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Vajda ÉA, Ross A, Doum D, Fairbanks EL, Chitnis N, Hii J, Moore SJ, Richardson JH, Macdonald M, Sovannaroth S, Kimheng P, McIver DJ, Tatarsky A, Lobo NF. Field evaluation of a volatile pyrethroid spatial repellent and etofenprox treated clothing for outdoor protection against forest malaria vectors in Cambodia. Sci Rep 2024; 14:17348. [PMID: 39069597 PMCID: PMC11284218 DOI: 10.1038/s41598-024-67470-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 07/11/2024] [Indexed: 07/30/2024] Open
Abstract
Cambodia's goal to eliminate malaria by 2025 is challenged by persistent transmission in forest and forest fringe areas, where people are exposed to Anopheles mosquito bites during the day and night. Volatile pyrethroid spatial repellents (VPSRs) and insecticide-treated clothing (ITC) could address these gaps. This study evaluated the outdoor application of one passive transfluthrin-based VPSR, four etofenprox-ITCs paired with a picaridin topical repellent, and a combination of VPSR and ITC against wild Anopheles landing in Cambodia. A 7 × 7 Latin-square study was conducted over 49 collection nights in temporary open structures in Mondulkiri Province. All interventions substantially reduced Anopheles landing, with protective efficacy ranging from 61 to 95%. Mathematical modeling showed significant reductions in vectoral capacity, especially with the combined ITC and VPSR and VPSR alone, albeit with decreased effectiveness over time. These interventions have the potential to reduce outdoor and daytime Anopheles biting, offering valuable contributions to malaria elimination efforts in Cambodia and the Greater Mekong Subregion, contingent upon achieving effective coverage and adherence.
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Affiliation(s)
- Élodie A Vajda
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA.
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland.
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland.
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Dyna Doum
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
- Health Forefront Organization, Phnom Penh, Cambodia
| | - Emma L Fairbanks
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Jeffrey Hii
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Sarah J Moore
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 74, Bagamoyo, Tanzania
| | - Jason H Richardson
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, L3 5QA, UK
| | - Michael Macdonald
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, L3 5QA, UK
| | - Siv Sovannaroth
- National Center for Parasitology, Entomology and Malaria Control, 477, Phnom Penh, Cambodia
| | - Pen Kimheng
- Department of Health of Mondulkiri, C5XX+CP4, 76, Krong Saen Monourom, Cambodia
| | - David J McIver
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Allison Tatarsky
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Neil F Lobo
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
- University of Notre Dame, Notre Dame, IN, 46556, USA
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Batume C, Mulongo IM, Ludlow R, Ssebaale J, Randerson P, Pickett JA, Mukisa IM, Scofield S. Evaluating repellence properties of catnip essential oil against the mosquito species Aedes aegypti using a Y-tube olfactometer. Sci Rep 2024; 14:2269. [PMID: 38280895 PMCID: PMC10821859 DOI: 10.1038/s41598-024-52715-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/23/2024] [Indexed: 01/29/2024] Open
Abstract
The mosquito species Aedes aegypti (L.) is known to act as a vector in the transmission of various diseases, including dengue fever and yellow fever. The use of insect repellents is one of precautionary measures used to mitigate the risk of these diseases in humans by reducing mosquito biting. Nepetalactone, a potent natural insect repellent primarily found in catnip (Nepeta cataria) essential oil, has emerged as a promising candidate for mosquito repellence. Here, we evaluated the potential of catnip essential oil (> 95% nepetalactone) for use as a mosquito repellent. Using a Y-tube olfactometer and human hands as an attractant, we analysed the effectiveness of catnip oil at repelling the mosquito species Aedes aegypti. We tested a range of dilutions of catnip essential oil and found that concentrations as low as 2% were effective at repelling > 70% of mosquitoes for between one and four hours after repellent application. These findings suggest that nepetalactone could potentially be used as a natural, effective alternative to synthetic mosquito repellents, thereby offering protection against vector-borne diseases.
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Affiliation(s)
- Charles Batume
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
| | | | | | | | | | | | - Ivan M Mukisa
- Department of Food Technology and Nutrition, Makerere University, Kampala, Uganda
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Vajda ÉA, Saeung M, Ross A, McIver DJ, Tatarsky A, Moore SJ, Lobo NF, Chareonviriyaphap T. A semi-field evaluation in Thailand of the use of human landing catches (HLC) versus human-baited double net trap (HDN) for assessing the impact of a volatile pyrethroid spatial repellent and pyrethroid-treated clothing on Anopheles minimus landing. Malar J 2023; 22:202. [PMID: 37400831 PMCID: PMC10318828 DOI: 10.1186/s12936-023-04619-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/10/2023] [Indexed: 07/05/2023] Open
Abstract
BACKGROUND The mosquito landing rate measured by human landing catches (HLC) is the conventional endpoint used to evaluate the impact of vector control interventions on human-vector exposure. Non-exposure based alternatives to the HLC are desirable to minimize the risk of accidental mosquito bites. One such alternative is the human-baited double net trap (HDN), but the estimated personal protection of interventions using the HDN has not been compared to the efficacy estimated using HLC. This semi-field study in Sai Yok District, Kanchanaburi Province, Thailand, evaluates the performance of the HLC and the HDN for estimating the effect on Anopheles minimus landing rates of two intervention types characterized by contrasting modes of action, a volatile pyrethroid spatial repellent (VSPR) and insecticide-treated clothing (ITC). METHODS Two experiments to evaluate the protective efficacy of (1) a VPSR and (2) ITC, were performed. A block randomized cross-over design over 32 nights was carried out with both the HLC or HDN. Eight replicates per combination of collection method and intervention or control arm were conducted. For each replicate, 100 An. minimus were released and were collected for 6 h. The odds ratio (OR) of the released An. minimus mosquitoes landing in the intervention compared to the control arm was estimated using logistic regression, including collection method, treatment, and experimental day as fixed effects. RESULTS For the VPSR, the protective efficacy was similar for the two methods: 99.3%, 95% CI (99.5-99.0) when measured by HLC, and 100% (100, Inf) when measured by HDN where no mosquitoes were caught (interaction test p = 0.99). For the ITC, the protective efficacy was 70% (60-77%) measured by HLC but there was no evidence of protection when measured by HDN [4% increase (15-27%)] (interaction test p < 0.001). CONCLUSIONS Interactions between mosquitoes, bite prevention tools and the sampling method may impact the estimated intervention protective efficacy. Consequently, the sampling method must be considered when evaluating these interventions. The HDN is a valid alternative trapping method (relative to the HLC) for evaluating the impact of bite prevention methods that affect mosquito behaviour at a distance (e.g. VPSR), but not for interventions that operate through tarsal contact (e.g., ITC).
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Affiliation(s)
- Élodie A Vajda
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA.
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland.
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland.
| | - Manop Saeung
- Kasetsart University, 50 Thanon Ngamwongwan, Lat Yao, Chatuchak, Bangkok, 10900, Thailand
| | - Amanda Ross
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland
| | - David J McIver
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
| | - Allison Tatarsky
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
| | - Sarah J Moore
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland
- Vector Control Product Testing Unit, Department of Environmental and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Nelson Mandela African Institute of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Tanzania
| | - Neil F Lobo
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
- University of Notre Dame, Notre Dame, IN, 46556, USA
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Bauer IL. The oral repellent - science fiction or common sense? Insects, vector-borne diseases, failing strategies, and a bold proposition. Trop Dis Travel Med Vaccines 2023; 9:7. [PMID: 37381000 DOI: 10.1186/s40794-023-00195-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 06/09/2023] [Indexed: 06/30/2023] Open
Abstract
Over the last decades, unimaginable amounts of money have gone into research and development of vector control measures, repellents, treatment, and vaccines for vector borne diseases. Technological progress and scientific breakthroughs allowed for ever more sophisticated and futuristic strategies. Yet, each year, millions of people still die or suffer from potentially serious consequences of malaria or dengue to more recent infections, such as zika or chikungunya, or of debilitating consequences of neglected tropical diseases. This does not seem value for money. In addition, all current vector control strategies and personal protection methods have shortcomings, some serious, that are either destructive to non-target species or unsatisfactory in their effectiveness. On the other hand, the rapid decline in insect populations and their predators reflects decades-long aggressive and indiscriminate vector control. This major disruption of biodiversity has an impact on human life not anticipated by the well-meaning killing of invertebrates. The objective of this paper is to re-examine current control methods, their effectiveness, their impact on biodiversity, human and animal health, and to call for scientific courage in the pursuit of fresh ideas. This paper brings together topics that are usually presented in isolation, thereby missing important links that offer potential solutions to long-standing problems in global health. First, it serves as a reminder of the importance of insects to human life and discusses the few that play a role in transmitting disease. Next, it examines critically the many currently employed vector control strategies and personal protection methods. Finally, based on new insights into insect chemo-sensation and attractants, this perspective makes a case for revisiting a previously abandoned idea, the oral repellent, and its use via currently successful methods of mass-application. The call is out for focused research to provide a powerful tool for public health, tropical medicine, and travel medicine.
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Affiliation(s)
- Irmgard L Bauer
- College of Healthcare Sciences, Academy - Tropical Health and Medicine, James Cook University, Townsville, QLD, 4811, Australia.
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Singh P, Goyal S, Gupta S, Garg S, Tiwari A, Rajput V, Bates AS, Gupta AK, Gupta N. Combinatorial encoding of odors in the mosquito antennal lobe. Nat Commun 2023; 14:3539. [PMID: 37322224 PMCID: PMC10272161 DOI: 10.1038/s41467-023-39303-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 06/06/2023] [Indexed: 06/17/2023] Open
Abstract
Among the cues that a mosquito uses to find a host for blood-feeding, the smell of the host plays an important role. Previous studies have shown that host odors contain hundreds of chemical odorants, which are detected by different receptors on the peripheral sensory organs of mosquitoes. But how individual odorants are encoded by downstream neurons in the mosquito brain is not known. We developed an in vivo preparation for patch-clamp electrophysiology to record from projection neurons and local neurons in the antennal lobe of Aedes aegypti. Combining intracellular recordings with dye-fills, morphological reconstructions, and immunohistochemistry, we identify different sub-classes of antennal lobe neurons and their putative interactions. Our recordings show that an odorant can activate multiple neurons innervating different glomeruli, and that the stimulus identity and its behavioral preference are represented in the population activity of the projection neurons. Our results provide a detailed description of the second-order olfactory neurons in the central nervous system of mosquitoes and lay a foundation for understanding the neural basis of their olfactory behaviors.
