scholarly journals Comparing sterile male releases and other methods for integrated control of the tiger mosquito in temperate and tropical climates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Léa Douchet ◽  
Marion Haramboure ◽  
Thierry Baldet ◽  
Gregory L’Ambert ◽  
David Damiens ◽  
...  
Keyword(s):  
Vector Control ◽  
Mosquito Species ◽  
Integrated Control ◽  
Mass Trapping ◽  
Southwest Indian Ocean ◽  
Breeding Sites ◽  
Key Factor ◽  
Trapping Methods ◽  
Combination Of Methods ◽  
Tropical Climates

AbstractThe expansion of mosquito species worldwide is creating a powerful network for the spread of arboviruses. In addition to the destruction of breeding sites (prevention) and mass trapping, methods based on the sterile insect technique (SIT), the autodissemination of pyriproxyfen (ADT), and a fusion of elements from both of these known as boosted SIT (BSIT), are being developed to meet the urgent need for effective vector control. However, the comparative potential of these methods has yet to be explored in different environments. This is needed to propose and integrate informed guidelines into sustainable mosquito management plans. We extended a weather-dependent model of Aedes albopictus population dynamics to assess the effectiveness of these different vector control methods, alone or in combination, in a tropical (Reunion island, southwest Indian Ocean) and a temperate (Montpellier area, southern France) climate. Our results confirm the potential efficiency of SIT in temperate climates when performed early in the year (mid-March for northern hemisphere). In such a climate, the timing of the vector control action was the key factor in its success. In tropical climates, the potential of the combination of methods becomes more relevant. BSIT and the combination of ADT with SIT were twice as effective compared to the use of SIT alone.

scholarly journals Development of a chimeric odour blend for attracting gravid malaria vectors

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Betelehem Wondwosen ◽  
Mengistu Dawit ◽  
Yared Debebe ◽  
Habte Tekie ◽  
Sharon R. Hill ◽  
...  
Keyword(s):  
Vector Control ◽  
Binary Logistic Regression ◽  
Ground Level ◽  
Malaria Vectors ◽  
Volatile Components ◽  
Innovative Strategy ◽  
Breeding Sites ◽  
Logistic Regression Models ◽  
Plant Feeding ◽  
Global Vector

Abstract Background Odour-based tools targeting gravid malaria vectors may complement existing intervention strategies. Anopheles arabiensis are attracted to, and stimulated to oviposit by, natural and synthetic odours of wild and domesticated grasses associated with mosquito breeding sites. While such synthetic odour lures may be used for vector control, these may have limited efficacy when placed in direct competition with the natural source. In this study, workflows developed for plant-feeding pests was used to design and evaluate a chimeric odour blend based on shared attractive compounds found in domesticated grass odours. Methods Variants of a synthetic odour blend, composed of shared bioactive compounds previously identified in domesticated grasses, was evaluated sequentially in a two-choice olfactometer to identify a ratio-optimized attractive blend for malaria vectors. During this process, blends with ratios that were significantly more attractive than the previously identified synthetic rice blend were compared to determine which was most attractive in the two-choice olfactometer. To determine whether all volatile components of the most attractive blend were necessary for maximal attraction, subtractive assays were then conducted, in which individual components were removed for the most attractive blend, to define the final composition of the chimeric blend. Binary logistic regression models were used to determine significance in all two-choice assays. The chimeric blend was then assessed under field conditions in malaria endemic villages in Ethiopia, to assess the effect of dose, trap type, and placement relative to ground level. Field data were analyzed both descriptively and using a Welch-corrected t-test. Results A ratio-optimized chimeric blend was identified that significantly attracted gravid An. arabiensis under laboratory conditions. In the field, trap captures of An. arabiensis and Anopheles pharoensis were dependent on the presence of the lure, trap type (CDC, BG Sentinel and Suna traps), placement relevant to ground level, with low release rates generally luring more mosquitoes. Conclusions The workflow designed for the development of chimeric lures provides an innovative strategy to target odour-mediated behaviours. The chimeric lure identified here can be used in existing trapping systems, and be customized to increase sustainability, in line with goals of the Global Vector Control Response Group.

scholarly journals Impact of seasonality and malaria control interventions on Anopheles density and species composition from three areas of Uganda with differing malaria endemicity

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Henry Ddumba Mawejje ◽  
Maxwell Kilama ◽  
Simon P. Kigozi ◽  
Alex K. Musiime ◽  
Moses Kamya ◽  
...  
Keyword(s):  
Species Composition ◽  
Vector Control ◽  
Malaria Control ◽  
Mosquito Species ◽  
Density Ratio ◽  
Indoor Residual Spraying ◽  
Sub Saharan Africa ◽  
Malaria Vector Control ◽  
Vector Density ◽  
Llin Distribution

