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Silalahi CN, Yasin A, Chen ME, Ahmad I, Neoh KB. Behavioral responses and life history traits of Taiwanese and Indonesian populations of Aedes aegypti surviving deltamethrin-clothianidin treatment. Parasit Vectors 2024; 17:117. [PMID: 38454517 PMCID: PMC10921677 DOI: 10.1186/s13071-024-06189-6] [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: 09/17/2023] [Accepted: 02/08/2024] [Indexed: 03/09/2024] Open
Abstract
BACKGROUND Indoor residual spraying (IRS) capitalizes on the natural behavior of mosquitoes because Aedes aegypti commonly seeks indoor resting sites after a blood meal. This behavior allows mosquitoes to be exposed to insecticide-treated surfaces and subsequently killed. Combinations of deltamethrin and clothianidin with different modes of action have shown promise in IRS, effectively targeting both susceptible and pyrethroid-resistant malaria vectors. However, the effects of this approach on Aedes mosquitoes remain unclear. The present study tested the effects of deltamethrin-clothianidin mixture treatment on behavioral responses and life history traits of Taiwanese and Indonesian populations of Ae. aegypti. METHODS We adopted an excito-repellent approach to explore the behavioral responses of pyrethroid-resistant Ae. aegypti populations from Indonesia and Taiwan to a deltamethrin-clothianidin mixture used in contact irritancy and non-contact repellency treatments. We further evaluated the life history traits of surviving mosquitoes (i.e., delayed mortality after 7-day post-treatment, longevity, fecundity, and egg hatching) and investigated the potential transgenerational hormetic effects of insecticide exposure (i.e., development rate and survival of immatures and adult mosquitos). RESULTS All tested field populations of Ae. aegypti displayed strong contact irritancy responses; the percentage of escape upon insecticide exposure ranged from 38.8% to 84.7%. However, repellent effects were limited, with the escape percentage ranging from 4.3% to 48.9%. We did not observe immediate knockdown or mortality after 24 h, and less than 15% of the mosquitoes exhibited delayed mortality after a 7-day exposure period. However, the carryover effects of insecticide exposure on the survival of immature mosquitoes resulted in approximately 25% higher immature mortality than that in the control. By contrast, we further documented stimulated survivor reproduction and accelerated transgenerational immature development resulting from the sublethal effects of the insecticide mixture. In particular, the number of eggs laid by treated (both treatments) female mosquitoes increased by at least 60% compared with that of eggs laid by control female mosquitoes. CONCLUSIONS IRS with deltamethrin-clothianidin effectively deters Aedes mosquitoes from entering residential areas and thereby reduces mosquito bites. However, the application rate (deltamethrin: 25 mg/m2; clothianidin: 200 mg/m2) may be insufficient to effectively kill Aedes mosquitoes. Insecticide response appears to vary across mosquito species; their behavioral and physiological responses to sublethal doses have crucial implications for mosquito control programs.
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Affiliation(s)
| | - Aqsa Yasin
- Department of Entomology, National Chung Hsing University, 145 Xingda Rd., 402, Taichung, Taiwan
| | - Mei-Er Chen
- Department of Entomology, National Chung Hsing University, 145 Xingda Rd., 402, Taichung, Taiwan
| | - Intan Ahmad
- School of Life Sciences and Technology, Institut Teknologi Bandung, Bandung, West Java, 40132, Indonesia
| | - Kok-Boon Neoh
- Department of Entomology, National Chung Hsing University, 145 Xingda Rd., 402, Taichung, Taiwan.
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Wei L, FernÁndez-Santos NA, Hamer GL, Lara-RamÍrez EE, RodrÍguez-PÉrez MA. Daytime Resting Activity of Aedes Aegypti and Culex Quinquefasciatus Populations in Northern Mexico. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2023; 39:157-167. [PMID: 37603406 DOI: 10.2987/23-7122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Abstract
Aedes aegypti and Culex quinquefasciatus are disease vectors distributed throughout much of the world and are responsible for a high burden of vector-borne disease, which has increased during the last 2 decades. Most pathogens vectored by these mosquitoes do not have therapeutic remedies; thus, combating these diseases is dependent upon vector control. Improvements in vector control strategies are urgently needed, but these hinge on understanding the biology and ecology of Ae. aegypti and Cx. quinquefasciatus. Both species have been extensively investigated, but further knowledge on diel resting activity of these vectors can improve vector surveillance and control tools for targeting resting vector populations. From April to December 2021, we determined outdoor daytime resting habits of Ae. aegypti and Cx. quinquefasciatus male, female, and blood-fed female populations in Reynosa, Mexico, using large red odor-baited wooden box traps. The daytime resting activity for Ae. aegypti males, females, and blood-fed females was restricted to a period between 0900 h and 1300 h, with a peak at 0900 h, while the resting activity of Cx. quinquefasciatus male, female, and blood-fed females was between 0700 h and 1100 h, with a peak at 0700 h. A generalized additive model was developed to relate relative humidity and temperature to resting Cx. quinquefasciatus and Ae. aegypti male, female, and blood-fed populations caught in traps. This study advances the understanding of outdoor resting behavior for 2 important vector mosquito species and discusses future studies to fill additional knowledge gaps.
