Paulo Alves Wanderley

CHEMICAL COMPOSITION AND ANTIFUNGAL ACTIVITY OF HYPTIS SUAVEOLENS (L.) POIT LEAVES ESSENTIAL OIL AGAINST ASPERGILLUS SPECIES

This study aimed to identify the constituents of the essential oil from Hyptis suaveolens (L.) leaves using a Gas Chromatograph - Mass Spectrometer and assess its inhibitory effect on some potentially pathogenic Aspergilli (A. flavus, A. parasiticus, A. ochraceus, A. fumigatus and A. niger). Eucaliptol (47.64 %) was the most abundant component in the oil, followed for gama-ellemene (8.15 %), beta-pynene (6.55 %), (+)-3-carene (5.16 %), trans-beta-cariophyllene (4.69 %) and germacrene (4.86 %). The essential oil revealed an interesting anti-Aspergillus property characterized by a Minimum Inhibitory Concentration and Minimum Fungicidal Concentration of 40 and 80 µL/mL, respectively. The oil at 80 and 40 µL/mL strongly inhibited the mycelial growth of A. fumigatus and A. parasiticus along 14 days. In addition, at 10 and 20 µL/mL the oil was able to cause morphological changes in A. flavus as decreased conidiation, leakage of cytoplasm, loss of pigmentation and disrupted cell structure suggesting fungal wall degeneration. These findings showed the interesting anti-Aspergillus property of H. suaveolens leaves essential oil supporting its possible rational use as alternative source of new antifungal compounds to be applied in the aspergillosis treatment.

Antifungal activity of Cymbopogon winterianus jowitt ex bor against Candida albicans

Candida albicans is an opportunistic yeast and a member of the normal human flora that commonly causes infections in patients with any type of deficiency of the immune system. The essential oils have been tested for antimycotic activity and pose much potential as antifungal agents. This work investigated the activity of the essential oil of Cymbopogon winterianus against C. albicans by MIC, MFC and time-kill methods. The essential oil (EO) was obtained by hydrodistillation using a Clevenger-type apparatus. It was tested fifteen strains of C. albicans. The MIC was determined by the microdilution method and the MFC was determined when an aliquot of the broth microdilution was cultivated in SDA medium. The phytochemical analysis of EO showed presence of citronellal (23,59%), geraniol (18,81%) and citronellol (11,74%). The EO showed antifungal activity, and the concentrations 625 µg/mL and 1250 µg/mL inhibited the growth of all strains tested and it was fungicidal, respectively. The antimicrobial activity of various concentrations of EO was analyzed over time, it was found concentration-dependent antifungal activity, whose behavior was similar to amphotericin B and nystatin.

Growth inhibition and morphological alterations of Trichophyton rubrum induced by essential oil from Cymbopogon winterianus Jowitt ex Bor

Trichophyton rubrum is one of the most common fungi causer of dermatophytosis, mycosis that affect humans and animals around the world. Researches aiming new products with antifungal activity become necessary to overcome difficulties on treatment of these infections. Accordingly, this study aimed to investigate the antifungal activity of essential oil from Cymbopogon winterianus against the dermatophyte T. rubrum. The antifungal screening was performed by solid medium diffusion method with 16 T. rubrum strains, minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) were determined using the microdilution method. The effects on mycelial dry weight and morphology were also observed. Screening showed essential oil in natura inhibited all the tested strains, with inhibition zones between 24-28 mm diameter. MIC50 and MIC90 values of the essential oil were 312 µg/mL for nearly all the essayed strains (93.75 %) while the MFC50 and MFC90 values were about eight times higher than MIC for all tested strains. All tested essential oil concentrations managed to inhibit strongly the mycelium development. Main morphological changes on the fungal strains observed under light microscopy, which were provided by the essential oil include loss of conidiation, alterations concerning form and pigmentation of hyphae. In the oil presence, colonies showed folds, cream color and slightly darker than the control, pigment production was absent on the reverse and with evident folds. It is concluded that C. winterianus essential oil showed activity against T. rubrum. Therefore, it could be known as potential antifungal compound especially for protection against dermatophytosis.Trichophyton rubrum is one of the most common fungi causer of dermatophytosis, mycosis that affect humans and animals around the world. Researches aiming new products with antifungal activity become necessary to overcome difficulties on treatment of these infections. Accordingly, this study aimed to investigate the antifungal activity of essential oil from Cymbopogon winterianus against the dermatophyte T. rubrum. The antifungal screening was performed by solid medium diffusion method with 16 T. rubrum strains, minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) were determined using the microdilution method. The effects on mycelial dry weight and morphology were also observed. Screening showed essential oil in natura inhibited all the tested strains, with inhibition zones between 24-28 mm diameter. MIC50 and MIC90 values of the essential oil were 312 μg/mL for nearly all the essayed strains (93.75 %) while the MFC50 and MFC90 values were about eight times higher than MIC for all tested strains. All tested essential oil concentrations managed to inhibit strongly the mycelium development. Main morphological changes on the fungal strains observed under light microscopy, which were provided by the essential oil include loss of conidiation, alterations concerning form and pigmentation of hyphae. In the oil presence, colonies showed folds, cream color and slightly darker than the control, pigment production was absent on the reverse and with evident folds. It is concluded that C. winterianus essential oil showed activity against T. rubrum. Therefore, it could be known as potential antifungal compound especially for protection against dermatophytosis.

