Metodologias alternativas no controlo integrado de larvas de mosquitos nas áreas urbanas: técnicas de obliteração da superfície da água

The public health risk associated to mosquitoes has increased in Spain by the introduction of the Asian Tiger Mosquito (Aedes albopictus) which is a well-known disease vector. Integrated control methodologies basically rely on larviciding by weekly applications of microbial biocides that have no residual effect. In some special cases, such as swimming pools in abandoned estates, this weekly schedule cannot be achieved due to difficulties of access and operational reasons. In these circumstances, there are no appropriate biocidal options except for Insect Growth Regulators (IGR), which do not provide more than a few weeks of residual efficiency. We present here the practical application of a well-known technique for controlling mosquito larvae in urban environments by altering the water/air interface. The adding to the water surface of a thick layer of beads made from inert, floating materials is described. The layer of beads impedes oviposition and adversely affects the breathing of the larvae. This technique avoids the regular application of chemical pesticides, as well as providing improved sustainability and higher efficiency times. Caution notes and side effects are also discussed.Los mosquitos son un riesgo relevante para la salud pública que se ha visto incrementado con la llegada de Aedes albopictus, el mosquito tigre, potencial transmisor de varias enfermedades. El método de elección para su control es la eliminación de las larvas acuáticas mediante biocidas de origen biológico, que se realiza semanalmente debido a su nula persistencia. En determinados puntos donde esta periodicidad no puede mantenerse, como piscinas en fincas abandonadas, no existen opciones biocidas adecuadas más residuales exceptuando los inhibidores del crecimiento, que sin embargo no suelen proporcionar una residualidad superior a unas pocas semanas (de dos a cuatro). Se presenta la aplicación práctica de una técnica de control de larvas de mosquito en medios urbanos consistente en alterar la interfase agua/aire. Se describe la aplicación de materiales granulados inertes flotantes sobre las superficies para impedir la puesta de huevos y la respiración de las larvas, con el consiguiente beneficio de evitar la aplicación periódica de plaguicidas químicos, así como una sostenibilidad y perduración muy superiores. Se discuten asimismo los riesgos propios de estas estrategias.Os mosquitos são um risco significativo para a saúde pública, que aumentou com a chegada do Aedes albopictus, mosquito tigre, potencial transmissor de várias doenças. O método de escolha para o seu controle é a eliminação das larvas aquáticas com produtos biocidas de origem biológica, realizada semanalmente devido a sua persistência nula. Em determinados pontos onde essa recorrência não pode ser mantida, como piscinas em fazendas abandonadas, não há suficientes opções residuais biocidas com excepção dos inibidores de crescimento, mas não costumam fornecer um residual maior do que duas a quatro semanas. Apresenta-se a aplicação prática de uma técnica de controle de larvas do mosquito em ambientes urbanos consistendo em alterar a interface água/ar. Descreve-se a aplicação de materiais granulados inertes flutuando na superfície para evitar a postura de ovos e respiração das larvas, com o consequente benefício de evitar a aplicação periódica de pesticidas químicos, com uma melhor sustentabilidade e duração. Discutimos também os riscos inerentes a estas estratégias

Anàlisi sobre dos ecotipus de Culex (Culex) pipiens Linnaeus, 1758 (Diptera: Culicidae) al Baix Llobregat

