Analysis of the genetic variability and structure of Ochlerotatus taeniorhynchus (Diptera: Culicidae) populations from the Colombian Atlantic coast on the basis of random amplified polymorphic DNA markers.

Ochlerotatus taeniorhynchus (Diptera: Culicidae) is a mosquito, which is an efficient vector of the virus causing epidemic-epizootic Venezuelan equine encephalitis in Colombia. This study used 9 random amplified polymorphic DNA (RAPD) markers to analyze the mosquito's genetic variability and genetic structure of 122 specimens in 7 populations from the Colombian Atlantic coast. Assuming that all loci were in Hardy-Weinberg equilibrium, diversity statistics and analyses were performed. The average number of amplified fragments for each primer was 8.3, and the size of these fragments ranged from 350 to 3600 bp. The expected average heterozygosity was 0.358 ± 0.103. The genetic heterogeneity among the populations studied was small (GST = 0.05 ± 0.01); meanwhile, the gene flow estimates (Nm = 7.32 ± 1.35) were high. In an identical way, the Nei's genetic distances obtained yielded very small values amongst the populations that were studied in this Colombian region. Furthermore, a spatial autocorrelation analysis with Moran's I index revealed a very weak, or inexistent, spatial genetic structure among these populations. The comparison of these results with those performed for other markers (isoenzymes and microsatellites) in populations of this same mosquito from the Colombian Atlantic coast was discussed. The results of our RAPD analysis showed scarce genetic differentiation among the mosquito populations on the Colombian Atlantic coast, which was probably determined by high gene flow levels.

Synanthropy of Calliphoridae and Sarcophagidae (Diptera) in Bogotá, Colombia.

Calliphoridae and Sarcophagidae have medical and forensic importance. Species of these families are the first insects colonizing corpses and are, therefore, useful in establishing postmortem interval and as indicators in corpse transfer. The synanthropic index (SI) measures the relation of dipteran species with human settlements. Our main objective was to determine the synanthropic index of these families during the rainy and dry seasons in Bogotá. Captures were carried out using traps with baits (beef liver) in three zones (urban, rural, and forest areas). In the family Calliphoridae, the most abundant species were Calliphora vicina (Robineau-Desvoidy) with a sinanthropy index (SI) of +83.1, followed by Lucilia sericata (Meigen) (SI = +92.2) and Compsomyiops verena (Walker) (SI = +42.0). Calliphora nigribasis (Macquart) was not associated with human settlements, while Sarconesiopsis magellanica (Le Guillou) was present in the three zones and considered hemisynanthropic (SI = +19.0). Roraimomusca roraima (Townsend) was reported for the first time in Bogotá and was a non-synanthropic species (SI = -36.0). On the other hand, in Sarcophagidae, three species were collected: Ravinia rufipes (Twonsend), Ravinia colombiana (Lopes), and Boettcheria sp1, which were abundant in the rural and forest zones, the first having a dual characterization as synanthropic and hemisynanthropic, while the other two were hemisynanthropic. Our data showed differences in the association of Calliphoridae species with the three environments, whereas Sarcophagidae were distributed in locations with a lower human impact.

A new continuous cell line from the mosquito Psorophora confinnis (Diptera: Culicidae) and its susceptibility to infections with some arboviruses.

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.

Brain cell karyotype of the phlebotomine sand fly Lutzomyia shannoni (Dyar) (Diptera: Psychodidae).

The brain cell karyotype of New World sand fly Lutzomyia shannoni was described. This species has four pairs of chromosomes, 2N=8, with one pair of heteromorphic chromosomes.

Establishment and characterization of a new continuous cell line from Lutzomyia longipalpis (Diptera: psychodidae) and its susceptibility to infections with arboviruses and Leishmania chagasi.

Embryonic tissue explants of the sand fly Lutzomyia longipalpis (Lutz & Neiva 1912) the main vector of Leishmania chagasi (Cunha and Chagas), were used to obtain a continuous cell line (Lulo). The tissues were seeded in MM/VP12 medium and these were incubated at 28 masculineC. The first subculture was obtained 45 days after explanting and 96 passages have been made to date. Lulo is composed of epithelioid cells, showed a 0.04 generations/hour exponential growth rate and population doubling time at 24.7 h. The cell line isoenzymatic profiles were determined by using PGI, PGM, MPI and 6-PGDH systems, coinciding with patterns obtained from the same species and colony's pupae and adults. The species karyotype characteristics were recognized (2n = 8), in which pair 1 is subtelocentric and pairs 2, 3 and 4 are metacentric. Lulo was free from bacterial, fungal, mycoplasmic and viral infection. Susceptibility to five arbovirus was determined, the same as Lulo interaction with Leishmania promastigotes.

Establishment and characterization of a cell line from the mosquito Anopheles albimanus (Diptera: Culicidae).

A new cell line designated LSB-AA695BB, was established from embryos of the mosquito Anopheles albimanus. The primary culture was initiated in April, 1995, and the first passage was made 48 days later. Serial subcultures of the cells have been carried through 90 passage from Abril 1995 to February 1996. The cells were grown at 28 degrees C in MK/VP12 medium, supplemented with 20% fetal bovine serum: the pH tolerance ranged between 6.8 to 7.0. The cells have also been adapted to MM/VP12 medium under the same pH, temperature and serum concentration. The majority of the cells were a fibroblast-type. Isozyme characterization showed a pattern similar to that of An. albimanus pupae and adults but distinct from Ae. taeniorhynchus and Ae. albopictus (C6/36) mosquito cell lines. The culture was shown to be free of mycoplasma, bacteria and fungi. Microsporidia contamination of transovarial transmission was controlled with 6.0 micrograms/ml of albendazole.

Establecimiento y mantenimiento de una colonia de Aedes taeniorhynchus, Wiedemann, 1821 (Díptera: Culicidae) cepa Barranquilla, Colombia / Establishment and maintainance of a colony of Aedes taeniorhynchus, Wiedemann, 1821 (Diptera: Culicidae) strain Barranquilla, Colombia

Se estableció una colonia del mosquito Aedes taeniorhynchus, eficiente vector del virus de la encefalitis equina venezolana, tipo epidemo-epizoótico, a partir de formas adultas, recolectados en regiones cercanas a Barranquilla, Atlántico (Colombia). Se estudiaron algunos aspectos de la biología de este insecto (ciclo de vida y logevidad), elaboración de tablas de vida e igualmente se maximizaron algunos parámetros físicos, ambientales y nutricionales que garantizan el mantenimiento y la continuidad de la especie en condiciones de laboratorio. Esta colonia fue establecida con el objeto de proporcionar la materia prima biológica para los explantes de tejidos embrionarios que se han venido utilizando para establecer líneas celulares de crecimiento continuo