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Facchinelli L, Alsharif B, Jones JD, Matope A, Barbosa RMR, Ayres CFJ, McCall PJ. Mapping Aedes aegypti indoor resting behavior reveals a preference vulnerable to householder-led vector control. PNAS NEXUS 2023; 2:pgad226. [PMID: 37497049 PMCID: PMC10368326 DOI: 10.1093/pnasnexus/pgad226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 05/04/2023] [Accepted: 06/28/2023] [Indexed: 07/28/2023]
Abstract
Many mosquito vectors rest inside human habitations, a behavioral trait that is exploited for vector control by indoor residual spraying (IRS) of interior walls with insecticide. Although IRS and its refined version targeted IRS are very effective against Aedes aegypti, they are expensive and logistically challenging to deliver in densely populated urban areas where outbreaks of dengue and other arboviruses are the greatest challenge. In experiments in Recife, Brazil, we set out to quantify the indoor resting behavior of Ae. aegypti at a level beyond that previously reported. We found that significantly more Ae. aegypti males, unfed and fed females visited the base of walls (height 0-20 cm, corresponding to 12.3% of the total wall surface) more frequently than upper wall areas, with the difference more pronounced at higher temperatures. When the lowest 20 cm of the walls was treated with an appropriate insecticide and colored black, we recorded up to 85% cumulative mortality after 24-h exposure in the experimental room. The findings are significant because feasibly, householders could treat this small and accessible target zone manually, without the need for visits by costly IRS teams or equipment, reducing insecticide use and enabling communities to actively protect their own indoor environment.
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Affiliation(s)
| | - Bashir Alsharif
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fiocruz Pernambuco, 50.740-465 Recife (PE), Brazil
| | - Jeff D Jones
- Vector Biology Department, Liverpool School of Tropical Medicine, L15QA, Liverpool, UK
| | - Agnes Matope
- Vector Biology Department, Liverpool School of Tropical Medicine, L15QA, Liverpool, UK
| | - Rôsangela M R Barbosa
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fiocruz Pernambuco, 50.740-465 Recife (PE), Brazil
| | - Constância F J Ayres
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fiocruz Pernambuco, 50.740-465 Recife (PE), Brazil
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4
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Seang-Arwut C, Hanboonsong Y, Muenworn V, Rocklöv J, Haque U, Ekalaksananan T, Paul RE, Overgaard HJ. Indoor resting behavior of Aedes aegypti (Diptera: Culicidae) in northeastern Thailand. Parasit Vectors 2023; 16:127. [PMID: 37060087 PMCID: PMC10103527 DOI: 10.1186/s13071-023-05746-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/17/2023] [Indexed: 04/16/2023] Open
Abstract
BACKGROUND Aedes aegypti is a vector of several arboviruses, notably dengue virus (DENV), which causes dengue fever and is often found resting indoors. Culex spp. are largely nuisance mosquitoes but can include species that are vectors of zoonotic pathogens. Vector control is currently the main method to control dengue outbreaks. Indoor residual spraying can be part of an effective vector control strategy but requires an understanding of the resting behavior. Here we focus on the indoor-resting behavior of Ae. aegypti and Culex spp. in northeastern Thailand. METHODS Mosquitoes were collected in 240 houses in rural and urban settings from May to August 2019 at two collection times (morning/afternoon), in four room types (bedroom, bathroom, living room and kitchen) in each house and at three wall heights (< 0.75 m, 0.75-1.5 m, > 1.5 m) using a battery-driven aspirator and sticky traps. Household characteristics were ascertained. Mosquitoes were identified as Ae. aegypti, Aedes albopictus and Culex spp. Dengue virus was detected in Ae. aegypti. Association analyses between urban/rural and within-house location (wall height, room), household variables, geckos and mosquito abundance were performed. RESULTS A total of 2874 mosquitoes were collected using aspirators and 1830 using sticky traps. Aedes aegypti and Culex spp. accounted for 44.78% and 53.17% of the specimens, respectively. Only 2.05% were Ae. albopictus. Aedes aegypti and Culex spp. rested most abundantly at intermediate and low heights in bedrooms or bathrooms (96.6% and 85.2% for each taxon of the total, respectively). Clothes hanging at intermediate heights were associated with higher mean numbers of Ae. aegypti in rural settings (0.81 [SEM: 0.08] vs. low: 0.61 [0.08] and high: 0.32 [0.09]). Use of larval control was associated with lower numbers of Ae. aegypti (yes: 0.61 [0.08]; no: 0.70 [0.07]). All DENV-positive Ae. aegypti (1.7%, 5 of 422) were collected in the rural areas and included specimens with single, double and even triple serotype infections. CONCLUSIONS Knowledge of the indoor resting behavior of adult mosquitoes and associated environmental factors can guide the choice of the most appropriate and effective vector control method. Our work suggests that vector control using targeted indoor residual spraying and/or potentially spatial repellents focusing on walls at heights lower than 1.5 m in bedrooms and bathrooms could be part of an integrated effective strategy for dengue vector control.
