Search

Desde que dio inicio el nuevo siglo, varios estudios sobre la culicidofauna de la Hispaniola han elevado el conocimiento de este grupo de artrópodos, muy relevantes desde el punto de vista médico y veterinario. En relación a la diversidad de la familia Culicidae, los hallazgos más recientes se han realizado en el municipio de Jarabacoa, República Dominicana. Con el objetivo de profundizar en la diversidad de los culícidos presentes en esta localidad montañosa de El Cibao, se procedió a la búsqueda de criaderos de mosquitos, sobre todo de origen natural, desde enero de 2018 hasta junio de 2019. La identificación de los especímenes se realizó mediante la utilización de lupa binocular y microscopio, con la ayuda de claves taxonómicas. Se reportan seis nuevas especies para Jarabacoa, sumando un total de 22 para el municipio, sobre las cuales se analizan cuestiones como su bioecología y su papel en la transmisión de agentes patógenos, entre otras. Destaca la presencia de Culex interrogator Dyar y Knab, 1906, especie que se reporta por primera vez en la Hispaniola, y por segunda en el Caribe insular. A pesar de que este culícido no está implicado hasta la fecha en la transmisión de patógenos al ser humano, otras especies encontradas en este estudio como Anopheles crucians Wiedemann, 1828, Aedes scapularis (Rondani, 1848) y Psorophora confinnis (Lynch Arribálzaga, 1891) deben ser tenidas en cuenta en los programas de vigilancia y control, a tenor de su relevancia médica.

The Psorophora confinnis complex is currently composed of three species--Psorophora confinnis sensu stricto (Lynch Arribalzaga) in South America, Psorophora columbiae (Dyar and Knab) in North America, and Psorophora jamaicensis (Theobald) in the Caribbean. Members of the complex are of considerable importance as vectors of arboviruses, for example, Venezuelan equine encephalitis virus, and are significant biting pests throughout their range. The biological and geographic boundaries of Ps. confinnis and Ps. columbiae are unclear. In fact, the name Ps. columbiae is presently designated as "provisional." In this article, we aim to clarify the taxonomy and geographic distributions of species within the Ps. confinnis complex. A population genetics approach was employed using gene and genotypic frequency data at 26 isozyme loci. The results suggest that the Ps. confinnis complex in North and South America is composed of four species. Ps. confinnis s.s. and Ps. columbiae are distinct species in South and North America, respectively. Populations in Colombia, South America, formally designated as Ps. funiculus (Dyar) and populations in the southwestern United States and western Mexico, formally designated Ps. toltecum (Dyar and Knab), are distinct species. Psorophora toltecum and Psorophora funiculus species names should be resurrected from synonymy. In addition we identified a Ps. columbiae and Ps. toltecum hybrid zone in central Texas in a region described as being one of 13 North American suture zones, being geographical areas in which closely related species occur in sympatry and frequently hybridize.

Introducción. En los últimos 18 años, no se han vuelto a registrar epizootias de encefalitis equina venezolana en áreas con antecedentes históricos de epidemia (1925-1995) en la península de La Guajira. Objetivo. Establecer si en la Alta Guajira colombiana se mantienen las condiciones que favorecen la reaparición de las cepas epizoóticas del virus de la encefalitis equina venezolana. Materiales y métodos. La investigación se realizó en las localidades afectadas por la epidemia de 1995, y se evaluaron los siguientes aspectos: 1) abundancia y variación estacional de las poblaciones de los mosquitos vectores; 2) disponibilidad de mamíferos sensibles amplificadores del virus, y 3) conocimiento de los habitantes sobre la enfermedad y sus vectores. Resultados. La mayoría de las especies de mosquitos, incluidas las de los vectores, se encontraron durante la estación lluviosa. Aedes taeniorhynchus y Psorophora confinnis presentaron relación con la precipitación y la temperatura. Deinocerites atlanticus estuvo siempre presente, independientemente de las condiciones climáticas. No se encontraron anticuerpos de tipo IgG en los sueros de humanos menores de 17 años, tampoco en los de los animales caprinos y bovinos analizados. En la encuesta sobre conocimientos, se detectó que la tercera parte de los encuestados recordaba la última epidemia y tenía conocimientos básicos sobre la enfermedad. Solamente 20 % de las familias poseía équidos y el 8 % estaba informado sobre la necesidad de vacunarlos. Conclusiones. Se mantienen algunas condiciones epidemiológicas que eventualmente podrían favorecer la reaparición del virus, pero el número de equinos en riesgo es escaso, lo cual constituye el cambio más notable y lo que, aparentemente, ha impedido la reaparición del virus.

