Immune response can be negatively affected by resource limitation, so it is expected that organisms evolve strategies to minimize the impact of this environmental outcome. Phenotypic plasticity in immune response could represent a genetic response to face such situations. We investigated the effects of high and low quality and quantity of food at the larval stage on two important immune components, phenoloxidase activity (PO) and nitric oxide production (NO) measured in adults of the Dengue vector, Aedes aegypti. We reared families to determine the magnitude and pattern of expression of genetic variance, environmental variance and genotype-by-environment interaction (GEI). In addition, we quantified whether there were differences in plastic immune responses in both sexes. Our results indicated additive variance for PO and NO, but rearing environment did not produce differences among individuals. For NO and PO in males, there were large differences among families in plasticity, as indicated by the different slopes produced by each reaction norm. Therefore, there is additive genetic variation in plasticity for NO production and PO activity. One possible interpretation of these results is that different genotypes may be favored to fight pathogens under the different food quality situations. Males and females showed similar overall GEI strategies but there were differences in PO and NO. Males showed a phenotypic correlation between PO and NO, but we did not find genetic correlations between immune parameters in both sexes.

We reanalyzed a dataset consisting of ≈10,700 crepuscular and night-biting female mosquitoes (Culicidae) collected over 12 mo in the canopy and understorey of primary Amazonian rain forest. We investigate whether vertical habitat stratification and rainfall modified major ecological parameters of this mosquito ensemble, combining descriptive and hypothesis-testing statistics with species richness and diversity metrics in the analyses. A total of 31 species was recorded. Contrary to expectations, the host-seeking mosquito fauna was less diverse in the forest canopy than in the understorey. In particular, species diversity and evenness were higher in understorey samples, whereas species richness estimates were similar in both habitats. Only two out of 12 species tested for vertical stratification were clearly acrodendrophilic, and five preferred understorey habitats. The mosquito fauna was more diverse in the rainy than in the dry season. We propose the hypothesis that female mosquito density and host defensive behavior may promote host seeking in nonpreferred habitats by acrodendrophilic mosquito species. These results may be particularly relevant for understanding the dynamics of Plasmodium malariae/brasilianum and arboviral infections in Amazonian forested landscapes.

Despite numerous ecological studies with mosquitoes, it remains unclear what environmental factors are the most important determinants of structure, species richness, and abundance of mosquito assemblages. In the current study, we investigated relations between these characteristics of mosquito larvae assemblages and environmental factors in a large set of different habitats. Particular objectives were (1) to rank the factors regarding their explanatory power, and (2) to quantify the contribution of major sets of factors such as habitat spatial/hydrological (H), water physico-chemical (W), and aquatic vegetation characteristics (V). Variance partitioning and forward selection based on ordinations and multiple regressions were applied to the data set on 79 water-bodies in southwestern Siberia covering a wide gradient of environmental characteristics and diverse mosquito assemblages. The results showed that richness and abundance inter-correlated poorly (r² = 0.21), and assemblage structure, richness, and abundance depended on different sets of predictors. Explanatory importance of the three sets of environmental factors differed among the three assemblage variables: H, W, and V had equal importance for assemblage structure, while richness and abundance depended on H and V more than on W. The study showed that contradiction between the aims of conservation (support biodiversity) and mosquito control (reduce mosquito abundance) can be avoided, as relevant environmental factors can be used to define habitats with high richness and low abundance (i.e., high conservation value and low nuisance and disease transmission risk) for conservation activities, and conversely for control measures.

Analyses of the dorsal abdominal glands of fourth- and fifth-instar nymphs of the bed bud, Cimex lectularius L. (Hemiptera: Cimicidae), indicated the predominant constituents were (E)-2-hexenal and (E)-2-octenal, with lesser amounts of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal. The latter two compounds have not been reported previously as occurring in bed bugs. There were no differences in the chemical composition of the dorsal abdominal glands excised from exuviae left behind by either male or female adults, nor from glands excised from fourth-instar exuviae. Because the two oxo-aldehydes made up at least 16% of the gland contents, further study of the functional role of these chemicals seem advisable.

