Percentage Repellency Research Articles

Repellent, oviposition-deterrent and egg-hatching inhibitory effects of some plant essential oils against citrus mealybug, Planococcus citri Risso (Hemiptera: Pseudococcidae)

The citrus mealybug (Planococcus citri) is a serious pest of citrus groves in Turkey and has recently caused considerable damages to some cut flowers (especially, roses and orchids) in greenhouses in Antalya (southwestern Turkey). In this study, repellent and oviposition-deterrent activities of essential oils from anise (Pimpinella anisum), rosemary (Rosmarinus officinalis), peppermint (Mentha piperita), Turkish oregano (Origanum onites) and thyme (Thymus vulgaris) were investigated against female adults of P. citri under laboratory conditions. The results from the study showed that all the essential oils tested had a repellent activity in varying degrees, and the repellency was concentration and time dependent. Based on the highest dose (5 mL/L water) and the longest time period after the insect introduction (96 h), the oils from O. onites and T. vulgaris had the highest percent repellency in both choice and no-choice tests (O. onites: 88.9 and 65.4%; T. vulgaris: 88.8 and 69.6%, respectively), and followed by P. anisum (80.1 and 50%) and R. officinalis (57.1 and 45.2%) oils. In the oviposition deterrency assays using the highest concentration (5 mL/L water), O. onites essential oil showed the most potent oviposition deterrency (63.7%) resulting in the lowest mean number of eggs laid by the mealybug females (48.8 eggs per female) followed by P. anisum (56.9%). Furthermore, these two oils had the most potent egg-hatching inhibitory effects and inhibited egg hatching by 59.2 and 46.8%, respectively. Overall results suggest that the essential oils tested may help for us in controlling P. citri populations in various agroecosystems.

Insectifugal and insecticidal potentials of two tropical botanical essential oils against cowpea seed bruchid.

Essential oils (EO) obtained from Xylopia parviflora root bark and Hoslundia opposita leaf via hydro distillation were analysed by GC-MS and evaluated for their insectifugal (repellent) and insecticidal activities against cowpea seed bruchid (Callosbruchus maculatus Fabricius), a cosmopolitan pest of cowpea seeds. X. parviflora was predominated by sesquiterpenes (59.57%), with the main compounds being β-himachalene (22.68%), 1,7,7,Trimethylbicyclo[2.2.1]hept-5-en-2-ol (19.68%), β-elemene (14.41%), 5(1H)-Azulenone, 2,4,6,7,8,8a-hexahydro-3,8-dimethyl-4-(1-methylethylidene)-(85-cis)- (12.38%) and (-)-α-parasinsen (8.34%). The predominant compounds in H. opposita EO were 1,8-cineole (61.15%), followed by α-terpineol (16.81%) and β-phellandrene (13.25%). Percentage repellence at application rates of 0.66-1.32μl/cm2 (46.93-73.07%) was significantly (p<0.05) higher than that of control (17.73%). RD50 (repellence dose for 50% of treated adults) for H. opposita (0.43μl/cm2) was not significantly different from the value for X. parviflora (0.60μl/cm2). Although higher percentage of male mortality than female mortality was observed due to topical application of the EOs, the disparity was not significant. The results of correlation of the chemical groups of the EOs with the insectifugal activity indicate that the observed bioactivity was due to the synergistic effects of the chemical groups. The two EOs are therefore recommended for incorporation into bruchid protection schemes in the tropics.

MICROENCAPSULATED LEMONGRASS OIL FOR MOSQUITO REPELLENT FINISHING OF KNITTED COTTON WEAR

Objective: This study was conducted to design the textile structure with mosquito repellent behavior using microencapsulated lemongrass extract.Methods: Lemongrass oil extracted from Cymbopogon citratus by a hydro distillation process, which was used as core and gum acacia was used as wall material. About 10% W/V gum acacia was allowed to swell with hot water and stirred well with a temperature of 50°C. Further to this mixture 10 ml of lemongrass extract was mixed and stirred around 400 rpm for 15 minutes. Subsequent with this process, 20% V/V sodium sulfate was added then the stirrer speed was reduced 80 rpm, and then 5 ml of 17% formaldehyde was added along with this mixture. Finally, the microcapsules were obtained. Then, this lemongrass extract capsule mixture was coated on the fabric through pad dry cure method.Results: Mosquito repellent study was carried out through the excito chamber method and assessed the mosquito repellency percentage. The maximum mosquito repellency percentage was obtained around 90%. Wash durability, abrasion resistance, air permeability, and bursting strength of the coated textiles were also studied. Scanning electron microscopy analysis and gas chromatography analysis were also performed for the samples.Conclusion: It was proved that lemongrass microencapsulated textiles provide good resistance against mosquito bites and also concluded that this process is one of eco-friendly

