Mosquito Culex Quinquefasciatus Research Articles

Molecular and functional characterization of three novel carboxylesterases in the detoxification of permethrin in the mosquito, Culex quinquefasciatus.

Carboxylesterases (CarEs) belong to a super family of multifunctional enzymes associated with the degradation of endogenous and exogenous compounds. Many insect CarEs are known to play important roles in catalyzing the hydrolysis of organophosphates (OPs), carbamates, and synthetic pyrethroids (SPs). The elevation of esterase activity through gene amplification and overexpression of estα2 and estβ2 genes contributes to the development of resistance to OP insecticides in the mosquito Culex quinquefasciatus. Three additional CarE genes are upregulated in permethrin-resistant Cx. quinquefasciatus according to an RNA-seq analysis, but their function remains unknown. In this study, we, for the first time, characterized the function of these three novel genes using in vitro protein expression, an insecticide metabolism study and molecular docking analysis. All three CarE genes were significantly overexpressed in resistant mosquito larvae, but not adults, compared to susceptible strain. No gene copy differences in these three genes were found in the mosquitoes tested. In vitro high-performance liquid chromatography (HPLC) revealed that CPIJ018231, CPIJ018232, and CPIJ018233 metabolized 30.4% ± 2.9%, 34.7% ± 6.8%, and 23.2% ± 2.2% of the permethrin, respectively. No mutations in resistant strains might significantly affect their CarE hydrolysis ability. A docking analysis further confirmed that these three CarEs from resistant strain all potentially metabolize permethrin. Taken together, these three carboxylesterase genes could play important roles in the development of permethrin resistance in Cx. quinquefasciatus larvae through transcriptional overexpression, metabolism, and detoxification.

Studies on biochemical and synergistic effects of immunosuppressive concentration of imidacloprid with Beauveria bassiana and Metarhizium anisopliae for enhancement of virulence against vector mosquito Culex quinquefasciatus

In order to increase the virulence of two commonly used entomopathogens namely Beauveria bassiana and Metarhizium anisopliae for effective mosquito control programs, we developed new combined formulation by the use of immunosuppressive concentration of imidacloprid. Exposure of sublethal concentration (LC10 1.34 ppb) of imidacloprid to second instar larvae for 92 h that differently modulated the larval biochemical markers by decreasing the total protein (20.65% reduction), acetylcholinesterase (35.74% reduction) and increases the β-carboxylesterase (26.59% increase) and acid phosphatase (30.69% increase) levels while no significant difference was noticed in alkaline phosphatase of C. quinquefasciatus. Further we demonstrated that the imidacloprid exposure brings about reduction in phenoloxidase level (39.48% decrease) and nitric oxide production (37.64% decrease) in larval homogenate over control. The reduction in viability of hemocytes (15.37% decrease) and phagocytic activity of hemocytes (32.18% decrease) was noticed in imidacloprid treatment. Moreover in laboratory condition, exposure of 1 × 107 spores/ml of B. bassiana (984) and M. anisopliae (6060) alone for 92 h cumulative toxicity assay exhibited larval mortality of 36.47% and 47.64% respectively against C. quinquefasciatus. However in the synergistic experimental studies with LC10 of imidacloprid and 1 × 107 spores/ml of B. bassiana or M. anisopliae to the larvae for 92 h cumulative assay brought 60% and 50.59% more insecticidal activity than the respective entomopathogens alone. The substantial increase of larvicidal activity noticed in the synergistic test conditions against larvae of C. quinquefasciatus revealed that the inclusion of sublethal concentration was proved to be useful for effective larval control.

Behavioural response of mosquito vectors Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus to synthetic pyrethroid and organophosphorus-based slow-release insecticidal paint