Studies were conducted to examine the population genetic structure of Anopheles arabiensis (Patton) in Mwea Rice Irrigation Scheme and surrounding areas in Central Kenya, under different agricultural systems. This study was motivated by observed differences in malaria transmission indices of An. arabiensis within the scheme compared with adjacent nonirrigated areas. Agricultural practices can modify local microclimate and influence the number and diversity of larval habitats and in so doing may occasion subpopulation differentiation. Thirty samples from each of the three study sites were genotyped at eight microsatellite loci. Seven microsatellite loci showed high polymorphism but revealed no genetic differentiation (FST = 0.006, P = 0.312) and high gene flow (Nm = 29–101) among the three populations. Genetic bottleneck analysis showed no indication of excess heterozygosity in any of the populations. There was high frequency of rare alleles, suggesting that An. arabiensis in the study area has a high potential of responding to selective pressures from environmental changes and vector control efforts. These findings imply that An. arabiensis in the study area occurs as a single, continuous panmictic population with great ability to adapt to human-imposed selective pressures.

Lone star ticks, Amblyomma americanum L. (Acari: Ixodidae), infest multiple hosts such as birds, and mammals of various sizes (rodents to white-tailed deer) and can harbor human pathogens such as Borrelia lonestari and Ehrlichiosis chaffeensis. The population structure of 251 A. americanum ticks, collected from canines and two white-tailed deer in six Arkansas ecoregions, was examined using DNA sequences of a 247-bp region of the mitochondrial DNA ribosomal RNA 16S gene. Of the 247 nucleotide characters, 26 were variable. Thirty-three haplotypes were identified of which 25 haplotypes occurred once (10%). The most common haplotype was Aa25, occurring in 60% of the samples and found in all six ecoregions. The excess of low frequency haplotypes combined with the overall negative Tajima's D and Fu and Li statistics suggests population expansion. Phylogenetic relationships of the 33 A. americanum haplotypes were constructed with other Amblyomma species and identified A. americanum as a monophyletic species with two groups. The patterns of high nucleotide and haplotype diversity found in this study suggests that the A. americanum population is expanding perhaps due to its ability to survive in a variety of habitats and feed on multiple hosts. Given the gene flow in Arkansas, the spread of acaricide resistance and pathogens may be rapid.

Glutathione transferases (GSTs) (E.C.2.5.1.18) are multifunctional enzymes involved in the detoxification of many exogenous and endogenous compounds. This study aimed to characterize several new GSTs from Anopheles cracens, a major Thai malaria vector formerly known as Anopheles dirus. The three recombinant enzymes obtained were from the epsilon, theta and omega classes. They showed 80–93% identity to orthologous An. gambiae GSTs. AcGSTE2-2 possessed peroxidase activity that cannot be detected for the An. gambiae AgGSTE2-2. AcGSTT1-1 had high activity toward several substrates that are specific for mammalian theta class. The AcGSTO1-1 can use 1-chloro-2,4-dinitrobenzene, dichloroacetic acid, and hydroxyethyl disulfide substrates. The enzymes bound but did not metabolize the organophosphate temephos. The epsilon AcGSTE2-2 functioned as a peroxidase and DDT metabolizing enzyme. The theta AcGSTT1-1 functioned not only as peroxidase but also acted as a binding protein for organophosphates. The omega GST had thiol transferase activity suggesting a role in oxidative stress response.

