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1.
J Med Entomol. 2014 Sep;51(5):1043-50.

Factors associated with peridomestic Triatoma sanguisuga (Hemiptera: Reduviidae) presence in southeastern Louisiana.

Abstract

Although rare, there have been isolated reports of autochthonous transmission of Trypanosoma cruzi Chagas in the United States. In June 2006, a human case of domestically transmitted T. cruzi was identified in southern Louisiana. To examine the localized risk of human T. cruzi infection in the area surrounding the initial human case, environmental surveys of households in the area and a serological survey of the residents were performed between September 2008 and November 2009. Human T. cruzi infection was determined using a rapid antigen field test, followed by confirmatory enzyme-linked immunosorbent assay testing in the laboratory. A perimeter search of each participating residence for Triatoma sanguisuga (LeConte), the predominant local triatomine species, was also performed. No participating individuals were positive for antibodies against T. cruzi; however, high levels of T. cruzi infection (62.4%) were detected in collected T. sanguisuga. Households with T. sanguisuga presence were less likely to use air conditioning, and more likely to have either chickens or cats on the property. While the human risk for T cruzi infection in southeastern Louisiana is low, a high prevalence of infected T. sanguisuga does indicate a substantial latent risk for T. cruzi peridomestic transmission. Further examination of the behavior and ecology of T. sanguisuga in the region will assist in refining local T. cruzi risk associations.

PMID:
25276935
[PubMed - indexed for MEDLINE]
2.
Birth Defects Res A Clin Mol Teratol. 2014 Oct;100(10):792-6. doi: 10.1002/bdra.23297. Epub 2014 Sep 5.

Developmental outcomes in young children born to mothers with west nile illness during pregnancy.

Author information

  • 1Tulane University, New Orleans, Louisiana.

Abstract

BACKGROUND:

West Nile virus (WNV) infection is associated with acute morbidity and mortality in adults and children. Information on the effects of maternal WNV illness during pregnancy on early childhood development is limited. This study was designed to examine the relationship between maternal WNV illness during pregnancy and birth and developmental outcomes at age 3 years.

METHODS:

Mother-child participants were identified using a national surveillance registry for women with WNV illness during pregnancy. Maternal and infant health data and relevant family characteristics were obtained through medical record reviews and maternal questionnaires. All infants received ophthalmologic examinations. Child development was evaluated at age 3 years using the Bayley Scales of Infant and Toddler Development-Third Edition (Bayley-III).

RESULTS:

As a group, the children's (N = 11) birth weight, head circumference, and infant ophthalmologic examination results were within age expectations; one child was born preterm (gestational age 36 weeks). Mean (SD) age at the time of Bayley-III testing was 36.7 (3.8) months. The group's mean performance on the Bayley-III was at or above age level in all domains, but one child showed a mild delay in the Adaptive domain. The variability observed in this sample (1/53 [1.9%] Domain scores < -2.0 SDs) was consistent with expectations based upon the distribution of Bayley-III Domain scores in the general population.

CONCLUSION:

Maternal WNV infection does not appear to be associated with global developmental delays in young children. These results are preliminary, however, and require confirmation in future research. Birth Defects Research (Part A) 100:792-796, 2014. © 2014 Wiley Periodicals, Inc.

© 2014 Wiley Periodicals, Inc.

KEYWORDS:

West Nile virus; early childhood development; infancy; pregnancy

PMID:
25196266
[PubMed - in process]
Icon for John Wiley & Sons, Inc.
3.
PLoS One. 2013 Dec 2;8(12):e81211. doi: 10.1371/journal.pone.0081211. eCollection 2013.

Use of anti-Aedes aegypti salivary extract antibody concentration to correlate risk of vector exposure and dengue transmission risk in Colombia.

Author information

  • 1Louisiana State University, Baton Rouge, Louisiana, United States of America ; Universidad de Pamplona, Pamplona, Colombia.

