scholarly journals Successful suppression of a field population of Ae. aegypti mosquitoes using a novel biological vector control strategy is associated with significantly lower incidence of dengue

2019 ◽  
Author(s):  
Lisiane C Poncio ◽  
Filipe A dos Anjos ◽  
Deborah A de Oliveira ◽  
Débora Rebechi ◽  
Rodrigo N de Oliveira ◽  
...  
Keyword(s):  
Vector Control ◽  
Lower Incidence ◽  
Large Scale ◽  
Control Area ◽  
Environmentally Benign ◽  
Mosquito Population ◽  
Mosquito Vector ◽  
Sterile Male ◽  
Treated Area ◽  
Male Mosquitoes

AbstractBackgroundDespite extensive efforts to prevent recurrent Aedes-borne arbovirus epidemics, there is a steady rise in their global incidence. Vaccines/treatments show very limited efficacy and together with the emergence of mosquito resistance to insecticides, it has become urgent to develop alternative solutions for efficient, sustainable and environmentally benign mosquito vector control. Here we present a new Sterile Insect Technology (SIT)-based program that uses large-scale releases of sterile male mosquitoes produced by a highly effective, safe and environmentally benign method.Methods and findingsTo test the efficacy of this approach, a field trial was conducted in a Brazilian city (Jacarezinho), which presented a history of 3 epidemics of dengue in the past decade. Sterile male mosquitoes were produced from a locally acquired Aedes aegypti colony, and releases were carried out on a weekly basis for seven months in a predefined area. This treated area was matched to a control area, in terms of size, layout, historic mosquito infestation index, socioeconomic patterns and comparable prevalence of dengue cases in past outbreaks. Releases of sterile male mosquitoes resulted in up to 91.4% reduction of live progeny of field Ae. aegypti mosquitoes recorded over time. The reduction in the mosquito population was corroborated by the standard monitoring system (LIRAa index) as determined by the local municipality, which found that our treated neighborhoods were almost free of Ae. aegypti mosquitoes after 5 months of release, whereas neighborhoods adjacent to the treated area and the control neighborhoods were highly infested. Importantly, when a dengue outbreak started in Jacarezinho in March 2019, the effective mosquito population suppression was shown to be associated with a far lower incidence of dengue in the treated area (16 cases corresponding to 264 cases per 100,000 inhabitants) almost 16 times lower than the dengue incidence in the control area (198 cases corresponding to 4,360 dengue cases per 100,000 inhabitants).ConclusionsOur data present the first demonstration that a SIT-based intervention has the potential to prevent the spread of dengue, opening exciting new opportunities for preventing mosquito-borne disease.

Novel Sterile Insect Technology (SIT) program results in suppression of a field mosquito population and subsequently to reduced incidence of dengue

2021 ◽  
Author(s):  
Lisiane Castro Poncio ◽  
Filipe Apolinário dos Anjos ◽  
Deborah A de Oliveira ◽  
Débora Rebechi ◽  
Rodrigo Neves de Oliveira ◽  
...  
Keyword(s):  
Successful Implementation ◽  
Mosquito Vector ◽  
Sterile Male ◽  
Double Stranded Rna ◽  
Treated Area ◽  
And Control ◽  
Alternative Solutions ◽  
Male Mosquitoes ◽  
Aegypti Population ◽  
No Releases

Abstract Background There is a steady rise in the global incidence of Aedes-borne arbovirus disease. It has become urgent to develop alternative solutions for mosquito vector control. We developed a new method of sterilization of male mosquitoes, with the goal to suppress a local Aedes aegypti population and to prevent the spread of dengue. Methods Sterile male mosquitoes were produced from a locally acquired Ae. aegypti colony by using a treatment that includes double-stranded RNA and thiotepa. A field study was conducted, with sterile mosquito releases being performed on a weekly basis in predefined areas. Two intervention periods (INT1 and INT2) were carried out, with treatment and control areas reversed between INT1 and INT2. Results During INT1, releases in the treated area resulted in up to 91.4% reduction of live progeny of field Ae. aegypti mosquitoes recorded over time, while the control neighborhoods (no releases of sterile male mosquitoes) remained highly infested. The successful implementation of the program during INT1 and INT2 were associated with a 15.9-fold and 13.7-fold lower incidences of dengue in the treated area compared to the control areas, respectively. Conclusions Our data show the success of this new SIT-based program in preventing the spread of dengue.