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Affiliation(s)
- Chadapond Seang-Arwut
- Department of Entomology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
| | - Yupa Hanboonsong
- Department of Entomology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
| | - Vithee Muenworn
- Department of Entomology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
| | - Joacim Rocklöv
- Heidelberg Institute of Global Health & Heidelberg Interdisciplinary Centre for Scientific Computing, Heidelberg University, Heidelberg, Germany
- Department of Public Health and Clinical Medicine, Section of Sustainable Health, Umeå University, Umea, Sweden
| | - Ubydul Haque
- Rutgers Global Health Institute, New Brunswick, NJ, USA
- Department of Biostatistics and Epidemiology, School of Public Health, Rutgers University, Piscataway, NJ, USA
| | - Tipaya Ekalaksananan
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Richard E Paul
- UMR2000, Ecology and Emergence of Arthropod-Borne Pathogens Unit, Institut Pasteur, Université Paris Cité, CNRS, 75015, Paris, France
| | - Hans J Overgaard
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway.
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Facchinelli L, Badolo A, McCall PJ. Biology and Behaviour of Aedes aegypti in the Human Environment: Opportunities for Vector Control of Arbovirus Transmission. Viruses 2023; 15:636. [PMID: 36992346 PMCID: PMC10053764 DOI: 10.3390/v15030636] [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: 01/31/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/02/2023] Open
Abstract
Aedes aegypti is a ubiquitous vector of arboviruses mostly in urbanised areas throughout the tropics and subtropics and a growing threat beyond. Control of Ae. aegypti is difficult and costly, and no vaccines are available for most of the viruses it transmits. With practical control solutions our goal, ideally suitable for delivery by householders in affected communities, we reviewed the literature on adult Ae. aegypti biology and behaviour, within and close to the human home, the arena where such interventions must impact. We found that knowledge was vague or important details were missing for multiple events or activities in the mosquito life cycle, such as the duration or location of the many periods when females rest between blood feeding and oviposition. The existing body of literature, though substantial, is not wholly reliable, and evidence for commonly held "facts" range from untraceable to extensive. Source references of some basic information are poor or date back more than 60 years, while other information that today is accepted widely as "fact" is not supported by evidence in the literature. Many topics, e.g., sugar feeding, resting preferences (location and duration), and blood feeding, merit being revisited in new geographical regions and ecological contexts to identify vulnerabilities for exploitation in control.
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Affiliation(s)
- Luca Facchinelli
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Athanase Badolo
- Laboratoire d’Entomologie Fondamentale et Appliquée, Université Joseph KI-ZERBO, Ouagadougou 03 BP 7021, Burkina Faso
| | - Philip J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
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Hellhammer F, Heidtmann H, Freise F, Becker SC. Effects of Color and Light Intensity on the Foraging and Oviposition Behavior of Culex pipiens biotype molestus Mosquitoes. INSECTS 2022; 13:993. [PMID: 36354817 PMCID: PMC9698050 DOI: 10.3390/insects13110993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/21/2022] [Accepted: 10/25/2022] [Indexed: 06/16/2023]
Abstract
Mosquitoes are the most important vector of arboviruses; thus, controlling mosquito population is a key point for controlling these diseases. Two major factors that influence mosquito population size are the availability of blood hosts and suitable oviposition sites. Behavioral mechanisms by which Culex pipiens biotype molestus mosquitoes locate their hosts or oviposition sites are influenced by physical and chemical factors. The present study evaluated the impact of the colors (for human eyes) red, green, blue and yellow in combination with different light intensities on preferences for oviposition and foraging sites under laboratory conditions. We identified the color red as the overall favored color for both target behaviors, which was only surpassed by black as the foraging stimulus. Altogether, we described two new inexpensive and simple bioassays, which can be used as a mosquito-tracking method for behavioral tests and as an oviposition trap to monitor Culex pipiens biotype molestus populations.
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Affiliation(s)
- Fanny Hellhammer
- Institute for Parasitology, Center for Infection Medicine, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Hella Heidtmann
- Institute for Parasitology, Center for Infection Medicine, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Fritjof Freise
- Department of Biometry, Epidemiology and Information Processing, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Stefanie C. Becker
- Institute for Parasitology, Center for Infection Medicine, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
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7
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Recla L, Rheault M, Golovin K. Complete Inhibition of Vertical Mosquito Landing through Topographical Surface Design. ACS APPLIED MATERIALS & INTERFACES 2022; 14:38320-38327. [PMID: 35960251 DOI: 10.1021/acsami.2c08790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Mosquito-borne diseases such as dengue, chikungunya, and malaria have long been a health and economic burden in our society. Such illnesses develop after the pathogen, here arboviruses, are transmitted to humans by female mosquitoes during blood meals. In the case of dengue and chikungunya, such pathogens are transmitted to humans by infected Aedes aegypti females. Prior to feeding the insects rest on vertical surfaces. In this work, a surface roughness threshold was observed for live Aedes aegypti colonies, and below a root-mean-squared roughness of Sq < 0.124 μm the mosquitoes were physically incapable of gripping vertical substrates. This roughness threshold was unaffected by surface wettability or relative humidity. The importance of topographical feature height was understood using a claw-hooking model considering friction. Local defects above this threshold allowed claw hooking to take place, emphasizing the importance of surface uniformity. An antimosquito coating was developed that reduced surface roughness below this threshold when it was applied to realistic surfaces such as wood, brick, wall laminates, and tile. Lowering the surface roughness below the threshold reduced the number of mosquitoes capable of landing on the surfaces by 100%: i.e., no mosquitoes were able to adhere to the treated surfaces. The ability to completely inhibit Aedes aegypti females from landing on surfaces represents a new vector-borne disease control strategy that does not suffer from the nontarget toxicity, resistance, or ecosystem disruption associated with conventional chemical control strategies.
