Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact helpdesk@bioone.org with any questions.
The taxonomic status of the sand fly Phlebotomus (Euphlebotomus) argentipesAnnandale & Brunette 1908, which transmits Leishmania (Leishmania) donovani (Laveran & Mesnil 1903) in southern Asia, is reassessed, because variation in morphology, behavior, and distribution suggests it to be a complex of sibling species. The putative complex is composed of the nominotypical member Phlebotomus argentipes sensu stricto, Phlebotomus annandalei Sinton 1923 status revived and Phlebotomus glaucusMitra & Roy 1953 new status. An allolectotype is designated for the female of P. argentipes as well as neotypes for the males of P. annandalei and P. glaucus. Morphological descriptions, illustrations, and keys are presented to allow identification of adult males and females. Based on female morphological characters, P. argentipes s.s., P. annandalei and P. glaucus can be distinguished from each other using principal component analysis. P. glaucus is widespread in India, occurring sympatrically with P. argentipes s.s. in L. donovani-endemic foci, whereas P. annandeli is peripatric to the type species in Chennai, southern India. “In copula” is a process of postcopulatory sexual selection occurring as correlated coevolution of male and female reproductive traits, which drives species isolation. This pattern has been implicated in reproductive isolation among the members of the P. argentipes complex. Further research on adult behavior and larval biology of the P. argentipes complex is needed to understand the epidemiology and control of visceral leishmaniasis.
Lutzomyia França is the largest and most diverse sand fly genus in the New World and contains all the species involved in the transmission of American visceral leishmaniasis (AVL). Morphological characters were used to test the monophyly and to infer phylogenetic relationships among members of the Lutzomyia subgenus. Fifty-two morphological characters from male and female adult specimens belonging to 18 species of Lu. (Lutzomyia) were scored and analyzed. The resulting phylogeny confirms the monophyly of this subgenus and reveals four main internal clades. These four clades, however, do not support the classification of the subgenus in two series, longipalpis and cavernicola, because neither is necessarily monophyletic. Knowledge on phylogenetic relationships among these relevant vectors of AVL should be used as a tool for monitoring target taxa and a first step for establishing an early warning system for disease control.
During nine consecutive nights in July 2007 (from 18:15–05:45 h), mosquitoes landing-biting on humans were collected outdoors and indoors at the Turkey-Armenia border. A total of 1,005 females were collected consisting of nine species. The dominant species was Aedes dorsalis (Meigen) (47.5% of total catch), followed by Anopheles hyrcanus (Pallas) (22.9%), Culex theileri (Theobald) (9.3%), Ae. vexans (Meigen) (6.6%), Ae. caspius (Pallas) (4.9%), Anopheles maculipennis s.l. (Meigen) (3.1%), Culex territans (Walker) (2.8%), Coquillettidia richiardii (Ficalbi) (1.6%), and Cx. pipiens L. (1.5%). The biting rate outdoors (15.1 mosquitoes/human/h) was greater than indoors (3.4 mosquitoes/human/h). The landing-biting of Ae. dorsalis peaked at dusk (19:15–19:45 h) and dawn (04:15–04:45 h). Ae. vexons activity increased soon after dark (20:15–20:45 h) and reached a peak at dawn (04:15–04:45 h). Maximum biting activity of An. hyrcanus and Cx. theileri occurred during the first sampling interval after dusk (20:15–20:45 h). A large number of An. maculipennis s.l. adults were collected during the second half of the night. We believe that these findings will contribute to decisions on the timing of mosquito control in Ararat Valley.
Anopheles gambiae is the predominant malaria vector species in Ghana, western Africa, with a strong local presence of Anopheles melas Theobald along the southern coast. We studied the biting behavior of these two species of the Anopheles gambiae complex inland and at the coast in Ghana, with special attention to the local peoples' preference for outdoor sleeping. We collected mosquitoes at two sites in 2007, representing the moist semideciduous forest zone and the strand and mangrove zone, and the sampling was repeated in the dry and rainy seasons. Sampled mosquitoes were examined for species, parity and size (wing length), and we identified the hosts of their bloodmeals. We interviewed 288 of the village people to determine where and when they slept outdoors. Our study confirmed that An. gambiae is the only species of the An. gambiae complex in the Ashanti region and revealed that An. melas is highly dominant on the western coast of Ghana. Both species showed high human blood rates in indoor resting mosquito samples. More people sleep outside on the coast than inland. An. melas demonstrated high exophily. An. gambiae bit people more frequently indoors and did so more often during the dry season than in the rainy season. We suggest that the degree of exophily in An. melas may be affected by humidity and the availability of human as well as by the mosquitoes' innate habits.
