bims-mosdis 2021-11-14 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2021‒11‒14
twenty papers selected by
Richard Halfpenny
Staffordshire University

The effects of temephos, permethrin and malathion selection on the fitness and fecundity of Aedes aegypti.
Mosquito species (Diptera: culicidae) collected after tropical storm cristobal in Merida, Yucatan, South-east Mexico.
First Record of Natural Transovarial Transmission of Dengue Virus in Aedes albopictus from Cuba.
Impact of extrinsic incubation temperature on natural selection during Zika virus infection of Aedes aegypti and Aedes albopictus.
Does the roof type of a house influence the presence of adult Anopheles stephensi, urban malaria vector? - evidence from a few slum settings in Chennai, India.
An unwanted companion reaches the country: the first record of the alien mosquito Aedes japonicus japonicus (Theobald, 1901) in Slovakia.
Technical Workflow Development for Integrating Drone Surveys and Entomological Sampling to Characterise Aquatic Larval Habitats of Anopheles funestus in Agricultural Landscapes in Côte d'Ivoire.
Effect of Different Wall Surface Coverage With Deltamethrin-Treated Netting on the Reduction of Indoor-Biting Anopheles Mosquitoes (Diptera: Culicidae).
Community awareness and experiences of health workers concerning mosquito-borne viral diseases in selected districts of Gambella Region, Southwestern Ethiopia.
The invasive Korean bush mosquito Aedes koreicus (Diptera: Culicidae) in Germany as of 2020.
Modified mosquitoes result in 77% fewer Indonesian dengue cases.
Deltamethrin Microencapsulation in Emulsion Paint Binder and Its Long-Term Efficacy Against Dengue Vector Aedes aegypti.
Lineage Divergence and Vector-Specific Adaptation Have Driven Chikungunya Virus onto Multiple Adaptive Landscapes.
Utilization of the castor seed cake (biowaste) for mosquito vector control.
Behavior of Aedes albifasciatus (Diptera: Culicidae) larvae from eggs with different dormancy times and its relationship with parasitism by Strelkovimermis spiculatus (Nematoda: Mermithidae).
The essential oil of Schinus terebinthifolius and its nanoemulsion and isolated monoterpenes: Investigation of their activity against Culex pipiens with insights into the adverse effects on non-target organisms.
Structure of Aedes aegypti procarboxypeptidase B1 and its binding with Dengue virus for controlling infection.
Insecticide-treated livestock: a potential One Health approach to malaria control in Africa.
Emergence of West Nile Virus Lineage-2 in Resident Corvids in Istanbul, Turkey.
Malaria Epidemiology Along the Indian Districts Bordering Bhutan and Implications for Malaria Elimination in the Region.

Med Vet Entomol. 2021 Nov 09.

The effects of temephos, permethrin and malathion selection on the fitness and fecundity of Aedes aegypti.

K Gleave, F Mechan, L J Reimer.

  The recent scale-up of insecticide use has led to the rapid spread of insecticide resistance (IR) in mosquito populations across the world. Previous work has suggested that IR mechanisms could influence mosquito life-history traits, leading to alterations in fitness and key physiological functions. This study investigates to what extent mosquito fitness may be affected in a colony of Aedes aegypti after selection with temephos, permethrin or malathion insecticides. We measured immature development, sex ratio, adult longevity, energetic reserves under different rearing conditions and time points, ingested bloodmeal volume, mosquito size, male and female reproductive fitness and flight capability in the unexposed offspring of the three selected strains and unselected strain. We found that insecticide selection does have an impact on mosquito fitness traits in both male and female mosquitoes, with our temephos-exposed strain showing the highest immature development rates, improved adult survival, larger females under crowded rearing and increased sperm number in males. In contrast, this strain showed the poorest reproductive success, demonstrating that insecticide selection leads to trade-offs in life-history traits, which have the potential to either enhance or limit disease transmission potential.

Keywords:  Energetic resources; flight; insecticide resistance; larvicide; life-history parameters; mosquito

DOI:  https://doi.org/10.1111/mve.12551
Int J Trop Insect Sci. 2021 Oct 29. 1-6

Mosquito species (Diptera: culicidae) collected after tropical storm cristobal in Merida, Yucatan, South-east Mexico.

Juan Navarrete-Carballo, Wilberth Bibiano-Marín, Jorge Palacio-Vargas, Herón Huerta-Jiménez, Marco Torres-Castro, Carlos Arisqueta-Chable, Anuar Medina-Barreiro, Henry Puerta-Guardo, Azael Che-Mendoza, Abdiel Martin-Park, Pablo Manrique-Saide.

