- Role of Habitat Components on the Dynamics of Aedes albopictus (Diptera: Culicidae) from New Orleans
Comiskey, NM; Lowrie, RC Jr; Wesson, DM
Journal of Medical Entomology [J. Med. Entomol.], vol. 36, no. 3, pp. 313-320, May 1999
Monthly sampling of tire pile populations of Aedes albopictus (Skuse) in Orleans Parish, New Orleans, LA, was done in 1995 to determine prevalence of ascogregarine parasites and changes in wing length. Prevalence of Ascogregarina taiwanensis (Lien & Levine) infection was 100% in midsummer and decreased in the fall and spring (60-70%). Wing lengths were longest in the spring and fall and shortest in midsummer. We evaluated the effect of A. taiwanensis infections under high and deficient levels of leaf litter nutrients on mortality, development time, wing length, and reproductive potential of a New Orleans strain of Ae. albopictus. Parasitism and deficient nutrients caused a 35% increase in the rate of larval mortality and significantly extended the development time of females. Parasitized adults were 5% smaller and produced 23% fewer eggs than unparasitized siblings. In addition, abnormal Malpighian tubule morphology and melanization of ascogregarines were seen in adults from nutrient-deficient microcosms. We conclude that ascogregarine infections affect the dynamics of Ae. albopictus by increasing the mortality of immature stages when nutrients supplies are scarce, and by decreasing the reproductive capacity of females under high nutrient conditions.
- Density Dependence in Larval Aedes albopictus (Diptera: Culicidae)
Journal of Medical Entomology [J. Med. Entomol.], vol. 35, no. 5, pp. 825-829, Sep 1998
Aedes albopictus (Skuse) is expanding its distribution in the United States and elsewhere, and a better understanding of its population regulation is needed. A field experiment under seminatural conditions determined that density had a negative effect and food level a positive effect on immature survival, duration of development, and female size at emergence. A summary index (r') indicated that population growth also depended on density and food availability. These data can be used to estimate the relationships needed in the development of mathematical models for Ae. albopictus.
- Species introduction and replacement among mosquitoes: Interspecific resource competition or apparent competition?
Ecology, vol. 79, no. 1, pp. 255-268, Jan 1998
Mechanisms by which an introduced container-dwelling mosquito, Aedes albopictus, may cause declines in a resident container-dwelling mosquito, Aedes aegypti, in South Florida were tested using a combination of field experiments and field observations. Field experiment 1 tested which species has a competitive advantage as larvae developing in water-filled tires. Densities and availability of resources (leaf litter, which is a substrate for microorganisms fed upon by larvae) were manipulated in a factorial design. Contrary to previous laboratory experiments, A. albopictus was clearly the superior competitor in this tire environment, maintaining positive population growth at higher combined density and lower per capita resource availability than did A. aegypti. The primary determinant of success in this experiment was survivorship to adulthood, and A. aegypti only survived well in this environment when raised alone at low density, with high resource availability. Field experiment 2 tested whether this advantage for A. albopictus resulted from apparent competition mediated by shared protozoan parasites in the genus Ascogregarina. In field experiment 2, A. albopictus larvae had moderate to high levels of parasitism, but A. aegypti larvae were virtually free from Ascogregarina in all experimental tires, implying that Ascogregarina played little or no role in producing the advantage for A. albopictus in field experiment 1. Thus, apparent competition does not appear to be necessary to account for the replacement of A. aegypti by A. albopictus. As a first step toward understanding variation in the outcome of this invasion, numbers of Aedes immatures and masses of adults from field collected pupae (indicators of the intensity of competition) were compared for three sites with known histories of invasion by A. albopictus and decline of A. aegypti. Differences among sites in both number of Aedes per container and masses of adults of both species were consistent with the hypothesis that intensity of competition varies among sites, and suggest that A. aegypti persists only at sites where interspecific competition is less intense. Resource competition among larvae appears to be sufficient to account for replacement of A. aegypti by A. albopictus in suburban and rural areas of South Florida, which may have been marginal habitats for A. aegypti.
