Attraction Of Mosquitoes Research Articles

Plasmodium falciparum gametocyte-induced volatiles enhance attraction of Anopheles mosquitoes in the field

BackgroundPlasmodium parasites manipulate the interaction between their mosquito and human hosts. Patients infected with gametocytes attract anopheline mosquitoes differentially compared to healthy individuals, an effect associated with an increased release of attractive volatile cues. This odour-driven manipulation is partly mediated by the gametocyte-specific metabolite, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), which induces increased release of select aldehydes and terpenes from red blood cells and results in the enhanced attraction of host-seeking mosquitoes, which are vectors of malaria. This study investigates the effect of the HMBPP-induced volatiles on the attraction of wild Anopheles mosquitoes to humans under field conditions.MethodsThe efficacy of the HMBPP-induced odour blend to attract Anopheles was evaluated in a 4 × 6 Latin rectangular study design indoors using baited Suna traps. Furthermore, to assess the efficacy of the HMBPP-induced odour blend in (1) augmenting the attractiveness of human odour, and (2) attracting Anopheles mosquitoes in the absence of human odour, a two-choice assay using host decoy traps (HDTs) was used and evaluated using binomial generalized regression.ResultsTraps baited with the HMBPP-induced odour blend attracted and caught both Anopheles arabiensis and Anopheles pharoensis females in a dose-dependent manner in the presence of background human odour, up to 2.5 times that of an unbaited trap. Given a choice between human odour and human odour laden with the HMBPP-induced odour blend, mosquitoes differentially preferred traps augmented with the HMBPP-induced odour blend, which caught twice as many female An. arabiensis. Traps baited with the HMBPP-induced odour blend but lacking the background of human odour were not effective in attracting and catching mosquitoes.ConclusionThe findings of the present study revealed that the HMBPP-induced odour blend, when augmented with human body odour, is attractive to anopheline mosquitoes and could be used as a complementary vector control tool along with existing strategies.

Bioassay studies on the reaction of Aedes aegypti & Aedes albopictus (Diptera: Culicidae) on different attractants.

BackgroundThe studies on mosquito attractants had been develop intensively in the recent years. However, the study on fruit peel extract as mosquito attractant was scarce, even though various fruits had demonstrated the ability to attract different types of mosquito species.ObjectiveThis study aims to determine the potential of Carica papaya (papaya) and Ananas comosus (pineapple) peel extracts to attract Aedes albopictus and Aedes aegypti.MethodsThe Aedes mosquitoes response to the fruit peel extracts were conducted in the no-choice and choice assay using modified olfactometer. The Preference Index (PI) in each assay was calculated and arcsine transformed before conducting independent t–test to determine the significant different between the mean arcsine transformed PI and the tested hypothesis mean PI.ResultNo choice assay indicate both Aedes species have significant attraction to the papaya and pineapple peel extracts (p < 0.05). In choice assay, Ae. albopictus is revealed to equally attracted to the papaya and pineapple peel extracts (p > 0.05) while Ae. aegypti is significantly attracted to the papaya peel extract (p < 0.05).ConclusionThe study had identified that both fruit peel extracts able to attract Aedes mosquitoes with Ae. albopictus is equally attracted to papaya and pineapple peel extracts while Ae. aegypti is more attracted to the papaya peel extract than the pineapple peel extract.