Abstract

Norte de Santander is a region in Colombia with a high incidence of dengue virus (DENV). In this study, we examined the serum concentration of anti-Aedes salivary gland extract (SGE) antibodies as a biomarker of DENV infection and transmission, and assessed the duration of anti-SGE antibody concentration after exposure to the vector ceased. We also determined whether SGE antibody concentration could differentiate between positive and negative DENV infected individuals and whether there are differences in exposure for each DENV serotype. We observed a significant decrease in the concentration of IgG antibodies at least 40 days after returning to an "Ae. aegypti-free" area. In addition, we found significantly higher anti-SGE IgG concentrations in DENV positive patients with some difference in exposure to mosquito bites among DENV serotypes. We conclude that the concentration of IgG antibodies against SGE is an accurate indicator of risk of dengue virus transmission and disease presence.

PMID:
24312537
[PubMed - indexed for MEDLINE]
PMCID:
PMC3846924
Free PMC Article
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4.
Am J Trop Med Hyg. 2013 May;88(5):986-96. doi: 10.4269/ajtmh.12-0109. Epub 2013 Mar 11.

Ecology of potential West Nile virus vectors in Southeastern Louisiana: enzootic transmission in the relative absence of Culex quinquefasciatus.

Author information

  • 1Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA. mjg9@cdc.gov

Abstract

A study of West Nile virus (WNV) ecology was conducted in St. Tammany Parish, Louisiana, from 2002 to 2004. Mosquitoes were collected weekly throughout the year using Centers for Disease Control and Prevention (CDC) light traps placed at 1.5 and 6 m above the ground and gravid traps. A total of 379,466 mosquitoes was collected. WNV was identified in 32 pools of mosquitoes comprising four species; 23 positive pools were from Culex nigripalpus collected during 2003. Significantly more positive pools were obtained from Cx. nigripalpus collected in traps placed at 6 m than 1.5 m that year, but abundance did not differ by trap height. In contrast, Cx. nigripalpus abundance was significantly greater in traps placed at 6 m in 2002 and 2004. Annual temporal variation in Cx. nigripalpus peak seasonal abundance has important implications for WNV transmission in Louisiana. One WNV-positive pool, from Cx. erraticus, was collected during the winter of 2004, showing year-round transmission. The potential roles of additional mosquito species in WNV transmission in southeastern Louisiana are discussed.

PMID:
23478575
[PubMed - indexed for MEDLINE]
PMCID:
PMC3752769
Free PMC Article
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5.
J Med Entomol. 2012 Nov;49(6):1189-97.

Sequence, secondary structure, and phylogenetic analyses of the ribosomal internal transcribed spacer 2 (ITS2) in members of the North American Signifera Group of Orthopodomyia (Diptera: Culicidae).

Author information

  • 1Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA. bdbyrd@email.wcu.edu

Abstract

Mosquitoes of the genus Orthopodomyia (Diptera: Culicidae) are little known and of uncertain epidemiological importance. In the United States, there are three Orthopodomyia species (i.e., Or. signifera (Coquillett), Or. alba Baker, and Or. kummi Edwards); they are all members of the Signifera Group based on the current morphological taxonomy. In the course of identifying recently collected specimens, a problem was found with the current key morphological characters for separating the fourth instar larvae of Or. signifera and Or. kummi. Internal transcribed spacer two sequences of the rDNA were obtained to resolve the identities. The Orthopodomyia internal transcribed spacer two ranged in size from 193 (Or. kummi) to 244 bp (Or. signifera) (mean = 218 bp) and were slightly Adenine/Thymine enriched (44.7% Guanine/Cytosine on average). Putative secondary structures reveal structural homologies (four domains) consistent between species that also feature conserved sequences specific to mosquitoes (e.g., a conserved motif on the 3' aspect of the longest helix: GARTACATCC). Sequence analyses suggest that in certain areas of southwestern North America, hybridization may occur between Or. kummi and Or. signifera. Furthermore, our analyses confirm that Or. californica (a junior synonym of Or. signifera) is indeed Or. signifera. To our knowledge, this is the first sequence-based phylogenetic and molecular analysis of the Orthopodomyia.

