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1.
PLoS Negl Trop Dis ; 14(3): e0008047, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32187187

RESUMO

Since Zika virus (ZIKV) emerged as a global human health threat, numerous studies have pointed to Aedes aegypti as the primary vector due to its high competence and propensity to feed on humans. The majority of vector competence studies have been conducted between 26-28°C, but arboviral extrinsic incubation periods (EIPs), and therefore transmission efficiency, are known to be affected strongly by temperature. To better understand the relationship between ZIKV EIPs and temperature, we evaluated the effect of adult mosquito exposure temperature on ZIKV infection, dissemination, and transmission in Ae. aegypti at four temperatures: 18°C, 21°C, 26°C, and 30°C. Mosquitoes were exposed to viremic mice infected with a 2015 Puerto Rican ZIKV strain, and engorged mosquitoes were sorted into the four temperatures with 80% RH and constant access to 10% sucrose. ZIKV infection, dissemination, and transmission rates were assessed via RT-qPCR from individual mosquito bodies, legs and wings, and saliva, respectively, at three to five time points per temperature from three to 31 days, based on expectations from other flavivirus EIPs. The median time from ZIKV ingestion to transmission (median EIP, EIP50) at each temperature was estimated by fitting a generalized linear mixed model for each temperature. EIP50 ranged from 5.1 days at 30°C to 24.2 days at 21°C. At 26°C, EIP50 was 9.6 days. At 18°C, only 15% transmitted by day 31 so EIP50 could not be estimated. This is among the first studies to characterize the effects of temperature on ZIKV EIP in Ae. aegypti, and the first to do so based on feeding of mosquitoes on a live, viremic host. This information is critical for modeling ZIKV transmission dynamics to understand geographic and seasonal limits of ZIKV risk; it is especially relevant for determining risk in subtropical regions with established Ae. aegypti populations and relatively high rates of return travel from the tropics (e.g. California or Florida), as these regions typically experience cooler temperature ranges than tropical regions.


Assuntos
Aedes/efeitos da radiação , Aedes/virologia , Exposição Ambiental , Mosquitos Vetores/efeitos da radiação , Mosquitos Vetores/virologia , Temperatura , Zika virus/crescimento & desenvolvimento , Estruturas Animais/virologia , Animais , Modelos Animais de Doenças , Transmissão de Doença Infecciosa , Feminino , Camundongos , Modelos Estatísticos , RNA Viral/análise , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo , Infecção por Zika virus/transmissão
2.
PLoS Negl Trop Dis ; 13(10): e0007771, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31658265

RESUMO

BACKGROUND: Important arboviral diseases, such as dengue, chikungunya, and Zika virus infections, are transmitted mainly by the Aedes aegypti vector. So far, controlling this vector species with current tools and strategies has not demonstrated sustainable and significant impacts. Our main objective was to evaluate whether open field release of sterile males, produced from combining the sterile insect technique using radiation with the insect incompatible technique through Wolbachia-induced incompatibility (SIT/IIT), could suppress natural populations of Ae. aegypti in semi-rural village settings in Thailand. METHODOLOGY/PRINCIPAL FINDINGS: Irradiated Wolbachia-infected Aedes aegypti males produced by the SIT/IIT approach were completely sterile and were able to compete with the wild fertile ones. Open field release of these sterile males was conducted in an ecologically isolated village in Chachoengsao Province, eastern Thailand. House-to-house visit and media reports resulted in community acceptance and public awareness of the technology. During intervention, approximately 100-200 sterile males were released weekly in each household. After 6 months of sterile male release, a significant reduction (p<0.05) of the mean egg hatch rate (84%) and the mean number of females per household (97.30%) was achieved in the treatment areas when compared to the control ones. CONCLUSIONS/SIGNIFICANCE: Our study represents the first open field release of sterile Ae. aegypti males developed from a combined SIT/IIT approach. Entomological assessment using ovitraps, adult sticky traps, and portable vacuum aspirators confirmed the success in reducing natural populations of Ae. aegypti females in treated areas. Public awareness through media resulted in positive support for practical use of this strategy in wider areas. Further study using a systematic randomized trial is needed to determine whether this approach could have a significant impact on the diseases transmitted by Ae. aegypti vector.


Assuntos
Aedes/fisiologia , Entomologia/métodos , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , População Rural , Aedes/microbiologia , Aedes/efeitos da radiação , Animais , Feminino , Humanos , Infertilidade Masculina , Masculino , Mosquitos Vetores/microbiologia , Mosquitos Vetores/efeitos da radiação , Dinâmica Populacional , Caracteres Sexuais , Tailândia , Wolbachia/genética , Wolbachia/fisiologia
3.
Parasit Vectors ; 12(1): 435, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31500662

