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The derivations of the names of 74 Anopheles species and one subgenus are explained together with accounts of the life and scientific work of people who have been honored by having a mosquito named after them. Descriptive accounts are given of geographical locations, whether towns, regions or counties, that have had anopheline species named after them.
Sugar feeding by male mosquitoes is critical for their success in mating competition. However, the facets of sugar source finding under natural conditions remain unknown. Here, evidence obtained in Western Burkina Faso indicated that the distribution of An. gambiae s.s. (M and S molecular forms) males across different peri-domestic habitats is dependent on the availability of potential sugar sources from which they obtain more favorable sites for feeding or resting. Among field-collected anophelines, a higher proportion of specimens containing fructose were found on flowering Mangifera indica (Anacardiaceae), Dolonix regia (Fabaceae), Thevetia neriifolia (Apocynaceae), Senna siamea, and Cassia sieberiana (both Fabaceae) compared to that recorded on other nearby plants, suggesting that some plants are favored for use as a sugar source over others. Y-tube olfactometer assays with newly-emerged An. gambiae s.s. exposed to odors from individual plants and some combinations thereof showed that males use odor cues to guide their preference. The number of sugar-positive males was variable in a no-choice cage assay, consistent with the olfactory response patterns towards corresponding odor stimuli. These experiments provide the first evidence both in field and laboratory conditions for previously unstudied interactions between males of An. gambiae and natural sugar sources.
Differences in biological features of immature and adult Aedes aegypti, as well as variability in vector competence, seem consistent with the existence of genetic variation among subpopulations and adaptation to local conditions. This work aims to compare the bionomics of four Ae. aegypti subpopulations derived from different geographical regions reared under temperate conditions. Life statistics of three Ae. aegypti subpopulations from the provinces of Córdoba, Salta, and Misiones were studied based on horizontal life tables. The Rockefeller strain was used as a control. The development time required to complete the larva and pupa stages varied from 6.91 to 7.95 and 1.87 to 2.41 days, respectively. Significant differences were found in mean larval development time between the Córdoba and Orán subpopulations. The larva-pupa development time was similar in all the subpopulations. However, survival values varied significantly between the Orán and San Javier subpopulations. The proportion of emergent males did not differ from females within each subpopulation nor among them. Adult longevity was similar among the subpopulations. The average number of eggs laid by each female was significantly different. The Rockefeller strain laid a significantly greater number of eggs (463.99 eggs/female) than the rest of the subpopulations. Moreover, differences in the demographic growth parameter Ro were detected among the four subpopulations. The differences obtained in larval development time, larva-pupa survival values, and net reproductive rates among the subpopulations might reflect underlying genetic differences as a result of colonization from different regions that probably involve adaptations to local conditions.
Laboratory colonization of hematophagous insects must include an efficient method of blood feeding, preferably by artificial means. Strict rules for obtaining animal use permits, extensive animal maintenance costs, and indirect anesthesia effects on animal health warrant the development of an artificial membrane feeding technique for sand fly colonization in laboratories. An attempt was made to colonize Lutzomyia shannoni using an artificial blood feeding membrane to replace the use of live animals commonly used for sand fly blood-feeding purposes. Lutzomyia shannoni readily fed through a pig intestine membrane exposed at an angle of 45°. However, it did not feed through a chicken skin membrane. Olfactory attractants were unable to improve blood-feeding efficiency. Plaster of Paris was the most suitable oviposition substrate. Female L. shannoni adults laid no eggs on moist sand substrate. Sand fly adults held in groups of ten or more laid higher numbers of eggs than did individually maintained sand flies. Inclusion of the L. longipalpis oviposition hormone dodecanoic acid or the presence of previously laid eggs did not stimulate L. shannoni oviposition. The average L. shannoni egg, larval, and pupal duration were 9.3, 36.7, and 17.8 days, respectively. The addition of a 20% sugar solution improved adult female longevity. Females survived longer (14.8 days) than males (11.9 days). Lutzomyia shannoni was successfully colonized in the laboratory for up to four generations using this artificial membrane technique.