  After the tropical storm Cristobal, we performed special adult entomological collections in the peri-domicile of 35 houses from 25 neighborhoods of Mérida, Yucatan, Mexico in response to complaints from the community about an increased nuisance due to an abundance of mosquitoes. A total of 1,275 specimens from four genera and 13 species were collected: Aedes taeniorhynchus (92%), Culex quinquefasciatus (72%), Aedes aegypti (72%), Psorophora mexicana (36%), Psorophora cyanescens (32%), Aedes scapularis (24%), Culex nigripalpus (24%), Aedes albopictus (8%), Psorophora ferox (4%), Haemagogus equinus (4%), Aedes trivittatus (4%), Culex coronator (4%), Culex iolambdis (4%). From these collections, the increased mosquito nuisance was mainly the result of invasive species such as Aedes taeniorhynchus and Psorophora. City wide, vehicle mounted ULV spraying was performed by the MoH and the municipality of Merida to control adult mosquito populations. We report Culex iolambdis for the first time in Merida and Psorophora mexicana for the state of Yucatan.

Keywords:  Mexico; Mosquitoes; Surveillance; Tropical storm

DOI:  https://doi.org/10.1007/s42690-021-00679-1
Am J Trop Med Hyg. 2021 Nov 08. pii: tpmd210710. [Epub ahead of print]

First Record of Natural Transovarial Transmission of Dengue Virus in Aedes albopictus from Cuba.

Luis Augusto Piedra, Liss Claudia Martínez, Armando Ruiz, Juan Ramón Vázquez, María Guadalupe Guzmán, Jorge Rey, Juan Andres Bisset.

Transovarial transmission (TOT) of dengue virus (DENV) in Aedes spp. is an important mechanism for DENV maintenance in nature and may be important in initiating outbreaks. The objective of this study was to explore the occurrence of TOT in wild Aedes albopictus populations in Cuba. Mosquito larvae were collected in Cotorro municipality, Havana, Cuba, and identified to species. Fifteen pools of Ae. albopictus each containing 30 larvae were processed for DENV detection by using conventional RT-PCR and nested PCR. Four out of 15 pools processed were positive for DENV-3, but no other DENV serotype was detected. This is the first time TOT of DENV detected in Cuban field populations of Ae. albopictus, and this suggests that this species may be an important vector of DENV in Cuba.

DOI: https://doi.org/10.4269/ajtmh.21-0710
PLoS Pathog. 2021 Nov 09. 17(11): e1009433

Impact of extrinsic incubation temperature on natural selection during Zika virus infection of Aedes aegypti and Aedes albopictus.

Reyes A Murrieta, Selene M Garcia-Luna, Deedra J Murrieta, Gareth Halladay, Michael C Young, Joseph R Fauver, Alex Gendernalik, James Weger-Lucarelli, Claudia Rückert, Gregory D Ebel.

Arthropod-borne viruses (arboviruses) require replication across a wide range of temperatures to perpetuate. While vertebrate hosts tend to maintain temperatures of approximately 37°C-40°C, arthropods are subject to ambient temperatures which can have a daily fluctuation of > 10°C. Temperatures impact vector competence, extrinsic incubation period, and mosquito survival unimodally, with optimal conditions occurring at some intermediate temperature. In addition, the mean and range of daily temperature fluctuations influence arbovirus perpetuation and vector competence. The impact of temperature on arbovirus genetic diversity during systemic mosquito infection, however, is poorly understood. Therefore, we determined how constant extrinsic incubation temperatures of 25°C, 28°C, 32°C, and 35°C control Zika virus (ZIKV) vector competence and population dynamics within Aedes aegypti and Aedes albopictus mosquitoes. We also examined fluctuating temperatures which better mimic field conditions in the tropics. We found that vector competence varied in a unimodal manner for constant temperatures peaking between 28°C and 32°C for both Aedes species. Transmission peaked at 10 days post-infection for Aedes aegypti and 14 days for Aedes albopictus. Conversely, fluctuating temperature decreased vector competence. Using RNA-seq to characterize ZIKV population structure, we identified that temperature alters the selective environment in unexpected ways. During mosquito infection, constant temperatures more often elicited positive selection whereas fluctuating temperatures led to strong purifying selection in both Aedes species. These findings demonstrate that temperature has multiple impacts on ZIKV biology, including major effects on the selective environment within mosquitoes.

DOI: https://doi.org/10.1371/journal.ppat.1009433
Parasitol Res. 2021 Nov 13.

Does the roof type of a house influence the presence of adult Anopheles stephensi, urban malaria vector? - evidence from a few slum settings in Chennai, India.

Sangamithra Ravishankaran, Aswin Asokan, N A Johnson Amala Justin, Shalu Thomas, Vasna Joshua, Manu Thomas Mathai, Alex Eapen.

