Discarded vehicle tires are a common habitat for a variety of container mosquito species. I reviewed the literature from the last 50 yr on mosquitoes collected within tires in the eastern United States with four objectives: to examine the historical and contemporary issues of tires as a habitat for mosquitoes, to identify tire-inhabiting species, to summarize findings from studies that focused on biotic and abiotic characteristics of tires, and to offer future directions to aid our understanding of tire-inhabiting mosquitoes. Thirty-two species have been documented, including seven invasives, with the most frequently encountered being Aedes triseriatus, Ae. albopictus, Ae. atropalpus, Culex restuans, Cx. pipiens, Cx. territans, Anopheles punctipennis, and Toxorhynchites rutilus. The proclivity of these species to occupy small containers is one possible explanation for their occurrence in tires. The native species Ae. triseriatus was abundant and the most often collected, particularly in central and northern regions, whereas the invasive Ae. albopictus was most abundant in the south. One half of the studies investigating aspects of the tire environment compared mosquito populations between sunlit and shaded tires, with the general finding that this factor alone led to dramatic differences in larval species composition and abundance patterns. Less frequently investigated factors, e.g., tire orientation, detritus, and proximity to humans, also were found to affect patterns of occupancy by mosquitoes. For the future, I suggest more surveys are needed in understudied areas, as well as quantitative experiments to determine habitat associations and community dynamics in tires, which are especially necessary to assist in understanding invasions. Discarded tires are important for studies of vector dynamics, because of their abundance near human populations and because they expand the habitat range of mosquitoes that vector pathogens.

Scanning electron microscopy documentation of the first instar of Musca domestica L. is presented for the first time. The following morphological structures are documented: antenna, maxillary palpus, facial mask, spinulation, posterior spiracles, anal pad, and integumental micropores. Morphology of the first-instar larva of M. domestica is discussed in light of existing knowledge about early larval instars of Calyptrata flies.

Introduced mosquito-borne pathogens avian malaria (Plasmodium relictum Grassi and Feletti) and avian pox virus (Avipoxvirus) have been implicated in the past extinctions and declines of Hawaiian avifauna and remain significant obstacles to the recovery and restoration of endemic Hawaiian birds. Effective management of avian disease will require extensive mosquito control efforts that are guided by the local ecology of the vector Culex quinquefasciatus Say (Diptera: Culicidae). During October and November 1997 and September through November 1998 five mark–release–recapture experiments with laboratory-reared Cx. quinquefasciatus were conducted in a native rain forest on Hawaii Island. Of the overall 66,047 fluorescent dye-marked and released females, 1,192 (1.8%) were recaptured in 43–52 CO₂-baited traps operated for 10–12-d trapping periods. Recaptured mosquitoes were trapped in all directions and at distances up to 3 km from the release site. The cumulative mean distance traveled (MDTs) over the trapping period ranged from a high of 1.89 km after 11 d (September 1998) to a low of 0.81 km after 11 d (November 1998). Released mosquitoes moved predominately in a downwind direction and they seemed to use forestry roads as dispersal corridors. Applying an estimated MDT of 1.6 km to a geographical information system-generated map of the Hakalau Forest National Wildlife Refuge clearly demonstrated that the effective refuge area could be reduced 60% by mosquitoes infiltrating into managed refuge lands. These findings should have significant implications for the design of future refuges and development of effective mosquito-borne avian disease control strategies.

During autumn, a large number of adult Culex tritaeniorhynchus Giles suddenly appeared at a park in urban Tokyo. A total of 14,069 females and 2,802 males were collected at rest by sweeping from April to November 2007, of which 99.8% of the females were collected from late September to November. The appearance of a large number of Cx. tritaeniorhynchus started on 22 September, peaked at 1,062 per collection/hr on 13 October, and gradually decreased by the end of November. A total of 565 females were marked and released on 3 October, and the total number of females in the park was estimated to be 545,225 ± 157,392 by the Lincoln index. No females were collected by human landing collections, and the parous rate of females collected by sweeping was 4.4% (41/936). Dissections showed that 85.7% (120/140) of these females were in reproductive diapause, with an ovariole stage of N or I and a primary over secondary follicular ratio ≤1.5. From January to early April 2008, only 10 overwintering Cx. tritaeniorhynchus females were collected resting. These results indicated that these females were in reproductive diapause and that some overwintered in this urban setting. This is the first field evidence of prediapause seasonal migration of this species from breeding sites to overwintering sites.