Insect repellents mediate species-specific olfactory behaviours in mosquitoes

BackgroundThe species-specific mode of action for DEET and many other mosquito repellents is often unclear. Confusion may arise for many reasons. First, the response of a single mosquito species is often used to represent all mosquito species. Second, behavioural studies usually test the effect of repellents on mosquito attraction towards human odorants, rather than their direct repulsive effect on mosquitoes. Third, the mosquito sensory neuron responses towards repellents are often not directly examined.MethodsA close proximity response assay was used to test the direct repulsive effect of six mosquito repellents on Anopheles coluzzii, Aedes aegypti and Culex quinquefasciatus mosquitoes. Additionally, the behavioural assay and calcium imaging recordings of antennae were used to test the response of An. coluzzii mosquitoes towards two human odorants (1-octen-3-ol and benzaldehyde) at different concentrations, and mixtures of the repellents lemongrass oil and p-menthane-3,8-diol (PMD) with DEET.ResultsAnopheles coluzzii mosquitoes were repelled by lemongrass oil and PMD, while Ae. aegypti and Cx. quinquefasciatus mosquitoes were repelled by lemongrass oil, PMD, eugenol, and DEET. In addition, high concentrations of 1-octen-3-ol and benzaldehyde were repellent, and activated more olfactory receptor neurons on the An. coluzzii antennae than lower concentrations. Finally, changes in olfactory responses to repellent mixtures reflected changes in repulsive behaviours.ConclusionsThe findings described here suggest that different species of mosquitoes have different behavioural responses to repellents. The data further suggest that high-odour concentrations may recruit repellent-sensing neurons, or generally excite many olfactory neurons, yielding repellent behavioural responses. Finally, DEET can decrease the neuronal and behavioural response of An. coluzzii mosquitoes towards PMD but not towards lemongrass oil. Overall, these studies can help inform mosquito repellent choice by species, guide decisions on effective repellent blends, and could ultimately identify the olfactory neurons and receptors in mosquitoes that mediate repellency.

Efficacy of Active Ingredients From the EPA 25(B) List in Reducing Attraction of Aedes aegypti (Diptera: Culicidae) to Humans.

Mosquitoes of the Aedes genus are vectors for dengue, chikungunya, Zika, and yellow fever viruses. Mosquito repellents are an effective way to prevent mosquito bites and reduce the spread of mosquito-borne diseases. In the early 90s, the U.S. Environmental Protection Agency (EPA) published a list of active ingredients that pose minimum risk to human health that can be used as pesticides or repellents without passing the EPA registration process. The present study examined the efficacy of 21 of the active ingredients listed by the EPA 25 (B) exempt list and five commercially available sprays that only contained active ingredients from the EPA 25(B) list in repelling female Aedes aegypti (L.) females. We performed choice bioassays in a controlled laboratory environment, using a Y-tube olfactometer to determine attraction rates of humans to female Ae. aegypti in the presence of one of the 21 active ingredients and five commercially available repellent sprays. We found that cinnamon oil, peppermint oil, spearmint oil, lemongrass oil, and garlic oil reduced mosquito attraction to human odor. Of the five commercial repellent sprays, only one reduced mosquito attraction for up to 30 min in our assay. The EPA 25 (B) list contains active ingredients that under the conditions of our assay repel Ae. aegypti.

A Population Dynamics Model of Mosquito-Borne Disease Transmission, Focusing on Mosquitoes’ Biased Distribution and Mosquito Repellent Use

We present an improved mathematical model of population dynamics of mosquito-borne disease transmission. Our model considers the effect of mosquito repellent use and the mosquito's behavior or attraction to the infected human, which cause mosquitoes' biased distribution around the human population. Our analysis of the model clearly shows the existence of thresholds for mosquito repellent efficacy and its utilization rate in the human population with respect to the elimination of mosquito-borne diseases. Further, theresults imply that the suppression of mosquito-borne diseases becomes more difficult when the mosquitoes' distribution is biased to a greater extent around thehuman population.

Human Odour Coding in the Yellow Fever Mosquito, Aedes aegypti

Insects use their olfactory systems to obtain chemical information on mating partners, oviposition sites and food. The yellow fever mosquito Aedes aegypti, an important vector of human infectious diseases, shows strong preference for human blood meals. This study investigated the chemical basis of host detection by characterizing the neuronal responses of antennal olfactory sensilla of female Ae. aegypti to 103 compounds from human skin emanations. The effect of blood feeding on the responses of olfactory sensilla to these odorants was examined as well. Sensilla SBTII, GP, and three functional subtypes of SST (SST1, SST2, and SST3) responded to most of the compounds tested. Olfactory receptor neurons (ORNs) ‘A’ and ‘B’ in the trichoid sensilla, either activated or inhibited, were involved in the odour coding process. Compounds from different chemical classes elicited responses with different temporal structures and different response patterns across the olfactory sensilla. Except for their increased responses to several odorants, blood-fed mosquitoes generally evoked reduced responses to specific aldehydes, alcohols, aliphatics/aromatics, ketones, and amines through the SST1, SST2, SBTI, SBTII and GP sensilla. The odorants eliciting diminished responses in female mosquitoes after blood feeding may be important in Ae. aegypti host-seeking activity and thus can be candidates for mosquito attractants in the process of this disease vector management.