The effect of essential oils of sweet fennel and pignut on mortality and learning in africanized honeybees (Apis mellifera L.) (Hymenoptera: Apidae)

It was recently discovered that exposure to small concentrations of the essential oils of sweet fennel (Foeniculum vulgare Mill) or pignut [Hyptis suaveolens (L.) Poit] can be used to control aphids. What is not known is whether these oils also influence honeybee behavior. Experiments using both harnessed and free-flying foragers at concentrations used to control aphids showed that bees readily associated the odors with a reward, discriminated between them, and were not repelled. Honeybees, however, would not consume the oils when mixed with sucrose to create an unconditioned stimulus. An experiment in which harnessed bees consumed various concentrations showed that concentrations greater than 50% were detrimental. The experiments reported here provide further evidence supporting the use of conditioning techniques to evaluate the use of essential oils on honey bee behavior.

Thermal requirements and development ofBracon vulgaris, a parasitoid of the cotton boll weevil

The development ofBracon vulgaris Ashmead (Hymenoptera: Braconidae), parasitoid of the cotton boll weevilAnthonomus grandis Boheman (Coleoptera: Curculionidae), was studied at constant temperatures of 18, 20, 23, 25, 28, 30, 33, 35 and 38°C, 70±10% r.h. and 14:10 L:D period. The period from egg to adult ofB. vulgaris varied from 8.6 (35°C) to 32.9 days (18°C). The eggs of this parasitoid became desiccated and did not hatch at 38°C. The lower development threshold (LDT) and thermal constants for development varied withB. vulgaris instar, but they were similar for males and females. The duration of the 1st, 2nd, 3rd and 4thB. vulgaris instars required, respectively, 9.36 degree-days above one LDT=12.27°C, 13.48 degree-days above one LDT=6.83°C, 11.65 degree-days above one LDT=9.41°C, and 12.82 degree-days above one LDT=10.78°C.B. vulgaris has physiological adaptations to different threshold temperatures and it shows high potential to be used againstA. grandis in cotton crops.

Temperature-dependent development rates of Bracon vulgaris, a parasitoid of boll weevil

The duration of development of Bracon vulgaris Ashmead, parasitoid of the boll weevil Anthonomus grandis Boheman, was determined at nine constant temperatures between 18°C and 38°C. Nonlinear regression analysis was used to test the fit of temperature-dependent development rates to the Sharpe and DeMichele and Lactin et al. models. At the highest tested temperature (38°C) all the parasitoid eggs died before hatching and no evidence of development was observed. The high values of R2 for the models of Sharpe and DeMichele (0.8432 to 0.9834), and Lactin et al. (0.9071 to 0.9795) indicated that these models are suitable to estimate the development rate of B. vulgaris as a function of temperature. B. vulgaris showed tolerance to high temperature which is represented by the high value of HH (change in enthalpy associated with high-temperature inactivation of the enzyme) for the prepupa stage of this insect obtained with the Sharpe and DeMichele model. According to that model, B. vulgaris exhibits thermal stress at 35.7°C, which indicates that maximum thermal stress estimated by this model was close to the real one.

