Mosquito Culex Quinquefasciatus Say Research Articles

Bioactive Potentials of Petunia Integrifolia (Hook.) Schinz & Thell. Against Culex Quinquefasciatus Larvae, Artemia Salina Nauplii and Poecilia Reticulata Adults

Petroleum ether (pet. ether), chloroform (CHCl3) and methanol (CH3OH) extracts of Petunia integrifolia (Hook.) Schinz & Thell. Whole plant was subjected to assess cytotoxicity against the brine shrimp Artemia salina L. nauplii, larvicidal activity against the mosquito Culex quinquefasciatus Say larvae and piscicidal activity against the Poecilia reticulata Peters adults. The P. integrifolia extract in pet. ether showed the highest cytotoxic activity against A. salina nauplii by giving the minimum LC50 value of 49.25 parts per million (ppm) at 48 h, while in case of CHCl3 and CH3OH extracts, the values were 63.37 and 342.55 ppm, respectively. Against C. quinquefasciatus larvae the three extracts gave LC50 values of 4.92, 5.51 and171.26 ppm, respectively all after 48 h of exposure. Against P. reticulata the LC50 values were 21.70 ppm for pet. ether extract at 48 h, and 31.91 ppm for CHCl3 extract after 42 h of exposure but CH3OH extract offered no mortality. According to the intensity of activity, therefore, the extracts could be arranged in the descending order of: pet. ether > CHCl3 > CH3OH extracts; and the sensitivity of the test organisms to the extract of P. integrifolia could be arranged in the following descending order: C. quinquefasciatus larvae (in Pet. ether; LC50 = 4.92 ppm) > P. reticulata (in pet ether; LC50 = 21.70 ppm) >A. salina nauplii (in pet. ether; LC50 = 49.25 ppm) J. Bio-Sci. 31(1): 99-108, 2023

Evaluation of field resistance in field-collected mosquito Culex quinquefasciatus Say through quantification of ULV permethrin/PBO formulation in field bioassays.

Pyrethroids are among the most applied adulticides worldwide to control mosquito vectors for prevention of arboviral diseases transmission. However, pesticide resistance development in a mosquito population could lead to decreased control efficacy. While most studies investigate the resistant genotype (i.e. kdr, CYP450, etc.) as explanatory variables, few field efficacy studies have measured pesticide quantities deposited at different distances from the sprayer in association with observed mosquito mortality. The current study determined field delivered amounts of an applied ULV permethrin/PBO formulation (31% permethrin + 66% piperonyl butoxide) by GC/MS and estimated practical resistance ratios using caged mosquito females. For field samples, the extraction method recovered 78 ± 3.92-108 ± 8.97% of the permethrin/PBO formulation when utilizing the peaks of PBO from GC/MS to estimate the concentrations of adulticide deposited near the mosquito cages. The field bioassay showed that the spatial distribution of permethrin/PBO formulation was heterogeneous among three pseudo-replicates within the same distance. Within the quantifiable permethrin/PBO range of 15.7-51.4 ng/cm2 , field-collected mosquito mortalities started at 64% and linearly increased reaching 100% only in two areas, while all Sebring susceptible mosquitoes died. The field LC95 resistance ratio (RR) of F0 Cx. quinquefasciatus ranged from 2.65-3.51, falling within the 95% CI of RR95 estimated by laboratory vial assays. Tests with and without PBO indicated P450's enzymes contributed to field resistance. Results showed the suitability of the collection and quantification method to estimate the field resistance ratio at the applied pesticide rate. Pesticide quantification would also allow the association of the known frequencies of resistance mechanisms (e.g. kdr, CYP450) with field mortalities to estimate the resistance level conferred by such mechanisms. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Comparative Efficacy of Selected Biorational Insecticides against Larvae of Southern House Mosquito Culex quinquefasciatus Say (Diptera: Culicidae)

Comparative Efficacy of Selected Biorational Insecticides against Larvae of Southern House Mosquito Culex quinquefasciatus Say (Diptera: Culicidae)

Cross Resistance in S-Methoprene-Resistant Culex quinquefasciatus (Diptera: Culicidae).

