Lutzomyia (Nyssomyia) intermedia (Lutz & Neiva 1912) and Lutzomyia (Nyssomyia) whitmani (Antunes & Coutinho 1939) (Diptera: Psychodidae) are vectors of American cutaneous leishmaniasis in several endemic regions of Brazil. We analyzed the external morphological aspects of the immature stages of these two vectors by using scanning electron microscopy. In general, the larval stages of the two species are morphologically similar, although some differences were noted. Detailed examination of the eggs of both species revealed similar exchorionic ornamentations of unconnected parallel ridges. The larval head capsules are well defined, heavily sclerotized, and bear prominent chewing mouthparts. The abdominal segments are easily recognized by the presence of prolegs on their ventral surfaces. The morphology of the anal lobe on the terminal abdominal segment differs between the two species. We found the following three types of sensillae inserted on the antennae: 1) clavate basiconic; 2) small, blunt coeloconic; and 3) multipourous clavate coleoconic. In addition; five subtypes of trichoid sensillae were found on the larval body: 1) long, 2) short, 3) curved long, 4) brush-like, and 5) weakly brush-like. The caudal filaments located on the last abdominal segment were recognized as long trichoid sensillae. We observed pores on the surface of the clavate coelonic sensillae and on the caudal filaments that presumably function as chemoreceptors. The larvae of the two species show similarities in the lobular-form antennae of L1 larvae, which changes to digitiform in second instar (L2), L3, and L4. This study demonstrated that the external surface of the eggs and larvae of Lu. intermedia and Lu. whitmani are morphologically similar, but they can be distinguished by details in the microanatomy observed by scanning electron microscopy.

Larvae of the four fleas infesting nests of the southern flying squirrel, Glaucomys volans volans (L.) [Conorhinopsylla stanfordi Stewart, Epitedia faceta (Rothschild), Opisodasys pseudarctomys (Baker), and Orchopeas howardi (Baker)], and of the bat fleas Myodopsylla insignis (Rothschild) and Sternopsylla distincta texana (C. Fox), associated with the bats Myotis lucifugus (Le Conte) and Tadarida brasiliensis (I. Geof. St. Hilaire), respectively, are described. C. stanfordi has the second posterior-row seta on abdominal segments 1–5 at most one fourth the length of the first and third setae, but it is unique among the Leptopsyllini with five short setae in abdominal segment 9 anterior row. E. faceta has the straight line of anterior-row setae 2–5 on abdominal segment 1, which is diagnostic for Phalacropsyllini. O. howardi and O. pseudarctomys have three anterior-row setae on the anal comb, three ventrolatera1 setae on the anal segment (abdominal segment 10), and a narrow mandible with five or more teeth as other Ceratopyl1inae, but O. pseudarctomys is distinguishable from O. howardi because the first setae on the posterior row of the head is long (greater than one half the length of the third posterior-row setae), the ventral setae on abdominal segment 7 are different sizes, and the third anterior-row setae on abdominal segment 8 does not extend past the spiracle posterior to it. Bat flea larvae have six posterior-row setae on abdominal segments 1–9 with the anal comb anterior row with two or more setae; M. insignis has eight mandible teeth and S. distincta texana three to four.

Mark-release-recapture (MRR) experiments were conducted with emerging Anopheles gambiae s.l. and Anopheles funestus Giles at Jaribuni and Mtepeni in Kilifi, along the Kenyan Coast. Of 739 and 1,246 Anopheles released at Jaribuni and Mtepeni, 24.6 and 4.33% were recaptured, respectively. The daily survival probability was 0.96 for An. funestus and 0.95 for An. gambiae in Jaribuni and 0.83 and 0.95, respectively, in Mtepeni. The maximum flight distance recorded was 661 m. The high survival probability of An. gambiae and An. funestus estimated accounts for the continuous transmission of malaria along the Kenyan coast. This study also shows that the release of young, emergent female Anopheles improves the recapture rates and may be a better approach to MRR studies.

The ability of a simple sweeping method, coupled to calibration factors, to accurately estimate the total numbers of Aedes aegypti (L.) (Diptera: Culicidae) pupae in water-storage containers (20–6,412-liter capacities at different water levels) throughout their main dengue virus transmission temperature range was evaluated. Using this method, one set of three calibration factors were derived that could accurately estimate the total Ae. aegypti pupae in their principal breeding sites, large water-storage containers, found throughout the world. No significant differences were obtained using the method at different altitudes (14–1,630 m above sea level) that included the range of temperatures (20–30°C) at which dengue virus transmission occurs in the world. In addition, no significant differences were found in the results obtained between and within the 10 different teams that applied this method; therefore, this method was extremely robust. One person could estimate the Ae. aegypti pupae in each of the large water-storage containers in only 5 min by using this method, compared with two people requiring between 45 and 90 min to collect and count the total pupae population in each of them. Because the method was both rapid to perform and did not disturb the sediment layers in these domestic water-storage containers, it was more acceptable by the residents, and, therefore, ideally suited for routine surveillance purposes and to assess the efficacy of Ae. aegypti control programs in dengue virus-endemic areas throughout the world.

