Use of termite workers Cornitermes cumulans as soil bioindicator of insecticide residues

Foi verificado que operárias de cupim Cornitermes cumulans Kollar 1832, mostram-se sensíveis à determinação do poder residual de inseticidas no solo. O estudo foi realizado com os inseticidas cypermethrin, deltamethrin, carbofuran e aldrin em solo barro-areno-argiloso com pH 5,6 e MO 2,2%. O solo foi tratado com quantidades de produto cinco vezes maior ao das respectivas CL50 encontradas para as operárias de cupim. Os ensaios foram desenvolvidos no laboratório, em placas de Petri e no interior de tubos de vidro. Verificou-se que o inseticida aldrin não é percebido pelos cupins no solo, enquanto os inseticidas cypermethrin, deltamethrin e carbofuran são imediatamente detectados. Os dois inseticidas piretróides modificam o comportamento dos cupins, diminuindo suas atividades e provocam o seu agrupamento, demonstrando sua ação repelente.It was verified that workers of termites Cornitermes cumulans Kollar, 1832 were sensible to the determination of residual insecticide power in soil. This study was developed with the insecticides cypermethrin, deltamethrin, carbofuran and aldrin, in a mud-sandy-clay soil with pH 5.6 and organic matter 2.2%. The soil was treated with a dosage five times higher than the LC50 values obtained for termite workers in the laboratory. The experiments were developed on laboratory, in Petri dishes and in glass tubes. It was found that the insecticide aldrin is not perceptible by the termite workers in the soil; on the other hand cypermethrin, deltamethrin and carbofuran were immediately detected. Both pyrethroid insecticides modified the behavior of the termites, causing less activity and causing their grouping, thus showing their repellent action.

Persistence of two pyrethroids insecticides in a mud-sandy-clay soil under field conditions

Verificou-se a persistência dos inseticidas piretróides cypermethrin e deltamethrin num solo barro-areno-argiloso, em condições de campo, comparados com os inseticidas carbofuran e aldrin. A avaliação foi feita com auxílio de operárias de cupim Cornitermes cumulans Kollar, 1832, utilizadas como bioindicadores. O solo foi tratado com quantidades cinco vezes maior do que os valores das CL50 obtidos para os insetos em laboratório. As avaliações foram feitas a cada sete dias, coletando-se amostras de solo no campo que foram padronizadas no laboratório quanto ao peso e umidade para receberem os bioindicadores. Foram feitas avaliações em solo isento de plantas e com cultivo de trigo. A presença de plantas diminuiu a eficiência do inseticida cypermethrin. Somente após o 38o dia os cupins iniciaram a escavação de túneis no solo tratado com os inseticidas piretróides, enquanto que nos tratamentos com aldrin e carbofuran, o mesmo ocorreu no 17o e 24o dias, respectivamente. Os inseticidas piretróides tiveram perda mais acentuada do poder residual nas primeiras três semanas, contudo, ao longo do tempo, mantiveram-se mais estáveis e foram detectados pelo método durante 150 dias. The persistence of two pyrethroid insecticides, cypermethrin and deltamethrin was verified in a mud-sandy-clay soil under field conditions in relation to carbofuran and aldrin insecticides. The evaluation was done with the add of termite workers Cornitermes cumulans Kollar, 1832 as bioindicators. The soil was treated with a dosage five times higher than the LC50 values obtained for the insects in the laboratory. The evaluations were done every seven days, taking soil samples on the field and adjusting it in relation to moisture and weight to receive the bioindicators. The evaluations were done on soil without plants and on the ones cultivated. Wheat plant presence reduced the efficiency of the insecticide cypermethrin. Only after the 38th day the termites began to dig their tunnels in the soil treated with pyrethroids, while for the treatments with aldrin and carbofuran it happened on the 17th and 24th day, respectively. The pyrethroid insecticides had the highest lost of their residual on the first three weeks, however, during the period, they were more stable and were detected by the method during 150 days

Systems and rates of aerial application of fungicides in irrigated rice

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

Epigeic ants (Hymenoptera: Formicidae) in vineyards and grassland areas in the Campanha region, state of Rio Grande do Sul, Brazil

In order to characterize the epigeic myrmecofauna in fields and vineyards in the physiographic region of Campanha, located in the Pampa biome, state of Rio Grande do Sul, inventories were conducted on three farms. On each farm, samples were collected in three environments: the rows in the vineyards, the spaces between rows in the vineyards, and the adjacent areas, with vegetation similar to that which preceded the establishment of crops. In each environment, 20 points were sampled using pitfall traps. We collected 72 species distributed among 24 genera and seven subfamilies. The study provides the first inventory of the ant fauna in the region, contributing with new records for the state of Rio Grande do Sul and for Brazil. It is hoped that this inventory will stimulate further studies on the biodiversity of this biome that is still poorly known