sterile insect technique
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2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Norbert Becker ◽  
Sophie Min Langentepe-Kong ◽  
Artin Tokatlian Rodriguez ◽  
Thin Thin Oo ◽  
Dirk Reichle ◽  
...  

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


Insects ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 15
Author(s):  
Eunice Nayeli Martínez-García ◽  
Esteban E. Díaz-González ◽  
Carlos F. Marina ◽  
J. Guillermo Bond ◽  
Jorge J. Rodríguez-Rojas ◽  
...  

Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Sterile Insect Technique (SIT) has been successfully used as part of integrated pest strategies to control populations of insect-plant and livestock pests and is currently being tested as a potential method to reduce mosquito populations in an environmentally friendly approach. However, during the mass rearing steps needed to produce millions of mosquitoes, egg storage and preservation are essential for a certain amount of time. Eggs of Aedes aegypti have a chorionic pad that functions as a sticky substance to glue them onto the inner walls of larval breeding sites. The chorionic pad is chemically made of hyaluronic acid, a hygroscopic compound, responsible to protect them from desiccation over time. Two commercial products with hygroscopic properties, hydrolyzed collagen, and Hyalurosmooth®, both were tested to assess their ability to prolong egg life storage for A. aegypti and A. albopictus. Results showed that 85–95% of Ae. aegypti eggs were able to hatch up to week 8 after being treated with both hydrophilic compounds, compared with the control 66.3%. These two substances showed promising effects for keeping Ae. aegypti eggs viable during prolonged storage in mass rearing insect production focused on vector control SIT programs.


Insects ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 5
Author(s):  
Betzabé Verónica-Murrieta ◽  
José Salvador Meza ◽  
Martha Lucía Baena ◽  
Gerardo Alvarado-Castillo ◽  
Diana Pérez-Staples

Anastrepha ludens (Diptera: Tephritidae), is a damaging agricultural pest. Currently, the Sterile Insect Technique (SIT) is used as part of its control. The SIT consists of the mass-rearing, sterilization, and release of insects in target areas. Sterile males mate with wild females, and prevent them from laying fertile eggs. However, even if females mate with sterile males, they can then remate with a second male. If this second male is wild, then this could reduce the efficiency of the SIT by producing viable offspring. The amount of progeny produced by second males (P2 values) for A. ludens is unknown. Here, we evaluated the biological attributes, mating competitiveness, and the proportion of male paternity gained by the second male, using strains that carry fluorescent marker genes and can be potentially used to develop transgenic sexing strains. Furthermore, the transgenic strains were irradiated, to test their ability to induce sterility in females. We found that the 443-G strain had significantly higher larval survival than the 419-R strain. No significant difference was found between the two strains in their mating probability with wild females. We found P2 values between 67 and 74% for the 419-R and the 443-G strain, respectively. Second male sperm precedence only decreased slightly after 12 days, suggesting that sperm from the first and second male is not mixing with time, but rather the second male’s sperm prevails. Furthermore, sterile 443-G males induced significantly higher sterility in females than sterile males from the 419-R strain. The apparent lower ability of the 443-G strain to inhibit female remating should be further investigated. Knowledge of the pre and postcopulatory performance of transgenic strains will help in understanding their potential for control.


2021 ◽  
pp. 1-20
Author(s):  
Liming Cai ◽  
Lanjing Bao ◽  
Logan Rose ◽  
Jeffery Summers ◽  
Wandi Ding

Author(s):  
Beni Ernawan ◽  
Tjandra Anggraeni ◽  
Sri Yusmalinar ◽  
Intan Ahmad

Abstract The sterilization process using gamma irradiation is a crucial component in a program using sterile insect technique (SIT) to control Aedes aegypti. Unfortunately, there is no efficient standard protocol for sterilizing mosquitoes that can produce a high level of sterility while maintaining mating ability and longevity. Therefore, we conducted a study of the critical factors necessary to develop such a standard protocol. In this study, male Ae. aegypti pupae, as well as adults aged 1 d and 3 d, were irradiated using a Gamma-cell 220 irradiator doses of 0, 20, 40, 60, 70, 80, and 100 Gray (Gy). In addition, male Ae. aegypti in the pupal and adult stage aged 1 d were irradiated at a dose of 70 Gy at various temperatures. Changes in emergence rates, longevity, sterility, and mating competitiveness were recorded for each combination of parameters. Results showed that an increase of irradiation dose leads to a rise of induced sterility at all developmental stages, while simultaneously reducing emergence rate, survival, and mating competitiveness. Higher temperatures resulted in increased levels of sterility, reduced longevity, and did not affect the ability to mate. This study found that an irradiation dose of 70 Gy at a temperature between 20.00 and 22.30°C administered in the pupal stage induced a high level of sterility (around 98%), while maintaining mating competitiveness and longevity.


2021 ◽  
Author(s):  
Norbert Becker ◽  
Sophie Min Langentepe-Kong ◽  
Artin Tokatlian Rodriguez ◽  
Thin Thin Oo ◽  
Dirk Reichle ◽  
...  