Seventeen mosquito species were collected at eight cattle facilities in southern Alberta, Canada, during 2002–2004. Five species, Culiseta inornata (Williston), Aedes dorsalis (Meigen), Culex tarsalis (Coquillett), Aedes vexans (Meigen), and Aedes campestris Dyar & Knab accounted for 93.6% of the mosquitoes collected. Culiseta inornata, Ae. dorsalis, and Ae. campestris were trapped earliest in the year. Cs. inornata was active latest in the year and had the longest period of activity. Ae. dorsalis finished activity in late September and had the second longest period of activity. Ae. campestris was the first to complete its activity, resulting in a moderate period of activity. Cu. tarsalis and Ae. vexans appeared later in the season, disappeared by late September, and had the briefest periods of activity. Logistic regression was used to estimate relationships between the proportions of traps positive and mean weekly abundance for each species. Fifty percent of the traps were positive when abundance averaged 0.19–0.30 females per trap night. Logistic regression was used to determine the timing of the onset of activity and temperature thresholds for flight. Relationships between the proportion of positive traps and mean weekly temperature indicated that Cs. inornata had the lowest temperature threshold, Cx. tarsalis the greatest, and the remaining species had intermediate thresholds. Logistic regression indicated that mosquito presence was primarily affected by temperature and accumulated degree-days, with only Ae. vexans exhibiting a positive response to precipitation. The models can be used to predict the onset of activity as defined by when populations exceed a particular threshold.
Ochlerotatus japonicus japonicus (Theobald) is an invasive mosquito native to Japan, Korea, and eastern China. The species was first detected in the northeastern United States in 1998 and has rapidly spread throughout much of eastern North America. In addition to used tire casings, Oc. j. japonicus develops in a wide variety of artificial and natural container habitats, especially rock pools along stream beds. In an effort to evaluate the invasion success and impact of Oc. j. japonicus on populations of native container dwelling species, waste tire disposal sites and natural rock pool habitats were sampled for mosquito larvae throughout Connecticut in 2005, and data were compared with results from prior surveys made in 1987 and 1999. Oc. j. japonicus was the predominant species collected at the waste tire disposal sites regardless of surrounding landscape features, accounting for 55.9% of all larvae. A comparison with collections from prior surveys revealed a 90% reduction in the relative abundance of larval populations of Oc. triseriatus (Say) and significant reductions among larval populations of Oc. atropalpus (Coquillett) and Culex restuans Theobald. Oc. j. japonicus was also the most abundant mosquito collected in rock pool habitats, accounting for nearly 80% of all collected larvae, except where water temperatures exceeded 30°C. This was concomitant with significant declines in the relative abundance of Oc. atropalpus and Cx. restuans. We conclude that Oc. j. japonicus is a potentially effective competitor in rock pool and tire environments and may be responsible for reducing populations of several native species occupying these habitats through interspecific competition for limited resources. The exclusion of Oc. j. japonicus from warm water pools further suggests that a temperature barrier may exist for Oc. j. japonicus and that populations may not be able to colonize southern regions of the United States with relatively high summer temperatures.
Discarded vehicle tires are a common habitat for container mosquito larvae, although the environmental factors that may control their presence or abundance within a tire are largely unknown. We sampled discarded vehicle tires in six sites located within four counties of central Illinois during the spring and summer of 2006 to determine associations between a suite of environmental factors and community composition of container mosquitoes. Our goal was to find patterns of association between environmental factors and abundances of early and late instars. We hypothesized that environmental factors correlated with early instars would be indicative of oviposition cues, whereas environmental factors correlated with late instars would be those important for larval survival. We collected 13 species of mosquitoes, with six species (Culex restuans, Cx. pipiens, Aedes albopictus, Cx. salinarius, Ae. atropalpus, and Ae. triseriatus) accounting for ≈95% of all larvae. There were similar associations between congenerics and environmental factors, with Aedes associated with detritus type (fine detritus, leaves, seeds) and Culex associated with factors related to the surrounding habitat (human population density, canopy cover, tire size) or microorganisms (bacteria, protozoans). Although there was some consistency in factors that were important for early and late instar abundance, there were few significant associations between early and late instars for individual species. Lack of correspondence between factors that explain variation in early versus late instars, most notable for Culex, suggests a difference between environmental determinants of oviposition and survival within tires. Environmental factors associated with discarded tires are important for accurate predictions of mosquito occurrence at the generic level.