For the development of community-based vector control programs for dengue prevention, one of the key components is to formulate an adequate classification scheme for the different containers in which immature Aedes mosquitoes develop. Such a standardized scheme would permit more efficient targeting of efforts and resources in the most productive way possible. Based on field data from Kamphaeng Phet, Thailand, we developed a classification method that consists of the shape (S), use (U), and material (M) of the container (SUM-method). We determined that by targeting the four container classes that held the most Ae. aegypti pupae, adult mosquito production could theoretically be reduced by 70%. The classification method may be equally suitable for similar studies elsewhere in the world. Main advantages of the classification scheme are that categorization of containers does not need to be done a priori, that there is no “miscellaneous” class, and that different immature control strategies can be easily and prospectively tested with a local database. We expect that the classification strategy will 1) facilitate comparison of results among different ecological and geographic settings and 2) simplify communication among vector control personnel and affected communities.

Ochlerotatus (Finlaya) japonicus japonicus (Theobald; =Aedes japonicus; see Reinert 2000) (Diptera: Culicidae), is an introduced Asian mosquito species first detected in the northeastern United States in 1998. Since its initial discovery, this species has spread to many neighboring states and Canada. It was first identified in North Carolina, South Carolina, and Georgia in 2003. Larval surveys were conducted during 2005 and 2006 in the Southern Appalachians, USA, on a variety of natural and artificial containers to determine extent of Oc. japonicus establishment and larval habitat requirements. Detritus amounts were measured in each container habitat, and co-occurring larval mosquito species were examined as indicators of potential interspecific competition. Data reveal that Oc. japonicus was the most abundant container-inhabiting mosquito species in this survey. It exhibits flexibility in its use of container oviposition habitats, it can persist in a wide range of conditions, and it co-occurs with a wide range of larval mosquito species. Its rapid and successful establishment warrants continued monitoring, because its potential role as a nuisance species or arbovirus vector remains unknown.

We performed the first quantitative survey of ectoparasitic assemblages on three species of mormoopid bats living on the Caribbean island of Puerto Rico: Mormoops blainvillii Leach (n = 40), Pteronotus quadridens Gundlach (n = 40), and Pteronotus parnellii Gray (n = 9). We examined bats for parasites primarily on 8–10 May and 24–27 July 2002 at Culebrones Cave, near Arecibo, Puerto Rico. Only 50% of M. blainvillii were infested with at least one parasite, compared with 85–100% for Pteronotus; infested individuals of both species of Pteronotus also harbored a greater number of parasites than did M. blainvillii. The assemblage on M. blainvillii was less diverse than in the other species and more dominated by a single group of parasites, the chiggers. Chirodiscid ear mites and spinturnicid wing mites were common on both species of Pteronotus but absent from M. blainvillii. All P. parnellii harbored streblid flies, but none typically was found on P. quadridens or M. blainvillii. Adult female M. blainvillii and P. quadridens sheltered a greater number of ectoparasites than did males. All host–parasite combinations represented new associations for Puerto Rico.

Culicoides sonorensis (Wirth & Jones) (Diptera: Ceratopogonidae) adults were active from May through October during 2002–2006 in southern Alberta, Canada. Adults were first captured in May, and populations peaked in early June, late July, and late August. The first population peak occurred when mean weekly temperatures exceeded 16°C, resulting in a variable amount of time for spring emergence. This asynchrony in spring emergence accounted for much of the annual variation in timing of subsequent population peaks. Peaks were separated by an average of 6–7 wk. C. sonorensis seems to have one overwintering generation and two generations during the summer. Abundance was correlated among sites located up to 90 km apart. Abundance at a rangeland site increased more rapidly with mean weekly temperatures than at feedlot sites. The proportion female ranged from 0.68 to 0.83 but showed no consistent differences between rangeland and feedlot sites. The proportion female declined with distance from a developmental area at the rangeland site. Proportion parous was similar among rangeland and feedlot sites, and it also declined with distance from a developmental area at the rangeland site. The proportion parous increased early in the season, fluctuated throughout the mid-season, and increased with cooler temperatures in the fall. The proportion parous tended to increase when temperatures decreased. Estimates of adult daily survival were generally >0.8. Survival declined with temperature, was lowest in midsummer, and increased during the fall.