DEET and other repellents are inhibitors of mosquito odorant receptors for oviposition attractants

In addition to its primary function as an insect repellent, DEET has many “off-label” properties, including a deterrent effect on the attraction of gravid female mosquitoes. DEET negatively affects oviposition sites. While deorphanizing odorant receptors (ORs) using the Xenopus oocyte recording system, we have previously observed that DEET generated outward (inhibitory) currents on ORs sensitive to oviposition attractants. Here, we systematically investigated these inhibitory currents. We recorded dose-dependent outward currents elicited by DEET and other repellents on ORs from Culex quinquefasciatus, Aedes aegypti, and Anopheles gambiae. Similar responses were observed with other plant-derived and plant-inspired compounds, including methyl jasmonate and methyl dihydrojasmolate. Inward (regular) currents elicited by skatole upon activation of CquiOR21 were modulated when this oviposition attractant was coapplied with a repellent. Compounds that generate outward currents in ORs sensitive to oviposition attractants elicited inward currents in a DEET-sensitive receptor, CquiOR136. The best ligand for this receptor, methyl dihydrojasmolate, showed repellency activity but was not as strong as DEET in our test protocol.

Attraction of mosquitoes to primate odours and implications for zoonotic Plasmodium transmission.

Vector‐borne diseases often originate from wildlife and can spill over into the human population. One of the most important determinants of vector‐borne disease transmission is the host preference of mosquitoes. Mosquitoes with a specialised host preference are guided by body odours to find their hosts in addition to carbon dioxide. Little is known about the role of mosquito host preference in the spillover of pathogenic agents from humans towards animals and vice versa. In the Republic of Congo, the attraction of mosquitoes to primate host odours was determined, as well as their possible role as malaria vectors, using odour‐baited traps mimicking the potential hosts of mosquitoes. Most of the mosquito species caught showed a generalistic host preference. Anopheles obscurus was the most abundant Anopheles mosquito, with a generalistic host preference observed from the olfactory response and the detection of various Plasmodium parasites. Interestingly, Culex decens showed a much higher attraction towards chimpanzee odours than to human or cow odours. Human Plasmodium parasites were observed in both human and chimpanzee blood, although not in the Anopheles mosquitoes that were collected. Understanding the role of mosquito host preference for cross‐species parasite transmission provides information that will help to determine the risk of spillover of vector‐borne diseases.

House sparrow uropygial gland secretions do not attract ornithophilic nor mammophilic mosquitoes.

Mosquito feeding preferences determine host-vector contact rates and represent a key factor in the transmission of vector-borne pathogens. The semiochemical compounds of which vertebrate odours are composed probably play a role in mosquito host choice. Birds spread secretions from uropygial gland over their feathers to protect their plumage, comprising behaviour that may in turn affect odour profiles. Although uropygial secretions are expected to modify the attractiveness of birds to mosquitoes, contradictory findings have been reported. Mosquito species differ in their feeding preferences, with some species feeding mainly on birds (ornithophilic species) and others on mammals (mammophilic species). Consequently, it is possible that ornithophilic and mammophilic species differ in their response to uropygial gland secretions. Using a dual-choice olfactometer, the present study tests this hypothesis by comparing the behavioural response to uropygial gland secretions from juvenile male and female house sparrows (Passer domesticus) in the ornithophilic Culex pipiens and the mammophilic Aedes (Ochlerotatus) caspius mosquitoes. No differences were found in the response of either mosquito species to the uropygial gland secretions. Therefore, the preference of ornithophilic mosquitoes for avian hosts is apparently not explained by a greater attraction of mosquitoes to the uropygial gland secretion odour when presented in combination with a CO2 -enriched airflow.