Aedes aegypti L. is the primary vector of dengue and yellow fever viruses, and use of aerosolized insecticides is one of the primary ways to control this medically important mosquito. However, few new insecticides have been developed for mosquito control in recent years. As a part of our effort to search for new insecticides to control mosquitoes, toxicities of 33 carboxamides were evaluated against female A. aegypti by topical application. This group included nine different categories of compounds, namely benzamides, phenyl-propenamides, propanamides, butanamides, butenamides, pentanamides, pentenamides, hexanamides, and hexenamides, that exhibited varying levels of toxicity against this mosquito species. The most toxic compound tested was hexahydro-1-(1-oxohexyl)-1H-azepine, with a 24-h LD₅₀ value of 0.4 µg per mosquito, whereas the most toxic compound at the LD₉₅ level was N-ethyl-2-methyl-N-phenyl-benzamide (1.82 µg per mosquito). The least toxic compound was N,N-bis (2-methylpropyl)-3-phenyl-2-propenamide, with LD₅₀ and LD₉₅ values of 15.66 and 72.07 µg per mosquito, respectively. Results from this initial study may prove useful in guiding further carboxamide modifications for the development of potential new insecticides.

Wolbachia is a maternally inherited endosymbiont inducing various effects in insects and other invertebrate hosts that facilitate the invasion of naïve host populations. One of the effects is a form of sterility known as cytoplasmic incompatibility (CI) through which females are effectively sterilized when they mate with males harboring a different Wolbachia strain. The repeated mass release of cytoplasmically incompatible males can be a tool to suppress insect populations. Here, we attempt to infect an Aedes albopictus (Skuse) (Diptera: Culicidae) strain, artificially deprived of the natural Wolbachia infection, with a new Wolbachia strain from Culex pipiens (L.) (Diptera: Culicidae). Further experiments were designed to study the effects of the new infection on Ae. albopictus fitness and evaluate key parameters that affect infection dynamics, including CI level and maternal inheritance. Using embryonic microinjection, the new Wolbachia strain was successfully established in Ae. albopictus. Crosses demonstrated a pattern of bidirectional CI between naturally infected and transinfected individuals. Specifically, egg hatch was essentially absent (i.e., CI was very high) in all crosses between the transinfected males and females with a different infection status. Furthermore, naturally infected Ae. albopictus males were incompatible with the transinfected females. Maternal inheritance was close to 100%. Moreover, the new infection did not affect immature and adult survivorship, but it significantly reduced female fecundity and egg hatch rate. The results are discussed in relation to the potential use of the new Ae. albopictus—Wolbachia symbiotic association as a suitable system for the study and development of CI-based strategies for suppressing populations of this important pest and disease vector.

Insecticide resistance in populations of mosquitoes is an escalating problem that can directly affect disease prevalence. Determining the fitness associated with an insecticide resistance mechanism (allele) will provide for greater understanding of the evolution of resistance, and help inform effective vector management programs. Previously, a population cage experiment in which the alleles of two highly related strains of Culex pipiens quinquefasciatus (Say) SLAB (susceptible) and ISOP450 (permethrin resistant because of cytochrome P450-mediated detoxification) were placed in direct competition in the absence of insecticide revealed that the P450 resistance allele frequency decreased over time. In the current study, SLAB and ISOP450 development, mortality and energetic resources derived from glycogen, other sugars and lipids were measured to identify biological parameters that might explain the previously observed fitness cost. SLAB exhibited shorter egg-to-adult female development time and larger body size when reared in groups when compared with ISOP450. ISOP450 female adults provided 20% sugar water lived longer than 20% sugar water fed females of the SLAB strain. No significant differences in larval development time, larval mortality, pupal stage duration time, pupal mortality, longevity of male and female adults provided with distilled water and males provided sugar water were found between the strains. The caloric content from glycogen and lipids were significantly higher in SLAB relative to ISOP450 in adults. The slower female emergence time and smaller body size when reared in groups combined with lower energy reserves (glycogen and lipids) associated with the resistance allele (in ISOP450) are likely fitness costs associated with the resistance allele of P450-mediated detoxification.

