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Abong’o B, Agumba S, Moshi V, Simwero J, Otima J, Ochomo E. Insecticide treated eaves screens provide additional marginal protection compared to untreated eave screens under semi-field conditions in western Kenya. MALARIAWORLD JOURNAL 2024; 15:1. [PMID: 38322708 PMCID: PMC10842374 DOI: 10.5281/zenodo.10567425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Introduction Human habitats remain the main point of human-vector interaction leading to malaria transmission despite the sustained use of insecticide-treated nets and indoor residual spraying. Simple structural modifications involving screening of doors, windows and eaves have great potential for reducing indoor entry of mosquitoes. Moreover, insecticide treatment of the screen material may provide additional benefit in mosquito population reduction. Materials and Methods Four huts, each constructed inside a semi-field structure, were used in the study. Two had untreated eave and door screens and screened air cavities in place of windows (experiment 1) or were similar but with the eave screens treated with Actellic® 300CS insecticide (experiment 2). The other two huts remained unscreened throughout the study. Two hundred, 3-day old adults of F1 generation Anopheles funestus collected by aspiration or F0 reared from An. arabiensis larvae or An. arabiensis (Dongola strain) were released in each semi-field structure at dusk and recaptured the following morning. A single volunteer slept in each hut under an untreated bednet each night of the study. Recaptured mosquitoes were counted and recorded by location, either indoor or outdoor of each hut in the different semi-field structures. Results Based on modelled estimates, significantly fewer, 10% An. arabiensis from Ahero, 11% An. arabiensis Dongola strain and 10% An. funestus from Siaya were observed inside modified huts compared to unmodified ones. Treating of eave screen material with Actellic® 300CS significantly reduced indoor numbers of An. arabiensis from Ahero, to nearly 0%, and An. arabiensis Dongola strain, to 3%, compared to huts with untreated eave screens, while eliminating An. funestus indoors. These modifications cost US$180 /structure and have been observed to last more than 15 years in a different location. Conclusions Eave, door and window screening are effective ways of reducing mosquito entry into houses. Additionally, treatment of eave screen material with an effective insecticide further reduces the Anopheles population in and around the screened huts under semi-field conditions and could greatly complement existing vector control efforts.
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Affiliation(s)
- Bernard Abong’o
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
- Research World Limited, Kisumu, Kenya
| | - Silas Agumba
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Vincent Moshi
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Jacob Simwero
- Habitat for Humanity International, Lenana Road, Nairobi
| | - Jane Otima
- Habitat for Humanity International, Lenana Road, Nairobi
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
- Research World Limited, Kisumu, Kenya
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Ngoenklan R, Thanh Duong T, Duc Chinh V, Quang Thieu N, Hii J, Bangs MJ, Aum-Aung B, Suwonkerd W, Chareonviriyaphap T. Comparison of Vector Trapping Methods for Outdoor Biting Malaria Vector Surveillance in Thailand and Vietnam. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:2139-2149. [PMID: 36208216 DOI: 10.1093/jme/tjac147] [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: 06/27/2022] [Indexed: 06/16/2023]
Abstract
The performances of the human-baited double net trap (HDNT) and the human-baited host decoy trap (HDT) methods were compared against the outdoor human landing catch (OHLC) method in Thailand and Vietnam. Two study sites were selected in each country: a rural village and a nearby forest setting. The three outdoor trap methods were rotated nightly between three set trapping positions, in a pre-assigned Latin square design. Volunteers were rotated following the trap rotation to avoid bias. The greatest number of adult mosquitoes was collected from the forest sites in both countries, showing Anopheles minimus (s.s.) Theobald (96.54%) and Anopheles dirus (s.s.) Peyton & Harrison (25.71%) as the primary malaria vectors in Thailand and Vietnam, respectively. At the Thai forest site, OHLC collected significantly more anopheline mosquitoes per trap night than HDNT and HDT, with mean ± standard error values of 14.17 ± 4.42, 4.83 ± 1.56, and 4.44 ± 1.45, respectively, whilst HDNT and HDT were significantly less productive at 0.34 times and 0.31 times, respectively, than OHLC in capturing anopheline mosquitoes. However, there were no significant differences among the three methods of trapping malaria vectors for the village site. At the Vietnamese forest site, HDNT achieved the highest performance in collecting Anopheline mosquitoes at 1.54 times compared to OHLC, but there was no significant difference between the two traps. The results suggested HDNT could be a possible alternative trap to OHLC in this area. Although HDT was less efficient at attracting Anopheline mosquitoes, it was highly efficient at trapping culicine mosquitoes.