Comparison of the larvicidal and adult mosquito attractant efficacy between straw mushroom Volvariella volvacea extract and octenol (1-octen-3-ol) on mosquito vectors (Diptera: Culicidae)

Larvicidal Activity of Tephrosia purpurea, (L) Against the Larvae of Culex quinquefasiciatusDeepak Kumar, P. Dhamodaran, Nilani P, N. Balakrishnan

Ultraviolet inflorescence cues enhance attractiveness of inflorescence odour to Culex pipiens mosquitoes.

Inflorescence patterns of ultraviolet (UV) absorption and UV-reflection are attractive to many insect pollinators. To understand whether UV inflorescence cues affect the attraction of nectar-foraging mosquitoes, we worked with the common house mosquito, Culex pipiens and with two plant species exhibiting floral UV cues: the tansy, Tanacetum vulgare, and the common hawkweed Hieraciumm lachenalii. Electroretinograms revealed that Cx. pipiens eyes can sense UV wavelengths, with peak sensitivity at 335 nm. Behavioural bioassays divulged that UV inflorescence cues enhance the attractiveness of inflorescence odour. In the presence of natural floral odour, female Cx. pipiens were attracted to floral patterns of UV-absorption and UV-reflection but preferred uniformly UV-dark inflorescences. Moreover, Cx. pipiens females preferred UV-dark and black inflorescence models to UV-dark and yellow inflorescence models. With feathers and pelts of many avian and mammalian hosts also being UV-dark and dark-coloured, foraging Cx. pipiens females may respond to analogous visual cues when they seek nectar and vertebrate blood resources.

Secondary Freeform Lens Device Design with Stearic Acid for A Low-Glare Mosquito-Trapping System with Ultraviolet Light-Emitting Diodes

Dengue fever is a public health issue of global concern. Taiwan is located in the subtropical region featuring humid and warm weather, which is conducive to the breeding of mosquitoes and flies. Together with global warming and the increasing frequency of international exchanges, in addition to the outbreak of pandemics and dengue fever, the number of people infected has increased rapidly. This study is dedicated to the development of a new mosquito-trapping system. Research has shown that specific wavelengths, colors, and temperatures are highly attractive to both Aedes aegypti and Aedes albopictus. In this study, we create equipment which effectively improves the trapping capabilities of mosquitoes in a wider field. The design of the special Secondary Freeform Lens Device (SFLD) is used to expand the range for trapping mosquitoes and create illumination uniformity; it also directs light downward for the protection of users’ eyes. In addition, we use the correct amount of stearic acid as a mosquito attractant to allow a better control effect against mosquitoes during the day. In summary, when the UV LED mosquito trapping system is combined with a quadratic free-form lens, the experimental results show that the system can extend the capture range to 100 π m2 in which the number of captured mosquitoes is increased by about 350%.

PLANT INFUSIONS MEDIATE OVIPOSITION OF MALARIA, DENGUE AND FILARIASIS VECTORS: PUSH-PULL APPROACH FOR VECTOR SURVEILLANCE AND CONTROL

ABSTRACT Semiochemicals are small organic compounds that mediate interactions between organisms by transmitting chemical messages. They are used by insects for intra- and inter-species communication in their ecosystem. Mosquitoes transmit malaria, dengue, West Nile virus, chikungunya, yellow fever, filariasis and encephalitis to human beings across the globe. Mosquitoes perceive semiochemicals in their environment respectively emanating from potential hosts and habitats by the sensory apparatus and act wisely for the benefit of their progeny. Host seeking and/ avoidance, oviposition site seeking behaviors are governed predominantly by chemical stimuli along with visual cues that ensure blood feeding and subsequent egg laying to complete the gonotrophic cycle. Further, plant materials such as neem, tobacco and their infusions are naturally repulsive to mosquitoes while infusions of Bermuda grass could be a promising avenue for exploring natural attractant molecules using gas-chromatography coupled massspectrometry to identify biologically active molecules. In the laboratory studies one week old infusions of neem seed kernel and dried tobacco leaves reduced 90-97% egg deposition by gravid females of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus mosquitoes, while oviposition substrates treated with one week old infusion of Bermuda grass, Cynodan dactylon received 40-60% increased egg laying compared to control. Through GC-MS analysis of these plant materials revealed several fatty acids, hydrocarbons, nicotine, thymol, ethyl dithioisoindole, -lactone, -elemene, squalene, eudesmenol and stigmasterol that could be responsible for the attraction and repulsion of mosquitoes to respective extracts. Being biological in origin, these semiochemicals are safe to humans and environment, when judiciously used would manage effectively the mosquito menace and mosquito borne diseases.