Chagas disease remains a public health concern in Brazil and other Latin American countries, mainly due to the potential domiciliation of native triatomine species. We analyzed the genetic variability of Triatoma pseudomaculata in sylvatic and peridomestic ecotopes throughout three localities in the northeastern state of Bahia, Brazil. We studied polymorphisms generated by random amplified polymorphic DNA (RAPD) and isoenzyme electrophoresis analyses. Based on RAPD analysis, each specimen was assigned to one of three genetic clusters. Although all sylvatic specimens from one locality were grouped into the same cluster, sylvatic and peridomestic specimens from the other two localities were broadly distributed between the remaining two clusters, suggesting that geographic population structuring was not occurring. Furthermore, isoenzyme analysis suggested that distinct populations were in Hardy-Weinberg equilibrium. Low statistical values for Wright's Fst index also supported the absence of population structuring and suggested the occurrence of panmixia. We conclude that genetic flow occurs between sylvatic and peridomestic T. pseudomaculata populations, probably as a consequence of passive and active dispersion of the insects, associated with deforestation and anthropic transformations.
We evaluated the oviposition response of gravid Aedes albopictus (Skuse) to six organic infusions. Laboratory and field-placed oviposition cups baited with water oak (Quercus nigra L.), longleaf pine (Pinus palustris P. Mill), or St. Augustine grass (Stenotaphrum secundatum (Walt.) Kuntze), as well as binary infusion mixtures of each, were used. In addition, a triple-cage, dual port olfactometer was used to measure upwind response of gravid individuals to these infusions. We found that Ae. albopictus deposited more eggs in infusion-baited cups compared with water alone. Moreover, significantly more eggs were laid in the water oak and a water oak-pine mixture as compared with the St. Augustine grass infusion in laboratory bioassays. However, a negative upwind response was observed with longleaf pine infusion in the olfactometer. In field cages, significantly more eggs were deposited in infusion-baited cups as compared with water alone and a greater percentage of eggs were deposited in cups containing a water oak and the water oak-longleaf pine mixture as compared with cups containing single infusions or their mixtures.
To evaluate the risk of transmission of vector-borne diseases, regular updates of the geographic distribution of insect vectors are required. In the archipelago of Cape Verde, nine mosquito species have been reported. Of these, four are major vectors of diseases that have been present in the archipelago: yellow fever, lymphatic filariasis, malaria and, currently, an outbreak of dengue. In order to assess variation in mosquito biodiversity, we have carried out an update on the distribution of the mosquito species in Cape Verde, based on an enquiry of 26 unpublished technical reports (1983–2006) and on the results of an entomological survey carried out in 2007. Overall, there seems to be a general trend for an expansion of biological diversity in the islands. Mosquito species richness was negatively correlated with the distance of the islands from the mainland but not with the size of the islands. Human- and/or sporadic climatic-mediated events of dispersal may have contributed to a homogenization of species richness regardless of island size but other ecological factors may also have affected the mosquito biogeography in the archipelago. An additional species, Culex perexiguus, was collected for the first time in the archipelago during the 2007 survey.
Two western equine encephalomyelitis virus (WEEV) strains have been isolated in China. Our previous studies have verified that the mosquito Culex pipiens pallens Coquillett (Diptera: Culicidae) infected with WEEV was capable of transmitting this arbovirus, but it was not clear how the sequential multiplication and spread of virus occurred within the mosquito. In this study, we observed the distribution of WEEV antigen in orally-infected Cx. p. pallens by immunohistochemistry in order to better understand the initial infection, dissemination, and transmission of WEEV in the potential vector. Orally-infected WEEV dissemination varied within the different tissues of Cx. p. pallens, with virus antigen consistently observed in the salivary glands, foregut, midgut epithelial cells, Malpighian tubules, hindgut, and ovarian follicles of some individuals after various days of extrinsic incubation. We suggest that Cx. p. pallens, the potential vector of WEEV, has the ability to harbor the virus through the alimentary system, and the midgut epithelial cell may be the initial site of WEEV replication after ingestion of a viremic blood meal.
