Bioassays were performed in order to detect the susceptibility of Aedes aegypti to the chemical insecticides temephos and cypermethrin. The results showed that this species is susceptible to temephos and presents resistance to cypermethrin.The strategies for controlling the principal vector of dengue, Aedes aegypti, are based on the utilization of chemical and biological products, integrated with environmental management programs. In Brazil, the programs that aim to control Aedes aegypti mainly utilize chemical insecticides, among which organophosphates (OP) and pyrethroids (P) are prominent. These programs require constant monitoring.The numbers of dengue cases are rising every year, and different factors influence this increase. Resistance to chemical products may favor an increase in the mosquito populations, thereby resulting in increases in the numbers of dengue cases. 1,4 For this reason, it is important to perform periodic monitoring of the susceptibility to insecticides of the populations implicated in the transmission of this disease. 3 This study presents data on the susceptibility of a population of Aedes aegypti in the city of Curitiba, State of Paraná, for the first time. This population was submitted to two chemical insecticides: temephos (organophosphate) and cypermethrin (pyrethroid). The resistance ratio was compared with the data for the standard colony at the Centers for Disease Control and Prevention (CDC).Immature specimens were collected from different districts of Curitiba between January and April 2003.Aedes aegypti was only found in the sample from the Uberaba district, in an artificial breeding ground (automobile wreckage in a scrap metal yard). This was the only population originating from Curitiba utilized in the susceptibility tests.The lineage utilized for making the comparison was the Rockefeller CDC. The insecticides utilized in the bioassays were temephos, "Temephos Fersol 1G" (granulated, 1%), and cypermethrin, "Cynoff 400 Pm" (powder, 25%). These products were diluted in mineral water to prepare the standard solutions with the same concentration of 50 ppm of active ingredient.The process for the bioassays followed the standards of the World Health Organization (WHO). 5 The results were submitted to Probit analysis. 2 The following criteria were utilized for determining the resistance: if the mortality rate was greater than or equal to 98%, the sample was considered to susceptible; if the mortality rate was 80 to 97%, the response was checked by repeating the experiment; and if the mortality rate was less than 80%, the sample was considered to be resistant. 5 A total of 750 larvae were analyzed in relation to cypermethrin and 700 in relation to temephos, in-
RESUMO.A planície de inundação do alto rio Paraná caracteriza-se pela grande diversidade de organismos aquáticos e as larvas de Chironomidae destacam-se por sua elevada abundância. A partir da hipótese de que as variáveis abióticas influenciam a composição, densidade e dominância das larvas de Chironomidae em diferentes ambientes e períodos amostrados, este trabalho objetivou: caracterizar o rio Baía, canal secundário, lagoa não-conectada (Fechada) e lagoa conectada (Guaraná) da planície de inundação do alto rio Paraná, de acordo com os atributos da assembléia de Chironomidae e identificar possíveis gradientes de distribuição espacial e temporal das larvas, relacionando-as com algumas variáveis abióticas. As coletas foram realizadas no período de março de 2003 a dezembro de 2005, em três pontos distintos (margens e centro), com o auxílio de um pegador tipo Petersen modificado. A Análise de Correspondência Canônica mostrou que as larvas foram influenciadas principalmente pela textura granulométrica do sedimento. O canal Curutuba, pela presença de seixos, diferenciou-se das demais estações de coleta como rio Baía e as lagoas de inundação onde predominaram as partículas mais finas. Pode-se concluir que a composição granulométrica, a porcentagem de matéria orgânica presente no sedimento e a hidrodinâmica de cada ambiente foram os principais fatores que influenciaram a distribuição espacial das larvas de Chironomidae.Palavras-chave: insetos aquáticos, dominância, composição granulométrica, planície de inundação, rio Paraná.ABSTRACT. Temporal and spatial distribution of Chironomidae larvae in different environments of the Baía river complex, Mato Grosso do Sul State, Brazil. The floodplain of the upper Paraná river is characterized by the great diversity of aquatic organisms, and the larvae of Chironomidae are distinguished for their high density. Starting from the hypothesis that abiotic variables influence Chironomidae larvae composition, density and dominance in different environments and sampled periods, this study aimed to characterize the Baía river, secondary channel, floodplain lakes (connected and non-connected) of the Paraná river floodplain, according to attributes of Chironomidae assemblage, and identify possible gradients of temporal and spatial distribution of the larvae, relating them with abiotic variables. The collections were carried out from March 2003 to December 2005. Samples were collected in three points (margins and center), using a modified Petersen grab. CCA showed the larvae were influenced mainly by sediment particle size. Curutuba channel, due to the presence of pebbles, differed from other sites such as the Baía river and floodplain lakes, where fine particles predominated. It was concluded that particle size composition, percentage of organic matter and hydrodynamic of each environment were the main variables that influenced the spatial distribution of Chironomidae larvae.
Galactomannans (GMs) extracted from seeds of a native Brazilian specie designated Cassia fastuosa (cassia) and from Cyamopsis tetragonolobus (guar gum - a commercial GM) were mixed with agar, in the proportion of 3/3 g.L¹ (w/w), and used as a gelling agent in Marubakaido apple rootstock (Malus prunifolia Borkh) micropropagation. The rheological measurements of the gels showed a good interaction between both hidrocolloids. The micropropagation results on these media were compared with behaviour of standard medium containing agar only (6 g.L-1). Results from in vitro experiments indicated enhanced proliferation of apple shoots and also the occurrence of hyperhydric shoots was lower in the modified gel-medium
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