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Mansonia are aggressive mosquito species that are abundant in aquatic ecosystems where the macrophyte plants occur. These mosquitoes are commonly found across the Amazon/Solimões River basin. However, little is known about the oviposition behavior of these species. In the present study, we registered observations on the oviposition activity of 3 species: Mansonia amazonensis , Ma. humeralis , and Ma . cf. titillans , in 5 species of macrophytes in the vicinities of the Madeira River, Porto Velho, State of Rondônia, Brazil. Overall, 197 egg batches were collected. A greater amount of egg batches was found in Salvinia molesta as compared with other macrophytes sampled. In addition, 2 new oviposition habitats were noted in Ludwigia helmintorrhiza and Limnobium spongia . These findings will be important to understand the reproductive dynamics of these mosquitoes in the Brazilian Amazon basin.

Mansonia (Diptera: Culicidae) are known to cause discomfort to the local populations of Amazon. Considering the fact that the effective control of these mosquitoes can only be obtained by understanding their ecology and behavior, entomological monitoring becomes essential. In view of this, mosquitoes of the genus Mansonia were collected by human landing catches (HLC) from 2015 to 2019, in four locations of Porto Velho, Rondônia, Brazil. The collections were performed inside and outside the homes, once in every four months, uninterrupted for 24 hr. Human bite indices/hour was used to analyze the hourly activity of the species for different seasons and environment (indoor and outdoor). Moreover, nonparametric Mann–Whitney tests were conducted to indicate if there were differences between exophagic and endophagic behavior. The seasonality of Mansonia species was also analyzed. Overall, 96,766 specimens were collected over five years of sampling. Mansonia titillans (Walker) was found to be the most abundant species (76.9%). The highest percentage of mosquitoes was collected in February (48.4%), followed by October (39.6%) and June (12.0%). The biting activity of the two most abundant species showed peak host seeking activity/behavior during twilight and night, more perceptible in the outdoor environment (peridomiciliary). In general, seasonality showed a tendency towards a reduction in the abundance of Mansonia in the years after 2015. Our results will be essential in the formulation of effective control methodology for Mansonia in the studied area.

Background The endosymbiont bacterium Wolbachia is maternally inherited and naturally infects some filarial nematodes and a diverse range of arthropods, including mosquito vectors responsible for disease transmission in humans. Previously, it has been found infecting most mosquito species but absent in Anopheles and Aedes aegypti . However, recently these two mosquito species were found to be naturally infected with Wolbachia . We report here the extent of Wolbachia infections in field-collected mosquitoes from Malaysia based on PCR amplification of the Wolbachia wsp and 16S rRNA genes. Methods The prevalence of Wolbachia in Culicinae mosquitoes was assessed via PCR with wsp primers. For some of the mosquitoes, in which the wsp primers failed to amplify a product, Wolbachia screening was performed using nested PCR targeting the 16S rRNA gene. Wolbachia sequences were aligned using Geneious 9.1.6 software, analyzed with BLAST, and the most similar sequences were downloaded. Phylogenetic analyses were carried out with MEGA 7.0 software. Graphs were drawn with GraphPad Prism 8.0 software. Results A total of 217 adult mosquitoes representing 26 mosquito species were screened. Of these, infections with Wolbachia were detected in 4 and 15 mosquito species using wsp and 16S rRNA primers, respectively. To our knowledge, this is the first time Wolbachia was detected using 16S rRNA gene amplification, in some Anopheles species (some infected with Plasmodium ), Culex sinensis , Culex vishnui , Culex pseudovishnui , Mansonia bonneae and Mansonia annulifera . Phylogenetic analysis based on wsp revealed Wolbachia from most of the mosquitoes belonged to Wolbachia Supergroup B. Based on 16S rRNA phylogenetic analysis, the Wolbachia strain from Anopheles mosquitoes were more closely related to Wolbachia  infecting Anopheles from Africa than from Myanmar. Conclusions Wolbachia w as found infecting Anopheles and other important disease vectors such as Mansonia . Since Wolbachia can affect its host by reducing the life span and provide resistance to pathogen infection, several studies have suggested it as a potential innovative tool for vector/vector-borne disease control. Therefore, it is important to carry out further studies on natural Wolbachia infection in vector mosquitoes’ populations as well as their long-term effects in new hosts and pathogen suppression.