Repellent effects of the essential oils of Cymbopogon citratus and Tagetes minuta on the sandfly, Phlebotomus duboscqi

BackgroundThe sandfly, Phlebotomus duboscqi is a vector of zoonotic cutaneous leishmaniasis (ZCL) that is an important public health problem in Eastern Africa. Repellents have been used for protection of humans against vectors of ZCL and other vectors that transmit killer diseases including malaria, Rift Valley fever, dengue, and yellow fever. The repellent effects of different doses of the essential oils from the lemon grass, Cymbopogon citratus and Mexican marigold, Tagetes minuta were evaluated in a two-chamber bioassay against 3- to 7-day-old unfed females of P. duboscqi in the laboratory. The results were compared with those that were obtained when test animals were treated with an equivalent dose of diethyl-3-methylbenzamide, which is a repellent that is commonly used as a positive control.ResultsOverall, percentage repellency increased with increasing doses of the essential oils while biting rates decreased with increasing concentrations of the oils. Further, the oil of C. citratus was more potent than that of T. minuta with regard to protection time and biting deterrence. The effective doses at 50% (ED50) and at 90% (ED90) for the oil of C. citratus, were 0.04 and 0.79 mg/ml, respectively. Those of the oil of T. minuta were 0.10 and 12.58 mg/ml. In addition, the percentage repellency of 1 mg/ml of the essential oils of C. citratus and T. minuta against sandflies was 100% and 88.89%, respectively. A lower dose of 0.5 mg/ml of the oils, elicited 89.13% repellency for C. citratus and 52.22% for T. minuta.ConclusionThe laboratory tests showed that the essential oils of the two plants were highly repellent to adult sand flies, P. duboscqi. Thus, the two essential oils are candidate natural repellents that can be used against P. duboscqi due to their high efficacy at very low doses, hence, the envisaged safety in their use over chemical repellents. It remains to carry out clinical studies on human subjects with appropriate formulations of the oils prior to recommending their adoption for use against the sandflies.

The Larvicidal and Repellent Effect of Bush Mint Plant (&lt;i&gt;Hyptis suaveolens&lt;/i&gt;) and Hairy Sicklepod (&lt;i&gt;Senna hirsuta&lt;/i&gt;) Extracts against the Larvae and Adult of &lt;i&gt;Culex quinquefasciatus&lt;/i&gt;

The efficacy of hexane leaf extracts of Hyptissuaveolens and Senna hirsuta as a larvicide and repellent against the 4 th instar larvae and adult of Culexquinquefasciatus was investigated. Extraction was done using Soxhlet apparatus. Twenty fourth instar larvae of Culexquinquefasciatus were exposed to various concentrations (5%, 10%, 15%, 20%, 30% and control) and observed over 3 hours for mortality. Repellency against the adult mosquito was investigated on five human volunteers who did not use any lotion, soap or perfume on the arm. The experiment was carried out during the day in a dark shade. Percentage repellence was recorded every 10minutes for a period of 1 hour. Lethal concentration 50% (LC 50 ) which is the concentration required to kill half the members of the tested population after 3 hours of exposure was used to assess the larval mortality. Result indicated the combined extract with LC 50 6% gave a higher mortality than the individual extract of Hyptis suaveolens (LC 50 6.4%) and Senna hirsuta (LC 50 7.5%). Similarly, repellence was highest in the combined extract with 75% repellency than in the extracts of Hyptis suaveolens (70%) and Senna hirsuta (50%). The result observed in the study was analyzed using Analysis of Variance. There was a significant difference from the use of individual extracts (P< 0.05). From the result of the study, it was deduced that the efficacy of the treatments increased with an increasing exposure time and concentration. The findings of the study revealed the efficacy of hexane leaf extracts of Hyptis suaveolens and Senna hirsuta as good larvicide and repellent against Culex quinquefasciatus especially in the synergistic state.