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Affiliation(s)
- Ratchadawan Ngoenklan
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Tran Thanh Duong
- Department of Entomology, National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | - Vu Duc Chinh
- Department of Entomology, National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | - Nguyen Quang Thieu
- Department of Entomology, National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | - Jeffrey Hii
- Malaria Consortium Asia, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | - Michael J Bangs
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
- Public Health and Malaria Control Department, PT Freeport Indonesia, International SOS, Papua, Indonesia
| | - Boonserm Aum-Aung
- Division of Vector Borne Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand
| | - Wannapa Suwonkerd
- Division of Vector Borne Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand
| | - Theeraphap Chareonviriyaphap
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
- Royal Society of Thailand, Bangkok, Thailand
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Hutcheson RP, Ebrahimi B, Njiru BN, Foster WA, Jany W. Attraction of the Mosquitoes Aedes aegypti and Aedes albopictus (Diptera: Culicidae) to a 3-Part Phytochemical Blend in a Mesocosm. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:440-445. [PMID: 34919131 PMCID: PMC8924971 DOI: 10.1093/jme/tjab195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Indexed: 06/14/2023]
Abstract
Aedes aegypti (L.) and Aedes albopictus (Skuse) mosquitoes of both sexes were attracted to a 3-part volatile synthetic phytochemical blend but differed according to their component ratios, 7:3:2 or 1:1:1, and their initial concentrations. These arbovirus vectors were presented with the blends as baits in paired baited and blank CFG traps in a large greenhouse mesocosm. Ae. aegypti attraction was highest at a 7:3:2 blend ratio, but at a concentration half that found most effective for an anopheline mosquito species in outdoor screenhouses. Both lower and higher concentrations yielded substantially lower attraction scores for Ae. aegypti. By contrast, the few tests conducted on Ae. albopictus showed that it was not as sensitive to concentration, but again it was more responsive to the 7:3:2 ratio of components than to the 1:1:1 ratio. The two sexes of both species were represented equally in the trap catches, indicating the potential value of this and similar attractive blends for population surveillance and control of Aedes mosquitoes.
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Affiliation(s)
- Robert P Hutcheson
- Department of Entomology and Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, OH, 43210, USA
| | - Babak Ebrahimi
- Department of Entomology and Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, OH, 43210, USA
| | - Basilio N Njiru
- Thomas Odhiambo Campus, International Centre of Insect Physiology and Ecology, Mbita Point, Nyanza, Kenya
| | - Woodbridge A Foster
- Department of Entomology and Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, OH, 43210, USA
| | - William Jany
- Clarke International LLC, St. Charles, IL, 60174, USA
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Coetzee BWT, Gaston KJ, Koekemoer LL, Kruger T, Riddin MA, Smit IPJ. Artificial Light as a Modulator of Mosquito-Borne Disease Risk. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.768090] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Light is a fundamental cue regulating a host of biological responses. The artificial modification thereof demonstrably impacts a wide range of organisms. The use of artificial light is changing in type, extent and intensity. Insect vector-borne diseases remain a global scourge, but surprisingly few studies have directly investigated the interactions between artificial light and disease vectors, such as mosquitoes. Here we briefly overview the progress to date, which highlights that artificial light must be considered as a modulator of mosquito-borne disease risk. We discuss where the mechanisms may lie, and where future research could usefully be directed, particularly in advancing understanding of the biological effects of the light environment. Further understanding of how artificial light may modulate mosquito-borne disease risk may assist in employing and redesigning light regimes that do not increase, and may even mitigate, already significant disease burdens, especially in the developing world.
