RESUMO Estudou-se o desempenho dos bicos defletor e cônico, com taxas de aplicação de 20 e 30 L ha-1, e atomizador rotativo de discos com volumes de 10 e 15 L ha-1. O ensaio foi realizado com uma calda de fungicida composta da Azoxistrobina + Difenoconazol (Priori + Score®), onde se avaliou a densidade e penetração de gotas no dossel das plantas com auxílio de papel hidrossensível e a distribuição dos princípios ativos na planta através da análise cromatográfica. Em todos os tratamentos a penetração das gotas no estrato médio foi 26% e no inferior 23% em relação ao topo da cultura, resultando numa média de 25% de penetração de gotas no dossel foliar. Os princípios ativos distribuíram-se em maior quantidade no estrato superior da planta, em estádio R3. Para o mesmo peso, à parte superior da cultivar de arroz Puitá Inta CL possui área foliar 6,4 vezes maior em relação a parte inferior. Conclui-se que o maior volume de aplicação proporciona maior densidade de gotas no estrato superior foliar e que todos os sistemas e volumes de aplicação promoveram similar penetração de gotas no dossel.

ABSTRACT The present research studied the performance of flat-fan and hollow-cone nozzles, with application rates of 20 and 30 L ha-1, and rotary disc atomizer with application rates of 10 and 15 L ha-1. The test was conducted with a fungicide spray tank composed of Azoxystrobin + Difenoconazole, in which the density and penetration of droplets into the canopy were evaluated using a water-sensitive paper and the distribution of the active ingredients in the plant was evaluated through the chromatographic analysis. Higher application rates resulted in higher droplet density in the upper stratum of plants. In all treatments, the penetration of the droplets was 26% into the middle stratum and 23% into the lower stratum, in relation to the top of the crop, resulting in an average 25% penetration of droplets into the leaf canopy. The active ingredients were distributed in greater quantity in the upper stratum of the plant. For the same weight, the upper part of the ‘Puitá Inta CL’ rice cultivar has a leaf area 6.4 times larger than the lower part. It was concluded that higher application rate leads to higher droplet density in the upper stratum of the leaf canopy and that all systems and application rates promoted similar penetration of droplets into the canopy.

El bioma de la Pampa en el sur de Brasil tiene pasturas con alta biodiversidad. Dado el rápido crecimiento del cultivo de Eucalyptus sobre estas áreas de pasturas y el poco conocimiento de la fauna de arañas de suelo, se planteó hacer un reconocimiento de las arañas que ocurren allí y una evaluación cuantitativa de las diferencias en esta fauna entre los dos ambientes. Las áreas de estudio incluyeron cinco fincas cada una con los dos ambientes, pasturas nativas y plantaciones de Eucalyptus. La densidad de arañas fue de 6,53 (±1,01d.e.) individuos/m-2 en el silvicultivo y de 3,88 individuos/m-2 (±0,73) en las pasturas. Este resultado podría deberse a que las arañas encontraron más refugios bajo una capa de hojarasca más densa en el silvicultivo que en las pasturas donde pueden estar más expuestas entre otras cosas a sus depredadores. Se capturaron 24 familias de arañas, las más abundantes y diversas fueron Salticidae y Linyphiidae. Diecinueve familias se encontraron en el silvicultivo y 21 en las pasturas. Se identificaron 51 morfoespecies de arañas adultos, la más abundante es Guaraniella mahnerti. La abundancia de adultos fue marginalmente mayor en las áreas de silvicultivo. La densidad de especies no fue diferente entre ambientes o sitios, pero la equitatividad fue significativamente mayor para las pasturas. Este mayor balance en las abundancias de especies de los ensamblajes de arañas en las pasturas sugiere un ambiente más sano comparado con el de un monocultivo. El gremio más abundante fue el de las cazadoras cursoriales. Aun siendo un inventario rápido de la diversidad de arañas, la información obtenida aquí es un aporte significativo a nuestro conocimiento de cómo esta nueva tendencia económica en silvicultura afecta los ambientes nativos.

The Pampa biome in southern Brazil has grassland areas with high biodiversity. Given the fast advance of Eucalyptus silviculture over grassland areas in this biome, and the scant knowledge on the soil spider fauna in these landscapes, we aimed to provide a first view of spiders occurring there and to quantitatively evaluate differences in the spider fauna between the two environments. Study areas included five farms each with the two environments, native grassland and Eucalyptus plantation. Spider densities were 6.53 (±1.01s.e.) individuals/m-2 in silviculture and 3.88 individuals/m-2 (±0.73) in grassland. This could be due to spiders finding more shelter sites underneath a denser silviculture litter than in the grassland where they could be more exposed, for example, to their own predators. Twentyfour spider families were captured; the most abundant and diverse were Salticidae and Linyphiidae. Nineteen families occurred in the silviculture and 21 in the grassland. For adult spiders, 51 morphospecies were determined, the most abundant being Guaraniella mahnerti. Adult abundance was marginally significant for environment, with silviculture areas having more spiders. Species density did not differ between environments or sites, but evenness was significantly higher for the grassland. This better balance in species abundances for spider assemblages in grasslands suggests a healthier environment compared to a monoculture. The most abundant guild was that of the running hunters. Even as a rapid spider diversity inventory, the information gathered here adds considerably to our knowledge on how this new economic upsurge in silviculture affects native environments.