Compounds thought to be effective against mosquitoes as either ‘insecticides’ or ‘repellents’ have recently been shown to contain properties of both, or possess other behaviormodifying actions. Prompted in part by these reports, we conducted posterior analyses of our data to examine some interrelated statistical issues inherent in our bioassay system. Using a modified K&D module, the responses of over 25,000 adult Aedes aegypti (L.) females exposed to either alphacypermethrin or DEET were compared with the responses of mosquitoes exposed to untreated controls for toxicity and biting (alphacypermethrin) or biting alone (DEET). Our analyses indicated that; (1) our bioassay system has more statistical power to determine a compound's toxicity than its repellent qualities, (2) day-to-day variability is large and needs to be accommodated in analyses; there are other, potentially even larger sources of variability (e.g., mosquito heterogeneity) which invalidate statistical tests that are based on the assumption of binomially or multinomially distributed data (e.g., χ2 tests), and (3) unlike biting mosquitoes exposed to DEET, the proportions of biting mosquitoes exposed to alphacypermethrin are unrelated to the proportions of concurrently tested biting controls, even after adjusting for daily variation in toxicity. Thus, there is a clear behavioral indicator in this bioassay system that the ‘repellency’ of DEET (a presumed repellent) differs in a fundamental way from that of alphacypermethrin (a presumed toxicant), which may allow the differentiation between classes of compounds based on biting behavior alone.

Experiments were conducted to evaluate novaluron as a feed-through larvicide to control immature phlebotomine sand flies (Phlebotomus papatasi Scopoli) (Diptera: Psychodidae). The minimum effective concentration of novaluron against sand fly larvae fed hamster feces treated with novaluron, or feces of hamsters fed a diet containing novaluron, was 9.88 and 9.88 × 10^-1 mg/kg, respectively. Feces of novaluron-treated hamsters were held under conditions simulating the inside of a rodent burrow for up to 30 d, and all larvae that consumed these feces died before pupation; a significant reduction in treated larval survival relative to control was observed when the feces were aged for up to 150 d. Novaluron was shown to be effective as a feed-though larvicide when novalurontreated food made up only a portion of the diet of hamsters. The results of this study suggest that novaluron could be effective as a rodent feed-through insecticide in a field setting.

The heritability of the ability to cause paralysis was examined in crosses of virulent and avirulent Dermacentor andersoni (Stiles) (Acari: Ixodidae). Virulence was assessed using hamster bioassay. Paralysis was caused by the virulent parental strain but not by the avirulent parental strain. Four crosses were made: Avirulent ♀ X Avirulent ♂ (AA cross), Virulent ♀ X Virulent ♂ (VV cross), Avirulent ♀ X Virulent ♂ (AV cross), and Virulent ♀ X Avirulent ♂ (VA cross). The proportion of females that produced fertile egg masses was similar among the crosses; however, VV females produced fewer fertile eggs. This was attributed to the long-term laboratory colonization of the virulent strain. All crosses had similar levels of larval and nymphal engorgement and adult eclosion. The ability to cause paralysis was detected in progeny of all crosses except the AA cross. Both heterogeneous crosses caused paralysis, but the virulence was slightly less than for the VV cross. Virulence was similar among the AV and VA crosses, indicating that virulent males were as likely as females to pass the trait to progeny. Time to paralysis was faster for the VV cross compared with the heterogeneous crosses.

Differential host cell responses to the alphavirus Sindbis were observed in visceral muscles of the adult female mosquito Aedes albopictus. Following intrathoracic inoculation with SIN, muscles associated with the midgut, hindgut, and ovary resulted in clearance, persistence, and refractoriness to virus, respectively. Prominent sarcomeres characteristic of myofilaments were identified in muscles associated with these three organs by phalloidin labeling of actin, confirming these cells as muscle. The location of virus antigen mimicked the distribution of actin in both mid- and hindgut-associated muscles. Furthermore, these myofilaments remained intact following virus clearance from midgut muscles and during virus persistence in hindgut muscles. Changes in the temporal onset of virus antigen following high titer inoculum compared with standard titer inoculum was observed in anterior midgut muscles, but not in muscles associated with the posterior midgut or hindgut. Muscle bundles closely approximated the gut surface, while a wispy association was displayed at the ovary surface. Prominent ultrastructural differences were observed in the basal lamina attached to the gut compared with the ovary. Additionally, ultrastructural evidence for virus-associated pathology was observed in gut-associated muscles and gut epithelium. Visceral muscles, all composed of the same tissue type, but associated to three different organs in the insect abdomen, responded differentially to Sindbis. We speculate that variations in structure, function or physiology and ultrastructure inherent to insect host cells or organs interactions reflect the complicated milieu of the organism and contribute to differential virus phenotypic expression in muscle cells.