Hom ha abordat l'estudi del complex del mosquit Culex pipiens Linnaeus, 1758. La hipòtesi de treball fou que poblacions d'aquest mosquit, que poden pondre ous sense ingesta prèvia de sang (poblacions autògenes), podrien constituir per alguns autors una entitat taxonòmica diferent, Culex molestus Forskal, 1775, aïllada genèticament en biòtops subterranis tancats, i amb caràcters morfològics diferencials respecte de Culex pipiens s.s. Per provar aquesta hipòtesi, un total de 74 poblacions larvàries foren mostrejades en els anys 1993 i 1994 en diferents biòtops del Baix Llobregat (Barcelona, Espanya) per ser analitzades simultàniament des del punt de vista de l'autogènia, la morfologia, la dinàmica de poblacions i els fluxos gènics entre diferents hàbitats. Les poblacions larvàries d'hàbitats subterranis tancats presentaven un percentatge més elevat de femelles autògenes, i l'autogènia era significativament associada a certs caràcters morfològics, tot i que no posseïen valor diagnòstic. Com que els intercanvis genètics eren amplis entre hàbitats, no es recolzà la validesa taxonòmica de Culex molestus, donant a l'autogènia només un valor d'adaptació fisiològica. L'anàlisi dels al?lels de resistència a insecticides organofosforats va trobar-los en altes freqüències, tot i que els mosquits deixaren de controlar-se amb aquests productes des del 1992. El manteniment de la resistència podria ser afavorit per residus de plaguicides agrícoles en l'aigua. Es proposà un model dinàmic sobre aquesta informació, incloent també la influència de les activitats humanes de control de mosquits com a factor d'increment de la deriva genètica.Taxonomic differentation was assessed in the mosquito species-complex Culex pipiens Linnaeus, 1758. The working hypothesis was that autogenous populations (i.e. those containing females that can lay their first egg batch without a blood meal) could represent a separate species, Culex molestus, morphological differentiated and ecologically isolated in closed underground habitats. A total of 74 populations were sampled from different habitats in the Baix Llobregat area, near Barcelona in Spain, during 1993 and 1994 in order to assess autogeny, morphology, population dynamics and gene flow between habitats. Larval populations from closed underground habitats showes a higher percentage of auto- genous females. The autogeny was related to certain morphological characters, although these lacked diagnostic value. Since the gene flow between habitats was estimated to be high, the taxonomic validity of Culex molestus is not supported, and the autogeny is considered to be only a physiological adaptation. In addition, analysis of organophosphate pesticide resistance revealed high frequencies of resistance alleles up to two years after the withdrawal of these products. Maintenance of the resistance could be favoured by agricultural pesticide residues in the water. A dynamic model is proposed that incorporates this data and also includes the influence of human mosquito-control activities as a factor increasing genetic drift.Se abordó la diferenciación en el complejo del mosquito Culex pipiens Linnaeus. La hipótesis de partida fue que poblaciones autógenas de esta especie (es decir, que pueden poner sus huevos sin ingerir sangre previamente) podrían constituir según algunos autores la entidad taxonómica diferenciada Culex molestus Forskal, 1775, aislada genéticamente en biotopos subterráneos cerrados, y con caracteres morfológicos diferenciales. Un total de 74 poblaciones larvarias fueron muestreadas en los años 1993 y 1994 en diferentes biotopos del Baix Llobregat (Barcelona, España) para ser analizadas simultáneamente desde los puntos de vista de la autogenia, la morfología, la dinámica de poblaciones y flujos génicos entre diferentes biotopos. Las poblaciones larvarias de biotopos subterráneos cerrados presentaban un porcentaje mayor de hembras autógenas. La autogenia estuvo significativamente asociada con ciertos caracteres morfológicos, los cuales no poseyeron sin embargo valor diagnóstico. Puesto que además los intercambios genéticos entre hábitats eran importantes, no se confirmó la validez taxonómica de Culex molestus, valorándose la autogenia únicamente como una adaptación fisiológica. Los alelos de resistencia a insecticidas organofosforados se hallaron en altas frecuencias a pesar de haberse abandonado estos productos para el control de mosquitos en 1992. El mantenimiento de estos alelos podría ser consecuencia de la presencia de residuos de plaguicidas agrícolas en el agua. Se propuso un modelo dinámico sobre el conjunto de los datos, que incluye también la influencia de las actividades humanas de control de mosquitos como un factor importante de incremento de la deriva genética

Mosquits de la comarca del Baix Llobregat (Diptera, Culicidae)

