The human body louse, Pediculus humanus humanus (L.), and the human head louse, Pediculus humanus capitis, belong to the hemimetabolous order Phthiraptera. The body louse is the primary vector that transmits the bacterial agents of louse-borne relapsing fever, trench fever, and epidemic typhus. The genomes of the bacterial causative agents of several of these aforementioned diseases have been sequenced. Thus, determining the body louse genome will enhance studies of host–vector–pathogen interactions. Although not important as a major disease vector, head lice are of major social concern. Resistance to traditional pesticides used to control head and body lice have developed. It is imperative that new molecular targets be discovered for the development of novel compounds to control these insects. No complete genome sequence exists for a hemimetabolous insect species primarily because hemimetabolous insects often have large (2,000 Mb) to very large (up to 16,300 Mb) genomes. Fortuitously, we determined that the human body louse has one of the smallest genome sizes known in insects, suggesting it may be a suitable choice as a minimal hemimetabolous genome in which many genes have been eliminated during its adaptation to human parasitism. Because many louse species infest birds and mammals, the body louse genome-sequencing project will facilitate studies of their comparative genomics. A 6–8× coverage of the body louse genome, plus sequenced expressed sequence tags, should provide the entomological, evolutionary biology, medical, and public health communities with useful genetic information.

The movement of Aedes aegypti (L.) and Aedes albopictus (Skuse) females between sylvatic and urban environments was investigated by marking, releasing, and recapturing adults and by identifying rubidium (Rb)-marked eggs of females that were released after taking a bloodmeal containing RbCl. When released in the forest, Ae. albopictus females flew as far as 1,000 m and reached houses within 1 wk. When Ae. albopictus were released close to houses, most females were recaptured near the release point, and Rb-marked eggs were found 1,000 m away in the forest only once, 35 d after the release. These differing patterns of movement may suggest a preference of Ae. albopictus for the human-modified environment. Ae. aegypti, however, showed low tendency to disperse into the forest. The capacity of Ae. albopictus females to disperse from a sylvatic into a human-modified environment suggests that this species may play a role in the dissemination of forest-restricted pathogens, such as yellow fever virus.

The effectiveness of four types of mosquito traps at sampling Culex mosquitoes was compared at two north central Florida study sites (a commercial dairy and a swine research unit) with highly eutrophic lagoons that have a history of producing large populations of Culex mosquitoes. Traps evaluated included a John Hock (JH) model 1012 CDC style light trap, JH model 1712 CDC Gravid Trap (GT), and American Biophysics Corporation’s Mosquito Magnet-Experimental (MM-X) and commercial model MM-Professional (MM-Pro) traps. The MM-X and MM-Pro traps are based on new counterflow technology. Culex nigripalpus Theobald and Culex quinquefasciatus Say were the two most abundant species collected, and they were the dominant species at the dairy site and swine research unit, respectively. Culex erraticus Dyar & Knabb and Culex salinarius Coquillett also were caught but in much lower numbers than the two dominant species at the swine unit, and rarely at the dairy site. At the dairy site the MM-Pro collection of total female Cx. quinquefasciatus was significantly greater than all other trap types (MM-Pro > GT > MM-X = CDC), and the MM-Pro also caught the most Cx. nigripalpus, but not significantly more than the CDC or MM-X (MM-Pro = CDC = MM-X > GT). At the swine research unit the largest number of female Cx. quinquefasciatus were caught in the MM-X trap, but the only significant difference was with the CDC trap (MM-X = MM-Pro = GT > CDC). For Cx. nigripalpus the CDC trap caught the most females, but these collections were only significantly different from the MM-Pro and GT (CDC = MM-X > MM-Pro > GT). The GT caught significantly more gravid female Cx. quinquefasciatus than all the other trap types at both sites, but collected very few gravid Cx. nigripalpus at either site.

Bacteria were isolated and identified from the digestive tract of the secondary screwworm, Cochliomyia macellaria (F.) (Diptera: Calliphoridae), and their role in the larval development of this insect was assessed in laboratory bioassays. The analysis of 16S rDNA sequences revealed that the bacterial isolates represented four species: Providencia sp., Escherichia coli O157:H7 (Escherich), Enterococcus faecalis (Orla-Jensen), and Ochrobactrum sp. (Holmes). Developmental assays demonstrated that C. macellaria larvae are able to develop on a sterile blood agar, and no bacteria are required to complete larval development. Indeed, developmental times were shorter and survival rates of C. macellaria on a sterile blood agar and the modified Harris rearing diet were greater compared with that on the blood agar inoculated with individual and mixed bacterial isolates. The cultures of Ochrobactrum sp. and E. faecalis supported larval development to a significantly greater extent than those of Providencia sp. and E. coli O157:H7. The presence of bacteria in newly emerged C. macellaria adults also was assessed and revealed that the bacteria in the gut of larvae can survive pupation and colonize the gut of adult flies. This study shows that development of larvae of C. macellaria does not depend on bacteria and that some bacterial isolates negatively impact larval development.