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Affiliation(s)
- Pranjul Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Shefali Goyal
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Smith Gupta
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Sanket Garg
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
- Department of Economic Sciences, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Abhinav Tiwari
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Varad Rajput
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Alexander Shakeel Bates
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Arjit Kant Gupta
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Nitin Gupta
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India.
- Mehta Family Center for Engineering in Medicine, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India.
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Maia PCR, La Corte R, Pires LB, Banfield L, Logan JG, Lima-Camara TN. Increased Repellent Effect of DEET on Aedes aegypti (Diptera: Culicidae) Field Population. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1368-1375. [PMID: 35686335 DOI: 10.1093/jme/tjac068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Indexed: 06/15/2023]
Abstract
Insecticides and repellents are routinely used in Brazil because of the high rates of arbovirus transmission and the nuisance caused by mosquitoes. However, few studies have assessed the effectiveness of repellents against mosquito populations that have been under exposure to xenobiotics, mainly insecticides and repellents. This study investigated the sensitivity of a field population of Aedes aegypti (Linnaeus, 1762) from a dengue-endemic area under high insecticide pressure to N,N-diethylmethylbenzamide (DEET), the active ingredient in common repellent products. The field (Laranjeiras, Sergipe, Brazil) and laboratory (Rockefeller) populations were characterized for the presence of the Val1016Ile kdr mutation, associated with pyrethroid resistance, and locomotor activity. Repellency bioassays were performed to assess the response of the mosquitoes to human odor by exposing them to 10% DEET applied to the skin in ethanol. Samples from the field population showed higher frequency of the kdr mutation, 21.9% homozygous and 21.9% heterozygous, greater locomotor activity and greater sensitivity to DEET than the laboratory population. These results suggest increased sensitivity to DEET in field populations and a possible interaction between insecticide exposure and sensitivity to DEET.
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Affiliation(s)
- Pollyana Conceição Romão Maia
- Programa de Pós-Graduação em Saúde Pública, Faculdade de Saúde Pública, Universidade de São Paulo. Av. Dr. Arnaldo, 715-Cerqueira César, São Paulo-SP, 01246-904, Brazil
| | - Roseli La Corte
- Departamento de Morfologia, Universidade Federal de Sergipe. Av. Mal Rondon s/n São Cristóvão-SE, 49100-000, Brazil
| | - Liandra Brasil Pires
- Departamento de Morfologia, Universidade Federal de Sergipe. Av. Mal Rondon s/n São Cristóvão-SE, 49100-000, Brazil
| | - Lydia Banfield
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel St, London, WC1E 7HT, UK
| | - James G Logan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel St, London, WC1E 7HT, UK
| | - Tamara Nunes Lima-Camara
- Faculdade de Saúde Pública, Universidade de São Paulo. Av. Dr. Arnaldo, 715-Cerqueira César, São Paulo-SP, 01246-904, Brazil
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Pena GA, da Costa Lopes AS, de Morais SHS, do Nascimento LD, dos Santos FRR, da Costa KS, Alves CN, Lameira J. Host-Guest Inclusion Complexes of Natural Products and Nanosystems: Applications in the Development of Repellents. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27082519. [PMID: 35458718 PMCID: PMC9028570 DOI: 10.3390/molecules27082519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 02/08/2023]
Abstract
Repellents are compounds that prevent direct contact between the hosts and the arthropods that are vectors of diseases. Several studies have described the repellent activities of natural compounds obtained from essential oils. In addition, these chemical constituents have been pointed out as alternatives to conventional synthetic repellents due to their interesting residual protection and low toxicity to the environment. However, these compounds have been reported with short shelf life, in part, due to their volatile nature. Nanoencapsulation provides protection, stability, conservation, and controlled release for several compounds. Here, we review the most commonly used polymeric/lipid nanosystems applied in the encapsulation of small organic molecules obtained from essential oils that possess repellent activity, and we also explore the theoretical aspects related to the intermolecular interactions, thermal stability, and controlled release of the nanoencapsulated bioactive compounds.
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Affiliation(s)
- Gueive Astur Pena
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Federal University of Pará, Augusto Correa Street, w/n, Guamá, Belém 66075-110, Brazil; (G.A.P.); (C.N.A.)
| | - Anna Sylmara da Costa Lopes
- Laboratório de Catalálise e Oleoquímica, Federal University of Pará, Augusto Correa Street, w/n, Guamá, Belém 66075-110, Brazil;
| | - Sylvano Heleno Salgado de Morais
- Laboratório de Química Analítica e Ambiental, Federal University of Pará, Augusto Correa Street, w/n, Guamá, Belém 66075-110, Brazil;
| | - Lidiane Diniz do Nascimento
- Museu Paraense Emilio Goeldi, Laboratório Adolpho Ducke, Perimetral Avenue, Nuber 1901, Belém 66077-830, Brazil;
| | | | - Kauê Santana da Costa
- Laboratório de Simulação Computacional, Instituto de Biodiversidade, Universidade Federal do Oeste do Pará, Vera Paz Street, w/n Salé, Santarém 68040-255, Brazil
- Correspondence: (K.S.d.C.); (J.L.)
| | - Cláudio Nahum Alves
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Federal University of Pará, Augusto Correa Street, w/n, Guamá, Belém 66075-110, Brazil; (G.A.P.); (C.N.A.)
| | - Jerônimo Lameira
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Federal University of Pará, Augusto Correa Street, w/n, Guamá, Belém 66075-110, Brazil; (G.A.P.); (C.N.A.)
- Correspondence: (K.S.d.C.); (J.L.)
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Drosophila melanogaster Chemosensory Pathways as Potential Targets to Curb the Insect Menace. INSECTS 2022; 13:insects13020142. [PMID: 35206716 PMCID: PMC8874460 DOI: 10.3390/insects13020142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/19/2022] [Accepted: 01/25/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary The perception and processing of chemosensory stimuli are indispensable to the survival of living organisms. In insects, olfaction and gustation play a critical role in seeking food, finding mates and avoiding signs of danger. This review aims to present updated information about olfactory and gustatory signaling in the fruit fly Drosophila melanogaster. We have described the mechanisms involved in olfactory and gustatory perceptions at the molecular level, the receptors along with the allied molecules involved, and their signaling pathways in the fruit fly. Due to the magnifying problems of disease-causing insect vectors and crop pests, the applications of chemosensory signaling in controlling pests and insect vectors are also discussed. Abstract From a unicellular bacterium to a more complex human, smell and taste form an integral part of the basic sensory system. In fruit flies Drosophila melanogaster, the behavioral responses to odorants and tastants are simple, though quite sensitive, and robust. They explain the organization and elementary functioning of the chemosensory system. Molecular and functional analyses of the receptors and other critical molecules involved in olfaction and gustation are not yet completely understood. Hence, a better understanding of chemosensory cue-dependent fruit flies, playing a major role in deciphering the host-seeking behavior of pathogen transmitting insect vectors (mosquitoes, sandflies, ticks) and crop pests (Drosophila suzukii, Queensland fruit fly), is needed. Using D. melanogaster as a model organism, the knowledge gained may be implemented to design new means of controlling insects as well as in analyzing current batches of insect and pest repellents. In this review, the complete mechanisms of olfactory and gustatory perception, along with their implementation in controlling the global threat of disease-transmitting insect vectors and crop-damaging pests, are explained in fruit flies.
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Montell C. Drosophila sensory receptors-a set of molecular Swiss Army Knives. Genetics 2021; 217:1-34. [PMID: 33683373 DOI: 10.1093/genetics/iyaa011] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 11/17/2020] [Indexed: 01/01/2023] Open
Abstract
Genetic approaches in the fruit fly, Drosophila melanogaster, have led to a major triumph in the field of sensory biology-the discovery of multiple large families of sensory receptors and channels. Some of these families, such as transient receptor potential channels, are conserved from animals ranging from worms to humans, while others, such as "gustatory receptors," "olfactory receptors," and "ionotropic receptors," are restricted to invertebrates. Prior to the identification of sensory receptors in flies, it was widely assumed that these proteins function in just one modality such as vision, smell, taste, hearing, and somatosensation, which includes thermosensation, light, and noxious mechanical touch. By employing a vast combination of genetic, behavioral, electrophysiological, and other approaches in flies, a major concept to emerge is that many sensory receptors are multitaskers. The earliest example of this idea was the discovery that individual transient receptor potential channels function in multiple senses. It is now clear that multitasking is exhibited by other large receptor families including gustatory receptors, ionotropic receptors, epithelial Na+ channels (also referred to as Pickpockets), and even opsins, which were formerly thought to function exclusively as light sensors. Genetic characterizations of these Drosophila receptors and the neurons that express them also reveal the mechanisms through which flies can accurately differentiate between different stimuli even when they activate the same receptor, as well as mechanisms of adaptation, amplification, and sensory integration. The insights gleaned from studies in flies have been highly influential in directing investigations in many other animal models.
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Affiliation(s)
- Craig Montell
- Department of Molecular, Cellular, and Developmental Biology, The Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
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Shrestha B, Lee Y. Mechanisms of DEET gustation in Drosophila. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 131:103550. [PMID: 33549816 DOI: 10.1016/j.ibmb.2021.103550] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/31/2021] [Accepted: 01/31/2021] [Indexed: 06/12/2023]
Abstract
DEET is the most widely used active ingredient in insect repellents and offers protection against insect bites. We previously reported that DEET suppresses the feeding behavior of Drosophila, which is guided by gustatory receptors (GRs) in bitter-sensing gustatory receptor neurons. Here, we sought to identify new candidates using egg-laying assays. Upon screening all GR mutants, GR89a was identified as a potential DEET receptor. Gr89a mutants exhibited reduced oviposition avoidance, feeding avoidance, and electrophysiological responses compared to Gr32a, Gr33a, and Gr66a mutants. However, GR89a was found to modulate DEET avoidance, as demonstrated by genetic and RNA interference assays. Furthermore, we found that DEET ingestion severely affected larval and pupal development and survival, and therefore may act as an effective larvicide.