Biological Activity of Essential Oil from Piper nigrum Against Nymphs and Adults of Blattella germanica (Blattodea: Blattellidae)

Cockroaches are a common and important pest that inhabits various public places such as warehouses, restaurants, etc. Essential oil from Piper nigrum was evaluated for its repellent activity against nymphs (1st, 2nd, 3rd, 4th instars) and adult German cockroaches, Blattella germanica (L.), under laboratory practical conditions. Laboratory trials were conducted using preference tests with the absence of food and the presence of food, and choice tests (control and treatment) in restaurants. The essential oil repelled both nymph and adult stages. The maximum repellencies recorded were 73.33±4.28% and 63.33±3.65% at 1 h for adults before and after food and 53.33±2.89% and 45.00±3.70% at 1 h for nymphs before and after food, respectively, in the laboratory. Whereas repellency percentages from P. nigrum were 65.19±6.90% and 55.00±8.56% at 6 h and 12 h, respectively, in kitchen experiments. Results from this study indicated that essential oil from P. nigrum could be effective to manage nymph and adult stages of German cockroaches.

Bioactivities and Chemical Constituents of Essential Oil Extracted from Artemisia anethoides Against Two Stored Product Insects.

The chemical constituents of the essential oil extracted from Artemisia anethoides and the bioactivities of essential oil against Tribolium castaneum and Lasioderma serricorne were investigated. The main components of the essential oil were 1,8-cineole (36.54%), 2-isopropyl-5-methyl-3-cyclohexen-1-one (10.40%), terpinen-4-ol (8.58%), 2-isopropyltoluene (6.20) and pinocarveol (5.08%). The essential oil of A. anethoides possessed contact and fumigant toxicities against T. castaneum adults (LD50 = 28.80 μg/adult and LC50 = 13.05 mg/L air, respectively) and against L. serricorne (LD50 = 24.03 μg/adult and LD50 = 8.04 mg/L air, respectively). The crude oil showed repellent activity against T. castaneum and L. serricorne. Especially, the percentage repellency of essential oil was same level with DEET (positive control) against T. castaneum. The results indicated that the essential oil of A. anethoides had the potential to be developed as insecticide and repellent for control of T. castaneum and L. serricorne.

Chemical Composition and Bioactivity of Lippia adoensis Hochst ex. Walp (Verneneaceae) Leaf Essential Oil Against Callosobruchus maculatus Fabricius (Coleoptera: Chrysomelidae)

Essential oil (EO) of Nigeria-grown Lippia adoensis leaf was analyzed using gas chromatography mass spectrometry (GCMS) and its fumigant and repellent properties against Callosobruchus maculatus were evaluated. Sixteen compounds predominated by monoterpenes were identified. The major compounds were Eucalyptol (28.36%), α-Terpineol (25.99%), γ-Terpinene (15.24%), α-Pinene (5.08%), 1H-Cyclopropa[a]naphthalene (4.25%) and 1, 3, 6, 10-Dodecatetraene (3.74%). Percentage mortality due to fumigant toxicity was dose- and exposure period-dependent. One hour after treatment (HAT), application of L. adoensis leaf EO at 107 μL · L−1 air caused significantly (p<0.05) higher mortality (50.00%) than 0.00% mortality observed at 0–53 μL · L−1 air, but not significantly (p<0.05) different from 22.50% observed in 80 μL · L−1 air. At 3 HAT, application of L. adoensis EO at 80 μL · L−1 air caused significantly higher mortality (90.00 %) than mortality observed at 0 μL · L−1 air. At 6 HAT, application of L. adoensis EO at 53–107 μL · L−1 air caused significantly higher mortality (100.00 %) than that was observed in the control. The same trend was observed at 12 HAT where 100 % mortality observed in 27–107 μL · L−1 air was significantly greater than 13.33 % observed in the control. At 3 HAT, percentage repellence was significantly (p<0.05) affected by doses. Application of EO at 10–30 μL · cm−2 caused class V repellence (86.67%–100%) compared with the control which caused class I repellence (0–20%).

