The epidemiology of vector-borne pathogens is determined by mechanisms and interactions at different scales of biological organization, from individual-level cellular processes to community interactions between species and with the environment. Most research, however, focuses on one scale or level with little integration between scales or levels within scales. Understanding the interactions between levels and how they influence our perception of vector-borne pathogens is critical. Here two examples of biological scales (pathogen transmission and mosquito mortality) are presented to illustrate some of the issues of scale and to explore how processes on different levels may interact to influence mosquito-borne pathogen transmission cycles. Individual variation in survival, vector competence, and other traits affect population abundance, transmission potential, and community structure. Community structure affects interactions between individuals such as competition and predation, and thus influences the individual-level dynamics and transmission potential. Modeling is a valuable tool to assess interactions between scales and how processes at different levels can affect transmission dynamics. We expand an existing model to illustrate the types of studies needed, showing that individual-level variation in viral dose acquired or needed for infection can influence the number of infectious vectors. It is critical that interactions within and among biological scales and levels of biological organization are understood for greater understanding of pathogen transmission with the ultimate goal of improving control of vector-borne pathogens.

Simulium (Gomphostilbia) piroonae sp. nov. is described on the basis of females, males, pupae, and mature larvae collected in Mae Hong Son Province, Thailand. This new species is placed in the chumpornense subgroup of the varicorne species-group in the subgenus Gomphostilbia by having the antenna with eight flagellomeres, the pleural membrane bare, the female subcosta lacking hairs, and the pupal gill basally divided into two somewhat inflated branches. It is distinguished from all 10 known species of this group by the pupal gill with six filaments. Keys to identify 11 species of the varicorne species-group are provided for females, males, pupae, and mature larvae.

The small genus Trichorhynchiella Fain, 1995, including two species of permanent bird ectoparasites belonging to the family Harpirhynchidae (Acariformes: Cheyletoidea), is revised. The generic diagnosis is emended. The type species, Trichorhynchiella paddae Fain, 1995 from Lonchura oryzivora (L., 1758) (Passeriformes: Estrildidae) from Southeast Asia and Trichorhynchiella phleocryptes sp. n. from Phleocryptes melanops (Viellot, 1817) (Passeriformes: Furnariidae) from Argentina are redescribed and described, respectively. The phenomenon of ovoviviparity inherent to females of this genus is briefly discussed. In almost immobile physogastric females of Trichorhynchiella, ovoviviparity eliminates necessity to attach eggs to the host body.

The Shannoni complex, comprising sand flies belonging to the subgenus Psathyromyia (Psathyromyia) Barretto, consists of several species, of which the females have banana-shaped spermathecae and the males have digitiform parameres on the terminalia. Among these species, Psathyromyia shannoni (Dyar) and two taxa considered as its junior synonyms (Phlebotomus limai Fonseca and Phlebotomus bigeniculatus Floch & Abonnenc), Psathyromyia pestanai (Barretto & Coutinho), and a new species are the focus of this study. On the basis of morphological and morphometric characters, Psathyromyia bigeniculata (Floch and Abonnenc) stat. rev.; comb. n. and Psathyromyia limai (Fonseca) stat. rev.; comb. n. are resurrected from the synonymy of Pa. shannoni. Pa. pestanai is proposed as a new junior synonym of Pa. limai. Psathyromyia ribeirensis sp. n., occurring in the middle and upper Ribeira Valley in the state of São Paulo, Brazil is described. Pa. limai, described from the Serra da Cantareira (São Paulo municipality) and also found in the lower Ribeira Valley and on the adjacent coastal plain, is morphologically very close to the new species.