Chemical cues play an important role in the host-seeking behavior of blood-feeding mosquitoes (Diptera: Culicidae). A field study was carried out in The Gambia to investigate the effects of human odor or synthetic odor blends on the attraction of mosquitoes. MM-X traps baited with 16 odor blends to which carbon dioxide (CO₂) was added were tested in four sets of experiments. In a second series of experiments, MM-X traps with 14 odor blends without CO₂ were tested. A blend of ammonia and L-lactic acid with or without CO₂ was used as control odor in series 1 and 2, respectively. Centers for Disease Control and Prevention (CDC) traps were placed in a traditional house and an experimental house to monitor mosquito densities during the experiments. The MM-X traps caught a total number of 196,756 mosquitoes, with the most abundant species belonging to the genera Mansonia (70.6%), Anopheles (17.5%), and Culex (11.5%). The most abundant mosquito species caught by the CDC traps (56,290 in total) belonged to the genera Mansonia (59.4%), Anopheles (16.0% An. gambiae s.l. Giles, and 11.3% An. ziemanni Grünberg), and Culex (11.6%). MM-X traps baited with synthetic blends were in many cases more attractive than MM-X traps baited with human odors. Addition of CO₂ to synthetic odors substantially increased the catch of all mosquito species in the MM-X traps. A blend of ammonia L-lactic acid CO₂ 3-methylbutanoic acid was the most attractive odor for most mosquito species. The candidate odor blend shows the potential to enhance trap collections so that traps will provide better surveillance and possible control.

Aedes albopictus (Skuse) (Diptera: Culicidae) invaded the United States in 1985 and spread rapidly across eastern North America, whereas Aedes japonicus (Theobald) invaded and became established in the United States more recently (1998). The two species may co-occur in container habitats, and they are of potential public health concern as arbovirus vectors. To evaluate ecological differences between Ae. albopictus and Ae. japonicus, we compared larval foraging behavior of these two species. Based on results from a previous competition experiment, we predicted that Ae. albopictus would be a more active forager than Ae. japonicus. However, Ae. japonicus exhibited greater foraging activity than Ae. albopictus in four of six food environments, including a “no food” control treatment. Our results, therefore, suggest that more active foraging does not connote superior competitive ability, and competitive interactions between these species may be mediated by factors other than feeding behavior.

An entomological survey was carried out in three humid savannah sites of western Burkina Faso (Bama, Lena, and Soumousso) to 1) update the taxonomy of the Anopheles funestus Giles group, 2) examine the role of each species in malaria transmission, 3) characterize the insecticide resistance status of this malaria vector, and 4) determine the distribution of An. funestus chromosomal forms in these areas. Polymerase chain reaction identification of the members showed the occurrence of An. leesoni Evans in Lena and An. rivulorum-like in Soumousso in addition to An. funestus s.s. Malaria transmission was ensured mainly by An. funestus s.s. both in Soumousso and Lena and by An. gambiae s.s. Giles in Bama, the rice-growing area. The insecticide resistance status performed only on An. funestus indicated that this mosquito was susceptible to pyrethroids irrespective of the study area, but it was resistant to dieldrin. Furthermore, the occurrence of the two chromosomal forms of An. funestus, namely, Kiribina and Folonzo, seemed to follow ecological setups where Kiribina predominated in the irrigated area and Folonzo was more frequent in classic savannah. This study revealed that the problematic of An. funestus taxonomy was closer to that of An. gambiae requiring more structured studies to understand its genetic ecology.

The blood-feeding cosmopolitan stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), is thought to disperse rapidly and widely, and earlier studies of allozyme variation were consistent with high vagility in this species. The geographic origins of New World populations are unknown. Diversity at mitochondrial loci r16S and cytochrome oxidase I was examined in 277 stable flies from 11 countries, including five zoogeographical regions. Of 809 nucleotides, 174 were polymorphic and 133 were parsimony informative. Seventy-six haplotypes were found in frequencies consistent with the Wright–Fisher infinite allele model. None were shared among four or more zoogeographical regions. The null hypothesis of mutation neutrality was not rejected, thereby validating the observed distribution. Fifty-nine haplotypes were singular, eight were private and confined to the Old World, and three of 76 haplotypes were shared between the Old and New World. Only 19 haplotypes were found in the New World, 14 of which were singletons. Haplotype and nucleotide diversities were heterogeneous among countries and regions. The most diversity was observed in sub-Saharan Africa. Regional differentiation indices were G_RT = 0.26 and N_RT = 0.31, indicating populations were highly structured macrogeographically. Palearctic and New World flies were the least differentiated from each other. There were strong genetic similarities among populations in the Nearctic, Neotropical, and Palearctic regions, and it is most likely that New World populations were derived from the Palearctic after 1492 CE, in the colonial era.