ALOE VERA (L.) BURM. F. : A HIGHLY USEFUL INDIAN TRADITIONAL PLANT FOR THE MANAGEMENT OF MAIZE STORAGE PEST, SITOPHILUS ORYZAE L. (COLEOPTERA: CURCULIONIDAE)

Aloe vera (L.) Burm. f. is an important Indian traditional plant possessing wide range of biological activities. The present study is aimed to determine the repellent and contact toxicity of methanolic extracts of gel, root and leaf peel parts of fifteen A. vera accessions collected from 15 locations in India against maize storage pest, Sitophilus oryzae(L.). Petri dish choice bioassay and filter paper impregnation methods were used to determine repellent and contact toxicity respectively. Analysis of the results reveals that aloin A, the major metabolite of A. vera, at 0.02% w/v concentration possessed strong repellent activity (85.2 %) than sample AV 11a (gel of A. vera) at 5% w/v (82.7%) after 24-h of exposure. Interestingly, the percent repellency increases up to 5-h in all extracts screened. Aloin A at 0.0024 mg/cm2 showed 58.0% mortality against S. oryzae followed by sample AV 13b (leaf peel) at 0.6 mg/cm2 (56.0%) after 14 days of treatment. The content of Aloin A present in the six A. vera extracts, exhibiting highest toxicity and repellency, was determined by Ultra Performance Liquid Chromatography. The percent repellency and toxicity of A. vera vary with geographical location, plant parts, major metabolite concentration and exposure time. The potentiality of these plant extracts could be useful towards the development of effective bio repellent to S. oryzae in stored maize.

The formulation of the essential oil of Piper aduncum Linnaeus (Piperales: Piperaceae) increases its efficacy as an insect repellent.

The essential oil (EO) of Piper aduncum Linnaeus, known as 'sireh lada' to locals Malaysian, has the potential to be used as an alternative to synthetic insect repellents such as N,N-diethyl-meta-toluamide. However, the EO's efficacy as a repellent decreases after application due to the high volatility of its active ingredients. A number of studies have showed that optimizing the formulation of plant-based EOs can improve their efficacy as repellents. The present study sought to evaluate the effectiveness of 10% P. aduncum EO in ethanol and in three different semisolid formulations: ointment, cream and gel. These formulations were tested on Aedes aegypti under laboratory conditions. Each formulation was applied to the subject's hands, which were then inserted into a cage containing 25 nulliparous A. aegypti. The number of mosquitoes landing on or biting each subject's hand was recorded, and the repellency percentage, landing/biting percentage and protection time for each of the formulations were compared. There were no statistically significant differences between the semisolid EO formulations with regards to the repellency percentage and the landing/biting percentage at 4 h post-application. All three semisolid EO formulations were able to repel >65% of the A. aegypti at 4 h post-application. The EO ointment formulation provided a protection time (182.5 ± 16.01 min) that was statistically significantly longer than that associated with the EO gel formulation (97.5 ± 14.93 min). Meanwhile, the EO cream formulation provided a protection time of 162.5 ± 6.29 min. As the EO cream and ointment formulations displayed better repellent properties than the EO gel formulation, they appear to be the most promising P. aduncum EO formulations to be developed and commercialized as alternatives to synthetic repellents.

DAYA TOLAK INFUSA DAUN PANDAN WANGI (Pandanus amaryllifolius Roxb.) TERHADAP PELETAKAN TELUR NYAMUK Aedes spp

Aedes spp larval resistance against chemical insecticide has been reported in many country. The new methods that can be used to control the mosquito populations as a dengue fever vector and alternative compound which is safe for environtment and can’t cause the resistance need to be found. Pandan leaves have aromatic fragrant that can be expected as a oviposition deterrent effect against Aeses spp mosquito. To know oviposition deterrent effects and optimum consentration of pandan leaves (Pandanus amaryllifolius Roxb.) infusa against Aedes spp. This research was an experimental research using six groups of concentration. There was 0 mL/L (control), 3 mL/L, 3,5 mL/L, 4 mL/L, 4,5 mL/L and 5 mL/L. Every groups would be repeated by fourth. Ovitraps with different concentration of pandan leaves infusa placed at research location. The mosquito eggs that caught at the ovitrap would be counting and identifying in the laboratorium. Data was analyzed using One Way Anova test via computer program SPSS 19.0 and then continued by LSD test with 95% confidence level. The repellency percentage at 3 mL/L concentration is 30.35%; 3,5 mL/L is 55.35%; 4 mL/L is 65.17%; 4,5 mL/L is 82.14% and 5 mL/L is 100% with significancy value is 0,000 (p<0,05).

