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 gravidAe. aegypti. Elucidation of these compounds will improve understanding of the chemical basis of egg laying behavior ofAe. aegypti, and the kairomones will likely enhance the efficacy of surveillance and control programs for this disease vector of substantial global public health importance.

Ixodes scapularis is the principal vector of Lyme disease on the East Coast and in the upper Midwest regions of the United States, yet the tick is also present in the Southeast, where Lyme disease is absent or rare. A closely related species, I. affinis , also carries the pathogen in the South but does not seem to transmit it to humans. In order to better understand the geographic diversity of the tick, we analyzed the microbiota of 104 adult I. scapularis and 13 adult I. affinis ticks captured in 19 locations in South Carolina, North Carolina, Virginia, Connecticut, and New York. Initially, ticks from 4 sites were analyzed by 454 pyrosequencing. Subsequently, ticks from these sites plus 15 others were analyzed by sequencing with an Illumina MiSeq machine. By both analyses, the microbiomes of female ticks were significantly less diverse than those of male ticks. The dissimilarity between tick microbiomes increased with distance between sites, and the state in which a tick was collected could be inferred from its microbiota. The genus Rickettsia was prominent in all locations. Borrelia was also present in most locations and was present at especially high levels in one site in western Virginia. In contrast, members of the family Enterobacteriaceae were very common in North Carolina I. scapularis ticks but uncommon in I. scapularis ticks from other sites and in North Carolina I. affinis ticks. These data suggest substantial variations in the Ixodes microbiota in association with geography, species, and sex.

Aedes albopictus (Skuse) (Diptera: Culicidae) is a major nuisance mosquito and a potential arbovirus vector. The host-feeding patterns of Ae. albopictus were investigated during the 2002 and 2003 mosquito seasons in suburban neighborhoods in Wake County, Raleigh, NC. Hosts of blood-fed Ae. albopictus (n = 1,094) were identified with an indirect enzyme-linked immunosorbent assay, by using antisera made in New Zealand White rabbits to the sera of animals that would commonly occur in peridomestic habitats. Ae. albopictus fed predominantly on mammalian hosts (83%). Common mammalian hosts included humans (24%), cats (21%), and dogs (14%). However, a notable proportion (7%) of bloodmeals also was taken from avian hosts. Some bloodmeals taken from birds were identified to species by a polymerase chain reaction-heteroduplex assay (PCR-HDA). Ae. albopictus fed predominantly on chickens and a northern cardinal. PCR-HDA failed to produce detectable products for 29 (58%) of 50 bloodmeals for which DNA had been amplified, indicating that these mosquitoes took mixed bloodmeals from avian and nonavian hosts. Ae. albopictus preference for humans, dogs, and cats was determined by calculating host-feeding indices for the three host pairs based on the proportion of host specific blood-fed mosquitoes collected in relation to the number of specific hosts per residence as established by a door-to-door survey conducted in 2003. Estimates of the average amount of time that residents and their pets (cats and dogs) spent out of doors were obtained. Host-feeding indices based only on host abundance indicated that Ae. albopictus was more likely to feed on domestic animals. However, when feeding indices were time-weighted, Ae. albopictus fed preferentially upon humans. Ae. albopictus blood feeding on humans was investigated using a STR/PCR-DNA profiling technique that involved amplification of three short tandem repeats loci. Of 40 human bloodmeals, 32 (80%) were from a single human, whereas eight (20%) were multiple bloodmeals taken from more than one human host. We conclude that the blood-feeding preference of Ae. albopictus for mammals will limit acquisition of arboviruses by this species from infected avian amplification hosts. This feeding preference likely limits the vector potential of Ae. albopictus for North American arboviruses.

