Records of Aedes albopictus, Ae. aegypti and Ae. triseriatus from the U.S. Air Force ovitrapping program--1989

During 1989, ovitrapping was conducted by 36 U.S. Air Force bases, Ft. Sam Houston, TX, and the San Antonio Metropolitan Health District. Eleven organizations were positive for Aedes albopictus; the collection of Ae. albopictus at Arnold Air Force Base, TN, is a new record for Coffee County. Ten organizations were positive for Ae. aegypti; 18 were positive for Ae. triseriatus.     

Cross-breeding of Aedes (S.) polynesiensis Marks with an autogenous species of the A. scutellaris group

An autogenous species belonging to the Aedes (Stegomyia) scutellaris subgroup was found on the island of Tafahi, Kingdom of Tonga. A subcolony was established at Johns Hopkins University, Baltimore, Md., USA, where cross-breeding experiments were conducted with the Samoan strain of A. polynesiensis. The cross between Tafahi females and A. polynesiensis males produced viable hybrid progeny, which were inbred through five generations. The reciprocal cross was not successful. F₁ Tafahi × A. polynesiensis hybrid males were backcrossed successfully to Tafahi females, but of the many eggs produced by backcrossing these F₁TP males to A. polynesiensis females, only 0.7% hatched. Of the eggs produced by the F₂TP male × A. polynesiensis female backcross, about 7% were viable. The results indicate a close genetic relationship between the Tafahi species and A. polynesiensis. The one-directional compatibility observed suggests the existence of cytoplasmic factors for sterility, which might eventually be useful in the control of members of the A. scutellaris complex.     

Aedes aegypti (L.) and Aedes albopictus (Skuse) in Singapore City. 4. Competition between species

There is a current belief stemming from statements made in the literature that Ae. aegypti is displacing Ae. albopictus in a number of cities of South-East Asia and in Calcutta, India. A critical review of these works showed that either the observations were inconclusive or the methods of collection were biased for one or the other species.     

Conservation of the names Aedes albothorax, Ae. circumluteolus, and Ae. mcintoshi

As a result of action by the International Commission on Zoological Nomenclature, the specific names Aedes albothorax (Theobald, 1907), Ae. circumluteolus (Theobald, 1908), and Ae. mcintoshi Huang, 1985, are conserved for common African mosquitoes; a neotype for albothorax is designated; and the specific name Banksinella pallid Theobald, 1907, is suppressed.     

Adult Aedes albopictus and Ae. scapularis behavior (Diptera: Culicidae in Southeastern Brazil

OBJECTIVE: Aedes albopictus and Ae. scapularis were found living together in the Pedrinhas Village, Southeastern of S?o Paulo State, Brazil. This finding was a good opportunity to make observations about the mosquitoes' behavior. METHODS: From October 1996 to January 2000 observations were carried out through systematic collections with human bait, environment aspirations and Shannon trap utilization. Synanthropy was estimated by the Nuorteva index and synanthropic ratios. RESULTS: The 87 collections with human bait yield 872 females adults. Williams' means, multiplied by 100, were 118 and 21 for Ae. albopictus at the 7 AM-6PM and 6PM-8PM hours, respectively, 100 and 106 for Ae. scapularis at the same timetable but there was an evening peak. Through environmental aspirations, a total of 1,124 adults samples was collected, 226 Ae. albopictus samples and 898 Ae. scapularis samples. The period between the months of January-May was the one with higher yield for both mosquitoes. There was no Ae. albopictus in the Shannon trap operated inside the adjacent forest. Regarding the sinanthropy, that culicid showed the higher index values, while Ae. scapularis was ubiquitous. CONCLUSIONS: The data obtained allows to form the hypothesis that Ae. scapularis females may have a diapause phase in the resting places and after that period they will retake the hematophagy habit. That might explain the higher activity at the human bait during the dry months, corresponding to the period of July-October.     