PMID:
23270146
[PubMed - indexed for MEDLINE]
6.
Med Vet Entomol. 2013 Sep;27(3):284-97. doi: 10.1111/j.1365-2915.2012.01048.x. Epub 2012 Oct 18.

Proof of concept for a novel insecticide bioassay based on sugar feeding by adult Aedes aegypti (Stegomyia aegypti).

Author information

  • 1Department of Entomology, North Carolina State University, Raleigh, NC 27695, U.S.A.

Abstract

Aedes aegypti L. (Stegomyia aegypti) (Diptera: Culicidae) is the principal vector of dengue and yellow fever viruses in tropical and subtropical regions of the world. Disease management is largely based on mosquito control achieved by insecticides applied to interior resting surfaces and through space sprays. Population monitoring to detect insecticide resistance is a significant component of integrated disease management programmes. We developed a bioassay method for assessing insecticide susceptibility based on the feeding activity of mosquitoes on plant sugars. Our prototype sugar-insecticide feeding bioassay system was composed of inexpensive, disposable components, contained minimal volumes of insecticide, and was compact and highly transportable. Individual mosquitoes were assayed in a plastic cup that contained a sucrose-permethrin solution. Trypan blue dye was added to create a visual marker in the mosquito's abdomen for ingested sucrose-permethrin solution. Blue faecal spots provided further evidence of solution ingestion. With the sugar-insecticide feeding bioassay, the permethrin susceptibility of Ae. aegypti females from two field-collected strains was characterized by probit analysis of dosage-response data. The field strains were also tested by forced contact of females with permethrin residues on filter paper. Dosage-response patterns were similar, indicating that the sugar-insecticide feeding bioassay had appropriately characterized the permethrin susceptibility of the two strains.

© 2012 The Royal Entomological Society.

KEYWORDS:

Aedes aegypti; anthrone; bioassay; insecticide resistance; permethrin; sugar feeding

PMID:
23077986
[PubMed - indexed for MEDLINE]
Icon for Blackwell Publishing
7.
J Med Entomol. 2012 Sep;49(5):1092-102.

Host preference of the arbovirus vector Culex erraticus (Diptera: Culicidae) at Sonso Lake, Cauca Valley Department, Colombia.

Author information

  • 1Department of Tropical Medicine, Tulane University, 1440 Canal St, Suite 2210, New Orleans, LA 70112, USA. ian.mendenhall@duke-nus.edu.sg

Abstract

Culex erraticus (Dyar & Knab) is a competent vector of Eastern equine encephalitis virus and subtype IC Venezuelan equine encephalitis virus, and both St. Louis encephalitis virus and West Nile virus have been isolated from field-collected specimens. Previous bloodmeal analysis studies have shown this species to be a generalist, feeding on a variety of mammals, birds, reptiles, and amphibians. This behavior can bridge arboviral transmission across different vertebrate groups. Our study examined the host preference of Cx. erraticus at Sonso Lake in Colombia. From July to August 2008, blood-engorged mosquitoes were collected from resting boxes, while vertebrate abundance was determined to calculate host preference. Based on mitochondrial DNA analysis of bloodmeals, birds were the predominant hosts (57.6%), followed by mammals (30.8%), and reptiles (6.7%); 9.5% of the bloodmeals were mixed. The most commonly fed upon species were: limpkin, black-crowned night-heron, striated heron, human, and capybara. Forage ratios showed the least bittern, limpkin, Cocoi heron, striated heron, capybara, and black-crowned night heron were preferred hosts across all vertebrates. Of the available avifauna, the least bittern, limpkin, striated heron, Cocoi heron, and black-crowned night heron were preferred, whereas the bare faced ibis, great egret, snowy egret, and cattle egret were under-used. This study shows that while Cx. erraticus is an opportunistic feeder, using diverse vertebrate hosts in the environment, certain avian species are targeted preferentially for bloodmeals.

