scholarly journals Chemical signatures of human odour generate a unique neural code in the brain of Aedes aegypti mosquitoes

2020 ◽  
Author(s):  
Zhilei Zhao ◽  
Jessica L. Zung ◽  
Alexis L. Kriete ◽  
Azwad Iqbal ◽  
Meg A. Younger ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Mosquito Control ◽  
Control Strategies ◽  
Relative Concentration ◽  
Volatile Chemicals ◽  
Host Seeking ◽  
Olfactory Glomeruli ◽  
Efficient Vector ◽  
Human Odour ◽  
Long Chain

AbstractA globally invasive form of the mosquito Aedes aegypti specializes in biting humans, making it an efficient vector of dengue, yellow fever, Zika, and chikungunya viruses. Host-seeking females strongly prefer human odour over the odour of non-human animals, but exactly how they distinguish the two is not known. Vertebrate odours are complex blends of volatile chemicals with many shared components, making discrimination an interesting sensory coding challenge. Here we show that human and animal odour blends evoke activity in unique combinations of olfactory glomeruli within the Aedes aegypti antennal lobe. Human blends consistently activate a ‘universal’ glomerulus, which is equally responsive to diverse animal and nectar-related blends, and a more selective ‘human-sensitive’ glomerulus. This dual signal robustly distinguishes humans from animals across concentrations, individual humans, and diverse animal species. Remarkably, the human-sensitive glomerulus is narrowly tuned to the long-chain aldehydes decanal and undecanal, which we show are consistently enriched in (though not specific to) human odour and which likely originate from unique human skin lipids. We propose a model of host-odour coding wherein normalization of activity in the human-sensitive glomerulus by that in the broadly-tuned universal glomerulus generates a robust discriminatory signal of the relative concentration of long-chain aldehydes in a host odour blend. Our work demonstrates how animal brains may distil complex odour stimuli of innate biological relevance into simple neural codes and reveals novel targets for the design of next-generation mosquito-control strategies.

Urban Landscape Features Influence the Movement and Distribution of the Australian Container-Inhabiting Mosquito Vectors Aedes aegypti (Diptera: Culicidae) and Aedes notoscriptus (Diptera: Culicidae)

2019 ◽  
Author(s):  
Brendan J Trewin ◽  
Daniel E Pagendam ◽  
Myron P Zalucki ◽  
Jonathan M Darbro ◽  
Gregor J Devine ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Urban Landscape ◽  
Mosquito Control ◽  
Control Strategies ◽  
Oviposition Behavior ◽  
Gaussian Kernel ◽  
Mosquito Vectors ◽  
Landscape Features ◽  
Rainwater Tanks

Abstract Urban landscape features play an important role in the distribution and population spread of mosquito vectors. Furthermore, current insecticide and novel rear-and-release strategies for urban mosquito management rarely consider the spatial structure of the landscape when applying control practices. Here, we undertake a mark-recapture experiment to examine how urban features influence the movement and distribution of Australian container-inhabiting Aedes vectors. We pay attention to the role of semipermanent water storage containers, called rainwater tanks, and the influence of movement barriers, such as roads, on the spread and distribution of vector populations. Results suggest that Aedes aegypti (Linnaeus) (Diptera: Culicidae) were more likely to be captured around rainwater tanks, and that released males travel throughout residential blocks but do not cross roads. Conversely, female Aedes notoscriptus (Skuse) (Diptera: Culicidae) movement was uninhibited by roads and rainwater tanks did not influence female distribution or oviposition behavior. Using an isotropic Gaussian kernel framework, we show that vector movement is likely to be greater when applying a temporal effect, than when estimated by traditional methods. We conclude that a greater understanding on the role of urban features on vector movement will be important in the new age of rear-and-release mosquito control strategies, particularly those where estimations of movement are important for ensuring efficacy of application.

scholarly journals The juvenile hormone receptor Methoprene-tolerant is involved in the sterilizing effect of pyriproxyfen on adult Aedes aegypti mosquitoes

2020 ◽  
Author(s):  
Tahmina Hossain Ahmed ◽  
T. Randolph Saunders ◽  
Donald Mullins ◽  
Mohammad Zillur Rahman ◽  
Jinsong Zhu
Keyword(s):  
Aedes Aegypti ◽  
Juvenile Hormone ◽  
Mosquito Control ◽  
Fat Body ◽  
Control Strategies ◽  
Follicular Development ◽  
Blood Feeding ◽  
Oocyte Development ◽  
Hormonal Responses ◽  
Before And After