RESUMO

BACKGROUND: The sterile insect technique (SIT) for use against mosquitoes consists of several steps including the production of the target species in large numbers, the separation of males and females, the sterilization of the males, and the packing, transport and release of the sterile males at the target site. The sterility of the males is the basis of the technique; for this, efficient and standardized irradiation methods are needed to ensure that the required level of sterility is reliably and reproducibly achieved. While several reports have found that certain biological factors, handling methods and varying irradiation procedures can alter the level of induced sterility in insects, few studies exist in which the methodologies are adequately described and discussed for the reproductive sterilization of mosquitoes. Numerous irradiation studies on mosquito pupae have resulted in varying levels of sterility. Therefore, we initiated a series of small-scale experiments to first investigate variable parameters that may influence dose-response in mosquito pupae, and secondly, identify those factors that potentially have a significantly large effect and need further attention. METHODS: In this study, we compiled the results of a series of experiments investigating variable parameters such as pupal age (Aedes aegypti), pupal size (Ae. aegypti), geographical origin of mosquito strains (Ae. aegypti and Ae. albopictus), exposure methods (in wet versus dry conditions, Ae. albopictus) and subsequently in low versus high oxygen environments [submerged in water (low O2 (< 5 %)] and in air [high O2 (~ 21 %)] on the radiosensitivity of male pupae (Ae. aegypti, Ae. albopictus and Anopheles arabiensis). RESULTS: Results indicate that radiosensitvity of Ae. aegypti decreases with increasing pupal age (99% induced sterility in youngest pupae, compared to 93% in oldest pupae), but does not change with differences in pupal size (P = 0.94). Differing geographical origin of the same mosquito species did not result in variations in radiosensitivity in Ae. aegypti pupae [Brazil, Indonesia, France (La Reunion), Thailand] or Ae. albopictus [Italy, France (La Reunion)]. Differences in induced sterility were seen following irradiation of pupae that were in wet versus dry conditions, which led to further tests showing significant radioprotective effects of oxygen depletion during irradiation procedures in three tested mosquito species, as seen in other insects. CONCLUSIONS: These findings infer the necessity to further evaluate significant factors and reassess dose-response for mosquitoes with controlled variables to be able to formulate protocols to achieve reliable and reproducible levels of sterility for application in the frame of the SIT.


Assuntos
Aedes/efeitos da radiação , Anopheles/efeitos da radiação , Mosquitos Vetores/efeitos da radiação , Pupa/efeitos da radiação , Tolerância a Radiação , Irradiação Corporal Total/normas , Animais , Entomologia/normas , Masculino
4.
Acta Trop ; 199: 105110, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31351072

RESUMO

Aedes albopictus is a vector of several human viral diseases, including dengue, chikungunya, and Zika. New control method for Aedes albopictus is needed to replace traditional methods such as chemical insecticides which induce resistance, environmental contamination and toxicity to human. In sterile insect technique (SIT), male mosquitoes are sterilized by γ-ray or X-ray irradiation before released. In this study, the relative effectiveness of X-ray irradiation as a mosquito SIT was investigated. Both pupal and adult Aedes albopictus were subjected to different radiation doses and their emergence, survivorship, longevity, induced sterility, and male mating competitiveness were evaluated. Relative to controls, irradiation had no significant effect on emergence and survivorship but significantly reduce adult longevity. Induced sterility were essentially same for both irradiated pupal and adult. At a dose of 40 Gy, 97% and 100% sterility was respectively achieved for males and females. Mating competitiveness was reduced both in adult males and those derived from pupae exposed to 40 Gy. However, populations can be suppressed by increasing the release ratio (sterile: normal). When the release ratio was 7:1, 74% of the wild population could be suppressed. Overall, the results of the present study showed that SIT based on X-Ray irradiation is scientific and feasible to control Aedes albopictus.


Assuntos
Aedes/efeitos da radiação , Infertilidade , Controle de Mosquitos/métodos , Animais , Feminino , Masculino , Pupa/efeitos da radiação , Raios X
5.
PLoS One ; 14(2): e0212520, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30779779

RESUMO

The sterile insect technique (SIT) may offer a means to control the transmission of mosquito borne diseases. SIT involves the release of male insects that have been sterilized by exposure to ionizing radiation. We determined the effects of different doses of radiation on the survival and reproductive capacity of local strains of Aedes aegypti and Ae. albopictus in southern Mexico. The survival of irradiated pupae was invariably greater than 90% and did not differ significantly in either sex for either species. Irradiation had no significant adverse effects on the flight ability (capacity to fly out of a test device) of male mosquitoes, which consistently exceeded 91% in Ae. aegypti and 96% in Ae. albopictus. The average number of eggs laid per female was significantly reduced in Ae. aegypti at doses of 15 and 30 Gy and no eggs were laid by females that had been exposed to 50 Gy. Similarly, in Ae. albopictus, egg production was reduced at doses of 15 and 25 Gy and was eliminated at 35 Gy. In Ae. aegypti, fertility in males was eliminated at 70 Gy and was eliminated at 30 Gy in females, whereas in Ae. albopictus, the fertility of males that mated with untreated females was almost zero (0.1%) in the 50 Gy treatment and female fertility was eliminated at 35 Gy. Irradiation treatments resulted in reduced ovary length and fewer follicles in both species. The adult median survival time of both species was reduced by irradiation in a dose-dependent manner. However, sterilizing doses of 35 Gy and 50 Gy resulted in little reduction in survival times of males of Ae. albopictus and Ae. aegypti, respectively, indicating that these doses should be suitable for future evaluations of SIT-based control of these species. The results of the present study will be applied to studies of male sexual competitiveness and to stepwise evaluations of the sterile insect technique for population suppression of these vectors in Mexico.