Oviposition traps set in rural to urban environments in three south Florida counties were colonized predominantly by Culex quinquefasciatus Say (35.1%), Aedes albopictus (Skuse) (34.5%), Aedes aegypti (L.) (23.8%), and Culex nigripalpus Theobald (6.6%) during 1 yr of monthly sampling. Significant differences were detected among counties for abundances of Cx. quinquefasciatus and for percentage composition of that species and Ae. albopictus. Aerial images of habitats around each collection site were digitized, and coverages by each of 16 habitat variables were recorded. Abundances of Ae. aegypti were positively related to habitat variables associated with urbanization and negatively correlated to those reflecting rural characteristics. Multiple regression models of habitat selection explained similar proportions of variances in abundance of Ae. aegypti and Ae. albopictus, but signs of significant variables were opposite for these two species. No consistent trends of habitat associations were observed among counties for the two Culex spp. Co-occurrences of the four species in individual traps depended on container type (tub versus cup), and, for Aedes spp. with Culex spp., county. The results underscore the importance of scale in evaluating habitat selection and the utility of quantifiable habitat characteristics of intermediate scale to identify site characteristics favored by the arboviral vectors Ae. aegypti and Ae. albopictus.

RESUMEN Trampas de oviposición localizadas in tres condados del sur de Florida fueron colonizadas principalmente por Aedes aegypti (L) (23.8%), Aedes albopictus (Skuse) (34.5%), Culex quinquefasciatus Say (35.1%), and Culex nigripalapus Theobald (6.6%) en muestreos mensuales durante un año. Se encontraron diferencias significativas entre los condados en la abundancia de Cx quinquefasciatus y en el porcentaje de esa especie y de Ae. albopictus. Imágenes aéreas de cada sitio de colección fueron digitalizadas y la cobertura por cada una de 17 variables relacionadas con el habitáculo fué anotada. La abundancia de Ae. aegypti fué correlacionada positivamente con variables relacionadas a la urbanización, y negativamente con aquellas que reflejan características rurales. Modelos de regresión múltiple de selección de habitáculo explicaron proporciones similares de la varianza en abundancia de Ae. aegypti y de Ae. albopictus pero los signos de las variable significativas fueron opuestos para las dos especies. No SE encontraron patrones consistentes algunos entre los condados para las dos especies de Culex. Cohabitación de las cuatro especies en las trampas dependió del tipo de trampa (tinas o tazas) y, para Aedes spp con Culex spp., en el condado. Los resultados recalcan la importancia de la escala de medidas y la utilidad de características cuantificables del habitáculo a escala media para identificar características de sitios preferidos por los vectores de arboviruses Ae. aegypti y Ae. albopictus.

We evaluated the relationships between forest understory structure and the abundance of questing adult and nymphal blacklegged ticks, Ixodes scapularis Say (Acari: Ixodidae), in three Maine towns endemic for Lyme disease, 2001–2003. In fragmented New England woodlands, overabundant white-tailed deer, Odocoileus virginianus Zimmerman, overbrowse palatable species, allowing browse-resistant exotic-invasive species to replace native forest understory structures. We predicted there would be more ticks in plots dominated by exotic-invasive shrubs (such as Japanese barberry, Berberis thunbergii DC) than in plots dominated by native shrubs, ferns, or open understory. We assessed canopy composition and closure, tree basal area, litter composition, percentage of coverage and stem density of understory species, litter depth, soil moisture, and abundance of small mammals and white-tailed deer pellet groups. We used generalized linear mixed model analysis of covariance to determine the effect of understory structure on tick counts, controlling for continuous habitat and host covariates and adjusting for random spatial effects. There were twice as many adults and nearly twice as many nymphs in plots dominated by exotic-invasives than in plots dominated by native shrubs. Both adult and nymphal counts were lowest in open understory with coniferous litter. Adults were positively associated with increasing litter depth, medium soil moisture, and increasing abundance of white-footed deer mice, Peromyscus leucopus Rafinesque, and deer pellet group counts. Nymphs were positively associated with increasing litter depth, moderately wet soil, and mice. We concluded that deer browse-resistant exotic-invasive understory vegetation presented an elevated risk of human exposure to the vector tick of Lyme disease.

