Quinquefasciatus Say Research Articles

Characterization of a Strain of <i>Bacillus sphaericus</i> Isolated from Local Rice Field and its Virulence against Mosquito Larvae

Objective: Classical chemical control to mosquito is a preferable method. But it faces a problem for its increasing resistance against mosquito. To regulate the vector population as an alternative method, non-hazardous biocontrol methods would be the preeminent option to control mosquitoes. Objective of the present study is to examine the virulence of Bacillus sphaericus as an effective biocontrol agent against mosquitoes.Method: A strain of the bacteria Bacillus sphaericus was isolated from the gut of dead Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) larva collected from submerged rice fields, Burdwan, West Bengal, India. The strain was characterized following standard methodologies.Result: The bacterial strain formed crystals, tolerated 4% NaCl, produced protease and sensitive to different known antibiotics. An aqueous preparation of the bacteria revealed that 10ml/L (6.8x10 6 bacteria/ml) Bs formulation (bacterial broth) killed 100% larvae of Cx. quinquefasciatus , Anopheles subpictus, Armigeres subalbatus within 6 hours of exposure. Field tests showed that by the end of seventh day of application a total reduction of Cx. quinquefasciatus was achieved and 87% and 64% reduction of An. subpictus and Ar. subalbatus immatures were observed respectively. No larval emergence was observed up to tenth day in case of Cx. quinquefasciatus . The results indicate that the isolated strain of B. sphaericus can be a potential larvicide to regulate mosquito populations.Conclusion: Further tests need to be carried out to justify its use against different other mosquito species and insects.

The Effects of Temperature and Precipitation on Culex quinquefasciatus (Diptera: Culicidae) Abundance: A Case Study in the Greater Waco City, Texas

The southern house mosquito, Culex quinquefasciatus Say is a major mosquito vector of West Nile virus in the southern United States. The regional temperature and precipitation are key factors to the population dynamics of the mosquito Culex quinquefasciatus. The understanding of the relations between climatic conditions and Culex mosquito dynamics has an important implication for the management of WNV outbreaks in the southern United States and elsewhere. We analyzed the monthly averages of minimum and maximum temperatures, precipitation amount, and mosquito samplings in two years 2011-2012. Warm temperature along with at least above precipitation during the study period appears to have facilitated the mosquito abundance. An important finding is the potential influence of early warmer spring with relatively high rainfalls increased the WNV vector population in 2012. In addition, continuous precipitation in the summer period maintains the vector population, which appears to be a causative factor of the WNV outbreak in the region. Awareness of such two climate factors at beginning of the spring and summer may help to predict the WNV disease risk.

Comparison among Populations of Mosquitoes Culex quinquefasciatus Say by using Geometric Morphometric Technique from Different Regions of Iraq

The geometric morphometric technique was used to study the variables in the shape and size wings of different populations of mosquitoes Culex quinquefasciatus from different Iraqi provinces Babylon, Baghdad and Wasit. The results showed that the average of centroid size were 366, 387.5 and 407.4 Micron in Babylon, Baghdad and Kut, respectively. The statistical analysis showed that there were no significant differences in the average of centroid size of all specimens and they belong to the same species.

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.
 Asiat. Soc. Bangladesh, Sci. 42(2): 209-218, December 2016

Larvicidal activity of essential oil of Peumus boldus Molina and its ascaridole-enriched fraction against Culex quinquefasciatus

Culex quinquefasciatus (Say, 1823), known as the domestic mosquito, is a common and abundant species throughout the world, and a cosmopolitan species. The adults of this mosquito are important in terms of public and animal health since they display adaptability to different hosts. In humans, they are responsible for the transmission of various diseases. One manner of control of this vector is the use of insecticidal or larvicidal products, which may have the drawback of toxicity to mammals and can be harmful to the environment. The present work evaluated the larvicidal potential of the essential oil (EO) and ascaridole-enriched fraction (EF4-5) obtained from the leaves of Peumus boldus Molina (boldo). The EO, obtained by steam distillation, was analyzed by GC/MS and fractionated on silica gel. EO and EF4–5, containing 31.4% and 89.5% ascaridole, respectively, were evaluated against C. quinquefasciatus at concentrations of 100, 50 and 25 μg/ml on the third and fourth instars. They showed lethal concentrations (LC50) of 82.14 and 41.85 μg/ml, respectively. Larvae treated with the EF4-5 showed morphological changes in the midgut, with cells possessing a cytoplasm that contained small vacuole-like structures, as well as a nucleus with decondensed chromatin and a cell apex with a short brush border. The cells of the fat body showed larger protein granules, which were acidophilic relative to the larvae of the control group. Moreover, the enriched fraction at a dose of 50 μg/ml showed a residual larvicidal effect according to exposure time on C. quinquefasciatus. This residual effect deserves consideration, since a long-term larvicidal product may be a useful tool for vector control.

