RESUMO
The duration of the gonotrophic cycle and survivorship of Anopheles vestitipennis Dyar & Knab was estimated in 2 malarious areas of Chiapas, Mexico: the Lacandon Forest and the Pacific Ocean Coastal Plain. Blood-engorged females held in an outdoor cage required 2.75 d for egg maturation, and 3.75 d for the duration of the gonotrophic cycle. Duration of the gonotrophic cycle also was estimated by parous-nulliparous dynamics for 20 consecutive days and autocorrelation time-series analysis, and by mark-recapture techniques. These methods depicted differences between the Lacandon Forest (3-d cycle) and the Coastal Plain (2-3 d cycles). Daily survival rates were estimated vertically and were generally higher in the Lacandon Forest (0.68) than in the Coastal Plain (0.45-0.58). The probability of mosquitoes surviving the sporogonic cycle was 10-100 times greater in the Lacandon Forest. The pregravid rate was 8.2%, and 29.3% of females with primary follicles beyond Christophers' stage III had traces of red blood in the gut. The 1st statistic indicated that 8.2% of females required > 1 blood meal for initial egg development, the 2nd statistic indicated that 29.3% of females take > 1 blood meal during a gonotrophic cycle. In summary, the enhanced vectorial role of this species is explained partially by high longevity and multiple blood-feeding habits.
Assuntos
Anopheles/fisiologia , Ecologia , Animais , Feminino , Geografia , Estágios do Ciclo de Vida , Longevidade , Masculino , México , Oviposição , ReproduçãoRESUMO
A blind test of two remote sensing-based models for predicting adult populations of Anopheles albimanus in villages, an indicator of malaria transmission risk, was conducted in southern Chiapas, Mexico. One model was developed using a discriminant analysis approach, while the other was based on regression analysis. The models were developed in 1992 for an area around Tapachula, Chiapas, using Landsat Thematic Mapper (TM) satellite data and geographic information system functions. Using two remotely sensed landscape elements, the discriminant model was able to successfully distinguish between villages with high and low An. albimanus abundance with an overall accuracy of 90%. To test the predictive capability of the models, multitemporal TM data were used to generate a landscape map of the Huixtla area, northwest of Tapachula, where the models were used to predict risk for 40 villages. The resulting predictions were not disclosed until the end of the test. Independently, An. albimanus abundance data were collected in the 40 randomly selected villages for which the predictions had been made. These data were subsequently used to assess the models' accuracies. The discriminant model accurately predicted 79% of the high-abundance villages and 50% of the low-abundance villages, for an overall accuracy of 70%. The regression model correctly identified seven of the 10 villages with the highest mosquito abundance. This test demonstrated that remote sensing-based models generated for one area can be used successfully in another, comparable area.
Assuntos
Anopheles/crescimento & desenvolvimento , Geografia , Insetos Vetores/crescimento & desenvolvimento , Malária/transmissão , Animais , Análise Discriminante , Humanos , Malária/epidemiologia , México/epidemiologia , Análise Multivariada , Análise de Regressão , Fatores de Risco , Comunicações Via SatéliteRESUMO
Biting activity and population genetic studies of the malaria vector Anopheles vestitipennis were conducted in southern México. Three subpopulations were collected from 2 villages; 2 subpopulations were from the same village, one on human bait and one with an animal-baited trap; the third was collected from a cattle corral in the 2nd village (280 km away SSE). The anthropophilic subpopulation had steady activity with 61% of bites occurring before midnight, significantly different from those of the 2 zoophilic subpopulations, which had 78-82% of bites before midnight and 2 biting peaks, one at 1900-2100 h and the other at 0400-0500 h. Isozyme analysis (13 enzymes) of these subpopulations indicated that differences between the 2 sympatric subpopulations (D = 0.07), collected using 2 different methods, were greater than that between the 2 allopatric ones (D = 0.03). These studies suggest the existence of 2 genetically different subpopulations of An. vestitipennis with specific host preferences.
Assuntos
Anopheles/genética , Alelos , Animais , Bovinos , Humanos , Mordeduras e Picadas de Insetos , Isoenzimas/genética , MéxicoRESUMO
Samples of Anopheles freeborni s.1. were collected from areas of New Mexico where malaria had once been common and sporozoites had been isolated from this species. Specimens were identified by analysis of polytene chromosome banding patterns and by specific rDNA fragments generated through the polymerase chain reaction. All samples collected in New Mexico were identified as An. hermsi, which was the probable vector of malaria in this region during the early 20th century.