BackgroundThe direct toxicological impact of insecticides on vector mosquitoes has been well emphasized; however, behavioural responses such as excito-repellency and physical avoidance as a result of insecticide exposure have not been much studied. We have demonstrated the excito-repellency and behavioural avoidance in certain vector mosquito species on exposure to a slow-release insecticidal paint (SRIP) formulation in addition to direct toxicity.MethodsA SRIP formulation developed by the Defence Research and Development Establishment, Gwalior, contains chlorpyriphos, deltamethrin and pyriproxyfen as active insecticides. Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti mosquitoes were used to study the excito-repellency response of the formulation. The experiments were performed in a specially designed dual-choice exposure and escape chamber made of transparent polymethyl methacrylate. For the experiments, the SRIP formulation was applied undiluted at a rate of 8 m2 per kg on 15 cm2 metallic surfaces. Mosquitoes were introduced into the exposure chamber, and observations of the movement of mosquitoes into the escape chamber through the exit portal were taken at 1-min intervals for up to 30 min.ResultsThe evaluated formulation displayed strong excito-repellency against all three tested vector mosquito species. Results showed that the ET50 (escape time 50%) for Ae. aegypti, An. stephensi and Cx. quinquefasciatus was 20.9 min, 14.5 min and 17.9 min for contact exposure (CE) respectively. Altogether in CE, the escape rates were stronger in An. stephensi mosquitoes at different time intervals compared to Ae. aegypti and Cx. quinquefasciatus mosquitoes. The probit analysis revealed that the determined ET did not deviate from linearity for both non-contact exposure (NCE) and placebo exposure (PE) (χ2 ≤ 7.9; p = 1.0) for Ae. aegypti mosquitoes and for NCE (χ2 = 8.3; p = 1.0) and PE (χ2 = 1.7; p = 1.0) treatments in Cx. quinquefasciatus. Mortality (24 h) was found to be statistically higher (F = 6.4; p = 0.02) in An. stephensi for CE but did not vary for NCE (p ≥ 0.3) and PE (p = 0.6) treatments among the tested mosquito species. Survival probability response suggested that all the three tested species displayed similar survival responses for similar exposures (χ2 ≤ 2.3; p ≥ 0.1).ConclusionThe study demonstrates the toxicity and strong behavioural avoidance in known vector mosquito species on exposure to an insecticide-based paint formulation. The combination of insecticides in the present formulation will broaden the overall impact spectrum for protecting users from mosquito bites. The efficacy data generated in the study provide crucial information on the effectiveness of the tested formulation and could be useful in reducing the transmission intensity and disease risk in endemic countries.Graphical

Bio efficacy of Cinnamaldehyde from <em>Cinnamomum verum</em> essential oil against <em>Culex quinquefasciatus</em> (Diptera: Culicidae)

This research aims to study the efficacy of Cinnamomum verum (Cv) extracts for ovicidal, larvicidal, and repellent activities against Culex quinquefasciatus mosquito vectors. The active components of C. verum or cinnamon oil by Gas Chromatography (GC) analysis showed the highest cinnamaldehyde at 83.53%. For ovicidal assay, C. verum essential oil at concentrations 12.5, 25 and 50 ppm at 72 h had 100% egg hatch inhibition and had a significant difference when compared to the control group (p<0.05). Larvicidal activity showed that concentrations of 25 and 50 ppm were highly effective in killing 100% mosquito larvae. Morphological changes in egg raft showed a faded color and eggs that seemed to have split from their raft while the larvae changed to a pale white wrinkled body with a destroyed inner tube of the body and were motionless. A Scanning electron microscope study showed that the eggshell and micropyle were wrinkled with the chitin peeled out. After treatment with cinnamon oil, larvae appeared to have a wrinkled body, the thorax and abdominal cuticle were also destroyed with high density of oil particles observed on mouth brushes and obstructing the spiracle. The repellent assay showed that cinnamon oil could repel both male and female mosquitos for up to 180 min. From the results, it was concluded that cinnamon oil had highly effective repellency against Culex quinquefasciatus adults and insecticidal activity on eggs and larvae stages evidenced by LC50 at 6.59±0.54, 9.07±0.67 and 36.91±7.56 ppm and its morphological changes indicated how the mosquito could not survive after cinnamon oil treatment hence this may be a useful alternative method that is green friendly for controlling mosquitoes in endemic areas.

Efficacy of Some Selected Indigenous Plant Extracts against Two Urban Mosquitoes Culex quinquefasciatus Say and Aedes aegypti L. (Diptera: Culicidea): An Update