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Capture of high numbers of Simulium vectors can be achieved with Host Decoy Traps to support data acquisition in the onchocerciasis elimination endgame. Acta Trop 2021; 221:106020. [PMID: 34157291 PMCID: PMC8326245 DOI: 10.1016/j.actatropica.2021.106020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 05/25/2021] [Accepted: 06/12/2021] [Indexed: 11/24/2022]
Abstract
Onchocerciasis elimination is within reach in many countries but requires enhanced surveillance of the Simulium vectors of Onchocerca volvulus. Collection of sufficient numbers of adult Simulium to detect infective O. volvulus larvae is hindered by limited sampling tools for these flies. Here, we tested for the first time the Host Decoy Trap (HDT), an exposure free method previously developed for Anopheles vectors of malaria parasites, as a potential sampling tool for adult Simulium. In three replicates of a randomized Latin square experimental design, the HDT was compared to Human Landing Catches (HLC) and the Esperanza Window Trap (EWT). A total of 8,531 adult S. damnosum sensu lato blackflies (S. squamosum group) were found in catches from the three different trapping methods. The HDT (mean catch 533 ± 111) caught significantly more S. squamosum than the EWT (mean catch 9.1 ± 2.2), a nearly 60-fold difference. There was no significant difference between the HLC (mean catch 385.6 ± 80.9) and the HDT. Larvae indistinguishable from those of O. volvulus were dissected from 2.86% of HDT samples (n = 70) and 0.35% of HLC samples (n = 285); a single infective third-stage larvae (L3) was found during dissection of a sample from the HDT. Owing to its very high capture rate, which was comparable to the HLC and significantly greater than EWT, alongside the presence of infected flies in its catch, the HDT represents a potentially valuable new tool for blackfly collection in elimination settings, where thousands of flies are needed for parasite screening.
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ACEVEDO VERONICA, AMADOR MANUEL, BARRERA ROBERTO. Improving the Safety and Acceptability of Autocidal Gravid Ovitraps (AGO Traps). JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2021; 37:61-67. [PMID: 34184049 PMCID: PMC8483263 DOI: 10.2987/21-6996.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Gravid traps that collect eggs or adult mosquitoes use color, size, or volume as well as water or plant infusions as attractants. Biorational larvicides have been used to prevent these devices from producing adult mosquitoes within the traps. Results from field assays on the use of several biorational larvicides for various mosquito species have provided mixed results in terms of increased, neutral, or reduced attraction. We investigated the use of Bacillus thuringiensis var. israelensis, spinosad, and novaluron in field assays in Puerto Rico to evaluate the behavioral response of Aedes aegypti and Culex spp. to autocidal gravid ovitraps (AGO traps). The purpose of the study was to increase the safety of these traps by preventing accidental release of adult mosquitoes when traps are opened or damaged. We also investigated whether trap color (blue, green, terracotta) that may be more amenable for use by residents in their properties induced a similar attraction response to the original black trap color. We found that the use of biorational larvicides did not significantly change the behavioral attraction of these mosquito species to AGO traps. For Ae. aegypti, green traps yielded the lowest captures while black, terracotta, and blue produced similar higher yields. Culex spp. in black traps showed significantly higher captures compared with other colors. These results suggest that black, terracotta, or blue AGO traps can be used for the surveillance and control of Ae. aegypti.
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Affiliation(s)
| | | | - ROBERTO BARRERA
- Corresponding author. Roberto Barrera, Ph.D. Entomology and Ecology Team. Dengue Branch, DBVD, Centers for Disease Control and Prevention (CDC). 1324 Calle Canada, San Juan, Puerto Rico 00920. Ph: 787-706-2467. Fax: 787-706-2496.
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