Background Arboviruses are a group of viruses transmitted to vertebrate hosts by certain blood-feeding arthropods. Among urban vectors of arboviruses, mosquitoes of the genus Aedes are the most common. However, other mosquitoes may be susceptible to infection and involved in the transmission, such as Mansonia spp. Therefore, this study aimed to investigate whether Mansonia humeralis can be infected with the Mayaro virus (MAYV). Methods These insects were collected from 2018 to 2020 in chicken coops of rural communities in Jaci Paraná in Porto Velho, Rondônia, Brazil, while performing blood-feeding on roosters. The mosquitoes were randomly grouped in pools from which the head and thorax were macerated and checked for the presence of MAYV by quantitative reverse transcription polymerase chain reaction (RT-qPCR). The positive pools were used to infect the C6/36 cell line, and on different days post-infection, the supernatant of the infected cells was subjected to viral detection by RT-qPCR. Results A total of 183 pools of female mosquitoes were tested, of which 18% were positive for MAYV; some samples from insect pools inoculated into C6/36 cells showed in vitro multiplication capacity between 3 and 7 days post-infection. Conclusions This is the first report of Ma. humeralis mosquitoes that are naturally infected by MAYV, indicating that these vectors may be potential transmitting agents of this arbovirus. Graphical Abstract

The eggs of three Amazonian species of the genus Mansonia (Diptera: Culicidae) were analyzed using morphological and morphometric characters. Eggs of Mansonia humeralisDyar & Knab, 1916 were morphologically different from those of Mansonia titillans (Walker, 1848) and Mansonia amazonensis (Theobald, 1901), which were more similar to each other according to linear and geometric morphometry. A principal component analysis generated from elliptic Fourier contour data (PC1—92.6% and PC2—2.61%) indicated that Ma. amazonensis and Ma. titillans are more similar to each other than either is to Ma. humeralis. Discriminant multivariate analysis was highly accurate with only four classification errors and a 90% accuracy rate. The results indicate that the three Amazonian species can be precisely distinguished in the egg stage and that geometric morphometry based on elliptic Fourier contours is a promising method for distinguishing eggs of species of Mansonia. An identification key based on egg morphology is provided to distinguish the four Neotropical species.

Terminalia ivorensis and Mansonnia altissima is an important tropical timber tree plant, but poor germination is an important factor militating its regeneration. Effects of pretreatments on germination of seeds of Terminalia ivorensis and Mansonia altissima were studied. Four hundered and eighty matured seeds of Terminalia ivorensis and three hundred and sixty seeds of Mansonia altissima were obtained from Forest Reserve Institute of Nigeria (FRIN), Ibadan. The seeds were divided into twenty-one equal portions of 10 seeds each. Twelve pretreatments were investigated on Terminalia ivorensis and nine pretreatments on Mansonia altissima. The seeds were sown inside plastic basket containing sterilized river sand under high humidity propagator with four replicates each. Germination counts were taken daily for eighty days. Percentage germination was computed for each treatment and the data were subjected to analysis of variance. Germination was first observed among the scarified Terminalia ivorensis seeds at 14 days after sowing (DAS) and this treatment group had the highest percentage germination of 82.5%, while seeds soaked in hot water recorded the least germination. Germination was first observed in decoated Mansonia altissima and this treatment group had the highest percentage germination of 45%, whereas the least was observed among the treatments with H­2SO4. The effect of pretreatment was highly significant (p≤0.05) on the germination of both species. It is therefore recommended that mechanical scarification of Terminalia ivorensis and decoating seed of Mansonia altissima will enhance the germination of the two species.

Mosquitoes (Diptera: Culicidae) from Porto Alegre region (Rio Grande do Sul state, Brazil) remain understudied. We therefore investigated mosquitoes occurring in 11 sites of this region, and evaluated which landscape features may explain the variation of species richness and composition of mosquito populations in different urban-natural areas of the study region. Using BG-Pro traps, we collected 4311 mosquitoes, from at least 50 species, 14 genera, and two subfamilies. Mansonia titillans (n = 598, 13.87%), Culex spp. (n = 513, 11.9%), and Mansonia wilsonii (n = 502, 11.65%) were the most abundant taxa. Aedes aegypti (n = 36, 0.84%) is potentially exploring new landscapes in the region, beyond human habitations. We identified two new descriptions for the Rio Grande do Sul state, Mansonia pessoai (n = 70, 1.62%) and Toxorhynchites theobaldi (n = 6, 0.14%). The model selection procedure identified that the percentage coverage of temporary crops and the Simpson’s diversity index at landscape level as possible variables explaining the species richness, while percentage coverage of urban and temporary crops were the best predictors of species composition. BG-Pro traps were efficient for catching several adult mosquito species including Toxorhynchites mosquitoes. Therefore, this could be an interesting sampling methodology for mosquito surveillance.Implications for insect conservationThis study expanded the knowledge about Culicidae diversity in Brazil, highlighted the importance of green urban areas for biodiversity conservation, and provided data for entomological surveillance programs. This study also contributes to the conservation of mosquito species that pose no risk to human health (e.g., Toxorhynchites), highlighting that such species have relevant ecological roles, unrelated to disease transmission.