The juvenile hormone analog S-methoprene is the only synthetic biopesticide that is registered with the United States Environmental Protection Agency to control arthropods of economic importance in public health, livestock, pets, urban, and stored products. The high activity, relative target specificity, and benign environmental profile of S-methoprene have been well documented. While the risk of resistance in mosquitoes to S-methoprene is generally low, there is a lack of information regarding cross resistance in S-methoprene-resistant mosquitoes to other pesticides. In this paper, a population of the southern house mosquito Culex quinquefasciatus Say from southern California acquired low levels of resistance to S-methoprene in the field, where the resistance ratios ranged 7.0- to 8.8-fold as compared with a laboratory reference colony. After 30 generations of laboratory selections by S-methoprene when resistance was elevated to 57.4- to 168.3-fold relative to an unselected population, various levels of cross resistance to other commonly used pesticides were revealed in the selected population. Cross resistance to the microbial mosquito larvicide Lysinibacillus sphaericus (Meyer & Neide) (Bacillales: Bacillaceae) was the most profound, amounting to 77.50- to 220.50-fold. The mechanism and potential management tactics toward cross resistance are discussed to preserve the unique value of this synthetic biopesticide.

Bloodmeal Host Selection of Culex quinquefasciatus (Diptera: Culicidae) in Las Vegas, Nevada, United States.

St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) have recently emerged in the southwestern United States. Surveillance for arboviruses in Las Vegas, NV, detected a surge of SLEV activity in the southern house mosquito (Culex quinquefasciatus Say) during 2016. To identify candidate avian amplifiers, we assessed the identification, viral infection, and immune status of vertebrate hosts for 195 blood-engorged Cx. quinquefasciatus mosquitoes collected in August and September 2016. Bloodmeals were identified from 164 engorged abdomens, representing 19 species of birds and three species of mammals. No SLEV or WNV viremia was detected, but one mosquito tested positive for Culex flavivirus. House finch (Haemorhous mexicanus) (Muller) was the most common bloodmeal, followed by domestic chicken (Gallus gallus) (Linnaeus), American robin (Turdus migratorius) L., house sparrow (Passer domesticus) (L.), great-tailed grackle (Quiscalus mexicanus) (Gmelin), northern mockingbird (Mimus polyglottos) (L.) and mourning dove (Zenaida macroura) (L.). SLEV-reactive antibodies were detected in six identified bloodmeals and WNV-reactive antibodies were detected in 33. House sparrow and house finch were the most likely hosts to show previous exposure to SLEV and WNV, respectively. Over-utilization by Cx. quinquefasciatus for bloodmeal hosts was observed primarily among robin, finch and sparrow, all species that roost communally. House finch stands out as a candidate important amplifier for both SLEV and WNV because of its preference by mosquito vectors, and high competence for closely related virus strains. While implicated in previous outbreaks as an important mosquito vector, Cx. quinquefasciatus feeds infrequently on mammals in Las Vegas, indicating a low risk for bridge transmission to humans.

Morphological variation in invasive mosquito Culex quinquefasciatus Say (Diptera: Culicidae) larvae from an urban site in Auckland, New Zealand

ABSTRACTLarvae of the invasive mosquito Culex quinquefasciatus Say are morphologically similar to those of the native Culex pervigilans Bergroth, yet distinguishing these species can be hampered by morphological variations in Cx. quinquefasciatus. We present detail about the extent of these variations in an urban population of Cx. quinquefasciatus in Auckland. To aid in identification of this exotic species, we provide images of key diagnostic characters and some observed exceptions to these. Details regarding variation in diagnostic characters for < 3rd instar and 3rd/4th instar larvae are given. Of the nine characters used for identification, three were highly consistent (dorsal papillae, mantle plate, pecten teeth); each observed in > 90% of larvae, although these characters were not always visible. Other characters were less reliable, for instance, the expected position of seta 1a-S in relation to the pecten teeth was observed in < 10% of larvae. Further exploration of regional morphological variation in both Cx. quinquefasciatus and Cx. pervigilans is recommended, ideally with associated molecular characterisation.

