Lourdes Silva de Figueiredo

Chemical study and larvicidal activity against Aedes aegypti of essential oil of Piper aduncum L. (Piperaceae)

Piper aduncum L. is used in folk medicine to treat respiratory and inflammatory diseases. The aim of this study was to analyze the essential oil from leaves of P. aduncum collected in the Brazilian Cerrado, North of Minas Gerais, as well as to evaluate the larvicidal activity of this oil and of its major constituent. The essential oil was analyzed by gas chromatography coupled to flame ionization detector and gas chromatography coupled to mass spectrometry that allowed characterizing 23 compounds (monoterpenes: 90.4%; sesquiterpenes: 7.0%). The major component was 1,8-cineole (53.9%). This oil showed to be very different from those obtained from the same species. Larvae of A. aegypti were exposed to different concentrations of the essential oil and 1,8-cineole. The mortality rate of 100% was obtained after 24 h of treatment with the oil at concentrations of 500 and 1,000 ppm. After 48 h of treatment, the mortality rate was 80% and 50% for concentrations of 250 and 100 ppm, respectively. The LC₅₀ obtained after 24h was estimated in 289.9 ppm and after 48 h was 134.1 ppm. The major compound 1,8-cineole showed no larvicidal activity.

Growth study and essential oil analysis of Piper aduncum from two sites of Cerrado biome of Minas Gerais State, Brazil

Piper aduncum L., Piperaceae, stands out due to its biological activities, however, it is still found in the wild and little is known about its agronomic point of view. The aim of this study was to evaluate the growth and to analyze the chemical composition of essential oils from leaves of P. aduncum collected in two different sites of Cerrado as well as in cultivated plants. The cultivation was installed out in a greenhouse using cuttings of adult specimens. Essential oils were obtained from fresh leaves. Plants from the two studied locations showed erect growth habit and behavior of linear growth. The essential oils composition of P. aduncum from Bocaiuva did not differ between wild and cultivated plants, as the major substance identified as 1,8-cineole. The plants from Montes Claros site showed a distinct concentration for the two samples, being the major substance characterized as transocimene (13.4%) for wild and 1,8-cineole (31.3%) for cultivated plants. Samples from both locations showed a similar essential oil composition in cultivars. Our results showed that P. aduncum cultivation is feasible and the variation in chemical composition of the two sites may indicate an environmental influence, since chemical and isoenzyme analysis did not show great differences.

Teor de óleo essencial de alecrim-pimenta em função do horário de colheita

The pepper-rosmarin is an important medicinal plant, native of Northeast of Brazil, that, because of its essential oil, presents great antifungal and antibacterial potential. One of the factors that affect the secondary metabolites content of plants is the harvest time, thus, the knowledge of this factor subsidizes the decisions agronomic species, favoring the increase of essential oil content at the harvest moment. Thus, the aim of this research was to evaluate the effect of harvest time on the essential oil production of pepper-rosmarin (Lippia sidoides Cham.). The experiment was carried out in the Instituto of Ciencias Agrarias of Universidade Federal of Minas Gerais (ICA/UFMG), Montes Claros, Minas Gerais, Brazil. It was installed in a randomized block design, with five treatments consisted by harvest times (6:00, 9:00, 12:00, 15:00 and 18:00) with six replications (number of collections in each treatment). The leaves were obtained from stock plants of medicinal vegetable garden of ICA/ UFMG. The essential oil was obtained by hydrodistillation in a Clevenger apparatus. The regression analysis presented a cubic effect to the essential oil content, being that the highest value, 5,78% in relation to dry matter, was obtained at 9h59min. Therefore, it was recommended the harvest time of pepper-rosmarin leaves next to 10h.

Water stress before harvest of pepper-rosmarin

The objective of this work was to assess the effect of different periods of water stress before harvest of pepper-rosmarin (Lippia sidoides) on the contents of essential oil and flavonoids. The experiment was carried out during 270 days of cultivation, with drainage lysimeters, in a completely randomized block design with five treatments: 0, 2, 4, 6, and 8 days of water suppression before harvest, with four replicates. Fresh and dry matter yield, essential oil content, total flavonoids content, and water potential and temperature of leaves were determined. There was a decrease of approximately 50% in oil content and of 60% in total flavonoid content with the reduction of leaf water potential in 0.3 MPa. Essential oil is more sensitive to water stress than total flavonoids.

NPK and flavonoids affecting insect populations in Dimorphandra mollis seedlings

The study evaluated the influence of different levels of nitrogen (N), phosphorus (P) and potassium (K), and flavonoids on the population of insects in Dimorphandra mollis Benth (Leguminosae) seedlings. The treatments associated with the highest level of attacks by Frankliniella schulzei (Trybon) (Thysanoptera: Thripidae) were 600 mg dm -3 of P and 50 mg dm -3 of K. The highest level of attacks by Coccidae occurred for 300 of P and 150 and 250 mg dm -3 of K. The last two treatments also exhibited the highest level of attacks by Pseudococcidae. On the other hand, the control exhibited higher levels of flavonoids and a lower level of insect attacks. We observed a small positive effect of N levels on attack by F. schulzei. The levels of N, P and K negatively affected the levels of flavonoids in the leaves of D. mollis. We detected no significant effects of flavonoid levels on the populations of Coccidae, Pseudoccocidae and F. schulzei. Higher numbers of Coccidae and Pseudococcidae were observed in the abaxial face of apical leaves. However, higher numbers of F. schulzei were observed on the adaxial face at lower heights in the canopy. The preferred treatment for the production of D. mollis seedlings is the control (without fertilization) because it showed higher flavonoid levels than other treatments and did not result in higher insect numbers.