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Affiliation(s)
- Letícia Recla
- School of Engineering, The University of British Columbia, Kelowna, British Columbia V1V 1V7, Canada
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
| | - Mark Rheault
- Department of Biology, The University of British Columbia, Kelowna, British Columbia V1V 1V7, Canada
| | - Kevin Golovin
- School of Engineering, The University of British Columbia, Kelowna, British Columbia V1V 1V7, Canada
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
- Department of Materials Science & Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
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Sirisopa P, Sukkanon C, Bangs MJ, Nakasathien S, Hii J, Grieco JP, Achee NL, Manguin S, Chareonviriyaphap T. Scientific achievements and reflections after 20 years of vector biology and control research at the Pu Teuy mosquito field research station, Thailand. Malar J 2022; 21:44. [PMID: 35164748 PMCID: PMC8842738 DOI: 10.1186/s12936-022-04061-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 01/23/2022] [Indexed: 01/25/2023] Open
Abstract
Additional vector control tools are needed to supplement current strategies to achieve malaria elimination and control of Aedes-borne diseases in many settings in Thailand and the Greater Mekong Sub-region. Within the next decade, the vector control community, Kasetsart University (KU), and the Ministry of Higher Education, Science, Research and Innovation must take full advantage of these tools that combine different active ingredients with different modes of action. Pu Teuy Mosquito Field Research Station (MFRS), Department of Entomology, Faculty of Agriculture, Kasetsart University (KU), Thailand was established in 2001 and has grown into a leading facility for performing high-quality vector biology and control studies and evaluation of public health insecticides that are operationally relevant. Several onsite mosquito research platforms have been established including experimental huts, a 40-m long semi-field screening enclosure, mosquito insectary, field-laboratory, and living quarters for students and researchers. Field research and assessments ranged from 'basic' investigations on mosquito biology, taxonomy and genetics to more 'applied' studies on responses of mosquitoes to insecticides including repellency, behavioural avoidance and toxicity. In the course of two decades, 51 peer-reviewed articles have been published, and 7 masters and 16 doctoral degrees in Entomology have been awarded to national and international students. Continued support of key national stakeholders will sustain MFRS as a Greater Mekong Subregion centre of excellence and a resource for both insecticide trials and entomological research.
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Affiliation(s)
- Patcharawan Sirisopa
- grid.9723.f0000 0001 0944 049XDepartment of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
| | - Chutipong Sukkanon
- grid.412867.e0000 0001 0043 6347Department of Medical Technology, School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat, 80160 Thailand
| | - Michael J. Bangs
- grid.9723.f0000 0001 0944 049XDepartment of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
| | - Sutkhet Nakasathien
- grid.9723.f0000 0001 0944 049XDepartment of Agronomy, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
| | - Jeffrey Hii
- grid.1011.10000 0004 0474 1797College of Public Health, Medical and Veterinary Sciences, James Cook University, North Queensland, QLD 4810 Australia
| | - John P. Grieco
- grid.131063.60000 0001 2168 0066Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN USA
| | - Nicole L. Achee
- grid.131063.60000 0001 2168 0066Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN USA
| | - Sylvie Manguin
- grid.463853.f0000 0004 0384 4663HSM, Univ. Montpellier, CNRS, IRD, IMT, Montpellier, France
| | - Theeraphap Chareonviriyaphap
- grid.9723.f0000 0001 0944 049XDepartment of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
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Tainchum K, Bangs MJ, Sathantriphop S, Chareonviriyaphap T. Effect of Different Wall Surface Coverage With Deltamethrin-Treated Netting on the Reduction of Indoor-Biting Anopheles Mosquitoes (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:2299-2307. [PMID: 34114017 DOI: 10.1093/jme/tjab095] [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: 11/24/2020] [Indexed: 06/12/2023]
Abstract
Indoor residual spray with deltamethrin remains the most common tool for reducing malaria transmission in Thailand. Deltamethrin is commonly used to spray the entire inner surfaces of the walls to prevent mosquitoes from resting. This study compared the mosquito landing responses on humans inside three experimental huts treated with deltamethrin at three different extents of wall coverage (25%, 50%, and full coverage), with one clean/untreated hut serving as a control. There were no significant differences between the numbers of Anopheles mosquitoes landing in the 50% and full coverage huts, whereas, in comparison to both of these, there was a significantly greater number landing in the 25% coverage hut. This study demonstrates that varying the percent coverage of indoor surfaces with deltamethrin-treated netting influences the blood-feeding success of wild Anopheles, and our findings suggest that it may be possible to reduce the extent of insecticide surface treatment while maintaining equivalent mosquito avoidance action to that seen in fully treated structures.