PMID:
23025191
[PubMed - indexed for MEDLINE]
8.
Malar J. 2012 Jun 10;11:193. doi: 10.1186/1475-2875-11-193.

PCR detection of malaria parasites in desiccated Anopheles mosquitoes is uninhibited by storage time and temperature.

Author information

  • 1Department of Tropical Medicine, Tulane University, New Orleans, LA 70112, USA. mrider@tulane.edu

Abstract

BACKGROUND:

Reliable methods to preserve mosquito vectors for malaria studies are necessary for detecting Plasmodium parasites. In field settings, however, maintaining a cold chain of storage from the time of collection until laboratory processing, or accessing other reliable means of sample preservation is often logistically impractical or cost prohibitive. As the Plasmodium infection rate of Anopheles mosquitoes is a central component of the entomological inoculation rate and other indicators of transmission intensity, storage conditions that affect pathogen detection may bias malaria surveillance indicators. This study investigated the effect of storage time and temperature on the ability to detect Plasmodium parasites in desiccated Anopheles mosquitoes by real-time polymerase chain reaction (PCR).

METHODS:

Laboratory-infected Anopheles stephensi mosquitoes were chloroform-killed and stored over desiccant for 0, 1, 3, and 6 months while being held at four different temperatures: 28, 37, -20 and -80°C. The detection of Plasmodium DNA was evaluated by real-time PCR amplification of a 111 base pair region of block 4 of the merozoite surface protein.

RESULTS:

Varying the storage time and temperature of desiccated mosquitoes did not impact the sensitivity of parasite detection. A two-way factorial analysis of variance suggested that storage time and temperature were not associated with a loss in the ability to detect parasites. Storage of samples at 28°C resulted in a significant increase in the ability to detect parasite DNA, though no other positive associations were observed between the experimental storage treatments and PCR amplification.

CONCLUSIONS:

Cold chain maintenance of desiccated mosquito samples is not necessary for real-time PCR detection of parasite DNA. Though field-collected mosquitoes may be subjected to variable conditions prior to molecular processing, the storage of samples over an inexpensive and logistically accessible desiccant will likely ensure accurate assessment of malaria parasite presence without diminishing PCR-detection of parasites in mosquitoes stored for at least six months.

PMID:
22682161
[PubMed - indexed for MEDLINE]
PMCID:
PMC3405449
Free PMC Article
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9.
J Med Entomol. 2012 May;49(3):522-34.

Genetic structure of Culex erraticus populations across the Americas.

Author information

  • 1Department of Tropical Medicine, Tulane University, New Orleans, LA 70112, USA. ian.mendenhall@duke-nus.edu.sg

Abstract

Culex erraticus (Dyar & Knab) is a potential competent vector for several arboviruses such as Eastern and Venezuelan equine encephalitis viruses and West Nile virus. It therefore may play a role in the maintenance and spread of viral populations in areas of concern, including the United States where it occurs in >33 states. However, little information is available on potential barriers to movement across the species' distribution. Here, we analyze genetic variation among Cx. erraticus collected from Colombia, Guatemala, and nine locations in the United States to better understand population structure and connectivity. Comparative sequence analysis of the second internal transcribed spacer and mitochondrial NADH dehydrogenase genes identified two major lineages of sampled populations. One lineage represented the central and eastern United States, whereas the other corresponded to Central America, South America, and the western United States. Hierarchical analysis of genetic variation provided further evidence of regional population structure, although the majority of genetic variation was found to reside within populations, suggestive of large population sizes. Although significant physical barriers such as the Chihuahuan Desert probably constrain the spread of Cx. erraticus, large population sizes and connectivity within regions remain important risk factors that probably contribute to the movement of arboviruses within and between these regions.