Assuntos
Aedes/efeitos da radiação , Fertilidade/efeitos da radiação , Controle de Mosquitos/métodos , Animais , Infertilidade , Insetos , Masculino , México , Mosquitos Vetores , Doses de Radiação , Radiação Ionizante , Dosagem Radioterapêutica , Comportamento Sexual Animal/efeitos da radiação , Esterilização Reprodutiva/métodos
6.
Parasit Vectors ; 11(Suppl 2): 657, 2018 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-30583749

RESUMO

BACKGROUND: The sterile insect technique (SIT), which is based on irradiation-induced sterility, and incompatible insect technique (IIT), which is based on Wolbachia-induced cytoplasmic incompatibility (a kind of male sterility), have been used as alternative methods to reduce mosquito vector populations. Both methods require the release of males to reduce fertile females and suppress the number of natural populations. Different techniques of sex separation to obtain only males have been investigated previously. Our work involves an application of mechanical larval-pupal glass separators to separate Wolbachia-infected Aedes aegypti males from females at the pupal stage, prior to irradiation, and for use in a pilot field release and to assess the quality of males and females before and after sex separation and sterilization. RESULTS: This study was the first to demonstrate the efficiency of mechanical glass separators in separating males for use in an Ae. aegypti suppression trial by a combined SIT/IIT approach. Our results indicated that male and female pupae of Wolbachia-infected Ae. aegypti mosquitoes were significantly different (p < 0.05) in weight, size, and emergence-time, which made it easier for sex separation by this mechanical method. During the pilot field release, the percentage of female contamination was detected to be quite low and significantly different between the first (0.10 ± 0.13) and the second (0.02 ± 0.02) twelve-week period. Both males and females were almost completely sterile after exposure to 70 Gy irradiation dose. We observed that both irradiated Wolbachia-infected males and females survived and lived longer than two weeks, but males could live longer than females (p < 0.05) when they were irradiated at the same irradiation dose. When comparing irradiated mosquitoes with non-irradiated ones, there was no significant difference in longevity and survival-rate between those males, but non-irradiated females lived longer than irradiated ones (p < 0.05). CONCLUSION: Mechanical sex separation by using a larval-pupal glass separator was practically applied to obtain only males for further sterilization and open field release in a pilot population suppression trial of Ae. aegypti in Thailand. Female contamination was detected to be quite low, and skilled personnel can reduce the risk for female release. The irradiated Wolbachia-infected females accidentally released were found to be completely sterile, with shorter life span than males.


Assuntos
Aedes/fisiologia , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Wolbachia/fisiologia , Aedes/microbiologia , Aedes/efeitos da radiação , Animais , Feminino , Infertilidade Masculina , Longevidade , Masculino , Mosquitos Vetores/microbiologia , Mosquitos Vetores/efeitos da radiação , Projetos Piloto , Controle da População , Pupa , Caracteres Sexuais , Análise para Determinação do Sexo , Tailândia
7.
Parasit Vectors ; 11(1): 603, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30463624

RESUMO

BACKGROUND: To ensure the success of a mosquito control programme that integrates the sterile insect technique (SIT), it is highly desirable to release sterile males with a maximal lifespan to increase release effectiveness. Understanding sterile male survival under field conditions is thus critical for determining the number of males to be released. Our study aimed to investigate the effect of mass rearing, irradiation, chilling, packing and release time on irradiated male mosquito longevity. METHODS: Anopheles arabiensis and Aedes aegypti immature stages were mass-reared using a rack and tray system. Batches of 50 males irradiated at the pupal stage were immobilised, packed into canisters and chilled for 6 hours at 6 °C. Mosquitoes were then transferred either in the early morning or early evening into climate chambers set to simulate the weather conditions, typical of the beginning of the rainy season in Khartoum, Sudan and Juazeiro, Brazil for An. arabiensis and Ae. aegypti, respectively. The longevity of experimental males was assessed and compared to mass-reared control males subjected either to simulated field or laboratory conditions. RESULTS: The combined irradiation, chilling and packing treatments significantly reduced the longevity of both An. arabiensis and Ae. aegypti under simulated field conditions (P < 0.001). However, packing alone did not significantly reduce longevity of Ae. aegypti (P = 0.38) but did in An. arabiensis (P < 0.001). Overall, the longevity of mass reared, irradiated and packed males was significantly reduced, with the median survival time (days) lower following an early morning introduction (4.62 ± 0.20) compared to an evening (7.34 ± 0.35) in An. arabiensis (P < 0.001). However, there was no significant difference in longevity between morning (9.07 ± 0.54) and evening (7.76 ± 0.50) in Ae. aegypti (P = 0.14). CONCLUSIONS: Our study showed that sterile mass-reared males have a reduced lifespan in comparison to laboratory-maintained controls under simulated field conditions, and that An. arabiensis appeared to be more sensitive to the handling process and release time than Ae. aegypti. Longevity and release time are important parameters to be considered for a successful area-wide integrated vector control programme with a SIT component.