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Affiliation(s)
- Bhanu Shrestha
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
| | - Youngseok Lee
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea; Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul, 02707, Republic of Korea.
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Hol FJH, Lambrechts L, Prakash M. BiteOscope, an open platform to study mosquito biting behavior. eLife 2020; 9:e56829. [PMID: 32960173 PMCID: PMC7535929 DOI: 10.7554/elife.56829] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 09/05/2020] [Indexed: 01/16/2023] Open
Abstract
Female mosquitoes need a blood meal to reproduce, and in obtaining this essential nutrient they transmit deadly pathogens. Although crucial for the spread of mosquito-borne diseases, blood feeding remains poorly understood due to technological limitations. Indeed, studies often expose human subjects to assess biting behavior. Here, we present the biteOscope, a device that attracts mosquitoes to a host mimic which they bite to obtain an artificial blood meal. The host mimic is transparent, allowing high-resolution imaging of the feeding mosquito. Using machine learning, we extract detailed behavioral statistics describing the locomotion, pose, biting, and feeding dynamics of Aedes aegypti, Aedes albopictus, Anopheles stephensi, and Anopheles coluzzii. In addition to characterizing behavioral patterns, we discover that the common insect repellent DEET repels Anopheles coluzzii upon contact with their legs. The biteOscope provides a new perspective on mosquito blood feeding, enabling the high-throughput quantitative characterization of this lethal behavior.
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Affiliation(s)
- Felix JH Hol
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Insect-Virus Interactions Unit, Institut Pasteur, UMR2000, CNRSParisFrance
- Center for research and Interdisciplinarity, U1284 INSERM, Université de ParisParisFrance
| | - Louis Lambrechts
- Insect-Virus Interactions Unit, Institut Pasteur, UMR2000, CNRSParisFrance
| | - Manu Prakash
- Department of Bioengineering, Stanford UniversityStanfordUnited States
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Shrestha B, Lee Y. Cellular and molecular mechanisms of DEET toxicity and disease-carrying insect vectors: a review. Genes Genomics 2020; 42:1131-1144. [DOI: 10.1007/s13258-020-00991-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 08/20/2020] [Indexed: 12/15/2022]
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13
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Chemosensory and Behavioural Responses of Ixodes scapularis to Natural Products: Role of Chemosensory Organs in Volatile Detection. INSECTS 2020; 11:insects11080502. [PMID: 32759735 PMCID: PMC7469143 DOI: 10.3390/insects11080502] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 01/26/2023]
Abstract
Simple Summary Ticks are responsible of transmitting serious disease agents of importance to human and veterinary health. Despite the importance of repellents, deterrents and acaricides in tick management, little is understood about the types of chemicals recognized and the mechanism behind chemoreception. Being almost totally blind, ticks rely on chemosensation to identify and locate hosts for a successful blood meal and to detect chemical signals in the environment. We explored the neurophysiology of tick chemosensory system in the context of behaviourally-relevant volatile stimuli, including essential oil components, to evaluate how the combination of attractants and plant volatile compounds is detected and processed. The observed inhibition (or deterrent effect) in tick electrophysiological response and behavioural activity, after the tick has been exposed to a binary mixture of attractant and volatile compound, represents an important advancement in understanding how tick olfaction works and what may be the mechanism behind detecting unpleasant odor stimuli and consequently been deterred. These information will provide more insights in developing new natural product-based deterrents for self-protection. Abstract Blacklegged ticks, Ixodes scapularis, represent a significant public health concern due to their vectoring of tick-borne disease. Despite their medical importance, there is still limited knowledge of the chemosensory system of this species, and thus a poor understanding of host-seeking behaviour and chemical ecology. We investigated the electrophysiological sensitivity of adult female blacklegged ticks to attractants and plant-derived compounds via an electrode inserted into the scutum. The response of female ticks to binary mixtures with a constant concentration of a selected attractant (butyric acid) and increasing concentration of volatile organic compounds (VOCs) (geraniol, phenethyl alcohol, β-citronellol, and citral) was recorded. A strict relationship between increasing volatile concentration and a decreasing response was observed for each VOC. Y-tube bioassays confirmed that tick attraction towards butyric acid decreased with the presence of a VOC, which exerted a deterrent effect. To determine the specific role of sensory appendages involved in the detection of attractant chemical stimuli, we tested tick electrophysiological response after removing appendages that house chemosensory sensilla (foretarsi, pedipalps, or both). The chemosensory response was related to the molecular structure of attractant odorant, and the lack of pedipalps significantly reduced olfactory responses, suggesting they play an important role in detecting attractants. This study provides new insight into the neurophysiological mechanisms underlying tick olfaction and the potential for interactions between attractant and deterrent chemical detection.
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Tuorinsky EV, Machtinger ET. Behavioral Inhibition of the House Fly (Diptera: Muscidae) When Exposed to Commercial Equine Fly Repellents. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:518-526. [PMID: 31560398 DOI: 10.1093/jee/toz243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Indexed: 06/10/2023]
Abstract
House flies can have negative consequences on the welfare of horses and other equids. Fly repellents in the form of on-animal sprays, wipes, or spot-ons are the most commonly used fly control method for horses. Many products are available, but repellent efficacy and duration of effectiveness may influence repellent choice by horse owners. A better understanding of the efficacy of common fly repellent products will help guide repellent selection to reduce fly pressure on horses. To evaluate commercially available repellents, house fly behavioral inhibition after application of three products marketed as natural (Ecovet, Equiderma, and Outsmart) and four with synthetic pyrethroids as active ingredients (Bronco, Endure, UltraShield, and Optiforce) was compared at 100, 50, and 25% concentration and at 15, 30, 60, 240, 1,440, and 2,880 min. Time and product were significant at all tested concentrations. The natural products performed as well as or better than the synthetic products at all dilutions and times. Ecovet in particular retained over 75% inhibition of flies for >1 d at the 100 and 50% concentrations. Differences were seen among products with pyrethroids, suggesting that formulation differences significantly affect efficacy. Cost and application suggestions are discussed, and these results will aid horse owners in selecting fly repellents to meet their individual needs.
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Affiliation(s)
| | - Erika T Machtinger
- Department of Entomology, Pennsylvania State University, 4 Chemical Ecology Laboratory, University Park, PA
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15
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Dennis EJ, Dobosiewicz M, Jin X, Duvall LB, Hartman PS, Bargmann CI, Vosshall LB. A natural variant and engineered mutation in a GPCR promote DEET resistance in C. elegans. Nature 2018; 562:119-123. [PMID: 30258230 DOI: 10.1038/s41586-018-0546-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 07/27/2018] [Indexed: 12/16/2022]
Abstract
DEET (N,N-diethyl-meta-toluamide) is a synthetic chemical identified by the US Department of Agriculture in 1946 in a screen for repellents to protect soldiers from mosquito-borne diseases1,2. Since its discovery, DEET has become the world's most widely used arthropod repellent and is effective against invertebrates separated by millions of years of evolution-including biting flies3, honeybees4, ticks5, and land leeches3. In insects, DEET acts on the olfactory system5-12 and requires the olfactory receptor co-receptor Orco7,9-12, but exactly how it works remains controversial13. Here we show that the nematode Caenorhabditis elegans is sensitive to DEET and use this genetically tractable animal to study the mechanism of action of this chemical. We found that DEET is not a volatile repellent, but instead interferes selectively with chemotaxis to a variety of attractant and repellent molecules. In a forward genetic screen for DEET-resistant worms, we identified a gene that encodes a single G protein-coupled receptor, str-217, which is expressed in a single pair of chemosensory neurons that are responsive to DEET, called ADL neurons. Mis-expression of str-217 in another chemosensory neuron conferred responses to DEET. Engineered str-217 mutants, and a wild isolate of C. elegans that carries a str-217 deletion, are resistant to DEET. We found that DEET can interfere with behaviour by inducing an increase in average pause length during locomotion, and show that this increase in pausing requires both str-217 and ADL neurons. Finally, we demonstrated that ADL neurons are activated by DEET and that optogenetic activation of ADL neurons increased average pause length. This is consistent with the 'confusant' hypothesis, which proposes that DEET is not a simple repellent but that it instead modulates multiple olfactory pathways to scramble behavioural responses10,11. Our results suggest a consistent motif in the effectiveness of DEET across widely divergent taxa: an effect on multiple chemosensory neurons that disrupts the pairing between odorant stimulus and behavioural response.
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Affiliation(s)
- Emily J Dennis
- Laboratory of Neurogenetics and Behaviour, The Rockefeller University, New York, NY, USA
| | - May Dobosiewicz
- Lulu and Anthony Wang Laboratory of Neural Circuits and Behaviour, The Rockefeller University, New York, NY, USA
| | - Xin Jin
- Lulu and Anthony Wang Laboratory of Neural Circuits and Behaviour, The Rockefeller University, New York, NY, USA.,Society of Fellows, Harvard University, Cambridge, MA, USA
| | - Laura B Duvall
- Laboratory of Neurogenetics and Behaviour, The Rockefeller University, New York, NY, USA
| | - Philip S Hartman
- Department of Biology, Texas Christian University, Fort Worth, TX, USA
| | - Cornelia I Bargmann
- Lulu and Anthony Wang Laboratory of Neural Circuits and Behaviour, The Rockefeller University, New York, NY, USA.,Kavli Neural Systems Institute, New York, NY, USA
| | - Leslie B Vosshall
- Laboratory of Neurogenetics and Behaviour, The Rockefeller University, New York, NY, USA. .,Kavli Neural Systems Institute, New York, NY, USA. .,Howard Hughes Medical Institute, New York, NY, USA.