Abstract Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the malaria control interventions primarily responsible for reductions in transmission intensity across sub-Saharan Africa. These interventions, however, may have differential impact on Anopheles species composition and density. This study examined the changing pattern of Anopheles species in three areas of Uganda with markedly different transmission intensities and different levels of vector control. Methods From October 2011 to June 2016 mosquitoes were collected monthly using CDC light traps from 100 randomly selected households in three areas: Walukuba (low transmission), Kihihi (moderate transmission) and Nagongera (high transmission). LLINs were distributed in November 2013 in Walukuba and Nagongera and in June 2014 in Kihihi. IRS was implemented only in Nagongera, with three rounds of bendiocarb delivered between December 2014 and June 2015. Mosquito species were identified morphologically and by PCR (Polymerase Chain Reaction). Results In Walukuba, LLIN distribution was associated with a decline in Anopheles funestus vector density (0.07 vs 0.02 mosquitoes per house per night, density ratio [DR] 0.34, 95% CI: 0.18–0.65, p = 0.001), but not Anopheles gambiae sensu stricto (s.s.) nor Anopheles arabiensis. In Kihihi, over 98% of mosquitoes were An. gambiae s.s. and LLIN distribution was associated with a decline in An. gambiae s.s. vector density (4.00 vs 2.46, DR 0.68, 95% CI: 0.49–0.94, p = 0.02). In Nagongera, the combination of LLINs and multiple rounds of IRS was associated with almost complete elimination of An. gambiae s.s. (28.0 vs 0.17, DR 0.004, 95% CI: 0.002–0.009, p < 0.001), and An. funestus sensu lato (s.l.) (3.90 vs 0.006, DR 0.001, 95% CI: 0.0005–0.004, p < 0.001), with a less pronounced decline in An. arabiensis (9.18 vs 2.00, DR 0.15 95% CI: 0.07–0.33, p < 0.001). Conclusions LLIN distribution was associated with reductions in An. funestus s.l. in the lowest transmission site and An. gambiae s.s. in the moderate transmission site. In the highest transmission site, a combination of LLINs and multiple rounds of IRS was associated with the near collapse of An. gambiae s.s. and An. funestus s.l. Following IRS, An. arabiensis, a behaviourally resilient vector, became the predominant species, which may have implications for malaria vector control activities. Development of interventions targeted at outdoor biting remains a priority.

scholarly journals Household-Level Risk Factors for Aedes aegypti Pupal Density in Guayaquil, Ecuador

2020 ◽  
Author(s):  
Thien-An Ha ◽  
Tomás M. León ◽  
Karina Lalangui ◽  
Patricio Ponce ◽  
John M. Marshall ◽  
...  
Keyword(s):  
Risk Factors ◽  
Aedes Aegypti ◽  
Vector Control ◽  
Negative Binomial Regression Model ◽  
Control Methods ◽  
Municipal Services ◽  
Breeding Sites ◽  
Household Level ◽  
Level Model ◽  
The Impact

AbstractBackgroundVector-borne diseases are a major cause of disease burden in Guayaquil, Ecuador, especially arboviruses spread by Aedes aegypti mosquitoes. Understanding which household characteristics and risk factors lead to higher Ae. aegypti densities and consequent disease risk can help inform and optimize vector control programs.MethodsCross-sectional entomological surveys were conducted in Guayaquil between 2013 and 2016, covering household demographics, municipal services, potential breeding containers, presence of Ae. aegypti larvae and pupae, and history of using mosquito control methods. A zero-truncated negative binomial regression model was fitted to data for estimating the household pupal index. An additional model assessed the factors of the most productive breeding sites across all of the households.ResultsOf surveyed households, 610 satisfied inclusion criteria. The final household-level model found that collection of large solid items (e.g., furniture and tires) and rainfall the week of and 2 weeks before collection were negatively correlated with average pupae per container, while bed canopy use, unemployment, container water volume, and the interaction between large solid collection and rainfall 2 weeks before the sampling event were positively correlated. Selection of these variables across other top candidate models with ΔAICc < 1 was robust, with the strongest effects from large solid collection and bed canopy use. The final container-level model explaining the characteristics of breeding sites found that contaminated water is positively correlated with Ae. aegypti pupae counts while breeding sites composed of car parts, furniture, sewerage parts, vases, ceramic material, glass material, metal material, and plastic material were all negatively correlated.ConclusionHaving access to municipal services like bulky item pickup was effective at reducing mosquito proliferation in households. Association of bed canopy use with higher mosquito densities is unexpected, and may be a consequence of large local mosquito populations or due to limited use or effectiveness of other vector control methods. The impact of rainfall on mosquito density is multifaceted, as it may both create new habitat and “wash out” existing habitat. Providing services and social/technical interventions focused on monitoring and eliminating productive breeding sites is important for reducing aquatic-stage mosquito densities in households at risk for Ae. aegypti-transmitted diseases.