Aedes albopictus (Skuse) is a principal nuisance mosquito species and a potential arbovirus vector throughout its geographic range in the United States. This species lays eggs, and progeny complete development in water-filled containers that are discarded in suburban landscapes. Source reduction of containers, achieved through environmental sanitation, was used to experimentally manipulate mosquito production to gain insight into the spatial structure of the population of immature Ae. albopictus. Our studies were conducted in suburban landscapes in Raleigh, NC, during the 2002 and 2003 mosquito seasons. Spatial analyses, using estimates of the mean and total standing crop of pupae and counts of the numbers of mosquito-positive containers, showed that the distribution of mosquito production was not spatially dependent on a neighborhood-wide basis. However, in all neighborhoods, mosquito production was clustered in at least one and often more than one adjacent residence. Point pattern analyses that considered only the presence or absence of pupae showed that pupae-positive residences were dispersed throughout neighborhoods receiving monthly source reduction treatments and clustered throughout control neighborhoods, indicating that source reduction affected the spatial distribution of pupae. Conversely, spatial analyses based on the presence or absence of larvae and pupae showed that mosquito production was randomly distributed among residences in both control and source reduction neighborhoods, showing that Ae. albopictus recolonized containers within several weeks after source reduction was implemented. Knowledge of the spatial distribution of production sites would allow management efforts for Ae. albopictus to be targeted to residences supporting high levels of mosquito production.

Aedes albopictus (Skuse) and Aedes japonicus (Theobald) are two of the most recent and widespread invasive mosquito species to have become established in the United States. The two species co-occur in water-filled artificial containers, where crowding and limiting resources are likely to promote inter- or intraspecific larval competition. The performance of northern Virginia populations of Ae. japonicus and Ae. albopictus competing as larvae under field conditions was evaluated. Per capita rates of population increase for each species were estimated, and the effects of species composition and larval density were determined. In water-containing cups provided with oak leaves, Ae. albopictus larvae exhibited a competitive advantage over Ae. japonicus as a consequence of higher survivorship, shorter developmental time, and a significantly higher estimated population growth rate under conditions of interspecific competition. Intraspecific competition constrained population performance of Ae. albopictus significantly more than competition with Ae. japonicus. In the context of the Lotka-Volterra model of competition, these findings suggest competitive exclusion of Ae. japonicus in those habitats where this species co-occurs with Ae. albopictus.

The French 2-tier box trap was evaluated in northwestern Florida to determine its attractiveness to host-seeking tabanids (Diptera) when baited with either CO₂ alone; a 4:1:8 mixture of octenol, 3-n-propylphenol, and 4-methylphenol; or a combination of CO₂ plus 4:1:8 mixture. Six genera representing 43 species were obtained from this trap. Chrysops and Tabanus made up 10.3 and 87.4% of the total, respectively, with Chrysops celatus Pechuman and Tabanus pallidescens Philip as the predominate species from these two genera. CO₂ alone and in combination with the octenol/phenol mixture enhanced overall tabanid collections three- to four-fold compared with no odor. Generally, more species were collected in the top tier of the French 2-tier trap regardless of treatment. Those species that showed a significant difference between top and bottom tiers in traps without odors continued this trend when traps were baited with the semiochemicals. However, Tabanus mixis Philip showed no tier preference in traps baited by CO₂ alone, whereas Tabanus lineola F. showed no stratification difference with or without odors.

Mating in Anopheles gambiae has been observed only in outdoor swarms. Here we evaluate whether mating also occurs indoors. Mark-release-recapture of virgin males and females in natural houses showed that mating occurred over a single day even when mosquitoes can leave the house through exit traps and without adaptation to laboratory conditions. In these experiments, insemination rate in the M molecular form of An. gambiae (and An. arabiensis) was higher than that of the S form (15 versus 6%). Under these conditions, smaller females of the M form mated more frequently than larger females of that form. Sampling mosquitoes throughout the day showed that both sexes enter houses around sunrise and leave around sunset, staying indoors together from dawn to dusk. In an area dominated by the M form, the daily rate of insemination in samples from exit traps was ≈5% higher than in those from entry traps, implying that mating occurred indoors. Importantly, frequency of cross mating between the molecular forms was as high as that between members of the same form, indicating that, indoors, assortative mating breaks down. Altogether, these results suggest that indoor mating is an alternative mating strategy of the M molecular form of An. gambiae. Because naturally occurring mating couples have not yet been observed indoors, this conclusion awaits validation.