Sex-biased parasitism in vector-borne disease: Vector preference?

Sex-biased infections are a recurrent observation in vertebrates. In many species, males are more parasitized than females. Two potentially complementary mechanisms are often suggested to explain this pattern: sexual differences in susceptibility mainly caused by the effect of sex hormones on immunity and differential exposure to parasites. Exposure is mostly a consequence of host behavioural traits, but vector-borne parasitic infections involve another degree of complexity due to the active role of vectors in transmission. Blood-sucking insects may make choices based on cues produced by hosts. Regarding malaria, several studies highlighted a male-biased infection by Plasmodium sp in great tits (Parus major). We hypothesize that the mosquito vector, Culex pipiens, might at least partially cause this bias by being more attracted to male birds. Intrinsic variation associated to bird sex would explain a preference of mosquitoes for males. To test this hypothesis, we provide uninfected mosquitoes with a choice between uninfected male and female nestlings. Mosquito choice is assessed by sex typing of the ingested blood. We did not observe any preference for a given sex. This result does not support our prediction of a preference of mosquitoes for male great tits during the nestling period. In conclusion, mosquitoes do not seem to have an intrinsic preference for male nestlings. However, sexually divergent traits (e.g. behaviour, odour, metabolic rate) present in adults may play a role in the attraction of mosquitoes and should be investigated.

Aedes aegypti Mosquitoes Detect Acidic Volatiles Found in Human Odor Using the IR8a Pathway

Mosquitoes use olfaction as a primary means of detecting their hosts. Previously, the functional ablation of a family of Aedes aegypti olfactory receptors, the odorant receptors (ORs), was not sufficient to reduce host seeking in the presence of carbon dioxide (CO2). This suggests the olfactory receptors that remain, such as the ionotropic receptors (IRs), could play a significant role in host detection. To test this, we disrupted the Ir8a co-receptor in Ae. aegypti using CRISPR/Cas9. We found that Ir8a mutant female mosquitoes are not attracted to lactic acid, a behaviorally active component of human sweat, and they lack odor-evoked responses to acidic volatiles. The loss of Ir8a reduces mosquito attraction to humans and their odor. We show that the CO2-detection pathway is necessary but not sufficient for IR8a to detect human odor. Our study reveals that the IR8a pathway is crucial for an anthropophilic vector mosquito to effectively seek hosts. VIDEO ABSTRACT.

Attraction of Female Aedes aegypti (L.) to Aphid Honeydew.

Plant sugar is an essential dietary constituent for mosquitoes, and hemipteran honeydew is one of the many forms of plant sugar that is important to mosquitoes. Many insects rely on volatile honeydew semiochemicals to locate aphids or honeydew itself. Mosquitoes exploit volatile semiochemicals to locate sources of plant sugar but their attraction to honeydew has not previously been investigated. Here, we report the attraction of female yellow fever mosquitoes, Aedes aegypti, to honeydew odorants from the green peach aphid, Myzus persicae, and the pea aphid, Acyrthosiphon pisum, feeding on fava bean, Vicia faba. We used solid phase micro-extraction and gas chromatography-mass spectrometry to collect and analyze headspace odorants from the honeydew of A. pisum feeding on V. faba. An eight-component synthetic blend of these odorants and synthetic odorant blends of crude and sterile honeydew that we prepared according to literature data all attracted female A. aegypti. The synthetic blend containing microbial odor constituents proved more effective than the blend without these constituents. Our study provides the first evidence for anemotactic attraction of mosquitoes to honeydew and demonstrates a role for microbe-derived odorants in the attraction of mosquitoes to essential plant sugar resources.