The succession of the planktonic bacterial community during the colonization by Culex (Diptera: Culicidae) mosquitoes of 0.1-ha treatment wetlands was studied using denaturing gradient gel electrophoresis (DGGE) methodology. Relationships between apparent bacterial diversity and ecological factors (water quality, total bacterial counts, and immature mosquito abundance) were determined during a 1-mo flooding period. Analysis of DGGE banding patterns indicated that days postflooding and temporal changes in water quality were the primary and secondary determinants, respectively, of diversity in bacterial communities. Lower levels of diversity were associated with later postflood stages and increases in ammoniacal nitrogen concentration and total bacterial counts. Diversity was therefore most similar for bacteria present on the same sampling date at wetland locations with similar flooding regimes and water quality, suggesting that wastewater input was the driving force shaping bacterial communities. Comparatively small changes in bacterial diversity were connected to natural processes as water flowed through the wetlands. Greater immature mosquito abundance coincided with less diverse communities composed of greater total numbers of bacteria. Five individual DGGE bands were directly associated with fluctuations in mosquito production, and an additional 16 bands were associated with hydrological aspects of the environment during the rise and fall of mosquito populations. A marked decline in mosquito numbers 21 d after inundation may have masked associations of bacterial communities and mosquito recruitment into the sparsely vegetated wetlands. DGGE was an effective tool for the characterization of bacteria in mosquito habitat in our study, and its potential application in mosquito ecology is discussed.

Flower odors are important signals for chemical communication between plants and flower visitors. Here, we studied the naïve responses of Culex pipiens pipiens biotype molestus Forskal 1775 (Diptera: Culicidae) to typical flower odors and assessed the learning capacity of mosquitoes to floral volatiles. The odor compounds used in the bioassay, phenyl acetaldehyde, veratrole, and 2-methoxyphenol, are typically found in the floral odor of Silene otites (L.) Wibel, a plant that is pollinated by nectar-drinking mosquitoes and moths, and/or in other closely related Silene species. Wind tunnel bioassays with a mixture of these compounds revealed that attraction of mosquitoes to odors was positively correlated with time passed since the last feeding. In single component bioassays, mosquitoes showed strong innate responses to phenyl acetaldehyde and only moderate or weak responses to veratrole and 2-methoxyphenol. Furthermore, in comparison with naïve mosquitoes, conditioned mosquitoes were significantly more attracted to the mixture and single volatiles. These results indicate that naïve mosquitoes are effectively attracted by appropriate floral scent compounds and that learning can increase the attractiveness of these compounds.

Glutathione S-transferases (GSTs) are soluble dimeric proteins that are involved in the metabolism, detoxification, and excretion of a large number of endogenous and exogenous compounds such as insecticides from the cell. In the current study, field specimens of Anopheles stephensi Liston, Anopheles fluviatilis James, and Anopheles culicifacies Giles collected from Sistan and Baluchistan province in Iran and subjected to World Health Organization susceptibility test. Only An. stephensi was resistant to 4% DDT. DNA extraction and rDNA-ITS2-polymerase chain reaction (PCR) for correct species identification, followed by amplification of GSTe2 gene, including exon I and II and full sequence of intron I, identified a 500-bp fragment in these three species. These fragments were purified and sequenced from both ends. The comparison of coding sequence of GSTe2 gene between these species and with Anopheles gambiae Giles showed 82 to 86% similarity at nucleic acid levels and identified nucleotide polymorphisms within An. culicifacies and An. stephensi populations. Species-specific differences have been detected in intron I of GSTe2 gene. This is in concordance with the previous studies and confirmed the conserved nature of intron sequence in GSTe2 gene of each species, probably useful as a molecular marker for species-specific identification. Phylogenetic analysis based on rDNA-ITS2, and coding (exon I and II) and noncoding sequences of GSTe2, showed the systematic relatedness between Iranian malaria vectors and the possibility of using these sequences in both differentiation of Anopheles species and defining their evolutionary relationship with the only available GSTe2 sequence of An. gambiae. These data may be useful for implementation and evaluation of malaria control programs in aspects of population genetics and molecular resistance.