- Spread of Aedes albopictus and decline of Ae. aegypti (Diptera: Culicidae) in Florida
O'Meara, GF; Evans, LF Jr; Gettman, AD; Cuda, JP
Journal of Medical Entomology [J. MED. ENTOMOL.], vol. 32, no. 4, pp. 554-562, 1995
Waste tires and other types of artificial containers were sampled for immature Aedes to monitor changes in the occurrence of Aedes aegypti (L.) and Aedes albopictus (Skuse) in Florida. The initial invasion and spread of Ae. albopictus in Florida occurred in the northern part of Florida. Throughout this region, major declines in the abundance of Ae. aegypti have been associated with the expansion of Ae. albopictus in both urban and rural areas. Generally, the same results have occurred in central Florida, but at some urban locations Ae. aegypti has remained a common mosquito long after the arrival of Ae. albopictus. In southeastern Florida, Ae. aegypti is currently the dominant container-inhabiting Aedes in urban areas, whereas sites dominated by Ae. albopictus are in rural settings or in undeveloped tracts of land within urban or suburban areas. At some locations, immature Ae. albopictus were found in the same containers with another exotic mosquito, Ae. bahamensis Berlin. The persistence of thriving Ae. aegypti populations in urban areas of southern Florida indicates that Ae. albopictus might not become the dominant container Aedes in these habitats, at least not to the extent that it has in the northern part of the state.
- Aedes albopictus (Diptera: Culicidae) eggs: Field survivorship during northern Indiana winters
Hanson, SM; Craig, GB Jr*
Journal of Medical Entomology [J. MED. ENTOMOL.], vol. 32, no. 5, pp. 599-604, 1995
Aedes albopictus (Skuse) is an Asian mosquito that recently has colonized North America via used tire transport. Temperate Ae. albopictus populations overwinter as diapausing eggs, but tropical populations cannot diapause. Eggs of tropical (SABAH) and temperate (INDY) Ae. albopictus were obtained in diapause-inducing conditions and placed inside a scrap tire to monitor overwintering survival in northern Indiana during the winters of 1989-1990 and 1990-1991. Diapause eggs of Ae. triseriatus (Say), a native North American mosquito, were included for comparison. Tropical Ae. albopictus from Malaysia did not survive either winter. Temperate Ae. albopictus from Indianapolis, IN, did not survive the winter of 1989-1990, but 78% survived the winter of 1990-1991. In contrast, 92 and 96% of Ae. triseriatus survived the winters of 1989-1990 and 1990-1991, respectively. Neither mean temperature nor absolute minimum temperature (a winter's lowest temperature) accurately predicted Ae. albopictus overwintering survivorship in the field. The possible effect of snow and other insulating materials on the overwintering survivorship of Ae. albopictus eggs is discussed.
- Survey of container-inhabiting mosquitoes in Clemson, South Carolina, with emphasis on Aedes albopictus
Richardson, JH; Barton, WE; Williams, DC
Journal of the American Mosquito Control Association [J. AM. MOSQ. CONTROL ASSOC.], vol. 11, no. 4, pp. 396-400, 1995
A total of 530 oviposition trap samples were collected within a 10-km radius of Clemson University between March 30 and October 19, 1993. From 19,664 larvae reared from collected eggs, 7 species were identified: Aedes albopictus (89%), Ae. triseriatus (6.5%), Culex restuans (2.7%), Cx. territans (0.6%), Cx. pipiens complex (0.7%), Toxorhynchites rutilus septentrionalis (0.2%), and Orthopodomyia signifera (0.1%). This is the first record of Ae. albopictus in Clemson. Aedes aegypti was not found. Of the 41 ovitrap locations, 100% were positive for Ae. albopictus.
- Blood hosts of Aedes albopictus in the United States
Niebylski, ML; Savage, HM; Nasci, RS; Craig, GB Jr
Journal of the American Mosquito Control Association [J. AM. MOSQ. CONTROL ASSOC.], vol. 10, no. 3, pp. 447-450, 1994
Bloodfed Aedes albopictus were collected during 1989-91 by vacuum aspirator from rural and urban study sites in Missouri, Florida, Indiana, Illinois, and Louisiana. Blood hosts identified by ELISA and precipitin tests were rabbit (n = 91). Rattus sp. (n = 69), dog (n = 14), unidentified mammal (n = 14), cow (n = 13), human (n = 10), deer (n = 10), sciurid (n = 7), turtle (n = 5), murid other than Rattus sp. (n = 4), raccoon (n = 3), passeriform bird (n = 3), and cat (n = 2). As an opportunistic bloodfeeder, Ae. albopictus may be a potential vector of domestic arboviruses and a nuisance pest where infestations occur.