Propôs-se, com este trabalho, avaliar e monitorar a presença de agrotóxicos nas águas do canal São Gonçalo e do rio Piratini, localizados na região sul do Estado do Rio Grande do Sul. Durante o cultivo do arroz irrigado foram coletadas, em cinco datas diferentes, três amostras de água do rio Piratini e quatro do canal São Gonçalo. A metodologia empregada na análise dos resíduos de quinclorac, carbofuran e clomazone, foi a Cromatografia Líquida de Alta Eficiência com Detecção por Arranjo de Diodos (HPLC-DAD) e, para os resíduos de fipronil e betaciflutrina, a Cromatografia Gasosa com Detecção por Captura de Elétrons (GC-ECD). Os resultados mostraram que da semeadura à colheita a quantidade de resíduos de agrotóxicos na água diminuiu; observou-se também que no ponto mais baixo (Laranjal), maior número de análises de águas com resíduos foi detectado (onze análises com resíduo de agrotóxico). O inseticida carbofuran e o herbicida quinclorac foram os produtos que apresentaram resíduos com maior freqüência (16 e 15, respectivamente) enquanto o clomazone e o fipronil indicaram sete amostras com resíduos cada uma e a betaciflutrina não foi detectada em nenhum local.

The objective of this study was to evaluate and to monitor the presence of pesticides in the waters of the São Gonçalo channel and the Piratini river located in the southern region of the State of Rio Grande do Sul. During the rice growing season, water samples were collected five times, three samples from the river Piratini and four from the São Gonçalo canal. The methodology used for the analysis of residues of quinclorac, carbofuran and clomazone was the High Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD) and for residues of the pesticides fipronil and betacyfluthrin, the Gas Chromatography with Electron Capture Detection (GC-ECD) was used. Results show that from sowing to harvesting the quantity of pesticide residues in water decreased. It was also observed that, at the lowest point (Laranjal), a greater number of analyses contaminated with residues was detected (11 samples with some type of pesticide). Insecticide carbofuran and herbicide quinclorac were pesticides that presented residues more frequently (16 and 15 times, respectively). Clomazone and fipronil were present in each of the 7 samples with residues and betacyfluthrin was not detected at any site.

The thermal requeriments of Culex quinquefasciatus (Say, 1823) and the number of generations in the year are determined. The colony to obtain eggs, larvae, pupae and adults was established under laboratory conditions. Every stage was maintained at constant temperature (15, 20, 25 and 30ºC), in cameras, with relative humidity of 80% ± 5 and photophase of 12 hours, to settle down the thermal inferior limit and the thermal constant by the method of the hiperbole. The thermal inferior limit to phase of egg, larvae and pupa were respectively 10.0, 9.1 and 10.2ºC, and 10.2ºC to all the aquatic cycle, with a thermal constant of 207.2 degree-day, with the mean of 15.5 generations per year in Pelotas, State of Rio Grande do Sul.

O consumo médio de área foliar da lagarta-da-folha Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), em função do sexo e do ínstar, foi determinado em condições de laboratório em folhas de arroz, das cultivares BR-IRGA 410 e Embrapa 6-CHUÍ. Não houve diferença significativa no consumo total de área foliar das duas cultivares pelas lagartas que resultaram em machos e fêmeas. Ocorreram diferenças significativas entre ínstares, sendo o maior consumo constatado no 7º ínstar. A duração do estágio larval não diferiu para machos e fêmeas nas duas cultivares, entretanto houve diferença significativa na duração dos ínstares, independente do sexo. O 7º ínstar foi o mais longo, onde concentrou-se o maior consumo foliar diário. No consumo médio diário foram observados valores muito próximos tanto para machos como para fêmeas dentro dos cinco ínstares analisados nas duas cultivares testadas, constatando-se um aumento considerável a partir do 5º ínstar.

Mean foliage consumption by fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) was measured, for each sex and instar, in laboratory conditions, on rice leaves of cultivars BR-IRGA 410 and Embrapa 6-CHUÍ. No significant difference of total leaf consumption was observed among caterpillars that developed males or females. Differences were observed among instars with the seventh one being responsible for the higher total consumption. Duration of larval stage was not different for males and females on both cultivars but significant differences were observed in the duration of different instars, independently of sex. The seventh instar was the longest and represented the higher daily consumption. Average daily consumption was similar to male and females in the instars tested, in both cultivars, and increased considerably after the fifth instar.