Aedes aegypti (L.) and Aedes albopictus (Skuse) in Singapore City. 3. Population fluctuations

Fluctuations in the adult Ae. aegypti and Ae. albopictus populations and their relationship to rainfall were studied by weekly collections from a number of stations in the city. Aedes aegypti populations generally fluctuated with the rainfall, with multiple peaks, except in the middle of the year when there was no increase in rainfall at the time of the peak in population. It is suggested that other regulating factors, in addition to rainfall, also determine the fluctuations of this species. Aedes albopictus also fluctuated, with three peaks in a year, and these bore a close relationship to rainfall.     

Aedes aegypti (L.) and Aedes albopictus (Skuse) in Singapore City. 2. Larval habitats

Detailed information on the breeding habitats of Ae. aegypti and Ae. albopictus is necessary when planning programmes for their control. The larval habitats of the two species in 10 city areas were counted and classified according to type, frequency of occurrence, location, and function. Of all the breeding habitats recorded 95% were domestic containers. The most common Ae. aegypti breeding habitats were ant traps, earthenware jars, bowls, tanks, tin cans, and drums, ant traps being the most common indoors and earthenware jars the most common out doors. Breeding habitats for Ae. albopictus were commonly found in earthen ware jars, tin cans, ant traps, rubber tires, bowls, and drums; ant traps were the most common indoor habitat and tin cans were most common outdoors.     

Aedes aegypti (L.) and Aedes albopictus (Skuse) in Singapore City. 1. Distribution and density

The distribution and density of Ae. aegypti and Ae. albopictus in Singapore were assessed from extensive larval surveys carried out from 1966 to 1968 to evaluate their respective roles in the epidemiology of dengue haemorrhagic fever and to study their ecology in the urban areas. Ten urban areas where the majority of dengue haemorrhagic fever cases occurred were surveyed.     

Variation in tarsal claw morphology and the identification of Aedes (Stegomyia) demeilloni/segermanae and Aedes (Stegomyia) simpsoni/bromeliae (Diptera: Culicidae) in South Africa.

Individuals in families of Aedes (Stegomyia) mosquitoes reared from females collected at Kloof, KwaZulu-Natal, were identified as Aedes demeilloni or Aedes segermanae or were indeterminate because tarsal claw morphology, the distinguishing character, varied. Similarly, Aedes (Stegomyia) simpsoni and Aedes (Stegomyia) bromeliae reared from ovitraps exposed at Ndumu, northern KwaZulu-Natal, showed variation in tarsal claw morphology. Variation existed between tarsal claws on individual specimens, which made identification difficult at Ndumu, indicating that tarsal claws may not be taxonomically significant.     

Aedes aegypti (L.) and Aedes albopictus (Skuse) in Singapore City. 5. Observations in relation to dengue haemorrhagic fever

Dengue haemorrhagic fever in Singapore was a disease of the urban human population, with concentrations of cases occurring in areas of high population density. Mosquito surveys revealed that these areas also had high population densities of Ae. aegypti and Ae. albopictus.     

Hybridization between Aedes simpsoni and Aedes woodi with observations on the genetic basis of morphological differences

The public health importance of the genus Aedes makes it imperative that a better understanding of the genetic differences and isolating barriers between the species be developed. Aedes simpsoni and Aedes woodi from near Dar es Salaam, Tanzania, were used in this investigation. Analysis of F₁, F₂, and backcross progeny obtained from forced matings indicates that single factors form the genetic basis of some of the differences between the two species. There is evidence that Ae. simpsoni and Ae. woodi are separated by both premating and postmating reproductive isolating mechanisms.     

海南省埃及伊蚊和白纹伊蚊对常用杀虫剂的敏感性测定

目的了解海南省原登革热流行区埃及伊蚊和白纹伊蚊对常用杀虫剂的敏感性。方法采用幼虫浸渍法,测定蚊虫对常用杀虫剂的抗性系数。结果埃及伊蚊对溴氰菊酯抗性系数为2.04～2.82,而三亚市埃及伊蚊对高效氯氰菊酯的抗性系数为3.76。白纹伊蚊对溴氰菊酯的抗性系数为2.40～3.60,而海口市白纹伊蚊对仲丁威和残杀威抗性系数分别为2.63和2.07。结论海南省原登革热流行区埃及伊蚊和白纹伊蚊对供试杀虫剂敏感性下降。     

Virulence factor-activity relationships (VFAR) with specific emphasis on Aeromonas species (spp.)