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Affiliation(s)
- Krajana Tainchum
- Center for Advanced Studies for Agriculture and Food, KU Institute for Advanced Studies, Kasetsart University, Bangkok, Thailand
- Agricultural Innovation and Management Division, Faculty of Natural Resources, Prince of Songkla University, Songkhla, Thailand
| | - Michael J Bangs
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
- Public Health & Malaria Control Department, PT. Freeport Indonesia, International SOS, Kuala Kencana, Papua, Indonesia
| | - Sunaiyana Sathantriphop
- National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Theeraphap Chareonviriyaphap
- Center for Advanced Studies for Agriculture and Food, KU Institute for Advanced Studies, Kasetsart University, Bangkok, Thailand
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
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Berté D, De Meeûs T, Kaba D, Séré M, Djohan V, Courtin F, N'Djetchi Kassi M, Koffi M, Jamonneau V, Ta BTD, Solano P, N'Goran EK, Ravel S. Population genetics of Glossina palpalis palpalis in sleeping sickness foci of Côte d'Ivoire before and after vector control. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2019; 75:103963. [PMID: 31301424 PMCID: PMC6853165 DOI: 10.1016/j.meegid.2019.103963] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/08/2019] [Accepted: 07/09/2019] [Indexed: 10/26/2022]
Abstract
Glossina palpalis palpalis remains the major vector of sleeping sickness in Côte d'Ivoire. The disease is still active at low endemic levels in Bonon and Sinfra foci in the western-central part of the country. In this study, we investigated the impact of a control campaign on G. p. palpalis population structure in Bonon and Sinfra foci in order to adapt control strategies. Genetic variation at microsatellite loci was used to examine the population structure of different G. p. palpalis cohorts before and after control campaigns. Isolation by distance was observed in our sampling sites. Before control, effective population size was high (239 individuals) with dispersal at rather short distance (731 m per generation). We found some evidence that some of the flies captured after treatment come from surrounding sites, which increased the genetic variance. One Locus, GPCAG, displayed a 1000% increase of subdivision measure after control while other loci only exhibited a substantial increase in variance of subdivision. Our data suggested a possible trap avoidance behaviour in G. p. palpalis. It is important to take into account and better understand the possible reinvasion from neighboring sites and trap avoidance for the sake of sustainability of control campaigns effects.
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Affiliation(s)
- Djakaridja Berté
- Institut Pierre Richet/Institut National de Santé Publique, Bouaké, Côte d'Ivoire; Université Felix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | | | - Dramane Kaba
- Institut Pierre Richet/Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Modou Séré
- Université de Dédougou (UDDG), Dédougou, Burkina Faso
| | - Vincent Djohan
- Institut Pierre Richet/Institut National de Santé Publique, Bouaké, Côte d'Ivoire; Université Felix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | - Fabrice Courtin
- Intertryp, IRD, Cirad, Univ Montpellier, Montpellier, France
| | - Martial N'Djetchi Kassi
- Laboratoire des Interactions Hôte-Microorganisme-Environnement et Evolution, Unité de Formation et de Recherche Environnement, Université Jean Lorougnon Guédé, Daloa, Côte d'Ivoire
| | - Mathurin Koffi
- Laboratoire des Interactions Hôte-Microorganisme-Environnement et Evolution, Unité de Formation et de Recherche Environnement, Université Jean Lorougnon Guédé, Daloa, Côte d'Ivoire
| | | | - Bi Tra Dieudonné Ta
- Institut Pierre Richet/Institut National de Santé Publique, Bouaké, Côte d'Ivoire; Université Felix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | - Philippe Solano
- Intertryp, IRD, Cirad, Univ Montpellier, Montpellier, France
| | | | - Sophie Ravel
- Intertryp, IRD, Cirad, Univ Montpellier, Montpellier, France
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Dunbar MW, Correa-Morales F, Dzul-Manzanilla F, Medina-Barreiro A, Bibiano-Marín W, Morales-Ríos E, Vadillo-Sánchez J, López-Monroy B, Ritchie SA, Lenhart A, Manrique-Saide P, Vazquez-Prokopec GM. Efficacy of novel indoor residual spraying methods targeting pyrethroid-resistant Aedes aegypti within experimental houses. PLoS Negl Trop Dis 2019; 13:e0007203. [PMID: 30817759 PMCID: PMC6394901 DOI: 10.1371/journal.pntd.0007203] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 01/30/2019] [Indexed: 12/17/2022] Open
Abstract
Challenges in maintaining high effectiveness of classic vector control in urban areas has renewed the interest in indoor residual spraying (IRS) as a promising approach for Aedes-borne disease prevention. While IRS has many benefits, application time and intrusive indoor applications make its scalability in urban areas difficult. Modifying IRS to account for Ae. aegypti resting behavior, named targeted IRS (TIRS, spraying walls below 1.5 m and under furniture) can reduce application time; however, an untested assumption is that modifications to IRS will not negatively impact entomological efficacy. We conducted a comparative experimental study evaluating the residual efficacy of classically-applied IRS (as developed for malaria control) compared to two TIRS application methods using a carbamate insecticide against a pyrethroid-resistant, field-derived Ae. aegypti strain. We performed our study within a novel experimental house setting (n = 9 houses) located in Merida (Mexico), with similar layouts and standardized contents. Classic IRS application (insecticide applied to full walls and under furniture) was compared to: a) TIRS: insecticide applied to walls below 1.5 m and under furniture, and b) Resting