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16
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Muema JM, Bargul JL, Njeru SN, Onyango JO, Imbahale SS. Prospects for malaria control through manipulation of mosquito larval habitats and olfactory-mediated behavioural responses using plant-derived compounds. Parasit Vectors 2017; 10:184. [PMID: 28412962 PMCID: PMC5392979 DOI: 10.1186/s13071-017-2122-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 03/29/2017] [Indexed: 11/14/2022] Open
Abstract
Malaria presents an overwhelming public health challenge, particularly in sub-Saharan Africa where vector favourable conditions and poverty prevail, potentiating the disease burden. Behavioural variability of malaria vectors poses a great challenge to existing vector control programmes with insecticide resistance already acquired to nearly all available chemical compounds. Thus, approaches incorporating plant-derived compounds to manipulate semiochemical-mediated behaviours through disruption of mosquito olfactory sensory system have considerably gained interests to interrupt malaria transmission cycle. The combination of push-pull methods and larval control have the potential to reduce malaria vector populations, thus minimising the risk of contracting malaria especially in resource-constrained communities where access to synthetic insecticides is a challenge. In this review, we have compiled information regarding the current status of knowledge on manipulation of larval ecology and chemical-mediated behaviour of adult mosquitoes with plant-derived compounds for controlling mosquito populations. Further, an update on the current advancements in technologies to improve longevity and efficiency of these compounds for field applications has been provided.
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Affiliation(s)
- Jackson M Muema
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.
| | - Joel L Bargul
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.,Molecular Biology and Bioinformatics Unit, International Centre of Insect Physiology and Ecology, P.O. Box 30772-00100, Nairobi, Kenya
| | - Sospeter N Njeru
- Department of Medicine, Faculty of Health Sciences, Kisii University, P.O. Box 408-40200, Kisii, Kenya.,Present Address: Fritz Lipmann Institute (FLI) - Leibniz Institute of Aging Research, D-07745, Jena, Germany
| | - Joab O Onyango
- Department of Chemical Science and Technology, Technical University of Kenya, P.O. Box 52428-00200, Nairobi, Kenya
| | - Susan S Imbahale
- Department of Applied and Technical Biology, Technical University of Kenya, P.O. Box 52428-00200, Nairobi, Kenya
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17
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Wang P, Xu X, Liao S, Song J, Fan G, Chen S, Wang Z. Quantitative structure-activity relationship study of amide mosquito repellents. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2017; 28:341-353. [PMID: 28521600 DOI: 10.1080/1062936x.2017.1320585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 04/14/2017] [Indexed: 06/07/2023]
Abstract
A quantitative structure-activity relationship (QSAR) study on 43 amide repellents was carried out by the heuristic method in order to reveal the correlations between molecular parameters of these amides and their repellency against Aedes aegypti. Sketches and optimizations of molecular structures were achieved by the Gaussian software package. Generation and screening of molecular parameters were accomplished using CODESSA 2.7.10 software. The leave-one-out method was applied for the model validation. The results showed that a four-descriptor QSAR model with r2 of 0.897 was obtained. The average r2 values of the training set and test set of the QSAR model were 0.901 and 0.863, respectively, which suggested that the stability and predictability of the model were confirmed. Analysis of the implications of the descriptors that constitute the QSAR model indicated that all the descriptors were related to the charge distribution over the molecule and affect the dipole moment of the repellents.
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Affiliation(s)
- P Wang
- a College of Forestry, Jiangxi Agricultural University, Camphor Tree Engineering and Technology Research Center of State Forestry Administration and Jiangxi Province , Nanchang , China
| | - X Xu
- a College of Forestry, Jiangxi Agricultural University, Camphor Tree Engineering and Technology Research Center of State Forestry Administration and Jiangxi Province , Nanchang , China
| | - S Liao
- a College of Forestry, Jiangxi Agricultural University, Camphor Tree Engineering and Technology Research Center of State Forestry Administration and Jiangxi Province , Nanchang , China
| | - J Song
- b Department of Chemistry and Biochemistry , University of Michigan-Flint , Flint , MI , USA
| | - G Fan
- a College of Forestry, Jiangxi Agricultural University, Camphor Tree Engineering and Technology Research Center of State Forestry Administration and Jiangxi Province , Nanchang , China
| | - S Chen
- a College of Forestry, Jiangxi Agricultural University, Camphor Tree Engineering and Technology Research Center of State Forestry Administration and Jiangxi Province , Nanchang , China
| | - Z Wang
- a College of Forestry, Jiangxi Agricultural University, Camphor Tree Engineering and Technology Research Center of State Forestry Administration and Jiangxi Province , Nanchang , China
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18
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Norris EJ, Coats JR. Current and Future Repellent Technologies: The Potential of Spatial Repellents and Their Place in Mosquito-Borne Disease Control. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14020124. [PMID: 28146066 PMCID: PMC5334678 DOI: 10.3390/ijerph14020124] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/19/2017] [Accepted: 01/22/2017] [Indexed: 12/31/2022]
Abstract
Every year, approximately 700,000 people die from complications associated with etiologic disease agents transmitted by mosquitoes. While insecticide-based vector control strategies are important for the management of mosquito-borne diseases, insecticide-resistance and other logistical hurdles may lower the efficacy of this approach, especially in developing countries. Repellent technologies represent another fundamental aspect of preventing mosquito-borne disease transmission. Among these technologies, spatial repellents are promising alternatives to the currently utilized contact repellents and may significantly aid in the prevention of mosquito-borne disease if properly incorporated into integrated pest management approaches. As their deployment would not rely on prohibitively expensive or impractical novel accessory technologies and resources, they have potential utility in developing countries where the burden of mosquito-borne disease is most prevalent. This review aims to describe the history of various repellent technologies, highlight the potential of repellent technologies in preventing the spread of mosquito-borne disease, and discuss currently known mechanisms that confer resistance to current contact and spatial repellents, which may lead to the failures of these repellents. In the subsequent section, current and future research projects aimed at exploring long-lasting non-pyrethroid spatial repellent molecules along with new paradigms and rationale for their development will be discussed.
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Affiliation(s)
- Edmund J Norris
- Department of Entomology, Iowa State University, Ames, IA 50011, USA.
| | - Joel R Coats
- Department of Entomology, Iowa State University, Ames, IA 50011, USA.
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19
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Tisgratog R, Kongmee M, Sanguanpong U, Prabaripai A, Bangs MJ, Chareonviriyaphap T. Evaluation of a Noncontact, Alternative Mosquito Repellent Assay System. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2016; 32:177-184. [PMID: 27802399 DOI: 10.2987/16-6567.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A novel noncontact repellency assay system (NCRAS) was designed and evaluated as a possible alternative method for testing compounds that repel or inhibit mosquitoes from blood feeding. Deet and Aedes aegypti were used in a controlled laboratory setting. Using 2 study designs, a highly significant difference were seen between deet-treated and untreated skin placed behind the protective screens, indicating that deet was detected and was acting as a deterrence to mosquito landing and probing behavior. However, a 2nd study showed significant differences between protected (behind a metal screen barrier) and unprotected (exposed) deet-treated forearms, indicating the screen mesh might restrict the detection of deet and thus influences landing/biting response. These findings indicate the prototype NCRAS shows good promise but requires further evaluation and possible modification in design and testing protocol to achieve more desirable operational attributes in comparison with direct skin-contact repellency mosquito assays.
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21
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DEET (N,N-diethyl-meta-toluamide)/PMD (para-menthane-3,8-diol) repellent-treated mesh increases Culicoides catches in light traps. Parasitol Res 2016; 115:3543-9. [DOI: 10.1007/s00436-016-5119-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/04/2016] [Indexed: 11/24/2022]
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22
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Sugiharto VA, Murphy JR, Turell MJ, Olsen CH, Stewart VA, Colacicco-Mayhugh MG, Grieco JP, Achee NL. Dengue Virus-1 Infection Did Not Alter the Behavioral Response of Aedes aegypti (Diptera: Culicidae) to DEET. JOURNAL OF MEDICAL ENTOMOLOGY 2016; 53:687-691. [PMID: 27026163 DOI: 10.1093/jme/tjw030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 02/26/2016] [Indexed: 06/05/2023]
Abstract
No licensed vaccine or antiviral drug against dengue virus (DENV) is available; therefore, most of the effort to prevent this disease is focused on reducing vector-host interactions. One of the most widely accepted methods of blocking vector-human contact is to use insect repellents to interfere with mosquito host-seeking behavior. Some arboviruses can replicate in the nervous system of the vector, raising the concern that arboviral infection may alter the insect behavioral response toward chemical stimuli. Three different Aedes aegypti (L.) mosquito cohorts: DENV-1-injected, diluent-injected, and uninjected were subjected to behavioral tests using a high-throughput screening system with 2.5% DEET and 0.14% DEET on 1, 4, 7, 10, 14, and 17 d postinjection. All test cohorts exhibited significant contact irritant or escape responses when they were exposed to 2.5% or 0.14% DEET. However, we found no biologically relevant irritancy response change in DENV-1-infected Ae. aegypti mosquitoes when they were exposed to DEET. Further studies evaluating the effects of other arboviral infections on insect repellents activity are necessary in order to provide better recommendation on the prevention of vector-borne disease transmission.