The role of lactic acid was evaluated for attraction of Culex nigripalpus, Culex quinquefasciatus, Culex tarsalis, and Aedes aegypti in the laboratory using a dual-port olfactometer. When lactic acid was combined with chicken odor, attraction was increased for Cx. quinquefasciatus compared to chicken odor alone but not for Cx. nigripalpus, Cx. tarsalis, and Ae. aegypti. Lactic acid combined with hand odor did not change attraction of Cx. tarsalis and Ae. aegypti but decreased attraction of Cx. nigripalpus and Cx. quinquefasciatus. The addition of lactic acid to CO2 increased attraction of Ae. aegypti and Cx. quinquefasciatus but reduced attraction of Cx. nigripalpus and Cx. tarsalis. Use of commercial lactic acid baits with CO2 resulted in a similar trend except for Cx. nigripalpus which showed no difference. A blend of lactic acid, acetone, and dimethyl disulfide was attractive to Ae. aegypti (63.4%) but elicited low responses by all Culex spp. (1.3–26.8%). Addition of the blend to CO2 increased attraction of Ae. aegypti and Cx. quinquefasciatus but reduced attraction of Cx. nigripalpus and Cx. tarsalis. The mixture of compounds plus CO2 was as attractive as a hand for Cx. quinquefasciatus, Cx. tarsalis, and Ae. aegypti.
Our objective was to study and evaluate the richness and diversity of Phlebotominae fauna in the Duas Bocas Biological Reserve (DBBR) in the state of Espírito Santo, in southeastern Brazil. Sand fly collections were carried out during four consecutive nights each month between August 2007 and July 2008 at DBBR by using CDC automatic light traps and an illuminated Shannon trap. Specific richness (S) and Shannon diversity index (H) was calculated for each trap. We collected 18,868 sand flies belonging to 29 species and 13 genera. Nyssomyia yuilli yuilli was the most abundant species followed by Psychodopygus ayrozai, Ps. hirsutus, Psathyromyia pascalei, and Ps. matosi. We recorded Brumptomyia cardosoi, Br. troglodytes, and Ps. geniculatus for the first time in the state of Espírito Santo. We discuss the differences in diversity and richness of the sand flies in both traps and in relation to other Brazilian localities and biomes. We also discuss the possibility of wild transmission of Leishmania in the DBBR and the influence of the sand fly species in leishmaniasis transmission to the adjacent areas of the reserve.
We analyzed the feeding preference of Cnesterodon decemmaculatus, a small-bodied poecilid native from the Rio de la Plata and proximate Atlantic Basins in South America. This species has a wide distribution in Uruguayan water bodies but its effectiveness as a predator of mosquito larvae has not been tested. In laboratory trials, five aquatic invertebrates were offered simultaneously as potential prey to fish: Daphnia pulex (Cladocera), copepods, two different instars of mosquito larvae (Culex pipiens), and the 4th instar of Chironomidae larvae. Preference was measured by the Chesson's electivity index (α). In order to determine differences in prey preference according to fish size, individuals ranging from 9.5 mm to 35.3 mm were classified in three different body size classes: small, medium, and large. Small fish showed preference for copepods, while medium-sized fish preferred the smallest mosquito larvae instars and Chironomidae larvae. We conclude that C. decemmaculatus is a Zooplankton facultative-feeder fish that prefers large-bodied Zooplankton but is a weak predator of mosquito larvae. Thus, the introduction of C. decemmaculatus as a biological-control agent in natural environments is not an effective strategy.
