We tested the bioactivity of aqueous extracts of Ludwigia spp. (Myrtales: Onagraceae) on the biological cycle of Plutella xylostella. We assessed the duration of and viability during the larval, pupal and adult phases, as well as the influence of the extracts on the fecundity and hatching of P. xylostella eggs. Subsequently, we phytochemically screened the extracts. The extracts of L. tomentosa and L. longifolia reduced the pupal weight instead of prolonging the larval stage of P. xylostella. The L. tomentosa effect caused higher larval mortality and reduced the fecundity and hatching of P. xylostella eggs, and L. sericea reduced the egg survival. The phenolic compounds—flavonoids, condensed tannins and alkaloids—were more abundant in L. nervosa, L. tomentosa, L. sericea and L. longifolia. The L. tomentosa, L. longifolia and L. sericea extracts were bioactive, and these species showed the best results regarding their ability to control P. xylostella populations, because these plants produce substances able to inhibit food consumption and interfere with the morphological and physiological transformations of the offspring and the oviposition of adults.

The diet of macroinvertebrates sampled in leaf-bags incubated in a tropical stream was analyzed on a spatial scale (one forested and one deforested area) and on a temporal scale (dry and rainy seasons). The macroinvertebrates were mostly represented by detritivores specialized in fine detritus (69%), followed by generalist detritivores (10% with a diet based on fine and coarse detritus), carnivores (10%), omnivores (8%), and one detritivore genera specialized on coarse detritus (3%). The detritivores exhibited a broad spatial and temporal distribution and were represented mainly by Ephemeroptera, Trichoptera and Diptera. Phylloicus sp. (Trichoptera) consumed mostly coarse detritus (CPOM) and can be classified as the unique specialist shredder in this stream. Carnivores were represented by Anacroneuria sp. (Plecoptera), Hetaerina sp. and Heteragrion sp. (two Odonata). Omnivory was observed for Anacroneuria sp. and Smicridea sp. (Trichoptera), which evidently varied spatially and temporally in the proportion of the food consumed. The high diversity and the wide distribution of the taxa that used organic matter as food resource demonstrated the great importance of this food item to the macroinvertebrates community in this tropical stream

RESUMO Neste trabalho foi avaliado o crescimento da microalga Pseudokirchneriella subcapitata em meio de cultivo alternativo NPK (20:05:20) contaminado com metais pesados. O primeiro tratamento consiste do controle sem a adição de contaminante, enquanto os demais foram contaminados com AlCl 3 , FeSO 4 e ZnSO 4 e os três metais. Nos resultados obtidos, o controle foi o único que apresentou crescimento positivo contínuo, enquanto o tratamento contendo todos os metais obteve maior densidade e maior taxa de crescimento exponencial. O tratamento contaminado com ZnSO 4 obteve o menor potencial de produção. Apesar dos valores apresentados, todos os tratamentos apresentaram crescimento positivo no final do ensaio, sendo possível atribuir à microalga um elevado potencial de produção em água contaminado por metais. Palavras-Chave: água residual; biorremediação; Chlorophyceae; crescimento exponencial; densidade algal

Estudo parcial do plano de manejo do parque estadual das Várzeas do Rio Ivinhema como subsídio para ações estratégicas / Partial study of the management plan of parque estadual das Várzeas do Rio Ivinhema as a subsidy for strategic actions

The applications of microalgae are being increasingly explored, as they have a high rate of cell duplication and accumulation of lipids, ranging from 20-50% of their dry weight, reaching up to 80% under appropriate conditions. Their cultivation in artificial conditions has also increased, which has made it important to explore different microalga quantification methods and evaluate its growth kinetics. For algal quantification, it appears that both quantification methods by direct counting in a Neubauer chamber (density) and indirect counting methods such as reading in spectrophotometry (optical density) and dry weight (biomass), are important to validate the results quantification. The objective of this study was to verify the existence of a functional relationship between the variables used to quantify the microalgae Chlorella sorokiniana. For this purpose, linear regression analysis was applied to the variables of cell density, optical density, and dry biomass that were obtained by cultivating the microalgae at different concentrations. Using the equations generated from the regression analysis in Chlorella sorokiniana, it was possible to obtain ​​cell density values between 3 and 3.8 × 106 mL-1 and dry biomass values between 0.1 and 4.3 mg.mL-1 from the optical density values acquired using spectrophotometry with extreme precision, and this method was found to be highly feasible.