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Affiliation(s)
- Victor A Sugiharto
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; ),
| | - Jittawadee R Murphy
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
| | - Michael J Turell
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
| | - Cara H Olsen
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
| | - V Ann Stewart
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
| | - Michelle G Colacicco-Mayhugh
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
| | - John P Grieco
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
| | - Nicole L Achee
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
- Department of Preventive Medicine & Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 (; ; ; ; ; )
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23
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Campos D, Gravato C, Quintaneiro C, Soares AMVM, Pestana JLT. Responses of the aquatic midge Chironomus riparius to DEET exposure. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 172:80-85. [PMID: 26773354 DOI: 10.1016/j.aquatox.2015.12.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/18/2015] [Accepted: 12/29/2015] [Indexed: 06/05/2023]
Abstract
N,N-diethyl-3-methylbenzamide (DEET) is the active ingredient of many commercial insect repellents. Despite being detected worldwide in effluents, surface water and groundwater, there is still limited information on DEET's toxicity toward non-target aquatic invertebrates. Thus, our main objective was to assess the effects of DEET in the life cycle of Chironomus riparius and assess its biochemical effects. Laboratory assays showed that DEET reduced developmental rates (reduced larval growth, delayed emergence) of C. riparius larvae and also caused a decrease in the size of adult midges. Concerning the biochemical responses, a short exposure to DEET caused no effects in lipid peroxidation, despite the significant inhibition of catalase and glutathione-S-transferase activities and of total glutathione contents. Moreover, inhibition of acetylcholinesterase activity was also observed showing neurotoxic effects. Environmental risk assessment of insect repellents is needed. Our results showed moderate toxicity of DEET toward C. riparius, however, due to their mode of action, indirect ecological effects of DEET and of other insect repellents cannot be excluded and should be evaluated.
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Affiliation(s)
- Diana Campos
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Carlos Gravato
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Carla Quintaneiro
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Amadeu M V M Soares
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - João L T Pestana
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
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Malengier B, Goessens T, Mafo FF, De Vrieze M, Van Langenhove L, Wanji S, Lynen F. Model-based determination of the influence of textile fabric on bioassay analysis and the effectiveness of a textile slow-release system of DEET in mosquito control. PEST MANAGEMENT SCIENCE 2015; 71:1165-1174. [PMID: 25200386 DOI: 10.1002/ps.3902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 08/29/2014] [Accepted: 09/02/2014] [Indexed: 06/03/2023]
Abstract
BACKGROUND Determining the effectiveness of a product in repelling mosquitoes or other flying insects is a difficult task. One approach is to use a bioassay with textile fabric. We investigated the role of the textile substrate in a bioassay with a numerical model, and compared the outcome with known results for DEET. The model was then used to determine the effectiveness of textile slow-release formulations based on coatings, and results were compared with those of a field study in the Cameroon. Slow-release formulations are difficult to evaluate with standard tests, as the compound needs a build-up time not present in these tests. RESULTS We found excellent correspondence between the model and the known DEET results without matching parameters. Slow-release approaches are deemed possible but have several drawbacks. Modelling can help in identifying optimal use conditions. The field test with a slow-release system performed better than anticipated by the model, with initially more than 90% repellency. DEET-coated textile was considered not to be marketable, however. CONCLUSION We advise that bioassays characterise in more detail the type of textile fabric used so as to allow conclusions to be drawn by textile modelling. As regards coated-textile slow-release systems, more research is needed. We nevertheless advise usage mainly at entry points, e.g. as scrims.
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Affiliation(s)
- Benny Malengier
- Department of Textiles, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Tineke Goessens
- Research Group for Numerical Analysis and Mathematical Modelling, Department of Mathematical Analysis, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Flora F Mafo
- University of Yaoundé I, Yaoundé, Cameroon
- Research Foundation for Tropical Diseases and Environment, University of Buea, Buea, Cameroon
| | - Mike De Vrieze
- Department of Organic Chemistry, Faculty of Science, Ghent University, Ghent, Belgium
| | - Lieva Van Langenhove
- Department of Textiles, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Samuel Wanji
- Research Foundation for Tropical Diseases and Environment, University of Buea, Buea, Cameroon
| | - Frederic Lynen
- Department of Organic Chemistry, Faculty of Science, Ghent University, Ghent, Belgium
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Owino EA, Sang R, Sole CL, Pirk C, Mbogo C, Torto B. An improved odor bait for monitoring populations of Aedes aegypti-vectors of dengue and chikungunya viruses in Kenya. Parasit Vectors 2015; 8:253. [PMID: 25924877 PMCID: PMC4418051 DOI: 10.1186/s13071-015-0866-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 04/10/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Effective surveillance and estimation of the biting fraction of Aedes aegypti is critical for accurate determination of the extent of virus transmission during outbreaks and inter-epidemic periods of dengue and chikungunya fever. Here, we describe the development and use of synthetic human odor baits for improved sampling of adult Ae. aegypti, in two dengue and chikungunya fevers endemic areas in Kenya; Kilifi and Busia counties. METHODS We collected volatiles from the feet and trunks of two female and two male volunteers aged between 25 and 45 years. We used coupled gas chromatography- electroantennographic detection (GC/EAD) analysis to screen for antennally-active components from the volatiles and coupled GC-mass spectrometry (GC/MS) to identify the EAD-active components. Using randomized replicated designs, we compared the efficacies of Biogents (BG) sentinel traps baited with carbon dioxide plus either single or blends of the identified compounds against the BG sentinel trap baited with carbon dioxide plus the BG commercial lure in trapping Ae. aegypti. The daily mosquito counts in the different traps were subjected to negative binomial regression following the generalized linear models procedures. RESULTS A total of ten major EAD-active components identified by GC/MS as mainly aldehydes and carboxylic acids, were consistently isolated from the human feet and trunk volatiles from at least two volunteers. Field assays with synthetic chemicals of the shared EAD-active components identified from the feet and trunk gave varying results. Ae. aegypti were more attracted to carbon dioxide baited BG sentinel traps combined with blends of aldehydes than to similar traps combined with blends of carboxylic acids. When we assessed the efficacy of hexanoic acid detected in odors of the BG commercial lure and volunteers plus carbon dioxide, trap captures of Ae. aegypti doubled over the trap baited with the commercial BG lure. However, dispensing aldehydes and carboxylic acids together in blends, reduced trap captures of Ae. aegypti by ~45%-50%. CONCLUSIONS Our results provide evidence for roles of carboxylic acids and aldehydes in Ae. aegypti host attraction and also show that of the carboxylic acids, hexanoic acid is a more effective lure for the vector than the BG commercial lure.
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Affiliation(s)
- Eunice A Owino
- International Centre of Insect Physiology and Ecology, P.O BOX 30772-00100, Nairobi, Kenya, Africa.
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa.
| | - Rosemary Sang
- International Centre of Insect Physiology and Ecology, P.O BOX 30772-00100, Nairobi, Kenya, Africa.
| | - Catherine L Sole
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa.
| | - Christian Pirk
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa.
| | - Charles Mbogo
- Centre for Geographic Medicine Research - Coast, KEMRI & KEMRI - Wellcome Trust Research Programme, Kilifi, Kenya.
| | - Baldwyn Torto
- International Centre of Insect Physiology and Ecology, P.O BOX 30772-00100, Nairobi, Kenya, Africa.
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Tsitoura P, Koussis K, Iatrou K. Inhibition of Anopheles gambiae odorant receptor function by mosquito repellents. J Biol Chem 2015; 290:7961-72. [PMID: 25657000 PMCID: PMC4367294 DOI: 10.1074/jbc.m114.632299] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/28/2015] [Indexed: 11/06/2022] Open
Abstract
The identification of molecular targets of insect repellents has been a challenging task, with their effects on odorant receptors (ORs) remaining a debatable issue. Here, we describe a study on the effects of selected mosquito repellents, including the widely used repellent N,N-diethyl-meta-toluamide (DEET), on the function of specific ORs of the African malaria vector Anopheles gambiae. This study, which has been based on quantitative measurements of a Ca(2+)-activated photoprotein biosensor of recombinant OR function in an insect cell-based expression platform and a sequential compound addition protocol, revealed that heteromeric OR (ORx/Orco) function was susceptible to strong inhibition by all tested mosquito repellents except DEET. Moreover, our results demonstrated that the observed inhibition was due to efficient blocking of Orco (olfactory receptor coreceptor) function. This mechanism of repellent action, which is reported for the first time, is distinct from the mode of action of other characterized insect repellents including DEET.
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Affiliation(s)
- Panagiota Tsitoura
- From the Insect Molecular Genetics and Biotechnology Group, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", 15310 Athens and
| | - Konstantinos Koussis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Crete, Greece
| | - Kostas Iatrou
- From the Insect Molecular Genetics and Biotechnology Group, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", 15310 Athens and
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27
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DeGennaro M. The mysterious multi-modal repellency of DEET. Fly (Austin) 2015; 9:45-51. [PMID: 26252744 PMCID: PMC4594586 DOI: 10.1080/19336934.2015.1079360] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/03/2015] [Accepted: 07/20/2015] [Indexed: 01/01/2023] Open
Abstract
DEET is the most effective insect repellent available and has been widely used for more than half a century. Here, I review what is known about the olfactory and contact mechanisms of DEET repellency. For mosquitoes, DEET has at least two molecular targets: Odorant Receptors (ORs) mediate the effect of DEET at a distance, while unknown chemoreceptors mediate repellency upon contact. Additionally, the ionotropic receptor Ir40a has recently been identified as a putative DEET chemosensor in Drosophila. The mechanism of how DEET manipulates these molecular targets to induce insect avoidance in the vapor phase is also contested. Two hypotheses are the most likely: DEET activates an innate olfactory neural circuit leading to avoidance of hosts (smell and avoid hypothesis) or DEET has no behavioral effect on its own, but instead acts cooperatively with host odors to drive repellency (confusant hypothesis). Resolving this mystery will inform the search for a new generation of insect repellents.