The human population most commonly inflicted with Aeromonas infection includes young children, the elderly and immunocompromised individuals. Importantly, the isolation rate of Aeromonas species from children suffering from diarrhea is similar in developing and developed countries. It is becoming clear that only a small subset of Aeromonas species belonging to a particular hybridization group causes disease in humans. Human infections with this pathogen occur by consuming contaminated food and water. Aeromonas species were isolated from wounds of patients during the tsunami in southern Thailand. Further, increased numbers of this pathogen were recovered from floodwater samples during Hurricane Katrina in New Orleans. Among various species of Aeromonas, A. hydrophila, A. caviae and A. veronii biovar sobria are mainly responsible for causing disease in humans. Our laboratory has isolated various virulence factors from a diarrheal isolate SSU of A. hydrophila and molecularly characterized them. In addition to various virulence factors produced by Aeromonas species, the status of the immune system plays an important role in inducing disease by this pathogen in the host. Taken together, we have made significant advances in better understanding the pathogenesis of Aeromonas infections, which will help in differentiating pathogenic from non-pathogenic aeromonads. This review covers virulence aspects of a clinical isolate of A. hydrophila.     

Relative abundance of tree hole-breeding mosquitoes in Boone County, Missouri, USA, with emphasis on the vector potential of Aedes triseriatus for canine heartworm, Dirofilaria immitis (Spirurida: Filariidae)

Aedes (Protomacleaya) triseriatus currently shares its habitat in the USA with the introduced species Aedes (Finlaya) japonicus and Aedes (Stegomyia) albopictus. In the late 1980s, before the introduction of these 2 species, Ae. triseriatus was the dominant tree hole- and artificial container-breeding mosquito in central Missouri. Aedes triseriatus represented 89% of the mosquito immatures collected from water-filled tree holes and artificial containers at 3 forested field sites in central Missouri, from May to October, 1986 to 1988. Laboratory-reared female Ae. triseriatus were able to support larval development of Dirofilaria immitis (canine heartworm) to the infective 3rd larval stage. A blood meal from a microfilaremic Collie-mix dog was sufficient to infect adult female mosquitoes, indicating that Ae. triseriatus is a possible vector of canine heartworm in central Missouri. Confirmation of the vector status of this species depends on the yet-to-be observed transmission of D. immitis by Ae. triseriatus in the field, possibly by experimental infection of dogs by wild-caught mosquitoes. Defining the role of this species in epizootic outbreaks could contribute toward accurate risk assessment as the abundance of Ae. triseriatus increases and decreases in response to the success of Ae. albopictus, Ae. japonicus, or other introduced container-breeding mosquitoes.     

Cell lines from larvae of Aedes (Stegomyia) malayensis Colless and Aedes (S) pseudoscutellaris (Theobald) and their infection with some arboviruses

The establishment of 2 cell lines from first stage larvae of the mosquitoes, Aedes malayensis and Aedes pseudoscutellaris is described. The cells of the A. malayensis line are diploid while those of A. pseudoscutellaris are predominantly polyploid.West Nile and Japanese B encephalitis viruses produced a cytopathic effect (CPE) in the A. malayensis cells. Both these viruses and Dengue-2 virus also produced a cytopathic effect in the A. pseudoscutellaris cells. There was some evidence that the CPE was influenced by the nature of the container. A. malayensis cells of early subcultures grown in Falcon plastic flasks formed large syncytia while those of later subcultures infected under identical conditions produced only small syncytia. Cells of the A. malayensis line grown on glass did not show any cytopathic response in early subcultures, but in cells of higher subcultures grown on glass, the viruses produced a definite CPE presenting as degenerate clumps of cells and floating single cells. It is suggested that the different result is due to continual adaptation of the cells to the culture conditions in the early stages.Cells of the A. pseudoscutellaris line, following infection with viruses formed syncytia, clearly visible on plastic surfaces, but less obvious on glass. An unadapted strain of Dengue-2 in infected human serum produced syncytia in the cells, but did not produce any plaques in a stable line in pig kidney cells. The infected cultures recovered after some days and formed healthy monolayers. Such cells were subcultured without showing any cytopathic response, but continued to produce virus.