Comparative analysis of the circadian rhythm genes period and timeless in Culex pipiens Linnaeus, 1758 (Diptera, Culicidae).

Nucleotide sequences of the circadian rhythm genes, period and timeless, were studied for the first time in mosquitoes Culex pipiens Linnaeus, 1758. In this work we evaluated variations of the studied genome fragments for the two forms of Culex pipiens (forma “pipiens” – mosquitoes common for aboveground habitats, forma “molestus” – underground mosquitoes). We compared Culex pipiens from Russia with transatlantic Culex pipiens and subtropical Culex quinquefasciatus Say, 1823. Our results show that intraspecies variability is higher for the gene period than for the gene timeless. The revealed substitutions in nucleotide sequences and especially in amino acid sequences grouped the individuals of the two forms into distinct clusters with high significance. The detected fixed amino acid substitutions may appear essential for functioning of the circadian rhythm proteins in Culex pipiens, and may be correlated with adaptations of the taxa within the group Culex pipiens. Our results suggest that natural selection favors fixed mutations and the decrease in diversity of the genes period and timeless in mosquitoes of the Culex pipiens f. “molestus” compared with the Culex pipiens f. “pipiens”, is probably correlated with adaptive features of Culex pipiens f. “molestus”. The studied genome regions may be considered as promising molecular-genetic markers for identification, population and phylogenetic analysis of similar species and forms of the Culex pipiens complex.

Larvicidal and pediculicidal activity of synthesized TiO2 nanoparticles using Vitex negundo leaf extract against blood feeding parasites

Insecticide resistance and inadequate attention to the application instructions of topical pediculicides are common reasons for treatment failure. Essential oils or plant extracts are good and safe alternatives due to their low toxicity to mammals and easy biodegradability. The present study was carried out to establish the larvicidal and the pediculicidal activity of synthesized titanium dioxide nanoparticles (TiO2 NPs) using the leaf aqueous extract of Vitex negundo (Verbenaceae) against the fourth instar larvae of the malaria vector, Anopheles subpictus Grassi and filariasis vector, Culex quinquefasciatus Say (Diptera: Culicidae) and the head louse, Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae). The synthesized TiO2 NPs were characterized by UV, XRD, FTIR and SEM-EDX. The SEM analyses were clearly indicated that the spherical shape of the synthesized TiO2 NPs. Mosquito larvae and head lice were exposed to varying concentrations of the synthesized TiO2 NPs, V. negundo leaf aqueous extract and titanium tetrachloride (TiCl4) for 24h. The maximum activity was observed in the synthesized TiO2 NPs against A. subpictus, C. quinquefasciatus and lice, (LC50=7.52, 7.23 and 24.32mg/L; χ2=0.161, 2.678 and 4.495; r2=0.663, 0.742 and 0.924), respectively. The TiO2 NPs did not exhibit any noticeable toxicity on Poecilia reticulata after 24h of exposure. The findings revealed that the synthesized TiO2 NPs possess excellent mosquito larvicidal and anti-lice activity. These results suggest that the green synthesis of TiO2 NPs has the potential to be used as an ideal eco-friendly approach for the control of vectors and head lice.

Climate Change Influences on the Global Potential Distribution of the Mosquito Culex quinquefasciatus, Vector of West Nile Virus and Lymphatic Filariasis.

Rapid emergence of most vector-borne diseases (VBDs) may be associated with range expansion of vector populations. Culex quinquefasciatus Say 1823 is a potential vector of West Nile virus, Saint Louis encephalitis virus, and lymphatic filariasis. We estimated the potential distribution of Cx. quinquefasciatus under both current and future climate conditions. The present potential distribution of Cx. quinquefasciatus showed high suitability across low-latitude parts of the world, reflecting the current distribution of the species. Suitable conditions were identified also in narrow zones of North Africa and Western Europe. Model transfers to future conditions showed a potential distribution similar to that under present-day conditions, although with higher suitability in southern Australia. Highest stability with changing climate was between 30°S and 30°N. The areas present high agreement among diverse climate models as regards distributional potential in the future, but differed in anticipating potential for distribution in North and Central Africa, southern Asia, central USA, and southeastern Europe. Highest disparity in model predictions across representative concentration pathways (RCPs) was in Saudi Arabia and Europe. The model predictions allow anticipation of changing distributional potential of the species in coming decades.

