Urania Menkissoglu-Spiroudi

Synergistic and antagonistic interactions of terpenes against Meloidogyne incognita and the nematicidal activity of essential oils from seven plants indigenous to Greece.

BACKGROUND Biorational means for phytonematode control were studied within the context of an increasingly ecofriendly pest management global approach. The nematicidal activity and the chemical composition of essential oils (EOs) isolated from seven plants grown in Greece and ten selected compounds extracted from them against second-stage juveniles (J2) of Meloidogyne incognita (Kof. & White) Chitwood were evaluated using juvenile paralysis experiments. Additionally, synergistic and antagonistic interactions between nematicidal terpenes were studied using an effect addition model, with the comparison made at one concentration level. RESULTS The 96 h EC(50) values of Foeniculum vulgare Mill., Pimpinella anisum L., Eucalyptus meliodora A Cunn ex Schauer and Pistacia terebinthus L. were 231, 269, 807 and 1116 µg mL(-1) , respectively, in an immersion bioassay. Benzaldehyde (9 µg mL(-1) ) was the most toxic compound, followed by γ-eudesmol (50 µg mL(-1) ) and estragole (180 µg mL(-1) ), based on 96 h EC(50) values. The most potent terpene pairs between which synergistic actions were found, in decreasing order, were: trans-anethole/geraniol, trans-anethole/eugenol, carvacrol/eugenol and geraniol/carvacrol. CONCLUSION This is the first report on the activity of F. vulgare, P. anisum, E. meliodora and P. terebinthus, and additionally on synergistic/antagonistic nematicidal terpene interactions, against M. incognita, providing alternative methods for nematode control.

Novel biomixtures based on local Mediterranean lignocellulosic materials: evaluation for use in biobed systems.

The composition of biomixtures strongly affect the efficacy of biobeds. Typically, biomixture consists of peat (or compost), straw (STR) and topsoil (1:2:1 by volume). Straw guarantees a continuous supply of nutrients and high microbial activity. However, in south Europe other lignocellulosic materials including sunflower crop residues (SFR), olive leaves, grape stalks (GS), orange peels, corn cobs (CC) and spent mushroom substrate (SMS) are also readily available at no cost. Their potential utilization in biomixtures instead of STR was tested in pesticide degradation and adsorption studies. The microbial activity in these biomixtures was also assessed. The GS-biomixture was the most efficient in pesticide degradation, while CC- and SFR-biomixtures showed comparable degrading efficacy with the STR-biomixture. The SMS-biomixture was also highly efficient in degrading the pesticide mixture with degradation rates being correlated with the proportion of SMS in the biomixture. Microbial respiration was positively correlated with the degradation rates of metalaxyl, azoxystrobin and chlorpyrifos, compared to phenoloxidase which showed no correlation. Biomixtures containing alternative lignocellulosic materials showed a higher adsorption affinity for terbuthylazine and metribuzin compared to the STR-biomixture. We provide first evidence that STR can be substituted in biomixtures by other lignocellulosic materials which are readily available in south Europe.

Cytotoxic Tirucallane Triterpenoids from Melia azedarach Fruits

The phytochemical investigation of the dichloromethane-soluble part of the methanol extract obtained from the fruits of Melia azedarach afforded one new tirucallane-type triterpene, 3-α-tigloylmelianol (1) and three known tirucallanes, melianone (2), 21-β-acetoxy-melianone (3), and methyl kulonate (4). The structure of the isolated compounds was mainly determined by 1D and 2D NMR experiments as well as HPLC-Q-TOF mass spectrometry. The cytotoxicity of the isolated compounds toward the human lung adenocarcinoma epithelial cell line A549 was determined, while no activity was observed against the phytonematode Meloidogyne incognita.

Do Botanical Pesticides Alter the Structure of the Soil Microbial Community

The effects of synthetic pesticides on the soil microbial community have been thoroughly investigated in the past mostly by culture-dependent methods and only few recent studies have used culture-independent approaches for this purpose. However, it should be noted that most of these studies have been conducted in microcosms where the soil microbial community is exposed to unrealistic concentrations of the pesticides, providing an unrealistic exposure scheme for soil microorganism. On the other hand, little is known regarding the potential impact of botanical pesticides on the soil microbial community. Therefore, a laboratory study and a field study were conducted to investigate the effects of synthetic (metham sodium [MS], sodium tetrathiocarbonate [SoTe], and fosthiazate) and botanical pesticides (azadirachtin, quillaja, and pulverized Melia azedarach fruits [PMF]) on the soil microbial community using phospholipid fatty acids (PLFA) analysis. Principal component analysis (PCA) on the results of the laboratory study indicated that the application of PMF resulted in significant changes in the soil microbial community. This was obvious by the proportional increase in the abundance of fatty acids 18:1ω9cis, 18:1ω9trans, which are common in gram-negative bacteria and saprotrophic fungi, and 18:2ω6,9, which is a fungal indicator. This response was attributed to the release of copious amounts of organic carbon and nutrients in the soil by the PMF. On the other hand, MS inhibited fungi and gram-negative bacteria, while fosthiazate and the botanical pesticides quillaja and azadirachtin did not impose significant changes in the soil microbial community. Similar results were obtained by the field study where application of the fumigants MS and SoTe significantly altered the structure of the soil microbial community with the former having a more prominent effect. Fosthiazate imposed mild changes in the soil microbial community, whereas quillaja and azadirachtin again did not show a significant effect. Overall, botanical pesticides, at their recommended dose, did not alter the structure of the soil microbial community compared to synthetic nonfumigant and fumigant pesticides which induced significant changes.