Site TIRS (RS-TIRS): insecticide applied only under furniture. Mosquito mortality was measured eight times post-application (out to six months post-application) by releasing 100 Ae. aegypti females /house and collecting live and dead individuals after 24 hrs exposure. Compared to Classic IRS, TIRS and RS-TIRS took less time to apply (31% and 82% reduction, respectively) and used less insecticide (38% and 85% reduction, respectively). Mortality of pyrethroid-resistant Ae. aegypti did not significantly differ among the three IRS application methods up to two months post application, and did not significantly differ between Classic IRS and TIRS up to four months post application. These data illustrate that optimizing IRS to more efficiently target Ae. aegypti can both reduce application time and insecticide volume with no apparent reduction in entomological efficacy. Vector control is the primary strategy for managing Aedes aegypti and reducing transmission of Aedes-borne diseases; however, the indoor resting behavior of Ae. aegypti and the evolution of insecticide resistance reduces the effectiveness of many vector control tactics. Indoor residual spraying (IRS) is effective against Ae. aegypti, but lengthy application time makes IRS difficult to scale within urban environments. We compared the application and entomological efficacy of Classic IRS against two novel Aedes-targeting IRS application methods (Targeted IRS [TIRS]- insecticide applied to walls below 1.5 m and under furniture and Resting Site TIRS [RS-TIRS]- insecticide applied only under furniture) within experimental houses using a carbamate insecticide. Both TIRS and RS-TIRS took less time to apply and used less insecticide compared to Classic IRS. Mortality of pyrethroid-resistant Ae. aegypti did not differ among treatments out to two months post-application, and there was no difference in mortality between Classic IRS and TIRS out to four months post-application. These data provide evidence that IRS application methods can be improved to take less time and insecticide yet not lose entomological efficacy, making TIRS more scalable within urban environments. However, larger field studies with epidemiologic endpoints are needed to further assess the efficacy of these modified TIRS techniques.
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Affiliation(s)
- Mike W. Dunbar
- Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
| | - Fabian Correa-Morales
- Centro Nacional de Programas Preventivos y Control de Enfermedades (CENAPRECE) Secretaría de Salud México, Ciudad de México, México
| | - Felipe Dzul-Manzanilla
- Centro Nacional de Programas Preventivos y Control de Enfermedades (CENAPRECE) Secretaría de Salud México, Ciudad de México, México
| | - Anuar Medina-Barreiro
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, México, México
| | - Wilbert Bibiano-Marín
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, México, México
| | - Evaristo Morales-Ríos
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, México, México
| | - José Vadillo-Sánchez
- Centro Nacional de Programas Preventivos y Control de Enfermedades (CENAPRECE) Secretaría de Salud México, Ciudad de México, México
| | - Beatriz López-Monroy
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, Nuevo León, México
| | - Scott A. Ritchie
- College of Public Health, Medical & Vet Sciences, James Cook University, Cairns, Australia
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Pablo Manrique-Saide
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, México, México
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Thanispong K, Sathantriphop S, Tisgratog R, Tainchum K, Sukkanon C, Bangs MJ, Chareonviriyaphap T. Optimal Discriminating Concentrations of Six Synthetic Pyrethroids for Monitoring Insecticide Susceptibility in Anopheles minimus (Diptera: Culicidae), a Primary Malaria Vector in Thailand. JOURNAL OF ECONOMIC ENTOMOLOGY 2018; 111:2375-2382. [PMID: 29992231 DOI: 10.1093/jee/toy199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Indexed: 06/08/2023]
Abstract
Malaria is a serious mosquito-borne disease transmitted to humans by Anopheles mosquitoes. Seven species of Anopheles are important malaria vectors in Thailand and all remain susceptible to pyrethroid insecticides, despite decades of use in public health mosquito control programs. However, for a more refined and accurate approach to temporal monitoring of susceptibility patterns to commonly used pyrethroids to control adult Anopheles mosquitoes, it is preferred to have specific concentrations for more discriminating testing. A laboratory strain of Anopheles minimus Theobald was used to establish baseline concentrations for susceptibility to six different synthetic pyrethroids-deltamethrin, permethrin, bifenthrin, cypermethrin, α-cypermethrin, and λ-cyhalothrin using the World Health Organization (WHO) adult bioassay system. Final discriminating concentrations of each active ingredient were determined based on doubling LC99 for each chemical to arrive at the following percent concentrations: deltamethrin (0.009%), permethrin (0.551%), bifenthrin (0.12%), cypermethrin (0.104%), α-cypermethrin (0.034%), and λ-cyhalothrin (0.019%). For permethrin, deltamethrin, α-cypermethrin, and λ-cyhalothrin, all revised percentages were lower than currently recommended discriminating concentrations by WHO. Using the newly derived concentrations, insecticide susceptibility tests were followed in a field population of An. minimus s.l. from Kanchanaburi Province. Deltamethrin, bifenthrin, and λ-cyhalothrin produced 100% kill, whereas permethrin, cypermethrin, and α-cypermethrin gave between 92.9 and 97.7% mortality, indicating lower sensitivity (tolerance). Routine monitoring of insecticide susceptibility in An. minimus wild populations throughout Thailand should continue to ensure that insecticides in use are effective to control this vector species.
