EVALUATION OF SUBLETHAL EFFECTS OF Ipomoea cairica LINN. EXTRACT ON LIFE HISTORY TRAITS OF DENGUE VECTORS

Plant derived insecticides have considerable potential for mosquito control because these products are safer than conventional insecticides. This study aimed to investigate sublethal activities of Ipomoea carica or railway creeper crude acethonilic extract against life history trait of dengue vectors, Aedes albopictus and Aedes aegypti. The late third instar larvae of Ae. albopictus and Ae. aegypti were exposed to a sublethal dose at LC50 and larvae that survived were further cultured. Overall, Ipomea cairica crude extracts affected the whole life history of both Aedes species. The study demonstrated significantly lower egg production (fecundity) and eggs hatchability (fertility) in Ae. albopictus. The sublethal dose of crude extracts reduced significantly the width of larval head capsule and the wing length of both sexes in both Aedes species. The significance of sublethal effects of I. cairica against Aedes mosquitoes was an additional hallmark to demonstrate further activity of this plant despite its direct toxicity to the larvae. The reduced reproductive capacity as well as morphological and physiological anomalies are some of the effects that make I. cairica a potential candidate to be used as a new plant-based insecticide to control dengue vectors

Chemical composition and larvicidal activity of essential oils from six Apiaceae family taxa against the West Nile virus vector Culex pipiens

The chemical compositions of essential oils (EOs) obtained from six different taxa of the Apiaceae family, Apioideae subfamily, belonging to three tribes and six different genuses were determined by gas chromatography and gas chromatography-mass spectrometry analyses. All examined plants grow naturally in different habitats throughout Greece. The insecticidal properties of these EOs were evaluated against Culex pipiens L. larvae of third and early fourth instars in order to delineate the relationship between the EOs phytochemical content and larvicidal activity. The analytical data indicated that the EOs are mainly consisted of monoterpenes, mostly cyclic and only occasionally aliphatic. The larvicidal bioassay results indicated that the oil of Oenanthe pimpinelloides L., which contains mainly nonoxygenated monoterpenes, possesses the highest activity against Cx. pipiens larvae, displaying a LC(50) value of 40.26 mg/L. On the contrary, the EO of Elaeoselinum asclepium (L.) Bertol, which is consisted of pinenes and oxygenated monoterpenes, was the less active (LC(50) value of 96.96 mg/L). These results reveal that the nonoxygenated monoterpenes possess potent insecticidal activities against Cx. pipiens L. and the EO of O. pimpinelloides L. represents an inexpensive source of natural pest control mixture.Parasitol Re

Characterization of the essential oil volatiles of Satureja thymbra and Satureja parnassica: Influence of harvesting time and antimicrobial activity

Seasonal variation in chemical composition of essential oils obtained from Satureja parnassica subsp. parnassica Heldr. & Sart ex Boiss. and Satureja thymbra L. was determined by GC and GC-MS analysis. The in vitro antibacterial activities of these essential oils were evaluated at two different initial levels against two common foodborne bacteria. Their minimum inhibitory concentration (MIC) and noninhibitory concentration (NIC) values were determined via an innovative automated technique, which was applied on a Malthus apparatus combining the conductance measurements with the common dilution method. The essential oil concentration fluctuated greatly during the period examined and established that the Satureja oils obtained during the flowering period were the most potent, exhibiting the lowest MIC values and retaining remarkable bactericidal properties. Thus, they represent an inexpensive source of natural antibacterial substances that exhibit potential for use in food systems to prevent the growth of foodborne bacteria and to extend the shelf life of the processed food. © 2006 American Chemical Society

Essential oils of indigenous in Greece six Juniperus taxa : Chemical composition and larvicidal activity against the West Nile virus vector Culex pipiens