  In an urban setting, it is a difficult task to collect adult Anopheles stephensi, unlike the immature stages, due to various reasons. A longitudinal study was undertaken from January 2016 to April 2017, with CDC light traps to collect adult Anopheles stephensi and other mosquito species in houses located in a few slums of Chennai, India. A total of 203 trap collections were made indoors from human dwellings having different roof types, as well as outdoors. Three to four trap collections were made at night (18:00 to 06:00 h) once a week. Overall, Culex quinquefasciatus (64%) was the predominant mosquito species captured, followed by An. stephensi (24%). In 98 of the 203 trap collections (48.3%), at least one female An. stephensi was trapped. In all, 224 female An. stephensi were trapped, of which the majority were collected during monsoon and winter seasons. Compared to outdoors, 10% more An. stephensi, the majority of them unfed, were collected indoors, with relatively more contribution coming from asbestos-roofed houses (71.4%), followed by thatched-roof houses (47.3%). Overall, 2.2% positivity for Plasmodium vivax was detected in An. stephensi through Circumsporozoite-ELISA. Binary logistic regression model indicated that season (winter and monsoon), asbestos-roofed dwelling, lesser number of rooms in a house, and more members in a family were significant predictor variables for the odds of trapping an An. stephensi. The study brought out significant factors associated with the presence of An. stephensi in urban slums setting in Chennai, where malaria is declining. The findings would help in devising targeted, effective vector control interventions for malaria elimination in urban settings.

Keywords:  Anopheles stephensi; CDC light trap; House roof type; Malaria vector; Urban slum; Vector incrimination

DOI:  https://doi.org/10.1007/s00436-021-07376-5
Parasit Vectors. 2021 Nov 12. 14(1): 572

An unwanted companion reaches the country: the first record of the alien mosquito Aedes japonicus japonicus (Theobald, 1901) in Slovakia.

Viktória Čabanová, Kristína Boršová, Marek Svitok, Jozef Oboňa, Ivana Svitková, Eva Barbušinová, Tomáš Derka, Monika Sláviková, Boris Klempa.

  BACKGROUND: Invasive mosquitoes of the genus Aedes are quickly spreading around the world. The presence of these alien species is concerning for both their impact on the native biodiversity and their high vector competence. The surveillance of Aedes invasive mosquito (AIM) species is one of the most important steps in vector-borne disease control and prevention.METHODS: In 2020, the monitoring of AIM species was conducted in five areas (Bratislava, Zvolen, Banská Bystrica, Prešov, Košice) of Slovakia. The sites were located at points of entry (border crossings with Austria and Hungary) and in the urban and rural zones of cities and their surroundings. Ovitraps were used at the majority of sites as a standard method of monitoring. The collected specimens were identified morphologically, with subsequent molecular identification by conventional PCR (cox1) and Sanger sequencing. The phylogenetic relatedness of the obtained sequences was inferred by the maximum likelihood (ML) method. The nucleotide heterogeneity of the Slovak sequences was analysed by the index of disparity.
RESULTS: A bush mosquito, Aedes japonicus japonicus, was found and confirmed by molecular methods in three geographically distant areas of Slovakia-Bratislava, Zvolen and Prešov. The presence of AIM species is also likely in Košice; however, the material was not subjected to molecular identification. The nucleotide sequences of some Slovak strains confirm their significant heterogeneity. They were placed in several clusters on the ML phylogenetic tree. Moreover, Ae. j. japonicus was discovered in regions of Slovakia that are not close to a point of entry, where the mosquitoes could find favourable habitats in dendrothelms in city parks or forests.
CONCLUSION: Despite being a first record of the Ae. j. japonicus in Slovakia, our study indicates that the established populations already exist across the country, underlining the urgent need for intensified surveillance of AIM species as well as mosquito-borne pathogens.

Keywords:  Aedes invasive mosquitoes; Aedes japonicus japonicus; Alien species; Asian bush mosquito; Central Europe; Culicidae; Hulecoeteomyia japonica

DOI:  https://doi.org/10.1186/s13071-021-05062-0
J Environ Public Health. 2021 ;2021 3220244

Technical Workflow Development for Integrating Drone Surveys and Entomological Sampling to Characterise Aquatic Larval Habitats of Anopheles funestus in Agricultural Landscapes in Côte d'Ivoire.

Isabel Byrne, Kallista Chan, Edgar Manrique, Jo Lines, Rosine Z Wolie, Fedra Trujillano, Gabriel Jimenez Garay, Miguel Nunez Del Prado Cortez, Hugo Alatrista-Salas, Eleanore Sternberg, Jackie Cook, Raphael N'Guessan, Alphonsine Koffi, Ludovic P Ahoua Alou, Nombre Apollinaire, Louisa A Messenger, Mojca Kristan, Gabriel Carrasco-Escobar, Kimberly Fornace.