AbstractExposure of adult mosquitoes to pyriproxyfen (PPF), an analog of insect juvenile hormone (JH), has shown promise to effectively sterilize female mosquitoes. However, the underlying mechanisms of the PPF-induced decrease in mosquito fecundity are largely unknown. We performed a comprehensive study to dissect the mode of PPF action in Aedes aegypti mosquitoes. Exposure to PPF prompted the overgrowth of primary follicles in sugar-fed Ae. aegypti females but blocked the development of primary follicles at Christopher’s Stage III after blood feeding. Secondary follicles were precociously activated in PPF-treated mosquitoes. Moreover, PPF substantially altered the expression of many genes that are essential for mosquito physiology and oocyte development in the fat body and ovary. In particular, many metabolic genes were differentially expressed in response to PPF treatment, thereby affecting the mobilization and utilization of energy reserves. Furthermore, PPF treatment on the previtellogenic female adults considerably modified mosquito responses to JH and 20-hydroxyecdysone (20E), two major hormones that govern mosquito reproduction. Krüppel homolog 1, a JH-inducible transcriptional regulator, showed consistently elevated expression after PPF exposure. Conversely, PPF upregulated the expression of several key players of the 20E regulatory cascades, including HR3 and E75A, in the previtellogenic stage. After blood-feeding, the expression of these 20E response genes was significantly weaker in PPF-treated mosquitoes than the solvent-treated control groups. RNAi-mediated knockdown of the Methoprene-tolerant (Met) protein, the JH receptor, partially rescued the impaired follicular development after PPF exposure and substantially increased the hatching of the eggs produced by PPF-treated female mosquitoes. Thus, the results suggested that PPF relied on Met to exert its sterilizing effects on female mosquitoes. In summary, this study finds that PPF exposure disturbs normal hormonal responses and metabolism in Ae. aegypti, shedding light on the molecular targets and the downstream signaling pathways activated by PPF.Author summaryAedes aegypti mosquitoes are responsible for the transmission of dengue, yellow fever, chikungunya, and Zika fever. Insecticides are widely used as the primary tool in the prevention and control of these infectious diseases. In light of the rapid increase of insecticide resistance in mosquito populations, there is an urgent need to find new classes of insecticides with a different mode of action. Here we found that pyriproxyfen, an analog of insect juvenile hormone (JH), had a large impact on the oocyte development, both before and after blood feeding, in female mosquitoes. Pyriproxyfen disturbed normal hormonal responses and caused metabolic shifting in female adults. These actions appear to collectively impair oocyte development and substantially reduce viable progenies of female mosquitoes. Besides, we demonstrated the involvement of the JH receptor Met in pyriproxyfen-induced female sterilization. This study significantly advances our understanding of mosquito reproductive biology and the molecular basis of pyriproxyfen action, which are invaluable for the development of new mosquito control strategies.

scholarly journals Current Status of Aedes aegypti Insecticide Resistance Development from Banjarmasin, Kalimantan, Indonesia

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
P. H. Hamid ◽  
V. I. Ninditya ◽  
J. Prastowo ◽  
A. Haryanto ◽  
A. Taubert ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Point Mutation ◽  
Mosquito Control ◽  
Control Strategies ◽  
Current Status ◽  
Resistance Development ◽  
Health Authorities ◽  
Public Health Authorities ◽  
High Level

Aedes aegypti represents the principal vector of many arthropod-borne diseases in tropical areas worldwide. Since mosquito control strategies are mainly based on use of insecticides, resistance development can be expected to occur in frequently exposed Ae. aegypti populations. Surveillance on resistance development as well as testing of insecticide susceptibility is therefore mandatory and needs further attention by national/international public health authorities. In accordance, we here conducted a study on Ae. aegypti resistance development towards several often used insecticides, i.e., malathion, deltamethrin, permethrin, λ-cyhalothrin, bendiocarb, and cyfluthrin, in the periurban area of Banjarmasin city, Kalimantan, Indonesia. Our results clearly showed resistance development of Ae. aegypti populations against tested insecticides. Mortalities of Ae. aegypti were less than 90% with the highest resistance observed against 0.75% permethrin. Collected mosquitoes from Banjarmasin also presented high level of resistance development to 0.1% bendiocarb. Molecular analysis of voltage-gated sodium channel (Vgsc) gene showed significant association of V1016G gene point mutation in resistance Ae. aegypti phenotypes against 0.75% permethrin. However, F1534C gene point mutation did not correlate to Ae. aegypti insecticide resistance to 0.75% permethrin. Irrespective of periurban areas in Kalimantan considered as less densed island of Indonesia, Ae. aegypti-derived resistance to different routinely applied insecticides occurred. Our findings evidence that Ae. aegypti insecticide resistance is most likely spreading into less populated areas and thus needs further surveillance in order to delay Ae. aegypti resistance development.