Larvicidal efficacy of six insecticides against culex quinquefasciatus say (Diptera: culicidae) larvae

Searching for potent larvicidal toxic effects of six synthetic organophosphate insecticides (Diazinon 60 EC, Solar 55 EC, Malathion 57 EC, Delathroit 40 EC, Parathrin 10 EC and Clorasid 20 EC) were evaluated in the laboratory against 3rd or 4th instar larvae of the mosquito species, Culex quinquefasciatus Say. The tested insecticides: Diazinon (Dizinol) 60 EC, Solar (Chloropyrics 50% + Cypermethrin 5%) 55 EC, Malathion (Sithion) 57 EC, Delathroit (Dimehoate) 40 EC, Parathrin (Cypermethrin) 10 EC and Clorasid (Chloropyrics) 20 EC showed LC50 values at application dosages 0.00250-0.05 ppm, 0.0001-0.0025 ppm, 0.00025-0.005 ppm, 0.0005-0.001 ppm, 0.0001-0.002 ppm and 0.00025-0.0025 ppm to be 8.609×10-3 ppm, 4.440×10-4 ppm, 9.094×10-4 ppm, 24.215×10- 5 ppm, 4.797×10-4 ppm and 7.022×10-4 ppm respectively. Among the six insecticides, on the basis of LC50 and relative potency values, Delathroit 40 EC was the most toxic followed by Solar 40 EC > Parathrin 10 EC > Clorasid 20 EC > Malathion 57 EC > Diazinon 60 EC.J. Asiat. Soc. Bangladesh, Sci. 42(1): 13-20, June 2016

Biological Control of <I>Culex quinquefasciatus</I> 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.

Ovicidal and larvicidal activities of some plant extracts against Aedes aegypti L. and Culex quinquefasciatus Say (Diptera: Culicidae)

ObjectiveTo evaluate the ovicidal and larvicidal activities of hexane, chloroform and methanol extracts of Gymnema sylvestre, Scilla peruvina, Rubia cordifolia (R. cordifolia) and Elytraria acaulis roots against the eggs and larvae of Aedes aegypti L. (Ae. aegypti) and Culex quinquefasciatus Say (Cx. quinquefasciatus) at different concentrations of 62.5, 125, 250 and 500 mg/L. MethodsThe plant materials were shade dried in the laboratory for one week and then coarsely powdered. The root powder of each plant (500 g) was sequentially soaked in hexane, chloroform and methanol for 96 h with intermittent shaking. After 96 h, the solution was filtered and the filtrate was concentrated under reduced pressure by using rotary vacuum evaporator. All the crude extracts thus obtained were stored in air tight glass vials and Petri dishes. ResultsThe ovicidal activity results showed that the methanol extract of R. cordifolia root was the most potent compared to other with 82.40% and 70.40% activity against the eggs of Cx. quinquefasciatus and Ae. aegypti, respectively, at 500 mg/L concentration similarly, methanol extract of R. cordifolia root also recorded the highest larvicidal activity with LC50 and LC90 values of 95.69, 347.96 mg/L against Cx. quinquefasciatus and 102.23, 350.20 mg/L against Ae. aegypti larvae, respectively. ConclusionsHence, methanol extract of R. cordifolia root can be probed further for effective biological control of mosquitoes.

Entomological assessment of yellow fever-epidemic risk indices in Benue State, Nigeria, 2010–2011