Aktivitas Repelensi dan Insektisidal Beberapa Ekstrak dan Minyak Nabati terhadap Hama Gudang Ephestia cautella

&lt;p&gt;Ephestia cautella&lt;em&gt; is one &lt;/em&gt;&lt;em&gt;type &lt;/em&gt;&lt;em&gt;of storage pest&lt;/em&gt;&lt;em&gt;s&lt;/em&gt;&lt;em&gt; that causes a decrease in cocoa bean&lt;/em&gt;&lt;em&gt; &lt;/em&gt;&lt;em&gt;quality. Control of th&lt;/em&gt;&lt;em&gt;is&lt;/em&gt;&lt;em&gt; pest using chemical insecticides is not recommended because it is harmful to the environment and consumer health. The research aimed to &lt;/em&gt;&lt;em&gt;examine&lt;/em&gt;&lt;em&gt; the repellency and insecticidal activity of several types of extract and botanical oil &lt;/em&gt;&lt;em&gt;against&lt;/em&gt;&lt;em&gt; &lt;/em&gt;E. cautella&lt;em&gt; larvae. The &lt;/em&gt;&lt;em&gt;research was&lt;/em&gt;&lt;em&gt; conducted &lt;/em&gt;&lt;em&gt;in&lt;/em&gt;&lt;em&gt; the Plant Protection Laboratory, Indonesian Industrial and Beverage Crops Research Institute, &lt;/em&gt;&lt;em&gt;from &lt;/em&gt;&lt;em&gt;March to November 2012. &lt;/em&gt;&lt;em&gt;Botanical&lt;/em&gt;&lt;em&gt; materials used &lt;/em&gt;&lt;em&gt;were&lt;/em&gt;&lt;em&gt; water extracts from &lt;/em&gt;Ageratum conyzoides&lt;em&gt; leaves, &lt;/em&gt;Azadirachta indica&lt;em&gt; seeds, &lt;/em&gt;&lt;em&gt;and &lt;/em&gt;Allium sativum&lt;em&gt; tubers, as well as oil from &lt;/em&gt;Reutalis trisperma&lt;em&gt;, &lt;/em&gt;Syzygium aromaticum&lt;em&gt;, and &lt;/em&gt;Andropogon nardus&lt;em&gt;, &lt;/em&gt;&lt;em&gt;with respective&lt;/em&gt;&lt;em&gt; concentration of 0.5%. The insects test used was the 3rd instar larvae &lt;/em&gt;&lt;em&gt;generated&lt;/em&gt;&lt;em&gt; in the laboratory. &lt;/em&gt;&lt;em&gt;P&lt;/em&gt;&lt;em&gt;reliminary testing &lt;/em&gt;&lt;em&gt;of the &lt;/em&gt;&lt;em&gt;repellency activity was performed &lt;/em&gt;&lt;em&gt;used the&lt;/em&gt;&lt;em&gt; multiple&lt;/em&gt;&lt;em&gt;-&lt;/em&gt;&lt;em&gt;choice method, while subsequent testing used the dual&lt;/em&gt;&lt;em&gt;-&lt;/em&gt;&lt;em&gt;choice method with the parameter&lt;/em&gt;&lt;em&gt;s&lt;/em&gt;&lt;em&gt; of larvae &lt;/em&gt;&lt;em&gt;number remains i&lt;/em&gt;&lt;em&gt;n each treatment until 72 hours. The insecticidal activity was conducted using residual &lt;/em&gt;&lt;em&gt;method &lt;/em&gt;&lt;em&gt;on the feed substitute, by calculating mortality rate of the test insects. Observations were made at 24, 48, and 72 hours after treatment. The results showed that water extract &lt;/em&gt;&lt;em&gt;from&lt;/em&gt;&lt;em&gt; &lt;/em&gt;A. sativum&lt;em&gt; bulbs and &lt;/em&gt;A. conyzoides&lt;em&gt; leaves have high repellency percentage on the &lt;/em&gt;E. cautella&lt;em&gt; larvae, i.e. &lt;/em&gt;&lt;em&gt;of &lt;/em&gt;&lt;em&gt;81.33% and 78.67%, respectively. Thus, the&lt;/em&gt;&lt;em&gt;se&lt;/em&gt;&lt;em&gt; two vegetable extracts have the potential to be &lt;/em&gt;&lt;em&gt;used as cocoa bean protectant &lt;/em&gt;&lt;em&gt;from &lt;/em&gt;&lt;em&gt;storage pest &lt;/em&gt;&lt;em&gt;attack&lt;/em&gt;&lt;em&gt;s.&lt;/em&gt;&lt;em&gt; The extract&lt;/em&gt;&lt;em&gt;s&lt;/em&gt;&lt;em&gt; &lt;/em&gt;&lt;em&gt;from&lt;/em&gt;&lt;em&gt; &lt;/em&gt;A. indica&lt;em&gt; seed, &lt;/em&gt;A. sativum&lt;em&gt; bulbs, as well as&lt;/em&gt;&lt;em&gt; oil from&lt;/em&gt;&lt;em&gt; &lt;/em&gt;R. trisperma&lt;em&gt; and &lt;/em&gt;S. aromaticum&lt;em&gt; showed insecticidal properties that are able to kill &lt;/em&gt;E. cautella&lt;em&gt; larvae.&lt;/em&gt;&lt;em&gt;&lt;/em&gt;&lt;/p&gt;