Growing of tropical black sage and chemical composition of the essential oil

The objective of this study was to evaluate the influence of spacing and mulch on biomass production, chemical composition and production of essential oil of tropical black sage. A randomized block design was used in a 2×2 factorial scheme: two spacings (1.6 × 0.5 m and 1.0 × 0.5 m), with and without mulch, using five replications. In the end, the combination of spacing and presence and absence of mulch did not influence the height and diameter of the stem. However, it has influenced fresh matter: 8765.00 kg ha-1 (1.0 × 0.5 m, with mulch) and 6112.50 kg ha-1 (1.6 × 0.5 m, without mulch). The spacing 1.0 x 0.5 m was what provided higher dry matter (3052.14 kg ha-1). For the production of essential oil, the combination of spacing of 1.0 × 0.5 m, with mulch provided greater production (484.50 kg ha-1). Twenty-seven compounds were detected, of which 23 were identified, most of which were sesquiterpenes and monoterpenes. The α-pinene and the β-caryophyllene showed higher abundances in all samples, regardless of the treatment. The contents of α-humulene was sufficient to meet the requirements of the pharmaceutical industry. Thus, the alteration in soil spacing and mulch influences the production of essential oil and biomass, but it does not influence the relatives amount of the α-humulene and of the β-caryophyllene.

Organic fertilization affecting pests and production of Lippia sidoides Cham. (Verbenacea)

The objective of this paper was to study the effect of four levels of organic fertilization (0, 3, 6 and 9 kg m-2) to produce the essential oil of Lippia sidoides Cham. (Verbenacea) and its pests. A higher number of red mite Tetranychus sp. (Acari: Tetranychiidae) was observed on the abaxial face of the median and basal leaves of L. sidoides plants with eight weeks of age cultivated with 6 kg m-2 of organic fertilization. On the other hand, the smallest number of this mite was noted in control (0 kg m-2). L. sidoides cultivated with 6 kg m-2 of organic fertilization produced a greater quantity of essential oil. The highest number of mealy bug Phenacoccus sp. (Hemiptera: Pseudococcidae) was observed on the apical leaves (both leaf surfaces) of L. sidoides plants with nine and ten weeks of age cultivated with 3 kg m-2 of organic fertilization. No significant effect of the organic fertilization on Aphis gossypii Glover (Hemiptera: Aphididae) was detected. However, a greater number of this aphid and of its predator Scymnus sp. (Coleoptera: Coccinelidae) was observed on the abaxial face of the bottom leaves of L. sidoides plants with eight weeks of age. The dose of organic fertilization recommended for the production of essential oil of L. Sidoides is 6 kg m-2, however, one must pay attention to the fact this dosage favors the attack by Tetranychus sp.. And, when needed, pulverization must always be directed to the lower surface of the leaf.

NPK e flavonoides afetando populações de insetos em mudas de Dimorphandra mollis

The study evaluated the influence of different levels of nitrogen (N), phosphorus (P) and potassium (K), and flavonoids on the population of insects in Dimorphandra mollis Benth (Leguminosae) seedlings. The treatments associated with the highest level of attacks by Frankliniella schulzei (Trybon) (Thysanoptera: Thripidae) were 600 mg dm -3 of P and 50 mg dm -3 of K. The highest level of attacks by Coccidae occurred for 300 of P and 150 and 250 mg dm -3 of K. The last two treatments also exhibited the highest level of attacks by Pseudococcidae. On the other hand, the control exhibited higher levels of flavonoids and a lower level of insect attacks. We observed a small positive effect of N levels on attack by F. schulzei. The levels of N, P and K negatively affected the levels of flavonoids in the leaves of D. mollis. We detected no significant effects of flavonoid levels on the populations of Coccidae, Pseudoccocidae and F. schulzei. Higher numbers of Coccidae and Pseudococcidae were observed in the abaxial face of apical leaves. However, higher numbers of F. schulzei were observed on the adaxial face at lower heights in the canopy. The preferred treatment for the production of D. mollis seedlings is the control (without fertilization) because it showed higher flavonoid levels than other treatments and did not result in higher insect numbers.

NPK and flavonoids affecting insect populations in Dimorphandra mollis seedlings - doi: 10.4025/actasciagron.v34i1.11233

The study evaluated the influence of different levels of nitrogen (N), phosphorus (P) and potassium (K), and flavonoids on the population of insects in Dimorphandra mollis Benth (Leguminosae) seedlings. The treatments associated with the highest level of attacks by Frankliniella schulzei (Trybon) (Thysanoptera: Thripidae) were 600 mg dm -3 of P and 50 mg dm -3 of K. The highest level of attacks by Coccidae occurred for 300 of P and 150 and 250 mg dm -3 of K. The last two treatments also exhibited the highest level of attacks by Pseudococcidae. On the other hand, the control exhibited higher levels of flavonoids and a lower level of insect attacks. We observed a small positive effect of N levels on attack by F. schulzei. The levels of N, P and K negatively affected the levels of flavonoids in the leaves of D. mollis. We detected no significant effects of flavonoid levels on the populations of Coccidae, Pseudoccocidae and F. schulzei. Higher numbers of Coccidae and Pseudococcidae were observed in the abaxial face of apical leaves. However, higher numbers of F. schulzei were observed on the adaxial face at lower heights in the canopy. The preferred treatment for the production of D. mollis seedlings is the control (without fertilization) because it showed higher flavonoid levels than other treatments and did not result in higher insect numbers.