Land-use practices such as agriculture can impact mosquito vector breeding ecology, resulting in changes in disease transmission. The typical breeding habitats of Africa's second most important malaria vector Anopheles funestus are large, semipermanent water bodies, which make them potential candidates for targeted larval source management. This is a technical workflow for the integration of drone surveys and mosquito larval sampling, designed for a case study aiming to characterise An. funestus breeding sites near two villages in an agricultural setting in Côte d'Ivoire. Using satellite remote sensing data, we developed an environmentally and spatially representative sampling frame and conducted paired mosquito larvae and drone mapping surveys from June to August 2021. To categorise the drone imagery, we also developed a land cover classification scheme with classes relative to An. funestus breeding ecology. We sampled 189 potential breeding habitats, of which 119 (63%) were positive for the Anopheles genus and nine (4.8%) were positive for An. funestus. We mapped 30.42 km2 of the region of interest including all water bodies which were sampled for larvae. These data can be used to inform targeted vector control efforts, although its generalisability over a large region is limited by the fine-scale nature of this study area. This paper develops protocols for integrating drone surveys and statistically rigorous entomological sampling, which can be adjusted to collect data on vector breeding habitats in other ecological contexts. Further research using data collected in this study can enable the development of deep-learning algorithms for identifying An. funestus breeding habitats across rural agricultural landscapes in Côte d'Ivoire and the analysis of risk factors for these sites.

DOI: https://doi.org/10.1155/2021/3220244
J Med Entomol. 2021 Nov 09. 58(6): 2299-2307

Effect of Different Wall Surface Coverage With Deltamethrin-Treated Netting on the Reduction of Indoor-Biting Anopheles Mosquitoes (Diptera: Culicidae).

Krajana Tainchum, Michael J Bangs, Sunaiyana Sathantriphop, Theeraphap Chareonviriyaphap.

  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.

Keywords:   Anopheles dirus s.l; Anopheles minimus s.l; Thailand; deltamethrin-treated netting; experimental hut

DOI:  https://doi.org/10.1093/jme/tjab095
Infect Ecol Epidemiol. 2021 ;11(1): 1988453

Community awareness and experiences of health workers concerning mosquito-borne viral diseases in selected districts of Gambella Region, Southwestern Ethiopia.

Getahun Asebe, Gezahegne Mamo, Barbara Wieland, Girmay Medhin, Getachew Tilahun, Woldaregay Erku Abegaz, Mengistu Legesse.

  In this study, we assessed community awareness and experiences of health workers about mosquito-borne viral diseases in selected districts of the Gambella Region, South Western Ethiopia. A community and health facility-based qualitative study involving 11 focus group discussions (FGDs) with community dmembers and two FGDs with health workers was conducted between November 2017 to January 2018. A total of 122 community members and 16 health workers participated in the study. All the discussants mentioned malaria, typhoid fever, unknown causes of diarrhea and skin diseases as the major public health problems in the area. Using pictures of Anopheles and Aedes mosquitoes, participants confirmed that both mosquitoes are present in the area. They identified Anopheles as the vector of malaria. However, community discussants could not mention the name of a disease that can be transmitted by Aedes mosquito though they mentioned that Aedes mosquito bites both humans and animals during the day time in forest areas and causes skin itching to humans. Meanwhile, community participants from Pakag, a village bordering South Sudan, expressed concern that Aedes mosquito can cause a malaria-like disease which can kill within a few days. Health workers from Itang health center described that in 2016, an outbreak of an unknown disease that causes fever and jaundice occurred and killed seven individuals in a village called Akula, which is closer to a South Sudan refugee camp. Overall, the findings showed that community members and health workers in the area do not have adequate information on mosquito-borne viral diseases. Creating awareness, improving laboratory services and further epidemiological studies would be important for early warning and preparedness for outbreaks in the area.

Keywords:  Ethiopia; Qualitative; a mosquito-transmitted disease; arboviruses; community participation

DOI:  https://doi.org/10.1080/20008686.2021.1988453
Parasit Vectors. 2021 Nov 12. 14(1): 575

The invasive Korean bush mosquito Aedes koreicus (Diptera: Culicidae) in Germany as of 2020.

Nicolas Hohmeister, Doreen Werner, Helge Kampen.