In addition to being a major nuisance biter, the lone star tick, Amblyomma americanum (L.), is increasingly recognized as an important vector of pathogens affecting humans, domestic animals, and wildlife. Despite its notoriety, efforts have been lacking to define the spatial occurrence of A. americanum in the continental United States with precision beyond that conveyed in continental-scale distribution maps. Here we present a county-level distribution map for A. americanum generated by compiling collection records obtained from a search of the published literature and databases managed by the USDA, U.S. National Tick Collection, and Walter Reed Biosystematics Unit. Our decadal and cumulative maps, which visually summarize 18,121 collections made between 1898 and 2012, show that A. americanum is either established (≥six ticks or ≥two life stages) or reported (<six ticks of a single life stage or number of ticks not specified) in 1,300 counties distributed among 39 states and the District of Columbia. Our cumulative map depicts a species with a core distributional area in the southern part of the eastern United States, but that also occurs further north, especially along the Atlantic Coast and into the Midwest. Although our decadal maps suggest a northward shift in the tick's distribution in recent decades, the lack of systematic tick surveillance makes this difficult to confirm. The data presented herein should aid in identifying areas posing risk for A. americanum-associated illnesses and environmental correlates that define the tick's distributional limits.

A 100 yr (1911–2011) examination of tick submissions was compiled from the U.S. National Tick Collection and three state databases to determine tick species occurrence in Nebraska. Sixteen tick species were identified including Amblyomma americanum (L.), Dermacentor variabilis (Say), Dermacentor albipictus (Packard), Dermacentor andersoni Stiles, Haemaphysalis leporispalustris (Packard), Rhipicephalus sanguineus (Latreille), and Otobius megnini (Dugès). Amblyomma maculatum Koch and Ixodes scapularis Say were identified in only two and four submissions, respectively, but all identifications have occurred after 1990. County submissions were associated with county population, forested area, and number of recreation areas.

Embryos of Lucilia (Phaenicia) sericata (Meigen) (Diptera: Calliphoridae), the green blowfly, were successfully cryopreserved by vitrification in liquid nitrogen and stored for 8 yr. Embryos incubated at 19°C for 17 h after oviposition were found to be the most appropriate stage to cryopreserve. Removal of the embryonic surface water was done using 2-propanol before the alkane treatment to permeabilize the embryo. Exposure to 2-propanol for >10 s caused necrotic tissue damage in the embryos. Among the alkanes used, hexane was found to be a superior permeabilizing solvent compared with heptane or octane, with embryo hatching rates on par with the controls. Treatment with the vitrification solution for <12 min was insufficient to vitrify the embryos. Treatment time in the solution beyond 15 min reduced embryo viability. However, the percentage of embryos vitrifying upon exposure to liquid nitrogen vapor remained constant after 12 min of treatment. Long-term storage was initiated in 2004, and the mean hatch percentage recorded then for the short-term cryopreserved embryos was 9.51%. When the long-term stored samples were retrieved in 2012, 8.47% of the embryos hatched, 66.36% larvae pupariated, and 36.96% of the pupae eclosed. Recent optimization of the technique has resulted in a hatch rate of 34.08 ± 15.5%, of which 67.5% of the larvae pupariated and 72% of the pupae eclosed to normal flies.

The efficacy of using predators for the biological control of mosquito disease vectors will be reduced if mosquito larvae respond to predator presence. The larvae of two mosquito species were investigated to study whether they responded to predator kairomones by increasing surface filter-feeding, which is a less active and thus less risky feeding strategy than bottom feeding. Culex quinquefasciatus Say is normally found in highly polluted water, where it will have little contact with predators. Except for some third instars, its larvae showed no response to four different types of predators. Culiseta longiareolata Macquart, living in rain-filled rock pools, is frequently attacked by a range of predators. All instars tested (second, third, and fourth instars) strongly responded to chemicals from dragonfly nymphs (Crocothemis erythraea Brullé), damselfly nymphs (Ischnura evansi Morton), and the fish Aphanius dispar Ruppel. However, they did not respond to final-instar water scorpions (Nepa cinerea L.), which would not feed on the mosquito larvae. Second- and third-instar Cs. longiareolata produced the same response to chopped up mosquito larvae as they did to dragonfly nymphs, but fourth instars produced a significantly stronger response to dragonfly nymphs—both those unfed and those fed in situ. Thus, Cs. longiareolata not only identified different predators and responded accordingly, but also responded to conspecific alarm pheromones. Cx quinquefasciatus showed little response to predators or to alarm pheromones from damaged conspecific larvae.

