Assessment of insecticide resistance of Aedes aegypti (Diptera: Culicidae) populations to insect growth regulator pyriproxyfen, in the northeast region of Brazil.

Vector control has been an essential strategy in Brazil to manage vector-borne diseases, and the use of insecticides plays an important role in this effort. Pyriproxyfen (PPF) has become a common insect growth regulator used to control juvenile stages of mosquitoes by disturbing their growth and development. This study assesses the susceptibility and resistance status of Brazilian Ae. aegypti populations that previously showed low resistance levels to PPF. Eggs of Ae. aegypti were collected from six cities located in the northeast states of Ceará (Quixadá, Icó, and Juazeiro do Norte), and Bahia (Itabuna, Brumado, and Serrinha). We used the Ae. aegypti Rockefeller strain as an experimental control and a strain known to be susceptible to insecticides. Inhibition of emergence rates by 50% of Ae. aegypti populations varied from 0.0098-0.046 µg/L. Mosquitoes from Icó, Serrinha, and Brumado showed low resistance levels [resistance ratio (RR50) = 2.33, 4.52, and 4.83, respectively], whereas moderate levels of resistance were detected in populations from Juazeiro do Norte (RR50=5.83) and Itabuna (RR50=7.88). Aedes aegypti collected from the Quixadá population showed a high resistance level to pyriproxyfen (RR50=11). The evolution of resistance in Brazilian Ae. aegypti populations to PPF can compromise vector control efforts. Continuous monitoring of insecticide resistance in Ae. aegypti is essential for making timely management decisions for effective vector control and management.

Reemergence of Yellow Fever in Brazil: The Role of Distinct Landscape Fragmentation Thresholds.

Yellow Fever Virus (YFV) reemergence in Brazil was followed by human suffering and the loss of biodiversity of neotropical simians on the Atlantic coast. The underlying mechanisms were investigated with special focus on distinct landscape fragmentation thresholds in the affected municipalities. An ecological study in epidemiology is employed to assess the statistical relationship between events of YFV and forest fragmentation in municipal landscapes. Negative binomial regression model showed that highly fragmented forest cover was associated with an 85% increase of events of YFV in humans and simians (RR = 1.85, CI 95% = 1.24-2.75, p=0.003) adjusted by vaccine coverage, population size, and municipality area. Intermediate levels of forest cover combined with higher levels of forest edge densities contribute to the YFV dispersion and the exponential growth of YF cases. Strategies for forest conservation are necessary for the control and prevention of YF and other zoonotic diseases that can spillover from the fragmented forest remains to populated cities of the Brazilian Atlantic coast.

Measuring mosquito control: adult-mosquito catches vs egg-trap data as endpoints of a cluster-randomized controlled trial of mosquito-disseminated pyriproxyfen.

BACKGROUND: Aedes aegypti and Culex quinquefasciatus are the main urban vectors of arthropod-borne viruses causing human disease, including dengue, Zika, or West Nile. Although key to disease prevention, urban-mosquito control has met only limited success. Alternative vector-control tactics are therefore being developed and tested, often using entomological endpoints to measure impact. Here, we test one promising alternative and assess how three such endpoints perform at measuring its effects. METHODS: We conducted a 16-month, two-arm, cluster-randomized controlled trial (CRCT) of mosquito-disseminated pyriproxyfen (MD-PPF) in central-western Brazil. We used three entomological endpoints: adult-mosquito density as directly measured by active aspiration of adult mosquitoes, and egg-trap-based indices of female Aedes presence (proportion of positive egg-traps) and possibly abundance (number of eggs per egg-trap). Using generalized linear mixed models, we estimated MD-PPF effects on these endpoints while accounting for the non-independence of repeated observations and for intervention-unrelated sources of spatial-temporal variation. RESULTS: On average, MD-PPF reduced adult-mosquito density by 66.3% (95% confidence interval, 95% CI: 47.3-78.4%); Cx. quinquefasciatus density fell by 55.5% (95% CI: 21.1-74.8%), and Ae. aegypti density by 60.0% (95% CI: 28.7-77.5%). In contrast, MD-PPF had no measurable effect on either Aedes egg counts or egg-trap positivity, both of which decreased somewhat in the intervention cluster but also in the control cluster. Egg-trap data, therefore, failed to reflect the 60.0% mean reduction of adult Aedes density associated with MD-PPF deployment. CONCLUSIONS: Our results suggest that the widely used egg-trap-based monitoring may poorly measure the impact of Aedes control; even if more costly, direct monitoring of the adult mosquito population is likely to provide a much more realistic and informative picture of intervention effects. In our CRCT, MD-PPF reduced adult-mosquito density by 66.3% in a medium-sized, spatially non-isolated, tropical urban neighborhood. Broader-scale trials will be necessary to measure MD-PPF impact on arboviral-disease transmission.

Quantification through TLC-densitometric analysis, repellency and anticholinesterase activity of the homemade extract of Indian cloves.

