Regionality in vector control: effect of fluctuating temperature in the susceptibility of Aedes aegypti (Diptera: Culicidae) larvae to Pyriproxyfen.

Using Pyriproxyfen in controlling Aedes aegypti shows great potential considering its high competence in low dosages. As an endocrine disruptor, temperature can interfere with its efficiency, related to a decrease in larval emergence inhibition in hotter environments. However, previous studies have been performed at constant temperatures in the laboratory, which may not precisely reflect the environmental conditions in the field. The aim of this study was to assess the effect of the fluctuating temperatures in Pyriproxyfen efficiency on controlling Aedes aegypti larvae. We selected maximum and minimum temperatures from the Brazilian Meteorological Institute database from September to April for cities grouped by five regions. Five fluctuating temperatures (17-26; 20-28.5; 23-32.5; 23-30.5; 19.5-31 °C) were applied to bioassays assessing Pyriproxyfen efficiency in preventing adult emergence in Aedes aegypti larvae in five concentrations. In the lowest temperatures, the most diluted Pyriproxyfen treatment (0.0025 mg/L) was efficient in preventing the emergence of almost thrice the larvae than in the hottest temperatures (61% and 21%, respectively, p value = 0.00015). The concentration that inhibits the emergence of 50% of the population was lower than that preconized by the World Health Organization (0.01 mg/L) in all treatments, except for the hottest temperatures, for which we estimated 0.010 mg/L. We concluded that fluctuating temperatures in laboratory bioassays can provide a more realistic result to integrate the strategies in vector surveillance. For a country with continental proportions such as Brazil, considering regionalities is crucial to the rational use of insecticides.

One does not simply apply larvicides: Aedes aegypti from Araraquara (Brazil) has reduced susceptibility to pyriproxyfen.

Using larvicides is an essential method in the strategy to control the Aedes aegypti (Diptera: Culicidae) mosquito in Brazil. However, over the years this practice can select resistant strains, decreasing the efficiency of the larvicide in vector control. We compared two Aedes aegypti populations to verify mosquito resistance to pyriproxyfen larvicide: a population from Araraquara and a susceptible Rockefeller strain. We tested four concentrations of pyriproxyfen (0.005, 0.01, 0.02, and 0.04 mg/L) and observed that the Araraquara strain showed a significant reduction in mortality when compared to the Rockefeller strain, except in the highest concentration tested. We also found a moderate resistance for the Araraquara larvae, which may be related to Araraquara temperatures due to be optimum for Ae. aegypti most part of the epidemic periods. Survivor mosquitoes of pyriproxyfen exposure showed reduced wing centroid sizes, which is related to the mosquitoes' vectorial capacity: frequency of blood meals, chances of hematophagy, and virus dissemination ability. Our results provide the current susceptibility status of an Araraquara Ae. aegypti population and can assist in promoting information to epidemiologic surveillance agencies.

Pristina longiseta reproduction test: chronic exposure to environmental contaminants.

Aquatic worms are considered a suitable group to evaluate the effects of contaminants on the environment, although one of the main challenges is to use the species of local occurrence. Recently, Pristina longiseta was suggested to be used in acute bioassays. In this context, this study aimed to establish a chronic exposure for ecotoxicological bioassays using the cosmopolitan species of occurrence in Brazilian freshwater P. longiseta. Firstly, we tested three exposure times (4, 7, and 10 days) under the presence or absence of aeration for reproduction outputs. After determining the best configuration (7 days without aeration), we assessed the effects of the chronic exposures using the standardized reference substance potassium chloride (KCl), the antibiotic sulfamethoxazole (SMX), the flame retardant tetrabromobisphenol A (TBBPA), and the sugarcane vinasse. Our results showed suitability for applying the chronic exposure using P. longiseta and indicated the sensitivity of the offspring to KCl (EC50-7d = 0.51 g/L). Sulfamethoxazole and TBBPA caused a significant decrease in the offspring of P. longiseta (EC50-7d = 59.9 µg/L and < 62.5 µg/L, respectively). Sugarcane vinasse showed high toxicity for the species, and 4.26% of vinasse was calculated as EC50-7d. Therefore, the described protocol was successfully applied as an ecotoxicological bioassay to evaluate the effects of environmental contaminants on the reproduction rate of the freshwater worm P. longiseta.

