Effects of some plant extracts on larval hatch of the root-knot nematode,Meloidogyne incognita

Abstract

The inhibitory effect of water extract of seed, leaf and bark of five plants, viz., Tamarindus indica, Cassia siamea, Isoberlinia doka, Dolnix regia and Cassia sieberiana was evaluated on larval hatch of Meloidogyne incognita in the laboratory. All the plant parts inhibited larval hatch of M. incoginta Percentage inhibition was higher in the seeds followed by the leaves and bark. Degree of inhibition observed, was directly related to the concentration of the extract. The standard suspensions inhibited hatching by about 97% while dilutions of S/100 inhibited larval hatch by 3%. Nematicidal activity of the plant parts of the five plants showed that C. siamea was the most effective followed by C. sieberiana, I. doka, T. indica and D. regia.     

Screening of antifungal activity of various plant leaves extracts from Indian plants

The present study was designated to evaluate the antifungal activity and to root out the antifungal plant leaf extracts from this Indian folk-flore. The in vitro antifungal assay was performed by agar diffusion test and minimum inhibitory concentration (MIC) for hexane, ethyl acetate, methanol and distilled water plant leaf extracts. Extraction of 17 different plant leaves was carried out in different solvents such as hexane, ethyl acetate, methanol and distilled water. Among them extractive yield of methanol was maximum than the rest of the three solvents. These extracts were screened for their antifungal activity against nine different fungi. Among these ethyl acetate extracts of Adhatoda vasica, Ocimum sanctum and Holoptelea integrifolia exhibited maximum antifungal activity against Alternaria sp., Aspergillus parasi, Aspergillus nidulans, Trichoderma harzianum and Aspergillus flavus with MIC of 80, 40 and 20 ppm against Aspergillus nidulans and Alternaria sp. Ethyl acetate extracts showed promising antifungal activity against Adhatoda vasica, Ocimum sanctum and Holoptelea integrifolia against Aspergillus nidulans, and Alternaria sp. might be applicable as fungicide against fungal plants disease.     

Inhibitory effect of botanical extracts against Alternaria alternata of aloe vera dry rot

Aloe vera dry rot caused by Alternaria alternata, is one of the most serious fungal diseases affecting the commercial cultivation of aloe vera in North India. Control of this disease through chemical is quite expensive and not ecofriendly. The plant extracts as biopesticdes act as a vital components for the management of this disease. Evaluation of some plant extracts was carried out against A. alternata in laboratory conditions. The extracts were prepared at 5% and 10% concentration and were evaluated through inhibition in radial growth (food poison technique) and spores (conidia) germination (hanging drop technique) against A. alternata. Neem leaf extract gave 58.6% inhibition in radial growth and 56.5% in spore germination at 10% concentration followed by Ocimum sanctum which was found effective and gave 54.7% inhibition in radial growth and 50.4% in spore germination over control.     

Efficacy of some plant extracts in the management of cercospora leaf spot of groundnut in the Sudan savanna of Nigeria

Field trials were conducted to evaluate the efficacy of neem seed, garlic clove, onion bulb, ginger rhizome and pawpaw leaf extracts applied as foliar spray in controlling cercospora leaf spot of groundnut in the Sudan savanna of Nigeria during the 2002 and 2003 cropping seasons. Ridomil was used as a positive check while the control was left untreated. Three spray regimes (once, twice and thrice) were evaluated. A strip plot design with three replications was used in setting up the experiments. Ex-Dakar, a cercospora leaf spot susceptible Spanish Valencia groundnut variety, was used as planting material. All the plant extracts reduced the incidence and severity of cercospora leaf spot in both seasons compared to the untreated crops. However, neem seed and garlic clove extracts significantly reduced the incidence and severity of the disease compared to the other plant extracts. Ridomil was more effective in controlling the disease than the plant extracts. Three sprays with the plant extracts gave better control of the disease than one or two sprays in the season. The highest seed yield of 3115 kg/ha and 3311 kg/ha in 2002 and 2003, respectively, were obtained with neem seed extract treatment while the lowest seed yield of 2134 kg/ha and 2334 kg/ha in 2002 and 2003, respectively, were recorded from the untreated crops. Also the highest seed yield of 3124 kg/ha and 3418 kg/ha in 2002 and 2003, respectively were obtained following three sprays compared to 2523 kg/ha and 2641 kg/ha for one spray in 2002 and 2003, respectively and 2840 kg/ha and 3085 kg/ha for two sprays in 2002 and 2003, respectively. The highest haulm yield of 4121 kg/ha and 4089 kg/ha in 2002 and 2003, respectively were also obtained following treatment with neem seed extract. The lowest haulm yield of 2951 kg/ha and 3045 kg/ha in 2002 and 2003 respectively, were recorded from the control. Three sprays gave higher haulm yield (4265 kg/ha and 4279 kg/ha in 2002 and 2003, respectively) than one and two sprays in the season. Neem seed extract could therefore be used to control cercospora leaf spot and to improve groundnut production in the Sudan savanna of Nigeria.     

Grape seed proanthocyanidin extracts prevent high glucose-induced endothelia dysfunction via PKC and NF-κB inhibition

In our study, it has been detected in vivo and in vitro that GSPE reversed high glucose-induced the increase of ICAM-1 and VCAM-1. It is shown that by western blotting detection, GSPE significantly inhibited the activation of NF-κB induced by high glucose while there was significant decrease of the expression of PKC with GSPE intervention. By adding the NF-κB blocker PDTC and the PKC inhibitor peptide 19–31(10^?6 M), no significant difference was found in the levels of VCAM-1 and ICAM-1 among GSPE group, the PKC inhibitor peptide 19–31-added GSPE group and the PDTC-added GSPE group. So the conclusion could be drawn that PKC inhibition must be involved in GSPE decreasing the level of ICAM-1 and VCAM-1.We proved for the first time that GSPE prevented high glucose-induced the increase of ICAM-1 and VCAM-1 by PKC and NF-κB inhibition. These findings show a novel mechanism of the action GSPE preventing endothelial dysfunction, which may have clinical application values.     