Bacterial colonization of the phyllosphere of nineteen plant species and antimicrobial activity of their leaf secondary metabolites against leaf associated bacteria

Summary.The scope of this work was to examine whether leaf constitutive secondary metabolites play a role in determining bacterial colonization of the phyllosphere. To this aim, we surveyed nineteen native or cultivated plant species that share a common bacterial pool in a North Mediterranean area, and estimated the size of total and ice nucleation active (INA) bacterial populations on their leaves. Large differences in the colonization of their phyllosphere were found; the population size of epiphytic bacteria ranged from 7.5 × 102 to 1 × 106 CFU/g fresh weight, in eucalypt and celery, respectively. Species native in Mediterranean-type climate areas, particularly those belonging to the group of aromatic plants, are characterized by scarce presence of INA bacteria. The antibacterial activity of essential oils, surface phenolics and leaf tissue extracts was also estimated against the INA strains P. syringae and E. herbicola, isolated from two of these plant species. E. herbicola proved more sensitive than P. syringae. Of the species examined, oregano [Origanum vulgare L. subsp. hirtum (Link.) Ietswaart], an aromatic plant, had the highest antimicrobial activity, whereas six species showed no activity at all. Further experiments were performed with oregano and bean (Phaseolus vulgaris L.) that represent two extremes in their secondary metabolite content. Both plants were inoculated with P. syringae. By the end of incubation, the bacterial population on bean plants was about 100 times higher than that on oregano leaves. Scanning electron micrographs showed that bacterial growth on oregano leaves was confined to sites away from glandular hairs. Results from the bacterial colonization survey together with those from the toxicity tests showed that all species rich in antibacterial secondary metabolites harbored low leaf bacterial populations. These results provide substantial evidence that leaf secondary metabolites function as constitutive defense chemicals against microbial invasions. However, the fact that species with non- or moderately active leaf secondary metabolites are not always highly colonized suggests mediation of other unknown factors, the contribution of which requires further investigation.

Matrix effect in gas chromatographic determination of insecticides and fungicides in vegetables

A study of the matrix-induced effect was performed for 16 common pesticides, most frequently found in monitoring studies in tomato, pepper and cucumber, using a simple multiresidue method with gas chromatography (GC) and electron-capture (ECD) or nitrogen-phosphorus (NPD) detection, without a previous cleanup step. Anomalously high gas chromatography responses and subsequently very high recoveries for several pesticides in the extracts were obtained by a conventional calibration with pesticide solution in ethyl acetate. Sample matrix enhancement varied from little to no effect for some pesticides (e.g. chlorpyrifos, pirimicarb) to >200% in the case of certain susceptible pesticides (captan, procymidone, iprodione). Pronounced matrix effects were observed at low concentration levels of analyte for all the ECD-detected pesticides. The use of matrix-standards solutions was found to reduce the recoveries of most pesticides to the levels of 70–110% acceptable for residue analysis.

Nematicidal Activity of Mint Aqueous Extracts against the Root-Knot Nematode Meloidogyne incognita

The nematicidal activity and chemical characterization of aqueous extracts and essential oils of three mint species, namely, Mentha × piperita , Mentha spicata , and Mentha pulegium , were investigated. The phytochemical analysis of the essential oils was performed by means of GC-MS, whereas the aqueous extracts were analyzed by LC-MS. The most abundant terpenes were isomenthone, menthone, menthol, pulegone, and carvone, and the water extracts yielded mainly chlorogenic acid, salvianolic acid B, luteolin-7-O-rutinoside, and rosmarinic acid. The water extracts exhibited significant nematicidal activity against Meloidogyne incognita , and the EC50/72h values were calculated at 1005, 745, and 300 mg/L for M. × piperita, M. pulegium, and M. spicata, respectively. Only the essential oil from M. spicata showed a nematicidal activity with an EC50/72h of 358 mg/L. Interestingly, menthofuran and carvone showed EC50/48h values of 127 and 730 mg/L, respectively. On the other hand, salicylic acid, isolated in the aqueous extracts, exhibited EC50 values at 24 and 48 h of 298 ± 92 and 288 ± 79 mg/L, respectively.