Efficacies of the chloroform and aqueous extracts of the leaf, stem and root of three indigenous plants viz. Calotropis procera, Polygonum hydropiper and Thevetia neriifolia against the larval mortality and reproductive potential of two urban mosquitoes Culex quinquefasciatus Say and Aedes aegypti L. are reported here. Results show that the chloroform extracts of C. procera leaf (LC50 = 167.48 ppm), P. hydropiper stem (LC50 = 341.79 ppm) and T. neriifolia leaf (LC50 = 209.45 ppm) had excellent larvicidal effect on Cx. quinquefasciatus. The aqueous extracts of C. procera stem (LC50 = 207.18 ppm), P. hydropiper stem (LC50 = 634.92 ppm) and T. neriifolia leaf (LC50 = 453.34 ppm), however, had relatively milder larvicidal effect on the mosquitoes under study. Both the extracts significantly reduced percentage of egg-hatch and adult emergence per raft, lengthened immature duration and increased immature mortality in all the treatment groups. The chloroform extracts had a significantly negative effect on the number of eggs per raft, but both chloroform and aqueous extracts failed to induce any appreciable effect on the female ratio. Compared to the aqueous extracts, chloroform extracts are much more efficient against Cx. quinquefasciatus productivity. Results on Ae. aegypti indicated that the leaf extracts of C. procera (LC50 =696.14 ppm), the stem extract of P. hydropiper (LC50 =1164.36 ppm), and the leaf extract of T. neriifolia (LC50 =872.91 ppm) had significant larvicidal effects compared to the respective controls. In general, the extracts significantly reduced egg-laying, decreased egg-hatch, lengthened immature duration, and increased immature mortality culminating in reduced adult emergence. A comparison of the larvicidal efficacy of the extracts against the two mosquito species reveals that Cx. quinquefasciatus is more sensitive to the plant extracts than Ae. aegypti. However, further research is solicited to evaluate the impact, persistence and effectiveness of these extracts against the vector mosquitoes under indoor and field conditions.

Multiple cytochrome P450 genes: conferring high levels of permethrin resistance in mosquitoes, Culex quinquefasciatus

Insecticides, especially pyrethroids, are the most important in the insect pest control and preventing insect vector-borne human diseases. However, insect pests, including mosquitoes, have developed resistance in the insecticides that used against them. Cytochrome P450s are associated with insecticide resistance through overexpression and detoxification mechanisms in insect species. In this study, we utilized a powerful tool, the RNAi technique, to determine the roles of key P450 genes overexpressed in permethrin resistant mosquitoes that confer insecticide resistance to unravel the molecular basis of resistance mechanisms in the mosquito Culex quinquefasciatus. The results showed that knockdown of 8 key P450 genes using RNAi techniques significantly decreased resistance to permethrin in resistant mosquitoes. In silico modeling and docking analysis further revealed the potential metabolic function of overexpressed P450 genes in the development of insecticide resistance in mosquitoes. These findings not only highlighted the functional importance of these P450 genes in insecticide resistance, but also revealed that overexpression of multiple P450 genes was responsible for the high levels of insecticide resistance in a mosquito population of Culex quinquefasciatus.

Evaluation of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus Mosquitoes Competence to Oropouche virus Infection.

The emergence of new human viral pathogens and re-emergence of several diseases are of particular concern in the last decades. Oropouche orthobunyavirus (OROV) is an arbovirus endemic to South and Central America tropical regions, responsible to several epidemic events in the last decades. There is little information regarding the ability of OROV to be transmitted by urban/peri-urban mosquitoes, which has limited the predictability of the emergence of permanent urban transmission cycles. Here, we evaluated the ability of OROV to infect, replicate, and be transmitted by three anthropophilic and urban species of mosquitoes, Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus. We show that OROV is able to infect and efficiently replicate when systemically injected in all three species tested, but not when orally ingested. Moreover, we find that, once OROV replication has occurred in the mosquito body, all three species were able to transmit the virus to immunocompromised mice during blood feeding. These data provide evidence that OROV is restricted by the midgut barrier of three major urban mosquito species, but, if this restriction is overcome, could be efficiently transmitted to vertebrate hosts. This poses a great risk for the emergence of permanent urban cycles and geographic expansion of OROV to other continents.