Anti-dengue efficacy of bioactive andrographolide from Andrographis paniculata (Lamiales: Acanthaceae) against the primary dengue vector Aedes aegypti (Diptera: Culicidae)

The current study investigated the toxic effect of the leaf extract compound andrographolide from Andrographis paniculata (Burm.f) against the dengue vector Ae. aegypti. GC–MS analysis revealed that andrographolide was recognized as the major chemical constituent with the prominent peak area compared with other compounds. All isolated toxic compounds were purified and confirmed through RP-HPLC against chemical standards. The larvicidal assays established at 25ppm of bioactive compound against the treated instars of Ae. Aegypti showed prominent mortality compared to other treated concentrations. The percent mortality of larvae was directly proportional to concentration. The lethal concentration (LC50) was observed at 12ppm treatment concentration. The bioactive andrographolide considerably reduced the detoxifying enzyme regulations of α- and β- carboxylesterases. In contrast, the levels of GST and CYP450 significantly increase in a dose dependent manner. The andrographolide also showed strong oviposition deterrence effects at the sub-lethal dose of 12ppm. Similarly, the mean number of eggs were also significantly reduced in a dose dependent manner. At the concentration of 12ppm the effective percentage of repellency was greater than 90% with a protection time of 15–210min, compared with control. The histopathology study displayed that larvae treated with bioactive andrographolide had cytopathic effects in the midgut epithelium compared with the control. The present study established that bioactive andrographolide served as a potential useful for dengue vector management.

English

Acanthoscelides obtectus Say, a principal pest of kidney beans Phaseolus vulgaris L. in the Mediterranean area, is a multivoltine and oligophagous bruchid that damages not only host plant (kidney bean) but also other Leguminosae species. Essential oils of Rutaceae: Citrus reticulata L. and Citrus limonum L. and of Lamiaceae Mentha piperita L. and Lavandula angustifolia L. were evaluated by fumigation upon A. obtectus adults using concentrations of 13.33, 40, 80 and 106.66 µl/L air. Their vapours have a toxic increasing effect depending upon concentrations and time exposure. Lamiaceae essential oils exhibited the higher fumigant activity inducing mortality of about 37.5 to 100% and 45.25 to 95% for, respectively lavender and peppermint essential oils after 24 h only. Mortality percentages of 85 and 72.5%, respectively for C. limonum and C. reticulata were recorded after exposure time of 96 h at the highest dose. Repellency activity studied at 0.105, 0.315, 0.631 and 0.842 µl/cm2 concentrations showed a higher repellency percentage of 71.25% for peppermint essential oil on A. obtectus adults. Our results suggest that Lamiaceae essential oils more than Rutaceae ones may be useful as a seed protecting tool with fumigation effects against A. obtectus and could replace synthetic insecticides which are harmful to the environment. Key words: Acanthoscelides obtectus, Phaseolus vulgaris, essential oils, repellency, fumigant toxicity.