PMID:
22679859
[PubMed - indexed for MEDLINE]

Publication Types, MeSH Terms, Secondary Source ID, Grant Support

Publication Types

MeSH Terms

Secondary Source ID

Grant Support

10.
Trans R Soc Trop Med Hyg. 2012 Jun;106(6):387-9. doi: 10.1016/j.trstmh.2012.02.007. Epub 2012 Apr 20.

Yellow fever virus susceptibility of two mosquito vectors from Kenya, East Africa.

Author information

  • 1Department of Tropical Medicine, Tulane University, 1440 Canal Street Suite 2210-SL17, New Orleans, Louisiana 70112, USA. brett.ellis@duke-nus.edu.sg

Abstract

Yellow fever is an unpredictable disease of increasing epidemic threat in East Africa. Aedes (Stegomyia) aegypti has never been implicated as a vector in this region and recent outbreaks have involved a newly emerging virus genotype (East African). To better understand the increasing epidemic risk of yellow fever in East Africa, this study is the first to investigate the vector competence for an emerging East African virus genotype in Kenyan A. aegypti sensu latu (s.l) and A. (Stegomyia) simpsoni s.l. mosquito species. Using first filial generation mosquitoes and a low passage yellow fever virus, this study demonstrated that although A. aegypti s.l. is a competent vector, A. simpsoni s.l. is likely a more efficient vector.

Copyright © 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

PMID:
22521217
[PubMed - indexed for MEDLINE]
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11.
J Med Entomol. 2011 Nov;48(6):1210-3.

Disproportionate mosquito feeding on aggregated hosts.

Author information

  • 1Department of Epidemiology, Tulane University, School of Public Health and Tropical Medicine, 1400 Canal Street, New Orleans, LA 70112, USA. ivo.foppa@gmail.com

Abstract

Despite the importance of per-capita feeding rates for mosquito-borne transmission dynamics, the relationship between host aggregation and per-capita feeding rates remains poorly characterized. We conducted indoor experiments to investigate how Culex quinquefasciatus (Say) mosquitoes distribute their blood feeding on variably aggregated domestic chickens (Callus gallus domesticus L.) (one chicken vs. a flock of seven to nine birds). Mosquitoes were always more likely to feed on the larger chicken group; yet, the single chicken tended to be fed on at a higher per-capita rate. When 10 chickens were available the feeding intensity was 4.5 times higher for the single chicken compared with the flock. We conclude that more highly aggregated hosts may experience lower exposure to mosquito bites than less aggregated hosts.

PMID:
22238881
[PubMed - indexed for MEDLINE]
12.
J Med Entomol. 2011 Sep;48(5):1091-4.

High Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) prevalence in Triatoma sanguisuga (Hemiptera: Redviidae) in southeastern Louisiana.

Author information

  • 1Department of Tropical Medicine, Tulane University, New Orleans, LA 70112, USA.

Abstract

From May through November 2007, intensive weekly surveys at the site of a previously reported autochthonous human case of Chagas parasite infection resulted in the collection of 298 Triatoma sanguisuga (Leconte) specimens, of which 60.4% (180) were polymerase chain reaction positive for Trypanosoma cruzi Chagas. All were adults, in a ratio of approximately 1:1 female to male, indicating that the domicile was not colonized, but was a destination for these host-seeking adults. We report on seasonal activity pattern, T. cruzi prevalence in T. sanguisuga, and attempts at insect exclusion and control at the case residence.

PMID:
21936329
[PubMed - indexed for MEDLINE]
PMCID:
PMC3544525
Free PMC Article
Icon for PubMed Central
13.
PLoS One. 2011;6(9):e24409. doi: 10.1371/journal.pone.0024409. Epub 2011 Sep 6.

Bacteria stimulate hatching of yellow fever mosquito eggs.

