ABSTRACT
Aedes aegypti is a culicide that has gained relevance over the years due to its ability to transmit various viruses that cause diseases in humans that all the years cause high mortality rates in the world population. The main problem is that Ae. aegypti has managed to establish and maintain a close relationship with humans and their habitat, which is why the search for alternatives to control vector populations becomes imperative. The objective of the present work was to study the effects of two Beauveria bassiana strains on Aedes aegypti. Third instar larvae of Ae. aegypti in 250 mL plastic containers were inoculated with the GHA and NB3 strains at different concentrations (1.5 × 104, 1.5× 105, 1.5 × 106 and 1.5 × 107 conidia/mL). The NB3 strain presented highest mortality values with 63% in the highest concentration i.e., 1.5 × 107, while for the GHA strain the highest mortality value was 30.7% at the same concentration. The results showed significant difference in mortality with respect to the strain and days post treatment (P = 0.0001), but not with respect to the conidial concentration (P = 0.634). The average mortality of larvae per day for the NB3 for different concentrations ranged from 20 to 25 larvae per day, while for the GHA daily mortality ranged from 5 to 12 larvae. In post-treatment mortality, the highest mortality was recorded in the third stage larvae for the NB3, while for GHA the highest percentage mortality was observed in individuals who managed to reach the adult state. The findings of the current research depicted the noteworthy role of B. bassiana for the management of an important vector of human disease.
O Aedes aegypti é um culicida que vem ganhando relevância ao longo dos anos devido à sua capacidade de transmitir diversos vírus causadores de doenças em humanos que ao longo dos anos ocasionam altas taxas de mortalidade na população mundial. O principal problema é que Ae. aegypti tem conseguido estabelecer e manter uma relação próxima com o homem e seu habitat, por isso a busca por alternativas para o controle das populações de vetores torna-se imperativa. O objetivo do presente trabalho foi estudar os efeitos de duas cepas de Beauveria bassiana sobre Ae. aegypti. Larvas de terceiro instar de Ae. aegypti em recipientes plásticos de 250 mL foram inoculados com as cepas GHA e NB3 em diferentes concentrações (1.5 × 104, 1.5 × 105, 1.5 × 106 e 1.5 × 107 conídios/mL). A cepa NB3 apresentou os maiores valores de mortalidade com 63% na concentração mais alta, ou seja, 1.5 × 107, enquanto para a cepa GHA o maior valor de mortalidade foi 30.7% na mesma concentração. Os resultados mostraram diferença significativa na mortalidade com relação à cepa e dias pós-tratamento (P = 0.0001), mas não com relação à concentração de conídios (P = 0.634). A mortalidade média de larvas por dia para o NB3 para diferentes concentrações variou de 20 a 25 larvas por dia, enquanto para o GHA a mortalidade diária variou de 5 a 12 larvas. Na mortalidade pós-tratamento, a maior mortalidade foi registrada nas larvas de terceiro estágio para o NB3, enquanto para o GHA o maior percentual de mortalidade foi observado em indivíduos que conseguiram atingir o estado adulto. Os resultados da pesquisa atual retratam o papel notável de B. bassiana no manejo de um importante vetor de doenças humanas.
Subject(s)
Animals , Aedes , Beauveria/pathogenicity , Pest Control/methods , Arbovirus Infections/veterinaryABSTRACT
BACKGROUND In this study, we evaluated the role of free-living domestic pigeons (Columba livia) as a reservoir of arboviruses in the city of Belém, state of Pará, Brazil. We investigated the presence of antibodies against the most prevalent arboviruses. OBJECTIVES This study was aimed at evaluating some clinical and physical parameters of domestic pigeons, including the presence of antibodies to Amazon-endemic arboviruses. METHODS Eighty-five healthy pigeons were captured in Mangal das Garças Park, in Belém, and were bled. Upon capture, the birds were subjected to a clinical examination in search of alterations that could indicate the presence of arboviruses. Blood samples were converted to serum and tested using the haemagglutination inhibition (HI) technique with a panel of 19 antigens of arboviruses circulating in the Amazon. The confirmation assay for the positive reactions to the viral species tested by HI was a neutralisation test in new-born Swiss albino mice (Mus musculus) [mouse neutralisation test (MNT)]. FINDINGS A total of 10 (11.8%) serum samples tested positive for antiflavivirus antibodies by HI. All the samples positive for the HI test were subjected to MNT for detection of viruses and yielded negative results (logarithmic neutralisation index < 1.7). MAIN CONCLUSION The results represent the first serological detection of antiarbovirus antibodies in domestic pigeons as potential hosts of arboviruses in Brazil. The detection of haemagglutination-inhibiting antibodies against genus Flavivirus indicated that there was recent contact between the analysed domestic pigeons and these arboviruses. Further studies are needed to evaluate the role of free-living pigeons in the maintenance cycle and spread of arboviruses in the Amazon.
Subject(s)
Animals , Male , Female , Mice , Arbovirus Infections/diagnosis , Arbovirus Infections/veterinary , Arbovirus Infections/virology , Columbidae/virology , Bird Diseases/diagnosis , Bird Diseases/virology , Brazil , Hemagglutination Inhibition Tests , Disease VectorsABSTRACT
O presente estudo descreve os aspectos eco-epidemiológicos sobre arbovírus nos Municípios de Novo Progresso e Trairão, Estado do Pará, Brasil, na área de influência da BR 163. Anticorpos IH foram detectados para diferentes arbovírus, com reações monotípicas para os VMAY e VORO, dois importantes arbovírus associados a epidemias na Amazônia. Anticorpos IgM para o VORO e VMAY foram detectados em soros humanos, sugerindo infecção recente por esses arbovírus. Duas cepas do VDEN-3 foram isoladas de pacientes febris residentes em Novo Progresso e identificadas como genótipo III. Em termos gerais, os dados obtidos sugerem uma área propícia para a circulação e manutenção de arbovírus e uma população pouco imunizada. Portanto, é importante um monitoramento dinâmico das populações locais e de imigrantes e de animais silvestres quanto à presença de anticorpos e isolamentos de arbovírus, o que permitirá um efetivo controle das infecções por esses agentes virais em residentes da área da rodovia dentro do território paraense.
The current study describes the eco-epidemiological aspects of arbovirus diseases in the municipalities (counties) of Novo Progresso and Trairão, Para State, Brazil, in the area affected by highway BR-163. Hemagglutination inhibition (HI) antibodies to different arboviruses were detected, with monotypic reactions to MAYV and OROV, two important arboviruses associated with epidemics in the Amazon. IgM antibodies to OROV and MAYV were found in human sera, suggesting recent infections by these viruses. Two DENV-3 strains were isolated from febrile patients in Novo Progresso and identified as genotype III strains. In general, the data suggest that the area displays ideal conditions for maintenance and circulation of arboviruses, plus a population with low immunization levels. Dynamic surveillance of local immigrants and wild animals is thus important, focusing on antibody prevalence and isolation of arboviruses, thereby allowing effective control of infections by these viral agents in the resident population along highway BR-163 in Pará State.