The black salt marsh mosquito, Aedes taeniorhynchus, is a serious nuisance pest and a potential vector of a number of arboviruses. This study examined the effect of wind direction, wind speed, temperature, and time of year on the abundance of Ae. taeniorhynchus collected in CO2-baited light traps at 12 sites in the Florida Keys during 2004. The dependent variable analyzed was the natural log of weekly mosquito abundance. The previous week's wind speed and wind direction, and the current week's temperature were used as independent variables. Simple and multiple linear regression models were used to assess the significance and nature of association between the meteorological variables and the natural log of mosquito abundance, and to determine whether the meteorological variables had significant associations with mosquito abundance after also controlling for time of year. Week of year was treated as a circular independent variable in the regression models, using the sine and cosine of week in radians to model the periodic seasonal fluctuation in mosquito abundance. Mosquito abundance was significantly associated with all meteorological variables and with week of year. Individually, previous week's wind speed and wind direction, and current week's temperature were able to explain respectively 24.5%, 24.5%, and 52.1% of the variation in mosquito abundance observed over the year. Week of year had the strongest individual association with mosquito abundance, explaining 65.7% of the variation in mosquito abundance. The meteorological variables were still significantly associated with mosquito abundance, after controlling for week of year. Week and the meteorological variables together explained 79.2% of the variation in mosquito abundance. The regression models fit to the data from this study suggest a strong periodic seasonal variation in mosquito abundance, with meteorological conditions explaining a significant portion of the variation beyond the seasonal trend.
The occurrence and abundance of mosquito populations maybe associated with the abundance of predators. We examined the relationship between aquatic predators and populations of mosquitoes in animal water troughs in Waikanae, New Zealand. We also investigated the effects of water volume and environmental factors (temperature, rainfall, wind speed, humidity, and pressure) in order to further understand factors influencing mosquito and predator populations. Logistic regression indicated that the presence or absence of mosquitoes was primarily affected by three factors: predator abundance, week of observation, and water volume. Pearson's correlation indicated that the presence of predators had a positive correlation with water volume (r2= 0.176, p< 0.05). Otherwise, the presence of mosquito larvae in water troughs was negatively correlated with water volume (r2=-0.159, p=0.022) and wind speed (r2=0.142, p=0.041). We established a translocation experiment in which predators or mosquitoes were moved between troughs in order to examine the prey survival rate after exposure to Anisops wakefieldi predators. The survival rate of mosquitoes was not significantly different, between 0–0.1%, irrespective of the number of predators translocated (1–9) or the initial mosquito density (20–70 larvae). Our results suggested that A. wakefieldi predators may have the potential to be a promising biological control tool for the control of mosquito populations by altering mosquito population dynamics.
Culex quinquefasciatus plays a major role in the transmission of important parasites and viruses throughout the world. Because temperature is an important limiting factor on growth and longevity of all mosquito species, estimating the reaction norms provides very important basic information for understanding both plasticity and individual variations of the population. In the present study, Cx. quinquefasciatus were maintained at five different constant temperatures (15°, 20°, 23°, 27°, and 30°C) for two subsequent generations. Reproductive population parameters in blood-fed mated females and longevities of virgin and blood-fed mated adults reared at different temperatures were compared for the two generations. Longevity increased as temperature decreased within a range of 15° to 30°C for the unmated adults, and 15° to 27°C for the mated and blood-fed adults. Generation times were as long as 124.07 and 106.76 days for two subsequent generations reared at 15°C, and the highest intrinsic rate of increase (rm) values were estimated at 0.22 and 0.18, respectively, from the cohorts reared at 27°C. For survival rates, reproductive rates (R0), and rm values, 30°C was found to be a critical temperature for this species. These cohorts produced the smallest amount of eggs (R0= 5.06), rm values decreasing across generations (from 0.11 to 0.06), and the survival rates from egg to adult were found to be insufficient (16.1 and 10.8%). Additionally, the rate of exponential increase with age and age specific mortalities (b) were calculated for the virgin cohorts. Age specific mortality rates increased as temperature decreased. The increase in mortality rates started to accelerate at 27°C and was more pronounced at 30°C, for both females and males. We estimated the coefficients of variation for the b values in which females have smaller coefficients than those of the males at all temperatures.
