Abstract Iridovirus in Culex pipiens was reported for the first time in 2012. Later studies of horizontal transmission were performed, in which an interaction with the parasite Strelkovimermis spiculatus acting as viral vector was recognized. In the present study, we observed aspects of the pathology produced by an invertebrate iridescent virus in laboratory infected immature Cx. pipiens as well as in infected immature Cx. pipiens in the field. In the laboratory infected larvae, the infection and mortality were asynchronous. Signs of infection in larvae exposed to the virus were observed between the second and the fourth days post-exposure in 99% of the cases, while the highest daily record of visible infected larvae (52%) was observed on the third day post exposure. Moreover, 79% of confirmed virus infected larvae died in the first 10 days after exposure. The Median Lethal Time was eight days. Several tissues were found to be infected and the common sites of replication were the fat body, epidermis and epithelial derivatives, such as the imaginal discs and the tracheal epithelium. Moreover, infection in the salivary glands, gastric ceca and posterior gut have not been previously documented on other mosquito iridescent viruses.

Monthly oviposition activity and the seasonal density pattern of Aedes aegypti were studied using larvitraps and ovitraps during a research carried out by the Public Health Ministry of Salta Province, in Tartagal, Aguaray and Salvador Mazza cities, in subtropical Argentina. The A. aegypti population was active in both dry and wet seasons with a peak in March, accordant with the heaviest rainfall. From May to November, the immature population level remained low, but increased in December. Ae. aegypti oviposition activity increased during the fall and summer, when the relative humidity was 60% or higher. Eggs were found in large numbers of ovitraps during all seasons but few eggs were observed in each one during winter. The occurrence and the number of eggs laid were variable when both seasons and cities were compared. The reduction of the population during the winter months was related to the low in the relative humidity of the atmosphere. Significant differences were detected between oviposition occurrences in Tartagal and Aguaray and Salvador Mazza cities, but no differences in the number of eggs were observed. Two factors characterize the seasonal distribution pattern of Ae. aegypti in subtropical Argentina, the absence of a break during winter and an oviposition activity concomitant of the high relative humidity of the atmosphere.

Aedes albifasciatus es un mosquito neotropical ampliamente distribuído en Argentina. Presenta una biología típica de mosquitos de inundación. Sus estadíos larvales se desarrollan en zonas deprimidas que se inundan temporariamente. Durante dos años se realizó un estudio de una población de A. albifasciatus en un área cercana a la Plata, provincia de Buenos Aires, Argentina. Se realizaron muestreos semanales entre mayo de 1996 y abril de 1998. En cada fecha de muestreo se tomaron 100 cucharones de 300 cc. Las eclosiones de mosquitos numéricamente elevadas se produjeron cuando las precipitaciones inundaron el ambiente entre un 90 y 100 % de su capacidad luego de permanecer seco varios días o semanas. En el período estival, las larvas requirieron entre seis y ocho días para alcanzar el estado adulto (temperatura media 24.6 °C en enero y 21.3 °C en febrero). En otoño-invierno, 43 días (temperatura media: 10.6 °C) y en primavera 22 días con una temperatura media de 15.5 °C.

Aedes albifasciatus, a floodwater mosquito, is widely distributed in freshwater habitats in Argentina. At high population densities it is an important pest in urban areas. A two year study was conducted in a natural population of A. albifasciatus around La Plata area, Buenos Aires province, Argentina. The breeding site was weekly sampled from May, 1996 to April, 1998. Immature stages of A. albifasciatus were collected with a standard 300 ml dipper. Each sample unit consisted of 100 dipper. Highest densities of mosquito larvae occurred when the breeding site was flooded among 90 and 100 % of its capacity after remaining dry for several days or weeks. The larvae required between six and eight days to become adult in summer (temperature mean 24.6 °C in January and 21.3 °C in February). In autumn-winter, 43 days (temperature mean 10.6 °C) and in spring 22 days (temperature mean 15.5 °C).