Assessment of Culex pipiens bioforms in the world's southernmost distribution limit

The mosquito Culex pipiens s.s. L. occurs as two bioforms that differ in physiology and behaviour affecting virus transmission cycles. To assess the occurrence of Cx. pipiens bioforms in the southernmost limit of its distribution, specimens were collected aboveground in southern Buenos Aires Province and east Patagonia, Argentina. Ten larvae and 25 adults were individually processed and identified by polymerase chain reaction (PCR) amplification of Ace-2 and CQ11 loci. Culex quinquefasciatus Say (one larva, two adults), Cx. pipiens f. molestus (one larva, one adult) and one adult of hybrid origin were identified in Buenos Aires Province; only Cx. pipiens f. molestus was recorded in Patagonia (eight larvae, 21 adults). The potential absence of bioform pipiens and its implications in arbovirus enzootic cycles is discussed.

Detección molecular de virus de encefalitis de Saint Louis en mosquitos de Buenos Aires, Argentina

Durante el mes de marzo de 2013 una población de palomas torcazas (Zenaida auriculata) se instaló en una zona céntrica de la ciudad de Buenos Aires. Conociendo el rol que poseen estas aves como hospedadores competentes del virus de la encefalitis de Saint Louis (SLEV), fue colocada en el lugar una trampa de luz tipo CDC, a fin de realizar una vigilancia entomológica. Durante ese mes,fueron capturados 5 grupos de mosquitos (n = 48), 3 correspondieron a la especie Culex pipiens (n = 10) y 2 a Culex spp.(n = 38), no pudiéndose determinar en estos últimos con precisión la especie por encontrarse dañados. En un grupo de mosquitos Culex spp. se detectó el SLEV por técnicas moleculares. Posteriormente fue secuenciado y clasificado como perteneciente al genotipo III.

During March 2013 a population of eared doves (Zenaida auriculata) was established in the center of City of Buenos Aires. Considering the role of these birds as host competent for Saint Louis encephalitis virus (SLEV), a CDC light trap was put in place to perform entomologic surveillance. During this month 5 pools of mosquitoes (n = 48) were collected and taxonomically determined. Three of them were classified as Culex pipiens (n = 10) and the other two were Culex spp. (n = 38). In this case, the mosquitoes species could not be determined due to that individuals were damaged. One of the Culex spp. pool was found to be positive for Saint Louis encephalitis virus by molecular techniques. This was then sequenced and classified as genotype III.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment. 10-Survey of adult behaviour of Culex nigripalpus and other species of Culex (Culex) in South-Eastern Brazil

Relata os resultados obtidos mediante coletas regulares de adultos de Culex (Culex) em ambientes antrópicos do Vale do Ribeira, SP, Brasil, no período de agosto de 1992 a dezembro de 1993. Evidencia a dominância de Culex nigripalpus nas várias coletas efetuadas. Revela claramente a preferência por parte desse mosquito em aumentar sua densidade no ambiente antrópico. Todavia, sua freqüência ao domicílio mostrou-se baixa, revelando fraco grau de sinantropia. Assim sendo, seu papel vetor de arbovirus parece restringir-se à participaçäo no ciclo natural desses agentes infecciosos. Contudo, pode-se considerá-lo como vetor potencial no meio extradomiciliar. Nesse particular, seu papel pode näo ser negligenciável, especialmente no que tange à possibilidade de transmissäo de encefalite de S. Luís, cujo agente já foi assinalado na regiäo

Relación entre mosquitos vectores y aves acuáticas en la transmisión potencial de dos arbovirus / The relationship between mosquito vectors and aquatic birds in the potential transmission of 2 arboviruses

The authors studied for two years the role of the chicks of aquatic birds in the arboviral cycles in coastal lagoons in central Panama in order to determine the relation between Culex (Melanoconion) ocossa and Mansonia (Mansonia) dyari mosquitoes in the transmission and dissemination of the viruses of Saint Louis Encephalitis (SLE) and Venezuelan Equine Encephalitis (VEE). Mosquitoes were captured every fifteen days on two consecutive nights to isolate the virus, using light traps (CDC) and baited traps. The attempts to isolate the virus were made using Vero cell cultures and the determination of antibodies was performed. The results of the serologic tests seem to indicate that four bird species: the ex (?) heron (Bubulcus ibis), the American heron (Casmerodius albus), the spoon-billed duck (Cochlearius cochlearius) and the needle crow (Anhinga anhinga) could function as intermediate hosts in the transmission cycle of SLE. Two species, the ibis (Endocimus albus) and the spoon-billed duck (Cochlearius cochlearius) could also be intermediate hosts of VEE in the coastal lagoons of Panama. The presence of antibodies in chicks could indicate an infection acquired recently, after their birth, in this area. The VEE virus was recovered from blood filled mosquitoes which had fed on a spoon-billed duck probably infected and exposed in a Trinidad #10 trap. No SLE virus was isolated. Other unknown viruses were isolated from mosquitoes selected for these studies, such as C. ocossa and M. dyari. The results obtained with these studies indicate the need for more studies utilizing new field techniques in order to establish a link between SLE and VEE, the vector mosquitoes and the aquatic birds in the coastal lagoons of the area under investigation