Oviposition preference and offspring performance in container breeding mosquitoes: evaluating the effects of organic compounds and laboratory colonisation.

The preference-performance hypothesis predicts that organisms lacking parental care should oviposit in habitats that optimize offspring performance. We investigated preference-performance relationships for the Asian tiger mosquito (Aedes albopictus Skuse) and the southern house mosquito (Culex quinquefasciatus Say) (Diptera:Culicidae), two medically important container-breeding species, in response to an organic chemical blend mimicking decaying plant matter. Additionally, we evaluated the effects of long-term laboratory colonization of Cx. quinquefasciatus by using wild and laboratory strains.Oviposition bioassays were conducted by releasing gravid mosquitoes into field enclosures with automobile tires containing low and high concentrations of the chemical blend, and water controls. The offspring were then reared in water collected from the tires in which they were deposited.Aedes albopictus and wild Cx. quinquefasciatus laid more eggs in the chemical blend than water controls but did not differentiate between the low and high concentrations. Conversely, laboratory Cx. quinquefasciatus only preferred the high concentration to the low concentration. No statistical associations between oviposition preference and larval survival were found, as the chemical blend did not affect survivorship of either species.The oviposition preference for the chemical blend over water controls suggests that both species oviposit in the best available resource environment, but further studies are needed before conclusions regarding preference-performance relationships can be drawn.We found that long-term laboratory colonization affects oviposition behavior in Cx. quinquefasciatus, suggesting that behavioral studies on laboratory strains are not always applicable to wild populations.

Effect Of Toxicity Of Neem (Azadirachta Indica A. Juss) And Mohaneem (Melia Azedarach Linnaeus) On The Larvae Of Mosquito Culex Quinquefasciatus (Say) (Diptera: Culicidae)

The larvicidal activities of three solvent extracts, viz. ethanol, chloroform and water of two plants neem Azadirachta indica (A. Juss) and mohaneem Melia azedarach (Linn.) against the fourth instar larvae of mosquito Culex quinquefasciatus (Say) (Diptera: Culicidae) were studied in the laboratory at 27 ± 2 °C and 75-85% RH. No larval mortality was observed in control treatment. The larval mortalities by the ethanol extracts of A. indica at the five dose concentrations were 37.33, 64.00, 64.00, 76.00 and 97.33%, respectively; by the chloroform extracts were 24.00, 54.66, 80.00, 96.00 and 100%, respectively; by the water extracts were 32.00, 56.00, 62.66, 68.00 and 81.33%, respectively. The larval mortalities by the ethanol extracts of M. azedarach at the five dose concentrations were 29.33, 58.66, 64.00, 74.66 and 89.33%, respectively; by the chloroform extracts were 40.00, 49.33, 61.33, 73.33 and 84.00%, respectively; by the water extracts were 29.33, 58.66, 64.00, 74.66 and 89.33%, respectively. In case of A. indica, LC50, LC 90 and LC99 values for the ethanol extracts were 1.805, 3.581 and 6.261 mg/ml, respectively; for the chloroform extracts were 0.686, 1.112, and 1.648 mg/ml, respectively; and for the water extracts were 3.002, 5.584 and 9.262 mg/ml, respectively. In case of M. azedarach, LC50, LC 90 and LC99 values for the ethanol extracts were 1.949, 3.89 and 6.835 mg/ml, respectively; for the chloroform extracts were 0.695, 2.256, and 5.886 mg/ml, respectively; and for the water extracts were 3.536, 6.662 and 10.866 mg/ml, respectively.&#x0D; Asiat. Soc. Bangladesh, Sci. 42(2): 209-218, December 2016