Anopheles funestus Giles (Diptera: Culicidae) is one of Africa’s major malaria vectors. To understand population structure within An. funestus, various molecular markers have recently been developed. We investigated the impact of the Rift Valley on one such molecular marker, a polymerase chain reaction-restriction fragment length polymorphism (RFLP). This system distinguishes An. funestus populations into types M, W, and MW. Generally, these types correlate between geographical location and RFLP type, whereby M associates essentially with eastern Africa, W with western and central Africa, and MW with southern Africa. In total, 606 specimens were screened from 12 countries. Specimens from southern African localities were of the expected MW-type with the exception of the sample from Malawi, which showed all three types. The specimens from Tanzania showed the M- and MW-types, whereas specimens from Kenya showed M- and W-types. We also recorded different RFLP types not recorded previously. Type Y was recorded in Malawi, and Z-type was recorded from four localities: Angola, Malawi, Ghana, and Zambia.

A sample of Aedes aegypti (L.) (Diptera: Culicidae) from Santiago de Cuba, Cuba, with a high level of propoxur resistance compared with the reference susceptible Rockefeller strain (12.60× at the 50% lethal concentration [LC₅₀] and 18.08 at the 90% lethal concentration [LC₉₀]), with a 4.3% frequency of insensitive acetylcholinesterase (AChE) frequency, was subjected to propoxur selection for 13 successive generations to increase the frequency of this resistance mechanism in Ae. aegypti. High resistance to propoxur was developed during this selection (41.73-fold), and the frequency of insensitive AChE mechanism was increased 13.25-fold. Other mechanisms (overproduced esterases, glutathione transferases, or monooxygenases) were not detected in the propoxur-selected strain. The selection of an insensitive AChE resistance mechanism in Ae. aegypti has important implications and will be a valuable resource for genetic studies and molecular characterization of the ace gene mutation(s) associated with insecticide resistance in Ae. aegypti.

In this study, the efficacy of pyriproxyfen and spinosad, alone and in combination, was evaluated against the dengue vector Aedes aegypti (L.). Larval bioassays were carried out on susceptible mosquito larvae to determine the concentration–mortality responses of mosquitoes exposed to each insecticide alone and in mixture. Synergism between pyriproxyfen and spinosad was determined by the calculation of a combination index (CI) by using the isobologram method. For pyriproxyfen, LC₅₀ and LC₉₅ were 1.1 × 10⁻⁴ (1.0 × 10⁻⁴–1.1 × 10⁻⁴) and 3.2 × 10⁻⁴ (2.9 × 10⁻⁴–3.6 × 10⁻⁴) mg/liter, respectively. Pyriproxyfen acted at very low concentrations by inhibiting the adult emergence of Ae. aegypti (97% inhibition rates at 3.3 × 10⁻⁴ mg/liter). Spinosad activity was ≈500 times lower than that of pyriproxyfen against the Bora strain, with LC₅₀ and LC₉₅ values estimated at 0.055 (0.047–0.064) and 0.20 (0.15–0.27) mg/liter, respectively. A binary mixture of pyriproxyfen and spinosad was realized at the ratio 1:500 by considering the values of the LC₅₀ obtained for each product. The LC₅₀ and LC₉₅ of the mixture were 0.019 (0.016–0.022) and 0.050 (0.040–0.065) mg/liter, respectively. The mixture combined both the larvicidal activity of spinosad and the juvenoid action of pyriproxyfen. From the LC₇₀ to LC₉₉, a significant synergism effect was observed between the two insecticides (CI ranged from 0.74 to 0.31). This strong synergism observed at high concentrations allows a reduction by five and nine-fold of pyriproxyfen and spinosad amounts to kill almost 100% mosquitoes. Combination of pyriproxyfen and spinosad may then represent a promising strategy to improve mosquito control in situations with insecticide-resistant Aedes dengue vectors.