MATHEMATICAL MODELING OF THE IMPACT OF PERIODIC RELEASE OF STERILE MALE MOSQUITOES AND SEASONALITY ON THE POPULATION ABUNDANCE OF MALARIA MOSQUITOES

2020 ◽  
Vol 28 (02) ◽  
pp. 277-310 ◽  
Author(s):  
ENAHORO A. IBOI ◽  
ABBA B. GUMEL ◽  
JESSE E. TAYLOR
Keyword(s):  
Seasonal Variation ◽  
Mosquito Population ◽  
Local Temperature ◽  
Effective Control ◽  
Population Abundance ◽  
Sterile Male ◽  
Density Dependent ◽  
Malaria Mosquitoes ◽  
The Impact ◽  
Male Mosquitoes

This study presents a new mathematical model for assessing the impact of sterile insect technology (SIT) and seasonal variation in local temperature on the population abundance of malaria mosquitoes in an endemic setting. Simulations of the model, using temperature data from Kipsamoite area of Kenya, show that a peak abundance of the mosquito population is attained in the Kipsamoite area when the mean monthly temperature reaches [Formula: see text]. Furthermore, in the absence of seasonal variation in local temperature, our results show that releasing more sterile male mosquitoes (e.g., 100,000) over a one year period with relatively short duration between releases (e.g., weekly, bi-weekly or even monthly) is more effective than releasing smaller numbers of the sterile male mosquitoes (e.g., 10,000) over the same implementation period and frequency of release. It is also shown that density-dependent larval mortality plays an important role in determining the threshold number of sterile male mosquitoes that need to be released in order to achieve effective control (or elimination) of the mosquito population in the community. In particular, low(high) density-dependent mortality requires high(low) numbers of sterile male mosquitoes to be released to achieve such control. In the presence of seasonal variation in local temperature, effective control of the mosquito population using SIT is only feasible if a large number of the sterile male mosquitoes (e.g., 100,000) is periodically released within a very short time interval (at most weekly). In other words, seasonal variation in temperature necessitates more frequent releases (of a large number) of sterile male mosquitoes to ensure the effectiveness of the SIT intervention in curtailing the targeted mosquito population.

scholarly journals Integrated control of Aedes albopictus in Southwest Germany supported by the Sterile Insect Technique

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Norbert Becker ◽  
Sophie Min Langentepe-Kong ◽  
Artin Tokatlian Rodriguez ◽  
Thin Thin Oo ◽  
Dirk Reichle ◽  
...  
Keyword(s):  
Aedes Albopictus ◽  
Sterile Insect Technique ◽  
Large Scale ◽  
Integrated Control ◽  
Control Program ◽  
Control Area ◽  
West Germany ◽  
Mosquito Vector ◽  
Breeding Sites ◽  
South West