A new cell line, PC-0199-BR, was established from embryonated eggs of the mosquito Psorophora confinnis. To date (September 2000) it has had 62 continuous passages. This is the first report of a cell line of mosquitoes belonging to the genus Psorophora. Cell growth initially was achieved in the MM/VP12 medium, supplemented with 20% fetal bovine serum; however, the subcultures were later adapted to Grace's medium with 10% fetal bovine serum. Cell morphology in the primary cultures was heterogeneous; but later in the established cell line, the predominant cell type was epithelioid. Cultured cells were predominantly diploid (2n=6); however, chromosome abnormalities were observed in a small proportion of the cells in later passages. C and G band patterns were also determined in the karyotype. The cell line isozyme profiles coincided with pupae and adult samples of the species taken from the same colony. A preliminary arbovirus susceptibility study for the cell line was undertaken. No evidence was observed of contamination of the cell line with bacteria, fungi or mycoplasma.

Con el propósito de comparar citogenéticamente dos cepas colombianas del mosquito Psorophora confinnis, procedentes de Lorica (Córdoba) y Granada (Meta), se efectuó un estudio de caracterización cariológica. A partir de tejidos cerebrales de lamas de IV estadio, se prepararon los cromosomas mitóticos mediante la técnica de aplastamiento (squash) del tejido. Se efectuaron las mediciones cromosómicas. atendiendo a los siguientes parámetros: brazo corto. brazo largo, relación de brazos. longitud total, longitud relativa, índice centromérico y longitud relativa de los cromosomas. Se compararon los cálculos morfométricos y se aplicaron patrones estandarizados para clasificar los cromosomas en los cariotipos analizados. Se registraron diferencias altamente significativas en la longitud total cromosómica y también en los valores de los brazos cortos y largos de los cromosomas, en las metafases obtenidas de las dos cepas. Teniendo en cuenta los patrones de bandas C y G, se estableció correctamente la ubicación del centrómero y las reqiones heterocromáticas asociadas a él e. iqualmente. el número de bandas en cada uno de los pares cromosómicos en el cariotipo de lascepas de Lorica y Granada. Los resultados de los datos morfométricos y de los fenotipos de bandas sugieren que Ps. confinnis existe en Colombia como un complejo de especies.

The developmental times, eclosion to emergence, of 18 broods of Psorophora confinnis Lynch Arribalzaga, observed in irrigated date groves in the Coachella Valley, Calif., ranged from 78 to 126 hours with a mean of 97 hours at average water temperatures of 77–88°F. In 38% of the broods, all pupae were stranded on mud by the disappearance of open water, but 50%–95% of these metamorphosed successfully although stranded for as much as 15 hours. Thus, at summer temperatures, irrigation water needs to persist only 3–3.5 days to permit emergence. At constant water temperatures of 65°–95°F, developmental time varied inversely with temperature, but the effect of a 5° increase was progressively less as temperature increased. Total development was fastest (86–89 hours) at 90°–95°F. Survival, from second-instar larva to adult, was maximum at 75°–85°F. For each immature stage there is agreement between the constant temperatures which allowed good survival in the laboratory and the range of water temperatures encountered in nature. The first- and second-instar larvae were most susceptible to temperature extremes; later stages were progressively more resistant. Pupae appeared normal at 115°F and metamorphosed after such exposure. The rapid development from eclosion to emergence and the high tolerance of the pupae, together with their ability to metamorphose on mud, are significant adaptations of the Coachella Valley populations of P. confinnis .