  BACKGROUND: The Korean bush mosquito Aedes koreicus was recently reported to have established a population in western Germany (Wiesbaden) in 2016. The species is difficult to distinguish morphologically from its close relative, the invasive Japanese bush mosquito Ae. japonicus, which is already widely distributed in many parts of Germany, including the area colonised by Ae. koreicus. Genetic confirmation of morphologically identified "Ae. japonicus" collection material, however, had only been done exceptionally before the German Ae. koreicus population became known.METHODS: Dried archived "Ae. japonicus" specimens both from the municipality of Wiesbaden and from deliberately and randomly selected distribution sites all over Germany were re-examined morphologically and genetically for admixture by Ae. koreicus. Moreover, cemeteries in the greater Wiesbaden area were sampled in 2019 and 2020 to check for Ae. koreicus spread. Korean and Japanese bush mosquitoes submitted to the German citizen science mosquito monitoring scheme "Mueckenatlas" in 2019 and 2020 were also subjected to particularly thorough species identification. The ND4 DNA sequences generated in this study in the context of species identification were phylogenetically compared to respective GenBank entries of Ae. koreicus. As a by-product, several genetic markers were evaluated for their suitability to identify Ae. koreicus.
RESULTS: Aedes koreicus specimens could be identified in mosquito collection material and submissions from Wiesbaden from 2015 onwards, suggesting establishment to have happened in the same year as Ae. japonicus establishment. Detections of Ae. koreicus from 2019 and 2020 in Wiesbaden indicate a negligible enlargement of the populated area as described for 2018. Two Ae. koreicus specimens were also submitted from the city of Munich, southern Germany, in 2019 but further specimens could not be identified during immediate local inspections. Comparison of ND4 sequences generated in this and other studies demonstrate a high degree of homology, suggesting that this DNA region is not informative enough for clarification of origins and relationships of Ae. koreicus populations. For genetic identification of Ae. koreicus, PCR primers used for classical CO1 barcoding were found to lead to mismatches and produce no or incorrect amplicons. Alternative CO1 primers or a validated ND4 marker should be used instead.
CONCLUSIONS: Aedes koreicus is probably introduced into Germany every now and then but rarely succeeds in becoming established. As with most European populations, the German population is characterised by a limited expansion tendency. Since Ae. koreicus is a potential vector, however, Asian bush mosquitoes found at new places should be examined quite carefully and known distribution areas of Ae. japonicus regularly checked for the presence of Ae. koreicus.

Keywords:  Aedes japonicus; Cemetery; Distribution; Genetic identification; Germany; Hulecoeteomyia koreica; Invasive mosquito species; Mueckenatlas

DOI:  https://doi.org/10.1186/s13071-021-05077-7
Explore (NY). 2021 Oct 29. pii: S1550-8307(21)00224-X. [Epub ahead of print]

Modified mosquitoes result in 77% fewer Indonesian dengue cases.

Susie Demarinis.

DOI: https://doi.org/10.1016/j.explore.2021.10.009
Front Public Health. 2021 ;9 686122

Deltamethrin Microencapsulation in Emulsion Paint Binder and Its Long-Term Efficacy Against Dengue Vector Aedes aegypti.

B N Acharya, Rajkumar Ahirwar, Sunil Dhiman, Kavita Yadav, Pratibha Pandey, Devanathan Sukumaran.

  Various control interventions have been effective in the control of arthropod vectors to a certain extent; still, sustained vector control is an existing problem globally. Insecticide-based formulations have been found to be useful, however the proper delivery of active molecules to target vectors is important. Currently, synthetic pyrethroid deltamethrin (DM) has been microencapsulated in the emulsion paint binder and evaluated for long-term effectiveness against dengue vector Aedes aegypti. Different compositions of emulsion binder were prepared by varying the content of monomer and DM. A selection was made for the composition yielding the best combination of properties like solid content, intrinsic viscosity, and DM content. Developed formulation was tested against laboratory-reared and pathogen-free Ae. aegypti mosquitoes. Encapsulation of DM in emulsion binder during polymerization showed a uniform distribution. The optimized formulation was stable and did not have a considerable plasticizing effect. Scanning electron microscopy revealed that grain-like micro crystals of DM and surfactant sodium lauryl sulfate (SDS) were uniformly distributed on the formulation surface. The best optimized formulation was highly effective against dengue vector Ae. aegypti and found to provide efficacy for up to 18 months of application. The knockdown time (KDT) values KDT10 and KDT50 were 7.4 min (95% CI: 5.6-9.1) and 22.1 min (95% CI: 19.7-24.3) respectively, whereas 24 h corrected mortality was 90% (95% CI: 82.5-97.5) after 18 months of application (T18). The probit model used to determine knockdown values did not deviate from the linearity and displayed normal distribution of knockdown % with time for different formulations (p ≥ 0.1). Presently developed DM microencapsulated emulsion binder was stable, smooth, and uniform. The binder displayed excellent anti-insect property and was capable of providing long-term effectiveness against dengue vectors Ae. aegypti. Such a formulation after field-scale evaluation could be very useful in attaining long-term protection from arthropod vectors.

Keywords:  Aedes aegypti; binder; deltamethrin; dengue vector; emulsion; insecticidal paint

DOI:  https://doi.org/10.3389/fpubh.2021.686122
mBio. 2021 Nov 09. e0273821

Lineage Divergence and Vector-Specific Adaptation Have Driven Chikungunya Virus onto Multiple Adaptive Landscapes.

Rubing Chen, Jessica A Plante, Kenneth S Plante, Ruimei Yun, Divya Shinde, Jianying Liu, Sherry Haller, Suchetana Mukhopadhyay, Scott C Weaver.