scholarly journals Workshop for priority-setting in Aedes aegypti control interventions in Latin America and the Caribbean: a policy dialogue

2019 ◽  
Vol 35 (4) ◽  
Author(s):  
Agustin Ciapponi ◽  
Ariel Bardach ◽  
Andrea Alcaraz ◽  
María Belizán ◽  
Daniel Jones ◽  
...  
Keyword(s):  
Latin America ◽  
Aedes Aegypti ◽  
Vector Control ◽  
Priority Setting ◽  
Mosquito Control ◽  
Control Strategies ◽  
Policy Dialogue ◽  
Regional Research ◽  
Deliberative Process ◽  
The Caribbean

This article presents the results of a dialogue between decision-makers and experts in Latin America and the Caribbean on priority-setting for interventions and studies on Aedes aegypti control. The article is part of a project that included a systematic review of mosquito control strategies and a qualitative study with key informants from the region. Using a collective deliberative process assisted by the results of the above-mentioned projects, a list of priorities was developed by consensus for the implementation of vector control strategies and the development of key regional research lines. It was agreed that the best strategy is integrated vector management, divided into: (a) chemical control; (b) biological control; (c) environmental management; (d) community participation; and (e) integrated surveillance. The workshop highlighted the crucial role of government leadership and inter-sector coordination between government agencies and civil society stakeholders. The proposed priorities for research lines were: Ae. aegypti vector competence and associated factors; community components of interventions; incorporation of technology into vector control and monitoring; most efficient modalities of integrated surveillance; entomological indicators with the best predictive capacity; and resistance to insecticides. The policy dialogue methodology allowed validating and enriching the results of other levels of research, besides establishing priorities for regional research and control strategies.

scholarly journals Antiviral Effectors and Gene Drive Strategies for Mosquito Population Suppression or Replacement to Mitigate Arbovirus Transmission by Aedes aegypti

Insects ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 52 ◽  
Author(s):  
Adeline Williams ◽  
Alexander Franz ◽  
William Reid ◽  
Ken Olson
Keyword(s):  
Aedes Aegypti ◽  
Disease Transmission ◽  
Mosquito Control ◽  
Control Strategies ◽  
Mosquito Vector ◽  
Close Monitoring ◽  
Gene Drive ◽  
Population Replacement ◽  
Effector Genes ◽  
Population Suppression

The mosquito vector Aedes aegypti transmits arthropod-borne viruses (arboviruses) of medical importance, including Zika, dengue, and yellow fever viruses. Controlling mosquito populations remains the method of choice to prevent disease transmission. Novel mosquito control strategies based on genetically manipulating mosquitoes are being developed as additional tools to combat arbovirus transmission. Genetic control of mosquitoes includes two basic strategies: population suppression and population replacement. The former aims to eliminate mosquito populations while the latter aims to replace wild populations with engineered, pathogen-resistant mosquitoes. In this review, we outline suppression strategies being applied in the field, as well as current antiviral effector genes that have been characterized and expressed in transgenic Ae. aegypti for population replacement. We discuss cutting-edge gene drive technologies that can be used to enhance the inheritance of effector genes, while highlighting the challenges and opportunities associated with gene drives. Finally, we present currently available models that can estimate mosquito release numbers and time to transgene fixation for several gene drive systems. Based on the recent advances in genetic engineering, we anticipate that antiviral transgenic Ae. aegypti exhibiting gene drive will soon emerge; however, close monitoring in simulated field conditions will be required to demonstrate the efficacy and utility of such transgenic mosquitoes.

Pre- and Post-Intervention Study on Aedes Larvae in Water Storage Containers Adding of Native Larvivorous Fish Aplocheilus panchax in Hpa-an Township, Kayin State

2019 ◽  
Vol 31 (2) ◽  
pp. 99-104
Keyword(s):  
Aedes Aegypti ◽  
Mosquito Control ◽  
Control Strategies ◽  
Water Storage ◽  
Hemorrhagic Fever ◽  
Control Agent ◽  
Test Area ◽  
Post Intervention ◽  
Storage Containers ◽  
Study Laboratory