Mosquito larvae often exhibit different behaviors depending on the aspects of the aquatic environment, including the presence of different physical factors and detrital food sources. Regardless of these physical differences, different genera also devote different amounts of time to different behaviors. To determine if differences existed among four focal mosquito species (Aedes albopictus (Singh), Aedes triseriatus (Say), Culex quinquefasciatus (Say), Culex coronator Dyar & Knab), we recorded behaviors under different food environments (animal detritus, leaf detritus, and inoculum inert material) and depths (shallow and deep). Based on past work, we predicted that larval mosquitoes in the genus Culex would spend more time filtering or resting at the surface of containers, whereas Aedes mosquitoes would spend more time browsing on surfaces. Behaviors were recorded for 30 min and were used to generate instantaneous scan census of behavior (thrashing, browsing, and resting or filtering) and locations (top, middle, bottom, wall, and detritus) of each larva every minute. There were significant differences in behaviors among the three detritus types and the four species (Culex generally different than Aedes), as well as a significant interaction between depth and detritus type. Consistent with predictions, Culex species spent more time filtering or resting, whereas Aedes larvae spent more time browsing on detritus. However, all four species changed their behavior similarly among the different environments, and Cx. coronator exhibited some similar behaviors as the two Aedes species. These behavioral differences may aid in explaining performance differences between different species and outcomes of interspecific encounters, which in turn can affect adult emergence and patterns of disease.

Field-collected female Psorophora howardii (Coquillett), Psorophora ciliate (F.), and Psorophora ferox (Humboltd) mosquitoes were tested in laboratory conditions to measure body size, blood engorgement duration, bloodmeal size, fecundity, and egg morphology. Mean bloodmeal size was significantly different among the three species of mosquitoes, whereas there was no difference in blood engorgement duration. Mean body weights and wing lengths of Ps. howardii and Ps. ciliata were significantly greater than Ps. ferox. Seven days after bloodmeals, oviposition rates for Ps. howardii, Ps. ciliata, and Ps. ferox were 18.8, 56.2, and 0%, respectively. The mean number of total eggs produced per female for the three species was 59, 81, and 73, respectively. Mean egg lengths of Ps. howardii and Ps. ciliata were significantly greater than Ps. ferox, and egg diameters for each of the three species were significantly different from one another. Length per diameter ratios of Ps. howardii and Ps. ciliata were significantly smaller than Ps. ferox. Bloodmeal size was positively related to body weight, but not related to blood engorgement duration, and the total egg number was positively related to bloodmeal size.

In southern Punjab, Pakistan, Muzaffargarh District is known to have insecticideresistant Anopheles and drug-resistant Plasmodium spp. In this part of the country, five anopheline mosquitoes, Anopheles stephensi Liston, Anopheles culicifacies Giles, Anopheles fluviatilis James, Anopheles superpictus Grassi, and Anopheles subpictus Grassi (Diptera: Culicidae) are known as malaria vectors. Among these, An. culicifacies is the primary and An. stephensi is the secondary malaria vector. Outbreaks of malaria usually occur after rainy episodes. We conducted field surveys to collect field strains of An. culicifacies and An. stephensi mosquitoes from different areas of Muzaffargarh District. We determined susceptibility and irritability levels of their adult stages to the discriminative dose of different insecticides. For this purpose, we used World Health Organization's established criteria for assessment. Mortality was calculated after 1 h exposure and for 24 h recovery period for various insecticides. An. stephensi was found to be significantly resistant to dichlorodiphenyltrichloroethane (DDT, an organochlorine), dieldrin (a chlorinated hydrocarbon), and malathion (organophosphorus), with lethal times (LT₅₀) of 83.17, 52.48, and 37.53, respectively. However, the species was significantly sensitive to permethrin, deltamethrin (pyrethroids), and fenitrothion (organophosphate) with LT₅₀ of 2.85, 2.34, and 13.18, respectively. Among these, permethrin showed more promising results against adult An. stephensi. When analyzed for irritancy, we found that among pyrethroids, permethrin was the most irritant insecticide for both An. stephensi and An. culicifacies. DDT and dieldrin showed least irritancy with 0.42 ± 0.08 and 0.77 ±0.12 takeoffs per minute per adult, respectively, against An. stephensi. The mean number of takeoffs per minute per adult with permethrin showed significant irritancy for permethrin when compared with DDT. Based on this study, we conclude that the use of organochlorine (DDT) and chlorinated hydrocarbon (dieldrin) should not be reintroduced in Malaria Control Programme in Pakistan until there is enough evidence to do so at any stage in future, and the use of pyrethroids should continue, with preference to permethrin for better control of malaria by indoor residual spraying.