- The community ecology of Aedes egg hatching: Implications for a mosquito invasion.
Edgerly, JS; Willey, MS; Livdahl, TP
Ecological Entomology [ECOL. ENTOMOL.], vol. 18, no. 2, pp. 123-128, 1993
A recently introduced treehole mosquito from Asia, Aedes albopictus , is spreading throughout eastern North America, especially in tyre-refuse piles. Previous studies have identified inhibitory effects of larvae on egg hatch as a potential population regulatory mechanism within Aedes . Larva-egg interactions may also occur between species. This experiment assesses the ability of larvae of A. albopictus and two possible competitors in North America, A. triseriatus and A. aegypti , to suppress hatching of conspecific and congeneric eggs. We exposed eggs of each species to varying combinations of larval species and density for 24 h and assessed subsequent hatch rates. Aedes albopictus eggs exhibited the lowest level of inhibition when exposed to high larval densities; moreover, at the lowest larval density they imposed the most intense interspecific hatch inhibition. Discretionary hatching in response to larval density may influence community composition by promoting the spread of A. albopictus , perhaps even leading to its dominance within North American Aedes communities.
- Distribution, abundance and bionomics of Aedes albopictus in southern Texas.
Journal of the American Mosquito Control Association [J. AM. MOSQ. CONTROL ASSOC.], vol. 9, no. 3, pp. 367-369, 1993
A survey was conducted for Aedes albopictus in southern Texas during the summer of 1992. Thirty-five new county records were added to the distribution of this imported mosquito in Texas. Aedes albopictus was widely distributed throughout the ecological regions in the survey area, but is abundance decreased in counties adjacent to the Rio Grade River. However, these counties had high densities of Aedes aegypti .
- Importation of Aedes albopictus and other exotic mosquito species into the United States in used tires from Asia.
Craven, RB; Eliason, DA; Francy, DB; Reiter, P; Campos, EG; Jakob, WL; Smith, GC; Bozzi, CJ; Moore, CG; et al.
Journal of the American Mosquito Control Association [J. AM. MOSQ. CONTROL ASSOC.], vol. 4, no. 2, pp. 138-142, 1988
79 seagoing containers and their contents of 22,051 used tires were inspected for adult mosquitoes as well as eggs and larvae. Of the total inspected, 5,507 tires (25%) contained significant amounts of water. No adults or eggs were found. Fifteen tires contained mosquito larvae that were identified as Ae. albopictus, Ae. togoi, Culex pipiens complex, Tripteroides bambusa and Uranotaenia bimaculata . The infestation rate for all species was 6.8 infested tires per 10,000 tires (wet and dry) inspected. Aedes albopictus larvae were most frequently collected, occurring at a rate of 20 infested wet tires per 10,000 inspected.
- Integrated control of the dengue vector Aedes aegypti in Liu-Chiu Village, Ping-Tung County, Taiwan
Wang, CH; Chang, NT; Wu, HH; Ho, CM
Journal of the American Mosquito Control Association [J. Am. Mosq. Control Assoc.], vol. 16, no. 2, pp. 93-99, Jun 2000
Because of an inadequate supply of potable water, villagers of Small Liu-Chiu Isle, Ping-Tung County, Taiwan, store water in containers supporting a large population of Aedes aegypti. In 1989-96, integrated control measures against Ae. aegypti were implemented on the basis of community participation. These measures included release of mosquito larvivorous fish in the drinking water storage facilities, application of larvicides to the water storage facilities in vegetable gardens, removal of discarded and unused containers and tires, improvement of household water storage facilities, and increase of potable water supply. Before implementation of the integrated control measures in 1988, 74% of the water-containing vessels were water storage facilities, and 24% of those were infested by Ae. aegypti. In 1989, the Breteau index for the entire island, indicating the average distribution density for larval Ae. aegypti, was 53.9, as compared to an index of 1.2 in 1996. In 4 villages located at the southwest and middle of the island, Ae. aegypti nearly became extinct because of the enthusiastic participation of the community. Before the implementation of integrated control, Ae. aegypti was the dominant species in containers both inside and outside the household, but after the integrated control, Aedes albopictus became predominant outside.