The phlebotomine sand flies Lutzomyia pia (Fairchild & Hertig 1961) and Lutzomyia tihuiliensis Le Pont, Torrez-Espejo & Dujardin 1997 (Diptera: Psychodidae) belong to the pia series of the Lu. verrucarum species group, which includes several species that bite humans in Andean foci of leishmaniasis. The females of these two species exhibit isometry and isomorphism in anatomical structures of the head and terminalia commonly used in taxonomic identification of sand flies. They can only be differentiated based on subtle differences in the pigmentation of the pleura. In Lu. tihuiliensis, this is restricted to the basal portions of the katepimeron and katepisternum, whereas in Lu. pia both structures are totally pigmented. Taking into account the subtle morphological differences between these species, the objective of the current study was to evaluate the specific taxonomic status of Lu. tihuiliensis with respect to Lu. pia. A 475-bp portion of the mitochondrial genome was sequenced, composed of the 3′ end of the cytochrome b gene, intergenic spacer 1, the transfer RNA gene for serine, intergenic spacer 2, and the 3′ end of the gene NAD dehydrogenase 1. Genetic analysis confirms that Lu. tihuiliensis and Lu. pia constitute two distinct species and this is supported by four strong lines of evidence, i.e., the paired genetic distances, size differences and amino acid composition of the cytochrome b protein, presence and absence of intergenic spacer one and divergence observed in the sequence of the transfer RNA gene for serine. It also confirms the validity of the pleural pigmentation pattern as a species diagnostic character and the importance of performing a detailed examination of this character during morphological determination of phlebotomine sand flies in the series pia.

Triatoma infestans (Klug) is the main vector of Trypanosoma cruzi, etiologic agent of Chagas disease. The phenotype of the species varies at different geographic scales. The objective of this study was to compare the antennal phenotype of spatially close T. infestans populations and to evaluate its usefulness as a marker of exchange of individuals between populations. The antennal phenotype of 190 T. infestans from Argentina and Bolivia was analyzed using uni- and multivariate techniques. This study shows heterogeneity of the antennal phenotypes of closely related T. infestans populations living in different habitats. Specimens collected in a goat corral and a rabbit cage in La Rioja (Argentina) were dissimilar to the specimens collected in the nearby intradomestic environment. Similarly, specimens from peridomestic corrals in Cochabamba (Bolivia) were different from the intradomestic and sylvatic specimens, indicating some degree of isolation between these populations. In contrast, T. infestans collected in chicken coops and the intradomestic environment were similar, in all studied regions, suggesting a frequent exchange of individuals between the two habitats and/or because of the similarity of the habitat due to the presence of chickens in the intradomestic environment. We propose that each habitat affects in a particular mode the insect morphology and these changes could be used to identify recolonizing T. infestans. These results support the hypothesis of different degrees of isolation between intradomestic and peridomestic habitats. Within this context, special attention should be given to chicken coops and other close peridomestic structures in relation to the recolonization process of domestic habitats by T. infestans.

The family Calliphoridae consists of myiasis-causing flies, including species of economic, forensic, and medical importance. In this study, the complete control regions (CRs) of mitochondrial DNA from 15 calliphorid species were sequenced and structurally characterized. The CRs had a high content of adenines (A) and thymines (T) and varied in length from 854 to 2,018 bp, showing intraspecific variations in sequence and length. Two major domains were identified: the conserved domain containing conserved sequence blocks and cis-regulatory structures that may be related to the transcription and the origin of replication of mitochondrial DNA, and the variable domain, containing high sequence and length variation. Within the variable domain, duplication of the tRNA^Ile gene, previously reported for three Chrysomya species, was identified in two more species of this genus and in two species of two other genera. The structural characterization shows the plasticity of the mitochondrial genome in dipterans. The organizational similarities of the duplicated region found in different species and the possible origin of the duplicated genes are discussed.

A population of Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae), designated Coatzacoalcos, sampled from a ranch near Veracruz, Mexico, was found to possess a high level of resistance to pyrethroid-based acaricides. Bioassay and biochemical and molecular analysis had previously shown that resistance in this population could primarily be attributed to expression of a highly active metabolic esterase designated CzEST9. We cloned and sequenced the entire CzEST9 coding region, including introns and >1.0 kb upstream from the transcription start site, and we compared the upstream region sequence between individual resistant and susceptible ticks from several populations with different pyrethroid resistance characteristics. In the 1.0-kb upstream region sequence, four variant nucleotides were found, and a TGA trinucleotide occurred as either four, five, or nine tandem repeats. However, none of these promoter region sequence differences could be clearly associated with a pyrethroid-resistant phenotype; thus, we concluded that differences in gene promoter sequence were not responsible for the pyrethroid resistance mechanism in the Cz strain. CzEST9 was expressed in recombinant Escherichia coli and Pichia pastoris systems and esterase activity was obtained in recombinant CzEST9 from the P. pastoris system.