Household slow sand filter efficiency with schmutzdecke evaluation by microsensors.

Slow sand filtration is a common technology providing potable water in rural households across Latin America, Asia and Africa. Two PVC household slow sand filters (HSSF) were operated in continuous (C-HSSF) and intermittent (I-HSSF) flow modes for eight consecutive months. A non-woven blanket was installed on the fine sand top to facilitate cleaning with scheduled maintenance undertaken every 30 days. The efficiency of each HSSF was evaluated via physico-chemical indicators (reduction of turbidity and colour) with biological performance assessed via total coliform and E. coli enumeration post treatment. There were no statistically significant differences between the continuous flow and intermittent flow models for physical-chemical and total coliform reduction parameters. However, when evaluating E. coli, C-HSSF performed better (p = 0.02). The non-woven blanket was subjected to weekly analysis using a Clark-type amperometric microsensor (diameter < 20 µm), which measured dissolved oxygen (DO) concentration in the adherent biofilm. DO microprofiles illustrated a variation in biofilm growth, which were associated with a progressive increase in the HSSF efficiency. The maximum DO depletion value measured during several months of operation showed no significant difference between I-HSSF and C-HSSF (p = 0.98). The microsensor measurements provided unprecedented results in real time. These results can help to understand the efficiency of the filter in relation to the biofilm growth, the dissolved oxygen depletion and turbidity removal.

Chironomus sancticaroli generation test applied to chemical contaminants and freshwater sediment samples.

The use of ecotoxicological bioassays has been increasing due to the importance of understanding the effects of substances on biota and to help environmental agencies determine water and sediment qualities. The use of Chironomus sp. in laboratory bioassays is extensive, but there is still a lack of studies regarding the application of extended ecotoxicological tests, which evaluate different population generation responses and show a detailed impact on their development. The present study investigated the response of Chironomus sancticaroli, a Brazilian endemic insect, to 17α-ethinylestradiol hormone, caffeine anhydrous, LAS (linear alkylbenzene sulfonate), and environmental samples (sediments) in relation to wing length, fecundity, and larval length over three generations. Statistically, differences for all contaminants between P (parental), F1, and F2 generations (p ≤ 0.05) were observed, indicating that in the environment, the organism may be negatively affected when exposed to contaminants in successive generations. Different ecological responses were also noted in comparison to classic acute (96h) and chronic (10 days) ecotoxicological tests using Chironomus sancticaroli. Our results highlight that the generation test can present more detailed results regarding the effects of stressors on the organism's life cycle than do the classic bioassays.

Application of Dispersive Liquid-Liquid Microextraction Followed by High-Performance Liquid Chromatography/Tandem Mass Spectrometry Analysis to Determine Tetrabromobisphenol A in Complex Matrices.

An accurate and sensitive ultrasound-dispersive liquid-liquid microextraction technique followed by high-performance liquid chromatography separation coupled with electrospray ionization tandem mass spectrometry detection method to determine the presence of tetrabromobisphenol A (TBBPA) in complex environmental matrices is proposed. The miniaturized procedure was used to extract and quantify the analyte in domestic sewage, anaerobic sludge, and the aquatic test organism species Daphnia magna and Chironomus sancticaroli, which are standardized organisms for ecotoxicity bioassays. Limits of detection of 2 ng L-1 (domestic sewage), 2 ng g-1 (anaerobic sludge), 0.25 ng g-1 (D. magna), and 5 ng g-1 (C. tentans) were obtained. The presence of TBBPA was determined in domestic sewage and anaerobic sludge from an anaerobic batch bioreactor at a concentration of 0.2 ± 0.03 µg L-1 and 507 ± 79 ng g-1 , respectively. In D. magna and C. sancticaroli exposed to TBBPA in an acute toxicity bioassay, the micropollutant accumulated at 3.74 and 8.87 µg g-1 , respectively. The proposed method is a simple and cost-effective tool to determine TBBPA environmental occurrence and biomagnification potential compared with conventional extraction methods. To the best of our knowledge, this is the first liquid-liquid miniaturized extraction method to be applied to D. magna and C. sancticaroli. Environ Toxicol Chem 2020;39:2147-2157. © 2020 SETAC.