A novel species,Swaminathania salitoleransgen. nov., sp. nov., was isolated from the rhizosphere, roots and stems of salt-tolerant, mangrove-associated wild rice (Porteresia coarctataTateoka) using nitrogen-free, semi-solid LGI medium at pH 5·5. Strains were Gram-negative, rod-shaped and motile with peritrichous flagella. The strains grew well in the presence of 0·35 % acetic acid, 3 % NaCl and 1 % KNO₃, and produced acid froml-arabinose,d-glucose, glycerol, ethanol,d-mannose,d-galactose and sorbitol. They oxidized ethanol and grew well on mannitol and glutamate agar. The fatty acids 18 : 1ω7c/ω9t/ω12tand 19 : 0cycloω8cconstituted 30·41 and 11·80 % total fatty acids, respectively, whereas 13 : 1 AT 12–13 was found at 0·53 %. DNA G+C content was 57·6–59·9 mol% and the major quinone was Q-10. Phylogenetic analysis based on 16S rRNA gene sequences showed that these strains were related to the generaAcidomonas,Asaia,Acetobacter,Gluconacetobacter,GluconobacterandKozakiain theAcetobacteraceae. Isolates were able to fix nitrogen and solubilized phosphate in the presence of NaCl. Based on overall analysis of the tests and comparison with the characteristics of members of theAcetobacteraceae, a novel genus and species is proposed for these isolates,Swaminathania salitoleransgen. nov., sp. nov. The type strain is PA51^T(=LMG 21291^T=MTCC 3852^T).

Ticks are important vectors for many emerging pathogens. However, they are also infected with many symbionts and commensals, often competing for the same niches. In this paper, we characterize the microbiome of Amblyomma americanum (Acari: Ixodidae), the lone star tick, in order to better understand the evolutionary relationships between pathogens and nonpathogens. Multitag pyrosequencing of prokaryotic 16S rRNA genes (16S rRNA) was performed on 20 lone star ticks (including males, females, and nymphs). Pyrosequencing of the rickettsial sca0 gene (also known as ompA or rompA ) was performed on six ticks. Female ticks had less diverse microbiomes than males and nymphs, with greater population densities of Rickettsiales . The most common members of Rickettsiales were “ Candidatus Rickettsia amblyommii” and “ Candidatus Midichloria mitochondrii.” “ Ca . Rickettsia amblyommii” was 2.6-fold more common in females than males, and there was no sequence diversity in the sca0 gene. These results are consistent with a predominantly vertical transmission pattern for “ Ca . Rickettsia amblyommii.”

In North Carolina, reported human cases of tick-borne illness, specifically Rocky Mountain spotted fever, have escalated over the past decade. To determine the relative abundance of vectors and to estimate the risk of acquiring a tick-borne illness in peri-residential landscapes, ticks were collected in Chatham County, a typical Piedmont county and, samples of the ticks were tested for infection with selected bacterial pathogens using real-time quantitative polymerase chain reaction assays. Ticks ( n = 3746) were collected by flagging vegetation at 26 sites from April to July 2006. The predominant questing tick was Amblyomma americanum (98.5%) with significantly fewer Dermacentor variabilis (1.0%) and Ixodes scapularis (0.5%) collected. Spotted fever group (SFG) rickettsiae were detected in 68.2% of 1590 A. americanum with 56.4% of the molecular isolates identified as Rickettsia amblyommii , an informally named member of the SFG rickettsiae. Comparatively, smaller numbers of A. americanum contained Ehrlichia chaffeensis (1.8%) and Borrelia lonestari (0.4%). Of 15 I. scapularis nymphs tested, 6 (40%) were positive for Borrelia burgdorferi sensu lato. Seven (19.4%) of 36 adult D. variabilis tested positive for Rickettsia montanensis , 4 (11.1%) were positive for R . amblyommii , and 5 (13.9%) were infected with unidentified species of SFG rickettsiae. The tick population in Chatham County contains a diverse array of microbes, some of which are known or potential pathogens. Highest attack rates would be expected from A . americanum ticks, and highest potential risk of infection with a tick-transmitted agent would be to rickettsial organisms, particularly R . amblyommii . Accordingly, longitudinal eco-epidemiology investigations are needed to determine the public health importance of A . americanum infected with rickettsial organisms.