Effective mosquito control strategies in temporary water storage containers in community are urgently needed to reduce dengue fever and dengue hemorrhagic fever through mosquito larvae reduction without harmful to environment, ecosystems and community. For biological control of Aedes aegypti larvae, native larvivorus fish as Aplocheilus panchax were collected from Hpa-an Township, Kayin State. Mingalar Ywar Thit and Taung Nar Village were selected as test and control villages and 51 households each were randomly selected to recruit the study. Laboratory and field study were done from February 2016 to January 2017. In the laboratory, a series of laboratory experiments compared Aedes larva consuming rates of Aplocheilus panchax and Trichogaster trichopterus in different water volumes, in order to determine their potential as larva control agent in water storage containers. In the field, Aedes larvae and pupae positivity in containers were recorded in both villages. During intervention, two Aplocheilus panchax were put into all major, minor and miscellaneous containers monthly for 3 months in test area of Mingalar Ywar Thit Village. Larval and pupal indices were determined before and after intervention. Laboratory result found that one gram weight of Aplocheilus panchax consumed 463.04 3rd and 4th instar Aedes larvae within 24 hours. It was 3.727 fold higher in consuming rate than one gram of Trichogaster trichopterus against 124.24 Aedes aegypti larvae. After intervention, House Index (HI), Container Index (CI) and Breteau Index (BI) were significantly reduced from 86.27%, 59.86% and 172.55 to 1.96%, 1.36% and 3.92, respectively (P<0.05). Hundred percent reduction was found in key containers and 90% reduction was found in key premises in test area. Pupal indices were also significantly reduced. Native larvivorus fish Aplocheilux panchax is an efficient biological agent for the control of DF and DHF vector Aedes immature stages in Kayin State. The biological method is simple and cost-effective method for control of DF/DHF in community.

scholarly journals Physiological and Environmental Factors Affecting the Composition of the Ejaculate in Mosquitoes and Other Insects

Insects ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 74 ◽  
Author(s):  
Megan Meuti ◽  
Sarah Short
Keyword(s):  
Reproductive Biology ◽  
Mosquito Control ◽  
Seminal Fluid ◽  
Control Strategies ◽  
Abiotic Factors ◽  
Mosquito Species ◽  
Future Research ◽  
Factors Affecting ◽  
Host Seeking ◽  
The Individual

In addition to transferring sperm, male mosquitoes deliver several proteins, hormones and other factors to females in their seminal fluid that inhibit remating, alter host-seeking behaviors and stimulate oviposition. Recently, bioinformatics, transcriptomics and proteomics have been used to characterize the genes transcribed in male reproductive tissues and the individual proteins that are delivered to females. Thanks to these foundational studies, we now understand the complexity of the ejaculate in several mosquito species. Building on this work, researchers have begun to identify the functions of various proteins and hormones in the male ejaculate, and how they mediate their effects on female mosquitoes. Here, we present an overview of these studies, followed by a discussion of an under-studied aspect of male reproductive physiology: the effects of biotic and abiotic factors on the composition of the ejaculate. We argue that future research in this area would improve our understanding of male reproductive biology from a physiological and ecological perspective, and that researchers may be able to leverage this information to study key components of the ejaculate. Furthermore, this work has the potential to improve mosquito control by allowing us to account for relevant factors when implementing vector control strategies involving male reproductive biology.

scholarly journals Genetic Characterization of Chikungunya Virus in Field-Caught Aedes aegypti Mosquitoes Collected during the Recent Outbreaks in 2019, Thailand

Pathogens ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 121 ◽  
Author(s):  
Intayot ◽  
Phumee ◽  
Boonserm ◽  
Sor-suwan ◽  
Buathong ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
South African ◽  
Chikungunya Virus ◽  
Mosquito Control ◽  
Control Strategies ◽  
Pathogen Transmission ◽  
Sequencing Analysis ◽  
Chikv Infection ◽  
Infected Female ◽  
Health Authorities

Chikungunya virus (CHIKV) is a mosquito-borne virus belonging to the genus Alphavirus. The virus is transmitted to humans by the bite of infected female Aedes mosquitoes, primarily Aedes aegypti. CHIKV infection is spreading worldwide, and it periodically sparks new outbreaks. There are no specific drugs or effective vaccines against CHIKV. The interruption of pathogen transmission by mosquito control provides the only effective approach to the control of CHIKV infection. Many studies have shown that CHIKV can be transmitted among the Ae. aegypti through vertical transmission. The previous chikungunya fever outbreaks in Thailand during 2008–2009 were caused by CHIKV, the East/Central/South African (ECSA) genotype. Recently, there have been 3794 chikungunya cases in 27 provinces reported by the Bureau of Epidemiology of Health Ministry, Thailand during 1 January–16 June 2019; however, the cause of the re-emergence of CHIKV outbreaks is uncertain. Therefore, the aims of this study were to detect and analyze the genetic diversity of CHIKV infection in field-caught mosquitoes. Both female and male Ae. aegypti were collected from endemic areas of Thailand, and CHIKV detection was done by using E1-nested RT-PCR and sequencing analysis. A total of 1646 Ae. aegypti samples (900 females and 746 males) were tested. CHIKV was detected in 54 (3.28%) and 14 samples (0.85%) in female and male mosquitoes, respectively. Seventeen samples of female Ae. aegypti collected from the Ubon Ratchathani, Chiang Rai, Chiang Mai, Nakhon Sawan, and Songkhla provinces found mutation at E1: A226V. Interestingly, E1: K211E mutation was observed in 50 samples collected from Nong Khai, Bangkok, Prachuap Khiri Khan, and Krabi. In addition, the phylogenetic tree indicated that CHIKV in Ae. aegypti samples were from the Indian Ocean Clade and East/South African Clade. Both clades belong to the ECSA genotype. The information obtained from this study could be used for prediction, epidemiological study, prevention, and effective vector control of CHIKV. For instance, a novel CHIKV strain found in new areas has the potential to lead to a new outbreak. Health authorities could plan and apply control strategies more effectively given the tools provided by this research.