Metal evaluation and ecotoxicological bioassays using Chironomus xanthus in sediments of triângulo mineiro watercourses / Avaliação de metais e bioensaios ecotoxicológicos utilizando Chironomus xanthus em sedimentos de cursos de água do triângulo mineiro

This study aimed to evaluate metal contamination in sediments of the Triângulo Mineiro watercourses and also analyze the toxicity of the sediments using Chironomus xanthus larvae, as test organisms. We collected sediments from three streams (P1, P2 and P3) and collected sediments in three points of the Uberabinha River (P4, P5 and P6). We analyzed Cu, Cr, Mn, Mg and Zn, and also performed acute and chronic toxicity tests. Acute tests were categorized into toxic (death > 50%), toxicity signs (10 < mortality < 50%) and non-toxic (mortality < 10), according to common protocols. In the chronic toxicity tests, the surviving larvae were stored for body size measurements. Of the five metals analyzed, all were found in the six sampling points, but only Cu and Zn were present at higher levels than the "Threshold Effect Level" (TEL). The sediments of the six sites have some level of toxicity and the mortality in the acute and chronic toxicity tests was 100%. No statistically significant differences, between treatment and the control were found in the larval growth. Based on the metal contamination and the toxicity bioassay results, we consider it important to monitor sediments and to evaluate changes in land use in the adjacent water courses. (AU)

Este estudo objetivou avaliar a contaminação de metais nos sedimentos de cursos de água do Triângulo Mineiro e também analisar a toxicidade desses sedimentos utilizando larvas de Chironomusxanthus como organismo teste. Foram coletados sedimentos de três riachos (P1, P2 e P3) e também em três pontos do rio Uberabinha (P4, P5 e P6). Foram analisados Cu, Cr, Mn, Mg e Zn, e também realizados testes de toxicidade aguda e crônica. As amostras submetidas aos testes agudos foram categorizadas como tóxicas (mortalidade > 50%), evidências de toxicidade (mortalidade entre 10% e 50%) e não tóxicas (mortalidade <10%). Nos testes de toxicidade crônica, as larvas sobreviventes foram armazenadas para medidas do tamanho corporal. Dos cinco metais analisados, todos foram encontrados nos seis pontos amostrais, mas apenas Cu e Zn estavam presentes em níveis mais altos que TEL - Threshold Effect Level. Os sedimentos dos seis locais apresentam toxicidade ou indício de toxicidade e a mortalidade nos testes de toxicidade aguda e crônica foi de 100%. Não foram encontradas diferenças estatisticamente significativas, entre o tratamento e o controle, no crescimento larval. Com base na contaminação verificada e nos resultados dos bioensaios de toxicidade, consideramos importante monitorar os sedimentos e as mudanças no uso dos solos adjacentes aos cursos de água. (AU)

Oligochaeta (Annelida: Clitellata) in the Juruena River, MT, Brazil: species indicators of substrate types / Oligochaeta (Annelida: Clitellata) do Rio Juruena, MT, Brasil: espécies indicadoras em diferentes substratos

Abstract: Oligochaeta assemblages are important components in freshwater environments, where their abundance and composition may indicate aspects related to water quality and sediment. The lack of information about these communities in Brazilian aquatic environments, as well as the application of native species as bioindicators of lotic environmental, stimulated the conception of this paper. Thus, the aim was to study the community of aquatic Oligochaeta in selected stretches of the Juruena River (MT), thereby generating grounds for future environmental monitoring action in lotic ecosystems. For this purpose, samples were analyzed at bimonthly intervals during the period from January to November 2009, in stretches of the Juruena River (Amazon River Basin) located in the State of Mato Grosso (MT). Two methods were used to collect the organisms: a) "D" network in small clusters of fixed macrophytes in the sediment on the river banks; and b) Ekman-Birge dredge in fine sediment. Preliminary results were 584 organisms distributed in 22 taxa. Of these, 22 valid species were identified. This number corresponds to approximately 25% of the aquatic oligochaete species registered in Brazil. Of these species, Limnodrilus hoffmeisteri, Dero nivea and Pristina rosea can be associated with organic enrichment conditions and/or some level of environmental degradation.