Biological Control of &lt;I&gt;Culex quinquefasciatus&lt;/I&gt; Say (Diptera: Culicidae) Larvae

Local larvivorous fish Aphanius dispar has potential for regulating vector mosquitoes. The consumption of larvae of the mosquito Culex quinquefasciatus Say (Diptera: Culicidae) by Rasbora daniconius, Puntius ticto and Puntius conchonius was evaluated in the presence of different prey densities under simple habitat conditions. The number of mosquito larvae consumed in fresh and ditch water at three seasons was observed. Only third and fourth instars of Culex larvae were used on a particular prey density of 1 to 10 (increase 100). The maximum and minimum value of larvae eating per day in ditch and fresh water were observed to 267 to 876 and 277 to 880 respectively. The comparisons for the pair using Tukey-Kramer HSD indicated the fact that there was non-significant difference. The respective mean values in fresh and ditch water were observed 525 and 493 respectively. The analysis of water (ditch and fresh) was nonsignificant (F = 1.0116). Rasbora daniconius species of fish played a dominating role in eating the Culex larvae in ditch and fresh water.

Coticotropine-Releasing Hormone receptor 1 (CRHR1) signalling interferes with steroid biosynthesis of ovarian granulosa cells

Repellency activity of Thai essential oils derived from ylang ylang (Cananga odorata (Lamk.) Hook.f. & Thomson: Annonaceae) and lemongrass (Cymbopogon citratus (DC.) Stapf: Poaceae) were tested against two mosquito vectors, Aedes aegypti (L.) and Culex quinquefasciatus (Say). There were compared with two chemical repellents (DEET 20% w/w; Sketolene Shield® and IR3535, ethyl butylacetylaminopropionate 12.5% w/w; Johnson's Baby Clear Lotion Anti-Mosquito®). Each herbal repellent was applied in three diluents; coconut oil, soybean oil and olive oil at 0.33 μl/cm2 on the forearm of volunteers. All herbal repellent exhibited higher repellent activity than IR3535 12.5% w/w, but lower repellent activity than DEET 20% w/w. The C. odorata oil in coconut oil exhibited excellent activity with 98.9% protection from bites of A. aegypti for 88.7 ± 10.4 min. In addition, C. citratus in olive oil showed excellent activity with 98.8% protection from bites of C. quinquefasciatus for 170.0 ± 9.0 min. While, DEET 20% w/w gave protection for 155.0 ± 7.1–182.0 ± 12.2 min and 98.5% protection from bites of two mosquito species. However, all herbal repellent provided lower repellency activity (97.4–98.9% protection for 10.5–88.7 min) against A. aegypti than C. quinquefasciatus (98.3–99.2% protection for 60–170 min). Our data exhibited that C. odorata oil and C. citratus oil are suitable to be used as green repellents for mosquito control, which are safe for humans, domestic animals and environmental friendly.

Efficacy of Thai herbal essential oils as green repellent against mosquito vectors

Repellency activity of Thai essential oils derived from ylang ylang (Cananga odorata (Lamk.) Hook.f. & Thomson: Annonaceae) and lemongrass (Cymbopogon citratus (DC.) Stapf: Poaceae) were tested against two mosquito vectors, Aedes aegypti (L.) and Culex quinquefasciatus (Say). There were compared with two chemical repellents (DEET 20% w/w; Sketolene Shield® and IR3535, ethyl butylacetylaminopropionate 12.5% w/w; Johnson's Baby Clear Lotion Anti-Mosquito®). Each herbal repellent was applied in three diluents; coconut oil, soybean oil and olive oil at 0.33μl/cm2 on the forearm of volunteers. All herbal repellent exhibited higher repellent activity than IR3535 12.5% w/w, but lower repellent activity than DEET 20% w/w. The C. odorata oil in coconut oil exhibited excellent activity with 98.9% protection from bites of A. aegypti for 88.7±10.4min. In addition, C. citratus in olive oil showed excellent activity with 98.8% protection from bites of C. quinquefasciatus for 170.0±9.0min. While, DEET 20% w/w gave protection for 155.0±7.1–182.0±12.2min and 98.5% protection from bites of two mosquito species. However, all herbal repellent provided lower repellency activity (97.4–98.9% protection for 10.5–88.7min) against A. aegypti than C. quinquefasciatus (98.3–99.2% protection for 60–170min). Our data exhibited that C. odorata oil and C. citratus oil are suitable to be used as green repellents for mosquito control, which are safe for humans, domestic animals and environmental friendly.