Abstract Background The invasive species Aedes albopictus, commonly known as the Asian tiger mosquito, has undergone extreme range expansion by means of steady introductions as blind passengers in vehicles traveling from the Mediterranean to south-west Germany. The more than 25 established populations in the State of Baden-Württemberg, Palatine and Hesse (south-west Germany) have become a major nuisance and public health threat. Aedes albopictus deserves special attention as a vector of arboviruses, including dengue, chikungunya and Zika viruses. In Germany, Ae. albopictus control programs are implemented by local communities under the auspices of health departments and regulatory offices. Methods The control strategy comprised three pillars: (i) community participation (CP) based on the elimination of breeding sites or improved environmental sanitation, using fizzy tablets based on Bacillus thuringiensis israelensis (fizzy Bti tablets; Culinex® Tab plus); (ii) door-to-door (DtD) control by trained staff through the application of high doses of a water-dispersible Bti granular formulation (Vectobac® WG) aimed at achieving a long-lasting killing effect; and (iii) implementation of the sterile insect technique (SIT) to eliminate remaining Ae. albopictus populations. Prior to initiating large-scale city-wide treatments on a routine basis, the efficacy of the three elements was evaluated in laboratory and semi-field trials. Special emphasis was given to the mass release of sterile Ae. albopictus males. Results More than 60% of the local residents actively participated in the first pillar (CP) of the large-scale control program. The most effective element of the program was found to be the DtD intervention, including the application of Vectobac® WG (3000 ITU/mg) to potential breeding sites (10 g per rainwater container, maximum of 200 l = maximum of approx. 150,000 ITU/l, and 2.5 g per container < 50 l) with a persistence of at least 3 weeks. In Ludwigshafen, larval source management resulted in a Container Index for Ae. albopictus of < 1% in 2020 compared to 10.9% in 2019. The mean number of Aedes eggs per ovitrap per 2 weeks was 4.4 in Ludwigshafen, 18.2 in Metzgergrün (Freiburg) (SIT area) and 22.4 in the control area in Gartenstadt (Freiburg). The strong reduction of the Ae. albopictus population by Bti application was followed by weekly releases of 1013 (Ludwigshafen) and 2320 (Freiburg) sterile Ae. albopictus males per hectare from May until October, resulting in a high percentage of sterile eggs. In the trial areas of Ludwigshafen and Frieburg, egg sterility reached 84.7 ± 12.5% and 62.7 ± 25.8%, respectively; in comparison, the natural sterility in the control area was 14.6 ± 7.3%. The field results were in line with data obtained in cage tests under laboratory conditions where sterility rates were 87.5 ± 9.2% after wild females mated with sterile males; in comparison, the sterility of eggs laid by females mated with unirradiated males was only 3.3 ± 2.8%. The overall egg sterility of about 84% in Ludwigshafen indicates that our goal to almost eradicate the Ae. albopictus population could be achieved. The time for inspection and treatment of a single property ranged from 19 to 26 min depending on the experience of the team and costs 6–8 euros per property. Conclusions It is shown that an integrated control program based on a strict monitoring scheme can be most effective when it comprises three components, namely CP, DtD intervention that includes long-lasting Bti-larviciding to strongly reduce Ae. albopictus populations and SIT to reduce the remaining Ae. albopictus population to a minimum or even to eradicate it. The combined use of Bti and SIT is the most effective and selective tool against Ae. albopictus, one of the most dangerous mosquito vector species. Graphical Abstract

A theoretical study of the invasion of cleared areas by tsetse flies (Diptera: Glossinidae)

2000 ◽  
Vol 90 (3) ◽  
pp. 201-209 ◽  
Author(s):  
J.W. Hargrove
Keyword(s):  
Large Scale ◽  
Theoretical Study ◽  
Mean Square Displacement ◽  
Stochastic Modelling ◽  
Control Area ◽  
Tsetse Flies ◽  
Deterministic Approach ◽  
Community Based ◽  
Treated Area ◽  
Invasion Fronts

Large-scale eradication campaigns against tsetse flies Glossina spp. are giving way to smaller operations aimed at disease and vector containment. There has been little discussion of the effects of these changes in policy. This study estimates the rate at which tsetse re-infect treated areas after the termination of control efforts. Movement is modelled as a diffusion process with a daily root mean square displacement (λ) of 0.2–1 km−1/2 and population growth as logistic with a growth rate (r) ≤1.5% day−1. Invasion fronts move as the product of λ and √r. For r = 0.75% day−1 a front advances at 2.5 km year−1for each 100 m increment in λ. If there are 0.001% survivors in 10% of the treated area, the population recovers to within 1% of the carrying capacity (K) within three years. If the control area is subject to invasion from all sides, a treated block of 10,000 km2 is effectively lost within two years – except at the lowest values of λ and r. Cleared areas of 100 km2 are lost in a year, as observed in a community-based suppression programme in Kenya. If the treated area is closed to re-invasion, but if there is a block where tsetse survive at 0.0001–0.1% of K, the population recovers within 3–4 years for up to 20 km outside the surviving block. If the surviving flies are more widely spread, re-infection is even more rapid. The deterministic approach used here over-estimates re-invasion rates at low density, but comparisons between control scenarios are still valid. Stochastic modelling would estimate more exactly rates of re-infection at near-zero population densities.