- Evolutionary Relationships of Endemic/Epidemic and Sylvatic Dengue Viruses
Wang, E; Ni, H; Xu, R; Barrett, ADT; Watowich, SJ; Gubler, DJ; Weaver, SC*
Journal of Virology [J. Virol.], vol. 74, no. 7, pp. 3227-3234, Apr 2000
Endemic/epidemic dengue viruses (DEN) that are transmitted among humans by the mosquito vectors Aedes aegypti and Aedes albopictus are hypothesized to have evolved from sylvatic DEN strains that are transmitted among nonhuman primates in West Africa and Malaysia by other Aedes mosquitoes. We tested this hypothesis with phylogenetic studies using envelope protein gene sequences of both endemic/epidemic and sylvatic strains. The basal position of sylvatic lineages of DEN-1, -2, and -4 suggested that the endemic/epidemic lineages of these three DEN serotypes evolved independently from sylvatic progenitors. Time estimates for evolution of the endemic/epidemic forms ranged from 100 to 1,500 years ago, and the evolution of endemic/epidemic forms represents relatively recent events in the history of DEN evolution. Analysis of envelope protein amino acid changes predicted to have accompanied endemic/epidemic emergence suggested a role for domain III in adaptation to new mosquito and/or human hosts.
- Stimulation of Dengue Virus Replication in Cultured Aedes albopictus (C6/36) Mosquito Cells by the Antifungal Imidazoles Ketoconazole and Miconazole
Lee, E; Mclean, K; Weir, RC; Dalgarno, L
Virology, vol. 269, no. 1, pp. 1-6, 30 Mar 2000
Replication of dengue type 3 virus in Aedes albopictus C6/36 cells was enhanced more than 50-fold by addition of the antifungal imidazole derivative ketoconazole within the first 4 h of infection. The stimulatory effect was reflected in the yield of infectious virus and in levels of viral RNA and protein synthesis. Enhanced yields were observed also for other flaviviruses, including dengue type 2 virus and Murray Valley encephalitis virus. Increased yields of dengue type 3 virus were not observed in African green monkey kidney (Vero) cells, human monocytic (U-937) cells, or cells of the mosquito Toxorhynchites amboinensis (TRA-171).
- Aedes albopictus from Albania: A potential vector of dengue viruses
Vazeille-Falcoz, M; Adhami, J; Mousson, L; Rodhain, F
Journal of the American Mosquito Control Association [J. Am. Mosq. Control Assoc.], vol. 15, no. 4, pp. 475-478, Dec 1999
Aedes albopictus collected in Durazzo, the main port of Albania, were tested for oral susceptibility to dengue type 2 virus and their infection rates were compared to those of an Aedes aegypti strain (Paea) and another strain of Ae. albopictus (Tananarive). Infection rates for the Albanian Ae. albopictus were dose dependent, ranging from 38.9 plus or minus 13.6% to 85.1% with the titer of the meal increasing from 10 super(8.1) to 10 super(9.1) 50% mosquito infectious doses (MID sub(50))/ml. The percentage of infected females was lower for the Ae. albopictus Durazzo strain than for the Ae. aegypti Paea strain: 38.9 plus or minus 13.6% compared with 92.4 plus or minus 4.9% for a meal of 10 super(8.1) MID sub(50)/ml, respectively. However, the difference was less when the titer of the meal was increased: 85.1% compared with 100% for a meal of 10 super(9.1) MID sub(50)/ml, respectively. The infection rate was also lower for the Durazzo strain than for the Tananarive strain of Ae. albopictus. The degree of viral replication in infected females was not significantly different in the 3 strains tested and we were able to demonstrate the ability of females from the Durazzo strain to transmit the virus in the course of a blood meal. Our results lead us to conclude that Ae. albopictus from Albania could serve as a vector for dengue virus.