scholarly journals Comparative Population Genetics of Two Korean Aedes Mosquito Species with Vector Potential based on Mitochondrial DNA

2021 ◽  
Author(s):  
Jiyeong Shin ◽  
Jongwoo Jung
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Vector Control ◽  
Endemic Species ◽  
Korean Peninsula ◽  
Mismatch Distribution ◽  
Mosquito Species ◽  
Mitochondrial Genes ◽  
Rapid Expansion ◽  
Number Of Individuals

Abstract Background: Mosquitoes of the genus Aedes are important invasive species contributing to the spread of chikungunya, dengue fever, yellow fever, Zika virus, and other dangerous vector-borne diseases. Aedes albopictus is native to southeast Asia with rapid expansion due to human activity, showing a wide distribution in the Korean peninsula. Aedes flavopictus is considered to be native to East Asia with a broad distribution in the region, including in the Korean peninsula. Gaining a better understanding of the genetic diversity of these species is critical for establishing strategies for disease prevention and vector control. Methods: We obtained DNA from 148 specimens of Ae. albopictus and 166 specimens of Ae. flavopictus in Korea, and amplified two mitochondrial genes (COI and ND5) to compare the genetic diversity and structure of the two species.Results: We obtained a 658-bp sequence of COI and a 423-bp sequence of ND5 from the two mosquito species. We found low diversity and an insignificant population genetic structure in Ae. albopictus, and high diversity and an insignificant structure in Ae. flavopictus for these two mitochondrial genes. Ae. albopictus had less haplotypes with respect to the number of individuals, and a slight mismatch distribution was confirmed. By contrast, Ae. flavopictus had a large number of haplotypes compared with the number of individuals, and a large unimodal-type mismatch distribution was confirmed. Although the genetic structure of both species was insignificant, Ae. flavopictus exhibited higher genetic diversity than Ae. albopictus.Conclusions: Ae. albopictus appears to be an introduced species, whereas Ae. flavopictus is an endemic species to the Korean peninsula, and the difference in genetic diversity between the two species is related to their adaptability and introduction history. As an endemic species, Ae. flavopictus is likely to have a larger population size than expected. Further studies on the genetic structure and diversity of these two mosquito species will provide useful data for vector control.

Role of spleen in integrated control of splanchnic vascular tone: physiology and pathophysiologyThis article is part of a Special Issue on Information Transfer in the Microcirculation.

2009 ◽  
Vol 87 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Shereen M. Hamza ◽  
Susan Kaufman
Keyword(s):  
Septic Shock ◽  
Portal Hypertension ◽  
Information Transfer ◽  
Integrated Control ◽  
Sympathetic Nerves ◽  
Preliminary Evidence ◽  
Fluid Extravasation ◽  
Key Factor ◽  
Renal Vascular ◽  
Physiologic Regulation

Aside from its established immunologic and hematologic functions, the spleen also plays an important role in cardiovascular regulation. This occurs through changes in intrasplenic microvascular tone, as well as through splenic neurohormonal modulation of the renal and mesenteric vascular beds. Splenic regulation of blood volume occurs predominantly through fluid extravasation from the splenic circulation into lymphatic reservoirs; this is controlled by direct modulation of splenic pre- and postcapillary resistance by established physiologic agents such as atrial natriuretic peptide (ANP), nitric oxide (NO), and adrenomedullin (ADM). In addition to physiologic fluid regulation, splenic extravasation is a key factor in the inability to maintain adequate intravascular volume in septic shock. The spleen also controls renal microvascular tone through reflex activation of the splenic afferent and renal sympathetic nerves. This splenorenal reflex not only contributes to the physiologic regulation of blood pressure, but also contributes to the cardiovascular dysregulation associated with both septic shock and portal hypertension. In septic shock, the splenorenal reflex protectively limits splenic extravasation and potentially promotes renal sodium and water reabsorption and release of the vasoconstrictor angiotensin II; this function is eventually overwhelmed as shock progresses. In portal hypertension, on the other hand, the splenorenal reflex-mediated reduction in renal vascular conductance exacerbates sodium and water retention in the kidneys and may eventually contribute to renal dysfunction. Preliminary evidence suggests that the spleen also may play a role in the hemodynamic complications of portal hypertension via neurohormonal modulation of the mesenteric vascular bed. Lastly, the spleen itself may be a source of a vasoactive factor.