Repellent efficacy of the plant-based repellent, TT-4302 (5% geraniol), was compared with 16 other products in laboratory arm-in-cage trials against Aedes aegypti (L.). Eight repellents (Badger, BioUD, Burt's bees, California Baby, Cutter Natural, EcoSMART, Herbal Armor, and SkinSmart) exhibited a mean repellency below 90% to Ae. aegypti at 0.5 h after application. Three repellents (Buzz Away Extreme, Cutter Advanced, and OFF! Botanicals lotion) fell below 90% repellency 1.5 h after application. TT-4302 exhibited 94.7% repellency 5 h posttreatment, which was a longer duration than any of the other repellents tested. The positive control, 15% DEET (OFF! Active), was repellent for 3 h before activity dropped below 90%. Additional arm-in-cage trials comparing TT-4302 with 15% DEET were carried out against Anopheles quadrimaculatus Say. At 6 h after treatment, TT-4302 provided 95.2% repellency while DEET exhibited 72.2%. In North Carolina field trials, TT-4302 provided 100% repellency 5 h after application against Aedes albopictus Skuse while DEET provided 77.6% repellency. These results demonstrate that TT-4302 is an efficacious plant-based repellent that provides an extended duration of protection compared with many other commercially available products.

Head lice infestations are very common in children aged between 3 and 12 yr old. The eggs of the head louse are difficult to remove and remain firmly attached to the hair even after any head louse treatment. Solid in vitro and in vivo evidence to support the use of any of the proposed products to facilitate nit removal is scarce. The objective of the current study was to determine the efficacy of several products to remove eggshells from human hair using an objective measurement procedure. Water and ordinary hair conditioner significantly facilitated the removal of nits in vitro. We found no difference between ordinary conditioner and products specifically marketed for the purpose of nit removal. Other products such as formic acid solution and almond oil did not have a beneficial effect.

The objective of this study was to assess the effectiveness of BG-Sentinel (BGS) traps for mass trapping at the household level to control the dengue vector, Aedes aegypti (L.), in Manaus (Brazil) by performing a cluster randomized controlled trial. After an initial questionnaire and baseline monitoring, 6 out of 12 clusters were randomly allocated to the intervention arm, where participating premises received one BGS trap for mass trapping. The other six clusters did not receive traps and were considered as the control arm. Biweekly monitoring with BGS in both arms assessed the impact of mass trapping. At the end of the study, a serological survey was conducted and a second questionnaire was conducted in the intervention arm. Entomological monitoring indicated that mass trapping with BGS traps significantly reduced the abundance of adult female Ae. aegypti during the first five rainy months. In the subsequent dry season when the mosquito population was lower, no effect of mass trapping was observed. Fewer Ae. aegypti females were measured in the intervention arm during the next rainy period, but no significant difference between arms was observed. The serological survey revealed that in participating houses of mass trapping areas recent dengue infections were less common than in control areas, although this effect was not statistically significant. The majority of participants responded positively to questions concerning user satisfaction. Our results suggest that BGS traps are a promising tool which might be deployed as part of dengue control programs; however, further investigations and larger scale studies are necessary.

A southern house mosquito Culex quinquefasciatus Say colony was established from surviving late instars and pupae from a semifield evaluation on Natular XRG (a granular formulation containing 2.5% spinosad). The initial lethal levels of Natular XRG against this colony were determined in the laboratory for the first-generation progeny (designated as F₁). Selection pressure was applied at LC_70–90 levels to 10,000–15,000 late third- and early fourth-instar larvae of each generation with Natular XRG. Susceptibility changes in response to selection were determined every other generation, where a gradual and steady decline in susceptibility occurred from generation F₁ to F₃₅, followed by significant decline from generations F₃₇ to F₄₅ For reference purposes, susceptibility of freshly collected wild populations as well as a laboratory colony of the same species was also determined concurrently, which fluctuated within a slightly wider range for the wild populations and a tighter range for the laboratory colony. By comparing with wild populations and laboratory reference colony, tolerance to spinosad was observed from generations up to F₉ in the selected population. Resistance levels increased gradually from generation F₁₁ to F₃₅, and elevated significantly from generations F₃₇ to F₄₅ when resistance ratios reached 1,415.3- to 2,229.9-fold at LC₅₀ and 9,613.1- to 17,062.6-fold at LC₉₀ Possible mechanisms of resistance development to spinosad were discussed.