Resumo: Comunidades de oligoquetos constituem importante componente em ambientes de água doce, onde sua abundância e composição podem indicar aspectos relacionados à qualidade da água e do sedimento. A carência de informações sobre estas comunidades em ambientes aquáticos brasileiros, bem como a aplicação de espécies nativas como bioindicadores de ambientes lóticos estimularam o desenvolvimento do presente trabalho. Assim, o objetivo foi estudar a comunidade de oligoquetos aquáticos em trechos selecionados do Rio Juruena (MT), gerando subsídios para futuras ações de monitoramento ambiental em ecossistemas lóticos. Métodos: Para isso foram analisadas amostras efetuadas em intervalos bimestrais durante o período de janeiro a novembro 2009, em trechos do Rio Juruena (Bacia Hidrográfica do Rio Amazonas) localizado no Estado de Mato Grosso (MT). Para coleta dos organismos foram utilizados dois métodos: a) rede em "D" em pequenos agrupamentos de macrófitas fixas no sedimento nas margens do rio; e b) draga Ekman-Birge em sedimento arenoso. Os resultados preliminares 584 organismos distribuídos em 22 táxons. Dentre estes, foram identificadas 22 espécies válidas. Esse número corresponde aproximadamente 25% das espécies de oligoquetos aquáticos registradas no Brasil. Destas espécies, Limnodrilus hoffmeisteri, Dero nivea e Pristina rosea podem ser associadas à condições de enriquecimento orgânico e/ou algum nível de degradação ambiental.

Effects of hydraulic retention time, co-substrate and nitrogen source on laundry wastewater anionic surfactant degradation in fluidized bed reactors.

The aim of this study was to evaluate the influence of hydraulic retention time (HRT) on linear alkylbenzene sulfonate (LAS) removal in fluidized bed reactors (FBRs). FBR1 (HRT of 8h) and FBR2 (HRT of 12h) were fed laundry wastewater with 18.6±4.1 to 27.1±5.6mg/L of LAS in the following conditions: ethanol and nitrate addition (Phases I, II and III), nitrate (Phase IV), ethanol (Phase V) and laundry wastewater (Phase VI). LAS removal was 93±12% (FBR1) and 99±2% (FBR2). In FBR1, nitrate influenced significantly on LAS removal (99±3% - Phase IV) compared to the phase without nitrate (90±15% - Phase V). In FBR1 the absence of ethanol was more favourable for LAS removal (99±3% - Phase IV) compared to ethanol addition (87±16% - Phase II). In FBR2, 99±2% LAS removal was found up to 436days. By microbial characterization were identified bacteria as Acinetobacter, Dechloromonas, Pseudomonas and Zoogloea.

First report of Epibiont ciliates (Ciliophora: Peritrichia) living on larvae of Leptophlebiidae (Ephemeroptera) from Brazil

ABSTRACT Epibiosis was understood as a commensalism relation between two or more organisms. However, some studies have shown that epibionts can cause deleterious effects to their host. Here, we reported the first report of epibiosis between protozoa Epibiont ciliates (Ciliophora: Peritrichia) living on larvae of Ephemeroptera from Brazil.

Assessment of chromium contamination in the Monte Alegre stream: a case study

The aim of this work was to study the contamination by chromium in the sediments of the Monte Alegre stream and in the larvae of Odonata and the possible impact caused by them on the stream macroinvertebrates community. It was found that chromium contaminated the sediments and the aquatic biota. Although, the stream macroinvertebrates community structure did not appear to be modified.

Evaluating the use of predatory insects as bioindicators of metals contamination due to sugarcane cultivation in neotropical streams.