Free radical scavenging activity from different extracts of leaves of Bauhinia vahlii Wight & Arn.

The objectives of this study were to determine phenolic content and antioxidant activities of chloroform, acetone, methanol and hot water extracts of Bauhinia vahlii leaves. The hot water extract afforded the highest yield (6.3%) while the lowest yield was obtained from the chloroform extract (2.1%). The methanol extract contains higher levels of total phenolics (48.7 ± 0.7 g GAE/100 g extract), tannins (21.7 ± 0.7 g GAE/100 g extract) and flavonoids (10.3 ± 0.2 RE/100 g extract). The extracts were subjected to assess their antioxidant potential using various in vitro systems such as DPPH, ABTS⁺, FRAP, OH, β-carotene linoleic acid bleaching system, phosphomolybdenum reduction and Fe²⁺ chelation. It is concluded that the methanolic extract of B. vahlii leaves have strong antioxidant potential. Further study is necessary for isolation and characterization of the active antioxidants, which may serve as a potential source of natural antioxidants.     

Investigating the bioactivity of cells and cell-free extracts of Streptomyces griseus towards Fusarium oxysporum f. sp. cubense race 4

The antifungal activity of viable cells of Streptomyces griseus (St 4) and its cell-free extracts were investigated against the pathogenic Fusarium oxysporum f. sp. cubense race 4 (FOC race 4), causal agent of wilt disease in bananas. Results from in vitro and soil assays showed cells and cell-free extracts of S. griseus were able to inhibit FOC race 4 with varying degree of success. Antifungal activity was attributed to chitinase and β-1,3-glucanase, detected in both cells and cell-free extracts, which caused lysis of fungal cell wall and inhibited sporulation. Interestingly, β-1,3-glucanase and chitinase activities were significantly higher in cell-free extracts compared to cells, with 8.30 and 5.43 against 7.96 and 4.95 U mL⁻¹, respectively. Application to soil however, showed inoculation using S. griseus cells were more effective in suppressing growth of FOC race 4 than crude extracts, with 6 log₁₀ CFU of FOC race 4 g⁻¹ soil enumerated compared to 7 log₁₀ CFU of FOC race 4 g⁻¹ soil after 20 days. To summarize, this study has shown that cell-free extracts of S. griseus have antifungal properties but may not be suitable for soil application in its current form (liquid suspension). Further investigations on bioformulation may address this limitation.     

Insecticidal effect of plant extracts on common pistachio psylla,Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Aphalaridae)

The common pistachio psylla, Agonoscena pistaciae (Hemiptera: Aphalaridae) is one of the most detrimental pests to pistachio trees. Nowadays various pesticides are used to control the common pistachio psylla, but extensive pesticide spraying against this pest over a period of several years has overpowered its natural enemies. The plant’s byproducts come as an alternative ecologically more compatible in substitution to the synthetic insecticides. This work aims to evaluate the insecticidal potential of herbal extracts of fruit peels of Citrus sinensis and Citrus reticulata, seeds of C. sinensis and Rubia tinctorum, and leaves of Lawsonia inermis against common pistachio psylla. Five concentration 40, 47, 56, 67 and 80 µl/ml, of these plant extracts were sprayed on the fifth instar nymphs of common pistachio psylla by Potter Spray Tower under laboratory conditions (26?±?2?°C, 60–70% RH and a photoperiod of 16L: 8D h). Results showed significant differences among the treatments of the plant extracts and between the concentrations. The LC₅₀ values of C. sinensis peels, C. reticulata peels, C. sinensis seeds, R. tinctorum seeds and L. inermis leaves were 62.04, 38.84, 43.60, 59.01 and 33.99 µl/ml, respectively. Also, all extracts showed the greatest mortality effect in 80 µl/ml concentration. According to these results, these plant extracts may use as herbal pesticides chemical control programme of common pistachio psylla.     

Control of Brevicoryne brassicae (Hemiptera: Aphididae) with extracts of Agave americana var. Marginata Trel. in Brassica oleracea crops

Alternative methods of pest control can and should be encouraged, especially those that consider the reality of smallholder family farmers. Here, we evaluated the potential of Agave americana (agave) extracts for the control of the aphid Brevicoryne brassicae in cabbage (Brassica oleracea L. var acephala) in the field and laboratory. The field experiments consisted of the evaluation of the proportion of dead aphids on cabbage plants after application of agave extracts. In the field, agave mixed with cow milk caused mortality above 80% and was the most effective extract. Agave mixed with water and agave mixed with ethanol elicited mortality above 60%. In the laboratory, we evaluated the mortality of aphids after the application of different concentrations of aqueous agave extracts; the commercial insecticide deltamethrin was included as positive control. Evaluation took place at 3, 6, 12, 24, 48 and 72 hr after applying the treatment. As expected, deltamethrin was the most effective treatment. However, agave extract at concentrations of 0.750 and 0.500 g/mL caused >70% mortality 3 hr after application. We conclude that A. americana extracts decreased aphid populations and is a promising alternative to the commercial insecticide against aphids in cabbage.