A Culex quinquefasciatus Say colony was selected for 45 generations at LC_70–90 levels using Natular XRG, a granular formulation of 2.5% spinosad for induction of spinosad resistance. Resistance to spinosad was noticed in early generations (F₁–F₉). Resistance levels increased gradually from generations F₁₁–F₃₅, and elevated significantly from generation F₃₇ through F₄₇. when resistance ratios reached 2,845–2,907-fold at LC₅₀ and 11,948–22,928-fold at LC₉₀ The spinosad-resistant Cx. quinquefasciatus colony was found not to be cross-resistant to Bacillus thuringiensis israelensis (Bti), a combination of Bti and Bacillus sphaericus, methoprene, pyriproxyfen, diflubenzuron, novaluron, temephos, or imidacloprid. However, it showed various levels of cross-resistance to B. sphaericus, spinetoram, abamectin, and fipronil. Conversely, a laboratory colony of Cx. quinquefasciatus that is highly resistant to B. sphaericus did not show cross-resistance to spinosad and spinetoram. Field-collected and laboratory-selected Cx. quinquefasciatus that showed low to moderate resistance to methoprene did not show cross-resistance to spinosad and spinetoram. Mechanisms of cross-resistance among several biorational pesticides were discussed according to their modes of actions.

Dengue and dengue hemorrhagic fever are mosquito-borne viral diseases that coincide with the distribution of Aedes aegypti (L.), the primary vector in the tropical and semitropical world. With no available vaccine, controlling the dengue vector is essential to prevent epidemics. The effects of the insect growth regulator pyriproxyfen on Ae. aegypti adults that survived a treatment with a sublethal dose were investigated in the laboratory, including effects on their reproductive potential. Pyriproxyfen was released from a fumigant formulation at a dose causing 20 or 40% emergence inhibition (%EI). Females were dissected before and after blood feeding and the basal follicle number was counted. There were no differences between the control and treated group on the basal follicle number for both doses used. Fertility and fecundity were reduced at a concentration of EI₄₀ but no at EI₂₀. There was no ovicidal effect of pyriproxyfen by immersion of eggs in treated water neither when the females laid their eggs on a pyriproxyfen-treated surface. This work shows that sublethal doses of pyriproxyfen can have effects on fertility and fecundity of Ae. aegypti females, which together with its larvicidal activity could contribute to an overall decrease in a given population.

The residual efficacy of λ-cyhalothrin sprayed on foliage was evaluated against various mosquito species in sections of forest in Cairns, Queensland, Australia. Weekly sweep-net collections in treated and untreated areas before and after spraying showed 87–100% reductions in mosquito numbers for the first 9 wk postspray. After that period, reductions fluctuated but remained >71% up to 14 wk posttreatment. Mosquito mortality ranged from 96 to 100% in contact bioassays of treated leaves during the 14 wk study. Our results demonstrate that spraying harborage vegetation with λ-cyhalothrin is an extremely effective strategy for the control of sylvan and peridomestic mosquito species in tropical north Queensland.

The study examines the extent and frequency of a knockdown-type resistance allele (kdr type) in North American populations of human head lice. Lice were collected from 32 locations in Canada and the United States. DNA was extracted from individual lice and used to determine their zygosity using the serial invasive signal amplification technique to detect the kdr-type T917I (TI) mutation, which is most responsible for nerve insensitivity that results in the kdr phenotype and permethrin resistance. Previously sampled sites were resampled to determine if the frequency of the TI mutation was changing. The TI frequency was also reevaluated using a quantitative sequencing method on pooled DNA samples from selected sites to validate this population genotyping method. Genotyping substantiated that TI occurs at high levels in North American lice (88.4%). Overall, the TI frequency in U.S. lice was 84.4% from 1999 to 2009, increased to 99.6% from 2007 to 2009, and was 97.1% in Canadian lice in 2008. Genotyping results using the serial invasive signal amplification reaction (99.54%) and quantitative sequencing (99.45%) techniques were highly correlated. Thus, the frequencies of TI in North American head louse populations were found to be uniformly high, which may be due to the high selection pressure from the intensive and widespread use of the Pyrethrins- or pyrethroid-based pediculicides over many years, and is likely a main cause of increased pediculosis and failure of Pyrethrins- or permethrin-based products in Canada and the United States. Alternative approaches to treatment of head lice infestations are critically needed.