The human body louse, Pediculus humanus humanus L. (Anoplura: Pediculidae), is a vector of several diseases, including louse-borne epidemic typhus, relapsing fever, and trench fever, whereas the head louse, Pediculus humanus capitis De Geer (Anoplura: Pediculidae), is more a pest of social concern. Sequencing of the body louse genome has recently been proposed and undertaken by National Human Genome Research Institute. One of the first steps in understanding an organism’s genome is to determine its genome size. Here, using flow cytometry determinations, we present evidence that body louse genome size is 104.7 ± 1.4 Mb for females and 108.3 ± 1.1 Mb for males. Our results suggest that head lice also have a small genome size, of similar size to the body louse. Thus, Pediculus lice have one of the smallest genome sizes known in insects, suggesting it may be a suitable choice as a minimal hemimetabolous genome.

Mutations were identified in the cDNA sequence encoding the acetylcholinesterase BmAChE3 in strains of Rhipicephalus (Boophilus) microplus (Canestrini) resistant or susceptible to organophosphate (OP) acaricide. The mutation that occurred most frequently in the OP-resistant San Román strain resulted in a substitution of glutamine (Q) for arginine (R) at position 86 in BmAChE3 (position 66 in mature BmAChE). Clones containing the mutant and wild-type cDNA sequences were expressed in the baculovirus system. Enzyme kinetics of recombinant BmAChE3 containing or lacking the R86Q mutation demonstrated that the R86Q mutation increased substrate affinity and conferred insensitivity to paraoxon inhibition. This is the first demonstration of a mutation in a gene encoding an ixodid acetylcholinesterase resulting in OP insensitivity. A restriction fragment length polymorphism assay was developed and used to diagnose the frequency of the R86Q mutation in BmAChE3 genomic DNA from seven laboratory-colonized strains. Use of the R86Q diagnostic assay detected an increased frequency of the R86Q mutation in OP-resistant tick strains compared with that of OP-susceptible strains; however, the R86Q mutation was also present in OP-susceptible strains at unexpectedly high frequency. Because the R86Q mutation generates an OP-resistant enzyme in vitro and it is present at an elevated frequency in laboratory strains selected for OP resistance, we conclude that the data are consistent with a potential role for BmAChE3 in development of OP resistance; however, because the R86Q mutation has a high frequency in susceptible strains, the R86Q mutation alone is insufficient to generate the OP-resistant phenotype at the organismal level. There are likely to be additional mutations in BmAChE3, mutations in additional acetylcholinesterase genes, or additional resistance mechanisms (e.g., oxidative metabolism) that contribute to expression of the OP-resistant phenotype.

In southern Europe, orbiviral diseases such as bluetongue (BT) have been assumed to have been largely transmitted by the classical Afro-Asian vector Culicoides imicola Kieffer (Diptera: Ceratopogonidae). Recent outbreaks have occurred in regions where C. imicola is normally absent, supporting the theory that other species belonging to the Obsoletus or Pulicaris complexes may play a role in BT virus transmission. Investigations of the ecology of the species within the former group are hampered by females of member species being extremely difficult to separate by classical morphology. To allow straightforward separation of these species in France, a multiplex polymerase chain reaction-based on internal transcribed spacer (ITS)-1 rDNA was developed to distinguish between Culicoides chiopterus Meigen, Culicoides dewulfi Goetghebuer, Culicoides montanus Shakirjanova, Culicoides obsoletus Meigen, and Culicoides scoticus Downes & Kettle. This tool will be useful in defining both the vector role and larval biotopes of these species in Europe.

Studies were done in Manitoba, Canada, to evaluate the impact of exercise on repellent performance against mosquitoes. Two products containing the active ingredient N,N-diethyl-3-methylbenzamide (deet) were tested; one product was a polymer-based cream (3M Ultrathon Insect Repellent) and the other product was an alcohol-based pump spray formulation (Muskol Insect Repellent). Assessments were done in the laboratory using Aedes aegypti (L.) and in the field with naturally occurring populations of mosquitoes. Repellent was applied to the forearms (laboratory) or a lower leg (field) of test subjects at 1.5 g of test product per 600 cm² surface area (0.75 or 0.83 mg deet/cm²). For a given test day, subjects exercised or did not. Exposure to mosquito attack was for 1 min at 30-min intervals in laboratory procedures, and it was continuous in field tests. Performance was measured as complete protection time (CPT). Moderate levels of physical activity resulted in a >40% decline in mean CPT, from 468 to 267 min in the laboratory experiments and from 359 to 203 min in field tests. Repellent product did not affect the magnitude of the decline. Mean biting pressure during field trials was 21.3 bites per min, and mosquito collections were made up primarily of Ochlerotatus sticticus (Meigen) and Aedes vexans (Meigen).