We collected blood-fed, snow-melt mosquitoes (Culicidae: Culiseta and Aedes) to describe the feeding patterns of potential mosquito vectors of Jamestown Canyon virus (JCV, Bunyaviridae: Orthobunyavirus). JCV is an arthropod-borne, zoonotic virus with deer as the primary amplifying host in western alpine ecosystems. We collected mosquitoes from natural resting areas, fiber pots, and carbon-dioxide baited miniature light traps in the Colorado Rocky Mountains in 2007. We conducted two polymerase chain reactions to amplify and sequence vertebrate DNA extracted from blood-fed mosquitoes, which yielded comparable, but not identical, results. Mammal-specific primers found mule deer (Odocoileus hemionus) and elk (Cervus elaphus canadensis) as the source of all bloodmeals. To determine if unamplified bloodmeals were from nonmammalian sources, we screened all samples with conserved vertebrate primers, which confirmed the initial polymerase chain reaction results, but also found porcupine (Erethizon dorsatum) and human (Homo sapiens) as additional bloodmeal sources. We consistently found that mule deer were the primary hosts for mosquitoes in this system. These results suggest that snow-melt mosquitoes, in particular A. cataphylla, may be important vectors in western JCV alpine systems and may also act as a bridge vector for JCV from cervid virus reservoirs to humans.

Culex tarsalis Coquillett, Cx. quinquefasciatus Say, and Cx. pipiens L. were collected during the warm winter of 2009 using dry ice-baited and gravid traps and walk-in red boxes positioned in desert, urban, and agricultural habitats in Riverside, Los Angeles, Kern, and Yolo Counties. Temperatures exceeded the preceding 50 yr averages in all locations for most of January, whereas rainfall was absent or below average. Abundance of Culex species in traps during January ranged from 83 to 671% of the prior 5 yr average in all locations. Few females collected resting were in diapause during January based on follicular measurements. Evidence for early season gonotrophic activity included the detection of freshly bloodied, gravid, and parous females in resting collections, gravid oviposition site-seeking females in gravid female traps, and nulliparous and parous host-seeking females at dry ice-baited traps. Female Culex seemed to employ multiple overwintering strategies in California, including larval and adult quiescence, adult female diapause, and an intermediate situation with adult females collected with enlarged follicles, but without evident vitellogenesis. West Nile, St. Louis, or western equine encephalitis viruses were not detected in 198 pools of adults or 56 pools of adults reared from field-collected immatures collected during January and February 2009. Our preliminary data may provide insight into how climate change may extend the mosquito season in California.

Host feeding patterns were examined for four species of Culex mosquitoes collected from 18 sites in or adjacent to East Baton Rouge Parish, LA, from November 2002 to October 2004. Host DNA from 37 bloodied Culex coronator Dyar and Knab, 67 bloodfed Cx. salinarius Coquillett, 112 bloodfed Cx. nigripalpus Theobald, and 684 bloodfed Cx. quinquefasciatus Say were identified. The percentages of bloodmeals containing mammalian DNA were 94.6% for Cx. coronator, 82.1% for Cx. salinarius, 66.1% for Cx. nigripalpus, and 40.1% for Cx. quinquefasciatus. Human DNA was detected in 7% of the bloodmeals from Cx. quinquefasciatus and 2.7% of the bloodmeals from Cx. nigripalpus. The northern cardinal was the most frequent avian host of Cx. quinquefasciatus and Cx. nigripalpus. In 2003 and 2004, there was no significant relationship from May through October between the proportion of Cx. quinquefasciatus feeding on mammalian hosts and the date of collection. Of the six avian species most frequently fed on by Cx. quinquefasciatus, the northern cardinal, northern mockingbird, common grackle, and brown thrasher were fed on more frequently than expected based on their abundance. House sparrows were fed on less frequently than expected based on their abundance. These data support the conclusions of previous studies that Cx. quinquefasciatus is the most important vector for both the enzootic amplification and transmission of West Nile virus to humans in southern Louisiana.