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Affiliation(s)
- Matthew DeGennaro
- Biomolecular Sciences Institute & Department of Biological Sciences; Florida International University; Miami, FL USA
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28
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Menger DJ, Van Loon JJA, Takken W. Assessing the efficacy of candidate mosquito repellents against the background of an attractive source that mimics a human host. MEDICAL AND VETERINARY ENTOMOLOGY 2014; 28:407-413. [PMID: 24797537 DOI: 10.1111/mve.12061] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/11/2014] [Accepted: 02/17/2014] [Indexed: 06/03/2023]
Abstract
Mosquito repellents are used around the globe to protect against nuisance biting and disease-transmitting mosquitoes. Recently, there has been renewed interest in the development of repellents as tools to control the transmission of mosquito-borne diseases. We present a new bioassay for the accurate assessment of candidate repellent compounds, using a synthetic odour that mimics the odour blend released by human skin. Using DEET (N,N-diethyl-meta-toluamide) and PMD (p-menthane-3,8-diol) as reference compounds, nine candidate repellents were tested, of which five showed significant repellency to the malaria mosquito Anopheles gambiae sensu stricto (Diptera: Culicidae). These included: 2-nonanone; 6-methyl-5-hepten-2-one; linalool; δ-decalactone, and δ-undecalactone. The lactones were also tested on the yellow fever mosquito Aedes aegypti (Stegomyia aegypti) (Diptera: Culicidae), against which they showed similar degrees of repellency. We conclude that the lactones are highly promising repellents, particularly because these compounds are pleasant-smelling, natural products that are also present in human food sources.
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Affiliation(s)
- D J Menger
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, the Netherlands
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29
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Liao S, Song J, Wang Z, Chen J, Fan G, Song Z, Shang S, Chen S, Wang P. Molecular interactions between terpenoid mosquito repellents and human-secreted attractants. Bioorg Med Chem Lett 2014; 24:773-9. [DOI: 10.1016/j.bmcl.2013.12.102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 12/20/2013] [Accepted: 12/24/2013] [Indexed: 10/25/2022]
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Fabbro SD, Nazzi F. From Chemistry to Behavior. Molecular Structure and Bioactivity of Repellents against Ixodes ricinus Ticks. PLoS One 2013; 8:e67832. [PMID: 23805329 PMCID: PMC3689731 DOI: 10.1371/journal.pone.0067832] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 05/22/2013] [Indexed: 11/19/2022] Open
Abstract
Tick-borne zoonoses are considered as emerging diseases. Tick repellents represent an effective tool for reducing the risk of tick bite and pathogens transmission. Previous work demonstrated the repellent activity of the phenylpropanoid eugenol against Ixodes ricinus; here we investigate the relationship between molecular structure and repellency in a group of substances related to that compound. We report the biological activity of 18 compounds varying for the presence/number of several moieties, including hydroxyl and methoxy groups and carbon side-chain. Each compound was tested at different doses with a bioassay designed to measure repellency against individual tick nymphs. Both vapor pressure and chemical features of the tested compounds appeared to be related to repellency. In particular, the hydroxyl and methoxy groups as well as the side-chain on the benzene ring seem to play a role. These results are discussed in light of available data on chemical perception in ticks. In the course of the study new repellent compounds were identified; the biological activity of some of them (at least as effective as the “gold standard” repellent DEET) appears to be very promising from a practical point of view.
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Affiliation(s)
- Simone Del Fabbro
- Dipartimento di Scienze Agrarie e Ambientali, Università degli Studi di Udine, Udine, Italy
- * E-mail:
| | - Francesco Nazzi
- Dipartimento di Scienze Agrarie e Ambientali, Università degli Studi di Udine, Udine, Italy
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orco mutant mosquitoes lose strong preference for humans and are not repelled by volatile DEET. Nature 2013; 498:487-91. [PMID: 23719379 PMCID: PMC3696029 DOI: 10.1038/nature12206] [Citation(s) in RCA: 294] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 04/19/2013] [Indexed: 11/18/2022]
Abstract
Female mosquitoes of some species are generalists and will blood-feed on a variety of vertebrate hosts, whereas others display marked host preference. Anopheles gambiae and Aedes aegypti have evolved a strong preference for humans, making them dangerously efficient vectors of malaria and Dengue haemorrhagic fever1. Specific host odours likely drive this strong preference since other attractive cues, including body heat and exhaled carbon dioxide (CO2) are common to all warm-blooded hosts2, 3. Insects sense odours via several chemosensory receptor families, including the odorant receptors (ORs). ORs are membrane proteins that form heteromeric odour-gated ion channels4, 5 comprised of a variable ligand-selective subunit and an obligate co-receptor called Orco6. Here we use zinc-finger nucleases to generate targeted mutations in the Ae. aegypti orco gene to examine the contribution of Orco and the OR pathway to mosquito host selection and sensitivity to the insect repellent DEET. orco mutant olfactory sensory neurons have greatly reduced spontaneous activity and lack odour-evoked responses. Behaviourally, orco mutant mosquitoes have severely reduced attraction to honey, an odour cue related to floral nectar, and do not respond to human scent in the absence of CO2. However, in the presence of CO2, female orco mutant mosquitoes retain strong attraction to both human and animal hosts, but no longer strongly prefer humans. orco mutant females are attracted to human hosts even in the presence of DEET, but are repelled upon contact, indicating that olfactory- and contact-mediated effects of DEET are mechanistically distinct. We conclude that the OR pathway is crucial for an anthropophilic vector mosquito to discriminate human from non-human hosts and to be effectively repelled by volatile DEET.
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Song J, Wang Z, Findlater A, Han Z, Jiang Z, Chen J, Zheng W, Hyde S. Terpenoid mosquito repellents: a combined DFT and QSAR study. Bioorg Med Chem Lett 2013; 23:1245-8. [PMID: 23375229 DOI: 10.1016/j.bmcl.2013.01.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 12/20/2012] [Accepted: 01/02/2013] [Indexed: 10/27/2022]
Abstract
Interactions between low-toxicity terpenoid mosquito repellents and lactic acid are studied at the HF and B3LYP level. The subsequent QSAR study shows that not only the structure of repellents but also the repellent-lactic acid complexes may play an important role. It suggests that further study on interactions between repellents and characteristic compounds from human host may be required in order to understand the repelling mechanism.
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Affiliation(s)
- Jie Song
- Department of Chemistry, University of Michigan-Flint, 303E Kearsley, Flint, MI 48502, United States.
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Tananchai C, Tisgratog R, Grieco JP, Chareonviriyaphap T. Pyrethroid induced behavioral responses of Anopheles dirus, a vector of malaria in Thailand. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2012; 37:187-196. [PMID: 22548553 DOI: 10.1111/j.1948-7134.2012.00216.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Contact and noncontact behavioral actions of wild-caught Anopheles dirus in response to the operational field dose of three synthetic pyrethroids (bifenthrin, α-cypermethrin and λ-cyhalothrin) were evaluated using an exito-repellency test chamber. DEET was used as the repellency standard for comparison with the other three synthetic pyrethroids. Results showed that test specimens rapidly escaped from the test chamber when exposed to direct contact with a surface treated with each of the three synthetic pyrethroids and DEET. Alpha-cypermethrin demonstrated the strongest irritant action (84.9% escape), followed by DEET (77.0%), λ-cyhalothrin (68.6%) and bifenthrin (68.3%). In the noncontact configuration, fewer mosquitoes escaped from the test chambers as compared to contact trials, although a significant escape response was still observed as compared to the controls (P<0.05). We conclude that An. dirus exhibits both irritant and repellent actions in response the three pyrethroids testing in this study. The information obtained will allow us to better understand the behavioral responses of vectors to various chemicals and provide guidance when designing control strategies for targeting specific disease vectors.
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Affiliation(s)
- Chatchai Tananchai
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
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34
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Shelomi M, Matern LM, Dinstell JM, Harris DW, Kimsey RB. DEET (N,N-diethyl-meta-toluamide) induced delay of blowfly landing and oviposition rates on treated pig carrion (Sus scrofa L.). J Forensic Sci 2012; 57:1507-11. [PMID: 22515377 DOI: 10.1111/j.1556-4029.2012.02159.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The question of whether the insect repellent N,N-Diethyl-meta-toluamide (DEET) affected fly attraction, oviposition, and larval development was investigated; in part, to determine whether the common habit of wearing DEET as a repellent could affect the rate of human decomposition. Experiments using pig surrogates of human decedents were carried out in a rural environment. Dead piglets were sprayed with DEET, and fly behavior, colonization levels, and maggot development were compared with those in nonsprayed controls. Piglets treated with DEET experienced significant delays in fly visitation and oviposition and delayed appearance of each larval instar, as well as reduced total larval numbers (p < 0.01 for all variables), with subsequently reduced decomposition (p < 0.05). Such changes in fly behavior and larval population development would significantly impact the estimation of the period following the death from entomological evidence in decedents wearing DEET at the time of their death.
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Affiliation(s)
- Matan Shelomi
- Department of Entomology, University of California-Davis, Davis, CA 95616, USA.
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35
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Odorant receptor modulation: Ternary paradigm for mode of action of insect repellents. Neuropharmacology 2012; 62:2086-95. [DOI: 10.1016/j.neuropharm.2012.01.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 12/12/2011] [Accepted: 01/09/2012] [Indexed: 11/18/2022]
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36
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Tsitsanou KE, Thireou T, Drakou CE, Koussis K, Keramioti MV, Leonidas DD, Eliopoulos E, Iatrou K, Zographos SE. Anopheles gambiae odorant binding protein crystal complex with the synthetic repellent DEET: implications for structure-based design of novel mosquito repellents. Cell Mol Life Sci 2012; 69:283-97. [PMID: 21671117 PMCID: PMC11114729 DOI: 10.1007/s00018-011-0745-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/26/2011] [Accepted: 05/30/2011] [Indexed: 10/18/2022]
Abstract
Insect odorant binding proteins (OBPs) are the first components of the olfactory system to encounter and bind attractant and repellent odors emanating from various sources for presentation to olfactory receptors, which trigger relevant signal transduction cascades culminating in specific physiological and behavioral responses. For disease vectors, particularly hematophagous mosquitoes, repellents represent important defenses against parasitic diseases because they effect a reduction in the rate of contact between the vectors and humans. OBPs are targets for structure-based rational approaches for the discovery of new repellent or other olfaction inhibitory compounds with desirable features. Thus, a study was conducted to characterize the high resolution crystal structure of an OBP of Anopheles gambiae, the African malaria mosquito vector, in complex with N,N-diethyl-m-toluamide (DEET), one of the most effective repellents that has been in worldwide use for six decades. We found that DEET binds at the edge of a long hydrophobic tunnel by exploiting numerous non-polar interactions and one hydrogen bond, which is perceived to be critical for DEET's recognition. Based on the experimentally determined affinity of AgamOBP1 for DEET (K (d) of 31.3 μΜ) and our structural data, we modeled the interactions for this protein with 29 promising leads reported in the literature to have significant repellent activities, and carried out fluorescence binding studies with four highly ranked ligands. Our experimental results confirmed the modeling predictions indicating that structure-based modeling could facilitate the design of novel repellents with enhanced binding affinity and selectivity.