Behavioral responses of two wild-caught populations of Anopheles minimus complex, species A and C, exposed to operational field doses of three commonly used agricultural insecticides, carbaryl (carbamate), malathion (organophosphate) and cypermethrin (pyrethroid), were characterized using an excito-repellency test system. Test populations were collected from different localities in Kanchanaburi Province, western Thailand. Both populations showed strong irritancy by quickly escaping test chambers after direct contact with individual surfaces treated with each insecticide compared with match-paired untreated controls. Noncontact repellency response to cypermethrin and carbaryl was significantly pronounced in both A and C populations, but comparatively weak when exposed to malathion. Noncontact repellency produced much weaker escape response in both populations, but in some species–chemical combinations, it remained significant compared with controls. We conclude that contact irritancy is a major behavioral response of both A and C when exposed directly to any of the three compounds, whereas only cypermethrin produced a significant repellency response in species A.

Infection of Aedes aegypti (L.) (Diptera: Culicidae) with Edhazardia aedis (Microsporidia: Culicosporidae) reduced mean human host attraction and landing/probing rates in female mosquitoes by 53 and 62%, respectively, compared with rates in microsporidia-free females. Infection with E. aedis reduced the average weight of unfed female mosquitoes by 4%, caused them to imbibe 23% less blood, and to lay 30% fewer eggs than healthy females. In contrast, E. aedis-infected mosquitoes required 20% more time (>1 h) than healthy females to bite skin treated with 15% DEET. Statistically significant morbidity in E. aedis-infected females was indicated by reductions in host attraction and landing/probing responses, the mass of unfed and blood-engorged females, and fecundity, and by increased DEET repellency.

Toxicities of three chitin synthesis inhibitors (diflubenzuron, nikkomycin Z and polyoxin D) were evaluated using second instars of the common malaria mosquito, Anopheles quadrimaculatus Say (Diptera: Culicidae). Neither nikkomycin Z nor polyoxin D at 50 μg/liter caused significant larval mortality, although they reduced the body weight of the survivors by 20.5 and 33.8%, respectively, in 48 h. In contrast, exposures of the larvae to diflubenzuron at 12.5 μg/liter for 48 h resulted in 86.7% larval mortality and reduced the body weight of the survivors by 29.1%. Exposure of the pupae (<12 h old) to diflubenzuron at 100 μg/liter for 48 h caused 18.9% pupal mortality and consequently reduced the adult emergence by 24.7% from the surviving pupae. Furthermore, exposure of third instars to diflubenzuron at 4, 20, 100, and 500 μg/liter for 24 h resulted in the reduction of larval chitin contents by 4.25, 33.2, 35.2, and 57.7%, respectively. Such an effect seemed to be associated with only cuticular chitin synthesis because the same exposures did not significantly affect chitin contents in the guts. Our results indicated that diflubenzuron was highly toxic to second instars by not only causing high larval mortality but also by affecting their growth. Diflubenzuron was also fairly toxic to pupae by not only causing pupal mortality but also affecting the adult emergence. Our results suggest that diflubenzuron might affect only chitin synthesis in the cuticle but not in the peritrophic matrix, which is probably due to diflubenzuron’s direct contact to mosquito larvae in water, slow distribution in insect body, rapid degradation in the insect gut, or a combination.

The clinical signs of a Sarcoptes scabiei (De Geer) (Acari: Sarcoptidae) infestation are initially delayed, which suggests that the mites can depress the immune/inflammatory response. The purpose of this study was to investigate the modulatory properties of scabies mites in vivo at the gene expression level in a secondary lymphoid organ that is involved in initiating an immune response to the parasite. We found that substances from scabies mites influenced the expression of mRNA for molecules that participate in the sequestering of lymphocytes in the periarteriolar lymphoid sheath, primary follicle, and marginal zone of the spleen. Mice exposed to live scabies mites exhibited decreased mRNA expression for the adhesion molecules intercellular adhesion molecule (ICAM)-1, ICAM-2 and L-selectin; the cytokines tumor necrosis factor (TNF)α and CCL5; and the receptors for several other cytokines including TNF and interferon γ. In addition, exposure to live mites or vaccination with a scabies extract resulted in reduced expression of mRNA for B7-2, CD40, CD4, CD8, and CD45, thereby potentially reducing the physical interactions between B cells and T-helper (Th)2 helper cells, between Th1 and Tc cells, and between T-helper cells and antigen-presenting cells, thus depressing their function in response to thymus-dependent antigen. Live scabies mites also depressed expression of toll-like receptors 2, 4, and 6. In conclusion, our results indicate that live mites produce substances that can down-regulate expression of adhesion molecules, cytokines, chemokines, chemokine receptors, and lymphocyte surface molecules involved in leukocyte sequestering and the interaction of B and T cells during activation of an immune response in the spleen.