scholarly journals The Effect of Permethrin Resistance on Aedes aegypti Transcriptome Following Ingestion of Zika Virus Infected Blood

Viruses ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 470 ◽  
Author(s):  
Liming Zhao ◽  
Barry Alto ◽  
Dongyoung Shin ◽  
Fahong Yu
Keyword(s):  
Virus Infection ◽  
Aedes Aegypti ◽  
Zika Virus ◽  
Mosquito Control ◽  
Control Strategies ◽  
Detoxification Enzymes ◽  
Pcr Analysis ◽  
Zika Virus Infection ◽  
Induced Changes ◽  
Different Levels

Aedes aegypti (L.) is the primary vector of many emerging arboviruses. Insecticide resistance among mosquito populations is a consequence of the application of insecticides for mosquito control. We used RNA-sequencing to compare transcriptomes between permethrin resistant and susceptible strains of Florida Ae. aegypti in response to Zika virus infection. A total of 2459 transcripts were expressed at significantly different levels between resistant and susceptible Ae. aegypti. Gene ontology analysis placed these genes into seven categories of biological processes. The 863 transcripts were expressed at significantly different levels between the two mosquito strains (up/down regulated) more than 2-fold. Quantitative real-time PCR analysis was used to validate the Zika-infection response. Our results suggested a highly overexpressed P450, with AAEL014617 and AAEL006798 as potential candidates for the molecular mechanism of permethrin resistance in Ae. aegypti. Our findings indicated that most detoxification enzymes and immune system enzymes altered their gene expression between the two strains of Ae. aegypti in response to Zika virus infection. Understanding the interactions of arboviruses with resistant mosquito vectors at the molecular level allows for the possible development of new approaches in mitigating arbovirus transmission. This information sheds light on Zika-induced changes in insecticide resistant Ae. aegypti with implications for mosquito control strategies.

Distribution of Aedes aegypti and Aedes albopictus in different eco zones of Thiruvananthapuram city with special reference to dengue viremia in humans

ENTOMON ◽  
2018 ◽  
Vol 43 (4) ◽  
pp. 223-230
Author(s):  
S. Sunil Kumar ◽  
D.A. Evans ◽  
K. Muthulakshmi ◽  
T. DilipKumar ◽  
R. Heera Pillai ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Aedes Albopictus ◽  
Dengue Shock Syndrome ◽  
Single Step ◽  
Equal Distribution ◽  
Distribution Study ◽  
Urban Zone ◽  
High Prevalence ◽  
Vector Management ◽  
Efficient Vector

Mosquito index study of three ecologically different ecozones of the Thiruvananthapuram district, Kerala showed sharp difference on the proportionate distribution of Aedes aegypti and Aedes albopictus. Human dengue viremia (HDV) was very high in those ecozones where A.aegypti density was high and HDV was low where A.albopictus was high. In a coastal zone of Thiruvananthapuram city, A. aegypti was the most abundant vector and in a hilly, arid suburban zone, A.albopictus was the abundant vector. In the urban zone both species of mosquitoes showed equal distribution. Study on the circulating serotypes in the serum of HDV by Single step single tube Multiplex PCR showed all the four serotypes viz DENV1, DENV2, DENV3 and DENV4 in patients of Thiruvananthapuram city, which indicated the possibility of Dengue Shock Syndrome, unless there is efficient vector management. Among the four dengue serotypes, Type 1 was the most abundant virus. Abundance of microhabitats in Thiruvananthapuram city, which support A. aegypti may be the reason for high prevalence of dengue fever in the urban zone.

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