Assuntos
Aedes/efeitos da radiação , Anopheles/efeitos da radiação , Longevidade , Aedes/crescimento & desenvolvimento , Aedes/fisiologia , Animais , Anopheles/crescimento & desenvolvimento , Anopheles/fisiologia , Clima , Entomologia/instrumentação , Entomologia/métodos , Umidade , Infertilidade , Masculino , Pupa/efeitos da radiação , Temperatura
8.
PLoS One ; 13(8): e0202236, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30107004

RESUMO

The control of Aedes albopictus through Sterile Male Releases requires that the most competitive males be mass-reared and sterilized usually with gamma- or X-ray radiation prior to release. Developing an understanding of the impact of irradiation treatment on flight performance in sterile males is very important because any fitness cost may reduce the efficacy of SIT intervention in the field. Here, we examined the role of irradiation exposure and sugar-feeding on daily flight activity and performance of Ae. albopictus males sterilized during pupal stage with gamma-radiation at 35Gray from a Caesium 137 source. We used a previously developed automated video tracking system to monitor the flight activity of different groups of sterile and control non-sterile males over 24 hours in a flight arena. This monitoring took place under controlled laboratory conditions and we wished to quantify the daily flight activity and to highlight any changes due to radiation treatment and nutritional conditions (starved versus sugar fed). Our experimental evidence demonstrated a characteristic diurnal flight activity with a bimodal pattern regardless of the treatment. Precisely, both irradiated and non-irradiated males exhibited two distinct peaks in flight activity in the morning (6-8 a.m.) and late afternoon (4-6 p.m.). Under changing physiological conditions, irradiated males were generally more active over time and flew longer overall distances than control male populations. These results suggest some internal circadian control of the phase relation to the light-dark cycle, with evidence for modification of flight performance by nutritional status. The fact that daily activity patterns are alike in irradiated and control Ae. albopictus males, and that sterile males could display higher flight performance, is in contrast with the hypothesis that irradiation treatment appears to reduce the fitness of male mosquitoes. We discuss the implications of the present study in sterile-male release programs against Ae. albopictus.


Assuntos
Aedes/fisiologia , Aedes/efeitos da radiação , Voo Animal/efeitos da radiação , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/efeitos da radiação , Aedes/virologia , Animais , Radioisótopos de Césio , Ritmo Circadiano , Relação Dose-Resposta à Radiação , Fertilidade/efeitos da radiação , Raios gama , Humanos , Masculino , Mosquitos Vetores/virologia , Pupa/efeitos da radiação
9.
Pathog Glob Health ; 112(3): 107-114, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29737236

RESUMO

Arthropod-borne disease outbreaks, facilitated by the introduction of exotic mosquitoes, pose a significant public health threat. Recent chikungunya virus (CHIKV) epidemics in Europe highlight the importance of understanding the vector potential of invading mosquitoes. In this paper we explore the potential of Aedes koreicus, a mosquito new to Europe, to transmit CHIKV. Mosquitoes were challenged with CHIKV and maintained at two temperatures: 23 °C and a fluctuating temperature. Total CHIKV infection rates at 3, 10 and 14 days post-feeding were low for both temperature treatments (13.8% at 23 °C; 6.2% at fluctuating T). A low percentage (6.1%, n = 65) of mosquitoes maintained at a constant 23 °C showed dissemination of the virus to the wings and legs. Infection of mosquito saliva, with live virus, occurred in 2 mosquitoes. No dissemination was noted under the fluctuating temperature regime. Based on these results we conclude that CHIKV transmission by this species is possible.


Assuntos
Aedes/crescimento & desenvolvimento , Aedes/virologia , Febre de Chikungunya/transmissão , Vírus Chikungunya/isolamento & purificação , Mosquitos Vetores/crescimento & desenvolvimento , Mosquitos Vetores/virologia , Aedes/classificação , Aedes/efeitos da radiação , Animais , Transmissão de Doença Infecciosa , Europa (Continente) , Extremidades/virologia , Mosquitos Vetores/efeitos da radiação , Saliva/virologia , Temperatura , Asas de Animais/virologia
10.
Parasit Vectors ; 11(1): 212, 2018 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-29587850