scholarly journals Plant Natural Products for the Control of Aedes aegypti: The Main Vector of Important Arboviruses

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3484 ◽  
Author(s):  
Maíra Rosato Silveiral Silvério ◽  
Laila Salmen Espindola ◽  
Norberto Peporine Lopes ◽  
Paulo Cézar Vieira
Keyword(s):  
Natural Products ◽  
Secondary Metabolites ◽  
Aedes Aegypti ◽  
Vector Control ◽  
Chemical Constituents ◽  
Mosquito Species ◽  
Mechanisms Of Action ◽  
Control Applications ◽  
Lower Toxicity ◽  
Plant Natural Products

The mosquito species Aedes aegypti is one of the main vectors of arboviruses, including dengue, Zika and chikungunya. Considering the deficiency or absence of vaccines to prevent these diseases, vector control remains an important strategy. The use of plant natural product-based insecticides constitutes an alternative to chemical insecticides as they are degraded more easily and are less harmful to the environment, not to mention their lower toxicity to non-target insects. This review details plant species and their secondary metabolites that have demonstrated insecticidal properties (ovicidal, larvicidal, pupicidal, adulticidal, repellent and ovipositional effects) against the mosquito, together with their mechanisms of action. In particular, essential oils and some of their chemical constituents such as terpenoids and phenylpropanoids offer distinct advantages. Thiophenes, amides and alkaloids also possess high larvicidal and adulticidal activities, adding to the wealth of plant natural products with potential in vector control applications.

scholarly journals Molecular Characterization of Culturable Aerobic Bacteria in the Midgut of Field-Caught Culex tritaeniorhynchus, Culex gelidus, and Mansonia annulifera Mosquitoes in the Gampaha District of Sri Lanka

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Nayana Gunathilaka ◽  
Koshila Ranasinghe ◽  
Deepika Amarasinghe ◽  
Wasana Rodrigo ◽  
Harendra Mallawarachchi ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Vector Control ◽  
Control Strategies ◽  
Mosquito Species ◽  
Diversity Indices ◽  
Plate Count ◽  
Adult Mosquito ◽  
Relative Distribution ◽  
Bacterial Isolates ◽  
Culex Tritaeniorhynchus

Background. Larval and adult mosquito stages harbor different extracellular microbes exhibiting various functions in their digestive tract including host-parasite interactions. Midgut symbiotic bacteria can be genetically exploited to express molecules within the vectors, altering vector competency and potential for disease transmission. Therefore, identification of mosquito gut inhabiting microbiota is of ample importance before developing novel vector control strategies that involve modification of vectors. Method. Adult mosquitoes of Culex tritaeniorhynchus, Culex gelidus, and Mansonia annulifera were collected from selected Medical Officer of Health (MOH) areas in the Gampaha district of Sri Lanka. Midgut lysates of the field-caught non-blood-fed female mosquitoes were cultured in Plate Count Agar medium, and Prokaryotic 16S ribosomal RNA partial genes of the isolated bacteria colonies were amplified followed by DNA sequencing. Diversity indices were used to assess the diversity and richness of the bacterial isolates in three mosquito species. The distribution pattern of bacterial isolates between different mosquito species was assessed by Distance-Based Redundancy Analysis (dbRDA). Results. A total of 20 bacterial species (Staphylococcus pasteuri, Bacillus megaterium, Staphylococcus cohnii, Pantoea dispersa, Staphylococcus chromogenes, Bacillus aquimaris, Staphylococcus arlettae, Staphylococcus sciuri, Staphylococcus warneri, Moraxella osloensis, Enterobacter sp., Klebsiella michiganensis, Staphylococcus hominis, Staphylococcus saprophyticus, Streptomyces sp., Bacillus niacin, Cedecea neteri, Micrococcus luteus, Lysinibacillus sphaericus, and Bacillus licheniformis) were identified. All of these species belonged to three phyla, Proteobacteria, Firmicutes, and Actinobacteria, out of which phylum Firmicutes (71.1%) was the most prominent. The least number of species was recorded from Actinobacteria. The relative distribution of midgut microbes in different mosquito species differed significantly among mosquito species (Chi-square, χ2=486.091; df=36; P≤0.001). Midgut microbiota of Cx. tritaeniorhynchus and Cx. gelidus indicated a similarity of 21.51%, while Ma. annulifera shared a similarity of 6.92% with the cluster of above two species. The gut microbiota of Cx. tritaeniorhynchus was also significantly more diverse and more evenly distributed compared to Ma. annulifera. Simpson’s diversity, Margalef’s diversity, and Menhinick’s diversity indices were higher in Cx. gelidus. Of the recorded species, P. dispersa and strains of nonpathogenic species in Bacillaceae family (B. megaterium, B. niacini, B. licheniformis, and L. sphaericus) can be recommended as potential candidates for paratransgenesis. Conclusion. The relative distribution of midgut microbes in different mosquito species differed significantly among the three studied adult mosquito species. The present data strongly encourage further investigations to explore the potential usage of these microbes through paratransgenic approach for novel eco-friendly vector control strategies.