Author information

  • 1Department of Entomology, North Carolina State University, Raleigh, North Carolina, United States of America. loganathan_ponnusamy@ncsu.edu

Abstract

BACKGROUND:

Aedes aegypti Linnaeus is a peridomestic mosquito that lays desiccation-resistant eggs in water-filled human-made containers. Previous investigations connected egg hatching with declining dissolved oxygen (DO) that is associated with bacterial growth. However, past studies failed to uncouple DO from other potential stimulatory factors and they contained little quantitative information about the microbial community; consequently, a direct role for bacteria or compounds associated with bacteria in stimulating egg hatching cannot be dismissed.

METHODOLOGY/PRINCIPAL FINDINGS:

Environmental factors stimulating hatch of Ae. aegypti eggs were investigated using non-sterile and sterile white oak leaf (WOL) infusions and a bacterial culture composed of a mix of 14 species originally isolated from bamboo leaf infusion. In WOL infusion with active microbes, 92.4% of eggs hatched in 2-h at an average DO concentration of 2.4 ppm. A 24-h old bacterial culture with a DO concentration of 0.73 ppm also stimulated 95.2% of eggs hatch within 1-h. In contrast, only 4.0% of eggs hatched in sterile infusion, whose DO averaged 7.4 ppm. Effects of bacteria were uncoupled from DO by exposing eggs to bacterial cells suspended in NaCl solution. Over a 4-h exposure period, 93.8% of eggs hatched while DO concentration changed minimally from 7.62 to 7.50 ppm. Removal of bacteria by ultra-filtration and cell-free filtrate resulted in only 52.0% of eggs hatching after 4-h at an average DO concentration of 5.5 ppm.

CONCLUSIONS/SIGNIFICANCE:

Collectively, the results provide compelling evidence that bacteria or water-soluble compounds secreted by bacteria, not just low DO concentration, stimulate hatching of Ae. aegypti eggs. However, the specific cues involved remain to be identified. These research findings contribute new insight into an important aspect of the oviposition biology of Ae. aegypti, a virus vector of global importance, providing the basis for a new paradigm of environmental factors involved in egg hatching.

PMID:
21915323
[PubMed - indexed for MEDLINE]
PMCID:
PMC3167859
Free PMC Article
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14.
J Am Mosq Control Assoc. 2011 Jun;27(2):148.

First record of Culex (Anoedioporpa) restrictor from Colombia.

Author information

  • 1Department of Tropical Medicine, Tulane University, New Orleans, LA 70112, USA.

Abstract

We report the first record of Culex (Anoedioporpa) restrictor collected from a tree hole in the Cauca Valley, Colombia, in 2006.

PMID:
21805847
[PubMed - indexed for MEDLINE]
15.
J Med Entomol. 2010 Nov;47(6):1156-63.

Antibody response against Anopheles albimanus (Diptera: Culicidae) salivary protein as a measure of mosquito bite exposure in Haiti.

Author information

  • 1Department of Tropical Medicine, SPHTM, Tulane University, New Orleans, LA 70112, USA. blondono@tulane.edu

Abstract

Antibodies against arthropod saliva have shown to be a good marker of bite exposure. Because Anopheles albimanus Wiedemann (Diptera: Culicidae) is the principal malaria vector in Haiti, we evaluated the immune response against salivary gland extract (SGE) of this species in malaria-positive and malaria-negative subjects from this country. The results showed that the level of anti-SGE immunoglobulin (Ig)G antibodies was higher in patients with clinical malaria than those in malaria uninfected people living in the same region. In addition, a significant positive correlation between the level of anti-An. albimanus IgG and IgM antibody levels was observed. These results suggest that antibodies against An. albimanus saliva, especially IgG, are useful markers of mosquito bite exposure in Haiti.

PMID:
21175067
[PubMed - indexed for MEDLINE]
16.
J Chem Ecol. 2010 Jul;36(7):709-19. doi: 10.1007/s10886-010-9806-2. Epub 2010 Jun 3.

Oviposition responses of the mosquitoes Aedes aegypti and Aedes albopictus to experimental plant infusions in laboratory bioassays.