RESUMO

BACKGROUND: In Switzerland, the invasive Asian tiger mosquito, Aedes albopictus, is firmly established in the Canton of Ticino, south of the Alps. According to a large-scale distribution model developed in 2013, suitable climatic conditions for the establishment of Ae. albopictus north of the Alps are found in Basel and Geneva while Zurich appears to be characterized by winters currently being too cold for survival of diapausing eggs. However, the spatial resolution of large-scale distribution models might not be sufficient to detect particular climatic conditions existing in urban settings, such as the presence of microclimatic temperatures, which may positively influence the probability of diapausing eggs to overwinter. In order to investigate this, microclimatic monitoring of potential diapausing sites (i.e. catch basins) and external controls was performed in January 2017 in Ticino and within the cities of Basel, Geneva and Zurich. RESULTS: Mean January temperatures in catch basins of Basel, Geneva and Zurich were always higher than the -1 °C temperature threshold previously set for survival probability of diapausing eggs, while mean January temperatures were below -1 °C in several catch basins south of the Alps, where Ae. albopictus eggs currently overwinter. The catch basin absolute January daily minimum temperatures both south and north of the Alps were in general higher than the external control temperatures. Absolute January daily minimum temperatures in catch basins in Basel, Geneva and Zurich were always above -10 °C, indicating that diapausing Ae. albopictus eggs could potentially survive winter nights in urban areas north of the Alps. CONCLUSIONS: The findings confirmed previous conclusions that urban catch basins can provide favourable conditions for overwintering of diapausing eggs compared to more cold-exposed sites. The results confirmed the presence of suitable winter conditions for the establishment of Ae. albopictus in the cities of Basel and Geneva. In addition, the microclimate-scale analysis added new information compared to the previous large-scale prevision model by showing that also the city of Zurich could provide winter conditions suitable for the establishment of Ae. albopictus. This illustrates the importance of the resolution of climate data in using models to predict Ae. albopictus distribution.


Assuntos
Aedes/fisiologia , Aedes/efeitos da radiação , Diapausa de Inseto/efeitos da radiação , Ecossistema , Zigoto/fisiologia , Zigoto/efeitos da radiação , Animais , Cidades , Suíça , Temperatura
11.
Parasit Vectors ; 11(1): 22, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29310716

RESUMO

BACKGROUND: Taiwan is geographically located in a region that spans both tropical and subtropical climates (22-25°N and 120-122°E). The Taiwan Centers for Disease Control have found that the ecological habitat of Aedes aegypti appears only south of 23.5°N. Low temperatures may contribute to this particular habitat distribution of Ae. aegypti under the influence of the East Asian winter monsoon. However, the threshold condition related to critically low temperatures remains unclear because of the lack of large-scale spatial studies. This topic warrants further study, particularly through national entomological surveillance and satellite-derived land surface temperature (LST) data. METHODS: We hypothesized that the distribution of Ae. aegypti is highly correlated with the threshold nighttime LST and that a critical low LST limits the survival of Ae. aegypti. A mosquito dataset collected from the Taiwan Centers for Disease Control was utilized in conjunction with image data obtained from the moderate resolution imaging spectroradiometer (MODIS) during 2009-2011. Spatial interpolation and phi coefficient methods were used to analyze the correlation between the distributions of immature forms of Ae. aegypti and threshold LST, which was predicted from MODIS calculations for 348 townships in Taiwan. RESULTS: According to the evaluation of the correlation between estimated nighttime temperatures and the occurrence of Ae. aegypti, winter had the highest peak phi coefficient, and the corresponding estimated threshold temperatures ranged from 13.7 to 14 °C in the ordinary kriging model, which was the optimal interpolation model in terms of the root mean square error. The mean threshold temperature was determined to be 13.8 °C, which is a critical temperature to limit the occurrence of Ae. aegypti. CONCLUSIONS: An LST of 13.8 °C was found to be the critical temperature for Ae. aegypti larvae, which results in the near disappearance of Ae. aegypti during winter in the subtropical regions of Taiwan under the influence of the prevailing East Asian winter monsoon.


Assuntos
Aedes/fisiologia , Aedes/efeitos da radiação , Temperatura Baixa , Exposição Ambiental , Animais , Bioestatística , Entomologia/métodos , Larva/fisiologia , Larva/efeitos da radiação , Análise de Sobrevida , Taiwan
12.
Toxicol Ind Health ; 33(12): 930-937, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28992792

RESUMO

The study was undertaken to evaluate gamma radiation-induced DNA damage in Aedes aegypti. The comet assay was employed to demonstrate the extent of DNA damage produced in adult male A. aegypti exposed to seven different doses of gamma radiation, ranging from 1 Gy to 50 Gy. DNA damage was measured as the percentage of comet tail DNA. A significant linear increase in DNA damage was observed in all samples; the extent of damage being proportional to the dose of gamma radiation the organism received, except in those treated with 1 Gy. The highest amount of DNA damage was noticed at 1 h postirradiation, which decreased gradually with time, that is, at 3, 6 and 12 h postirradiation. This may indicate repair of the damaged DNA and/or loss of heavily damaged cells as the postirradiation time increased. The comet assay serves as a sensitive and rapid technique to detect gamma radiation-induced DNA damage in A. aegypti. This could be used as a potential biomarker for environmental risk assessment.