α-Mangostin derived from mangosteen was identified as a mosquito sterol carrier protein-2 inhibitor via high throughput insecticide screening. α-Mangostin was tested for its larvicidal activity against third instar larvae of six mosquito species, and the median lethal concentration values range from 0.84 to 2.90 ppm. The residual larvicidal activity of α-mangostin was examined under semifield conditions. The results indicated that α-mangostin was photolytic with a half-life of 53 min in water under full sunlight exposure. The effect of α-mangostin on activities of major detoxification enzymes such as P450, glutathione S-transferase, and esterase was investigated. The results showed that α-mangostin significantly elevated activities of P450 and glutathione S-transferase in larvae, whereas it suppressed esterase activity. Toxicity of α-mangostin against young rats was studied, and there was no detectable adverse effect at dosages as high as 80 mg/kg. This is the first multifaceted study of the biological activity of α-mangostin in mosquitoes. The results suggest that α-mangostin may be a lead compound for the development of a new organically based mosquito larvicide.

The lone star tick, Amblyomma americanum (Acari: Ixodidae), is commonly reported from people and animals throughout the eastern U.S. and is associated with transmission of a number of emerging diseases. To better define the microbial communities within lone star ticks, 16S rRNA gene based analysis using bacteria-wide primers, followed by sequencing of individual clones (n = 449) was used to identify the most common bacterial operational taxonomic units (OTUs) present within colony-reared and wild A. americanum. The colony-reared ticks contained primarily sequence affiliated with members of the genus Coxiella (89%; 81/91), common endosymbionts of ticks, and Brevibacterium (11%; 10/ 91). Similarly, analysis of clones from unfed wild lone star ticks revealed that 96.7% (89/92) of all the OTUs identified were affiliated with Coxiella-like endosymbionts, as compared with only 5.1–11.7% (5/98–9/77) of those identified from wild lone star ticks after feeding. In contrast, the proportion of OTUs identified as Rickettsia sp. in wild-caught ticks increased from 2.2% (2/92) before feeding to as high as 46.8% (36/77) after feeding, and all Rickettsia spp. sequences recovered were most similar to those described from the spotted fever group Rickettsia, specifically R. amblyommii and R. massiliae. Additional characterization of the Rickettsiales tick community by polymerase chain reaction, cloning, and sequencing of 17 kDa and gltA genes confirmed these initial findings and suggested that novel Rickettsia spp. are likely present in these ticks. These data provide insight into the overall, as well as the rickettsial community of wild lone star ticks and may ultimately aid in identification of novel pathogens transmitted by A. americanum.