We used an expressed sequence tag approach to initiate a study of the genome of the horn fly, Hematobia irritans (L.) (Diptera: Muscidae). Two normalized cDNA libraries were synthesized from RNA isolated from embryos and first instars from a field population of horn flies. Approximately 10,000 clones were sequenced from both the 5′ and 3′ directions. Sequence data from each library was assembled into a database of tentative consensus sequences (TCs) and singletons and used to search public protein databases and annotate the sequences. Additionally, the sequences from both the egg and larval libraries were combined into a single database consisting of 16,702 expressed sequence tags (ESTs) assembling into 2886 TCs and 1,522 singleton entries. Several sequences were identified that may have roles in the horn fly’s resistance to insecticides. The availability of this database will facilitate the design of microarray and other experiments to study horn fly gene expression on a larger scale than previously possible. This would include studies designed to investigate metabolic-based insecticide resistance, identify novel antigens for vaccine-based control approaches, and discover new proteins to serve as targets for new pesticide development.

Insecticide resistance in Pediculus humanus capitis De Geer 1778 (Phthiraptera: Pediculidae) from different countries has been well documented in the last years. Otherwise, little research has been reported about insecticide resistance in insect embryos and none in human louse embryos. In this work, we studied insecticide resistance in eggs of three head lice populations whose pyrethroid resistance was shown in adults and nymphs compared with a susceptible laboratory body louse strain. All head louse populations showed high permethrin resistance in eggs. Levels of permethrin resistance (LCRs) assessed in eggs by immersion technique were higher than those previously reported for the corresponding populations of adults by topical application. Comparison of LCR values for different populations showed that there was a direct relationship between the resistance levels assessed in eggs and those in adults. All permethrin-resistant eggs showed high resistance to d-phenothrin and dichloro-diphenyl-trichloroethane (DDT) and low resistance to carbaryl, which is in common with the resistance profile established for adults and nymphs. The results concerning the high resistance to pyrethroid (permethrin and d-phenothrin) and the cross-resistance to DDT and carbaryl detected in head louse eggs and adults suggested similar resistance mechanisms in eggs and adults of head louse populations from adults.

Male mating competitiveness is a crucial parameter in many genetic control programs including the sterile insect technique (SIT). We evaluated competitiveness of male Anopheles arabiensis Patton as a function of three experimental variables: (1) small or large cages for mating, (2) the effects of either a partially sterilizing (70 Gy) or fully sterilizing (120 Gy) dose, and (3) pupal or adult irradiation. Irradiated males competed for females with an equal number of unirradiated males. Competitiveness was determined by measuring hatch rates of individually laid egg batches. In small cages, pupal irradiation with the high dose resulted in the lowest competitiveness, whereas adult irradiation with the low dose gave the highest, with the latter males being equal in competitiveness to unirradiated males. In the large cage, reduced competitiveness of males irradiated in the pupal stage was more pronounced compared with the small cage; the males irradiated as adults at both doses performed similarly to unirradiated males. Unexpectedly, males irradiated with the high dose performed better in a large cage than in a small one. A high proportion of intermediate hatch rates was observed for eggs collected in the large cage experiments with males irradiated at the pupal stage. It is concluded that irradiation of adult An. arabiensis with the partially sterilizing dose results in the highest competitiveness for both cage designs. Cage size affected competitiveness for some treatments; therefore, competitiveness determined in laboratory experiments must be confirmed by releases into simulated field conditions. The protocols described are readily transferable to evaluate male competitiveness for other genetic control techniques.

Here I report the first findings of consistently high, long-duration efficacy of IR3535 (ethyl butyl acetyl aminopropionate) formulations in the United States. I tested novel, controlled-release formulations of IR3535, at 10% in lotion and at 20% in pump spray and aerosol, against mosquitoes in the field and blacklegged ticks in the laboratory. These were also the first studies to be conducted under the authority of the U.S. Environmental Protection Agency’s Human Studies Rule of 2006, and the protocols underwent science and ethics reviews by five entities. IR3535 is better known in Europe than in North America, having been marketed in the United States only more recently, and there are comparatively few publications on its efficacy. I began with pretrial studies of dosing behavior to compute formula-specific mean dosing rates for the subsequent efficacy trials. Dosing rates were lower than the 1 ml/600 cm rate commonly used to quantify efficacy. Complete protection times ranged from 7.1 to 10.3 h for mosquitoes and from 9.1 to 12.2 h for blacklegged ticks. Long protection duration resulted in many cases being truncated by darkness or eventual subject withdrawal, which suggests that actual protection times were probably greater.

The abundance of Hyalomma lusitanicum ticks in open areas of central Spain is the result of many natural and human factors. Control of tick populations by chemical and other means may be necessary until we can determine the key global factors in this important tick population. Despite many attempts to establish ecological control of ticks, there is little data about the activity of organic acids. This article describes tests on the in vitro toxicity of oxalic acid (OA) against wild H. lusitanicum adult ticks. Serial dilutions of OA dihydrate were prepared in distilled water with 1% of Tween 20. The treatment was applied in three replicates of 10–14 tick/dose from 0 to 1.037 mg OA/tick. Doses >0.311 mg of OA killed all ticks in 24 h. Toxicity of the OA increased over time; therefore, the LD₅₀ decreased from 0.22 mg at 24 h to 0.127 mg at 72 h. The results obtained show the toxicity of OA against adult H. lusitanicum ticks under in vitro conditions. Comparing toxicity in ticks and honey bees, OA seems a relatively safe treatment for nontarget arthropods and a potential alternative for tick population control. However, further research is needed to establish its real effectiveness and applicability under field conditions.