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Affiliation(s)
- Kanutcharee Thanispong
- Department of Disease Control, Bureau of Vector-Borne Diseases, Ministry of Public Health, Nonthaburi 11000, Thailand
| | - Sunaiyana Sathantriphop
- Department of Medical Sciences, National Institute of Health, Ministry of Public Health, Nonthaburi 11000, Thailand
| | - Rungarun Tisgratog
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
| | - Krajana Tainchum
- Department of Pest Management, Faculty of Natural Resources, Prince of Songkla University, Songkhla 90112, Thailand
| | - Chutipong Sukkanon
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
| | - Michael J Bangs
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
- Public Health and Malaria Control Department, PT. Freeport Indonesia, International SOS, Kuala Kencana, Papua 99920, Indonesia
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Dieng H, Satho T, Binti Arzemi NA, Aliasan NE, Abang F, Wydiamala E, Miake F, Zuharah WF, Abu Kassim NF, Morales Vargas RE, Morales NP, Noweg GT. Exposure of a diurnal mosquito vector to floral mimics: Foraging responses, feeding patterns, and significance for sugar bait technology. Acta Trop 2018; 185:230-238. [PMID: 29856985 DOI: 10.1016/j.actatropica.2018.05.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/09/2018] [Accepted: 05/26/2018] [Indexed: 11/16/2022]
Abstract
Food location by mosquitoes is mediated by resource-derived olfactory and visual signals. Smell sensation is intermittent and dependent on the environment, whereas visual signals are continual and precede olfactory cues. Success of mosquito bait technology, where olfactory cues are used for attraction, is being impeded by reduced attractiveness. Despite proof that mosquitoes respond to colored objects, including those mimicking floral shape, and that they can discriminate among flowers, the impacts of artificial flowers on foraging remain unexplored. Using artificial flowers with sugar rewards, we examined the foraging responses of Aedes aegypti to various colors in equal choice bioassays. Starved adults were exposed to single flowers with petals of a given color (Single Blue Flowers [SBFs]; Single Red Flowers [SRFs]; Single Yellow Flowers [SYFs]; Single Pink Flowers [SPIFs]; and Single Purple Flowers [SPFs]) and two others with white petals (SWFs). Discrepancies in response time, visitation, feeding, and resting of both sexes were compared between colored flowers and SWFs. Ae. aegypti exhibited shorter response times to colored flowers compared to SWFs, but this behavior was mostly seen for SBFs or SYFs in females, and SRFs, SYFs, SPIFs, or SPFs in males. When provided an option to land on colored flowers and SWFs, female visitation occurred at high rates on SBFs, SRFs, SYFs, SPIFs, and SPFs; for males, this preference for colored flowers was seen to a lesser degree on SBF and SPIFs. Both sexes exhibited preference for colored flowers as sugar sources, but with different patterns: SPIFs, SRFs, SYFs, and SPFs for females; SYFs, SPFs, SPIFs and SRFs for males. Females preferentially rested on colored flowers when in competition with SWFs, but this preference was more pronounced for SPFs, SRFs, and SBFs. Males exhibited an increased preference for SRFs, SPFs, and SYFs as resting sites. Our results indicated the attraction of Ae. aegypti to rewarding artificial flowers, in some cases in ways similar to live flowering plants. The discovery that both male and female Ae. aegypti can feed on nectar mimics held by artificial flowers opens new avenues for improving sugar bait technology and for developing new attract-and-kill devices.
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Affiliation(s)
- Hamady Dieng
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Malaysia.
| | - Tomomitsu Satho
- Faculty of Pharmaceutical Sciences, Fukuoka University, Japan
| | | | - Nur Ezzati Aliasan
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Malaysia
| | - Fatimah Abang
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, Kota Samarahan, Malaysia
| | - Erida Wydiamala
- Faculty of Medicine, Lambung Mangkurat University, South Kalimantan, Indonesia
| | - Fumio Miake
- Faculty of Pharmaceutical Sciences, Fukuoka University, Japan
| | - Wan Fatma Zuharah
- School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia
| | | | | | | | - Gabriel Tonga Noweg
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Malaysia
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Dzul-Manzanilla F, Ibarra-López J, Bibiano Marín W, Martini-Jaimes A, Leyva JT, Correa-Morales F, Huerta H, Manrique-Saide P, Vazquez-Prokopec GM. Indoor Resting Behavior of Aedes aegypti (Diptera: Culicidae) in Acapulco, Mexico. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:501-504. [PMID: 28011725 DOI: 10.1093/jme/tjw203] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/24/2016] [Indexed: 06/06/2023]
Abstract
The markedly anthropophilic and endophilic behaviors of Aedes aegypti (L.) make it a very efficient vector of dengue, chikungunya, and Zika viruses. Although a large body of research has investigated the immature habitats and conditions for adult emergence, relatively few studies have focused on the indoor resting behavior and distribution of vectors within houses. We investigated the resting behavior of Ae. aegypti indoors in 979 houses of the city of Acapulco, Mexico, by performing exhaustive indoor mosquito collections to describe the rooms and height at which mosquitoes were found resting. In total, 1,403 adult and 747 female Ae. aegypti were collected, primarily indoors (98% adults and 99% females). Primary resting locations included bedrooms (44%), living rooms (25%), and bathrooms (20%), followed by kitchens (9%). Aedes aegypti significantly rested below 1.5 m of height (82% adults, 83% females, and 87% bloodfed females); the odds of finding adult Ae. aegypti mosquitoes below 1.5 m was 17 times higher than above 1.5 m. Our findings provide relevant information for the design of insecticide-based interventions selectively targeting the adult resting population, such as indoor residual spraying.