Author information

  • 1Department of Entomology, North Carolina State University, Box 7647, Raleigh, NC 27695, USA.

Abstract

Attraction of the mosquitoes Aedes aegypti and Ae. albopictus to plant infusions was evaluated by using a modified sticky-screen bioassay that improved the resolution of mosquito responses to odorants. Under bioassay conditions, solid-phase microextraction-gas chromatographic analyses of the volatile marker chemical indole showed that odorants diffused from bioassay cups, forming a concentration gradient. Infusions were prepared by separately fermenting senescent leaves of eight plant species in well water. Plant infusions were evaluated over an 8-fold range of leaf biomass and/or a 28 d fermentation period. The responses of gravid females of both mosquito species varied with the plant species and biomass of plant materials used to make infusions, and with the length of the fermentation period. Infusions made from senescent bamboo (Arundinaria gigantea) and white oak (Quercus alba) leaves were significantly attractive to both mosquitoes. In general, infusions prepared by using low biomass of plant material over a 7-14 d fermentation period were most attractive to Ae. aegypti. In contrast, Ae. albopictus was attracted to infusions made using a wider range of plant biomass and over a longer fermentation period. Both mosquito species were more attracted to a non-sterile white oak leaf infusion than to white oak leaf infusion that was prepared using sterilized plant material and water, thus suggesting a role for microbial activity in the production of odorants that mediate the oviposition response of gravid mosquitoes.

PMID:
20521087
[PubMed - indexed for MEDLINE]
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17.
Microb Ecol. 2010 Jan;59(1):158-73. doi: 10.1007/s00248-009-9565-1. Epub 2009 Jul 30.

Species composition of bacterial communities influences attraction of mosquitoes to experimental plant infusions.

Author information

  • 1Department of Entomology, North Carolina State University, Raleigh, NC 27695-7613, USA.

Abstract

In the container habitats of immature mosquitoes, catabolism of plant matter and other organic detritus by microbial organisms produces metabolites that mediate the oviposition behavior of Aedes aegypti and Aedes albopictus. Public health agencies commonly use oviposition traps containing plant infusions for monitoring populations of these mosquito species, which are global vectors of dengue viruses. In laboratory experiments, gravid females exhibited significantly diminished responses to experimental infusions made with sterilized white oak leaves, showing that attractive odorants were produced through microbial metabolic activity. We evaluated effects of infusion concentration and fermentation time on attraction of gravid females to infusions made from senescent bamboo or white oak leaves. We used plate counts of heterotrophic bacteria, total counts of 4',6-diamidino-2-phenylindole-stained bacterial cells, and 16S ribosomal DNA (rDNA) polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) to show that changes in the relative abundance of bacteria and the species composition of bacterial communities influenced attraction of gravid A. aegypti and A. albopictus mosquitoes to infusions. DGGE profiles showed that bacterial species composition in infusions changed over time. Principal components analysis indicated that oviposition responses to plant infusions were in general most affected by bacterial diversity and abundance. Analysis of bacterial 16S rDNA sequences derived from DGGE bands revealed that Proteobacteria (Alpha-, Beta-, Delta-, and Gamma-) were the predominant bacteria detected in both types of plant infusions. Gravid A. aegypti were significantly attracted to a mix of 14 bacterial species cultured from bamboo leaf infusion. The oviposition response of gravid mosquitoes to plant infusions is strongly influenced by abundance and diversity of bacterial species, which in turn is affected by plant species, leaf biomass, and fermentation time.

PMID:
19641948
[PubMed - indexed for MEDLINE]
Icon for Springer
18.
Proc Natl Acad Sci U S A. 2008 Jul 8;105(27):9262-7. doi: 10.1073/pnas.0802505105. Epub 2008 Jul 7.

Identification of bacteria and bacteria-associated chemical cues that mediate oviposition site preferences by Aedes aegypti.