Elucidating feeding relationships between hosts and parasites remains a significant challenge in studies of the ecology of infectious diseases, especially those involving small or cryptic vectors. Black-tailed prairie dogs (Cynomys ludovicianus) are a species of conservation importance in the North American Great Plains whose populations are extirpated by plague, a flea-vectored, bacterial disease. Using polymerase chain reaction (PCR) assays, we determined that fleas (Oropsylla hirsuta) associated with prairie dogs feed upon northern grasshopper mice (Onychomys leucogaster), a rodent that has been implicated in the transmission and maintenance of plague in prairie-dog colonies. Our results definitively show that grasshopper mice not only share fleas with prairie dogs during plague epizootics, but also provide them with blood meals, offering a mechanism by which the pathogen, Yersinia pestis, may be transmitted between host species and maintained between epizootics. The lack of identifiable host DNA in a significant fraction of engorged Oropsylla hirsuta collected from animals (47%) and prairie-dog burrows (100%) suggests a rapid rate of digestion and feeding that may facilitate disease transmission during epizootics but also complicate efforts to detect feeding on alternative hosts. Combined with other analytical approaches, e.g., stable isotope analysis, molecular genetic techniques can provide novel insights into host-parasite feeding relationships and improve our understanding of the role of alternative hosts in the transmission and maintenance of disease.
The mosquito larvicide methoprene is a juvenile growth hormone mimic that is widely used to control mosquito larvae in stormwater catch basins. This study addresses two concerns pertaining to methoprene's use for mosquito control. First, measurements of methoprene concentrations were made from water in catch basins that had been treated with methoprene and from an adjoining salt pond near where the treated catch basins emptied. The concentrations of methoprene in catch basins and at drainage outlets after application at the rates currently used for mosquito control in southern Rhode Island were 0.5 ppb and lower, orders of magnitude below what has been determined as detrimental to organisms other than mosquitoes. Second, the effects of methoprene on the communities that live in catch basins were evaluated both in simulated catch basins in the laboratory and in actual catch basins in the field. We found no evidence of declines in abundances of any taxa attributable to the application. Furthermore, we found no consistent changes in community-level parameters (e.g., taxonomic richness, and dominance-diversity relationships) related to methoprene application in either field or laboratory trials.
We assessed some ecological parameters of Triatoma brasiliensis in rock piles in the state of Ceará during the rainy and dry seasons. The greatest density was in April (median = 12.5 triatomines/site). The greatest abundance was in December, when the insects were more dispersed and the density per site was lower (6 triatomines/site). The nutritional status of females and 5th instar nymphs was increased in July. The rate of T. cruzi infection reached its highest peak in July (10.9%). ELISA revealed that the principal food sources were birds (33.1%), followed by armadillos (18.8%). Food sources were more frequently identified during the rainy season. T. brasiliensis specimens collected in the drought tended to: i) present lower rates of T. cruzi infection and gut content reactivity to tested antisera, ii) have a poorer nutritional status, iii) exhibit lower fecundity, iv) be more dispersed among the studied collection sites, and v) be more abundant and easily collected in the surface of the rocks, possibly reflecting an increased searching for blood meals. Such findings underscore epidemiological concerns and allow inferences about the season when triatomines can more frequently invade the peridomestic environment in search of food and recolonize artificial structures.