La abundancia de Hyalomma lusitanicum en campo abierto en España se debe a la confluencia de factores ambientales y humanos. Es necesario utilizar métodos de control de la población de garrapatas hasta conseguir restablecer el equilibrio de la población. Aunque los ixódidos se han intentado controlar de forma ecológica, existen pocos datos sobre la utilización de los ácidos orgánicos. En este artículo se evalúa la eficacia in vitro del OA frente a adultos de H. lusitanicum de origen silvestre. Las dosis se aplicaron sobre grupos de 10–14 garrapatas, aplicándose cada dosis en tres réplicas. Las dosis aplicadas fueron de 0,062 a 1,037 mg OA/garrapata. Dosis iguales o superiores a 0,311 mg mataron a todos los individuos a las 24 h. Se observó que la toxicidad del OA aumentó en el tiempo pasando de 0,22 mg a las 24 h a 0,127 mg a las 72 h. Los resultados obtenidos demostraron la eficacia del OA frente a H. lusitanicum in vitro. Comparando la toxicidad en las garrapatas y en las abejas melíferas parece que el tratamiento con este ácido podría ser una alternativa para el control de las primeras y sería relativamente seguro para los artrópodos que no se desea controlar. Es necesario realizar nuevos ensayos para evaluar la autentica eficacia de este tratamiento en condiciones de campo.

Mosquitoes were collected in the Amazon Basin, near Iquitos, Peru, and used in experimental studies to evaluate their susceptibility to strains of eastern equine encephalitis virus (EEEV) that were isolated from mosquitoes captured within 20 km of Iquitos. When fed on hamsters or chickens with a viremia of ≈10⁵ plaque-forming units (PFU) of EEEV/ml, Culex pedroi Sirivanakarn and Belkin, Aedes fulvus (Wiedemann), Psorophora albigenu (Peryassu), and Psorophora ferox (Von Humboldt) were susceptible to infection, whereas none of the Aedes serratus (Theobald), Culex vomerifer Komp, Culex gnomatos Sallum, Huchings, and Ferreira, Culex portesi Senevet and Abonnenc, or Culex coronator Dyar and Knab became infected, even though they fed on the same viremic blood sources. When these mosquito species fed on animals with viremias of ≈10⁸ PFU/ml, Cx. pedroi, Ae. fulvus, Ps. albigenu, and Psorophora cingulata (Fabricius) were the most susceptible. Mosquito species were susceptible to both a lineage II (Brazil-Peru) and a lineage III (Argentina-Panama) isolate of EEEV. This study, combined with the repeated isolation of strains of EEEV from Cx. pedroi captured in the Amazon Basin region of Peru, suggests that Cx. pedroi may be the primary enzootic vector of EEEV in this region.

Ghir-Karzin district is one of the most important endemic foci of visceral leishmaniaisis (VL) in Fars province of southern Iran. To identify the vector(s) of Leishmania in this focus, a total of 2,539 sand flies were collected during June to September 2005. Eleven species (six Phlebotomus and five Sergentomyia) were identified, of which Phlebotomus papatasi Scopoli and Phlebotomus major Annandale were the first (37.4%) and third (11.2%) most common species, respectively. Natural leptomonad infections were observed in two P. papatasi (4.25%) and three P. major (6.65%) specimens on dissection and microscopic examination. Using a Leishmania genus–specific standard polymerase chain reaction (PCR; primers RV1-RV2) and a species-specific nested-PCR (primers LINR4, LIN17, and LIN 19), Leishmania infantum and Leishmania major kinetoplast minicircle DNA was detected in 6 of 72 P. major (8.3%) and 4 of 65 P. papatasi (6.1%), respectively. This is the first detection of L. infantum in P. major, implicating this sand fly as a probable vector of VL in Iran.

Nymphal Ixodes scapularis Say are the principal vectors of Lyme disease spirochetes (Borrelia burgdorferi sensu stricto) in the eastern United States. Physicians frequently face the decision of whether or not to administer prophylactic antibiotics to human tick bite victims in Lyme disease endemic regions, based on the overall probability that such bites will result in infection with B. burgdorferi s.s. We evaluated the transmission dynamics of B. burgdorferi s.s. during the key third day of nymphal I. scapularis feeding, when the risk of transmission rapidly increases. The cumulative probability that 50% of infected ticks transmitted B. burgdorferi s.s. occurred at 68 h of tick attachment and our overall estimate that a human tick bite would result in transmission of B. burgdorferi s.s. was 2.4%.