Author information

  • 1Department of Entomology and W. M. Keck Center for Behavioral Biology, Box 7613, North Carolina State University, Raleigh, NC 27695-7613, USA.

Abstract

The yellow fever mosquito, Aedes aegypti, the global vector of dengue and yellow fever, is inexorably linked to water-filled human-made containers for egg laying and production of progeny. Oviposition is stimulated by cues from water containers, but the nature and origin of these cues have not been elucidated. We showed that mosquito females directed most of their eggs to bamboo and white-oak leaf infusions, and only a small fraction of the eggs were laid in plain water containers. In binary choice assays, we demonstrated that microorganisms in leaf infusions produced oviposition-stimulating kairomones, and using a combination of bacterial culturing approaches, bioassay-guided fractionation of bacterial extracts, and chemical analyses, we now demonstrate that specific bacteria-associated carboxylic acids and methyl esters serve as potent oviposition stimulants for gravid Ae. aegypti. Elucidation of these compounds will improve understanding of the chemical basis of egg laying behavior of Ae. aegypti, and the kairomones will likely enhance the efficacy of surveillance and control programs for this disease vector of substantial global public health importance.

PMID:
18607006
[PubMed - indexed for MEDLINE]
PMCID:
PMC2443818
Free PMC Article
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19.
Emerg Infect Dis. 2008 May;14(5):804-7. doi: 10.3201/eid1405.071066.

Increase in West Nile neuroinvasive disease after Hurricane Katrina.

Author information

  • 1Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, 1430 Tulane Ave, SL-17, New Orleans, LA 70112, USA. kcaillou@tulane.edu

Abstract

After Hurricane Katrina, the number of reported cases of West Nile neuroinvasive disease (WNND) sharply increased in the hurricane-affected regions of Louisiana and Mississippi. In 2006, a >2-fold increase in WNND incidence was observed in the hurricane-affected areas than in previous years.

PMID:
18439367
[PubMed - indexed for MEDLINE]
PMCID:
PMC2600257
Free PMC Article
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20.
Microb Ecol. 2008 Nov;56(4):593-603. doi: 10.1007/s00248-008-9379-6. Epub 2008 Mar 29.

Diversity of bacterial communities in container habitats of mosquitoes.

Author information

  • 1Department of Entomology, North Carolina State University, Campus Box 7647, Raleigh, NC 27695-7647, USA.

Abstract

We investigated the bacterial diversity of microbial communities in water-filled, human-made and natural container habitats of the mosquitoes Aedes aegypti and Aedes albopictus in suburban landscapes of New Orleans, Louisiana in 2003. We collected water samples from three classes of containers, including tires (n = 12), cemetery urns (n = 23), and miscellaneous containers that included two tree holes (n = 19). Total genomic DNA was extracted from water samples, and 16S ribosomal DNA fragments (operational taxonomic units, OTUs) were amplified by PCR and separated by denaturing gradient gel electrophoresis (DGGE). The bacterial communities in containers represented diverse DGGE-DNA banding patterns that were not related to the class of container or to the local spatial distribution of containers. Mean richness and evenness of OTUs were highest in water samples from tires. Bacterial phylotypes were identified by comparative sequence analysis of 90 16S rDNA DGGE band amplicons. The majority of sequences were placed in five major taxa: Alpha-, Beta- and Gammaproteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and an unclassified group; Proteobacteria and Bacteroidetes were the predominant heterotrophic bacteria in containers. The bacterial communities in human-made containers consisted mainly of undescribed species, and a phylogenetic analysis based on 16S rRNA sequences suggested that species composition was independent of both container type and the spatial distribution of containers. Comparative PCR-based, cultivation-independent rRNA surveys of microbial communities associated with mosquito habitats can provide significant insight into community organization and dynamics of bacterial species.

PMID:
18373113
[PubMed - indexed for MEDLINE]
PMCID:
PMC2904961
Free PMC Article
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Publication Types, MeSH Terms, Substances, Secondary Source ID, Grant Support

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