The double sticky trap (DST) is described for the first time and is evaluated along with standard ovitraps and sticky traps (STs) to determine population densities of Ae. aegypti in the urban township of St. Augustine and the rural community of Tamana, Trinidad, West Indies. Ten houses were selected at each study site. At each of the ten houses, one ovitrap, one ST, and one DST were placed using the criteria established for placement of ovitraps. The results showed the three trapping methods successfully collected Ae. aegypti mosquitoes. All three traps collected significantly more adults or eggs in St. Augustine than in Tamana. DSTs collected 2,286 adults from St. Augustine vs 316 adults from Tamana (p<0.002), STs collected 1,480 and 220 adults, respectively (p<0.01), and the ovitraps collected 2,735 and 517 eggs, respectively from St. Augustine and Tamana (p<0.002). Based on these results, the DSTs collected significantly (P<0.02) more adults than the STs. The DSTs and STs collected both adult and immature stages which can be used for toxicology, virology, and PCR studies and are suitable alternative Ae. aegypti surveillance tools for the Caribbean and Latin American region.
An understanding of urban aquatic environments as mosquito larval habitats is necessary to prioritize sites for surveillance and control of arbovirus vectors in urban areas. Natural and artificial water bodies at ground level that may be larval mosquito habitats in Córdoba city, Argentina were surveyed. Data on the characteristics of aquatic sites and the presence and abundance of mosquito larvae and pupae were collected in the summer of 2006, coinciding with the first report of human WNV and following an outbreak of St. Louis encephalitis in 2005. Eight species in the genera Aedes, Culex, and Mansonia were identified. At 64.2% (34 of 53) of the sites, only one species was collected, while 3.8% (2 of 53) had three associated species, the highest richness found per site. Culex quinquefasciatus represented over 99% (out of 32,729) of the specimens. It was also the most widely distributed and detected under diverse habitat conditions. Although puddles and semi-permanent pools harbored a greater number of species, drainages and channels may be more relevant as risk factors from an epidemiological point of view because they showed the highest larval densities, mainly of Cx. quinquefasciatus (vector of SLE and WNV). Also, higher densities of this species were associated with stormwater runoff and sewage water, thus water management systems should be targeted and closely monitored for mosquito control purposes.
Blood intake causes significant changes in ticks, triggering vital physiological processes including differential gene expression. A gene encoding Ixodes ricinus ML-domain containing protein (IrML) is one of the set of the genes that are strongly induced by blood meals. IrML belongs to the ML protein family that commonly occurs in diverse organisms and is involved in lipid binding and transport, pathogen recognition or in immune response. An IrML gene was amplified from cDNA of engorged I. ricinus females using the gene-specific primers designed on a basis of partial sequences of related genes for ML domain protein. IrML was shown to be expressed mainly in the gut, but also in salivary glands and hemolymph of all tick developmental stages. Using in situ hybridization, IrML transcripts were detected in type II and III salivary glands acini. Analysis of the predicted structure of I. ricinus ML-domain containing protein and its localization in the tick body could suggest that IrML is a secreted protein and is possibly involved in tick innate immunity.
Abundances of mosquito larvae and associated invertebrate communities were assessed in 27 temporary ponds during the spring season in wetland areas of Germany. Four genera of mosquitoes were identified: Aedes, Anopheles, Culex, and Culiseta. We focused our analyses on Aedes spp. because this genus was the most abundant (92% of total abundance) and frequently encountered mosquito (present in 65% of investigated sites). The abundance of Aedes spp. was negatively associated with the abundance of competitors for food, and to a lesser extent with those of intraguild predators and strict predators. The influence of these natural antagonists on larvae of Aedes was stronger in ponds with higher levels of dissolved oxygen (53 ± 4%) than in ponds with lower levels (16 ± 1%). The overall abundance of antagonists explained 42% of the variation in abundance of Aedes spp. at sites with higher levels of dissolved oxygen. Of this explained variation, competitors accounted for 34.7%, whereas the abundance of intraguild predators and strict predators accounted for only 6.8 and 0.5%, respectively. Therefore, the promotion of competing species might be an appropriate ecological approach for the control of Aedes spp. in temporary ponds in these areas.
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