Medicinal plant extracts on the control of Diabrotica speciosa (Coleoptera: Chrysomelidae) / Extratos de plantas medicinais no controle de Diabrotica speciosa (Coleoptera: Chrysomelidae)

The aim of this study was to evaluate the insecticidal effect of aqueous, alcoholic, and oil extracts from leaves of eight medicinal plants against Diabrotica speciosa prepared at five concentrations. The extracts that used commercial soybean oil as solvent showed the highest D. speciosa mortality due to the solvent itself, regardless of the used plants and their concentrations. Thus, commercial soybean oil was discarded as solvent since at these volumes it would cause serious phytotoxicity problems. After 24 hours of exposure of the pest to the extracts, the highest D. speciosa mortality values were observed for Copaifera langsdorfii and Chenopodium ambrosioides extracts, both in 5% alcohol, and Artemisia verlotorum, in 10% water. However, in the last mortality assessment (48 h), C. langsdorfii extract in 5% alcohol showed higher mortality of this pest, followed by C. ambrosioides extract in 5% alcohol, compared to the remaining plants.

O objetivo deste trabalho foi avaliar o efeito inseticida de extratos aquosos, alcoólicos e oleosos de folhas de oito plantas medicinais contra Diabrotica speciosa preparadas em cinco concentrações. Os extratos que utilizaram óleo de soja comercial como solvente apresentaram as maiores mortalidades de D. speciosa em função do próprio óleo, independentemente das plantas utilizadas em suas concentrações. Sendo assim, o óleo de soja comercial foi descartado como solvente, pois nestes volumes acarretaria sérios problemas de fitotoxidade. Após 24 horas de exposição da praga aos extratos, os maiores valores de mortalidade de D. speciosa foram observados nos extratos de Copaifera Langsdorfii e de Chenopodium ambrosioides, ambos em álcool 5%, e de Artemisia verlotorum, em água 10%. Entretanto, na última avaliação de mortalidade (48 h), o extrato de C. langsdorfii em álcool a 5% apresentou maior mortalidade dessa praga, seguida pelo extrato alcoólico a 5% de C. ambrosioides comparada às demais plantas.

Effect of dietary (n-3) highly unsaturated fatty acids on growth and survival of fat snook (Centropomus parallelus, Pisces: Centropomidae) larvae during first feeding

The effect of rotifers, Brachionus rotundiformis (S-type), fed three different diets: A (rotifer fed Nannochloropsis oculata), B (rotifer fed N. oculata and baker's yeast, 1:1), and C (rotifer fed N. oculata and baker's yeast, 1:1, and enriched with Selcoâ), was evaluated based on the survival, growth and swim bladder inflation rate of fat snook larvae. Rotifers of treatment A had higher levels (4.58 mg/g dry weight) of eicosapentaenoic acid (EPA) than B (1.81 mg/g dry weight), and similar levels (0.04 and 0.06 mg/g dry weight, respectively) of docosahexaenoic acid (DHA). Rotifers of treatment C had the highest levels of EPA (13.2 mg/g dry weight) and DHA (6.08 mg/g dry weight). Fat snook eggs were obtained by spawning induction with human chorionic gonadotropin. Thirty hours after hatching, 30 larvae/liter were stocked in black cylindric-conical tanks (36-liter capacity). After 14 days of culture, there were no significant differences among treatments. Mean standard length was 3.13 mm for treatment A, 3.17 mm for B, and 3.39 mm for C. Mean survival rates were very low (2.7 percent for treatment A, 2.3 percent for B, and 1.8 percent for C). Swim bladder inflation rates were 34.7 percent for treatment A, 27.1 percent for B, and 11.9 percent for C. The lack of differences in growth and survival among treatments showed that the improvement of the dietary value of rotifer may not have been sufficient to solve the problem of larval rearing. Some other factor, probably pertaining to the quality of the larvae, may have negatively influenced survival