To identify the natural vectors of Dirofilaria repens Railliet et Henry, entomological samplings were carried out in four sites within the Lazio region, foci of canine subcutaneous dirofilariasis. Collections were made in 2002–2003 by means of dog-baited and miniature Centers for Disease Control and Prevention traps as well as on humans. Microscopy identified 1,576 attracted mosquito females as belonging to six species, but molecular diagnostics detected filarial DNA only in Culex pipiens L. and Aedes albopictus (Skuse, 1894). Dirofilaria immitis Leidy DNA, D. repens DNA, or both were found in the head and thorax of both mosquitoes. The simultaneous presence of vectors showing diurnal and nocturnal activity patterns is of concern for animal and human health. The finding of D. immitis DNA in mosquitoes in areas where only D. repens was been recovered in dogs also demonstrates that this filarial parasite circulates among carnivores (wild or domesticated pets).

A comparative study of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) infection rates in Culex mosquitoes collected at 13 sites, seven reporting WNV-positive dead corvids (case sites) and six without reported dead birds (control sites) was conducted in Davis, CA, from 14 to 21 July at the beginning of the 2006 WNV outbreak. In total, 3,051 Culex mosquitoes were collected using gravid traps and CO₂-baited traps; WNV-infected mosquitoes were only collected with CO₂-baited traps. WNV-infected Culex pipiens L. were collected at one of the seven case sites. Six of seven case sites yielded WNV-infected Culex tarsalis Coquillett, whereas only one of six control sites had WNV-infected Cx. tarsalis. Overall, the odds of finding WNV-positive mosquitoes were 19.75 times greater at sites reporting a WNV-infected dead corvid than sites without a WNV-infected dead corvid. Maximum likelihood estimates of the overall infection rates at the case sites were 3.48/1,000 for Cx. tarsalis and 8.69/1,000 for Cx. pipiens compared with 1.02/1,000 in Cx. tarsalis collected at the control sites. Results indicate that Cx. tarsalis was important in early season enzootic transmission within Davis and that sites reporting WNV-infected dead corvids are areas to focus control and surveillance efforts.

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) persistently infects many mosquito tissues, and it has been associated with cytopathological changes in midgut muscles and salivary glands. However, the effects of WNV infection on mosquito fitness (survival and reproduction) are not known. We conducted a life table study of individually housed female Culex tarsalis Coquillett. After an initial bloodmeal from a WNV-infected or uninfected chicken, mosquitoes were provided sucrose and offered weekly opportunities to feed on a hanging blood drop. WNV transmission status was determined by testing the remaining blood drop for virus after mosquito feeding. Dead mosquitoes and eggs were collected daily. Mosquito legs and bodies were tested for WNV, and eggs were counted and allowed to hatch. Two replicates of this experiment were performed, with a total of 62 mosquitoes that fed on a WNV-infected chicken (of which 21 became infected) and 43 mosquitoes that fed on an uninfected chicken. Fecundity of WNV-infected mosquitoes was significantly lower than that of uninfected mosquitoes, especially during the first oviposition. WNV infection was associated with smaller egg rafts, whereas increasing wing length and WNV titer in the legs had a positive effect on egg raft size. Additionally, infected mosquitoes had lower egg hatch rates than did uninfected mosquitoes. There were no significant differences in survival between infected and uninfected mosquitoes. Blood feeding rates were higher in infected mosquitoes than in uninfected mosquitoes. A small amount of virus (average, 378; range, 5–5,000 plaque-forming units) was transmitted to the blood drops fed upon by infected mosquitoes. Although WNV infection negatively impacts mosquito reproduction, facets of mosquito biology that are critical to virus transmission success were either not affected (survival) or changed in such a way as to result in enhanced vectorial capacity (blood feeding).

Anopheles sinensis Wiedemann (63.3%) was the most abundant Anopheles mosquito captured at cowshed resting collections in malaria high-risk areas (northern Gyeonggi Province) near the demilitarized zone (DMZ) in Korea during 2005, followed by Anopheles kleini Rueda (24.7%) and Anopheles pullus M. Yamada (8.7%). At cowshed resting collections in malaria low-risk areas (Jeonnam and Gyeongnam provinces), An. sinensis accounted for 96.8% of all Anopheles spp. collected, followed by An. kleini Rueda (2.7%), whereas no An. pullus were collected. Three species, An. kleini (50.9%), An. pullus (29.0%), and An. sinensis (13.8%), accounted for nearly all of the 224 Anopheles spp. captured by New Jersey light trap near the DMZ. In addition, An. pullus and An. kleini captured by New Jersey light trap near the DMZ and assayed by enzyme linked immunosorbent assay for Plasmodium vivax circumsporozoite antigen concentrations were higher than An. sinensis sensu stricto (s.s.), indicating higher levels of sporozoites. In laboratory studies of four concurrent artificial membrane feedings on malaria-infected blood from patients, F₁ progeny of An. kleini and An. pullus had higher infection rates (8.8 and 7.5%, respectively) than An. sinensis s.s. (4.2%). These data suggest that An. kleini and An. pullus and An. sinensis are vectors of malaria in Korea. Further studies are required to determine the role of these species in the transmission of P. vivax in the Republic of Korea.