The Efficacy of Finlayson Troughs as a Means of Repelling Kangaroos From Water and Altering Grazing Pressure in Pastoral Areas.

1997 ◽  
Vol 19 (1) ◽  
pp. 57 ◽  
Author(s):  
DR King ◽  
GL Norbury ◽  
GJ Eliot
Keyword(s):  
Large Scale ◽  
Grazing Pressure ◽  
Water Sources ◽  
Control Area ◽  
Radio Tracking ◽  
Treated Area ◽  
Macropus Rufus ◽  
Alternative Water ◽  
Alternative Water Sources ◽  
Artificial Water

We attempted to determine whether Finlayson troughs (a selective electric repellent device) would repel kangaroos (Macropus rufus and M. robustus) but still allow sheep to drink when access of kangaroos to artificial water sources was restricted on a large scale, and the effect that had on kangaroo populations. In late 1993 high percentages of kangaroos (over 80% of both species) were repelled from water sources fitted with Finlayson troughs when alternative water sources were available. However, when all water sources within a 100,000 ha area had activated Finlayson troughs or were fenced off, kangaroos found methods that enabled them to circumvent the Finlayson troughs within two weeks after activation of the troughs. The numbers which were able to obtain a drink increased greatly over this period. When used on a large scale, Finlayson troughs as used in this study were thus apparently ineffective in restricting the access of kangaroos to water. Aerial surveys and radio-tracking were used to determine the numbers and distribution of kangaroos over the whole area after activation of all the Finlayson troughs. There were no significant differences in kangaroo numbers between the treated area and a nearby control area which was devoid of Finlayson troughs. All 31 of the radio-collared kangaroos which could be located at the end of the trial remained within the areas they formerly occupied and the length of their movements did not increase.

scholarly journals Modeling the Control of Zika Virus Vector Population Using the Sterile Insect Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
William Atokolo ◽  
Godwin Mbah Christopher Ezike
Keyword(s):  
Equilibrium Point ◽  
Equilibrium Points ◽  
Mosquito Population ◽  
Sterile Male ◽  
Wild Female ◽  
Globally Asymptotically Stable ◽  
Offspring Number ◽  
Vector Population ◽  
Control Intervention ◽  
Male Mosquitoes

This work is aimed at formulating a mathematical model for the control of mosquito population using sterile insect technology (SIT). SIT is an environmental friendly method, which depends on the release of sterile male mosquitoes that compete with wild male mosquitoes and mate with wild female mosquitoes, which leads to the production of no offspring. The basic offspring number of the mosquitoes’ population was computed, after which we investigated the existence of two equilibrium points of the model. When the basic offspring number of the model M0, is less than or equal to 1, a mosquito extinction equilibrium point E2, which is often biologically unattainable, was shown to exits. On the other hand, if M0>1, we have the nonnegative equilibrium point E1 which is shown to be both locally and globally asymptotically stable whenever M0>1. Local sensitivity analysis was then performed to know the parameters that should be targeted by control intervention strategies and result shows that female mating probability to be with the sterile male mosquitoes ρS, mating rate of the sterile mosquito β2, and natural death rates of both aquatic and female mosquitoesμA+μF have greater impacts on the reduction and elimination of mosquitoes from a population. Simulation of the model shows that enough release of sterile male mosquitoes into the population of the wild mosquitoes controls the mosquito population and as such can reduce the spread of mosquito borne disease such as Zika.

