RESUMEN
In most of the 130 islands of French Polynesia, the stenotopic mosquitoes Aedes aegypti (the main local vector for the viruses causing dengue) and Aedes polynesiensis (the main local vector of Wuchereria bancrofti) share many breeding sites in water containers such as discarded cans, coconut shells, buckets and water-storage pots and drums. In addition to selective application of insecticides, non-polluting methods of controlling these mosquitoes have been evaluated during the last decade in two main ecological situations: (1) villages, where Aedes breeding sites are typically peridomestic; and (2) flooded burrows of land crabs, the major source of Ae. polynesiensis throughout the South Pacific region. Large-scale trials of biological control agents, such as mosquito fish (Gambusia affinis and Poecilia reticulata) and copepods (Mesocyclops aspericornis), and of integrated-control strategies have demonstrated the efficacy of certain techniques and control agents against the target Aedes populations in some village situations. Generally, mechanical methods (the use of layers of polystyrene beads against mosquito larvae and pupae, and screening against adult mosquitoes) were more efficient than use of the biological control agents. By integrating several methods of control, mosquito densities (as measured by human-bait collections and larval surveys) were reduced significantly compared with the results of concurrent sampling from untreated villages, and control remained effective for months after the interventions ceased. In land-crab burrows, the first attempts to control Aedes larvae used bacterial agents (Bacillus thuringiensis) and predatory copepods gave disappointing results. Mesocyclops aspericornis could be an effective control agent if the burrows were constantly flooded, but most burrows dry out and refill periodically, so copepod populations do not survive. As it proved difficult to reach all corners of the long sinuous burrows with any control agent, larvicidal (chlorpyrifos-methyl) baits were developed for foraging crabs to carry into their burrows. This novel technique proved to be effective and could become the method of choice for treating crab burrows. Further research is underway to find the optimum (biological or chemical) larvicidal ingredient for the crab bait. Despite the ecological and logistical challenges of controlling the Aedes vectors of the dengue viruses and W. bancrofti in so many scattered islands, the French Polynesian experience indicates that relatively simple methods can be integrated and applied effectively and economically. Operationally, however, success also depends on a strong political commitment and on at-risk communities that are sufficiently motivated to maintain a good level of Aedes control.
Asunto(s)
Aedes/parasitología , Virus del Dengue , Dengue/prevención & control , Vectores de Enfermedades , Filariasis Linfática/prevención & control , Control de Mosquitos/métodos , Wuchereria bancrofti , Adulto , Aedes/virología , Animales , Copépodos , Ciprinodontiformes , Dengue/epidemiología , Dengue/transmisión , Filariasis Linfática/epidemiología , Filariasis Linfática/transmisión , Educación en Salud , Humanos , Larva , Polinesia/epidemiología , Salud RuralRESUMEN
High density of haematophagous blackflies on Nuku-Hiva Island (Marquesas archipelago, French Polynesia) is a handicap to its optimal development. The present study contains observations from many sampling sites to examine aggressive periods of Simulium buissoni Roubaud, 1906. Density of aggressive females is very high, principally in highly irrigated sites of the island. Biting rates show low variation between days, and a diurnal activity, with a poorly pronounced circum-meridian maximum. Parity rates show great variation between sampling stations, but are lowest during the day. A hypothesis of greater spatial dispersion of nulliparous females allows explanation of much of the observed variation. Sampling in and out of a house shows exophily of blackflies. Proportion of parous females is greater in the house. Data collected over a long period show that earlier densities were greater than recent ones. Perturbation of the environment is probably the basis of this decrease.
Asunto(s)
Conducta Alimentaria/fisiología , Simuliidae/fisiología , Animales , Ritmo Circadiano , Ambiente , Femenino , Geografía , Vivienda , Humanos , Mordeduras y Picaduras de Insectos/epidemiología , Periodicidad , Polinesia , Densidad de Población , Reproducción , Estaciones del Año , Especificidad de la EspecieRESUMEN
Simulium sechani Craig & Fossati, 1995 was recently found for the first time in a part of Nuku-Hiva Island. This species coexists with Simulim buissoni Roubaud 1906, the dominant species, and always regarded as the main biting fly on the island. The problem is that optimisation of control operations needs a good knowledge of targets. The unknown female of S. sechani is the reason of this study. This study used samples collected before the description of S. sechani to try to correlate its geographical extent with easy to use biometrical parameters, and then give a first look at the possibilities of determination of adult females. Parameters used are: the numbers of maxillary and mandibular teeth, the dimension of the third antenna article and the number of apical hairs, the width and depth of the ventral plate space, and the number of hairs on the radial vein of the wing. Analysis of frequency distributions in relation with sampling sites and trapping hosts did not allow us to find convenient diagnosis characters, but contributed to new questions about isolation of insect populations in valleys and hosts usually used.
Asunto(s)
Simuliidae/anatomía & histología , Simuliidae/clasificación , Animales , Enfermedades de los Perros/parasitología , Perros , Infestaciones Ectoparasitarias/fisiopatología , Infestaciones Ectoparasitarias/veterinaria , Femenino , Geografía , Enfermedades de los Caballos/parasitología , Caballos , Humanos , Masculino , Islas del Pacífico , Polinesia , Análisis para Determinación del Sexo , Porcinos , Enfermedades de los Porcinos/parasitologíaRESUMEN
In order to construct a cDNA library from third-stage larvae (L3) of Wuchereria bancrofti var. pacifica, the Parafilm membrane feeding method is proposed for the oral infection of Aedes polynesiensis. Heparinized blood supplemented with 5.10(-3) M ATP was put in the feeder with carbon dioxide provided as additional phagostimulant. The results of this artificial infection feeding method were compared with those obtained when mosquitoes fed directly on the forearm of a microfilaremic patient. The number of females feeding through the artificial membrane was smaller than on the patient's forearm (32.1 vs. 84.8%). The mean number of L3s obtained per female was not statistically different between the 2 feeding methods; however, the total number of L3s obtained from 100 females allowed to feed in each group was twice as high in the natural feeding method.
Asunto(s)
Aedes/parasitología , Entomología/métodos , Insectos Vectores , Membranas Artificiales , Parafina , Wuchereria bancrofti , Animales , Conducta Alimentaria , Femenino , Interacciones Huésped-ParásitosRESUMEN
A method to determine the susceptibility of Mesocyclops aspericornis to insecticides is proposed. Tests were carried out by placing adults females in 100 ml of insecticide solution at 3 temperatures (20 degrees C, 25 degrees C, 30 degrees C). Mortality was scored 24 h after treatment. The results show a low variability of the insecticide effectiveness at these temperatures.