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Affiliation(s)
- K. E. Tsitsanou
- Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 11635 Athens, Greece
| | - T. Thireou
- Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece
| | - C. E. Drakou
- Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 11635 Athens, Greece
| | - K. Koussis
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, NCSR “Demokritos”, Agia Paraskevi, 15310 Athens, Greece
| | - M. V. Keramioti
- Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 11635 Athens, Greece
| | - D. D. Leonidas
- Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece
| | - E. Eliopoulos
- Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece
| | - K. Iatrou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, NCSR “Demokritos”, Agia Paraskevi, 15310 Athens, Greece
| | - S. E. Zographos
- Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 11635 Athens, Greece
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Tisgratog R, Tananchai C, Bangs MJ, Tainchum K, Juntarajumnong W, Prabaripai A, Chauhan KR, Pothikasikorn J, Chareonviriyaphap T. Chemically induced behavioral responses in Anopheles minimus and Anopheles harrisoni in Thailand. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2011; 36:321-331. [PMID: 22129403 DOI: 10.1111/j.1948-7134.2011.00172.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Behavioral responses of female mosquitoes representing two species in the Minimus Complex exposed to an operational field dose of bifenthrin or DEET (N,N-diethyl-m-toluamide) were described using an excito-repellency test system. Two test populations of An. minimus, one from the field (Tak Province, western Thailand), the other from a long-established laboratory colony, and Anopheles harrisoni collected from Kanchanaburi Province, western Thailand, were used. Results showed that all test populations rapidly escaped after direct contact with surfaces treated with either bifenthrin or DEET compared to match-paired untreated controls. Greater escape response by exposed females to bifenthrin and DEET were observed in the An. minimus colony compared to the two field populations. Field-collected An. minimus demonstrated a more rapid escape response to DEET than to bifenthrin, whereas An. harrisoni showed a converse response. Although fewer females escaped from test chambers without direct contact with treated surfaces compared to contact tests, the spatial repellency response was significantly pronounced in all test populations compared to match-paired controls (P < 0.05). DEET was found to perform as both a contact stimulant and moderate spatial repellent.
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Affiliation(s)
- Rungarun Tisgratog
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
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38
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Sfara V, Mougabure-Cueto G, Zerba EN, Alzogaray RA. Adaptation of the repellency response to DEET in Rhodnius prolixus. JOURNAL OF INSECT PHYSIOLOGY 2011; 57:1431-1436. [PMID: 21801727 DOI: 10.1016/j.jinsphys.2011.07.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 07/08/2011] [Accepted: 07/13/2011] [Indexed: 05/31/2023]
Abstract
For many years it has been accepted that DEET interferes with the detection of odours from the host instead of having a repellent effect. However, recent work showed that DEET acts as an odorant molecule and elicits a behavioural response in the absence of other stimuli. Therefore, DEET must promote some phenomenon connected with the stimuli-sensory system interaction, such as a sensory adaptation, where the sensory system regulates its sensitivity to different stimuli intensities during continuous or repetitive exposure. In this work, we studied different aspects of the insect-DEET interaction through behavioural observations. Previous exposure of fifth instar Rhodnius prolixus nymphs to DEET decreased the behavioural response to this repellent. We observed a decrease in repellence after different times of continuous stimulation with DEET in a time-dependent manner. The response to DEET was recovered 10 min after exposure, when insects were continuously stimulated during 5 or 10 min; maximum repellence was recovered 20 min after exposure when insects were stimulated for 20 min. DEET produced a repellent effect when nymphs were exposed only to its vapours. These results suggest that exposure to DEET produces adaptation in R. prolixus nymphs, and that the behavioural response elicited by DEET occurs via olfaction when no other stimuli are present.
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Affiliation(s)
- Valeria Sfara
- Centro de Investigaciones de Plagas e Insecticidas (CONICET), Juan Bautista de La Salle 4397, Buenos Aires, Argentina.
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39
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A natural polymorphism alters odour and DEET sensitivity in an insect odorant receptor. Nature 2011; 478:511-4. [PMID: 21937991 PMCID: PMC3203342 DOI: 10.1038/nature10438] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 08/08/2011] [Indexed: 02/03/2023]
Abstract
Blood-feeding insects such as mosquitoes are efficient vectors of human infectious diseases because they are strongly attracted by body heat, carbon dioxide and odours produced by their vertebrate hosts. Insect repellents containing DEET (N,N-diethyl-meta-toluamide) are highly effective, but the mechanism by which this chemical wards off biting insects remains controversial despite decades of investigation. DEET seems to act both at close range as a contact chemorepellent, by affecting insect gustatory receptors, and at long range, by affecting the olfactory system. Two opposing mechanisms for the observed behavioural effects of DEET in the gas phase have been proposed: that DEET interferes with the olfactory system to block host odour recognition and that DEET actively repels insects by activating olfactory neurons that elicit avoidance behaviour. Here we show that DEET functions as a modulator of the odour-gated ion channel formed by the insect odorant receptor complex. The functional insect odorant receptor complex consists of a common co-receptor, ORCO (ref. 15) (formerly called OR83B; ref. 16), and one or more variable odorant receptor subunits that confer odour selectivity. DEET acts on this complex to potentiate or inhibit odour-evoked activity or to inhibit odour-evoked suppression of spontaneous activity. This modulation depends on the specific odorant receptor and the concentration and identity of the odour ligand. We identify a single amino-acid polymorphism in the second transmembrane domain of receptor OR59B in a Drosophila melanogaster strain from Brazil that renders OR59B insensitive to inhibition by the odour ligand and modulation by DEET. Our data indicate that natural variation can modify the sensitivity of an odour-specific insect odorant receptor to odour ligands and DEET. Furthermore, they support the hypothesis that DEET acts as a molecular 'confusant' that scrambles the insect odour code, and provide a compelling explanation for the broad-spectrum efficacy of DEET against multiple insect species.
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40
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Choi MR, Kim SY, Choi JH, Park SH, Yong CS, Kim JS. Temperature and pH Stability Profiles of ortho and para DEET. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2011. [DOI: 10.4333/kps.2011.41.4.233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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41
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Abstract
DEET is the most widely used insect repellent worldwide. In Drosophila olfactory receptor neurons (ORNs), DEET is detected through a mechanism employing the olfactory receptor, OR83b. However, it is controversial as to whether ORNs respond directly to DEET or whether DEET blocks the response to attractive odors. Here, we showed that DEET suppressed feeding behavior in Drosophila, and this effect was mediated by gustatory receptor neurons (GRNs). DEET was potent in suppressing feeding as <0.1% DEET elicited aversive behavior. Inhibition of feeding required multiple gustatory receptors (GRs) expressed in inhibitory GRNs. DEET stimulated action potentials in GRNs that respond to aversive compounds, and this response was lost in the Gr32a, Gr33a, and Gr66a mutants. Since 0.02% DEET elicited action potentials, we conclude that DEET directly activates of GRNs. We suggest that the effectiveness of DEET in pest control owes to its dual action in inducing avoidance simultaneously via GRNs and ORNs.
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42
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Paluch G, Bartholomay L, Coats J. Mosquito repellents: a review of chemical structure diversity and olfaction. PEST MANAGEMENT SCIENCE 2010; 66:925-935. [PMID: 20623705 DOI: 10.1002/ps.1974] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Research on mosquito chemical repellents continues to advance, along with knowledge of mosquito olfaction and behavior, mosquito-host interactions and chemical structure. New tools and technologies have revealed information about insect olfactory mechanisms and processing, providing a more complex approach for the interpretation of how chemical repellents influence host-seeking and feeding behavior. Even with these advances, there is still a large amount of information contained in the early works on insect repellents. Many of the standard test methods and chemicals that are still used for evaluating active repellents were developed in the 1940s. These studies contain valuable references to the activity of different structural classes of chemicals, and serve as a guide to optimization of select compounds for insect repellency effects.
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Affiliation(s)
- Gretchen Paluch
- Department of Entomology, Iowa State University, Ames, IA 50011, USA
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43
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Bohbot JD, Dickens JC. Insect repellents: modulators of mosquito odorant receptor activity. PLoS One 2010; 5:e12138. [PMID: 20725637 PMCID: PMC2920324 DOI: 10.1371/journal.pone.0012138] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 07/21/2010] [Indexed: 11/18/2022] Open
Abstract
Background DEET, 2-undecanone (2-U), IR3535 and Picaridin are widely used as insect repellents to prevent interactions between humans and many arthropods including mosquitoes. Their molecular action has only recently been studied, yielding seemingly contradictory theories including odorant-dependent inhibitory and odorant-independent excitatory activities on insect olfactory sensory neurons (OSNs) and odorant receptor proteins (ORs). Methodology/Principal Findings Here we characterize the action of these repellents on two Aedes aegypti ORs, AaOR2 and AaOR8, individually co-expressed with the common co-receptor AaOR7 in Xenopus oocytes; these ORs are respectively activated by the odors indole (AaOR2) and (R)-(−)-1-octen3-ol (AaOR8), odorants used to locate oviposition sites and host animals. In the absence of odorants, DEET activates AaOR2 but not AaOR8, while 2-U activates AaOR8 but not AaOR2; IR3535 and Picaridin do not activate these ORs. In the presence of odors, DEET strongly inhibits AaOR8 but not AaOR2, while 2-U strongly inhibits AaOR2 but not AaOR8; IR3535 and Picaridin strongly inhibit both ORs. Conclusions/Significance These data demonstrate that repellents can act as olfactory agonists or antagonists, thus modulating OR activity, bringing concordance to conflicting models.