Laboratory selection of resistance to spinosad in Culex quinquefasciatus (Diptera: Culicidae).

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 ofNatular XRG against this colony were determined in the laboratory for the first-generation progeny (designated as F1). Selection pressure was applied at LC70-90 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.

Olfactory responses of the antennal trichoid sensilla to chemical repellents in the mosquito, Culex quinquefasciatus

Insect repellents are widely used to protect against insect bites and thus prevent allergic reaction and the spread of disease. To gain insight into the mosquito’s response to chemicals repellents, we investigated the interaction between the olfactory system of the mosquito Culex quinquefasciatus Say and chemical repellents using single sensillum recording. The interactions of 50 repellent chemicals with olfactory receptor neurons were measured in six different types of mosquito sensilla: long sharp trichoid (LST), short sharp trichoid (SST), short blunt trichoid I (SBT-I), short blunt trichoid II (SBT-II), short blunt trichoid-curved (SBT-C), and grooved peg (GP). A single olfactory neuron reacted to the chemical repellents in each of the sensilla except for SBT-I and SBT-II, where two neurons were involved. Other than LST and GP, which showed no or very weak responses to the repellents tested, all the sensilla showed significant excitatory responses to certain types of repellents. Terpene-derived chemicals such as eucalyptol, α-pinene, and camphor, stimulated olfactory receptor neurons in a dose-dependent manner and mosquitoes responded more strongly to terpene-derived chemical repellents than to non-terpene-derived chemicals such as dimethyl phthalate. Mosquitoes also exhibited a similar response to stereoisomers of chemicals such as (−)-β-pinene versus (+)-β-pinene, and (−)-menthone versus (+)-menthone. This study not only demonstrates the effects of chemical repellents on the mosquito olfactory system but also provides important information that will assist those screening new mosquito repellents and designing new mosquito control agents.

Larvicidal potentiality of &lt;i&gt;Derris indica&lt;/i&gt; Bennet. extracts against &lt;i&gt;Culex quinquefasciatus&lt;/i&gt; Say (Diptera: Culicidae) larvae

Chloroform extracts of fruit shell, leaf, root-bark, root-wood, seeds, stem-bark and stem-wood of Derris indica Bennet. were tested on the mosquito Culex quinquefasciatus Say larvae. The LC50 values of fruit shell, leaf, root-bark, root-wood, seed, stem-bark and stem-wood were 30762.54, 60922.83, 70070.31, 3867.32, 361.89, 453810.10 and 225860.20 ppm, respectively for 30 minutes of exposure; 220.60, 141.56, 59.54, 36.95, 21.52, 229.92 and 82.84 ppm, respectively for 24 hours of exposure, and 49.97, 34.00, 26.26, 18.33, 8.64 , 68.88 and 30.15 ppm, respectively for 48 hours of exposure. The dose-mortality effects were in the order: seed &gt; root-wood &gt; root-bark &gt; stem-wood &gt; leaf &gt; fruit shell &gt; stem-bark. DOI: http://dx.doi.org/10.3329/bjz.v39i2.10568 Bangladesh J. Zool. 39(2): 137-145, 2011

Insecticide resistance in Culex quinquefasciatus from Zanzibar: implications for vector control programmes