Resistência de cultivares de batata-doce a Euscepes postfasciatus Fairmaire (Coleoptera: Curculionidae)

Universidade Federal da Paraiba Centro de Formacao de Tecnologosa Departamento de Agropecuaria

Effect of temperature on the reproduction of Bracon vulgaris Ashmead (Hymenoptera: Braconidae), a parasitoid of the cotton boll weevil

Estudamos os efeitos da temperatura na reproducao de Bracon vulgaris Ashmead, ectoparasitoide do bicudo-do-algodoeiro, Anthonomus grandis Boheman, em câmaras climatizadas, em temperaturas constantes de 20, 25 and 30oC, umidade relativa do ar de 70 ± 10% e fotofase de 14 h. As femeas do parasitoide produziram mais ovos a 25oC (124,65 ovos) do que aquelas expostas a 20 (43,40 ovos) e a 30oC (49,60 ovos). O numero medio de larvas parasitadas por femea de B. vulgaris a 25oC(71,75 larvas) foi maior do que a 20oC (31,40 larvas) e 30oC (25,15 larvas). As taxas diarias de aumento (rm) foram -0,007 a 20oC, 0,07 a 25oC e 0,03 a 30oC, indicando que a temperatura de 25oC produziu aumento de 1100 e 133% no valor de rm em relacao as temperaturas de 20 e 30oC, respectivamente. Nos programas de controle biologico do bicudo-do-algodoeiro, usando liberacoes inoculativas deve-se utilizar femeas adultasde B. vulgaris com aproximadamente 5 dias (a 25 ou 30oC) ou 20 dias de idade (a 20oC); quando usando liberacoes inundativas, utilizar femeas adultas de B. vulgaris , com idade entre 11 e 31 dias (a 20oC); 9 e 29 dias (a 25oC) ou 3 e 14 dias (a 30oC).

EFFECT OF TEMPERATURE ON THE REPRODUCTION OF BRACON VULGARIS ASHMEAD (HYMENOPTERA: BRACONIDAE), A PARASITOID OF THE COTTON BOLL WEEVIL'

ABSTRACT: This research studied the effect of temperature on the reproduction of Bracon vulgaris Ashmead (Hymenoptera: Braconidae), an ectoparasitoid of the cotton boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae), in climatic chambers, using constant temperatures of 20, 25, and 30°C, relative air humidity of 70 ± 10% and a photophase of 14 h. Females of the parasitoid produced a greater number of eggs when exposed to 25°C (124.65 eggs) in relation to those exposed to 20 (43.40 eggs) and 30°C (49.60 eggs). The mean number of parasitized larvae per female of B. vulgaris at 25°C (71.75) was greater than at 20°C (31.40) and 30°C (25.15). The daily intrinsic rates of increase (rm) were -0.007 at 20°C, 0.07 at 25°C and 0.03 at 30°C, revealing that the temperature of 25°C produced increases of 1,100 and 133% in the value rm in relation to the temperatures of 20 and 30°C, respectively. In programs of biological control of the boll weevil using innoculative releases, adult females of B. vulgaris with approximately five (at 25 or 30°C) or 20 day old (at 20°C) should be used; when using innundative releases, adult females of B. vulgaris, with ages between 11 and 31; 9 and 29 or 3 and 14 days of age, respectively, at 20, 25, or 30°C should be used.

Efeito de quatro tipos de mel na longevidade e reprodução de Catolaccus grandis (Hymenoptera:pteromalidae)

O trabalho teve como objetivo conhecer o melhor tipo de mel em relacao a longevidade e fertilidade do parasitoide do bicudo-do-algodoeiro Catolaccus grandis. Adultos recem-emergidos foram transferidos para recipientes plasticos de 500mL, adaptados com tubo para fornecer agua e umidade para os insetos. Um casal do parasitoide foi mantido em cada recipiente em câmara climatizada a 25±1°C, UR = 70±10% e fotoperiodo de 14h. O trabalho constou de 4 tratamentos: mel de flor de laranjeira; mel de flores de plantas silvestres; mel de cana-de-acucar (todos produzidos por Apis mellifera) e mel de flores silvestres produzido por abelha Jatai (Tetragonistica angustula), com 15 repeticoes cada. Adultos recem-emergidos do parasitoide receberam cinco larvas de Euscepes postfasciatus encapsuladas em parafilm. Tres goticulas de mel foram colocadas sobre o parafilm. Calculou-se a longevidade de machos e femeas, numero de ovos dia-1 femea-1 e numero total de ovos femea-1 e construiram-se as tabelas de fertilidade. As melhores dietas para alimentar adultos de C. grandis foram o mel silvestre e o de laranjeira. A melhor fecundidade foi observada na dieta de mel de laranjeira (101,60 ovos femea-1) e os melhores resultados para aumento reprodutivo e populacional deste parasitoide foram obtidos com mel de laranja e com mel silvestre.