The larvicidal activity of chlorpyrifos-methyl and temephos was evaluated against Culex pipiens L. (Diptera: Culicidae) in septic tanks in Antalya, Turkey. Chlorpyrifos-methyl (Pyrifos MT 25 emulsifiable concentrate [EC]) was evaluated at application rates of 0.04, 0.08, and 0.12 mg active ingredient (AI)/liter, and temephos (Temeguard 50 EC) was evaluated at 0.02, 0.04, and 0.06 mg (AI)/liter during a 21-d study. Generally, overall larval reduction in septic tanks from single- and multifamily dwellings treated with either larvicide was significantly greater than pretreatment levels and control tanks for the duration of the study. At 14 d posttreatment, duration of control was greatest in multifamily tanks treated with chlorpyrifos-methyl at the highest application rate with similar levels of control through 21 d for single-family dwellings (range 97–100%). Septic tanks from both types of family dwellings treated at the highest application rate of temephos resulted in >90% reduction through day 21 (range 91–100%). Laboratory bioassays of septic tank water treated at field application rates, without daily dilution, revealed that complete larval mortality was achieved for 21 d at each application rate and formulation. It is thought that daily addition of water and organic matter to the septic tanks in the single and multifamily dwellings influenced the duration of effectiveness of the larvicides.

Many of the previously characterized allergens of house dust mites are known to be proteases, and this enzymatic activity is thought to contribute to their allergenicity. Other astigmatid mites, including stored-product mites and the ectoparasitic itch mite, Sarcoptes scabiei De Geer, are also known to be allergenic, but little or nothing is known about their enzymatic activities. The purpose of this study was to characterize the enzymatic activities present in extracts of the parasitic itch mite and from eight other species of free-living astigmatid mites. Extracts were prepared from one parasitic mite (S. scabiei), five stored-product mites (Chortoglyphus arcuatus (Troupeau), Lepidoglyphus destructor (Schrank), Blomia tropicalis Bronswijk, Cock, Oshima, Tyrophagus putrescentiae (Schrank), and Acarus siro L.), and three house dust mites [Dermatophagoides farinae Hughes, Dermatophagoides pteronyssinus (Troussart), and Euroglyphus maynei (Cooreman)]. ApiZym strips were used to screen for the presence of 19 individual enzyme activities. Digestion of nine other substrates was evaluated by spectrophotometric or electrophoretic methods. All mite extracts exhibited some form of phosphatase, esterase, aminopeptidase, and glycosidase activity, although their substrate specificities varied considerably. Itch mite extract did not possess detectable serine peptidase activity nor was it able to hydrolyze gelatin or casein, whereas all other mite extracts exhibited these activities. Storage mite extracts possessed enzymes capable of degrading the widest range of substrates, whereas itch mite extract had the most limited proteolytic capacity. Extracts of nine species of allergy-causing astigmatid mites contain wide and diverse repertoires of enzymatic activities. These catalytic activities may be important contributors to the induction and manifestation of inflammatory and immune responses to mites in patients.

The effect of salivary gland extract (SGE) and saliva from the tick Ixodes ricinus (L.) on the interaction of Borrelia afzelii spirochetes with mouse macrophages as well as on the borreliacidal effect of calf serum was studied. SGE reduced both the number of phagocytosing cells and phagocytosed bacteria. An inhibitory effect of SGE on the killing of spirochetes by the alternative pathway of complement activation also was observed. Both SGE and saliva down-regulated production of proinflammatory cytokine tumor necrosis factor-α by macrophages stimulated with interferon-γ and live B. afzelii spirochetes. The production of another macrophage cytokine, interleukin-6, remained unchanged. SGE and saliva exerted a different effect on the production of nitric oxide by stimulated macrophages. Whereas SGE up-regulated NO production, saliva decreased it. The significance of immunosuppressive effects of tick saliva for the transmission of Borrelia spirochetes is discussed.

Malaria transmission in Africa is a dynamic and complex system that is so far superficially understood. Further knowledge is required to improve control of the disease. In the present report, we highlight the contribution of the so-called “secondary” malaria vectors to the overall parasite transmission intensity in several sites across Cameroon, through a retrospective analysis of surveys from the Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale database. In total, 48,490 female anophelines belonging to 21 different species were collected between October 1998 and March 2003. Anopheles gambiae Giles, Anopheles arabiensis Patton, Anopheles funestus Giles, Anopheles nili (Theobald), and Anopheles moucheti Evans represented 89% of the total anopheline fauna. Beside these major vectors, malaria parasites or their circumsporozoite proteins were found in nine secondary malaria vectors: Anopheles ovengensis Awono-Ambene et al., Anopheles carnevalei Brunhes et al., Anopheles coustani Laveran, Anopheles hancocki Edwards, Anopheles marshallii (Theobald), Anopheles paludis Theobald, Anopheles pharoensis Theobald, Anopheles wellcomei Theobald, and Anopheles ziemanni Grünberg. The mean infection rate of secondary vectors (1.36%) was significantly (P < 0.001) lower than that of major vectors (3.08%). An. pharoensis and An. ovengensis were repeatedly found infected by Plasmodium falciparum Welch and contributed substantially to the total malaria transmission intensity in some areas where they were abundant. Both species have strong exophilic and/or exophagic habits such that they might elude vector control directed against endophilic and endophagic malaria vectors.