Des de l'octubre de 1991 fins al març de 1993 es van estudiar les poblacions de Culicidae (Diptera) de la comarca del Baix Llobregat, i es van completar les dades que d'aquest grup es tenien al Servei de Control de Mosquits del Baix Llobregat. S'han examinat 169 mostres amb un total de 4.324 individus en estat larvari, obtingudes de la prospecció directa de 107 focus, i 3.863 individus adults obtinguts de la col·locació de 470 trampes de CO2, en 91 punts diferents. Les trampes tenien una freqüència setmanal i es col·locaven al llarg d'una nit. Això ha permès citar 17 espècies agrupades en 6 gèneres i obtenir dades de la seva fenologia. D'altra banda s'han pogut caracteritzar els diferents biótops larvaris agrupant-los en nou categories diferents i descriure la culícidofauna associada a cadascun d'ells. En estudiar les associacions larvàries d'espècies s'ha observat que la presència o absència d'associació ve determinada pel tipus de focus i no per la presència o absència d'altres espècies.Mosquitoes (Diptera, Culicidae) of the Baix Llobregat Area (Barcelona, Spain). Culicidae (Diptera) from the Baix Llobregat area were studied from October 1991 until March 1993. This work is a completion of data already gathered by the Baix Llobregat Mosquito Control Service. 4.324 larvae of 169 samples, taken from 107 larval focuses, were studied, as well as 3.863 adults collected by 470 CO2 traps, placed in 91 different localities. Traps were installed weekly all through the night. The study results in 17 species grouped in 6 genera, and allows to obtain phenological data. On the other hand, larval biotopes could be classified in 9 different categories, and their mosquito fauna is described. When biocenoses are considered, it comes out that they are determined by the biotope characteristics, and not by reciprocal incompatibilities between species

Phenotypic insecticide resistance in arbovirus mosquito vectors in Catalonia and its capital Barcelona (Spain)

A range of mosquito species that belong to the Culicidae family are responsible for the worldwide transmission of infectious arboviral diseases such as dengue fever, Zika, West Nile fever and Chikungunya fever. Spain is at risk of arbovirus outbreaks, as various arboviral diseases are frequently introduced and it has established competent vector populations. Autochthonous human cases of West Nile virus have been reported infrequently since 2004, and since October 2018 three autochthonous human case of dengue fever have been confirmed. In response to an outbreak of any arboviral disease, space spraying or fogging will be implemented to control adult mosquito populations. To ensure adulticiding is costeffective, the insecticide susceptibility status of vectors throughout Catalonia, an autonomous region in north-eastern Spain, was assessed through standardized WHO tube and CDC bottle bioassays. All Culex pipiens populations tested were resistant to at least one of the pyrethroids tested, whereas Aedes albopictus populations were susceptible to all pyrethroids tested. More detailed studies on the Cx. pipiens populations from the Barcelona area (the capital and largest city of Catalonia) revealed resistance to all four classes of public health insecticides available (pyrethroids, carbamates, organophosphates and organochlorides). All Ae. albopictus populations were susceptible to those classes, except for one of the tests performed with pirimiphos-methyl (an organophosphate). Pyrethroids are currently the first line chemical class to be used in space spray operations in response to an outbreak of an arboviral disease. While pyrethroids can be effective in reducing Ae. albopictus populations, this class may not be effective to control Cx. pipiens populations.info:eu-repo/semantics/publishedVersio