Increasing Efficacy of Eucalyptus Oil as Repellent Against Rattus rattus by Controlled Release Through Encapsulated Wax Blocks

Plant based non-lethal repellents are most suitable for rodent control. Present studies were conducted to increase the efficacy of eucalyptus oil as repellent against black rat, Rattus rattus by its controlled release through encapsulated wax blocks. Mature and healthy R. rattus of both sexes were exposed to 5, 10 and 20 % eucalyptus oil encapsulated in wax blocks in laboratory pens in bi-choice tests. Each concentration was applied through three different modes of application i.e. daily, once a week, and every second day per week. Repellent effect of the oil was assessed based on food consumption from treated and untreated sides of a chamber for four days a week. Food consumption was found to be significantly (P ≤ 0.05) low from treatment side as compared to that observed on untreated side at all the three concentrations tested indicating repellent effect of the eucalyptus oil against R. rattus. Percent repellency with eucalyptus oil encapsulated in wax blocks at all the three concentrations was found to be similar. Being the minimum effective concentration, present studies suggest the use of 5 % eucalyptus oil encapsulated in wax blocks as repellent against R. rattus. This method may be used as part of integrated pest management technology for managing rats in enclosed store houses.

Chemical and biological profiles of essential oils from Mentha spicata L. leaf from Bejaia in Algeria

Air-dried leaves of Mentha spicata L. were collected in Bejaia location (Algeria) during 2013. The plant samples were distillated by Clevenger apparatus and the essential oils obtained were analyzed by GC and GC/MS. Fifty compounds amounting to 98.9% of the oil, were identified. The major components of the oil were carvone (48.5%), limonene (20.7%), and 1,8-cineole (5.4%). This oil exhibited high antimicrobial activity with a high effectiveness against Candida albicans strain with a diameter of growth inhibition zones of ranging from 14.3 ± 1.5 to 44.3 ± 1.1 mm. The antioxidant activity determined by five different test systems showed that the oil exhibits moderate activity. The insecticidal activity has been tested on the adults of Rhyzopertha dominica F., the main pest of wheat. Contact and fumigant toxicity assays showed mortality percentages of 14.0 and 34.5% respectively at the dose of 2 μL/mL and the repellency percentage was 56.2% at 30 minutes.

Efficacy of Mosquito Repellent and Adulticidal Activities of Halophila Ovalis Extract Against Filaria Vectors

The repellent and adulticidal activities were analyzed for ethanol extract of Halophila ovalis against Culex quinquefasciatus (Cx. quinquefasciatus). The extraction was done in soxhlet apparatus using ethanol as solvent. The repellent activity of the Halophila ovalis was determined against Culex quinquefasciatus in different concentration of the extract at 100, 150, 200, 250 and 300 μL/cm2. Adulticidal activity of the Halophila ovalis extract was tested against four to five day old female adults of Culex quinquefasciatus. The adult mortality was observed 24h under the laboratory conditions. Each experiment was conducted with the three replicates and a concurrent control group. As per the WHO guidelines, the experiments were conducted. At 250 μL of concentration extracts of Halophila ovalis showed maximum repellency percentage of 95% against Culex quinquefasciatus. The highest adulticidal activity was observed in 100 μL concentration against Culex quinquefasciatus with LC50 were (50.2 ± 0.7) μL/ml and (51.2 ± 0.9) μL/ml. The GC-MS reveals unique chemical compounds obtained from the extract of Halophila ovalis. The present study identifies the active insecticidal compounds from Halophila ovalis by GC-MS and from the results it can be concluded the extract of Halophila ovalis can be novel efficient biocontrol source against filariasis mosquitoes.