Nerves connecting larval and pupal setae of prepupal mosquitoes were used to establish the homologies of the abdominal setae. Both larval and pupal setal patterns were then utilized to deduce serial (segment to segment) homologies. The chaetotactic system proposed is based on previous ones but contains several modifications suggested by the present work. The studies described were clone with prepupae of Culiseta inornata (Williston), Culex pipiens quinquefasciatus Say and Psorophora confinnis (Lynch Arribalzaga).

The seasonal hatching of the eggs is controlled by the annual cycle of temperature. Preflooding temperatures control the hatchability of the eggs by exerting a conditioning or deconditioning effect. The eggs are conditioned by an increase in temperature and deconditioned by a decrease. All eggs are conditioned when held at 90°F for 1–2 weeks and deconditioned after 4 weeks at 60°. Intermediate temperatures may either condition or decondition the eggs, depending upon the previous temperature of exposure, since conditioning occurs only at temperatures higher than the prior deconditioning temperature. Thus, temperatures of 70° and 80° condition eggs in late spring and early summer, and decondition eggs in late summer and early autumn. The percentage of conditioned eggs that hatch when flooded varies directly with the temperature of the medium. The combined effects of preflooding and flooding temperatures upon the hatching of the eggs control the seasonal occurrence of adults. Deconditioned eggs do not hatch during the winter, although repeatedly flooded by irrigation water.

During a 2-year study (1969-70), Psorophora confinnis (Lynch-Arribalzaga), Anopheles quadrimaculatus Say, and A. crucians Wiedemann populations caused statistically significant and economically damaging reductions in the average daily gain of feedlot steers. Steers on a high-energy-level ration (20% roughage) and steers on a low-energy-level ration (60% roughage) that were protected from mosquito attack gained significantly more ( P ‘0.01) during certain periods than steers on the same rations exposed to mosquito attack in 1969 and 1970. During these periods of loss in weight-gain efficiency, 6.8-114.7 blood-fed mosquitoes/ft2 wall were observed in the unscreened barn from 30 to 120 min after official sunset. Steers on the low-energy-level ration which were protected from mosquito attack gained in 1969 18.2 lb/head and sold for $5.78/head and in 1970 gained 45.5 lb/head and sold for $13.12/head more than unprotected steers on the same ration. Mosquito attack did not reduce the economic value of the steers on the high-energy level ration in 1969 and reduced their value only by $0.35/head in 1970 No overall significant difference was found between the average daily feed intake of the steers which were exposed to mosquito attack and those protected by screen wire. Larger numbers of blood-fed mosquitoes were observed in the barn 60, 90, and 120 min after official sunset than at 30 minutes after sunset ( P ‘0.01). However, the rate of increase from 90 to 120 minutes after official sunset was much less than that observed during the 1st 90 minutes.

Parasites of the genus Thelohania were studied in 13 species of mosquitoes collected from two parishes in southwestern Louisiana. New host records were established for Aedes grossbecki, A. sollicitans, A. sticticus, A. taeniorhynchus, Culex salinarius, Psorophora confinnis , and Anopheles bradleyi . The host-parasite relationships of the mosquitoes and associated Thelohania were classified into four types.

Small-plot and outfield tests were conducted to determine the amount required and best method of FLIT® MLO application to control Psorophora confinnis (Lynch-Arribalzaga) in Louisiana. Larval mortality was determined 24 hours following application. At the 0.5 gal/acre rate, the spray and pour-on applications of the material caused 97% mortality to first-stage larvae, while the drip-bucket and capsule applications effected 94 and 90% mortality, respectively. In small-plot tests, the film caused 96% or greater larval mortality at the 2.0 gal/acre rate regardless of the method of application. Spray and capsule application of the material at 0.5 gal/acre resulted in 99% larval mortality in the outfield tests, while 1.0 gal/acre rates were necessary to achieve the same degree of control with the drip-bucket and pour-on methods. The yields of rice in 1968 and 1969 for each method and rate of application indicated that no reduction occurred through use of the surface film. FLIT MLO was not detected in rice grain or straw from plots which had been sprayed with 2.0 gal/acre. An LC50 of 0.34 gal/acre equivalent and an LC90 of 0.53 gal/acre equivalent were determined for P. confinnis pupae.