Effect of Some Plants Extracts on the Mortality of the 4th Larval Instar Mosquitoes Culex quinquefasciatus

In this study, the effect of water and alcoholic (ethanol) extracts of Caper Bush Capparis spinosa L., Cumine Cuminum cyminum L. , Black pepper Piper nigrum L., Sage Salvia sp. and Cat thyme Teucrium polium L. plants on the 4th instar larvae of Culex quinquefasciatus have been evaluated .The results showed that the water extract of P. nigrum had the highest effect on the larvae, with 48h LC50 155. 9 ppm followed by ethanol extracts of C. cyminum , C. spinosa and P. nigrum with 48h LC50 308.2 ,315.1and 791.4 ppm respectively. For all studied plants, the secondary compounds were identified. Alkaloids and phenol extracts from Capparis spinosa, Alkaloids, flavonoids and volatile oils from Cuminum cyminum and Alkaloids and volatile oils from Piper nigrum had been isolated. The volatile oils and alkaloids extracts of P. nigrum showed the highest effect with 48h LC50 values 6.3 and 10.2 ppm, respectively then the volatile oil extract and alkaloids extract of C. cyminum with 48h LC50 were 21.1 and 429.4 ppm respectively

Susceptibility of Midge and Mosquito Vectors to SARS-CoV-2.

SARS-CoV-2 is a recently emerged, highly contagious virus and the cause of the current COVID-19 pandemic. It is a zoonotic virus, although its animal origin is not clear yet. Person-to-person transmission occurs by inhalation of infected droplets and aerosols, or by direct contact with contaminated fomites. Arthropods transmit numerous viral, parasitic, and bacterial diseases; however, the potential role of arthropods in SARS-CoV-2 transmission is not fully understood. Thus far, a few studies have demonstrated that SARS-CoV-2 replication is not supported in cells from certain insect species nor in certain species of mosquitoes after intrathoracic inoculation. In this study, we expanded the work of SARS-CoV-2 susceptibility to biting insects after ingesting a SARS-CoV-2-infected bloodmeal. Species tested included Culicoides sonorensis (Wirth & Jones) (Diptera: Ceratopogonidae) biting midges, as well as Culex tarsalis (Coquillett) and Culex quinquefasciatus (Say) mosquitoes (Diptera: Culicidae), all known biological vectors for numerous RNA viruses. Arthropods were allowed to feed on SARS-CoV-2-spiked blood and at a time point postinfection analyzed for the presence of viral RNA and infectious virus. Additionally, cell lines derived from C. sonorensis (W8a), Aedes aegypti (Linnaeus) (Diptera: Culicidae) (C6/36), Cx. quinquefasciatus (HSU), and Cx. tarsalis (CxTrR2) were tested for SARS-CoV-2 susceptibility. Our results indicate that none of the biting insects, nor the insect cell lines evaluated support SARS-CoV-2 replication, suggesting that these species are unable to be biological vectors of SARS-CoV-2.

Green catalyst Cu(II)-enzyme-mediated eco-friendly synthesis of 2-pyrimidinamines as potential larvicides against Culex quinquefasciatus mosquito and toxicity investigation against non-target aquatic species

Novel one-pot multicomponent synthesis of 2-pyrimidinamine derivatives can be achieved via green chemistry, using Cu(II)-tyrosinase enzyme (Cu-Tyr) as a catalyst. This method offers mild reaction conditions and a high yield of derivatives. We synthesised several compounds in this manner and evaluated their larvicidal, and antifeedant activities. Out of the synthesised derivatives, compound 3, with a median lethal dose (LD50) of 21.43 µg/mL, was highly active against Culex quinquefasciatus, compared to compounds 1a–m and 2, and the control, hydantocidin. Compounds 1j, 1d, and 1e were low active against C. quinquefasciatus with LD50 values of 78.46, 78.59, and 79.54 µg/mL, respectively. In antifeedant screening, compounds 1j, 1l, and 2 generated 100% mortality within 24 h against Oreochromis mossambicus at 100 µg/mL, where toxicity was determined as the ratio of the number of dead and live fingerlings (%) at 24 h. In contrast, compounds 1a–f, 1i, 1m, and 3 were less toxic to O. mossambicus as compared to the control, dibromoisophakellin. Therefore, compound 3 had high larvicidal activity against C. quinquefasciatus and was less toxic to non-target aquatic species. Molecular docking studies also supported the finding that compound 3 was an effective larvicide with more inhibition ability than the control hydantocidin (−9.6 vs. −6.1 kcal/mol).