Assuntos
Aedes/genética , Aedes/efeitos da radiação , Dano ao DNA/efeitos da radiação , Raios gama/efeitos adversos , Animais , Ensaio Cometa , DNA/genética , Relação Dose-Resposta à Radiação , Masculino , Testes de Mutagenicidade
13.
PLoS Negl Trop Dis ; 11(9): e0005881, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28892483

RESUMO

The capacity of the released sterile males to survive, disperse, compete with wild males and inseminate wild females is an essential prerequisite to be evaluated in any area-wide integrated pest management (AW-IPM) programs including a sterile insect release method. Adequate quality control tests supported by standardized procedures need to be developed to measure these parameters and to identify and correct potential inappropriate rearing or handling methods affecting the overall male quality. In this study, we report results on the creation and validation of the first quality control devices designed to infer the survival and mating capacity of radio-sterilized Aedes albopictus males through the observation of their flight capacity under restricted conditions (flight organ device) and after stress treatment (aspirator device). Results obtained consistently indicate comparable flight capacity and quality parameters between untreated and 35 Gy irradiated males while a negative impact was observed with higher radiation doses at all observation time performed. The male flight capacity registered with the proposed quality control devices can be successfully employed, with different predictive capacities and response time, to infer the adult male quality. These simple and cost-effective tools provide a valuable method to detect and amend potentially sub-standard procedures in the sterile male production line and hence contribute to maintaining optimal quality and field performance of the mosquitoes being released.


Assuntos
Aedes/fisiologia , Controle Biológico de Vetores/normas , Aedes/efeitos da radiação , Animais , Voo Animal/efeitos da radiação , Masculino , Controle Biológico de Vetores/economia , Controle Biológico de Vetores/métodos , Pupa/efeitos da radiação , Controle de Qualidade , Comportamento Sexual Animal
14.
PLoS One ; 12(6): e0178766, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28582398

RESUMO

There are many products claiming to be an electronic solution towards repelling mosquitoes. Several reviews were published in debunking these claims. However, there is a lack of a systematic study on effects of electromagnetic (EM) or more specifically, radio frequency (RF) waves against mosquitoes due to the conclusions made in those years. Therefore, we attempt to establish a fundamental study on female Aedes Aegypti (Linnaeus) mosquitoes by quantifying the collective behavior of the mosquitoes against a continuous stream of low-powered RF signals via a broadband horn antenna using image processing methods. By examining the average lateral and vertical positions of the mosquitoes versus frequency and time, the data shows negligible consistency in the reactions of the mosquitoes toward the different frequencies ranging from 10 to 20,000.00 MHz, with a step of 10 MHz. This was done by examining 33 hours of spatiotemporal data, which was divided into three sessions. All three sessions showed totally different convolutions in the positions in arbitrary units based on the raster scan of the image processing output. Several frequencies apparently showed up to 0.2-70% shift in both lateral and vertical components along the spectrum, without repeatability for all three sessions. This study contributes to the following: A pilot study for establishing the collective effects of RF against mosquitoes, open-source use, and finally a low-cost and easily adaptable platform for the study of EM effects against any insects.


Assuntos
Aedes/fisiologia , Comportamento Animal/fisiologia , Aedes/efeitos da radiação , Animais , Comportamento Animal/efeitos da radiação , Feminino , Controle de Mosquitos/instrumentação , Projetos Piloto , Ondas de Rádio
15.
Sci Rep ; 7: 42058, 2017 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-28169356

RESUMO

Phytoalexins phenalenones (PNs) are phytochemicals biosynthesized inside the plant in responsive to exterior threat. PNs are excellent type-II photosensitizers, which efficiently produce singlet oxygen upon light irradiation. Based on the core functional structure of PNs, novel PN derivatives were synthesized here and their singlet oxygen generating abilities and their phototoxicity were evaluated. At the presence of light, these PNs have photoinduced toxicity towards Aedes albopictus larvae and nematode Meloidogyne incognita, while the activity lost in the dark. The obvious tissue damage was observed on the treated mosquito larvae and nematode due to the generation of singlet oxygen. Our results revealed the potential of phenalenones as photoactivated agents for mosquito and root-knot nematode management together with light.


Assuntos
Aedes/efeitos dos fármacos , Antinematódeos/farmacologia , Inseticidas/farmacologia , Fenalenos/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Sesquiterpenos/farmacologia , Tylenchoidea/efeitos dos fármacos , Aedes/crescimento & desenvolvimento , Aedes/efeitos da radiação , Animais , Antinematódeos/síntese química , Inseticidas/síntese química , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/efeitos da radiação , Luz , Estresse Oxidativo , Fenalenos/síntese química , Fármacos Fotossensibilizantes/síntese química , Sesquiterpenos/síntese química , Oxigênio Singlete/agonistas , Oxigênio Singlete/metabolismo , Relação Estrutura-Atividade , Tylenchoidea/crescimento & desenvolvimento , Tylenchoidea/efeitos da radiação
16.
J Vector Borne Dis ; 53(2): 144-8, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27353584