Yellow fever (YF) is a vector-borne disease affecting humans and non-human primates in tropical areas. In the past, there have been pockets of YF outbreaks in Nigeria that resulted in preventable deaths. Surveillance efforts towards avoiding another outbreak have been put in place with the aim of early detection and control. However, risk indices relating to the density of immature YF-mosquito vectors are given little consideration even though it is the first step in curbing a possible outbreak. Immature collections from 1538 houses in Ega, Oju, Otukpoicho and Otukpo in Benue State were carried out in 2010 and 2011. Risk indices such as house index (HI), container index (CI) and Breteau index (BI) were estimated. Molecular detection of YF was carried out on randomly selected Aedes larvae and pupae. Overall, 431,381 mosquitoes were collected in and around house premises. Thirteen species were identified: Ae. aegypti (Linneaus), Ae. africanus (Theobald), Ae. albopictus (Skuse), Ae. cumminsii (Theobald), Ae. luteocephalus (Newstead), Ae. simpsoni s.l. (Theobald), Ae. vittatus (Bigot), Anopheles gambiae Giles, An. nili (Theobald), Cx. nebulosus Theobald, Culex quinquefasciatus Say, Lutzia tigripes (Grandpre and Charmoy) and Toxorhynchites brevipalpis Theobald. The HI, CI and BI for Ae. aegypti were high in all the study locations, but low for Ae. lueteocephalus except in Ega. With 50 immature Aedes mosquitoes screened across locations, only Ae. aegypti from Ega were positive for YF. This study places Ega on a high alert of an impending YF outbreak. Thus, urgent steps to clear this area of potential mosquito sites are highly recommended.

Insights Into the Evolution of Chemoreceptor Genes Superfamily in Tyrophagus putrescentiae (Acari: Acaridae).

All living organisms, including animals, plants, fungi, and bacteria, use the olfactory system to recognize chemicals or pheromone from their environment. Insects detect a volatile substance using odorant receptors (ORs) or gustatory receptors (GRs) and ionotropic receptors (IRs). The gene families of the olfactory system in Acari are still not clear. In this study, we identified seven ORs, one GR, and five IRs from the transcriptome of the storage mite, Tyrophagus putrescentiae Schrank. No olfactory coreceptor was found in this transcriptome. Phylogenetic analysis of these gene families with other Arthropoda species revealed the conservation of carbon dioxide receptors in all tested flying insects and T. putrescentiae Most of these ORs and GRs were unique to three mosquitoes (Anopheles gambiae Giles, Culex quinquefasciatus Say, and Aedes aegypti L.), Ixodes scapularis Say and Pediculus humanus L., indicating their involvement in specific aspects of both gustatory and olfactory perception. Some clades contained receptors obtained from all tested insect vector species, indicating a degree of conservation among some vector-dependent OR lineages. IRs family was a highly dynamic and independent original of the chemoreceptor genes subfamily. Our findings would make it possible for future research on the chemosensory recognition mechanism in Acari.

Differential protein expression in the midgut of Culex quinquefasciatus mosquitoes induced by the insecticide temephos.

Mosquitoes are vectors for pathogens of malaria, lymphatic filariasis, dengue, chikungunya, yellow fever and Japanese encephalitis. Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) is a known vector of lymphatic filariasis. Its control in Brazil has been managed using the organophosphate temephos. Studies examining the proteins of Cx. quinquefasciatus that are differentially expressed in response to temephos further understanding of the modes of action of the insecticide and may potentially identify resistance factors in the mosquito. In the present study, a comparative proteomic analysis, using 2-dimensional electrophoresis coupled with matrix-assisted laser desorption/ionization (MALDI) time of flight (TOF)/TOF mass spectrometry, and bioinformatics analyses were performed to identify midgut proteins in Cx. quinquefasciatus larvae that were differentially expressed in response to exposure to temephos relative to those in untreated controls. A total of 91 protein spots were differentially expressed; 40 were upregulated and 51 were downregulated by temephos. A total of 22 proteins, predominantly upregulated, were identified as known to play a role in the immune response, whereas the downregulated proteins were involved in energy and protein catabolism. This is the first proteome study of the midgut of Cx. quinquefasciatus and it provides insights into the molecular mechanisms of insecticide-induced responses in the mosquito.

Comparative pharmacological characterization of D1-like dopamine receptors from Anopheles gambiae, Aedes aegypti and Culex quinquefasciatus suggests pleiotropic signaling in mosquito vector lineages.