COMPARATIVE EFFICACY OF FIVE PERMETHRIN/ PBO 30-30 GROUND ULV INSECTICIDES AGAINST FIELD COLLECTED ADULT AEDES AEGYPTI, AEDES TAENIORHYNCHUS, AND CULEX QUINQUEFASCIATUS IN MANATEE COUNTY, FLORIDA

We investigated five formulations containing synergized permethrin/PBO active ingredients, Biomist® 30-30, Evoluer® 30-30, Kontrol™ 30-30, Permanone® 30-30, and Perm-X™ UL 30-30, to determine whether there was variation in efficacy against caged local field collected adult Aedes aegypti, Aedes taeniorhynchus, and Culex quinquefasciatus mosquitoes. Mortality data from field trials with these formulations applied via truck mounted ultra-low volume sprays at mid (113 mL/ha [1.55 oz/A]) and maximum (226 mL/ha [3.10 oz/A]) label rates indicated generally low efficacy against Ae. aegypti and Cx. quinquefasciatus but generally high efficacy against Ae. taeniorhynchus. We discuss potential underlying mechanisms for this variation including effects of meteorology and resistance, and how field-derived efficacy data may be used operationally by mosquito and vector control districts to mitigate cost, environmental impact, and pesticide resistance.

Culex quinquefasciatus carrying Wolbachia is less susceptible to entomopathogenic bacteria

In an attempt to evaluate the susceptibility of the mosquito Culex quinquefasciatus to bacterial agents, a population naturally infected with a Wolbachia pipientis wPipSJ native strain was tested against the action of three bacterial mosquitocides, Bacillus thuringiensis subsp. israelensis, Bacillus wiedmannii biovar thuringiensis and Lysinibacillus sphaericus. Tests were carried out on mosquito larvae with and without Wolbachia (controls). Cx. quinquefasciatus naturally infected with the native wPipSJ strain proved to be more resistant to the pathogenic action of the three mosquitocidal bacterial strains. Additionally, wPipSJ was fully characterised using metagenome-assembled genomics, PCR–RFLP (PCR-Restriction Fragment Length Polymorphism) and MLST (MultiLocus Sequence Typing) analyses. This Wolbachia strain wPipSJ belongs to haplotype I, group wPip-III and supergroup B, clustering with other mosquito wPip strains, such as wPip PEL, wPip JHB, wPip Mol, and wAlbB; showing the southernmost distribution in America. The cytoplasmic incompatibility phenotype of this strain was revealed via crosses between wildtype (Wolbachia+) and antibiotic treated mosquito populations. The results of the tests with the bacterial agents suggest that Cx. quinquefasciatus naturally infected with wPipSJ is less susceptible to the pathogenic action of mosquitocidal bacterial strains when compared with the antibiotic-treated mosquito isoline, and is more susceptible to B. thuringiensis subsp. israelensis than to the other two mosquitocidal agents.

Role of Anopheles stephensi Mosquitoes in Malaria Outbreak, Djibouti, 2019.

Anopheles stephensi mosquitoes share urban breeding sites with Aedes aegypti and Culex quinquefasciatus mosquitoes in the Republic of Djibouti. We present evidence that A. stephensi mosquitoes might be responsible for an increase in malaria incidence in this country. We also document resistance of Plasmodium falciparum to dihydroartemisinin/piperaquine.

Identification and characterisation of mosquitoes from different locations in Qatar in 2017-2019.

Mosquito-borne infections have considerable consequences for public health. The mere presence of a single case of vector-borne disease (VBD) introduces a risk to the local community particularly when associated with the compatible vector, host, and suitable environmental factors. Presently, there is no well-established vector control and surveillance programme in Qatar; therefore, the likelihood of VBDs spreading is undetermined. As a result, there is a pressing need to address this gap and enable successful management of VBDs. This study presents the results of three consecutive field surveys conducted between 2017 and 2019 with the aim of defining the types and distribution of mosquitoes that are of public health importance in Qatar. The results of the adult mosquito trappings show that the southern house mosquito Culex quinquefasciatus is the most widespread and abundant mosquito species, followed by Cx. perexiguus, both species representing a risk of West Nile virus transmission. All sampling methods show that the malaria vector Anopheles stephensi is widespread including in urbanised areas, suggesting a risk of local malaria transmission. The wetland mosquito Aedes caspius is also widespread, representing a risk of Rift Valley fever virus transmission. The dengue vector Ae. aegypti was not detected and can be considered neither widespread nor abundant, suggesting a minimal risk for local transmission of dengue, chikungunya and Zika viruses. Interestingly, the study detected Culiseta longiareolata for the first time in Qatar. Regular field studies are needed to further address the knowledge gaps in terms of distribution, ecology, and biting habits of different mosquito species currently present in Qatar to accurately assess the risk of mosquito-borne diseases.