Newly emerged females of 11 species of Florida mosquitoes were flown in sound-recording boxes at 27°C under LD 12:12 to investigate the effects of temporary crowding during larval stages on the spontaneous flight activity patterns. None of the species investigated exhibited the migratory type flight activity pattern which could be attributable to temporary crowding rearing conditions. Only 4 species, Psorophora confinnis, Culex nigripalpus, Culex Pipiens quinquifasciatus, and Anopheles quadrimaculatus distinctly showed increased flight activity during the first 3 days after emergence when reared under temporary crowding rearing conditions. Seven other species showed at most a very slight increase in flight activity which could be attributed to temporary crowding rearing conditions. The duration of teneral period appears to be species specific and affected by the larval rearing conditions. Most of the species investigated did not show entrainment to light and dark cycles before 48 hr after emergence.

Summary The present paper reports a series of observations on the habits of the adult mosquitoes dwelling in the llanos, the grass land of Eastern Colombia. The observations summarized here were made during the rainy season, in the months of June, July and November, 1948 and June, 1949. Captures of adult mosquitoes were made by means of stable traps and with muslin tents covering an area of 4 sq. m. of ground. Catches of flying mosquitoes were also made using nets of strong muslin, fixed to a moving vehicle. The tent captures were made in series along a straight line stretching from a breeding place to the middle of an expanse of savanna. They were all made during daytime, between 7 A.M. and 5 P.M. The grass under the tent was sprayed with citronella in order to disturb the resting mosquitoes, which were then easily caught on the sides and cover of the tent. Each trial took between 15 and 20 minutes time. In a total of 104 captures, an average mosquito density of 11.9 mosquitoes per trial was obtained. Culicines formed the bulk of these captures. The average anopheline density was 1.2 mosquitoes per trial. As the type of tent used covers 4 sq. m. of ground, this means a density of roughly 3 million mosquitoes per sq. km. and 300,000 anophelines per sq. km. Males and females of A. peryassui, A. pessoai and A. parvus were found resting in the grass. A male of A. punctimacula was also found in these captures. The commonest culicine species were Culex chrysonotum, Culex (Melanoconion) sp. and Psorophora confinnis. Direct observation showed that usually the mosquitoes were resting in the grass at no more than 10 cm. above the ground. A total of 570 male culicines and 536 females were caught in the 104 trials, which may be taken as an indication of a similar span of life among both sexes. Total number of anophelines was 30 males and 98 females, perhaps too small a sample to draw any definite conclusions as regards survival. The average fertilization rate among both groups was 81 per cent, which indicates that mating occurs in all probability shortly after the emergence of the adults. In the course of these studies it was noticed that usually a mosquito breeding place can be found anywhere in the llanos at no more that 1,000 to 1,500 m. distance. The maximum distance recorded from a breeding place was 1,800 m. Female mosquito density proved to be nearly uniform across the savannas, but male mosquito density was found to be higher near the breeding places than far away from them. Such findings demonstrate that, at least during the rainy season, any part of the savannas of the llanos is within the effective flight range of the species living there. A series of parallel stable trap captures made in the vicinity of a breeding area and at a distance of 1 km. gave a mosquito density approximately the same for both locations. Stable trap captures yielded a good number of anophelines but they gave inadequate information as regards the culicines. Tent captures and captures from a moving vehicle, are considered superior to the ordinary way of trapping to obtain direct information on the real mosquito density and on the composition of the mosquito fauna in a savanna country. Biting activity of mosquitoes was measured over a 24 hour cycle by periodical removal of the mosquitoes entering a baited stable trap. Maximum activity took place shortly after sunset, continued during the night and had a slight increase before sunrise. Mosquito activity during the day was practically nil. Direct observations were made of sexual activities. Swarms of culicines were seen over the savannas as early as 5 P.M., but mating of anophelines was only observed on two occasions at 7 P.M.; swarming males captured then proved to be A. peryassui.

Massive populations of the dark rice field mosquito, Psorophora confinnis (Lynch-Arribalzaga), are produced in southwestern Louisiana by the water management methods used in the cultivation of rice.