RESUMO

BACKGROUND & OBJECTIVES: Aedes aegypti, the primary vector of dengue generally breeds in intradomestic and peridomestic containers made up of different materials, i.e. plastic, iron, rubber, earthen material etc. The material of container is likely to affect the temperature of water in container with variation in environmental temperature. The present study was aimed to determine the effect of different container materials on larval development of Ae. aegypti at different temperatures. METHODS: Newly hatched I instar larvae (2-4 h old) were used in the study and experiments were conducted using three different containers made up of plastic, iron and earthen material. Three replicates for each type of container at 22, 26, 30, 34, 38, 40, and 42°C were placed in environmental chamber for the development of larvae. RESULTS: At temperatures >22°C, 50% pupation was completed in earthen pot within 4.3±0.6 to 6.3±0.6 days followed by plastic containers (5±0 to 8±0 days) and iron containers (6±0 to 9±0 days). Developmental time for 50% pupation in the three containers differed significantly (p < 0.05) at all the experimental temperature ranges. A significant variation was found in the temperature of environmental chamber and the temperature of water in three types of containers (p < 0.05). The difference in the temperatures of water in different containers resulted in significant variations in the developmental period of larvae. More than 35°C temperature of water was found inimical for pupal development. INTERPRETATION & CONCLUSION: The results revealed the variation in temperature of water in different types of containers depending on the material of container, affecting duration of larval development. As the larval development was faster in earthen pot as compared to plastic and iron containers, community should be discouraged for storing the water in earthen pots. However, in view of containers of different materials used by the community in different temperature zones in the country, further studies are required for devising area-specific preventive measures for Aedes breeding.


Assuntos
Aedes/crescimento & desenvolvimento , Aedes/efeitos da radiação , Mosquitos Vetores , Animais , Ecossistema , Larva/crescimento & desenvolvimento , Larva/efeitos da radiação , Temperatura , Água
17.
Med Vet Entomol ; 30(3): 278-85, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27091384

RESUMO

Hulecoeteomyia japonica japonica (= Aedes japonicus japonicus) (Diptera: Culicidae) (Theobald 1901), a container-breeding invasive species in North America and Europe, is attracting particular attention for its high local abundances and possible roles in the transmission of human and animal pathogens. The preferential habitats of this species are forested and bushy areas, which renders control measures extremely inefficient. Use of the sterile insect technique (SIT) may contribute to the implementation of area-wide integrated pest management strategies, as has been successfully proven with other aedine mosquito species. The present study investigates the effects of irradiation at a dose of 40 Gy on fitness parameters in H. j. japonica. Irradiation was performed on 16-24-h-old pupae from a colonized strain (PA) using a TrueBeam linear accelerator. Males from the PA strain were crossed with females of the same colony or with field-collected females. Irradiation induced a slight increase in mortality in male pupae, but did not alter the survival and mating abilities of emerging adult males. Rates of blood feeding and fertility were lower when PA strain males were kept with field-collected females rather than PA females. Irradiated males induced reductions in fertility (residual fertility: 2.6%) and fecundity in mated females. The data indicate that the SIT is a suitable technique to enhance the control of this species.


Assuntos
Aedes/efeitos da radiação , Controle Biológico de Vetores , Fótons , Pupa/efeitos da radiação , Animais , Feminino , Fertilidade/efeitos da radiação , Masculino , Reprodução/efeitos da radiação
18.
PLoS One ; 11(3): e0151864, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26990981

RESUMO

Combination of the sterile insect technique with the incompatible insect technique is considered to be a safe approach to control Aedes albopictus populations in the absence of an accurate and scalable sex separation system or genetic sexing strain. Our previous study has shown that the triple Wolbachia-infected Ae. albopictus strain (wAlbA, wAlbB and wPip) was suitable for mass rearing and females could be completely sterilized as pupae with a radiation dose of at least 28 Gy. However, whether this radiation dose can influence the mating competitiveness of the triple infected males was still unknown. In this study we aimed to evaluate the effects of irradiation on the male mating competitiveness of the triple infected strain under laboratory and semi-field conditions. The results herein indicate that irradiation with a lower, female-sterilizing dose has no negative impact on the longevity of triple infected males while a reduced lifespan was observed in the wild type males (wAlbA and wAlbB) irradiated with a higher male-sterilizing dose, in small cages. At different sterile: fertile release ratios in small cages, triple-infected males induced 39.8, 81.6 and 87.8% sterility in a wild type female population at 1:1, 5:1 and 10:1 release ratios, respectively, relative to a fertile control population. Similarly, irradiated triple infected males induced 31.3, 70.5 and 89.3% sterility at 1:1, 5:1 and 10:1 release ratios, respectively, again relative to the fertile control. Under semi-field conditions at a 5:1 release ratio, relative to wild type males, the mean male mating competitiveness index of 28 Gy irradiated triple-infected males was significantly higher than 35 Gy irradiated wild type males, while triple infected males showed no difference in mean mating competitiveness to either irradiated triple-infected or irradiated wild type males. An unexpected difference was also observed in the relative male mating competitiveness of the triple infected strain after irradiation at 28 Gy dose in small vs large cages, with a higher male mating competitiveness index calculated from results of experiments in the large cages. Based on these results, we consider that the male mating performance of the triple infected strain after irradiation at 28 Gy, a dose required for complete female sterility and the avoidance of population replacement, is approximately equal to that of the wild type males under semi-field conditions. Though field evaluation is required, this suggests that the triple infected strain is suitable for irradiation and release as part of a combined SIT-IIT approach to Ae. albopictus control.