New multiresidue method using solid-phase extraction and gas chromatography–micro-electron-capture detection for pesticide residues analysis in royal jelly

Royal jelly, one of the most important bee products, can be contaminated with pesticide and/or antibiotic residues resulting from treatments applied either inside beehives or in the agricultural environment. A new multiresidue method was developed and validated for analysis of nine pesticides in royal jelly. Solid-phase extraction RP-C(18) cartridges were used for sample purification and isolation of analytes. Final solution was analyzed with GC and micro-electron-capture detection. Four synthetic acaricides used by beekeepers (bromopropylate, coumaphos, malathion and tau-fluvalinate), and moreover one pyrethroid, two organochlorine, and two organophosphate insecticides were tested. Linearity is demonstrated for the range of 0.0025-1mgkg(-1), with correlation coefficients ranging from 0.99991 to 0.99846, depending on the analyte. Overall recovery rates from royal jelly blank samples spiked at five fortification levels ranged from 80.8% (lindane) to 91.3% (ethion), well above the range defined by the SANCO/10232/2006 and EC/675/2002 documents. The limit of quantification was <0.003-0.005 mg kg(-1) depending on the analyte, and the reporting level of the method, defined as the lowest recovery level, was 0.005 mg kg(-1).

Pesticides of Botanical Origin: a Promising Tool in Plant Protection

Future agricultural and rural development is, to a large extent, influenced by the rapidly increasing food demand of 2.5 billion people expected to swell the world population by 2020. Achieving food sufficiency in a sustainable manner is a major challenge for farmers, agro-industries, researchers and governments (Schillhorn van Veen, 1999). The intensification of agriculture to fulfil food needs has increased the number of insect pest species attacking different crops and as a result the annual production losses of the standing crops. In the past, synthetic pesticides have played a major role in crop protection programmes and have immensely benefited mankind. Nevertheless, their indiscriminate use has resulted in the development of resistance by pests (insects,weeds, etc), resurgence and outbreak of new pests, toxicity to non-target organisms and hazardous effects on the environment endangering the sustainability of ecosystems (Jeyasankar & Jesudasan, 2005). In the recent years the EU has employed a fundamental reform of the Common Agricultural Policy (CAP) highlighting the respect to the environmental, food safety and animal welfare standards, imposing farmlands’ cross-compliance with good agricultural and environmental conditions (Schillhorn van Veen, 1999). Due to environmental side effects and health concerns, many synthetic carbamate, organophosphate, and organophthalide pesticides have been banned (Council Directive 91/414/EEC) or are being under evaluation (Regulation 2009/1107/EC OL & Directive 2009/128/EC). On the other hand, industry does not equally sustain the economic cost of research and registration, of all pesticides’ chemical classes. The development of nematicides is rarely supported, even though in some cases, such as in the Netherlands, they represent more than 60% of the total pesticides used in agriculture (Chitwood, 2002). This is due to the fact that nematodes are a rather difficult target and the economic cost of research and registration is an enormous hurdle for a prospective new synthetic nematicide to overcome (Chitwood, 2002). As a result, currently there are only few nematicides left in use, and their limited number makes the repeated applications of the same formulation, inevitable. This fact has led to the enhancement nematicides biodegradation in soil (Qui et al., 2004 , Karpouzas et al., 2004, Arbeli & Fuentes, 2007) and the development of resistance in pests. (Meher et al., 2009) These two phenomena are expressed in field as lack of efficacy of the applied pesticides. All the above facts necessitate the urge for new and alternative pest control methods (Chitwood, 2002). An interesting way of searching for biorational pesticides is screening naturally occurring compounds in plants (Isman, 2006; 2008). Plants, as long-lived stationary organisms, must

Laboratory and field dissipation of penoxsulam, tricyclazole and profoxydim in rice paddy systems

Rice cultivation relies on pesticide applications to ensure high yields. However, the regular use of pesticides seriously affects the quality of neighboring surface water systems. Thus complete knowledge of the environmental fate and dissipation of pesticides in the paddy rice environment should become available. So far only a few studies have provided comprehensive assessment of the dissipation of pesticides under the submerged cultivation conditions followed in rice. Thus, laboratory and 2-year field studies were performed to assess the dissipation of two new generation rice herbicides (penoxsulam and profoxydim) and one of the most important rice fungicides (tricyclazole). A good agreement between laboratory and field experiments was observed with a faster dissipation of penoxsulam and tricyclazole under field conditions. Profoxydim was the least persistent chemical (DT50 soil<1d; DT50 water 0.5-1.2d), followed by penoxsulam which persisted for longer particularly in the water compartment (DT50water=3.8-5.9d). Tricyclazole was the most persistent pesticide, especially in the soil compartment with DT50 values of 44.5-84.6 (field) and 197d (laboratory). These results could be utilized for the assessment of the environmental risk associated with the use of those pesticides in rice cultivation and the determination of potential mitigation measures for minimizing the risk for contamination of neighboring natural water resources.