VECTOR CONTROL, PEST MANAGEMENT, RESISTANCE, REPELLENTS
This study evaluated the use of an insecticide-treated fruit juice bait against adult Culex pipiens s.l. L. from sewage ponds in Israel. The attractive toxic sugar bait (ATSB) solution (fruit juice, sugar, food dye, oral insecticide spinosad, and BaitStab, a mixture of slow-release substances and preservatives) was sprayed onto 10–15% of the surrounding vegetation of these ponds. The same bait solution, without insecticide, was sprayed onto vegetation at a similar site as a control. Mosquito abundance was monitored in treatment and control sites with six CDC light traps. Mosquitoes in the experimental sites decreased from ≈125 to approximately eight per trap. Mosquito abundance in the control sites was fairly stable and averaged ≈60 per trap during the study. Before starting the study parity of mosquitoes from the experimental and control sites averaged ≈20% muciparous females. After bait/insecticide application, only ≈3% of the females were multiparous in the treatment area.
Belowground stormwater treatment devices referred to as Best Management Practices (BMPs) can be persistent sources of Culex quinquefasciatus Say (Diptera: Culicidae) mosquitoes and in urban environments necessitate routine monitoring and insecticide treatment for control. The design of certain structural features of BMPs may discourage mosquito entry and oviposition, potentially reducing the need for control measures. From August 2007 to November 2008,29 BMPs were intermittently monitored for the presence of mosquitoes and compared against selected structural features. A bucket ovitrap was developed to estimate entry of oviposition-site-seeking females into BMPs via egg raft counts. The number of egg rafts collected was positively associated with larger diameters and shorter lengths of conveyance pipe from the nearest inlet or outlet and with increasing number of pickholes in BMP manhole covers. In contrast, the number of days pickholes were sealed against adult mosquito entry was negatively associated with eggs rafts. Findings suggest that the design of belowground BMPs and their conveyance systems can influence mosquito oviposition inside these structures. Specific design criteria with the greatest potential to minimize mosquito production and provide safe access for monitoring and control activities are discussed.
Preimmunization of mice with salivary gland homogenate (SGH) of long-term colonized (F29) female Phlebotomus papatasi Scopoli (Diptera: Psychodidae) induced protection against Leishmania major Yakimoff & Schokhor (Kinetoplastida: Trypanosomatidae) co-inoculated with the same type of SGH. In contrast, preimmunization of mice with SGH of wild-caught female P. papatasi did not confer protection against L. major co-inoculated with the same type of SGH. Similarly, SGH from recently colonized (F1) female P. papatasi did not protect mice against L. major. These results suggest that when developing a sand fly saliva-based vaccine, the natural vector populations should be considered.
Chagas disease is a serious public health problem in Ecuador, where nearly 230,000 individuals show Trypanosoma cruzi infection. Sylvatic T. cruzi transmission is a threat to current control strategies. This is because of the possibility of house reinfestation by sylvatic triatomines after insecticide treatment. This work quantified the spatial distribution of triatomines in sylvatic habitats and its relationship with nearby human dwellings. A simple random sampling design using live-baited traps and manual searches for triatomines was used in areas near human communities in Manabí province, Ecuador, during June and July 2007. We identified risk factors associated with triatomine density using generalized linear models, and developed predictive maps for triatomine density interpolation. There were 345 triatomines belonging to the species Rhodnius ecuadoriensis and Panstrongylus howardi collected in sylvatic areas. Spatial analyses revealed an aggregated distribution pattern of the sylvatic triatomine populations (clustered mostly at a distance smaller than 100 m). Generalized linear models showed that the distance from the nearest house, nest type, and height from ground level were the main factors explaining triatomine densities. Squirrel nests (Sciurus stramineus), located in plants other than palms, above 5 m and close to the domicile presented higher infestation. Interpolation maps of triatomine microdistribution are presented as potential tools to predict triatomine occurrence. The presence of sylvatic populations and the synanthropic tendency of the vectors highlight the need for continuous active and passive entomological surveillance for the long-term control of Chagas disease.