- Use of a funnel trap for collecting immature Aedes aegypti and copepods from deep wells in Yogyakarta, Indonesia
Gionar, YR; Rusmiarto, S; Susapto, D; Bangs, MJ
Journal of the American Mosquito Control Association [J. Am. Mosq. Control Assoc.], vol. 15, no. 4, pp. 576-580, Dec 1999
During the course of a "dry" season dengue vector survey, indoor and outdoor household wells were sampled for the possible presence of immature mosquitoes and copepods. With a simple floating funnel trap, Aedes aegypti immature stages were captured in over 33% of the sampled wells (n = 93) during a 24-h trapping period per well. Average number of larvae (all instars) per positive well was 8.8 (range 1-63). Positive wells varied in depth from 2.7 to 14.7 m (8.8-48.2 ft), with a mean of 7.9 plus or minus SE 0.5 m in well rim to water surface. Only 4 wells (4.3%) contained Culex quinquefasciatus larvae. Only 1 of 31 infested wells contained both species. Aedes albopictus was not detected in any of the wells. Cyclopoid copepods were captured in 15% of the wells. No significant difference was found between positive and negative wells with regard to the physical characteristics (inside diameter, distance to water level) or the depth and volume of water held at the time of sampling. A significant association was found between wells positive for larvae and numbers of other positive containers in the vicinity of the wells. In general, wells containing copepods had fewer larvae present in the trap, possibly indicating some level of natural population regulation of Ae. aegypti occurring in the well; however, this association was not significant. Preliminary results indicate that wells in Yogyakarta serve as important permanent habitats for Ae. aegypti, especially during the dry season.
- Solid waste pollution and breeding potential of dengue vectors in an urban and industrial environment of Assam
Dutta, P; Khan, SA; Khan, AM; Sharma, CK; Doloi, PK; Mahanta, J
Journal of Environmental Biology [J. Environ. Biol.], vol. 20, no. 4, pp. 343-345, Oct 1999
Solid waste pollution and its potential as health hazard for vector borne diseases was investigated in Assam. A town and an oil industrial colony were randomly selected for the study. An entomological survey was conducted to evaluate the breeding potential of Aedes mosquitoes - the vectors of dengue in different container habitats originating from solid waste materials frequently dumped. Profuse breeding of dengue vectors viz. Aedes aegypti and Aedes albopictus has been detected in such solid waste materials which store rain water. The breeding of Aedes aegypti, the primary vector of dengue in India is more pronounced than Aedes albopictus. This study reveals that besides the air coolers in cities, the solid waste pollution is the major contributing factor in urban and industrial environments for the increase of the population density of the container breeding dengue mosquitoes, thereby causing annoyance as well as posing a severe threat of transmitting dengue virus.
- Mosquito Fauna in Water-Holding Containers with Emphasis on Dengue Vectors (Diptera: Culicidae) in Chungho, Taipei County, Taiwan
Teng, Hwa-Jen; Wu, Yen-Li; Lin, Ting-Hsiang
Journal of Medical Entomology [J. Med. Entomol.], vol. 36, no. 4, pp. 468-472, Jul 1999
A survey was conducted to characterize the mosquito fauna in water-holding containers in residential and open areas with emphasis on Aedes albopictus Skuse, and to determine the prevalence of mosquito-positive containers to obtain background information for a source reduction program. Seven container-inhabiting mosquito species were collected in residential areas, including Ae. albopictus, Culex quinquefasciatus Say, C. pallidothorax Theobald, C. neomimulus Lien, C. bicornutus Theobald, C. fuscanus Wiedemann, and Tripteroides aranoides Theobald. Ae. albopictus was the most abundant species and was collected in 18.49% of the containers examined. Other mosquito species were found in 0.02-0.16% of the total numbers of water containers checked. Of the positive water containers, 97.33% contained Ae. albopictus larvae. Sixteen species were collected in open areas away from residential sites. Ae. albopictus was most abundant and was present in 24.50% of the total number of containers examined. C. bicornutus, C. quinquefasciatus, and C. pallidothorax were present in 2.17, 1.48, and 1.08%, respectively. Ae. albopictus larvae were found in 74.78% of the mosquito-positive water containers. The mean Breteau index ( plus or minus SE) in 1997 (17.22 plus or minus 1.59 mosquito-positive containers per 100 premises) per village in residential areas was not significantly higher than the index in 1996 (16.86 plus or minus 1.33). The frequency of occurrence of Ae. albopictus in different containers is presented. A greater preference for containers in outdoor habitats was found. The ratio of the total number of containers indoors and outdoors per premises was 1.15:1.00, whereas the ratio of mosquito-positive containers indoors and outdoors was 1.00:1.83. Most indoor breeding containers (86.11%) in residential areas were used for planting purposes and for recreation (12.50%). The number of breeding containers in residential areas that were classified as trash increased from 0.35% indoor to 39.03% outdoor, whereas the number used for planting reduced to 34.95%. Most breeding containers (63.02%) in open areas were trash; natural containers (11.86%) were the 2nd most common breeding site followed by temporarily unused (8.84%), watering (6.98%), and planting containers (5.81%).
- Medically Important Mosquitoes of the World's Largest River Island, Majuli, Assam
Dutta, P; Khan, SA; Sharma, CK; Doloi, P; Mahanta, J
Entomon, vol. 24, no. 1, pp. 33-39, Mar 1999
Entomological studies were conducted in Majuli, the largest river island of the world during 1996. This is the maiden study and documentation of mosquito fauna of this unique ecosystem. Surveys were carried out during the months of April and October (pre and post monsoon seasons), 1996 to find out the mosquito species, particularly, the disease vectors prevalent in this island. This island is devoid of forests or hills. Bamboo and banana plantations are abundant along the sides of the roads and embankments. Entomological collections were made by collecting both immatures and adult mosquitoes. In immature surveys, a total of 18 species under 6 genera were collected from different habitat types. In adult collections, a total of 28 species under 5 genera were collected which includes the potential vectors of Japanese encephalitis (JE). None of the primary malaria vectors were detected and moreover, no indigenous malaria cases have been reported from this island. Only two clinically suspected cases of JE have been reported in 1996. Presence of the potential dengue vector, Aedes albopictus, and abundance in breeding habitats of these mosquitoes in the island is also noteworthy.
- Changing epidemiology of dengue hemorrhagic fever in Thailand
Chareonsook, O; Foy, HM; Teeraratkul, A; Silarug, N
Epidemiology and Infection [Epidemiol. Infect.], vol. 122, no. 1, pp. 161-166, Feb 1999
Dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) are reportable diseases, the third most common causes for hospitalization of children in Thailand. Data collected from the Ministry of Public Health were analysed for trends. Rates of DHF increased in Thailand until 1987 when the largest epidemic ever, 325/100000 population, was recorded. Whereas the disease used to be confined to large cities, the rate is now higher in rural (102.2 per 100000) than urban areas (95 times 4 per 100000 in 1997). The age of highest incidence has increased, and the age group most severely affected is now those 5-9 years old (679/100000 in 1997). The case fatality rate has decreased with improved treatment and is now only 0.28%.
- Isolation of Japanese Encephalitis Virus from Four Species of Aedes Mosquito in Yunnan Province
Zhang, Hailin; Shi, Huafang; Mi, Zhuqing; Zi, Dengyun; Gong, Zhengda
Virologica Sinica [Virol. Sin.], vol. 14, no. 1, pp. 32-35, 1999
A total of 19 367 adult female mosquitoes belonging to 16 species of Aedes genus were captured from nine countries, south-western part of Yunnan Province, China, and were examined by C6/36 cell method and suckling mouse method. Two strains of Japanese encephalitis (JE) virus were isolated from 6 491 (185 pools) Aedes albopictus, two strains of JE virus were isolated from 1605 (50 pools) Ae. vexans, two strains of JE virus were isolated from 772 (23 pools) Ae. lineatopennis, and a strain of JE virus was isolated from 103 (4 pools) Ae. assamensis. Isolation of JE virus was negative to other 12 species of Aedes mosquitoes. Ae. albopictus was the superior species of mosquitoes in bamboo forest. These results indicated that Ae. albopictus from Yunnan has a potential role in the maintenance and transmission of JE virus in nature. Ae. vexans, Ae. lineatopennis and Ae. assamensis are also considered to be transmitting vector of JE virus in Yunnan.