Investigation of bovine ephemeral fever virus transmission by putative dipteran vectors under experimental conditions

BackgroundBovine ephemeral fever virus (Rhabdoviridae: Ephemerovirus) (BEFV) causes bovine ephemeral fever (BEF), an economically important disease of cattle and water buffalo. Outbreaks of BEF in Africa, Australia, Asia and the Middle East are characterized by high rates of morbidity and highly efficient transmission between cattle hosts. Despite this, the vectors of BEFV remain poorly defined.MethodsColony lines of biting midges (Culicoides sonorensis) and mosquitoes (Aedes aegypti, Culex pipiens and Culex quinquefasciatus) were infected with a strain of BEFV originating from Israel by feeding on blood–virus suspensions and by intrathoracic inoculation. In addition, in vivo transmission of BEFV was also assessed by allowing C. sonorensis inoculated by the intrathoracic route to feed on male 6 month-old Holstein-Friesian calves.ResultsThere was no evidence of BEFV replication within mosquitoes fed on blood/virus suspensions for mosquitoes of any species tested for each of the three colony lines. In 170 C. sonorensis fed on the blood/virus suspension, BEFV RNA was detected in the bodies of 13 individuals and in the heads of two individuals, indicative of fully disseminated infections and an oral susceptibility rate of 1.2%. BEFV RNA replication was further demonstrated in all C. sonorensis that were inoculated by the intrathoracic route with virus after 5, 6 or 7 days post-infection. Despite this, transmission of BEFV could not be demonstrated when infected C. sonorensis were allowed to feed on calves.ConclusionsNo evidence for infection or dissemination of BEFV (bovine/Israel/2005-6) in mosquitoes of three different species was found. Evidence was found for infection of C. sonorensis by the oral route. However, attempts to transmit BEFV to calves from infected C. sonorensis failed. These results highlight the challenge of defining the natural vector of BEFV and of establishing an in vivo transmission model. The results are discussed with reference to the translation of laboratory-based studies to inference of vector competence in the field.Graphical abstract

UJI EFEKTIFITAS BIOLARVASIDA EKSTRAK ETANOL BUAH LAMPESU (Baccaurea lanceolata) TERHADAP LARVA INSTAR III Culex quinquefasciatus

Filariasis is chronic infection disease caused by worm and carried by Culex quinquefasciatus mosquito. One of theways to controlling mosquitoes vectors are use biolarvacide or chemical insecticide. Chemical insecticide causingresistance Culex quinquefasciatus larvae and toxic for human. This research aim to determine the biolarvacideeffectiviteness of ethanol extract lampesu fruit (Baccaurea lanceolata) to Culex quinquefasciatus larvae instars III.This study was true experimental with a Post test-only control group design. This study used 700 larvae instars III ofCulex quinquefasciatus divided into 7 groups consentration of 0,2%, 0,4%, 0,6%, 0,8% and 1%, the positive control(abate) and negative control (aquadest). The observation was did after treatment in 3 hours, 6 hours, 12 hours and 24hours. The experiment is replicated four times. At 24 hours exposure concentration of 0,6% the test larvae mortalityreached 38% and at concentration of 1% the test larvae mortality reached 30%. In this stuy the concentration of1,531 % was effective to kill larvae with of 50% mortality(LC50) and concentration of 10,729 % was effective to killlarvae with of 90% mortality(LC90). Ethanol Ekstract of Lampesu Fruit (Baccaurea lanceolata) not effective asbiolarvacide ofCulex quinquefasciatus larvae instars III.

Larvicidal activity of some selected medicinal plant extracts against the vector of filariasis

The present study assessed the role of larvicidal activities of hexane, ethyl acetate and methanol dried leaf and bark extracts of Ocimum gratissimum, Gleditsia triacanthos, Eucalyptus sglobulus and Azadirachta aindica against the fourth instar larvae of filariasis vector, Culex quinquefasciatus mosquito (Diptera: Culicidae). Larvicidal activities of four medicinal plant extracts were studied in the range of 4.69 to 1000 mg/l in the laboratory bioassays against early 4th instar larvae of Culex quinquefasciatus. The mortality data were subjected to probit analysis to determine the lethal concentrations (LC50 and LC90) to kill 50 and 90 per cent of the treated larvae of the respective species. All plant extracts showed moderate effects after 24 h of exposure; however, the highest toxic effect of leaf methanol extract of Ocimum gratissimum, bark ethyl acetate extract of Eucalyptus globulus, methanol extract of Azadirachta indicia and methanol bark extract of Gleditsia triacanthos against the larvae of Culex quinquefasciatus with LC50=43.00, 41.02, 40.12 and 20.36 mg/l; LC90=278.32, 218.72, 215.01 and 86.29 mg/l respectively. The result of findings shows that leaf and bark extract of G. tricantha, A .indica, O. gratissimum and E .globulus can be developed as ecofriendly larvicides.