The vector competence of Verrallina carmenti (Edwards), Verrallina lineata (Taylor), and Mansonia septempunctata (Theobald) (Diptera: Culicidae) from north Queensland, Australia, was tested using two isolates of Ross River virus (family Togaviridae, genus Alphavirus, RRV). All three species were tested using RRV isolate RR102MP (ex-Cairns, Queensland, Australia), whereas Ve. carmenti and Ve. lineata also were tested using RR2186 (ex-Bourke, New South Wales, Australia). Transmission was tested using the capillary tube method, with infection of mosquito bodies and saliva determined using cell culture. Infection with RR102MP resulted in 27.5% of Ve. carmenti, 19.2% of Ve. lineata and 13.3% of Ma. septempunctata transmitting virus. When Ve. carmenti and Ve. lineata were infected with RR2186, transmission rates for both species were generally <10%, although a transmission rate of 25% was recorded for Ve. lineata exposed to high titer virus. These results indicated that the three mosquito species have the potential to contribute to local transmission cycles.

In total, 676 Dermacentor silvarum Olenev (Acari: Ixodidae) from a forest area of Jilin Province in northeastern China were examined by polymerase chain reaction for the presence of spotted fever group (SFG) Rickettsia. The overall positive rate was 10.7%, with a 95% confidence interval from 8.3 to 13.0%. The SFG Rickettsia infection was more prevalent in adults than in nymphs, and in fed ticks obtained from domestic animals than in those collected on vegetation. Sequence analysis of the partial outer membrane protein A gene confirmed the existence of R. sibirica and discovered a novel rickettsial agent in this area, the sequence of which was identical to that of DnS14 genotype Rickettsia previously reported in the former Soviet Union.

Four species of Rickettsia are recognized as endemic to Australia. This study reports the detection of a new spotted fever group Rickettsia in the common marsupial tick Ixodes tasmani Neumann collected from koalas (Phascolarctos cinereus) in Port Macquarie, NSW, Australia. Based on the results of polymerase chain reaction (PCR) amplification of extracted tick DNA with primers targeting the citrate synthase gene (gltA) and the outer membrane proteins A and B (ompA. ompB), Rickettsiae were detected in 22 of 78 I. tasmani tick samples (28.2%). Sequence data obtained for the three genes displayed the closest degree of similarity to Rickettsia heilongjiangiensiss for gltA (99.4%; 331/333 bp), Rickettsia amblyommii for the ompA gene (94.8%; 417/440 bp), and both Rickettsia massiliae and Rickettsia rhipicephali for the ompB gene (97%; 770/803 bp). BLAST and phylogenetic analysis of partial sequences obtained for the three genes were found to have sufficient nucleotide variation from the current recognized Australian species to be considered a distinct spotted fever group Rickettsia.

In response to an epidemic amplification of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), the Sacramento and Yolo Mosquito and Vector Control District (SYMVCD) sprayed ultralow-volume (ULV) formulations of pyrethrin insecticide (Evergreen EC 60-6: 6% pyrethrin insecticide, 60% piperonyl butoxide; MGK, Minneapolis, MN, applied as 0.003 kg/ha [0.0025 lb/acre]) over 218 km² in north Sacramento and 243.5 km² in south Sacramento on three consecutive evenings in August 2005. We evaluated the impact of this intervention in north Sacramento on the abundance and WNV infection rates of Culex pipiens L. and Culex tarsalis Coquillett. Mortality rates of caged Cx. tarsalis sentinels ranged from 0% under dense canopy to 100% in open fields. A comparison of weekly geometric mean mosquito abundance in CO₂-baited traps in sprayed and unsprayed areas before and after treatment indicated a 75.0 and 48.7% reduction in the abundance of Cx. pipiens and Cx. tarsalis, respectively. This reduction was statistically significant for Cx. pipiens, the primary vector of WNV, with highest abundance in this urban area, but not for Cx. tarsalis, which is more associated with rural areas. The infection rates of WNV in Cx. pipiens and Cx. tarsalis collected from the spray zone were 8.2 and 4.3 per 1,000 female mosquitoes in the 2 wk before and the 2 wk after applications of insecticide, respectively. In comparison, WNV infection rates in Cx. pipiens and Cx. tarsalis collected at same time interval in the unsprayed zone were 2.0 and 8.7 per 1,000, respectively. Based on the reduction in vector abundance and its effects on number of infective bites received by human population, we concluded that the aerial application of pyrethrin insecticide reduced the transmission intensity of WNV and decreased the risk of human infection.