Rift Valley fever (RVF) is a major viral zoonosis transmitted by mosquitoes. The virus is endemic in most parts of sub-Saharan Africa and can affect humans, livestock, and wild ungulates. Knowledge of the biology of vectors of Rift Valley fever virus (RVFV) is essential for the establishment of effective control measures of the disease. The objective of this study was to determine the species diversity and relative abundance of potential RVFV vectors in the North Region of Cameroon. Adult mosquitoes were trapped during the wet and dry seasons from December 2017 to January 2019 with “EVS Light” traps with CO2 baits placed at selected sites. The captured mosquitoes were identified using dichotomous keys according to standard procedures. The abundance was calculated with regard to site, zone, and collection season. A total of 27,851 mosquitoes belonging to four genera (Aedes, Anopheles, Mansonia, and Culex) and comprising 31 species were caught (including 22 secondary vectors (98.05%) and nine primary vectors (1.94%). The total number of mosquitoes varied significantly depending on the locality (p-value < 0.001). The average number of mosquitoes collected per trap night was significantly higher in irrigated areas (p-value < 0.001), compared to urban and non-irrigated areas. The study revealed the presence of potential primary and secondary vectors of RVFV with varying abundance and diversity according to locality and ecological site in the North Region of Cameroon. The results showed that the genus Mansonia with the species Ma. uniformis and Ma. africana formed the dominant taxon (52.33%), followed by the genera Culex (45.04%) and Anopheles (2.61%). The need for molecular analysis (PCR) tests for RVFV RNA research and viral isolation methods on these vectors to determine their role in the epidemiology and control of RVF cannot be overemphasized.

This study aimed to investigate indirect micropropagation of Mansonia altissima using nodal explant and confirmation of genetic stability of the plantlets in order to establish the protocol for callus induction, mass propagation, and true to type clones. Murashige and Skoog (MS) medium supplemented with 1.0, 2.0, 4.0, 8.0, and 10.0 μM IAA (indole-3-acetic acid) or 1.0, 2.0, 4.0, 8.0, and 10.0 μM IBA (indole-3-butyric acid) and 50.0 mg·L −1 l -ascorbic acid was used for callus induction. The callus was subcultured on Murashige and Skoog (MS) medium containing BAP (6-benzylaminopurine) (μM) or TDZ (thidiazuron) (μM) and KIN (kinetin) (μM). The induced shoots were cultured on different strength MS medium, activated charcoal, and indole-3-butyric acid (μM) for root induction. The plantlets were acclimatized to the environment using four different types of potting media. Polymerase chain reaction amplification of the wild and indirect micropropagated M. altissima was done using 6 inter simple sequence repeats and 15 random amplified polymorphic DNA primers. Explants cultured on MS medium containing 4.0 μM IAA and 50.0 mg·L −1 l -ascorbic acid had the highest percentage (95.00%) of callus formation, while 10.0 μM BAP and 0.5 μM KIN showed the highest number of shoots (17.67) and shoot height (2.03 cm) per callus. The highest number of roots (14.47) and root length (2.67 cm) was obtained in ¼ MS medium supplemented with 8.0 μM IBA and 1.0 g·L −1 activated charcoal. Moreover, plantlets were successfully acclimatized in the greenhouse. The PCR results showed true to type clones.

BACKGROUND: Recent data from Ghana indicates that after seven rounds of annual mass drug administration (MDA) there is still sustained transmission albeit at low levels in certain areas where Anopheles melas, An. gambiae s.s., Mansonia and Culex species are the main biting mosquitoes. Anopheles gambiae s.l. and An. funestus are the known vectors in Ghana and a recent report indicated that An. melas could transmit at low level microfilaraemia. However, because An. melas is not found everywhere there was the need to determine whether any of the other culicine species could also be playing a role in the transmission of LF. METHODS: Indoor mosquitoes collected once a month for three months using pyrethrum spray catches in six communities within the Kommenda-Edina-Eguafo-Abirem (KEEA) District, Central Region of Ghana were morphologically identified, dissected and examined for the presence of W. bancrofti. Additionally, stored mosquito samples collected during previous years in 8 communities from the Gomoa District also in the Central Region were similarly processed. The identities of all W. bancrofti parasites found were confirmed using an established PCR method. RESULTS: A total of 825 indoor resting mosquitoes comprising of 501 Anopheles species, 239 Mansonia species, 84 Culex species and 1 Aedes species were dissected and examined for the presence of W. bancrofti. Mansonia africana had infection and infectivity rates of 2.5%. and 2.1% respectively. Anopheles gambiae s.l. had an infection rate of 0.4% and a similar infectivity rate. None of the Culex sp. and Aedes sp were found with infection. From the stored mosquitoes the infection and infectivity rates for M. africana were 7.6% (N = 144) and 2.8% respectively whilst the corresponding rates for M. uniformis were 2.9% (N = 244) and 0.8%. CONCLUSIONS: This is the first report of Mansonia species as vectors of lymphatic filariasis (LF) in Ghana and in West Africa since that of 1958 in Guinea. The revelation of a hitherto unrecognised vector which is possibly more efficient in transmission than the recognised ones has a profound implication for elimination of lymphatic filariasis programmes in the sub-region.