Abstract BackgroundThe invasive species Aedes albopictus, the Asian tiger mosquito, has undergone an extreme expansion by steady introductions as blind passengers in vehicles from the Mediterranean to South-West Germany. The more than 15 established populations in the State of Baden-Württemberg and Palatine (South-West Germany) have become a major nuisance and public health threat. Aedes albopictus deserves special attention as vector of arboviruses like dengue, chikungunya or Zika virus. In Germany, control of Ae. albopictus is implemented under the auspice of health departments and regulatory offices. MethodsThe control strategy comprised three components or pillars: a) community participation (CP) based on the elimination or sanitation of breeding sites with the use of fizzy Bti-tablets (Culinex Tab plus); b) Door-to-Door (DtD) control by trained staff applying high doses of a Bti-water-dispersible granular formulation (Vectobac WG) aimed for a long-lasting killing effect; and c) the Sterile Insect Technique (SIT) to eliminate remaining Ae. albopictus populations. Prior to large scale routine city-wide treatments, the efficacy of the three elements was evaluated in laboratory and semi-field trials. Special emphasis was given to the mass release of Ae. albopictus sterile males.ResultsMore than 60% of the local residents joined the Community Participation within the large-scale control program. It was shown that the most effective element was the DtD intervention including the application of Vectobac WG (2700 ITU/mg after radiation with 25 kGy) to potential breeding sites (10 g/rainwater container, max. 200L ≙ 13,500ITU/L and 2.5g/container <50L) with a persistence of at least about three weeks. The average time required for the inspection and treatment per property was 27 minutes. In Ludwigshafen the larval source management resulted in a container index for Ae. albopictus below 1% in 2020 compared to 10.9% in 2019. The mean number of Aedes eggs/ovitrap were 4.3 in Ludwigshafen and 18.23 in Freiburg-Metzgergrün (SIT areas); while 22.4 in Freiburg-Gartenstadt (Control area). After the strong reduction of the Aedes population by Bti-application, the weekly release of 1,013 (Ludwigshafen) and 2,320 (Freiburg) sterile Ae. albopictus males/ha from May until October resulted in a high percentage of sterile eggs. In the trial area of Ludwigshafen the sterility of eggs reached 82.61% (mean: 60.52%; SD: 42.88%) and in Freiburg 62.68% (SD 28.21%). The natural sterility in the control area was 16.93±13.5%. The field results were in line with data obtained in cage tests under laboratory conditions where wild females mated with sterile males showed sterility rates of 87.53±9.15%. The sterility of eggs laid by females mated with unirradiated males was only 3.3±2.8%. The overall sterility of about 83% in Ludwigshafen indicates that our goal to almost eradicate the Ae. albopictus population could be achieved. ConclusionsIt is shown that an integrated control program based on a strict monitoring scheme is most effective when it comprises three components, namely a) community participation, b) DtD intervention including long-lasting Bti-larviciding to strongly reduce Ae. albopictus populations and c) the release of sterile males to reduce the remaining Ae. albopictus population to a minimum or even to eradicate it. The combination of the use of Bti with SIT are most effective and selective tools against Ae. albopictus, one of the most dangerous mosquito vector species.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ming Li ◽  
Ting Yang ◽  
Michelle Bui ◽  
Stephanie Gamez ◽  
Tyler Wise ◽  
...  

AbstractThe mosquito Aedes aegypti is the principal vector for arboviruses including dengue/yellow fever, chikungunya, and Zika virus, infecting hundreds of millions of people annually. Unfortunately, traditional control methodologies are insufficient, so innovative control methods are needed. To complement existing measures, here we develop a molecular genetic control system termed precision-guided sterile insect technique (pgSIT) in Aedes aegypti. PgSIT uses a simple CRISPR-based approach to generate flightless females and sterile males that are deployable at any life stage. Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, suppress, and even eliminate mosquito populations. This platform technology could be used in the field, and adapted to many vectors, for controlling wild populations to curtail disease in a safe, confinable, and reversible manner.


PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257097
Author(s):  
Meriem Msaad Guerfali ◽  
Kamel Charaabi ◽  
Haytham Hamden ◽  
Wafa Djobbi ◽  
Salma Fadhl ◽  
...  

Ceratitis capitata (medfly) is one of the most devastating crop pests worldwide. The Sterile Insect Technique (SIT) is a control method that is based on the mass rearing of males, their sterilization, and release in the field. However, the effectiveness of the technique depends on the quality of the released males and their fitness. We previously isolated and selected a probiotic bacteria (Enterobacter sp.), from wild-caught medflies, according to criteria that improved biological quality traits of reared medfly males.We firstly evaluated the impact of the irradiation on the expression of different immune and stress genes in the medfly sterile males. Expression was measured at differents time points ranging from 0 to 168 h after irradiation to capture the response of genes with distinct temporal expression patterns. Then, we supplemented the larval diet with previously isolated Enterobacter sp.strain, live and autoclaved at various concentrations to see whether the probiotic treatments affect, through their protective role, the gene expression level, and quality traits. The irradiation had significant effect on the genes attacin, cecropin, PGPR-LC, hsp23, and hsp70 level expression. The expression of attacin and PGPR-LC was up-regulated while that of cecropin was down-regulated. Hsp genes showed decreased levels between 0 and 18 h to peak at 72 h. However, the supplementation of the probiotic strain, either live or autoclaved, was statistically significant only for attacingene. However, significant interaction time x probiotic was noticed for attacin, cecropin, hsp23 and hsp70. The probiotic treatments also improved the quality control parameters like pupal weight. From this work we can conclude that a consortium of parabiotics (autoclaved probiotics) treatment will be recommended in insectaries considering both the beneficial effects on mass reared insects and its general safety for insectary workers and for environment.


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