Application Optimization for Mosquito Vector Control

2004 ◽  
Author(s):  
Milton E. Teske ◽  
Harold W. Thistle ◽  
Mark Latham ◽  
William H. Reynolds
Keyword(s):  
Vector Control ◽  
Mosquito Vector ◽  
Application Optimization ◽  
Mosquito Vector Control

Pot, atom and step-economic (PASE) synthesis of medicinally relevant spiro[oxindole-3,4′-pyrano[4,3-b]pyran] scaffold

2016 ◽  
Vol 22 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Michail N. Elinson ◽  
Fedor V. Ryzhkov ◽  
Victor A. Korolev ◽  
Mikhail P. Egorov
Keyword(s):  
Multicomponent Reaction ◽  
Multicomponent Reactions ◽  
Large Scale ◽  
Potassium Fluoride ◽  
Environmentally Benign ◽  
Anti Hiv

AbstractFast (3 min) pot, atom and step economics (PASE) potassium fluoride catalyzed multicomponent reaction of isatins, malononitrile and 4-hydroxy-6-methyl-2H-pyran-2-one results in efficient formation of substituted spirooxindole-3,4′-pyrano[4,3-b]pyrans in 92–96% yields. The developed ‘on-solvent’ approach to the substituted spirooxindole-3,4′-pyrano[4,3-b]pyrans – the pharmacologically perspective substances with known antiviral, antileishmanial, anticonvulsant and anti-HIV activities – is beneficial from the viewpoint of diversity-oriented large-scale processes and represents fast and environmentally benign synthetic concept for the multicomponent reactions strategy.

scholarly journals The impact of transfluthrin on the spatial repellency of the primary malaria mosquito vectors in Vietnam: Anopheles dirus and Anopheles minimus

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Nicholas J. Martin ◽  
Vu S. Nam ◽  
Andrew A. Lover ◽  
Tran V. Phong ◽  
Tran C. Tu ◽  
...  
Keyword(s):  
Vector Control ◽  
Large Scale ◽  
Limit Of Detection ◽  
Malaria Vectors ◽  
Adult Mosquito ◽  
Anopheles Dirus ◽  
Anopheles Minimus ◽  
Control Programmes ◽  
The Impact ◽  
Spatial Repellency

Abstract Background The complexity of mosquito-borne diseases poses a major challenge to global health efforts to mitigate their impact on people residing in sub-tropical and tropical regions, to travellers and deployed military personnel. To supplement drug- and vaccine-based disease control programmes, other strategies are urgently needed, including the direct control of disease vectors. Modern vector control research generally focuses on identifying novel active ingredients and/or innovative methods to reduce human-mosquito interactions. These efforts include the evaluation of spatial repellents, which are compounds capable of altering mosquito feeding behaviour without direct contact with the chemical source. Methods This project examined the impact of airborne transfluthrin from impregnated textile materials on two important malaria vectors, Anopheles dirus and Anopheles minimus. Repellency was measured by movement within taxis cages within a semi-field environment at the National Institute of Hygiene and Epidemiology in Hanoi, Vietnam. Knockdown and mortality were measured in adult mosquito bioassay cages. Metered-volume air samples were collected at a sub-set of points in the mosquito exposure trial. Results Significant differences in knockdown/mortality were observed along a gradient from the exposure source with higher rates of knockdown/mortality at 2 m and 4 m when compared with the furthest distance (16 m). Knockdown/mortality was also greater at floor level and 1.5 m when compared to 3 m above the floor. Repellency was not significantly different except when comparing 2 m and 16 m taxis cages. Importantly, the two species reacted differently to transfluthrin, with An. minimus being more susceptible to knockdown and mortality. The measured concentrations of airborne transfluthrin ranged from below the limit of detection to 1.32 ng/L, however there were a limited number of evaluable samples complicating interpretation of these results. Conclusions This study, measuring repellency, knockdown and mortality in two malaria vectors in Vietnam demonstrates that both species are sensitive to airborne transfluthrin. The differences in magnitude of response between the two species requires further study before use in large-scale vector control programmes to delineate how spatial repellency would impact the development of insecticide resistance and the disruption of biting behaviour.

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