Assuntos
Aedes/fisiologia , Controle de Mosquitos/métodos , Infecções por Rickettsiaceae/transmissão , Comportamento Sexual Animal , Wolbachia , Aedes/microbiologia , Aedes/efeitos da radiação , Animais , Feminino , Masculino , Infecções por Rickettsiaceae/prevenção & controle , Esterilização Reprodutiva
19.
PLoS One ; 11(1): e0146834, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26765951

RESUMO

The global expansion of Aedes albopictus together with the absence of vaccines for most of the arboviruses transmitted by this mosquito has stimulated the development of sterile-male strategies aiming at controlling disease transmission through the suppression of natural vector populations. In this context, two environmentally friendly control strategies, namely the Sterile Insect Technique (SIT) and the Wolbachia-based Incompatible Insect Technique (IIT) are currently being developed in several laboratories worldwide. So far however, there is a lack of comparative assessment of these strategies under the same controlled conditions. Here, we compared the mating capacities, i.e. insemination capacity, sterilization capacity and mating competitiveness of irradiated (35 Gy) and incompatible Ae. albopictus males at different ages and ratios under laboratory controlled conditions. Our data show that there was no significant difference in insemination capacity of irradiated and incompatible males, both male types showing lower capacities than untreated males at 1 day but recovering full capacity within 5 days following emergence. Regarding mating competitiveness trials, a global observed trend is that incompatible males tend to induce a lower hatching rate than irradiated males in cage controlled confrontations. More specifically, incompatible males were found more competitive than irradiated males in 5:1 ratio regardless of age, while irradiated males were only found more competitive than incompatible males in the 1:1 ratio at 10 days old. Overall, under the tested conditions, IIT seemed to be slightly more effective than SIT. However, considering that a single strategy will likely not be adapted to all environments, our data stimulates the need for comparative assessments of distinct strategies in up-scaled conditions in order to identify the most suitable and safe sterilizing technology to be implemented in a specific environmental setting and to identify the parameters requiring fine tuning in order to reach optimal release conditions.


Assuntos
Aedes/microbiologia , Aedes/efeitos da radiação , Controle de Mosquitos/métodos , Radiação Ionizante , Wolbachia , Animais , Feminino , Humanos , Masculino
20.
Recife; s.n; 2015. 85 p. ilus, graf.
Tese em Português | LILACS | ID: biblio-870275

RESUMO

Este estudo avaliou o desempenho biológico e reprodutivo de machos de Aedes aegypti esterilizados por radiação gama e seu potencial para uso no controle da espécie, através da técnica do inseto estéril (TIE). A eficácia de esterilização de diferentes doses de radiação gama, 30, 40 e 50 Gy, foi avaliada em machos irradiados (MI) na fase de pupa. O seu efeito sobre a longevidade e competitividade de acasalamento dos MI, sobre a fecundidade e fertilidade das fêmeas acasaladas com estes machos, bem como de fêmeas também irradiadas (FI), foram parâmetros analisados. Os testes de competitividade foram conduzidos em gaiolas teladas (2 X 2 m) em condições simuladas de campo, onde foram liberados machos irradiados e machos não irradiados (MNI), nas seguintes proporções: 5:1, 10:1 e 15:1. Os resultados revelaram que o fitness biológico e reprodutivo dos mosquitos são afetados pela radiação, de modo que os efeitos são diretamente proporcionais a dose de radiação utilizada. O parâmetro de longevidade apresentou diferenças significativas, tanto quando os MI foram analisados de forma individual quanto em grupo. Para a maior dose, MI e FI viveram em média 19,6 ± 2,2 dias e 25,8 ± 2,2 dias, respectivamente, enquanto que no grupo controle, estes valores foram de 24,9 ± 2,5 dias e 30,4 ± 2,5 dias...


This study evaluated the biological and reproductiv e performance of Aedes aegyptimales sterilized by gamma radiation and its potential for use in controlling the species through the Sterile Insect Technique (SIT). The sterilization efficacy of different doses of gamma radiation, 30, 40 and 50 Gy, was assessed in irradiated males (IM) in the pupal stage. The direct effects of gama radiation on the longevity and competitiveness of IM, as well as the effect on the fecundity and fertility of females mated with these males, and also irradiated females (IF), were analyzed. The competitiveness was examined by tests conducted in large cage (2 x 2 meters) in semi field conditions where irradiated males (IM) and non-irradiated males (NIM) were released in the following proportions: 5:1, 10:1 and 15:1. The results revealed that the biological and reproductive fitness of the mosquitoes are affected by radiation, so that the effects are directly proportional to the radiation dose. The longevity parameter showed significant differences...


Assuntos
Animais , Masculino , Feminino , Aedes/efeitos da radiação , Raios gama , Infertilidade , Controle de Insetos , Efeitos da Radiação , Aedes/crescimento & desenvolvimento , Brasil , Comportamento Competitivo/efeitos da radiação , Controle da População/métodos , Controle Biológico de Vetores , Área Urbana
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