Chris D. Crowder, Megan A. Rounds, Curtis A. Phillipson, John M. Picuri, Heather E. Matthews, Justina Halverson, Steven E. Schutzer, David J. Ecker, Mark W. Eshoo
Ticks harbor numerous bacterial, protozoal, and viral pathogens that can cause serious infections in humans and domestic animals. Active surveillance of the tick vector can provide insight into the frequency and distribution of important pathogens in the environment. Nucleic-acid based detection of tick-borne bacterial, protozoan, and viral pathogens requires the extraction of both DNA and RNA (total nucleic acids) from ticks. Traditional methods for nucleic acid extraction are limited to extraction of either DNA or the RNA from a sample. Here we present a simple bead-beating based protocol for extraction of DNA and RNA from a single tick and show detection of Borrelia burgdorferi and Powassan virus from individual, infected Ixodes scapularis ticks. We determined expected yields for total nucleic acids by this protocol for a variety of adult tick species. The method is applicable to a variety of arthropod vectors, including fleas and mosquitoes, and was partially automated on a liquid handling robot.
Adult males of Mus musculus each infested with four first-instar (L1) larvae of Dermatobia hominis (Linneaus, Jr.) were used as donors of larvae to other mice (recipients). Larvae at four (L1), six (early L2), 12 (L2), or 20 (L3) days postinfestation (dpi), were implanted into the skin of each recipient. Only two of 38 mice (5.3%) were refractory to implants and three died after implantation. Developmental times (pre- plus postimplantation) of implanted larvae were of similar duration to those in larvae that completed their development in the original mice. The L3 that emerged from implanted hosts developed to pupae and fertile adult specimens, whose L1 descendants were used to maintain the D. hominis life cycle in our laboratory. The model described here has several potential applications, including studies of the host relationship with specific instars and the development of management and control measures to combat this Neotropical myiasis.
The purpose of this study was to describe the geographic distribution and model the ecological niche for Borrelia burgdorferi (Johnson, Schmidt, Hyde, Steigerwaldt & Brenner), Ixodes pacificus (Cooley & Kohls), and Ixodes angustus (Neumann), the bacterium and primary tick vectors for Lyme disease, in British Columbia (BC), Canada. We employed a landscape epidemiology approach using geographic information systems mapping and ecological niche modeling (Genetic Algorithm for Rule-set Prediction) to identify geographical areas of disease transmission risk. Forecasted optimal ecological niche areas for B. burgdorferi are focused along the coast of Vancouver Island, the southwestern coast of the BC mainland, and in valley systems of interior BC roughly along and below the N51° line of latitude. These findings have been used to increase public and physician awareness of Lyme disease risk, and prioritize future field sampling for ticks in BC.
An enclosure trapping experiment compared numbers and engorgement of Culicoides spp. taken from treated sheep (7.5% deltamethrin) to Culicoides from untreated sheep. Attack rates were low (0.2/ min), but 58% of Culicoides obsoletus s.l. and 67% of Culicoides parroti Kieffer engorged on untreated sheep, and no engorgement occurred on treated sheep on 0 and 4 d posttreatment. A UV light trap in a livestock barn collected eight Culicoides spp. (510 individuals), dominated by C. obsoletus (Meigen) (68%), Culicoides imicola Kieffer (19%), Culicoides circumscriptus Kieffer (8%), and Culicoides alazanicus Dzhafarov (4%). A more powerful but nonattractive fan trap collected five species (121 individuals) dominated by C. obsoletus (48%), C. imicola (36%), C. alazanicus (8%), and C. circumscriptus (7%). Parity of C. obsoletus and C. imicola did not vary between the light and fan traps. Engorged Culicoides in the barn (33 C. obsoletus and three C. imicola) had fed on sheep or goats (precipitin test).
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere