Oviposition of Aedes aegypti Linnaeus, 1762 and Aedes albopictus Skuse, 1894 (Diptera: Culicidae) under laboratory and field conditions using ovitraps associated to different control agents, Manaus, Amazonas, Brazil

ABSTRACT The aim of this study was to analyze the effectiveness of different control agents of Aedes aegypti and Aedes albopictus associated with ovitraps under laboratory and field conditions. Five treatments were used: grass infusion + Bacillus thuringiensis israelensis (gI + Bti), grass infusion + Saccharopolyspora spinosa (gI + Ss), grass infusion + Pyriproxyfen (gI + P), distilled water + Toxorhynchites haemorrhoidalis (dW + Th), and grass infusion (gI) (control). The highest mean number of eggs of both species were obtained with grass infusion in the laboratory. Among control agents, the lowest mean of A. aegypti eggs occurred with gI + Ss and the lowest mean of A. albopictus eggs occurred with dW + Th. There was no difference between treatments in A. aegypti (P = 0.4320) and A. albopictus (P = 0.7179). In the field, the highest mean number of eggs for both species were obtained with gI + Ss, and the lowest values were obtained with gI + P (P = 0.0124). The treatments can be applied to both the surveillance and the control, but ovitraps with biological larvicide Bti were more effective and safer considering the number of eggs laid and selectivity of pathogens for mosquitoes.

Effect of Bacillus sphaericus Neide on Anopheles (Diptera: Culicidae) and associated insect fauna in fish ponds in the Amazon

ABSTRACTWe analyzed the effects of Bacillus sphaericus on Anopheles larvae and on the associated insect fauna in fish farming ponds. Five breeding sites in the peri-urban area of the city of Manaus, AM, Brazil, were studied. Seven samples were collected from each breeding site and B. sphaericus was applied and reapplied after 15 days. The samples were made at 24 h before application, 24 h post-application and 5 and 15 days post-application. We determined abundance, larval reduction and larval density for Anopheles, and abundance, richness, Shannon diversity index and classified according to the functional trophic groups for associated insect fauna. A total of 904 Anopheles larvae were collected and distributed into five species. Density data and larval reduction demonstrated the rapid effect of the biolarvicide 24 h after application. A total of 4874 associated aquatic insects belonging to six orders and 23 families were collected. Regression analysis of diversity and richness indicated that the application of the biolarvicide had no influence on these indices and thus no effect on the associated insect fauna for a period of 30 days. B. sphaericus was found to be highly effective against the larvae of Anopheles, eliminating the larvae in the first days after application, with no effect on the associated insect fauna present in the fish ponds analyzed.

Controle da malária: eficácia de formulados de Bacillus sphaericus 2362 contra larvas de espécies de anopheles em criadouros artificiais - tanques de psicultura e criadouros de Olaria / Malaria control: efficacy of Bacillus sphaericus 2362 formulations against anopheles species larvae in man-made breeding sites such as fish culture ponds and brickyard puddles

Objetivo: Avaliar a eficácia e a persistência de diferentes formulações de Bacillus sphaericus 2362, em doses com o dobro do que é recomendado pels fabricantes, para controle das formas imaturas de espécies de Anopheles, vetor da malária, diante da composição da água dos criadouros artificiais. Métodos: Tanques de psicultura e lagos de olaria, localizados nos municípios de Manaus e Iranduba e contendo formas imaturas de anofelinos, foram tratados com concentrações dobradas. As doses dos larvicidas - Vectolex - 22Kg/ha, Griselesf- 200L/ha e Spherimos- 6L/ha - foram aplicadas nos seguintes criadouros: Sítio Fazendinha- 7 tanques e 1 controle (sem larvicidas); Sítio Três Irmãos- 6 tanques e 1 controle; Sítio Santa Cecília- 9 tanques e 2 controles: Olaria Cerama- 26 lagoas e 5 controles. Coletas de anofelinos para determinar os índices de larva por homem/hora (ILHH) das formas jovens (primeiro e segundo estádios) e das formas maduras (terceiro e quarto estádios) foram feitas antes da aplicação e após no segundo, sétimo, décimo quarto, vigésimo primeiro, vigésimo oitavo e trigésimo quinto dias. Resultados: Os resultados da densidade larvária nos criadouros artificiais demonstram que, nos tanques de psicultura, o número de larvas observado foi quatro vezes maior (33.729 larvas) do que nos criadouros de olaria (7.972 larvas). Na avaliação dos formulados nos tanques de psicultura de Manaus e Iranduba, observaram-se menores valores do ILHH, na leitura do segundo dia, nos criadouros onde se aplicam Vectolex e Spherimos do que nos criadouros-controle; nos tanques tratados com Griselesf, ao contrário, os valores do ILHH estavam próximos aos encontrados no controle, ultrapassando esses índices larvários nas demais observações. Os formulados Spherimos e Vectolex apresentaram padrões similares de redução próximos a 100por cento, no segundo dia de observação, tanto para as larvas jovens como para as maduras. Quando se consideram os resultados para o Griselesf...

Larvicidal activity of bacilus sphaericus 2362 against Anopheles nuneztovari, Anopheles darlingi and Anopheles braziliensis (diptera, culicidae)

Foram obtidos neste trabalho, os primeiros dados relativos a sensibilidade de anofelinos vetores da malaria na Amazonia - An. nuneztovari, An. darlingi e An. braziliensis, a B. sphaericus 2362 estirpe padrao da OMS. Inicialmente, foram realizados bioensaios para verificar a susceptibilidade dos estadios larvais. Para as duas primeiras especies, os dados evidenciaram que o terceiro estadio e o menos sensivel e que, para An. darlingi, alem deste, o segundo estadio mostrou baixa mortalidade. Na continuidade, a estirpe padrao foi testada contra as especies de Anopheles e verificou-se que An. nuneztovari foi a menos sensivel a estirpe 2362 quando comparada as outras especies...

Studies on the Bacillus sphaericus larvicidal activity against malarial vector species in Amazonia

In this work, bioassays were carried out in laboratory conditions (average temperature 26 ñ 2ºC) to test ten strains of Bacillus sphaericus, isolated from Brazilian soils third instar larvae from anopheline species recorded as malaria vectors in Amazonian - Anopheles nuneztovari and An. darlingi. With the former mosquito, three strains - S 2', S 20 and S 46 showed relative activity, in 24 and 48 hr exposure to the B. spahericus strains. With the latter only the S 20 were effective in the 48 hr reading. The studied strains that showed the most adequate response in the Amazonian region were S 2 and S 20 showing broader and more efficient results. Therefore, S2 was the most effective when the 24 and 48 hr reading were considered, because it showed the greatest relative activity values.