BackgroundZanzibar has a long history of lymphatic filariasis (LF) caused by the filarial parasite Wuchereria bancrofti, and transmitted by the mosquito Culex quinquefasciatus Say. The LF Programme in Zanzibar has successfully implemented mass drug administration (MDA) to interrupt transmission, and is now in the elimination phase. Monitoring infections in mosquitoes, and assessing the potential role of interventions such as vector control, is important in case the disease re-emerges as a public health problem. Here, we examine Culex mosquito species from the two main islands to detect W. bancrofti infection and to determine levels of susceptibility to the insecticides used for vector control.MethodsCulex mosquitoes collected during routine catches in Vitongoji, Pemba Island, and Makadara, Unguja Island were tested for W. bancrofti infection using PCR. Insecticide bioassays on Culex mosquitoes were performed to determine susceptibility to permethrin, deltamethrin, lambda-cyhalothrin, DDT and bendiocarb. Additional synergism assays with piperonyl butoxide (PBO) were used for lambda-cyhalothrin. Pyrosequencing was used to determine the kdr genotype and sequencing of the mitochondrial cytochrome oxidase I (mtCOI) subunit performed to identify ambiguous Culex species.ResultsNone of the wild-caught Culex mosquitoes analysed were found to be positive for W. bancrofti. High frequencies of resistance to all insecticides were found in Wete, Pemba Island, whereas Culex from the nearby site of Tibirinzi (Pemba) and in Kilimani, Unguja Island remained relatively susceptible. Species identification confirmed that mosquitoes from Wete were Culex quinquefasciatus. The majority of the Culex collected from Tibirinzi and all from Kilimani could not be identified to species by molecular assays. Two alternative kdr alleles, both resulting in a L1014F substitution were detected in Cx. quinquefasciatus from Wete with no homozygote susceptible detected. Metabolic resistance to pyrethroids was also implicated by PBO synergism assays.ConclusionsResults from the xenomonitoring are encouraging for the LF programme in Zanzibar. However, the high levels of pyrethroid resistance found in the principle LF vector in Pemba Island will need to be taken into consideration if vector control is to be implemented as part of the elimination programme.

West Nile virus vector competency of Culex quinquefasciatus mosquitoes in the Galapagos Islands.

The mosquito-transmitted pathogen West Nile virus (WNV) is not yet present in the Galápagos Archipelago of Ecuador. However, concern exists for fragile endemic island fauna after population decreases in several North American bird species and pathology in certain reptiles. We examined WNV vector competency of a Galápagos strain of mosquito (Culex quinquefasciatus Say). Field specimens were tested for their capacity to transmit the WN02-1956 strain of WNV after incubation at 27°C or 30°C. Rates of infection, dissemination, and transmission all increased with days post-exposure to WNV, and the highest rates were observed at 28 days. Infection rates peaked at 59% and transmission rates peaked at 44% (of mosquitoes tested). Vector efficiency increased after day 14. Rates of infection but not of transmission were significantly influence by temperature. No vertical transmission was detectable. We demonstrate that Galápagos Cx. quinquefasciatus are competent WNV vectors, and therefore should be considered an animal and public health risk for the islands and controlled wherever possible.

A Novel Technique for Feeding and Confirming Uptake of Bacteria in Larvae of the Southern House Mosquito,Culex quinquefasciatus(Diptera: Culicidae)

Aquatic macroinvertebrates play important roles in freshwater ecosystems. The larvae of the vector mosquito Culex quinquefasciatus Say (Diptera: Culicidae) primarily reside in standing water rich in organic matter; these conditions are also suited for growth of microbial biofilms. As microbes serve as a food source for larvae, the study of interactions between microbial biofilms and C. quinquefasciatus can aid in understanding the routes by which aquatic larvae can acquire pathogens, and the role such larvae may play in environmental persistence of microorganisms. Studies in butterflies, nematodes, and ticks have described interactions with bacteria acquired by the oral route, including arthropods that play a role in dissemination of bacteria on beet plants. In pursuit of these goals, this manuscript describes a new protocol for investigating larval mosquito feeding on microbial biofilms. Fluorescent microscopy and GFP expressing bacterial strains were used to show larval acquisition and midgut localization of bacteria from both planktonic and biofilm sources. PCR testing for the GFP plasmid confirmed presence of the test strain in fed larvae. The results of microscopy and PCR assays demonstrate that Culex quinquefasciatus larvae will feed on microbial biofilms in a laboratory environment. The efficiency of studying microbial fate through common microscopic and molecular techniques, in combination with an easily maintained vector insect colony, means this approach can be used to investigate a multitude of research questions relating to microbial effects on larval physiology, fitness, and conditioning.