  Previous studies have shown that the adaptation of Indian Ocean lineage (IOL) chikungunya virus (CHIKV) strains for Aedes albopictus transmission was mediated by an E1-A226V substitution, followed by either a single substitution in E2 or synergistic substitutions in the E2 and E3 envelope glycoproteins. Here, we examined whether Asian lineage strains, including those that descended from the 2014 Caribbean introduction, are likely to acquire these A. albopictus-adaptive E2 substitutions. Because Asian lineage strains cannot adapt through the E1-A226V substitution due to an epistatic constraint, we first determined that the beneficial effect of these E2 mutations in IOL strains is independent of E1-A226V. We then introduced each of these E2 adaptive mutations into the Asian lineage backbone to determine if they improve infectivity for A. albopictus. Surprisingly, our results indicated that in the Asian lineage backbone, these E2 mutations significantly decreased CHIKV fitness in A. albopictus. Furthermore, we tested the effects of these mutations in Aedes aegypti and observed different results from those in A. albopictus, suggesting that mosquito species-specific factors that interact with the envelope proteins are involved in vector infection efficiency. Overall, our results indicate that the divergence between Asian lineage and IOL CHIKVs has led them onto different adaptive landscapes with differing potentials to expand their vector host range. IMPORTANCE Since its introduction into the Caribbean in October 2013, CHIKV has rapidly spread to almost the entire neotropical region. However, its potential to further spread globally, including into more temperate climates, depends in part on its ability to be transmitted efficiently by Aedes albopictus, which can survive colder winters than A. aegypti. We examined in an Asian lineage backbone A. albopictus-adaptive mutations that arose from 2005 to 2009 in Indian Ocean lineage (IOL) strains. Our results predict that the Asian CHIKV lineage now in the Americas will not readily adapt for enhanced A. albopictus transmission via the same mechanisms or adaptive mutations used previously by IOL strains. The vector species- and CHIKV lineage-specific effects caused by adaptive CHIKV envelope glycoprotein substitutions may elucidate our understanding of the mechanisms of mosquito infection and spread.

Keywords:  alphavirus; arbovirus; arthropod vectors; evolution; mosquito

DOI:  https://doi.org/10.1128/mBio.02738-21
Trop Parasitol. 2021 Jul-Dec;11(2):11(2): 102-107

Utilization of the castor seed cake (biowaste) for mosquito vector control.

Nisha Sogan, Smriti Kala, Neera Kapoor, P K Patanjali, B N Nagpal.

  The present work is related to the utilization of castor (Ricinus communis) seed cake, biowaste produced during the oil extraction of castor seeds, as efficient mosquitocidal composition against Aedes aegypti and Anopheles culicifacies. The efficacy of coil formulations was evaluated in the Peet Grady chamber and resulted in 90% and 100% knocked down and mortality against A. aegypti and A. Culicifacies, respectively. Further heavy metals' (Cr, Pb, Co, As, Cd, Cu, Mn, and Zn) analysis of the coil was performed using Inductively Coupled Plasma mass spectrometry and was compared with commercially available mosquito repellent coil. Heavy metal analysis revealed that commercial repellent coil had a higher content of heavy metals than the castor seed cake coil. Finding of the present research study indicates that castor seed cake coil has the potential to be used in mosquito vector control. Castor seed cake coil formulation will also open up avenues in future for sustainable utilization of the biowaste.

Keywords:  Biowaste; biopesticide; castor seed cake; coil; heavy metals; knocked down

DOI:  https://doi.org/10.4103/2229-5070.328691
Parasitol Res. 2021 Nov 11.

Behavior of Aedes albifasciatus (Diptera: Culicidae) larvae from eggs with different dormancy times and its relationship with parasitism by Strelkovimermis spiculatus (Nematoda: Mermithidae).

Cristian M Di Battista, Sylvia Fischer, Raúl E Campos.

  Aedine mosquitoes go through unfavorable periods as dormant eggs. However, extended dormancy times lead to a depletion of egg reserves, which might be partially compensated by changes in larval-feeding behavior. Changes in larval behavior may also be induced by parasitism by mermithids probably as a strategy to reduce the impact of the parasite on the host. The most abundant floodwater mosquito in southern South America is Aedes albifasciatus (Diptera: Culicidae), a species naturally parasitized by Strelkovimermis spiculatus (Nematoda: Mermithidae). This study aimed to evaluate the behavior of fourth-instar larvae of Ae. albifasciatus from eggs with 2, 4, and 6 months of dormancy, parasitized or not by S. spiculatus. To achieve this, eight categories of behavior were defined, and then, each individual was observed for 5 min, and its behaviors and their duration were recorded. The behaviors with the highest percentage of observation time were still (50.1%) and wriggle swimming (33.6%), while those with the lowest percentage of observation time were those involving active foraging (less than 8%). A great variability in the behaviors was observed among individuals within the same treatment. The type and duration of each behavior did not vary in relation to egg dormancy time or parasitism, but parasitism affected the level of larval activity. Parasitized larvae performed, on average, fewer behaviors than non-parasitized larvae. This result supports the hypothesis that S. spiculatus parasitism affects the behavior of Ae. albifasciatus larvae by reducing their level of activity.