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Affiliation(s)
- Felipe Dzul-Manzanilla
- Centro Nacional de Programas Preventivos y Control de Enfermedades (CENAPRECE), Secretaria de Salud, Eje 4 Sur Benjamín Franklin, Escandón, Ciudad de Mexico, Mexico (; ; )
| | - Jésus Ibarra-López
- Centro Nacional de Programas Preventivos y Control de Enfermedades (CENAPRECE), Secretaria de Salud, Eje 4 Sur Benjamín Franklin, Escandón, Ciudad de Mexico, Mexico (; ; )
| | - Wilbert Bibiano Marín
- Unidad Colaborativa para Bioensayos Entomológicos, Departamento de Zoología, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Carretera Mérida-Xmatkuil Km. 15.5, Merida, Yucatan, México (; )
| | - Andrés Martini-Jaimes
- Servicios Estatales de Salud de Guerrero, Guerrero, Ruffo Figueroa SN, Burocratas, 39090 Chilpancingo de los Bravo, Mexico
| | - Joel Torres Leyva
- Unidad Académica de Matemáticas, Universidad Autónoma de Guerrero, Av. Javier Méndez Aponte 1, Fraccionamiento Servidor Agrario, Guerrero, Mexico
| | - Fabián Correa-Morales
- Centro Nacional de Programas Preventivos y Control de Enfermedades (CENAPRECE), Secretaria de Salud, Eje 4 Sur Benjamín Franklin, Escandón, Ciudad de Mexico, Mexico (; ; )
| | - Herón Huerta
- Instituto de Diagnóstico y Referencia Epidemiológicos (InDRE), Secretaria de Salud, Ciudad de Mexico, Francisco de P. Miranda 177, Lomas de Plateros, Mexico
| | - Pablo Manrique-Saide
- Unidad Colaborativa para Bioensayos Entomológicos, Departamento de Zoología, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Carretera Mérida-Xmatkuil Km. 15.5, Merida, Yucatan, México (; )
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15
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Wagman JM, Grieco JP, Bautista K, Polanco J, Briceño I, King R, Achee NL. The field evaluation of a push-pull system to control malaria vectors in northern Belize, Central America. Malar J 2015; 14:184. [PMID: 25925395 PMCID: PMC4425932 DOI: 10.1186/s12936-015-0692-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/05/2015] [Indexed: 11/23/2022] Open
Abstract
Background Campaigns for the continued reduction and eventual elimination of malaria may benefit from new and innovative vector control tools. One novel approach being considered uses a push-pull strategy, whereby spatial repellents are used in combination with outdoor baited traps. The desired effect is the behavioural manipulation of mosquito populations to elicit movement of vectors away from people and into traps. Methods Here, a prototype push-pull intervention was evaluated using an experimental hut methodology to test proof-of-principle for the strategy against two natural vector populations, Anopheles albimanus and Anopheles vestitipennis, in Belize, Central America. A Latin square study design was used to compare mosquito entry into experimental huts and outdoor traps across four different experimental conditions: 1) control, with no interventions; 2) pull, utilizing only outdoor traps; 3) push, utilizing only an indoor spatial repellent; and 4) push-pull, utilizing both interventions simultaneously. Results For An. vestitipennis, the combined use of an indoor repellent and outdoor baited traps reduced average nightly mosquito hut entry by 39% (95% CI: [0.37 – 0.41]) as compared to control and simultaneously increased the nightly average densities of An. vestitipennis captured in outdoor baited traps by 48% (95% CI: [0.22 – 0.74]), compared to when no repellent was used. Against An. albimanus, the combined push-pull treatment similarly reduced hut entry, by 54% (95% CI: [0.40 – 0.68]) as compared to control; however, the presence of a repellent indoors did not affect overall outdoor trap catch densities for this species. Against both anopheline species, the combined intervention did not further reduce mosquito hut entry compared to the use of repellent alone. Conclusions The prototype intervention evaluated here clearly demonstrated that push-pull strategies have potential to reduce human-vector interactions inside homes by reducing mosquito entry, and highlighted the possibility for the strategy to simultaneously decrease human-vector interactions outside of homes by increasing baited trap collections. However, the variation in effect on different vectors demonstrates the need to characterize the underlying behavioral ecology of target mosquitoes in order to drive local optimization of the intervention. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0692-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joseph M Wagman
- Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.
| | - John P Grieco
- College of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN, 46556, USA.
| | - Kim Bautista
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Jorge Polanco
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Ireneo Briceño
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Russell King
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Nicole L Achee
- College of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN, 46556, USA.
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Determining airborne concentrations of spatial repellent chemicals in mosquito behavior assay systems. PLoS One 2013; 8:e71884. [PMID: 24015195 PMCID: PMC3756037 DOI: 10.1371/journal.pone.0071884] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Accepted: 07/08/2013] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR). Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI) in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions. METHODOLOGY/PRINCIPAL FINDINGS A thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS) method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT) in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3) (n = 17; SD = 0.45) and 1.42 µg/m(3) (n = 30; SD = 0.96). CONCLUSIONS/SIGNIFICANCE The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h) SR concentrations in small volume (<100 L) samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds.
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