Soft ticks are medically important ectoparasites of birds and mammals that are found throughout the world. This report describes isolation and partial characterization of two embryonic cell lines, CCE2 and CCE3, from the seabird soft tick Carios capensis (Neumann). Sequencing of the mitochondrial 16S rRNA gene and karyology confirmed the lines were derived from C. capensis. CCE3 cells were diploid with a modal chromosome number of 20. The population doubling time for cell lines CCE2 and 3 in passage 40 was 6–9 d. A rickettsial endosymbiont, RCCE3, was co-isolated along with line CCE3. Nucleotide sequences of polymerase chain reaction (PCR) products generated using primers specific for rickettsial 17-kDa antigen, outer membrane protein (omp) A, ompB, and citrate synthase genes along with phylogenetic analyses demonstrated that RCCE3 is a previously uncultured endosymbiont. The rickettsia was identified as a symbiont of C. capensis, closely related to rickettsiae previously detected by PCR in C. capensis, Ornithodoros moubata (Murray) and Hemaphysalis sulcata Canestrini & Fanzago, a hard tick. RCCE3 caused a cytopathic effect in C. capensis host cells, and it was transferred to Ixodes scapularis Say cell line ISE6 for maintenance. The rickettsial endosymbiont was eliminated from CCE3 by treatment with oxytetracycline. Cell lines from C. capensis will be useful to researchers investigating interactions between soft ticks and microorganisms, soft tick physiology, and molecular biology. The rickettsia adds to the growing number of Rickettsia species that have been isolated in tick cell culture, and it is available for characterization.

Six species of mosquitoes (Diptera: Culicidae) were collected in sufficient numbers for analysis in segregating traps set at 2-h intervals by using CO₂ and light as attractants in a West Nile virus (family Flaviviridae, genus Flavivirus, WNV) focus in Stratford, CT. The Kolmogorov–Smirnov one-sided test for two samples was used to analyze the data. Mosquito activity began shortly before sunset and continued until shortly after sunrise the next morning. All species had geometric means that were significantly higher during the 2-h period shortly after sunset compared with the 2-h collection before sunset. Species, known to be naturally infected with WNV, were often attracted to these traps in about equal numbers at 2-h intervals during an 8- to 10-h period commencing shortly after sunset. Differences of geometric means were not significant among the four or five 2-h collection periods commencing at sunset for Aedes vexans (Meigen), Culex salinarius Coquillett, and Aedes cinereus Meigen. Aedes cantator (Coquillett) had a significantly higher geometric mean for the 2-h period commencing at sunset, and Coquillettidia perturbans (Walker) was captured in significantly greater numbers during the 2-h period starting at sunset compared with periods commencing 6 h after sunset. Culex pipiens L. tended to have an activity pattern that was primarily nocturnal. Time of night, not meteorological conditions, was the most important factor in determining the nightly variation in the number of trapped mosquitoes. Parity rates of Cx. pipiens collected during specific periods of the night were not significant. In total, 39 isolations of WNV were made from seven species collected primarily during periods of total darkness. Humans are at risk of being bitten by infected mosquitoes throughout the night.

To evaluate the importance of vertebrate species as tick hosts and as reservoir hosts in two endemic areas for Lyme borreliosis in Switzerland, we applied molecular methods for the analysis of bloodmeal source and Borrelia infection in questing Ixodes ricinus L. ticks. In total, 1,326 questing ticks were simultaneously analyzed for Borrelia and for blood meal remnants by using reverse line blot. An overall infection prevalence of 19.0% was recorded for Borrelia sp., with similar rates in both sites. Using a newly developed method for the analysis of bloodmeal targeting the 12S rDNA mitochondrial gene, identification of host DNA from field-collected ticks was possible in 43.6% of cases. Success of host identification at the genus and species level reached 72%. In one site, host identification success reached its maximum in spring (93% in May), decreasing in summer (20% in July) and rising in autumn (73% in October). In the other site, identification rate in ticks remained low from April to July and increased in autumn reaching 68% in October and November. The most prevalent identified host DNA was artiodactyls in both sites. Red squirrel DNA was significantly more frequently detected in ticks collected in one site, whereas insectivore DNA was more frequent in ticks in the other site. DNA from more than one vertebrate host was detected in 19.5% of nymphs and 18.9% of adults. Host DNA was identified in 48.4% of the Borrelia infected ticks. Although DNA from all Borrelia species was found in at least some ticks with DNA from mammals and some ticks with DNA from birds, our results confirm a general association of B. afzelii and B. burgdorferi sensu stricto with rodents, and B. valaisiana and B. garinii with birds.