In November 2004, bluetongue virus (family Reoviridae, genus Orbivirus, BTV) serotype 1 (BTV-1) was detected for the first time in the United States from a hunter-killed deer in St. Mary Parish, LA. In 2005, sera surveys were conducted on three cattle farms near the area where the deer was found, and BTV-1-seropositive cattle were found on two of the three farms; in 2006, sera surveys from the cattle on the three farms did not detect any BTV-1-positive animals. The purpose of this study was to survey ceratopogonid populations at the three farms and test field-collected specimens for the presence of BTV and epizootic hemorrhagic disease virus (family Reoviridae, genus Orbivirus, EHDV). Miniature CDC light traps and New Jersey traps were used to capture ceratopogonids on the three farms from January 2006 through November 2007. In total, 3,319 ceratopogonids were captured, including 1,790 specimens of 10 different species of Culicoides. IR-RT-polymerase chain reaction (PCR) was performed to screen for BTV and EHDV in 264 pools representing 2,309 specimens collected at the farms. All positive samples were sequenced for serotype determination. Five pools of 275 (1.8%) were positive for BTV. Pools of four species of Culicoides were found to be positive: Culicoides crepuscularis (Malloch), Culicoides debilipalpis Lutz (two pools), Culicoides haematopotus Malloch, and Culicoides furens (Poey). The amplicons of the positive specimens were sequenced and found to be identical to both BTV-17 and BTV-13. During our study, no BTV-1 transmission was detected in cattle, and no BTV-1 was detected in specimens of ceratopogonids.

Synthetic versions of human derived kairomones can be used as baits when trapping host seeking mosquitoes. The effectiveness of these lures depends not only on their attractiveness to the mosquitoes but also on the medium from which they are dispensed. We report on the development and evaluation of nylon strips as a method of dispensing odorants attractive to the malaria vector, Anopheles gambiae s.s. (Giles). When a synthetic blend of attractants was dispensed using this method, significantly more mosquitoes were trapped than when two previous methods, open glass vials or low density polyethylene sachets were used. We conclude that the nylon strips are suitable for dispensing odorants in mosquito trapping operations and can be adopted for use in rural and remote areas. The nylon material required is cheap and widely available and the strips can be prepared without specialized equipment or electricity.

The current control of Phebotomus argentipes (Annandale and Brunetti), the vector of Leishmania donovani (Laveran and Mesnil), on the Indian subcontinent is base on indoor residual spraying. The efficacy of this method depends, among other factors, on the timing and number of spraying rounds, which depend on the P. argentipes seasonality. To describe P. argentipes' seasonal patterns, six visceral leishmaniasis (VL) endemic villages, three in Muzaffarpur and three in Sunsari districts in India and Nepal, respectively, were selected based on accessibility and VL incidence. Ten houses per cluster with the highest P. argentipes density were monitored monthly for 15–16 mo using Center for Disease Control and Prevention light traps. Minimum and maximum temperature and rainfall data for the months January 2006 through December 2007 were collected from the nearest available weather stations. Backwards stepwise regression was used to generate the minimal adequate model for explaining the monthly variation in P. argentipes populations. The seasonality of P. argentipes is similar in India and Nepal, with two annual density peaks around May and October. Monthly P. argentipes density is positively associated with temperature and negatively associated with rainfall in both study sites. The multivariate climate model explained 57% of the monthly vectorial abundance. Vector control programs against P. argentipes (i.e., indoor residual spraying) should take into account the seasonal described here when implementing and monitoring interventions. Monitoring simple meteorological variables (i.e., temperature, rainfall) may allow prediction of VL epidemics on the Indian subcontinent.

Interaction of aquatic stages of coexisting mosquito species may have significant influence on resulting adult mosquito populations. We used two coexisting species, Anopheles gambiae s.s. and Culex quinquefasciatus to investigate whether third instars of one species consumed first instars of the other. First instars of one species were readily consumed by a third instar of the other species irrespective food quantity. DNA of Cx. quinquefasciatus was detected in the eight An. gambiae s.s. third instars presumed to have consumed at least one Cx. quinquefasciatus first instar. Likewise, DNA of An. gambiae s.s. was detected in five of eight Cx. quinquefasciatus third instars presumed to have consumed at least one An. gambiae s.s. first instar. A small number of dead first instars was found in the controls indicating that some larvae in the treatment group may have been consumed after they had died. These findings suggest that intraguild predation between the two species may be common in nature and that it is a facultative process that is not induced by food shortage. The findings further suggest that polymerase chain reaction could be a useful technique in the study of this phenomenon in natural habitats.