The rise of the mosquitoes-transmitted diseases, like dengue, zika and chikungunya in Brazil in the last years has increased concerns on protection against mosquitoes bites. However, the prohibitive prices of the commercially available repellents for the majority of the Brazilian population has provoked a search for cheaper solutions, like the use of the homemade ethanolic extract of Indian clove (Syzygium aromaticum L.) as repellent, which has been reported as quite efficient by the local press. In order to verify this, we performed here the quantification of the main components of this extract through high-performance thin-layer chromatography (HPTLC)-densitometry and evaluated its efficiency as a repellent and its acetylcholinesterase (AChE) inhibition capacity. Our results have proved HPTLC-densitometry as an efficient and appropriate method for this quantification and confirmed the repellency activity, as well as its capacity of AChE inhibition.

Comparative descriptions of eggs from three species of Rhodnius (Hemiptera: Reduviidae: Triatominae).

The authors describe and compare the morphological and ultrastructural characteristics of eggs from the three most recent described species of the genus Rhodnius Stål, 1859, which have not previously been studied. These species are Rhodnius colombiensis (Mejia, Galvão & Jurberg 1999), Rhodnius milesi (Carcavallo, Rocha, Galvão & Jurberg 2001) and Rhodnius stali (Lent, Jurberg & Galvão 1993). The results revealed that there are similarities in the exochorial architecture of optical microscopy and scanning electron microscopy; these include the predominance of hexagonal cells that are common to all Rhodnius species and variable degrees of lateral flattening, which is common not only to species of this genus, but also to the Rhodniini tribe. Differences in overall colour, the presence of a collar in R. milesi, a longitudinal bevel in R. stali and the precise length of R. colombiensis can be useful distinguishing features. As a result of this study, the key for egg identification proposed by Barata in 1981 can be updated.

Comparative descriptions of eggs from three species of Rhodnius (Hemiptera: Reduviidae: Triatominae)

The authors describe and compare the morphological and ultrastructural characteristics of eggs from the three most recent described species of the genus Rhodnius Stål, 1859, which have not previously been studied. These species are Rhodnius colombiensis (Mejia, Galvão & Jurberg 1999), Rhodnius milesi (Carcavallo, Rocha, Galvão & Jurberg 2001) and Rhodnius stali (Lent, Jurberg & Galvão 1993). The results revealed that there are similarities in the exochorial architecture of optical microscopy and scanning electron microscopy; these include the predominance of hexagonal cells that are common to all Rhodnius species and variable degrees of lateral flattening, which is common not only to species of this genus, but also to the Rhodniini tribe. Differences in overall colour, the presence of a collar in R. milesi, a longitudinal bevel in R. stali and the precise length of R. colombiensis can be useful distinguishing features. As a result of this study, the key for egg identification proposed by Barata in 1981 can be updated.

Oral transmission of Chagas disease by consumption of açaí palm fruit, Brazil.

In 2006, a total of 178 cases of acute Chagas disease were reported from the Amazonian state of Pará, Brazil. Eleven occurred in Barcarena and were confirmed by visualization of parasites on blood smears. Using cohort and case-control studies, we implicated oral transmission by consumption of açaí palm fruit.

[Occurrence of Panstrongylus guentheri Berg (Hemiptera: Reduviidae) in Mato Grosso do Sul State, Brazil]. / Ocorrência de Panstrongylus guentheri Berg (Hemiptera: Reduviidae) no Mato Grosso do Sul.

The first occurrence of Panstrongylus guentheri Berg in Brazil is presented. This species had been reported only in the territories of Argentina, Paraguay, Bolivia and Uruguay. We have extended the geographic distribution of this Triatominae, with two specimens captured in Bodoquena and Itaporã cities, both in Mato Grosso do Sul State, Brazil. These specimens were found in the intradomestic environment.

Ocorrência de Panstrongylus guentheri Berg (Hemiptera: Reduviidae) no Mato Grosso do Sul / Occurrence of Panstrongylus guentheri Berg (Hemiptera: Reduviidae) in Mato Grosso do Sul State, Brazil

Relata-se a primeira ocorrência de Panstrongylus guentheri Berg no Brasil. Essa espécie, até então, havia sido observada somente na Argentina, Paraguai, Bolívia e Uruguai. Desta feita, amplia-se a distribuição geográfica desse Triatominae por meio de dois exemplares capturados nos municípios de Bodoquena e Itaporã, ambos no Mato Grosso do Sul. Esses exemplares estavam em ambiente intradomiciliar.

The first occurrence of Panstrongylus guentheri Berg in Brazil is presented. This species had been reported only in the territories of Argentina, Paraguay, Bolivia and Uruguay. We have extended the geographic distribution of this Triatominae, with two specimens captured in Bodoquena and Itaporã cities, both in Mato Grosso do Sul State, Brazil. These specimens were found in the intradomestic environment.

[Morphological and histological study of eggs of six species of the Triatoma genus (Hemiptera: Reduviidae)]. / Estudo morfológico e histológico dos ovos de seis espécies do gênero Triatoma (Hemiptera: Reduviidae).