Streams located in areas of sugarcane cultivation receive high concentrations of metal ions from soils of the adjacent areas causing accumulation of metals in the aquatic sediment. This impact results in environmental problems and leads to bioaccumulation of metal ions in aquatic organisms. In the present study, metal concentrations in different predatory insects were studied in streams near sugarcane cultivation and compared to reference sites. Possible utilisation of predatory insects as bioindicators of metal contamination due to sugarcane cultivation from 13 neotropical streams was evaluated. Ion concentrations of Al, Cd, Cr, Cu, Zn, Fe, and Mn in adult Belostomatidae (Hemiptera) and in larvae of Libellulidae (Odonata) were analysed. Nine streams are located in areas with sugarcane cultivation, without riparian vegetation (classified as impacted area) and four streams were located in forested areas (reference sites). Metal concentrations in insects were higher near sugarcane cultivations than in control sites. Cluster analysis, complemented by an ANOSIM test, clearly showed that these insect groups are good potential bioindicators of metal contamination in streams located in areas with sugarcane cultivation and can be used in monitoring programmes. We also conclude that Libellulidae appeared to accumulate higher concentrations of metals than Belostomatidae.

Relationship between sugar cane cultivation and stream macroinvertebrate communities

The aim of this work was to study the influence of the sugar cane cultivation on the macroinvertebrate communities of 11 streams under different land uses. Analysis of the sediment (organic matter contents and metals) and water complemented the study. Ninety six macroinvertebrates taxa were identified, of which 54 were Chironomidae and 42 of other aquatic macroinvertebrates. The streams located in the areas of sugar cane culture and pasture presented low taxa and a great participation of Chironomidae (78% of the total). In contrast, the streams located in the areas with riparian vegetation presented a rich aquatic fauna with less participation of Chironomidae (60% of the total).

No Estado de São Paulo, a cultura de cana-de-açúcar tem se expandido significativamente nos últimos 15 anos, sendo este o maior produtor nacional com uma produção anual de 200.10(6) t em uma área de 2.5. 10(6) ha. O cultivo da cana-de-açúcar, aliado ao problema da devastação das matas ciliares tem ocasionado impactos sobre os recursos hídricos das áreas adjacentes. Nesse estudo foi avaliada a influência da atividade canavieira sobre a comunidade de macroinvertebrados aquáticos de 11 córregos sobre diferentes usos da terra. Análises do sedimento (matéria orgânica e metais) e da água complementaram o estudo. Noventa e seis táxons de macroinvertebrados foram coletados, sendo 54 de Chironomidae e 42 de outros macroinvertebrados. Os córregos localizados em áreas com atividade canavieira e pastagens, apresentaram uma baixa variedade faunística com predomínio de larvas de Chironomidae (78% do total). Ao contrário, os córregos localizados em áreas com vegetação ripária apresentaram uma rica fauna aquática com menor participação de larvas de Chironomidae (60% do total).

Ciclo de vida de duas espécies de Goeldichironomus (Diptera, Chironomidae) / Life cycle of two Goeldichironomus species (Diptera, Chironomidae)

Duas espécies de Goeldichironomus foram criadas em condicões de laboratório (21ºC -26ºC), com alimento para peixes do tipo TetraMin® e alimento para aves Avemicina Purina®, para se obter informacões bionômicas e analisar a viabilidade de cultivo para fins de bioensaios. As massas ovígeras das duas espécies, foram mantidas em placas de Petri até a eclosão das lárvulas. A duracão média do desenvolvimento larval até a emergência dos adultos foi de 28 (23-34) dias para Goeldichironomus maculatus Strixino & Strixino, 1991 e 20 (18-22) dias para Goeldichironomus luridus Trivinho-Strixino & Strixino, 2005. Os estádios larvais para as duas espécies foram determinados através da relacão entre o tamanho da cabeca e o tamanho do corpo. Essas medidas foram usadas para determinar as curvas de crescimento e estimar a taxa de crescimento diário das duas espécies. As criacões ocorreram de forma satisfatória, com rápido crescimento larval e baixa taxa de mortalidade, mas, não houve acasalamento em condicões de laboratório.