Small-Molecule Agonists of Ae. aegypti Neuropeptide Y Receptor Block Mosquito Biting

Female Aedes aegypti mosquitoes bite humans to obtain blood to develop their eggs. Remarkably, their strong attraction to humans is suppressed for days after the blood meal by an unknown mechanism. We investigated a role for neuropeptide Y (NPY)-related signaling in long-term behavioral suppression and discovered that drugs targeting human NPY receptors modulate mosquito host-seeking. In a screen of all 49 predicted Ae. aegypti peptide receptors, we identified NPY-like receptor 7 (NPYLR7) as the sole target of these drugs. To obtain small-molecule agonists selective for NPYLR7, we performed a high-throughput cell-based assay of 265,211 compounds and isolated six highly selective NPYLR7 agonists that inhibit mosquito attraction to humans. NPYLR7 CRISPR-Cas9 null mutants are defective in behavioral suppression and resistant to these drugs. Finally, we show that these drugs can inhibit biting and blood-feeding on a live host, suggesting a novel approach to control infectious disease transmission by controlling mosquito behavior. VIDEO ABSTRACT.

Aedes aegypti Ir8a mutant female mosquitoes show increased attraction to standing water

ABSTRACTThe detection of water sources is crucial for insects such as mosquitoes to avoid desiccation and survive. In addition, mosquitoes use humidity cues to successfully navigate the environment to find a suitable oviposition site. Previous studies have implicated some members of the ionotropic receptor family in humidity sensing by Drosophila. Here, we investigate if IR8a co-receptor mediates water detection in Aedes aegypti mosquitoes. Using a simple behavioral assay, we examined the attraction of Ir8a mutant mosquitoes to standing water. Ir8a mutant mosquitoes were able to discriminate between traps containing water and those without as well as wild-type and heterozygous control females. Surprisingly, the female mutants were more robustly drawn to standing water than control mosquitoes. Further investigation revealed that the increased behavioral attraction to water is likely not mediated by a metabolic need or an activity defect.

PENGENDALIAN NYAMUK AEDES SPP MENGGUNAKAN PERANGKAP ALAMIAH

Aedes spp mosquito is the primary vector or the main transmitter of dengue fever. it’s existence cause public health disturbing. Many research are being done to find ways of controlling mosquitoes, one of them by using a mosquito trap attractants. The purpose of this study was to determine the effectiveness of the addition of attractants to modified mosquito trap to the Aedes aegypti mosquitoes control. The study design using analytical methods with a "post-test only control group design". The number of mosquitoes that are used at each observation cage was 30, with 9 times repetition. One way ANOVA used to analized the data then followed by LSD test. Results modifications mosquito trap attractants addition of palm sugar solution mixed with yeast bread is more effective (ρ = 0.000) of the yeast mixed tape.

Behavioral responses of gravid Culex quinquefasciatus, Aedes aegypti, and Anopheles quadrimaculatus mosquitoes to aquatic macrophyte volatiles.

Mosquitoes use many cues to assess whether a habitat is conducive for reproduction, possibly including the presence of stimuli from aquatic macrophytes. The effect of water infusions of water hyacinth (Eichhornia crassipes), water lettuce (Pista stratioles), parrotfeather (Myriophyllum aquaticum), and water pennywort (Hydrocotyle umbellata) on mosquito oviposition and attraction was investigated. Gravid Culex quinquefasciatus deposited significantly more egg rafts in water hyacinth, water lettuce, or Bermuda hay (positive control) infusions compared to water, while water pennywort and parrotfeather infusions did not differ from water. In-flight attraction responses of Cx. quinquefasciatus, Aedes aegypti, and Anopheles quadrimaculatus were evaluated. The strongest attraction of gravid Cx. quinquefasciatus and Ae. aegypti occurred in the presence of volatiles from infusions of water hyacinth and water lettuce, which were equal in attractiveness to hay infusion. Water pennywort and parrotfeather infusions were not attractive. Gravid An. quadrimaculatus were not attracted to aquatic plant volatiles. The results suggest that water hyacinth and water lettuce emit volatile chemicals that attract two of three mosquito species tested and stimulate oviposition by Cx. quinquefasciatus, demonstrating that the level of attraction of aquatic plant volatiles varies among species in ways that may have relevance to bait-based detection and control methods.