The objective of this study was to analyze the morphological and histological characteristics of eggs from six triatomine species in order to obtain a generic and specific characterization of this group of Trypanosoma cruzi vectors and better understand their phylogenetic and taxonomic aspects. The eggs of the respective species came from the collection of the Laboratório de Triatomíneos e Culicídeos da Faculdade de Saúde Pública/USP, from the Insetário do Serviço Especial de Saúde de Araraquara - SESA and from the Triatomine insectary of the Laboratório Nacional e Internacional de Referência em Taxonomia de Triatomíneos (FIOCRUZ), in Rio de Janeiro. Morphological studies were done with optical microscopy and scanning electron microscopy. Histological analyses used only optical microscopy. All of the species analyzed showed a predominance of hexagonal cells. The exchorion of Triatoma breyeri Del Ponte, T. costalimai Verano Galvão, and T. tibiamaculata (Pinto) consists of unornamented cells, overlapping or slightly separated, with a smooth, padded appearance. Meanwhile, in T. matogrossensis Leite Barbosa, T. sherlocki Papa, Juberg, Carcavallo, Cerqueira Barata, and T. williami Galvão, Souza Lima, the exchorion cells are ornamented on their entire surface with perforations and fissures. Egg histology showed undulations, pores, and orifices. The study helps to expand the generic and specific knowledge of the Triatominae subfamily. The characteristics identified in the exchorion of the eggshells can help separate close species. These new parameters will back the elaboration of future dichotomous keys, help to determine each vector species role and expand knowledge of the various species.

Estudo morfológico e histológico dos ovos de seis espécies do gênero Triatoma (Hemiptera: Reduviidae) / Morphological and histological study of eggs of six species of the Triatoma genus (Hemiptera: Reduviidae)

O objetivo deste trabalho foi analisar as características morfológicas e histológicas dos ovos de seis espécies de triatomíneos, buscando a caracterização específica e genérica desses grupo de vetores do Trypanosoma cruzi e a melhor compreensão seus aspectos filogenéticos e taxonômicos. Os ovos das espécies estudadas foram obtidos no acervo do Laboratório de Triatomíneos e Culicídeos da Faculdade de Saúde Pública/USP, do Insetário do Serviço Especial de Saúde de Araraquara - SESA e do insetário de triatomíneos do Laboratório Nacional e Internacional de Referência em Taxonomia de Triatomíneos da FIOCRUZ, RJ. Estudos morfológicos foram realizados por meio de microscopia óptica e microscopia eletrônica de varredura. Nos estudos histológicos, utilizou-se microscopia óptica. Todas as espécies analisadas apresentaram predominância de células hexagonais. O exocório de Triatoma breyeri Del Ponte, T. costalimai Verano & Galvão e T. tibiamaculata (Pinto) é constituído por células sem ornamentações, justapostas ou levemente separadas, de aspecto liso e acolchoado. Por outro lado, em T. matogrossensis Leite & Barbosa, T. sherlocki Papa, Juberg, Carcavallo, Cerqueira & Barata e T. williami Galvão, Souza & Lima, as células do exocório apresentam ornamentações, tais como, perfurações e fraturas distribuídas em toda a superfície. Na histologia dos ovos observou-se a presença de ondulações, poros e orifícios. O estudo contribui para a ampliação do reconhecimento genérico e específico da subfamília Triatominae. As características identificadas no exocório das cascas dos ovos podem auxiliar na correta determinação de espécies próximas. Esses novos parâmetros poderão subsidiar a elaboração de futuras chaves dicotômicas e auxiliar na determinação do papel de cada espécie vetora.

The objective of this study was to analyze the morphological and histological characteristics of eggs from six triatomine species in order to obtain a generic and specific characterization of this group of Trypanosoma cruzi vectors and better understand their phylogenetic and taxonomic aspects. The eggs of the respective species came from the collection of the Laboratório de Triatomíneos e Culicídeos da Faculdade de Saúde Pública/USP, from the Insetário do Serviço Especial de Saúde de Araraquara - SESA and from the Triatomine insectary of the Laboratório Nacional e Internacional de Referência em Taxonomia de Triatomíneos (FIOCRUZ), in Rio de Janeiro. Morphological studies were done with optical microscopy and scanning electron microscopy. Histological analyses used only optical microscopy. All of the species analyzed showed a predominance of hexagonal cells. The exchorion of Triatoma breyeri Del Ponte, T. costalimai Verano & Galvão, and T. tibiamaculata (Pinto) consists of unornamented cells, overlapping or slightly separated, with a smooth, padded appearance. Meanwhile, in T. matogrossensis Leite & Barbosa, T. sherlocki Papa, Juberg, Carcavallo, Cerqueira & Barata, and T. williami Galvão, Souza & Lima, the exchorion cells are ornamented on their entire surface with perforations and fissures. Egg histology showed undulations, pores, and orifices. The study helps to expand the generic and specific knowledge of the Triatominae subfamily. The characteristics identified in the exchorion of the eggshells can help separate close species. These new parameters will back the elaboration of future dichotomous keys, help to determine each vector species’ role and expand knowledge of the various species.