BackgroundSmall molecule antagonists of mosquito dopamine receptors (DARs) are under investigation as a new class of vector-selective insecticides. Antagonists that inhibit the D1-like DARs AaDOP2 and CqDOP2 from the mosquitoes Aedes aegypti L. and Culex quinquefasciatus Say, respectively, also cause larval mortality in bioassays. Here, we report on the orthologous DAR, AgDOP2, from the malaria mosquito Anopheles gambiae Giles that was cloned and pharmacologically characterized in HEK293 cells. Larval bioassays were then conducted to examine the potential of DAR antagonist insecticides against Anopheles vectors.FindingsPrevious in vitro cAMP accumulation assays demonstrated Gαs coupling for AaDOP2 and CqDOP2 and dose-dependent inhibition by DAR antagonists. We observed a negligible response of AgDOP2 in the cAMP assay, which prompted an investigation of alternative coupling for mosquito DARs. In an in vitro IP-One Gαq second messenger assay of calcium signaling, dopamine stimulation increased IP1 accumulation in AaDOP2-, CqDOP2- and AgDOP2-expressing cells, and DAR antagonists inhibited IP1 signaling in a dose-dependent manner. In larval bioassays, DAR antagonists caused considerable mortality of An. gambiae larvae within 24 h post-exposure.ConclusionsIn vitro data reveal pleiotropic coupling of AaDOP2 and CqDOP2 to Gαq and Gαs. In contrast, AgDOP2 appeared to selectively couple to Gαq signaling. In vitro antagonist studies revealed general conservation in pharmacology between mosquito DARs. In vivo data suggest potential for DAR antagonist insecticides against An. gambiae. Sequence conservation among the DOP2 receptors from 15 Anopheles species indicates utility of antagonists to control residual malaria transmission. AgDOP2 Gαq-dependent signaling could be exploited for An. gambiae control via pathway specific antagonists.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1477-6) contains supplementary material, which is available to authorized users.

Production of two entomopathogenic Aspergillus species and insecticidal activity against the mosquito Culex quinquefasciatus compared to Metarhizium anisopliae

ABSTRACTThe spore productivity and insecticidal activity of two opportunistic insect pathogenic Aspergillus species (namely: Aspergillus clavatus Desmazieres and Aspergillus flavus Link (Ascomycota: Eurotiales, Trichocomaceae)) were compared to Metarhizium anisopliae sensu lato (Metchnikoff) Sorokin (Ascomycota: Hypocreales, Clavicipitaceae) for mosquito (Diptera: Culicidae) control. The production of aerial spores on wheat bran and white rice was investigated in solid-, semi-solid-, and liquid-state media supplemented with a nutritive solution. Wheat bran-based media increased the spore yield in solid-state from three to sevenfold: A. clavatus produced 48.4 ± 5.2 and 15.7 ± 1.6 × 108 spores/g, A. flavus produced 22.3 ± 4.1 and 3.1 ± 2.5 × 108 spores/g, and M. anisopliae produced 39.6 ± 6.5 and 13.1 ± 2.6 × 108 spores/g of wheat bran or white rice, respectively. A. clavatus, A. flavus and M. anisopliae spores harvested from wheat bran-based solid-state media showed lethal concentrations (LC50) of 1.1, 1.8, and 1.3 × 108 spores/ml against Culex quinquefasciatus Say larvae in 72 h. Because A. clavatus and M. anisopliae displayed similar features when cultured under these conditions, our results suggest that insect pathogenic Aspergillus species may be as productive and virulent against mosquito larvae as a well-recognised entomopathogenic fungus.

Effect of ivermectin on the larvae of Anopheles gambiae and Culex quinquefasciatus.

BackgroundIvermectin is used extensively globally for treatment of helminthic and ectoparasitic infections in animals and humans. The effect of excreted ivermectin on non-target organisms in aquatic and terrestrial environments has been increasingly reported. Due to its low water solubility and adsorption to sediments, the ivermectin exposure-risk to aquatic organisms dwelling in different strata of water bodies varies. This study assessed the survival of larvae of Anopheles gambiae Giles and Culex quinquefasciatus Say, when exposed to low concentrations of ivermectin under laboratory conditions.MethodsA total of 1800 laboratory reared mosquito larvae of each species were used in the bioassays. Twelve replicates were performed, each testing 6 concentrations of ivermectin (0.0, 0.001, 0.01, 0.1, 1.0 and 10.0 parts per million (ppm)) against third instar larvae of An. gambiae and Cx. quinquefasciatus. Larval mortality was recorded at 24 and 48 h post addition of ivermectin.ResultsSurvival declined markedly with increase in ivermectin concentration in both species. While mean survival of An. gambiae at 24 h of exposure was 99.6 %, 99.2 % and 61.6 % in 0.001, 0.01 and 0.1 ppm of ivermectin, respectively, the mean survival of Cx. quinquefasciatus at the same dosage and time was 89.2 %, 47.2 % and 0.0 %. A similar pattern, but with higher mortality, was observed after 48 h of exposure. Comparison between the species revealed that Cx. quinquefasciatus larvae were significantly more affected by ivermectin than those of An. gambiae, both at 24 and 48 h.ConclusionsLow concentrations of ivermectin in the aquatic environment reduced the survival of larvae of An. gambiae and Cx. quinquefasciatus, with the effect being more marked in the latter species. It is suggested that this difference may be due to the different water strata occupied by the two species, with ivermectin adsorbed in food that sediment being more readily available to the bottom feeding Cx. quinquefasciatus than the surface feeding An. gambiae larvae.

