Evaluation of insecticide resistance in Aedes aegypti populations connected by roads and rivers: the case of Tocantins state in Brazil

BACKGROUND The longstanding application of insecticides for vector control without periodic monitoring of the population response to these chemicals can directly drive the selection of resistant populations of vector mosquitoes. Tocantins is the newest state of the Brazilian Federation. Despite a historically high number of dengue cases, studies and monitoring data concerning insecticide resistance in the state are lacking. OBJECTIVES To verify the resistance status of Aedes aegypti from 10 populations distributed throughout the state connected by rivers and roads. METHODS Between 50 and 150 ovitraps were installed in house gardens within each municipality. Collection points were established based on the importance of the towns and on geographic aspects. Dose response bioassays were performed in accordance with World Health Organization guidelines. Molecular assays were conducted to detect kdr mutations, which are related to pyrethroid resistance. FINDINGS Of the 3,200 ovitrap paddles analysed, 25.8% contained eggs, with a total of 55,687 eggs collected. With the exception of Caseara, all evaluated populations were considered to be resistant to temephos. The data showed different levels of resistance to deltamethrin among the samples. Caseara and Guaraí showed the lowest RR95 values. On average, the NaVR1 kdr allele was most frequent (40.3%), followed by NaVS (38.1%), and NaVR2 (21.6%). Palmas, the capital of the state, had the highest frequency of kdr alleles (87.5%). MAIN CONCLUSIONS With the exception of Palmas, the towns with the highest indexes (ovitrap positivity, number and density of eggs), as well with high levels of resistance and kdr alleles were located along the BR-153 road, indicating that the flow of people and cargo can contribute to the dispersion of the vector and potentially resistance. This study contributes substantially to knowledge regarding the insecticide resistance profile of Tocantins mosquito populations; the data generated via the study could facilitate the judicious use of insecticides by vector control programs.

Revisão taxonômica dos Grupos Atratus e Educator do subgênero Melanoconion de Culex (Diptera, Culicidae) / Taxonomic review of the Atratus and Educator Groups of the subgenus Melanoconion of Culex (Diptera, Culicidae)

Entre os múltiplos grupos que compõem as Seções Spissipes e Melanoconion do subgênero Melanoconion de Culex, Atratus e Educator apresentam espécies que estão envolvidas na transmissão de arbovírus ao ser humano e animais em ambientes rurais e silvestres. Porém, esses grupos exibem grande dificuldade na identificação das espécies, seja devido à grande semelhança morfológica entre seus representantes ou à falta de chaves de identificação atualizadas. Diante disso, objetivou-se realizar a revisão taxonômica das espécies pertencentes aos Grupos Atratus e Educator da Seção Melanoconion de Culex (Melanoconion). Para isso, foi realizado o estudo morfológico detalhado das diversas fases de desenvolvimento dos espécimes de interesse, verificada a existência de espécies a serem nomeadas e/ou espécies válidas colocadas na sinonímia de outras. Como resultado do estudo morfológico das espécies do Grupo Atratus, foram redefinidas oito espécies. Destas, duas foram validadas, pois estavam na sinonímia de outras e seis espécies desconhecidas da ciência foram descritas e serão formalmente nomeadas. Para o Grupo Educator, oito espécies foram descritas, sendo uma removida da sinonímia e três espécies desconhecidas da ciência foram descritas e serão formalmente nomeadas. Chaves de identificação ilustradas, com caracteres usados para o reconhecimento das espécies, foram elaboradas para todas as formas de desenvolvimento das espécies de ambos os grupos. Foram construídos mapas de distribuição geográfica das espécies, foram atualizados dados bionômicos, elaboradas ilustrações e pranchas fotográficas para comparação de estruturas morfológicas externas das formas imaturas, adultos e genitália masculina

Among the multiple groups that compose the Spissipes and Melanoconion Sections of the subgenus Melanoconion of Culex, the Atratus and Educator Groups present species that are involved in the transmission of arboviruses to man and animals in rural and wild environments. However, these groups present great difficulty in identifying the species, either because of the great morphological similarity between their representatives or the lack of updated identification keys. The aim of this study was to carry out a taxonomic review of the species belonging to the Atratus and Educator Groups of the Melanoconion Section of Culex (Melanoconion). Therefore, a detailed morphological study of the several stages of development of the specimens of interest was carried out, verifying the existence of species to be named and/or valid species placed in the synonymy of others. As a result of the morphological study of the Atratus Group species, eight species were redefined. Of these, two were resurrected from the synonymy of others and six species unknown to science were described and will be formally named. For the Educator Group, eight species have been described, one being removed from the synonymy and three species unknown to science have been described and will be formally named. Illustrated identification keys, with characters used for species recognition, have been created for all forms of development of species in both Groups. Geographic distribution maps of the species were created, illustrations and photographic plates for comparison of external morphological structures of the immatures forms, adults and male genitalia were provided, and bionomic data were updated

