Larval habitats, species composition and distribution of malaria vectors in regions with autochthonous and imported malaria in Roraima state, Brazil

Background Malaria control requires local action. Assessing the vector diversity and abundance provides information on the local malariogenic potential or risk of transmission. This study aimed to determine the Anopheles species composition, habitats, seasonal occurrence, and distribution in areas with autochthonous and imported malaria cases in Roraima State. Methods A longitudinal study was conducted from January 2017 to October 2018, sampling larvae and adult mosquitoes in three municipalities of Roraima State: Boa Vista, Pacaraima and São João da Baliza. These areas have different risks of malaria importation. Four to six mosquito larval habitats were selected for larval sampling at each municipality, along with two additional sites for adult mosquito collection. All larval habitats were surveyed every two months using a standardized larval sampling methodology and MosqTent for adult mosquitoes. Results A total of 544 Anopheles larvae and 1488 adult mosquitoes were collected from the three municipalities studied. Although the species abundance differed between municipalities, the larvae of Anopheles albitarsis s.l., Anopheles nuneztovari s.l. and Anopheles triannulatus s.l. were collected from all larval habitats studied while Anopheles darlingi were collected only from Boa Vista and São João da Baliza. Adults of 11 species of the genus Anopheles were collected, and the predominant species in Boa Vista was An. albitarsis (88.2%) followed by An. darlingi (6.9%), while in São João da Baliza, An. darlingi (85.6%) was the most predominant species followed by An. albitarsis s.l. (9.2%). In contrast, the most abundant species in Pacaraima was Anopheles braziliensis (62%), followed by Anopheles peryassui (18%). Overall, the majority of anophelines exhibited greater extradomicile than peridomicile-biting preference. Anopheles darlingi was the only species found indoors. Variability in biting times was observed among species and municipalities. Conclusion This study revealed the composition of anopheline species and habitats in Boa Vista, Pacaraima and São João da Baliza. The species sampled differed in their behaviour with only An. darlingi being found indoors. Anopheles darlingi appeared to be the most important vector in São João da Baliza, an area of autochthonous malaria, and An. albitarsis s.l. and An. braziliensis in areas of low transmission, although there were increasing reports of imported malaria. Understanding the diversity of vector species and their ecology is essential for designing effective vector control strategies for these municipalities.

Anopheline species (Diptera: Culicidae) from the Maracá Ecological Station, Roraima State, Brazil

Anopheline species were sampled in different ecotones at Maracá Ecological Station and in Cantá municipality, both in Roraima State, Brazil, in June 2016. Nine species were recorded. Six species belong to the subgenus Nyssorhynchus and three species to the subgenus Anopheles. The most abundant species collected were Anopheles triannulatus s.l., Anopheles nuneztovari s.l. and Anopheles oswaldoi species B. The remaining species had frequencies lower than 10%. While A. triannulatus s.l. was the most frequent and the most widely distributed species in the studied area, Anopheles darlingi Root, the main malaria vector in the Brazilian Amazon region, was captured in two different ecotones and in low frequency. Our findings suggest that the risk of malaria outbreaks at Maracá Ecological Station may be low. This study also describes the first record of Anopheles costai Fonseca & Ramos in Maracá Ecological Station, Roraima State, increasing the distribution range of this taxon.

New Distribution Records of Anopheles darlingi in Quintana Roo, Southeastern Mexico

ABSTRACT Anopheles darlingi is considered the main vector of malaria in the Neotropical region, so knowledge of its distribution in the Americas is highly relevant for the design of strategies for prevention and control of the illness. In Mexico, An. darlingi was recorded for the first time in 1943, and currently its distribution covers the states of Campeche, Chiapas, Quintana Roo, and Tabasco. In this study, new distribution data and observations of the abundance of An. darlingi in 14 localities of Quintana Roo, southeastern Mexico, are presented.

Ecological characterization of mosquitoes (Diptera: Culicidae) in areas of the Mato Grosso Pantanal, Mato Grosso State, Brazil

Bimonthly diurnal and nocturnal captures were conducted in four different sampling sites of the Mato Grosso Pantanal region over 24 consecutive months between March 2009 and January 2011. The goal of performing these collections was to elucidate aspects of the biology and ecology of mosquitoes in this region since little to nothing is known about these aspects for many species. A total of 17,532 specimens were captured, comprising two subfamilies, nine genera, and 44 species. The main species of culicids found in the Mato Grosso Pantanal had strong ecological compatibility with well-preserved environments and with some of the specific habitats found in at least one of the four selected collection sampling sites. Anopheles darlingi, An. albitarsis, and An. triannulatus are well-suited to environments with large water bodies and greater anthropic activity. Culex nigripalpus and Cx. quinquefasciatus prefer environments with bush fragments and pronounced human action and movement. Culex declarator and Psorophora albigenu, the most eclectic, prefer wild areas and with some anthropic activity. Mansonia titillans is associated with environments offering a wide variety of natural breeding areas that enable its development, in particular natural swamp areas covered with macrophytes, which is one of the natural components of the Pantanal biome. The effect of the flooding season on the population density of anophelines is especially advantageous, with an explosion in the number of individuals in periods of widespread flooding. The region’s environmental dynamics are regulated by flooding cycles with alternating periods of flooding and drought, which are the main factors governing the ecology of the local fauna and flora. Flooding periods contribute to raising culicid species’ richness and diversity, while the droughts result in a more even distribution of specimens within species. The flooding season of the Pantanal occurs between November and May and coincides with the greatest abundance of culicid species. During this period, the human population of the region has greater contact with mosquito vectors carrying pathogens, including arboviruses, which previous studies have confirmed via seropositivity in the region’s equines and birds.

Standardization of a Polymerase Chain Reaction Protocol for Detecting Antimicrobial Peptides in Anopheles Darlingi (Diptera: Culicidae) Mosquitoes from the Brazilian Amazon

Background: Antimicrobial peptides (AMPs) are proteins of the innate immune system that can limit infections of the malaria-carrying parasite Plasmodium, which develops inside anopheline mosquitoes, the human malaria vectors. Despite this, studies on Brazilian Amazon species of anopheline mosquitoes are still needed. The aim of the study is to develop a standard molecular polymerase chain reaction (PCR) technique to detect the AMPs cecropin A (CecA) and defensin from Anopheles darlingi to support studies involving their detection and amplification and better understanding of the roles of these peptides in the Anopheles-Plasmodium interaction. Methods: The collection of anopheline mosquitoes was carried out in three municipalities in the Brazilian Amazon: Altamira and Peixe-Boi, in the state of Pará, and Cruzeiro do Sul, in the state of Acre. The primers were built based on the sequences available in GenBank, and PCR followed standard protocols with different annealing temperatures tested. The PCR products were purified and then sequenced by the dideoxy chain termination method. Results: CecA and defensin amplification were standardized with annealing temperatures of 59ºC and 55ºC, respectively. The amplified products and sequencing demonstrated the good quality of both primer sets. Conclusions: For the first time, a standardized molecular technique for detecting AMPs was described in An. darlingi, a mosquito species from the Brazilian Amazon, supporting future studies aiming to understand the interactions of this species and the action of these peptides during infection and providing important molecular markers for the control of human malaria.