scholarly journals Surveillance of mosquitoes (Diptera: Culicidae) in Rajshahi, Bangladesh

2019 ◽  
Vol 6 (2) ◽  
pp. 329-336
Author(s):  
Md Tanvir Anjum Anik ◽  
Thahsin Farjana
Keyword(s):  
Public Health ◽  
Mosquito Species ◽  
Water Bodies ◽  
Polluted Water ◽  
Agricultural Fields ◽  
Light Traps ◽  
Anopheles Species ◽  
Breeding Sites ◽  
Arthropod Vectors ◽  
The World

Mosquitoes are considered the most important arthropod vectors in the world. Mosquito borne diseases are major public health problems in most of tropical and subtropical countries. An investigation was performed at Bagha upazila in Rajshahi district to identify the mosquito species and their breeding sites at the study area. Adult mosquitoes were collected by insect collecting net, light traps and human bait method and larvae were collected by dipper, mug, ladle spoon and dropper. A total of 1947 adult mosquitoes and 1376 larvae were collected and identified. Total ten species of adult mosquitoes and nine species of larvae under two genera were identified. The collected mosquitoes were belonging to two genera- Anopheles (An.) and Culex (Cx.). The identified species were Cx. quinquefasciatus, Cx. bitaeniorhynchus, Cx. tritaeniorhynchus, Cx. gelidus, Cx. pseudovishnui, Cx. whitmorei, Cx. fuscanus, Cx. fuscocephala, An. aconitus, An. vagus and An. barbirostris. In both cases of larvae and adult mosquitoes, Culex was found more prevalent than Anopheles. In case of larvae the prevalence was 75.8% and 24.2%, and in case of adult it was 71.2% and 28.8% for Culex and Anopheles, respectively. Among the all identified mosquitoes, Cx. quinquefasciatus showed the highest abundance in both cases of larval (23.5%) and adult mosquitoes (25.2%). From the survey it has been apparent that the Culex species may prefer the polluted water bodies in the locality like households, dairy sheds and drains whereas Anopheles species may prefer agricultural fields, and dairy sheds. This study will help to detect the breeding sites of mosquitoes in study areas and to take necessary steps to control mosquitoes and mosquito borne diseases. Res. Agric., Livest. Fish.6(2): 329-336, August 2019

Caractérisation écologique des milieux humides à larves de moustiques (Culicides) de la région subarctique continentale d'Opinaca (territoire de la Baie de James, Québec)

1978 ◽  
Vol 56 (11) ◽  
pp. 2377-2387 ◽  
Author(s):  
Yves Mailhot ◽  
Alain Maire
Keyword(s):  
Mosquito Species ◽  
Riparian Areas ◽  
Culex Restuans ◽  
Breeding Sites ◽  
Qualitative And Quantitative ◽  
Salix Planifolia ◽  
Quantitative Analyses ◽  
Aedes Communis ◽  
Culex Territans

Twenty mosquito species were collected in a low-subarctic area located between Eastmain River and Petit-Opinaca Lake, Quebec (52°15′ N, 76°38′ W). Qualitative and quantitative analyses of larval mosquito populations identified 20 ecological units that served as larval breeding sites. The data revealed typical larval associations such as Aedes canadensis – Aedes decticus, characteristic of the open bog series, Aedes communis – Aedes pionips of alder–willow groves (Salix planifolia – Alnus rugosa), Aedes intrudens and Aedes cinereus in flooded riparian areas. The ecology of species with summer larvae is also described: Culex restuans, Culex territans, Culiseta alaskaensis, and Culiseta impatiens.

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