Transcriptome Changes in &lt;I&gt;Culex quinquefasciatus&lt;/I&gt; (Diptera: Culicidae) Salivary Glands During West Nile Virus Infection

Persistent West Nile virus (WNV) infection in the mosquito Culex quinquefasciatus Say (Diptera: Culicidae) is associated with pathological changes in the salivary glands, including apoptotic cell death and a corresponding reduction in virus transmission over time. The vector host response to WNV infection and the molecular basis of WNV pathogenesis in Cx. quinquefasciatus was investigated using oligonucleotide microarrays designed to detect differences in the salivary gland transcriptome between WNV-infected mosquitoes and uninfected controls. Transcripts with increased abundance in infected salivary glands included those related to immunity, transcription, protein transport and degradation, amino acid and nucleotide metabolism, signal transduction, and cellular detoxification. Microarray-based analysis detected a decrease in transcript levels of a Culex inhibitor of apoptosis gene (IAP-1) and a decrease in abundance of 11 transcripts encoding salivary gland proteins. Transcript levels for an endonuclease, a proline-rich mucin, and several D7 protein family members also decreased. Transcripts with the greatest change in abundance during infection had either no similarity to sequences found in GenBank, VectorBase, and FlyBase, or were similar to sequences with uncharacterized protein products. These transcripts represent exciting targets for future analysis. Results from this study suggest that WNV infection influences transcriptional changes in an invertebrate host target tissue that may confer an advantage to the replicating virus, induce a host defense response, and alter the composition of vector saliva. The ramifications of these changes are discussed in terms of mosquito vector competence and WNV pathogenesis.

Southern House Mosquito Culex quinquefasciatus Say

EENY457, a 6-page illustrated fact sheet by Stephanie Larrick and Roxanne Connelly, is part of the Featured Creatures collection. It describes this medium-sized brown mosquito that exists throughout the tropics and the lower latitudes of temperate regions and is a vector of many pathogens, several of which affect humans — synonymy, distribution, description, life cycle, medical importance, and management. Includes references. Published by the UF Department of Entomology and Nematology, November 2009. EENY457/IN837: Southern House Mosquito Culex quinquefasciatus Say (ufl.edu)

Effects of an aqueous extract of Azadirachta indica on the growth of larvae and development of pupae of Culex quinquefasciatus.

The neem tree Azadirachta indica Juss (Meliaceae) is one of the most studied plant species for pest control, including mosquitoes. However, the effect of aqueous neem seed extracts (ANSE) on each of the 4 instars of mosquito Culex quinquefasciatus Say (Diptera: Culicidae) is unknown. In order to determine the effect of applying ANSE on the growth of each of the 4 larval instars and pupal stage of C. quinquefasciatus , 8 bioassays with ANSE concentrations ranging from 30 to 1000 ppm were applied to larvae of 1st, 2nd, 3rd and 4th instars. The experimental unit consisted of a plastic cup with 100 ml of water and 20 larvae. 1 ml of the different concentrations of ANSE was applied. Mortality was assessed when 93 to 98% of the larvae reached the pupae stage in the control. In the surviving population the duration of larval stages and pupae viability were recorded. The growth of larvae and development of pupae was recorded to determine a growth inhibition index (GII) and a relative growth index (RGI), which was used to calculate the EC