ◽  
Louis J. Kim ◽  
Peter Nakaji ◽  
Randall W. Porter ◽  
...  
Keyword(s):  
Survival Rates ◽  
Progression Free Survival ◽  
Surgical Approaches ◽  
Single Institution ◽  
Short Term ◽  
Total Resection ◽  
Free Survival ◽  
Petroclival Meningioma ◽  
Petroclival Meningiomas

Abstract Objective: We examined the surgical approaches used at a single institution to treat petroclival meningioma and evaluated changes in method utilization over time. Methods: Craniotomies performed to treat petroclival meningioma between September of 1994 and July of 2005 were examined retrospectively. We reviewed 46 patients (mean follow-up, 3.6 yr). Techniques included combined petrosal or transcochlear approaches (15% of patients), retrosigmoid craniotomies with or without some degree of petrosectomy (59% of patients), orbitozygomatic craniotomies (7% of patients), and combined orbitozygomatic-retrosigmoid approaches (19% of patients). In 18 patients, the tumor extended supratentorially. Overall, the rate of gross total resection was 43%. Seven patients demonstrated progression over a mean of 5.9 years. No patients died. At 36 months, the progression-free survival rate for patients treated without petrosal approaches was 96%. Of 14 patients treated with stereotactic radiosurgery, none developed progression. Conclusion: Over the study period, a diminishing proportion of patients with petroclival meningioma were treated using petrosal approaches. Utilization of the orbitozygomatic and retrosigmoid approaches alone or in combination provided a viable alternative to petrosal approaches for treatment of petroclival meningioma. Regardless of approach, progression-free survival rates were excellent over short-term follow-up period.

scholarly journals An Efficient Prediction Model for Water Discharge in Schoharie Creek, NY

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Katerina G. Tsakiri ◽  
Antonios E. Marsellos ◽  
Igor G. Zurbenko
Keyword(s):  
New York ◽  
Time Series ◽  
Water Discharge ◽  
Winter Period ◽  
Statistical Methodology ◽  
Summer Period ◽  
Short Term ◽  
Efficient Prediction ◽  
Climatic Time Series

Flooding normally occurs during periods of excessive precipitation or thawing in the winter period (ice jam). Flooding is typically accompanied by an increase in river discharge. This paper presents a statistical model for the prediction and explanation of the water discharge time series using an example from the Schoharie Creek, New York (one of the principal tributaries of the Mohawk River). It is developed with a view to wider application in similar water basins. In this study a statistical methodology for the decomposition of the time series is used. The Kolmogorov-Zurbenko filter is used for the decomposition of the hydrological and climatic time series into the seasonal and the long and the short term component. We analyze the time series of the water discharge by using a summer and a winter model. The explanation of the water discharge has been improved up to 81%. The results show that as water discharge increases in the long term then the water table replenishes, and in the seasonal term it depletes. In the short term, the groundwater drops during the winter period, and it rises during the summer period. This methodology can be applied for the prediction of the water discharge at multiple sites.

Factors Affecting Winter Survival of Johnsongrass (Sorghum halepense) Rhizomes

1991 ◽  
Vol 5 (1) ◽  
pp. 108-110 ◽  
Author(s):  
Robert G. Hartzler ◽  
Art Gover ◽  
Joanne Stellingwerf
Keyword(s):  
Survival Rates ◽  
Winter Survival ◽  
Sorghum Halepense ◽  
Factors Affecting ◽  
Rhizome Biomass ◽  
Depth Of Burial

There were no differences in johnsongrass rhizome winter survival at central and southeastern locations in Pennsylvania in 1988 or 1989. At a 6-cm depth of burial, survival rates of 5 and 25% were found for rhizome segments 7.5 and 15.0 cm in length, respectively. Survival rates for rhizomes buried 25 cm averaged 86%, with no difference in survival between rhizome lengths. The majority of rhizome biomass produced by the biotype used in these studies was found at soil depths allowing a high percentage of survival.

scholarly journals Distribution of Bacillus thuringiensis subsp. israelensis in Soil of a Swiss Wetland Reserve after 22 Years of Mosquito Control

2011 ◽  
Vol 77 (11) ◽  
pp. 3663-3668 ◽  
Author(s):  
Valeria Guidi ◽  
Nicola Patocchi ◽  
Peter Lüthy ◽  
Mauro Tonolla
Keyword(s):  
Spatial Distribution ◽  
Bacillus Thuringiensis ◽  
Confidence Interval ◽  
Quantitative Pcr ◽  
Mosquito Control ◽  
Soil Samples ◽  
Sampling Point ◽  
Content Type ◽  
Large Numbers ◽  
Continuous Accumulation

ABSTRACTRecurrent treatments withBacillus thuringiensissubsp.israelensisare required to control the floodwater mosquitoAedes vexansthat breeds in large numbers in the wetlands of the Bolle di Magadino Reserve in Canton Ticino, Switzerland. Interventions have been carried out since 1988. In the present study, the spatial distribution of restingB. thuringiensissubsp.israelensisspores in the soil was measured. TheB. thuringiensissubsp.israelensisconcentration was determined in soil samples collected along six transects covering different elevations within the periodically flooded zones. A total of 258 samples were processed and analyzed by quantitative PCR that targeted an identical fragment of 159 bp for theB. thuringiensissubsp.israelensis cry4Aaandcry4Bagenes.B. thuringiensissubsp.israelensisspores were found to persist in soils of the wetland reserve at concentrations of up to 6.8 log per gram of soil. Continuous accumulation due to regular treatments could be excluded, as the decrease in spores amounted to 95.8% (95% confidence interval, 93.9 to 97.7%). The distribution of spores was correlated to the number ofB. thuringiensissubsp.israelensistreatments, the elevation of the sampling point, and the duration of the flooding periods. The number ofB. thuringiensissubsp.israelensistreatments was the major factor influencing the distribution of spores in the different topographic zones (P< 0.0001). These findings indicated thatB. thuringiensissubsp.israelensisspores are rather immobile after their introduction into the environment.

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