The efficiency of laboratory colonies of mosquitoes such as Anopheles stephensi Liston, Aedes aegypti (L.) Liverpool strain, Ae. aegypti wild type, Aedes albopictus (Skuse), Culex tritaeniorhynchus Giles, Culex sitiens Wiedemann, and Armigeres subalbatus Coquillett in supporting the development of Wuchereria bancrofti (Cobbold) (Spirurida: Onchocercidae) microfilariae to infective larvae was investigated. The mosquitoes were fed on heparinized microfilaremic human blood by using a membrane-feeding unit with Parafilm as membrane. The rate of infection, parasite development, and parasite burden were compared with that in the known vector mosquito Culex quinquefasciatus Say. Cx. quinquefasciatus showed the highest percentage of infection, followed by Ae. aegypti Liverpool strain and An. stephensi. The rate of development of the parasite was more or less similar in all the three species, and infective larvae were found on day 13. When the larvae were harvested on day 17, Cx. quinquefasciatus yielded the highest numbers, followed by Ae. aegypti Liverpool strain and An. stephensi. The percentage of infection was low, and the development was slow in Cx. tritaeniorhynchus compared with the other susceptible species. The parasite developed to second-stage larvae only by day 22 and to infective larvae by day 28. When 2-wk-old Cx. tritaeniorhynchus were fed on microfilaremic blood, they could develop the parasite to infective larvae by day 13 postfeeding. All other species of mosquitoes tested were found to be refractory to parasite development. It is shown that Cx. quinquefasciatus is the most suitable mosquito host for the production of infective larvae. However, Ae. aegypti Liverpool strain, which is commonly used for Brugia malayi filarial parasite, also can be used for generation of W. bancrofti infective larvae to circumvent the problem of maintaining two mosquito species.

Oviposition activity and West Nile virus (family Flaviviridae, genus Flavivirus, WNV) infection rates were assessed for members of the Culex pipiens complex from July through December 2002 by using gravid traps placed at four ecologically different sites in the southern portion of the hybrid zone in Shelby County, TN. Molecular assays identified three members of the Cx. pipiens complex: Cx. pipiens pipiens L., Cx. p. quinquefasciatus Say, and Cx. p. pipiens–Cx. p. quinquefasciatus hybrids (hybrids). The Cx. pipiens complex accounted for 90% of mosquitoes collected in gravid traps. All 285 WNV-positive mosquitoes were Culex mosquitoes, and 277 (97%) were Cx. pipiens complex mosquitoes. Infection rates among members of the Cx. pipiens complex were not significantly different. Infection rates were significantly higher at two urban sites than at a rural site, and WNV was not detected at a forested site. At urban sites, abundances of members of the Cx. pipiens complex corresponded to a simple latitude model of the hybrid zone. Cx. p. quinquefasciatus was most abundant (46.4%), followed by hybrids (34.1%) and Cx. p. pipiens (19.5%). The relative abundances at a rural site were reversed with Cx. p. pipiens (48.4%) being most abundant. This demonstrates that spatial habitat variation may profoundly influence the distribution of members of the Cx. pipiens complex within the hybrid zone. Members of the Cx. pipiens complex did not display different oviposition patterns. However, oviposition patterns assessed hourly at urban and rural sites were significantly different. At urban sites, oviposition activity of Cx. pipiens complex mosquitoes was bimodal with an evening peak associated with sunset and a morning peak associated with sunrise. At the rural site, the evening peak was pronounced and the morning peak weak and similar to nighttime activity.