Chemical composition of Cupressus lusitanica and Eucalyptus saligna leaf essential oils and bioactivity against major insect pests of stored food grains

The leaf essential oils from Cupressus lusitanica, Miller and Eucalyptus saligna, Smith obtained by hydrodistillation were analyzed by GC/MS and also screened for their insecticidal and repellent effects against adult Tribolium castaneum, Acanthoscelides obtectus, Sitotroga cerealella and Sitophilus zeamais. The C. lusitanica oil contained mainly umbellulone (18.38%) and α-pinene (9.97%) whereas the E. saligna oil was dominated by α-pinene (24.40%) and 1,8-cineole (24.26%). Bioassays showed that of the four insect species tested, A. obtectus and S. cerealella were the most susceptible to the oils, with LC50 values of 0.05–0.11% v/w in contact toxicity and 4.07–7.02μl/L air in space fumigation. Except in T. castaneum with percentage repellence (PR) values of 65–92.5%, the other test insects recorded PR values less than 30%. The PR values decreased with exposure time in all insects except in T. castaneum. Our results show that C. lusitanica and E. saligna essential oils are promising insecticides and repellents to be used against insect pests of stored food grains.

Evaluación de extractos totales como repelente para el control de Tribolium castaneum Herbst, 1979 (Coleoptera: Tenebrionidae)

Objective: To evaluate the repellent activity of six total extracts derived from plants of the departmento de Choco. The repellent activity of the total extracts was tested against adult insects of Tribolium castaneum Herbst, 1979, pests of stored grains. Methodology: During in vivo tests, the repellent activity was measured using the area preference technique by quantifying the obtained percentage of repellency at different exposure concentrations. The results were analyzed by paired t-test to determine signi cant differences (p<0.05). Moreover, the comparison between the repellency percentages (RP) the different extracts was performed using analysis of variance (ANOVA) by means of Dunn’s post test to assess comparisons with the positive control. Results: The evaluated extracts showed a proportional increase of its repellent activity to the concentration increase showing an independent effect. As a result, the more effective extracts were the derived from Ocimum campechianum variedad blanca, Piper divaricatum and Palicuria guianensis with repellency percentages of 92%, 75% and 74% respectively. Conclusions: These results presents suggest a potential use of the six plants extract tested to control T. castaneum from which, O. campechianum var white extract is the most recommended as it showed high repellent activity. Additionally, this study constitu- tes a big contribution to bio-prospecting of Choco Flora and to the sustainable development of the region.

Applicability of citronella oil (Cymbopogon winteratus) for the prevention of mosquito-borne diseases in the rural area of Tikapur, far-western Nepal

Mosquito-borne diseases are a serious global problem, particularly in tropical and sub-tropical countries such as Nepal. Citronella oil is a natural mosquito repellent as well as a local fragrance in Nepal, which is accessible at very low cost because citronella plants are widely cultivated in rural areas of the Terai belt in Nepal. This study was conducted using a real-life randomized controlled pilot trial to confirm the effectiveness and applicability of locally-produced citronella oil as a mosquito repellent for the prevention of mosquito-borne diseases in Nepal. A repellency activity test was performed with 100% citronella oil (Cymbopogon winteratus) from April to May 2013 in the Tikapur Municipality of the Kailali district, Nepal. The test was divided into two trials: an indoor exposure (IE) test (N=101) and an outdoor exposure (OE) test (N=140) from 5.00 pm to 7.00 pm. Each trial contained an experimental citronella oil-applied group and a non-applied (control) group. The outcome measures were the protective effect of citronella oil against mosquitoes, the number of mosquito bites, the repellency percentage, the smell satisfaction and the irritation level. Experimental group had a significant protective effect against mosquito bites in IE (96.5%, n=57) and OE (95.7%, n=70) tests compared to the control group in IE (29.5%, n=44) and OE (28.6%, n=70) tests (experimental vs control groups, p<0.001). The repellency percentage for the OE test was 96.7%. In the smell satisfaction test (n=127), most of the participants responded with high satisfaction: 'good' (67.7%), 'very good' (16.5%), 'bad' (13.4%) and 'very bad' (2.4%). IE and OE tests showed similar satisfaction levels in each category. In the irritation level test (n=127), 87.4% and 12.6% responded with no irritation and slight irritation, respectively. There were no reports of moderate or severe irritation. The topical application of citronella oil can be employed as an easily-available, affordable and effective alternative mosquito repellent to prevent mosquito-borne diseases in rural areas such as Tikapur, Nepal.