Keywords:  Behavioral changes; Culicidae; Dormant eggs; Flood water mosquito; Host-parasite interactions; Mermithidae

DOI:  https://doi.org/10.1007/s00436-021-07371-w
Pest Manag Sci. 2021 Nov 13.

The essential oil of Schinus terebinthifolius and its nanoemulsion and isolated monoterpenes: Investigation of their activity against Culex pipiens with insights into the adverse effects on non-target organisms.

Gomah E Nenaah, Abdulrhman A Almadiy, Basma A Al-Assiuty, Mater H Mahnashi.

  BACKGROUND: The house mosquito, Culex pipiens L. is a harmful species widespread in urban zones and considered as the primary enzootic vector of West Nile arbovirus. The widespread insecticide resistance in mosquito populations and the environmental risks and toxicity hazards of chemical pesticides make them inadequate mosquito control strategy. Seeking ecofriendly mosquito control tools became a renewed demand.RESULTS: Herein, essential oil (EO) was hydrodistilled from the fruits of Brazilian pepper, Schinus terebinthifolius Raddi and analyzed using gas chromatography-flame ionization detection (GC-FID) and (GC-MS). Oil-in-water nanoemulsion (particle size 41.3 nm) was developed and characterized from EO using a green low energy approach. EO, its nanoemulsion and monoterpenes caused mosquitocidal, repellent and acetylcholinesterase inhibitory activities (AChE) against Cx. pipiens. A concentration of 30 μl/l of nanoemulsion caused 100% larval mortality after 24 h of exposure, while EO, d-limonene, and α-phelandrene at 60 μl/l caused 100, 92.4, and 88.2% larval mortality, respectively. LC50 's against larvae after 24 h ranged between 6.8 and 40.6 μl/l. Upon fumigation, a concentration of 15.0 μl/l of nanoemulsion killed 94.5% of adults after 24 h of exposure. LC50 's against adults ranged between 5.3 and 31.2 μl/l. EO products exhibited repellence activity at concentrations between 0.5 and 4.0 μl/cm2 . Test materials effectively inhibited AChE activity of mosquito and were safe toward the non-target aquatic organisms G. affinis and E. fetida and the earthworm, E. fetida.
CONCLUSION: There is a potential for using S. terebinthifolius EO, its nanoemulsion and monoterpenes as ecofriendly natural mosquitocides. This article is protected by copyright. All rights reserved.

Keywords:  Culex pipiens; Schinus terebinthifolius; bioactivity, biosafety; essential oil; nanoemulsion

DOI:  https://doi.org/10.1002/ps.6715
Life Sci Alliance. 2022 Jan;pii: e202101211. [Epub ahead of print]5(1):

Structure of Aedes aegypti procarboxypeptidase B1 and its binding with Dengue virus for controlling infection.

Edem Gavor, Yeu Khai Choong, Nikhil Kumar Tulsian, Digant Nayak, Fakhriedzwan Idris, Hariharan Sivaraman, Donald Heng Rong Ting, Alonso Sylvie, Yu Keung Mok, R Manjunatha Kini, J Sivaraman.

Metallocarboxypeptidases play critical roles in the development of mosquitoes and influence pathogen/parasite infection of the mosquito midgut. Here, we report the crystal structure of Aedes aegypti procarboxypeptidase B1 (PCPBAe1), characterized its substrate specificity and mechanism of binding to and inhibiting Dengue virus (DENV). We show that the activated PCPBAe1 (CPBAe1) hydrolyzes both Arg- and Lys-substrates, which is modulated by residues Asp251 and Ser239 Notably, these residues are conserved in CPBs across mosquito species, possibly required for efficient digestion of basic dietary residues that are necessary for mosquito reproduction and development. Importantly, we characterized the interaction between PCPBAe1 and DENV envelope (E) protein, virus-like particles, and infectious virions. We identified residues Asp18A, Glu19A, Glu85, Arg87, and Arg89 of PCPBAe1 are essential for interaction with DENV. PCPBAe1 maps to the dimeric interface of the E protein domains I/II (Lys64-Glu84, Val238-Val252, and Leu278-Leu287). Overall, our studies provide general insights into how the substrate-binding property of mosquito carboxypeptidases could be targeted to potentially control mosquito populations or proposes a mechanism by which PCPBAe1 binds to and inhibits DENV.

DOI: https://doi.org/10.26508/lsa.202101211
Trends Parasitol. 2021 Oct 29. pii: S1471-4922(21)00231-2. [Epub ahead of print]

Insecticide-treated livestock: a potential One Health approach to malaria control in Africa.

Paula Ruiz-Castillo, Cassidy Rist, Regina Rabinovich, Carlos Chaccour.