Verrallina funerea (Theobald) (Diptera: Culicidae) is a brackish water mosquito species found most commonly in Indonesia, Papua New Guinea, and the northeastern coastal regions of Australia. Aspects of the vector competence of this species for Barmah Forest virus (family Togaviridae, genus Alphavirus, BFV) and Ross River virus (family Togaviridae, genus Alphavirus, RRV), two medically important arboviruses in Australia, were investigated. Laboratory-reared Ve. funerea were moderately susceptible to experimental infection with BFV (median cell culture infectious dose of 10^3.6 per mosquito) and were capable of transmission to suckling mice (52% after a 9–12-d extrinsic incubation period). Maximum salivary gland infections for BFV (65%) and RRV (50%) were observed 8 and 10 d postinfection, respectively. To examine any regional differences in vector competence, field populations (separated by up to 200 km) of Ve. funerea and Aedes vigilax (Skuse) from southeastern Queensland and northern New South Wales were fed BFV and RRV, and subsequent infection rates were compared. For both viruses, no statistically significant variations in body, disseminated, or salivary gland infection rates were found in either Ve. funerea or Ae. vigilax. The results from this study indicate that Ve. funerea may have an important role as an amplification vector during outbreaks of both viruses and that local government authorities should rapidly treat brackish water habitats to control this species during periods of increased disease activity.

An earlier in vitro screening of N,N-diethyl-3-methylbenzamide (Deet) and N,N-diethylphenylacetamide (DEPA) analogs showed that two DEPA analogs, N,N-diethyl(3-bromophenyl)acetamide and N,N-diethyl[(α,α,α-trifluoro-m-tolyl)]acetamide, and one Deet analog, N,N,-diethyl[3-(trifluoromethyl)]benzamide, had biting-deterrent activities that were superior to Deet against Aedes aegypti (L.) and Anopheles stephensi Liston. In the current study, the three analogs and (1S,2′S)-methylpiperidinyl-3-cyclohexene-1-carboxamide (SS220) were applied topically to the skin of human volunteers at 24 nmol compound/cm² skin and compared with the activity of Deet at the same dose against biting by Ae. aegypti, An. stephensi, and Phlebotomus papatasi Scopoli females. SS220 proved to be as effective as Deet against Ae. aegypti and P. papatasi but more effective than Deet against An. stephensi. Contrary to the earlier in vitro tests, results with humans (in vivo testing) showed that neither of the DEPA analogs nor the Deet analog performed more effectively than Deet against the insects. The in vivo results showed that the analogs were not sufficiently effective to warrant further development. Notably, in vivo and in vitro methods used in discovery of personal protection chemicals for human use against blood-feeding flies can both be effective discriminating tools, but results obtained with the respective methods may not always agree. Ultimately, we surmise that in vivo testing methods with humans must be used to discriminate among compounds that superficially seem effective when screened using an in vitro method.

Long-term control of Chagas disease requires not only interruption of the human transmission cycle of Trypanosoma cruzi Schyzotrypanum, Chagas, 1909 by controlling its domestic triatomine vectors but also surveillance to prevent reinfestation of residences from sylvatic or persistent peridomestic populations. Although a number of potential risk factors for infestation have been implicated in previous studies, the explanatory power of resulting models has been low. Two years after cessation of triatomine vector control efforts in the town of Chalcatzingo, Morelos, 78 environmental, socioecological, and spatial variables were analyzed for association with infestation by Triatoma pallidipennis Stal 1872 (Hemiptera: Reduviidae: Triatominae), the principal vector of T. cruzi. We studied 712 residences in this rural community to identify specific intradomestic and peridomestic risk factors that predicted infestation with T. pallidipennis. From numerous characteristics that were identified as correlated with infestation, we derived multivariate logistic regression models to predict residences that were more or less likely to be infested with T. pallidipennis. The most important risk factors for infestation included measurements of house age, upkeep, and spatial location in the town. The effects of certain risk factors on infestation were found to be modified by spatial characteristics of residences. The results of this study provide new information regarding risk factors for infestation by T. pallidipennis that may aid in designing sustainable disease control programs in rural Mexico.

Ambyomma americanum (L.) (Acari: Ixodidae) is an aggressive tick that feeds on humans during all postembryonic life stages. In many regions of the United States, it is the tick most commonly found attached to humans. Public health interest has grown recently, due to the recognition of new human pathogens transmitted by A. americanum and the expanding distribution of the tick. A. americanum is a vector of several bacteria pathogenic to humans. Ehrlichia chaffeensis and Ehrlichia ewingii cause moderate-to-severe febrile illness. “Rickettsia amblyommii,” a member of the spotted fever group Rickettsia, also has recently been implicated as a possible human pathogen based on serologic evidence from persons recovering from illness after a tick bite. We have determined the prevalence of infection of Ehrlichia chaffeensis, E. ewingii, “Borrelia lonestari,” and R. amblyommii within A. americanum ticks from 29 sites in nine states. Overall infection prevalences were 4.7% for E. chaffeensis (range, 0–27%), 3.5% for E. ewingii (range, 0–18.6%), 2.5% for B. lonestari (range, 0–12.2%), and 41.2% for R. amblyommii (range, 0–84.0%). In addition, 87 ticks (4.3%) were infected with two or more bacteria. This report documents new distribution records for E. ewingii, B. lonestari, and R. amblyommii and underscores the nonhomogeneous distribution of pathogen foci of infection. Additional surveillance throughout the range of A. americanum is warranted to increase physician and public awareness of the risk of disease to humans from exposure to the agents transmitted by this tick.