Larval and pupal surveys of 439 natural and 2,455 domestic containers (total of 2,894 containers) were undertaken in four villages in American Samoa during the wet and dry seasons. For the first time, larvae and pupae of Ae. oceanicus were found in a variety of domestic containers (including buckets, plastic and polystyrene containers, cans, and tires) in addition to their traditionally reported habitats of plant leaf axils. Finding Ae. oceanicus in artificial containers in three villages during both the wet and dry seasons suggests that Ae. oceanicus is adapting to use these increasingly abundant water sources for breeding sites. The larger water volumes held by such containers could ensure the survival of this species during prolonged dry weather periods.

Granulocytic anaplasmosis (GA), caused by Anaplasma phagocytophilum, is a potentially fatal, emerging rickettsial disease of humans, domestic animals, and wildlife. The purpose of this study was to determine whether sciurids from multiple areas of northern California were infested with ticks or exposed to or infected with A. phagocytophilum using polymerase chain reaction (PCR) and indirect-fluorescent antibody (IFA) serology. Sciurids of nine different tree- and ground-dwelling species were assessed: arboreal squirrels (western and eastern gray squirrels, Sciurus griseus and S. carolinensis, and Douglas squirrels, Tamiasciurus douglasii) but not northern flying squirrels (Glaucomys sabrinus) had greater evidence of exposure and current infection than did semiarboreal or ground dwelling sciurids (California ground squirrels, Spermophilus beecheyi, and chipmunks, Tamias spp.). Western gray squirrels had the most extensive exposure (70.7% seroprevalence and 12.1% PCR prevalence). Positive squirrels were identified in all regions where squirrels were collected. A logistic regression identified being a western gray squirrel (OR = 20.5, P = 2.95 × 10⁻⁸) and from the north coastal region of California (OR = 9.052, P = 1.41 × 10⁻⁶) as having the highest risk of exposure to A. phagocytophilum. Five of nine sciurid species had evidence of infestation with Ixodes pacificus or I. spinipalpis that could vector A. phagocytophilum. Extensive exposure from multiple areas suggests sciurids may be important in the maintenance of GA in California and indicates that studies of reservoir competence of these species are warranted.

During field work in Nazaré Paulista, state of São Paulo, Brazil, we found 13 (56.5%) of 23 birds (mostly Passeriformes) to be infested by 28 larvae and 1 nymph of Amblyomma spp. Two larvae were reared to the adult stage, being taxonomically identified as Amblyomma parkeri Fonseca and Aragão, whereas five larvae and one nymph were identified as Amblyomma longirostre Koch. All six A. longirostre specimens were shown to be infected by rickettsia, as demonstrated by polymerase chain reaction (PCR) targeting two rickettsial genes (gltA and ompA) or isolation of rickettsia in cell culture from one of the ticks. This isolate was designated as strain AL, which was established in Vero cell culture and was molecularly characterized by DNA sequencing fragments of the rickettsial genes gltA, htrA, ompA, and ompB. Phylogenetic analyses inferred from ompA and ompB partial sequences showed a high degree of similarity of strain AL with Rickettsia sp. strain ARANHA, previously detected by PCR in A. longirostre ticks from Rondônia, northern Brazil. We conclude that strain AL is a new rickettsia genotype belonging to the same species of strain ARANHA, which are closely related to Candidatus ’R. amblyommii’. Further studies should elucidate if strains AL and ARANHA are different strains of Candidatus ’R. amblyommii’ or are a new species.

Mosquito population dynamics have been monitored on an annual basis in the state of Iowa since 1969. The primary goal of this project was to integrate light trap data from these efforts into a centralized back-end database and interactive website that is available through the internet at http://iowa-mosquito.ent.iastate.edu. For comparative purposes, all data were categorized according to the week of the year and normalized according to the number of traps running. Users can readily view current, weekly mosquito abundance compared with data from previous years. Additional interactive capabilities facilitate analyses of the data based on mosquito species, distribution, or a time frame of interest. All data can be viewed in graphical and tabular format and can be downloaded to a comma separated value (CSV) file for import into a spreadsheet or more specialized statistical software package. Having this long-term dataset in a centralized database/website is useful for informing mosquito and mosquito-borne disease control and for exploring the ecology of the species represented therein. In addition to mosquito population dynamics, this database is available as a standardized platform that could be modified and applied to a multitude of projects that involve repeated collection of observational data. The development and implementation of this tool provides capacity for the user to mine data from standard spreadsheets into a relational database and then view and query the data in an interactive website.