  New vector-control tools are urgently needed to reduce malaria in areas where there is significant transmission after deployment of indoor residual spraying (IRS) and insecticide treated nets. Insecticide-treated livestock (ITL) is a potential novel strategy by which zoophagic mosquitos are killed after feeding upon animals treated with an insecticide. Although there are several insecticide candidates in the pipeline with a wide efficacy range against mosquitos, additional field studies with epidemiological outcomes are required to test the impact of this intervention on malaria transmission. Insecticides under consideration have long been used in livestock to improve animal health and productivity, but each has food and environmental safety considerations. Therefore, moving ITL from a concept to implementation will require a One Health framework.

Keywords:  One Health; livestock; malaria; residual transmission; systemic insecticides

DOI:  https://doi.org/10.1016/j.pt.2021.09.006
Vector Borne Zoonotic Dis. 2021 Nov 08.

Emergence of West Nile Virus Lineage-2 in Resident Corvids in Istanbul, Turkey.

Ozge Erdogan Bamac, Utku Y Cizmecigil, Asli Mete, Aysun Yilmaz, Ozge Aydin, Hasan E Tali, Besim H Tali, Semaha G Yilmaz, Aydin Gurel, Nuri Turan, Serhat Ozsoy, Ezgi Vatansever Celik, Jean-Remy Sadeyen, Gleyder Roman-Sosa, Munir Iqbal, Juergen A Richt, Huseyin Yilmaz.

  West Nile fever is a vector-borne viral disease affecting animals and humans causing significant health and economic problems globally. This study was aimed at investigating circulating West Nile virus (WNV) strains in free-ranging corvids in Istanbul, Turkey. Brain, liver, and kidney were collected from corvids (n = 34) between June 2019 and April 2020 and analyzed for the presence of WNV-specific RNA by quantitative RT-PCR. In addition, histopathologic and immunohistochemical examinations were also performed. Samples found to be positive by qRT-PCR were partially sequenced. WNV-specific RNA was detected in 8 of 34 corvids analyzed, which included 7 hooded crows (Corvus cornix) and 1 Eurasian magpie (Pica pica). Phylogenetic analysis based on partial WNV sequences from the 8 WNV-positive corvids identified in this study revealed that all sequences clustered within the WNV lineage-2; they were at least 97% homologues to WNV lineage-2 sequences from Slovakia, Italy, Czechia, Hungary, Senegal, Austria, Serbia, Greece, Bulgaria, and Germany. WNV sequences showed a divergence (87.94-94.46%) from sequences reported from Romania, Central African Republic, South Africa, Madagascar, Israel, and Cyprus, which clustered into a different clade of WNV lineage-2. Common histopathologic findings of WNV-positive corvids included lymphoplasmacytic hepatitis, myocarditis, and splenitis. The liver and heart were found to be the tissues most consistently positive for WNV-specific antigen by immunohistochemistry, followed by the kidney and brain. This study demonstrates for the first time the existence of WNV virus belonging to the genetic lineage-2 in resident corvids in Istanbul, Turkey. We hypothesize that the WNV strains circulating in Istanbul are possibly the result of a spillover event from Europe. Since WNV is a zoonotic pathogen transmitted by mosquito vectors, the emergence of WNV in Istanbul also poses a risk to humans and other susceptible animals in this densely populated city and needs to be addressed by animal and public health authorities.

Keywords:  Istanbul; WNV lineage-2; West Nile virus; corvids; histopathology; phylogeny

DOI:  https://doi.org/10.1089/vbz.2021.0010
Am J Trop Med Hyg. 2021 Nov 08. pii: tpmd210513. [Epub ahead of print]

Malaria Epidemiology Along the Indian Districts Bordering Bhutan and Implications for Malaria Elimination in the Region.

Sanjeev Kumar Gupta, Poonam Saroha, Kuldeep Singh, Rekha Saxena, Keshab Barman, Avdhesh Kumar, Amit Sharma.

It is important for malaria-endemic countries to address malaria control across international borders, and in particular to prioritize appropriate rapid diagnosis, treatment, and surveillance. Bhutan and India aim to achieve malaria elimination by 2023 and 2030, respectively. Malaria elimination along the Indo-Bhutan border is of common concern. We delineated malaria epidemiology along the border to provide a blueprint for focusing malaria control efforts in key foci within this region. Epidemiological data from 2015 to 2019 were analyzed, as the most drastic reductions in malaria burden across most parts of India were witnessed in this time frame. Several areas of concern include low surveillance in most border districts, favorable climatic conditions for perennial malaria transmission, and movement of potential parasite carriers because of the porous borders. India and Bhutan need to control the importation/exportation of malaria cases. We highlight the key foci of concern for which implementing tailor-made malaria control strategies may benefit both countries.

DOI: https://doi.org/10.4269/ajtmh.21-0513