The chemical composition of 14 essential oils (EOs), obtained from various parts (leaves, fruits, wood) of the six indigenous in Greece Juniperus family taxa, was determined by GC and GC/MS analysis. The insecticidal properties of these EOs were evaluated against Culex pipiens L. larvae of 3rd and early 4th instars, in order to delineate the relationship between the phytochemical content of the EOs and their larvicidal activities. The analytical data indicated that the EOs mainly consisted of monoterpenes, mostly cyclic and only occasionally aliphatic, and to a lesser percent, of diterpenes. The larvicidal bioassays against C. pipiens larvae revealed that the most active EO was derived from the wood of Juniperus drupacea and contains mainly non-oxygenated monoterpenes and a significant amount of diterpenes, displaying the highest chemodiversity. Its initial LC(50) value was 26.47 mg L(-1). On the contrary, the EO isolated from J. phoenicea berries, which consisted of monoterpenes (non-oxygenated, cyclic), was the less active displaying an LC(50) value of 96.69 mg L(-1). In respect to the contained phytochemicals, myrcene was assayed as the most toxic, displaying an LC(50) value of 33.83 mg L(-1), while the four isomers of pinene abundant in all EOs were less active exhibiting LC(50) values ranging from 70.40 to 94.88 mg L(-1). Results herein reveal that the EOs isolated from the studied Juniperus family taxa represent an inexpensive source of natural mosquito control mixtures.Parasitol Re

Insecticidal Efficacy of Silica Gel With Juniperus oxycedrus ssp oxycedrus (Pinales: Cupressaceae) Essential Oil Against Sitophilus oryzae (Coleoptera: Curculionidae) and Tribolium confusum (Coleoptera: Tenebrionidae)

Laboratory bioassays were carried out to evaluate the effect of silica gel enhanced with the essential oil (EO) of Juniperus oxycedrus L. ssp. oxycedrus (Pinales: Cupressaceae) (derived from berry specimens from Greece) against adults of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae). For that purpose, a dry mixture consisting of 500 mg of silica gel that had absorbed 2.18 mg of EO (total weight: 502.18 mg) was tested at three doses; 0.125, 0.250, and 0.5 g/kg of wheat, corresponding to 125, 250, and 500 ppm, respectively, and silica gel alone at 0.5 g/kg of wheat corresponding to 500 ppm, at different exposure intervals (24 and 48 h and 7 and 14 d for S. oryzae; 24 and 48 h and 7, 14, and 21 d for T. confusum). The chemical content of the specific EO was determined by gas chromatography (GC)-mass spectrometry (MS) analyses indicating the presence of 31 constituents with myrcene and germacrene-D being the predominant compounds. The bioactivity results for S. oryzae indicated that 48 h of exposure in wheat resulted in an 82% mortality for treatment with 500 ppm of the enhanced silica gel. For 7 d of exposure, 100 and 98% of S. oryzae adults died when they were treated with 500 and 250 ppm of enhanced silica gel, respectively. At 14 d of exposure, all adults died both at 250 and 500 ppm of enhanced silica gel. At 48 h, 7 and 14 d of exposure significantly less S. oryzae adults died in wheat treated with silica gel alone than at 250 or 500 ppm of enhanced silica gel. In the case of T. confusum, at 7 d of exposure, mortality in wheat treated with silica gel only was significantly higher in comparison to the other treatments. At the 14 d of exposure mortality in wheat treated with 500 ppm of silica gel alone was significantly higher than 125 and 250 ppm of the enhanced silica gel. Similar trends were also noted at 21 d of exposure, indicating that there is no enhancement effect from the addition of the EO. Results herein suggest that the simultaneous use of silica gel and J. oxycedrus ssp. oxycedrus EO enhances significantly its activity against S. oryzae

Correlation between Chemical Composition of Greek Essential Oils and their Antibacterial Activity against Food-borne Pathogens

The compositions of forty-nine essential oils obtained from plants growing in areas of biodiversity in Greece were determined by means of gas chromatography and gas chromatography–mass spectrometry. The in vitro antibacterial activities of the oils were evaluated against a panel of five common food-borne bacteria ( Escherichia coli 0157:H7 NCTC 12900, Salmonella Enteritidis PT4, Staphylococcus aureus ATCC 6538, Listeria monocytogenes Scott A and Bacillus cereus FSS 134). Monoterpene hydrocarbons, phenolic monoterpenes and alcohols were the major constituents of the oils, but their concentrations varied greatly between the samples examined. The essential oils obtained from the species endemic to Greece ( Satureja and Origanum) had the most potent bactericidal properties. The chemical composition data were statistically processed through Principal Component Analysis (PCA) and correlated with the antibacterial activities, allowing a rough estimation of the potential of the essential oils antibacterial activity. </jats:p