A key, based on wing patterns of biting midges (genus <i>Culicoides</i> Latreille - Diptera: Ceratopogonidae) in the Iberian Peninsula, for use in epidemiological studies

Abstract

The identity of vectors of disease are often required speedily in epidemiological studies but with a precision which excludes as many other species as possible. Identification keys usually require the examination of many different parts of the suspected vector to pinpoint the species. This consumes considerable time and resources, so epidemiologists tend to ignore them. A simplified approach to identification is proposed, using the characteristics of a single part of the body (the wings) of biting midges of the genus Culicoides. The level of differentiation was epidemiologically valuable. The monoclave could not differentiate all the species from each other but more than one third (20/58) of identifications were for single species, and a further 12/58 identifications gave only two possibilities, making 55.2% of identifications to an accuracy of at most one of two species. The diagnosis of vector species was reached in a maximum of six decision points. The only notable exception to valuable differentiation was the four species in the Culicoides obsoletus group which had almost identical female wing patterns. The ready availability of simple keys, which can be used by anyone without formal training in taxonomy, for all the species of a group in a region should encourage greater standardisation of identifications in all studies, including those not primarily aimed at systematics. These monoclaves can also serve as the primary tools to build computerised image-recognition systems for genera, families and orders of insects. Keywords: Culicoides, biting midges, vectors, epidemiology, identification, wing patterns, Iberian peninsula, monoclave. RESUMENClave de patrones alares de ceratopogónidos del género Culicoides Latreille (Diptera: Ceratopogonidae) en la Península Ibérica, para estudios epidemiológicos Con frequencia en los estudios epidemiológicos hace falta conocer con rapidez, pero también con precisión, la identidad de los vectores. Por lo general los procedimientos de identificación y las claves exigen el examen de un elevado número de partes diferentes del vector sospechoso. Este enfoque consume mucho tiempo y recursos por lo que tiende a ser evitado por los epidemiólogos. Se propone un sistema simplificado para la identificación, el cual utiliza las caracteristicas de sólo una parte del cuerpo (las alas) de los ceratopogónidos del género Culicoides. El nivel de diferenciación es bueno (55.2 % de las 58 especies presentes) y abarca casi todas las especies implicadas en la transmisión de virus y otros agentes patógenos de animales en la Península Ibérica. El diagnóstico de una especie precisa un máximo de seis criterios. La única excepción importante la constituyen las cuatro especies del grupo Culicoides obsoletus, las hembras de las cuales muestran un diseño alar casi idén-tico. La utilización de claves sencillas debería proporcionar una mejor estandarización de la identificación en todos los estudios, incluso los realizados por no sistemáticos. Estas claves pueden servir como el instrumento más impo...

Molecular detection of bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) in captured Culicoides spp. in the northeastern regions of Mexico

“…So biting midges trapped were identified only at basic phenotypic level to determine if they belong to the genus Culicoides. In addition, the basic phenotypic identification of all midges captured showed that all specimens corresponded to the Culicoides variipennis complex (Coquillett) (Wirth, 1957;Borror et al, 1989;Rawlings, 1996). Midges of C. variipennis complex comprise the species C. variipennis, C. sonorensis and C. occidentalis (Schmidtmann et al, 2011;Tabachnick, 1996).…”

“…Previous separation of other captured insects, Culicoides (Culicoides, Diptera: Ceratopogonidae) were identified with the aid of a binocular stereoscopic microscope (Carl Zeiss) according to the characteristics observed in the wings as reported by Rawlings (1996) and Borror et al (1989). The identification is based on the characteristic pattern of dark and light areas of the wings, the dorsal side of the thorax, size and shape of the segment of the antennas, the relative position of the eyes, the shape of the spermathecal in females and the shape of the genitals in males (Meiswinkel et al, 2004;Werner and Kampen, 2007).…”

New insights on diversity, morphology and distribution of Culicoides Latreille 1809 (Diptera: Ceratopogonidae) from Northeast Spain

“…One female had sensillae coeloconica in antennal segment 4, and was lacking in the 12 th , whereas another female had sensillae coeloconica in the 6 th segment. (Khalaf 1961) and C. odiatus female (Austen 1921) and male (Edwards 1939) has been widely accepted (Boorman 1989;Glukhova 1989;Rawlings 1996). However diff erences in thoracic pattern and male genitalia can be detected when comparing original descriptions of both species.…”

Field sampling methods for mosquitoes, sandflies, biting midges and ticks

“…Culicoides are initially identified under a stereomicroscope at species-group level according to wing pattern morphology, using main taxonomic keys for palaearctic Culicoides [56][57][58][59][60]. Specimens will then be identified down to species level.…”