Horizon Scanning to Predict and Prioritize Invasive Alien Species With the Potential to Threaten Human Health and Economies on Cyprus

Invasive Alien Species (IAS) are known to be a major threat to biodiversity and ecosystem function and there is increasing evidence of their impacts on human health and economies globally. We undertook horizon scanning using expert-elicitation to predict arrivals of IAS that could have adverse human health or economic impacts on the island of Cyprus. Three hundred and twenty five IAS comprising 89 plants, 37 freshwater animals, 61 terrestrial invertebrates, 93 terrestrial vertebrates, and 45 marine species, were assessed during a two-day workshop involving thirty-nine participants to derive two ranked lists: (1) IAS with potential human health impacts (20 species ranked within two bands:1-10 species or 11-20 species); and, (2) IAS with potential economic impacts (50 species ranked in three bands of 1-10, 11-20 and 21-50). Five species of mosquitoes (Aedes aegypti, Aedes albopictus, Aedes flavopictus, Aedes japonicus and Culex quinquefasciatus) were considered a potential threat to both human health and economies. It was evident that the IAS identified through this process could potentially arrive through many pathways (25 and 23 pathways were noted for the top 20 IAS on the human health and economic impact lists respectively). The Convention on Biological Diversity Level II (subcategory) pathways Contaminant on plants, pet / aquarium / terrarium species (including live food for such species), hitchhikers in or on aeroplanes, hitchhikers in or on ship / boats, and vehicles were the main pathways that arose across both lists. We discuss the potential of horizon scanning lists to inform biosecurity policies and communication around IAS, highlighting the importance of increasing understanding amongst all stakeholders, including the public, to reduce the risks associated with predicted IAS arrivals.

Larvicidal potential of different chromatographic fractions of the n-hexane extract of Artemisia scoparia against the vector mosquito Culex quinquefasciatus

The present study aims to explore the larvicidal activity of n-hexane extract isolated fractions from Artemisia scoparia against third instar larvae of Culex quinquefasciatus mosquito. Twelve fractions, F1 to F12 were separated through column chromatography by using different eluent solvents such as hexane, hexane-chloroform, chloroform and chloroform-methanol, in the order of increasing polarity. Larval bioassay was done by using WHO standard guideline. Larvicidal potential of the separated fractions was evaluated at tested concentrations of 30, 60, 90 and 120 ppm. Mortality rate was scored 24 h post exposure. The fractions F3 and F4 were found more active, exhibiting LC50 values of 28.66 and 22.37 ppm and LC90 values of 53.59 and 53.16 ppm respectively. The larvicidal activity of different fractions was compared by using ANOVA analysis.

Quantifying species traits related to oviposition behavior and offspring survival in two important disease vectors.

Animals with complex life cycles have traits related to oviposition and juvenile survival that can respond to environmental factors in similar or dissimilar ways. We examined the preference-performance hypothesis (PPH), which states that females lacking parental care select juvenile habitats that maximize fitness, for two ubiquitous mosquito species, Aedes albopictus and Culex quinquefasciatus. Specifically, we examined if environmental factors known to affect larval abundance patterns in the field played a role in the PPH for these species. We first identified important environmental factors from a field survey that predicted larvae across different spatial scales. We then performed two experiments, the first testing the independent responses of oviposition and larval survival to these environmental factors, followed by a combined experiment where initial oviposition decisions were allowed to affect larval life history measures. We used path analysis for this last experiment to determine important links among factors in explaining egg numbers, larval mass, development time, and survival. For separate trials, Aedes albopictus displayed congruence between oviposition and larval survival, however C. quinquefasciatus did not. For the combined experiment path analysis suggested neither species completely fit predictions of the PPH, with density dependent effects of initial egg number on juvenile performance in A. albopictus. For these species the consequences of female oviposition choices on larval performance do not appear to fit expectations of the PPH.