First report of some adult mosquitoes captured by CDC gravid traps from North-Eastern Qatar

ObjectiveTo report six species of female mosquitoes caught in CDC gravid traps for the first time in Qatar. MethodsFive traps were installed in Al-Khor community, north-eastern Qatar during the outbreak season between October-November, 2010 and February-March, 2011. ResultsThe collection revealed that the adult female mosquitoes encountered in the gravid traps were: Ochlerotatus caspius (Pallas 1771), Anopheles stephensi (Liston 1901), Culex quinquefasciatus (Say 1823), Culex pipiens biotype molestus (Forskal 1775) (Cx. pipiens molestus), Culex tritaeniorhynchus (Giles 1901) and Ochlerotatus dorsalis (Meigen 1830). Except Cx. pipiens molestus, which was previously recorded, the other five species are reported for the first time in Qatar. Among the collected adult females, Cx. pipiens molestus was the most abundant (67.2%), followed by Culex quinquefasciatus (30.2%). The other species were present in small numbers. All of the recorded species have been collected as larval stages in the previous studies except for Ochlerotatus dorsalis which is collected as adult stage for the first time in the current study. ConclusionsThe collected species are of potential medical importance that threaten the north-eastern area of Qatar. A surveillance program is urgently required to generate a database of mosquito species in the area.

Evaluation of Larval Toxicity of Lantana Camara L. and Catharanthus Roseus L. against Culex Quinquefasciatus say and Aedes Aegypti L

The present study aimed to evaluate the aqueous extracts from the leaves of Catharanthus roseus L. and Lantana camara L. against filarial vector mosquito Culex quinquefasciatus Say and dengue vector Aedes aegypti L. The plant material was macerated and extracted with distilled water. The aqueous extract was tested at different concentrations of 1000, 500, 250, 125 and 62.5 ppm concentrations against I, II, III and IV instar larvae of C. quinquefasciatus and A. aegypti. The LC50 values of C. roseus against I, II, III and IV instar larvae of C. quinquefasciatus were 30.28, 38.01, 59.12 and 71.81 and against A. aegypti 26.64, 34.64, 53.10 and 72.89 ppm. The LC50 values of L. camara against I, II, III and IV instar larvae of C. quinquefasciatus were 35.48, 46.74, 67.64 and 95.51 and against A. aegypti 35.19, 38.26, 65.98 and 91.90 ppm. No mortality of was observed in control. Our results suggest that the aqueous extract of C. roseus have the potential to be used as an ecofriendly approach for the control larvae of vector mosquito C. quinquefasciatus and A. aegypti.

Phytochemical Analyses and Larvicidal Potentiality of Fruit Peel Extracts of <i>Citrus limetta</i> against Filarial Vector <i>Culex quinquefasciatus</i>

Different concentrations of crude and different solvents viz., n-hexane, ethyl acetate, and methanol fruit peel extracts of Citrus limetta Risso ( C. limetta ) were taken for investigation for larvicidal activity against Culex quinquefasciatus Say, 1823 ( Cx. quinquefasciatus ) mosquito species. Crude extract showed good larvicidal activity with very low concentrations against 1 st - 4 th instars larvae. Only 3 rd instar larvae were taken for larvicidal bioassay experiments for each solvent extract. LC 50 values of n-hexane, ethyl acetate, and methanol fruit peel extracts of C. limetta were 661.27, 1268, and 939.43 ppm respectively after 24 h of exposure. No mortality was observed on control treatments. Log probit analyses, regression equations, and R 2 values of larvicidal bioassay experiments with crude and different solvent extracts were determined. Statistical justification was done through ANOVA analyses. Qualitative phytochemical analyses were carried out and detected different secondary metabolites. No mortality was observed on tested non target organisms.