Chrysomya megacephala and Chrysomya rufifacies are two predominant necrophagous species in Taiwan. Larvae of the latter can prey on other maggots, including that of their own species as facultative food. This facultative characteristic of C. rufifacies may enhance its competitive advantage over other maggots and could also change the situation of other coexisting colonies. In this study, these two species were colonized in the laboratory, and the main objective was to try to understand the effect of competition on larval development. According to our results, intraspecific competition mostly occurred as competition for food; when the rearing density was increased, larvae pupated earlier, resulting in a lighter adult dry weight. The tendencies were similar in both species, but C. megacephala developed smaller viable adults and had higher survivorship at high densities. Although C. rufifacies could use the food resource of cannibalism, its survivorship was still low. Our results also showed there were significant interactions between intraspecific competition and the density factor. However, with interspecific competition, the first-instar larvae of C. rufifacies invaded maggot masses of C. megacephala to feed together. The third instars of C. rufifacies were able to expel C. megacephala larvae from food by using a fleshy protrusion on their body surface; C. megacephala was usually forced to pupate earlier by shortening its larval stages. The results indicated that a temporary competitive advantage could only be obtained by C. rufifacies under a proper larval density. In addition, the effects on different larval stages, the responses to different competition intensities, and the temperature-dependent effects on interspecific competition are also discussed. In general, under mixed-species rearing at different temperatures and densities, larval duration, adult dry weight, and survivorship of both species decreased. However, our results did not completely agree with previous studies, and we suspect that the difference was partially caused by different experimental designs and different biological characters of different blow fly colonies. Our results also suggest that both the predation ability and defense or escape activity should be taken into account when evaluating larval competitive advantages. The durations of larval stages of these two species could be decreased by ≈54 h when a single species was reared alone and food was limited; the largest reduction in larval duration, ≈25 h in C. megacephala and 34 h in C. rufifacies, caused by interspecific competition was under a high larval density. In conclusion, competition decreased the larval duration of these two species by up to 2 d; this also draws attention to justifying the postmortem interval estimation of using larval developmental data when larval competition exists.

We exploited elevation gradients (1,500–2,400 m) ranging from plains to montane areas along the Poudre River and Big Thompson River in the northern Colorado Front Range to determine how mosquito species richness, composition, and abundance change along natural habitat-climate-elevation gradients. Mosquito collections in 26 sites in 2006 by using CO₂-baited CDC light traps yielded a total of 7,136 identifiable mosquitoes of 27 species. Commonly collected species included Aedes vexans (Meigen) (n = 4,722), Culex tarsalis Coquillett (n = 825), Ochlerotatus increpitus (Dyar) (n = 546), Ochlerotatus trivittatus (Coquillett) (n = 303), Aedes cinereus Meigen (n = 280), Ochlerotatus melanimon (Dyar) (n = 146), Ochlerotatus dorsalis (Meigen) (n = 67), Culiseta inornata (Williston) (n = 52), Ochlerotatus pullatus (Coquillett) (n = 38), Ochlerotatus spencerii idahoensis (Theobald) (n = 37), and Culex pipiens L. (n = 29). Species richness was highest in plains habitats at elevations below 1,600 m. Numerous species were found exclusively or predominantly at low elevations below 1,700 m [Anopheles earlei Vargas, Anopheles freeborni Aitken, Coquilletidia perturbans (Walker), Culex erythrothorax (Dyar), Cx. pipiens, Culex territans Walker, Oc. dorsalis, Ochlerotatus hendersoni (Cockerell), Oc. melanimon, and Oc. trivittatus], whereas others occurred predominantly at high elevations above 2,300 m [Ae. cinereus, Culiseta incidens (Thomson), Culiseta morsitans (Theoblad), Ochlerotatus cataphylla (Dyar), Ochlerotatus intrudens (Dyar), Oc. pullatus, and Ochlerotatus punctor (Kirby)]. Ae. vexans and Cx. tarsalis were abundant in the plains (<1,600 m; mean June–August temperature >19.5°C), occurred at low abundances in foothills and low montane areas (1,610–1,730 m; 18.0–19.5°C), and they were collected only sporadically in montane areas above 1,750 m (mean June–August temperature <17.5°C). These findings suggest that future climate warming may lead to shifts in distribution patterns of West Nile virus vectors (e.g., Cx. tarsalis) toward higher elevations in Colorado.

The appearance of phenotypic (and probably genetic) exoskeleton anomalies in Ixodes ticks, first discovered and described elsewhere, seems to be a global phenomenon clearly related to environment pollution by heavy metal ions. These external markers of cadmium accumulation in the tick indicate an enhanced risk of tick-borne infection related to an increased vectorial capacity. This manifests itself in the ability of infected ticks both to quest longer and to show increased locomotory activity (hunting) compared with normal ticks. Ticks with exoskeleton anomalies show a greater susceptibility to different microorganisms, including tick-borne pathogens, and more intense pathogen replication with a higher prevalence of multi-infection.