Aplicación de adulticidas para el control de Aedes albopictus

Debido a la importancia sanitaria y a las molestias causadas por el mosquito invasor Aedes albopictus, se ha de promover su control, siendo el Control Integrado de Vectores (CIV) el enfoque más racional para conseguirlo. Los tratamientos adulticidas, como solución última del CIV, han sido pobremente estudiados en Europa, probablemente por los escasos brotes autóctonos de arbovirosis donde Ae. albopictus ha ejercido como vector. En esta memoria de tesis se han estudiado los dos principales métodos de aplicación de adulticidas: tratamientos volumétricos y de impregnación (sobre vegetación), evaluando diferentes aspectos de su eficacia frente a Ae. albopictus. Los tratamientos en ultra bajo volumen (ULV) con Deltametrina, aunque pueden alcanzar eficacias del 100% a los 25 metros en campo abierto y con condiciones meteorológicas favorables, tienen una persistencia reducida, pueden entrañar riesgos a causa de la deriva del producto y se adaptan mal a la biología de Ae. albopictus. Por otro lado, los tratamientos de impregnación de la vegetación alcanzan mejor las zonas de descanso de Ae. albopictus y confieren además una mayor persistencia, causando una mortalidad del 70% a los 19 días con Deltametrina, aunque este efecto residual puede favorecer la selección de poblaciones resistentes. El estado de susceptibilidad de 4 poblaciones españolas de Ae. albopictus también fue evaluado, comparándolo con las concentraciones discriminantes (Deltametrina 0.05%, Permetrina 1% y Cipermetrina 0.1%) obtenidas con una cepa susceptible de laboratorio. Se detectó por primera vez en Europa una población de Ae albopictus resistente a un piretroide (Cipermetrina), lo que sugiere que el uso de adulticidas debería de estar mejor regulado, para que Ae. albopictus no llegue a desarrollar las resistencias que ya presenta Ae. aegypti en otras partes del mundo. <br /

Modelling the Dynamics of an Aedes albopictus Population

We present a methodology for modelling population dynamics with formal means of computer science. This allows unambiguous description of systems and application of analysis tools such as simulators and model checkers. In particular, the dynamics of a population of Aedes albopictus (a species of mosquito) and its modelling with the Stochastic Calculus of Looping Sequences (Stochastic CLS) are considered. The use of Stochastic CLS to model population dynamics requires an extension which allows environmental events (such as changes in the temperature and rainfalls) to be taken into account. A simulator for the constructed model is developed via translation into the specification language Maude, and used to compare the dynamics obtained from the model with real data.Comment: In Proceedings AMCA-POP 2010, arXiv:1008.314

Mosquito alert: leveraging citizen science to create a GBIF mosquito occurrence dataset

The Mosquito Alert dataset includes occurrence records of adult mosquitoes collected worldwide in 2014-2020 through Mosquito Alert, a citizen science system for investigating and managing disease-carrying mosquitoes. Records are linked to citizen science-submitted photographs and validated by entomologists to determine the presence of five targeted European mosquito vectors: Aedes albopictus, Ae. aegypti, Ae. japonicus, Ae. koreicus, and Culex pipiens. Most records are from Spain, reflecting Spanish national and regional funding, but since autumn 2020 substantial records from other European countries are included, thanks to volunteer entomologists coordinated by the AIM-COST Action, and to technological developments to increase scalability. Among other applications, the Mosquito Alert dataset will help develop citizen science-based early warning systems for mosquito-borne disease risk. It can also be reused for modelling vector exposure risk, or to train machine-learning detection and classification routines on the linked images, to assist with data validation and establishing automated alert systems

Arbovirus surveillance: first dengue virus detection in local Aedes albopictus mosquitoes in Europe, Catalonia, Spain, 2015

Dengue has emerged as the most important viral mosquito-borne disease globally. The current risk of dengue outbreaks in Europe appeared with the introduction of the vector Aedes albopictus mosquito in Mediterranean countries. Considering the increasing frequency of dengue epidemics worldwide and the movement of viraemic hosts, it is expected that new autochthonous cases will occur in the future in Europe. Arbovirus surveillance started in Catalonia in 2015 to monitor imported cases and detect possible local arboviral transmission. During 2015, 131 patients with a recent travel history to endemic countries were tested for dengue virus (DENV) and 65 dengue cases were detected. Twenty-eight patients with a febrile illness were viraemic, as demonstrated by a positive real-time RT-PCR test for DENV in serum samples. Entomological investigations around the viraemic cases led to the detection of DENV in a pool of local Ae. albopictus captured in the residency of one case. The sequence of the DENV envelope gene detected in the mosquito pool was identical to that detected in the patient. Our results show how entomological surveillance conducted around viraemic travellers can be effective for early detection of DENV in mosquitoes and thus might help to prevent possible autochthonous transmission