Effectiveness of Mosquito Magnet® trap in rural areas in the southeastern tropical Atlantic Forest

Traps are widely employed for sampling and monitoring mosquito populations for surveillance, ecological and fauna studies. Considering the importance of assessing other technologies for sampling mosquitoes, we addressed the effectiveness of Mosquito Magnet® Independence (MMI) in comparison with those of the CDC trap with CO2 and Lurex3® (CDC-A) and the CDC light trap (CDC-LT). Field collections were performed in a rural area within the Atlantic Forest biome, southeastern state of São Paulo, Brazil. The MMI sampled 53.84% of the total number of mosquitoes, the CDC-A (26.43%) and CDC-LT (19.73%). Results of the Pearson chi-squared test (χ2) showed a positive association between CDC-LT and species of Culicini and Uranotaeniini tribes. Additionally, our results suggested a positive association between CDC-A and representatives of the Culicini and Aedini tribes, whereas the MMI was positively associated with the Mansoniini and Sabethini as well as with Anophelinae species. The MMI sampled a greater proportion (78.27%) of individuals of Anopheles than either the CDC-LT (0.82%) or the CDC-A traps (20.91%). Results of the present study showed that MMI performed better than CDC-LT or CDC-A in sampling mosquitoes in large numbers, medically important species and assessing diversity parameters in rural southeastern Atlantic Forest.

Comparison of automatic traps to capture mosquitoes (Diptera: Culicidae) in rural areas in the tropical Atlantic rainforest

In several countries, surveillance of insect vectors is accomplished with automatic traps. This study addressed the performance of Mosquito Magnet® Independence (MMI) in comparison with those of CDC with CO2 and lactic acid (CDC-A) and CDC light trap (CDC-LT). The collection sites were in a rural region located in a fragment of secondary tropical Atlantic rainforest, southeastern Brazil. Limatus durhami and Limatus flavisetosus were the dominant species in the MMI, whereas Ochlerotatus scapularis was most abundant in CDC-A. Culex ribeirensis and Culex sacchettae were dominant species in the CDC-LT. Comparisons among traps were based on diversity indices. Results from the diversity analyses showed that the MMI captured a higher abundance of mosquitoes and that the species richness estimated with it was higher than with CDC-LT. Contrasting, difference between MMI and CDC-A was not statistically significant. Consequently, the latter trap seems to be both an alternative for the MMI and complementary to it for ecological studies and entomological surveillance.

Avaliação em campo de três armadilhas automáticas para capturar mosquitos (Diptera: Culicidae) em área agrícola de Pariquera-Açu, São Paulo, Brasil / Field evaluation on three automatic traps to capture mosquitoes (Diptera: Culicidae) in agricultural area of Pariquera-Açu, São Paulo, Brazil

Introdução: As diversas armadilhas apresentam rendimento diferenciado na captura, havendo a necessidade de buscar instrumentos que amostrem porções representativas das populações de mosquitos. Levanta-se a hipótese de que as armadilhas Mosquito Magnet Independence e CDC com CO2+Lurex3 sejam mais eficazes na captura de culicídeos do que a armadilha CDC luminosa. Objetivos: Avaliar a eficácia das armadilhas Mosquito Magnet Independence e CDC+CO2+Lurex3, em relação à CDC-luminosa, para a captura de culicídeos adultos em área agrícola na Fazenda Experimental em Pariquera-Açu, Vale do Ribeira, São Paulo, Brasil. Material e Métodos: Capturas mensais, das 15h00 às 21h00, por meio do delineamento em quadrado latino 3X3, no período de dezembro/2010 a novembro/2011. Perfis de diversidade de Rényi e índices de riqueza, dominância, diversidade, equabilidade e similaridade foram estimados para cada armadilha para compará-las. Resultados: Capturou-se 6.055 de 70 espécies e 12 gêneros. A CDC-luminosa amostrou 990 indivíduos de 42 espécies e 10 gêneros,a CDC+CO2+lurex31.419 indivíduos em 41 espécies e 10 gêneros e a Mosquito Magnet 3151 indivíduos de 46 espécies e 11 gêneros. A riqueza, pelo índice de Margalef e Perfil de Rényi, não apresentou diferença estatística para nenhuma armadilha no período dez/mai. A Mosquito Magnet obteve maior rendimento na mensuração da diversidade, segundos os índices de Shannon e Simpson, observados no perfil de Rényi. A dominância, pelo índice de Berger-Parker isolado,foi maior na Mosquito Magnet do que nas demais, nos dois períodos de capturas. O perfil de Rényi não apontou diferença significante para dominância. Índice de Pielou não mostrou significância em relação à CDC-luminosa para nenhuma das armadilhas nos dois períodos avaliados. Índices de Jaccard e Sorensen apontaram maior similaridade na composição de espécies entre a Mosquito Magnet e CDC+CO2+lurex3. Conclusões: A Mosquito Magnet Independence e CDC+CO2+Lurex3 apresentaram rendiment...