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Affiliation(s)
- Jonathan D. Bohbot
- Invasive Insect Biocontrol and Behavior Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Plant Sciences Institute, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States of America
| | - Joseph C. Dickens
- Invasive Insect Biocontrol and Behavior Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Plant Sciences Institute, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States of America
- * E-mail:
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Behavioral insensitivity to DEET in Aedes aegypti is a genetically determined trait residing in changes in sensillum function. Proc Natl Acad Sci U S A 2010; 107:8575-80. [PMID: 20439757 DOI: 10.1073/pnas.1001313107] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
N,N-Diethyl-m-toluamide (DEET) is one of the most effective and commonly used mosquito repellents. However, during laboratory trials a small proportion of mosquitoes are still attracted by human odors despite the presence of DEET. In this study behavioral assays identified Aedes aegypti females that were insensitive to DEET, and the selection of either sensitive or insensitive groups of females with males of unknown sensitivity over several generations resulted in two populations with different proportions of insensitive females. Crossing experiments showed the "insensitivity" trait to be dominant. Electroantennography showed a reduced response to DEET in the selected insensitive line compared with the selected sensitive line, and single sensillum recordings identified DEET-sensitive sensilla that were nonresponders in the insensitive line. This study suggests that behavioral insensitivity to DEET in A. aegypti is a genetically determined dominant trait and resides in changes in sensillum function.
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Jahn A, Kim SY, Choi JH, Kim DD, Ahn YJ, Yong CS, Kim JS. A bioassay for mosquito repellency against Aedes aegypti: method validation and bioactivities of DEET analogues. J Pharm Pharmacol 2010; 62:91-7. [DOI: 10.1211/jpp.62.01.0010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
Objectives
Vector-borne diseases are still a major mortality factor in Africa and South-east Asia and effective mosquito repellents are therefore needed. An efficient and safe in-vitro assay system using artificial blood and skin substitute could facilitate the development of novel repellents, as most assays currently rely on human subjects or vertebrate whole blood. Moreover, examining the skin permeation profiles could provide safer mosquito repellents. The new assay system could serve as an initial system for testing new repellent candidates upon validation with DEET and its analogues.
Methods
N,N-Diethyl-meta-toluamide (DEET) and five analogues were synthesised and used to validate a novel in-vitro bioassay using artificial blood and collagen membrane. Repellency against Aedes aegypti was correlated with lipophilicity and skin permeation.
Key findings
The new in-vitro assay showed good reproducibility (interday relative standard deviation <10% at high concentrations). Four of the five DEET analogues showed repellency similar or superior to that of DEET. Repellency correlated linearly with lipophilicity but stronger repellents tended to permeate skin better.
Conclusions
The new in-vitro assay using blood substitute and collagen membrane significantly simplifies screening of possible mosquito repellents. Lipophilicity as well as skin permeation profiles should be considered before testing of compounds that are candidates for mosquito repellents.
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Affiliation(s)
- Alexander Jahn
- Department of Biotechnology & Department of Biomedical Laboratory Science, Dongseo University, Busan, South Korea
| | - Seok Yong Kim
- Department of Biotechnology & Department of Biomedical Laboratory Science, Dongseo University, Busan, South Korea
| | - Joon-Ho Choi
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, South Korea
| | - Dae-Duk Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, South Korea
| | - Young-Joon Ahn
- School of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
| | - Chul Soon Yong
- College of Pharmacy, Yeungnam University, Gyeongsan, South Korea
| | - Jung Sun Kim
- Department of Biotechnology & Department of Biomedical Laboratory Science, Dongseo University, Busan, South Korea
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Soares SF, Borges LMF, de Sousa Braga R, Ferreira LL, Louly CCB, Tresvenzol LMF, de Paula JR, Ferri PH. Repellent activity of plant-derived compounds against Amblyomma cajennense (Acari: Ixodidae) nymphs. Vet Parasitol 2010; 167:67-73. [DOI: 10.1016/j.vetpar.2009.09.047] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 09/20/2009] [Accepted: 09/28/2009] [Indexed: 10/20/2022]
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Okumu FO, Titus E, Mbeyela E, Killeen GF, Moore SJ. Limitation of using synthetic human odours to test mosquito repellents. Malar J 2009; 8:150. [PMID: 19583848 PMCID: PMC2712479 DOI: 10.1186/1475-2875-8-150] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Accepted: 07/07/2009] [Indexed: 12/02/2022] Open
Abstract
Background Gold-standard tests of mosquito repellents involve exposing human volunteers to host-seeking mosquitoes, to assess the protective efficacy of the repellents. These techniques are not exposure-free and cannot be performed prior to toxicological evaluation. It is postulated that synthetic lures could provide a useful assay that mimics in-vivo conditions for use in high-throughput screening for mosquito repellents. Methods This paper reports on a semi-field evaluation of repellents using a synthetic blend of human derived attractants for the malaria vector, Anopheles gambiae sensu stricto Different concentrations of known repellents, N, N diethyl-3-methylbenzamide (deet) and Para-methane-3, 8, diol (PMD) were added into traps baited with the synthetic blend, and resulting changes in mosquito catches were measured. Results All test concentrations of deet (0.001% to 100%) reduced the attractiveness of the synthetic blend. However, PMD was repellent only at 0.25%. Above this concentration, it significantly increased the attractiveness of the blend. There was no relationship between the repellent concentrations and the change in mosquito catches when either deet (r2 = 0.033, P = 0.302) or PMD (r2 = 0.020, P = 0.578) was used. Conclusion It is concluded that while some repellents may reduce the attractiveness of synthetic human odours, others may instead increase their attractiveness. Such inconsistencies indicate that even though the synthetic attractants may provide exposure-free and consistent test media for repellents, careful selection and multiple-repellent tests are necessary to ascertain their suitability for use in repellent screening. The synthetic odour blend tested here is not yet sufficiently refined to serve as replacement for humans in repellent testing, but may be developed further and evaluated in different formats for exposure free repellent testing purposes.
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Affiliation(s)
- Fredros O Okumu
- Biomedical and Environmental Sciences Thematic group, Ifakara Health Institute, Ifakara, Tanzania.
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Kagle J, Porter AW, Murdoch RW, Rivera-Cancel G, Hay AG. Biodegradation of pharmaceutical and personal care products. ADVANCES IN APPLIED MICROBIOLOGY 2009; 67:65-108. [PMID: 19245937 DOI: 10.1016/s0065-2164(08)01003-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Medical treatments and personal hygiene lead to the steady release of pharmaceutical and personal care products (PPCPs) into the environment. Some of these PPCPs have been shown to have detrimental environmental effects and could potentially impact human health. Understanding the biological transformation of PPCPs is essential for accurately determining their ultimate environmental fate, conducting accurate risk assessments, and improving PPCP removal. We summarize the current literature concerning the biological transformation of PPCPs in wastewater treatment plants, the environment, and by pure cultures of bacterial isolates. Although some PPCPs, such as ibuprofen, are readily degraded under most studied conditions, others, such as carbamazepine, tend to be recalcitrant. This variation in the biodegradability of PPCPs can be attributed to structural differences, because PPCPs are classified by application, not chemical structure. The degradation pathways of octylphenol by Sphingomonas sp. strain PWE1, ibuprofen by Sphingomonas sp. strain Ibu-2, and DEET by Pseudomonas putida DTB are discussed in more detail.
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Affiliation(s)
- Jeanne Kagle
- Department of Biology, Mansfield University, Mansfield, Pennsylvania, USA
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Abstract
The insect repellent DEET is effective against a variety of medically important pests, but its mode of action still draws considerable debate. The widely accepted hypothesis that DEET interferes with the detection of lactic acid has been challenged by demonstrated DEET-induced repellency in the absence of lactic acid. The most recent hypothesis suggests that DEET masks or jams the olfactory system by attenuating electrophysiological responses to 1-octen-3-ol. Our research shows that mosquitoes smell DEET directly and avoid it. We performed single-unit recordings from all functional ORNs on the antenna and maxillary palps of Culex quinquefasciatus and found an ORN in a short trichoid sensillum responding to DEET in a dose-dependent manner. The same ORN responded with higher sensitivity to terpenoid compounds. SPME and GC analysis showed that odorants were trapped in conventional stimulus cartridges upon addition of a DEET-impregnated filter paper strip thus leading to the observed reduced electrophysiological responses, as reported elsewhere. With a new stimulus delivery method releasing equal amounts of 1-octen-3-ol alone or in combination with DEET we found no difference in neuronal responses. When applied to human skin, DEET altered the chemical profile of emanations by a "fixative" effect that may also contribute to repellency. However, the main mode of action is the direct detection of DEET as indicated by the evidence that mosquitoes are endowed with DEET-detecting ORNs and corroborated by behavioral bioassays. In a sugar-feeding assay, both female and male mosquitoes avoided DEET. In addition, mosquitoes responding only to physical stimuli avoided DEET.
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The molecular and cellular basis of olfactory-driven behavior in Anopheles gambiae larvae. Proc Natl Acad Sci U S A 2008; 105:6433-8. [PMID: 18427108 DOI: 10.1073/pnas.0801007105] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mosquito Anopheles gambiae is the principal Afrotropical vector for human malaria. A central component of its vectorial capacity is the ability to maintain sufficient populations of adults. During both adult and preadult (larval) stages, the mosquitoes depend on the ability to recognize and respond to chemical cues that mediate feeding and survival. In this study, we used a behavioral assay to identify a range of odorant-specific responses of An. gambiae larvae that are dependent on the integrity of the larval antennae. Parallel molecular analyses have identified a subset of the An. gambiae odorant receptors (AgOrs) that are localized to discrete neurons within the larval antennae and facilitate odor-evoked responses in Xenopus oocytes that are consistent with the larval behavioral spectrum. These studies shed light on chemosensory-driven behaviors and represent molecular and cellular characterization of olfactory processes in mosquito larvae. These advances may ultimately enhance the development of vector control strategies, targeting olfactory pathways in larval-stage mosquitoes to reduce the catastrophic effects of malaria and other diseases.
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