The effectiveness of the amides piplartine and piperlonguminine isolated from Piper species for controlling L3 and L4 of Aedes aegypti (L.) was assessed through bioassays at concentrations ranging from 1 to 300 µg/ml. Piplartine reduced the mosquito development period and caused larval mortality only at concentrations >100 µg/ml, whereas piperlonguminine resulted in an extended period of mosquito development (10 µg/ml) and caused 100% larval mortality (30 µg/ml) within 24 h. The toxicity and cytotoxic effects of piperlonguminine on epithelial cells of the digestive system of Ae. aegypti were viewed using transmission electron microscopy, which indicated vacuolization of cytoplasm, mitochondrial swelling and leaking of nuclear material. Piperlonguminine was the more effective amide, showing toxic activity with LD₅₀ of ≈12 µg/ml against the larvae of Ae. aegypti.

In total, 183,602 female culicine mosquitoes were captured by Mosquito Magnet, black light, and New Jersey light traps, and manual aspiration of resting blood-fed mosquitoes, in the Republic of Korea from 2008 to 2011. Culicine mosquitoes were identified to species, placed in pools of up to 30 mosquitoes each, and screened for flavivirus RNA by using an SYBR green I-based reverse transcription-polymerase chain reaction assay. Thirty-two of the 8,199 pools assayed were positive by quantitative polymerase chain reaction for Chaoyang virus (CHAOV), an insect-specific virus [26 Aedes vexans nipponii Theobald, 3 Culex pipiens L., 1 Aedes albopictus (Skuse), 1 Aedes bekkui Mogi, and 1 Armigeres subalbatus (Coquillett)]. The maximum likelihood estimations (estimated number of virus-positive mosquitoes/1,000 mosquitoes) for Ae. bekkui, Ae. albopictus, Ar. subalbatus, Ae. vexans nipponii, and Cx. pipiens positive for CHAOV were 5.37,3.29,0.77,0.27, and 0.26, respectively. CHAOV is an insect-specific virus, and there is currently no evidence to suggest a role in animal or human disease.

We assessed the potential for vacant lots and other nonresidential settings to serve as source environments for Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) in Mérida City, México. Mosquito immatures were collected, during November 2011–June 2013, from residential premises (n = 156 site visits) and nonresidential settings represented by vacant lots (50), parking lots (18), and streets or sidewalks (28). Collections totaled 46,025 mosquito immatures of 13 species. Ae. aegypti was the most commonly encountered species accounting for 81.0% of total immatures, followed by Culex quinquefasciatus Say (12.1%). Site visits to vacant lots (74.0%) were more likely to result in collection of Ae. aegypti immatures than residential premises (35.9%). Tires accounted for 75.5% of Ae. aegypti immatures collected from vacant lots. Our data suggest that vacant lots should be considered for inclusion in mosquito surveillance and control efforts in Mérida City, as they often are located near homes, commonly have abundant vegetation, and frequently harbor accumulations of small and large discarded water-holding containers that we now have demonstrated to serve as development sites for immature mosquitoes. In addition, we present data for associations of immature production with various container characteristics, such as storage capacity, water quality, and physical location in the environment.

A bird-parasitic fly, Carnus orientalis Maa, 1968, is recorded for the first time from Japan, and it is taxonomically reexamined on the basis of specimens collected in Okinawa Prefecture. Adult flies were found from nestlings of Ryukyu scops owl (Otus elegans Cassin, 1852), which is a new host for C. orientalis. Bionomic remarks regarding C. orientalis are presented, and a key to the world species of Carnus is also provided.