Microbial pest control agents or entomopathogens have been considered an interesting alternative to use instead of chemical insecticides. Knowledge of ecotoxicity data is very important to predict the hazard of any product released in the environment and subsidize the regulation of these products by governmental agencies. In the present study four new Brazilian strains of Bacillus and one fungus were tested to evaluate their acute toxicity to the microcrustacean Daphnia similis, the snail Biomphalaria glabrata and the dung beetle Digitonthophagus gazella. The microcrustaceans and the snails were exposed to entomopathogens in synthetic softwater and the beetles were exposed directly in cattle dung. Obtained data reveal low susceptibility of the non-target species to tested microorganisms, with lethal concentrations being observed only at much higher concentrations than that effective against target insects. These results show that the tested strains are selective in their action mode and seem to be non-hazardous to non-target species.

Bioinsecticides from Bacillus thuringiensis (Bt) are widely used around the world in biological control against larval stages of many insect species. Bt has been considered a biopesticide that is highly specific to different orders of insects, non-polluting and harmless to humans and other vertebrates, thus becoming a viable alternative for combating agricultural pests and insect vectors of diseases. The family of Bt δ-endotoxins are crystal-protein inclusions showing toxicity to insects' midgut, causing cell lysis leading to starvation, septicemia and death. The aim of this study is to evaluate the genotoxic potential of recombinant Bt spore-crystals expressing Cry1Ia, Cry10Aa and Cry1Ba6 on peripheral erythrocyte cells of Oreochromis niloticus, through comet assay, micronucleus (MN) test and nuclear abnormalities (NA) analysis. Fish (n = 10/group) were exposed for 96 h at 10(7) spores 30 l(-1), 10(8) spores 30 l(-1) or 10(9) spores 30 l(-1) of Bt spore-crystals. Cry1Ia showed a significant increase in comet cells at levels 1 and 2, but not at levels 3 and 4, so it was not mutagenic nor did it induce MN or NA. These three spore-crystals showed some fish toxicity at only the highest exposure level, which normally does not occur in the field.

ABSTRACT. This study evaluated the efficiency of two bioindicators, fecal coliforms and ecotoxicity tests, set out in CONAMA Resolution 274/00 and CONAMA Resolution 357/05, in assessment of water quality. For this study, Lake Paranoá, Federal District of Brazil, was chosen, since it is a water body directly contaminated by effluents from a sewage treatment plant. Four sampling points were chosen in accordance with the map of recreational water quality published weekly by CAESB/DF, after analysis of fecal coliforms. Samples from these points were collected for 6 months and tested on Danio rerio fish (acute toxicity) and on the microcrustacean Ceriodaphnia dubia (acute and chronic toxicity), besides measuring chemical and physico-chemical parameters. The data obtained show great consistency between the observed biological parameters, suggesting that in this urban aquatic environment, under great anthropogenic pressure, the fecal coliform bioindicator seems to be more restrictive and enough to evaluate the safety of surface water.Keywords: water quality, ecotoxicity tests, fecal coliforms, Paranoá lake, recreational water, safety.RESUMO. Comparação entre a eficiência de dois bioindicadores para a determinação da qualidade de águas superficiais em um ambiente urbano. Este trabalho comparou a eficiência dos bioindicadores coliformes fecais ou termotolerantes e ensaios de ecotoxicidade, propostos pelas Resoluções Conama 274/00 e Conama 357/05, na avaliação da qualidade de água. Para a realização desse estudo foi escolhido o Lago Paranoá, Brasília, Distrito Federal, por ser um corpo hídrico impactado diretamente pelo lançamento de efluentes de uma estação de tratamento de esgotos. Foram definidos quatro pontos de acordo com o mapa de balneabilidade, publicado semanalmente pela Caesb/DF, em função do teor de coliformes termotolerantes. Amostras desses pontos colhidas durante seis meses foram testadas com o peixe Danio rerio (toxicidade aguda) e o com o microcrustáceo Ceriodaphnia dubia (toxicidade aguda e crônica), além da determinação de parâmetros químicos e físico-químicos. Os resultados obtidos mostraram grande equivalência entre os parâmetros biológicos observados, sugerindo que nesse ambiente sob grande influência antrópica, o bioindicador coliformes termotolerantes foi mais restritivo e suficiente para avaliar a segurança das águas superficiais.

Soils derived from ultramafic rocks have a mineralogy rich in metals like Co, Cr, Fe and Ni, and the process of extracting these metals from soil generates highly metallic waste. When disposed near of water bodies these residues pose a risk on the aquatic environment. Two fish species are used in ecotoxicity tests worldwide: Danio rerio (zebrafish), an Asian species, and Oreochromis niloticus (tilapia), an African one. However, Hyphessobrycon eques (mato grosso), a native of South America and found in Brazilian rivers, is as yet little used in ecotoxicity tests. The aims of this study were to evaluate the acute toxicity of the metals Co, Cr, Fe and Ni to the fish D. rerio, O. niloticus and H. eques, and compare its susceptibility. Tests were conducted following the recommendations of the Brazilian Association for Technical Standardization (ABNT). Stock solutions were prepared with the analytical reagents CoCl 2 .6H 2 O; K 2 Cr 2 O 7 ; FeCl 3 .6H 2 O e NiCl 2 .6H 2 O. The quantification of metals was carried out in the stock solutions by ICP-AES. The dilution water used was synthetic softwater pH 7.3±0.1, hardness 43 mg L-1 ; DO 95% and temperature 25±1°C. To perform static tests 10 fish from each species were exposed for 96 hours, in duplicate, to different concentrations of the metals tested. The measured 96-hr initial lethal concentrations LC(I) 50 of metals Co, Cr, Fe and Ni, calculated by the Trimmed

Resumo IntroduçãoOs grandes avanços científicos que ocorreram recentemente na área da Biologia, especialmente na Genética, geraram um volume muito grande de novas informações e de conhecimentos mais complexos nesta área (VILAS-BOAS, 2006).