To evaluate their potential importance in the transmission of ixodid tick-borne borrelioses in Monmouth County, NJ, we collected host-seeking Ixodes scapularis Say and Amblyomma americanum (L.) (Acari: Ixodidae) adults and nymphs to determine relative encounter frequencies and the infection prevalence of selected Borrelia spp. in their respective tick vectors. We also reviewed records of all ticks submitted for identification by the public in Monmouth County during 2001–2005. Relative abundance of the two species varied markedly among sites. Adult encounter frequencies for the two species were similar; however, A. americanum nymphs were encountered 3 times more frequently than I. scapularis nymphs. Of 435 ticks submitted by the public, 50.1 and 38.9% were I. scapularis and A. americanum, respectively. However, during May through August, the peak Lyme disease transmission season in New Jersey, significantly more submitted ticks were A. americanum (55.9%), compared with I. scapularis (34.1%). Polymerase chain reaction analysis of 94 I. scapularis and 103 A. americanum adults yielded infection prevalences of 31.9% for B. burgdorferi and 5.8% for B. lonestari, respectively. Although the infection prevalence of B. burgdorferi in I. scapularis was considerably higher than the infection prevalence of B. lonestari in A. americanum, the higher encounter frequencies for A. americanum compared with I. scapularis observed in this and other studies may result in increased risk of acquiring exposure to A. americanum-transmitted pathogens. The potential public health implications of these results are discussed.

Precise developmental data for forensic indicator blow fly species are essential for accuracy in the estimate of the post-mortem interval (PMI). Why, then, does the determination of the PMI result in conflicting time frames when published conspecific developmental data are used? To answer this question, we conducted constant temperature trials between the developmental minimum temperature and upper threshold temperatures (8–32°C) on the forensically important blow fly species Phormia regina (Meigen) (Diptera: Calliphoridae). Flies were reared using two designs to quantify sources of variation. We measured rearing container temperatures and internal growth chamber temperatures by using thermocouples to accurately record temperatures experienced by larvae and to construct a degree-day model. Differences in experimental design, as seen across temperature studies for this fly species, did not significantly impact larval development. We also found that using set chamber temperatures rather than rearing container temperatures altered the final degree-day model. Using any minimum threshold (including an empirically determined true minimum) other than that from linear interpolation (x-intercept) violated degree-day assumptions and invalidated estimates of the PMI. We observed the minimum developmental temperature to be higher (14°C) than that generated under the x-intercept method (5.46°C) by using data from oviposition to adult emergence. This difference along with the noted difference in accumulated degree-days (using different base temperatures) suggests a need for additional experimentation on other forensically important fly species at low temperature thresholds to help with development of curvilinear models. Former and current estimates of the PMI may be inaccurate if the process to determine the time frame ignored degree-day model assumptions or was based upon questionable data sets.

Workshops are used for educating law enforcement personnel on the application of entomological, anthropological, and botanical techniques to gather forensically important information from a body recovery site. From 8 to 11 June 2004, such a workshop was conducted in the metropolitan area of Charlotte, NC, by the American Academy of Applied Forensics at Central Piedmont Community College. For this workshop, three pig carcasses weighing individually between 40 and 60 kg were placed in the field 4 June, whereas three pigs similar in size were placed in the field 7 June. During the afternoon session on 11 June, workshop participants collected three Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) third instar larvae from a pig carcass placed in the field on 7 June. These data represent the first records of this forensically important insect in North Carolina; furthermore, these data provide evidence of this species expansion into new geographic regions of the United States. This finding is an example of the benefits derived from an experiential and interdisciplinary approach to educating death scene investigators. Learners acquired new knowledge, put it into practice through the “body” recovery exercise, and ultimately contributed to science by way of the discovery and first documentation of a forensically important insect previously not known to inhabit North Carolina.