Chemical composition of Artemesia herba-alba essential oil and its larvicidal and pupicidal effects against Culex pipiens (Diptera; Culicidae)

Artemisia herba-alba Asso (A. herba-alba) (Asteraceae) is widely used in herbal medicine as it is a mine of natural molecules such as davanone, which is an interesting product on the international market. The present research proposes a method for controlling the late larval (L4) and pupal stages of Culex pipiens based on the essential oil of A. herba-alba. The aerial part of this plant was extracted by hydrodistillation and then analyzed by gas chromatography coupled with mass spectrometry (CPG/SM) to determine its chemical composition. Three concentrations (1, 5 and 10 μl/ml) were prepared and directly tested on larvae (L4) and pupae under laboratory conditions to measure LC50, LC90, LT50, and LT90 values. The yield obtained in this study was 1.5%. Further, the analysis showed that the oil of A. herba-alba is a davanone chemotype that consists mainly of davanone (48.8%). The efficiency of this essential oil for toxicological parameters (LC50 and LC90) were 3.278 μl/ml and 7.573 μl/ml for larvae, and 1.213 μl/ml and 2.288 μl/ml for pupae. This study indicates that the essential oil of A. herba-alba has toxic properties for Cx. pipiens larvae and pupae. These results are encouraging and open up exciting and promising horizons for its application in the production of bioinsecticides

CHEMICAL CHARACTERIZATION of Foeniculum vulgare MILL ESSENTIAL OIL COMPOSITION AND ITS TOXICOLOGICAL EFFECTS AGAINST MOSQUITO: Aedes caspius (PALLAS, 1771) SPECIES

In this study, the essential oil (EO) of the aerial parts of Foeniculum vulgare Mill (Umbelliferae: Apiaceae) was extracted by hydro-distillation and subsequently, its chemical composition was analyzed using gas chromatography (GC) and the profile was identified by gas chromatography-mass spectrometry (MS). Then, its larvicidal potential was evaluated against the larvae of Aedes caspius (Pallas, 1771). Using the CPG-MS analyses fourteen volatile compounds representing 99.22% of the essential oil were identified; namely are: Camphor (38.2%), Fenchone (28.24%) and o-Cymene (11.44%) which were predominant in the EO of F.vulgare. The toxicity of the EO was evaluated, after 24h of exposure time, against the fourth instar larvae of Aedes caspius and the sublethal and lethal concentrations, LC25, LC50 and LC90 values were estimated with their confidence limits and their values are 27.65, 37.76 and 70.40 µl respectively. The obtained bioassay results showed that F. vulgare EO exhibited a toxic effect against Ae. caspius larvae with a dose-response relationship. Based on the results of the toxicity of F. vulgare EO, it can be concluded that, the present aromatic plant species showed a significant toxicological effect and could be used as a promising alternative for the mosquito control. This result opens interesting perspectives for its application in the production of a new source of various larvicidal active compounds for controlling mosquito vectors

TOXIC EFFECT OF A CERTAIN MEDICINAL PLANT EXTRACTS AGAINST LARVAE OF MOSQUITO SPECIES Culiseta longiareolata (MACQUART, 1838)

The domestic mosquito Culex pipiens and Culiseta longiareolata are considered to be the most important mosquito species in Algeria, due to their large geographical distribution and abundance. Instead of causing environmental nuisance, they transmit diseases to the animals. The mosquito control, using conventional insecticides becomes harmful to human and to the environment and in addition mosquitoes have developed a resistance against these products. These reasons have encouraged scientists to propose new eco-friendly and effective alternatives to control insects. Plants extracts have showed a promising agents for pest treatments.  In order to test a botanical larvicide against mosquito, extracts were prepared from the leaves of Marrubium vulgare, Laurus nobilis, Eucalyptus globulus, and Myrtus communis and the extractions were done with methanol, using a Soxhlet extractor. Bioassay was carried out, using different concentrations against the fourth mosquito larvae of the C. longiareolata.  The toxicity of the tested extracts was evaluated and the lethal concentrations, LC50 and LC90) values were estimated. The obtained results indicated a sensitivity of Cs. longiareolata larvae to the four plants species, with dose-response relationship mortality. The lethal concentrations were calculated with their confidence limits and their values were for LC50 of 6.13, 7.03, 9.60 and 17.84g/l, while the LC90’s were 22, 37.19, 75.69 and 92.76g/l for M. vulgare, L. nobilis, E. globulus, and Myrtus communis respectively. These toxicological assays, using these autochthon plant extracts could be developed as an alternative compound for mosquito control programme