In 1989, a free-of-charge, statewide tick identification program was initiated in Maine, 1 yr after the first Ixodes scapularis Say (=I. dammini Spielman, Clifford, Piesman & Corwin) ticks were reported in the state. This article summarizes data from 18 continuous years of tick submissions during which >24,000 ticks of 14 species were identified. Data provided include tick stage, degree of engorgement, seasonal abundance, geographical location, host, and age of the person from whom the tick was removed. Maps depict the distributions of the three major species submitted. I. scapularis emerged first along the coast, and then it advanced inland up major river valleys, Dermacentor variabilis Say slowly expanded centrifugally from where it was initially reported in southwestern Maine, and the distribution of long-established Ixodes cookei Packard remained unchanged. Submissions of nymphal I. scapularis closely correlated with reported Lyme diseases cases at the county level. Annual fluctuations of nymphal submissions in Maine correlated with those of Lyme disease cases for New England, supporting the possibility of a regional influence on tick abundance. More ticks were removed from people ≤14 and ≥30 yr of age, and their degree of engorgement was greatest in people ≤20 yr of age and progressively increased in people ≥30 yr of age. This study demonstrates the usefulness and potential of tick identification programs.

In this study, we used ecological niche factor analysis (ENFA) and principal components analysis (PCA) of climate variables to define the climate niches and areas of potential colonization of six species of ticks in the Mediterranean region: Dermacentor marginatus Sulzer, Rhipicephalus bursa Canestrini & Fanzago, Rhipicephalus turanicus Pomerantsev, Matikashvili & Lototsky, Hyalomma marginatum Koch, Hyalomma excavatum Koch, and Boophilus annulatus (Say). ENFA generated distribution models that varied in accuracy from high to very high (area under the curve [AUC] = 0.87–0.97), with the lowest AUC obtained for B. annulatus. PCA provided an adequate separation of the climate niches of different species in the reduced space of the variables. Climate scenarios and factorial consensus analysis were used to evaluate the geographic impact of climate change (as turnover in habitat suitability) on the niches of the ticks and net variations in habitat availability. The scenario that was most compatible with estimates of future climate in the Mediterranean region (increase in temperature and decrease in rainfall) was predicted to produce a sharp increase in the extent of suitable habitat for R. bursa, R. turanicus, and H. marginatum. This scenario would result in a northward expansion of suitable habitat areas for these three species. The highest impact (highest species turnover) would be recorded at the margin of the current distribution range of the three species. A sensitivity analysis of the ecological response of the ticks to the climate change scenarios showed that the response is statistically different in different regions of the PCA-derived niche. These results outline the need to further investigate the potential of bioclimate models to obtain accurate estimations of tick species turnover under conditions of climate change over wide areas.

Landscape and climatic factors regulate distributions of mosquitoes (Diptera: Culicidae) over time and space. The anthropogenic control of mosquito populations is often carried out at a local administrative scale, and it is applied based on the relevant agency’s experiential knowledge rather than systematic analysis of spatial and temporal data. To address this shortcoming, a spatial and temporal analysis of landscape and climatic parameters in relation to mosquito populations in Black Hawk County, IA, USA, has been carried out. Adult mosquito sampling took place using CDC light traps from May to August 2003 in representative landscapes. Mosquitoes were identified to species level with Aedes trivittatus (Coquillet) and Aedes vexans (Meigen) dominating the collection totals. The best publicly available spatial data on landscape and demographic attributes were collated and included land cover, human census, soils, floodplain, elevation, wetlands, hydrography, roads, and vegetation indices derived from satellite imagery. Spatial processing was carried out to organize landscape attributes for statistical comparison with abundance data from the potentially important West Nile virus (family Flaviviridae, genus Flavivirus, WNV) vector species Ae. vexans and Ae. trivittatus. Landscape parameters shown to be significantly correlated with mosquito counts included soil hydrological properties, presence in floodplain, wetland areas, and deciduous and bottomland forest cover. Data on temperature and precipitation were used to investigate the climatic influence on the temporal occurrence of mosquito population abundances. Late spring rain provided ample moisture for mosquito development, but low temperatures delayed widespread emergence of Ae. trivittatus and Ae. vexans until June 2003. Landscape and climatic impacts on adult mosquito population distributions were demonstrated, and these results could form the basis for the development of a spatiotemporal modeling framework that would inform anthropogenic mosquito control and vector-borne disease surveillance. A qualitative discussion concerning Culex pipiens (L.) and Culex restuans Theobald is included.