Combinations of Lemongrass and Star Anise Essential Oils and Their Main Constituent: Synergistic Housefly Repellency and Safety against Non-Target Organisms.

The present study evaluated the housefly repellency of single-component formulations and combinations of lemongrass and star anise essential oils (EOs) and their main constituents. The efficacies of the combinations were compared against those of single-component formulations and DEET. Safety bioassays of all formulations and DEET on non-target species-guppy, molly, dwarf honeybee, and stingless bee-were conducted. GC-MS analysis showed that the main constituent of lemongrass EO was geranial (46.83%) and that of star anise EO was trans-anethole (92.88%). All combinations were highly synergistic compared to single-component formulations, with an increased repellent value (IR) of 34.6 to 51.2%. The greatest synergistic effect was achieved by 1.0% lemongrass EO + 1.0% trans-anethole combination, with an IR of 51.2%. The strongest, 100% repellent rate at 6 h was achieved by 1.0% geranial + 1.0% trans-anethole. They were twice as effective as DEET and caused obvious damage to housefly antennae under microscopic observation. All single-component formulations and combinations were benign to the four tested non-target species. In contrast, DEET was highly toxic to them. The synergistic repellency and biosafety of these two combinations are compellingly strong support for developing them into an effective green repellent.

Adulticidal synergy of two plant essential oils and their major constituents against the housefly Musca domestica and bioassay on non-target species.

Single and mixture formulations of lemongrass (Cymbopogon citratus (DC.) Stapf.) and star anise (Illicium verum (J. Presl.)) essential oils (EOs) and their major constituents were assayed for their adulticidal activities against housefly, Musca domestica L., and two non-target species, stingless bee (Tetragonula pegdeni Schwarz) and guppy (Poecilia reticulata Peters). The efficacies of the mixture formulations were compared against those of the single formulations and 1.0% α-cypermethrin, a common synthetic insecticide. GC-MS analysis found that the major constituent of lemongrass EO was geranial (45.23%), and that of star anise EO was trans-anethole (93.23%). Almost all mixture formulations were more effective in adulticidal activity against housefly adults than single formulations and 1.0% α-cypermethrin. A mixture of 1.0% lemongrass EO + 1.0% trans-anethole exhibited the strongest synergistic insecticidal activity with a 100% mortality rate (KT50 of 3.2 min and LT50 of 0.07 h). The relative percentage increase in mortality rate over single formulations was between 1.6 and 91.9%. In addition, it was three times more effective than 1.0% α-cypermethrin. To find the mechanism of adulticidal action, scanning electron microscopy (SEM) was done to find morphological aberrations, such as antennal and mouthpart aberrations, after the houseflies were treated with 1.0% lemongrass EO + 1.0% trans-anethole. The aberrations included deformed and abnormal shape of arista and flagellum, change in labellum pigmentation, and damage to pseudotracheae. Regarding toxicity against non-target species, all single and mixture formulations were not toxic to the two non-target species, while 1.0% α-cypermethrin was highly toxic. To conclude, a mixture of 1.0% lemongrass EO + 1.0% trans-anethole can be an excellent, natural, sustainable housefly adulticidal agent.

Ovicidal toxicity of plant essential oils and their major constituents against two mosquito vectors and their non-target aquatic predators.

Plant essential oil (EO) is a natural alternative to synthetic chemical insecticides for mosquito control. EOs from Citrus aurantium L., Cymbopogon citratus (Stapf.), and Cinnamomum verum (J. Presl.) were selected for topical assay of their ovicidal activity against Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse). Their efficacy was compared to that of 1% (w/w) temephos. In addition, their non-toxicity against aquatic mosquito predators, Poecilia latipinna and Poecilia reticulata, was tested. Found by GC-MS analysis, the major constituent of C. verum EO was trans-cinnamaldehyde, of C. aurantium EO was D-limonene, and of C. citratus EO was geranial. Both C. verum EO and trans-cinnamaldehyde at a high concentration (30,000 ppm) exhibited high ovicidal activity against Ae. aegypti and Ae. albopictus eggs after 48 h of incubation with an inhibition rate of 91.0-93.0% for C. verum EO and 96.7-95.2% for trans-cinnamaldehyde. The combination of C. verum EO + geranial exhibited the strongest synergistic inhibition activity (100%) against the two mosquito vectors and was five times more effective than temephos. Moreover, they were not toxic to the non-target fishes. As a safe ovicidal agent for mosquito egg control, the combination of C. verum EO + geranial has excellent potential.

Ovicidal and repellent activities of several plant essential oils against Periplaneta americana L. and enhanced activities from their combined formulation.

Natural ovicidal and repellent agents against Periplaneta americana L. are urgently needed, and plant essential oils (EOs) can assume this role quite readily. In this study, ovicidal and repellent activities against Periplaneta americana of EOs from Cymbopogon citratus (Stapf.), Cinnamomum verum (J. Presl.), Eucalyptus globulus (Labill.), Illicium verum (Hook.f.), and Zanthoxylum limonella (Alston) in soybean oil and in ethyl alcohol were determined by topical and dual-choice assays, as well as 10% cypermethrin and a combined formulation of 5% C. verum EO + 5% I. verum EO. Cypermethrin at 10% provided the highest toxicity (100% inhibition rate) against the eggs, but only slightly higher than that (99.3%) provided by the combined EO formulation, while the highest repellent activity against the adults was provided by the combined formulation (89.5% repelled cockroaches at 48 h after treatment). In addition, all EO formulations in soybean oil provided higher ovicidal and repellent activities than those in ethyl alcohol. To conclude, the combined EO formulation in soybean oil can replace cypermethrin because their efficacy was nearly equivalent, but the combination should be much safer to use.

Combinations of plant essential oils and their major compositions inducing mortality and morphological abnormality of Aedes aegypti and Aedes albopictus.

Extensive uses of synthetic insecticides to control mosquito's populations have induced the insects to develop resistance against them, rendering them ineffective today. Moreover, they cause serious impacts on human health and the ecosystem. Therefore, safe and effective natural alternatives are needed. This study evaluated the larvicidal and pupicidal activities of essential oils (EOs) from Illicium verum and Zanthoxylum limonella and the major constituents against Aedes aegypti and Aedes albopictus mosquitoes as well as recorded their morphological aberrations at death. The GC-MS analysis showed that trans-anethole was the major constituent of I. verum EO, and limonene was the major constituent of Z. limonella EO. Both were more effective against the larvae and pupae of Ae. aegypti than those of Ae. albopictus. A 2.5% I. verum EO + 2.5% trans-anethole combination showed the highest larvicidal and pupicidal effects against Ae. aegypti and Ae. albopictus with an LT50 ranging from 0.2-6.9 h. Between the two tested constituents, trans-anethole exhibited stronger larvicidal and pupicidal activities (LC50 ranging 2.4-3.4%) against the two tested mosquito species than d-limonene (LC50 ranging 2.5-3.7%). Most importantly, 5% trans-anethole, 5% d-limonene, and 2.5% I. verum EO + 2.5% trans-anethole were more effective (LT50 ranging 0.1-0.3 h) than 1% (w/w) temephos (LT50 ranging 2.9-3.1 h). Morphological aberrations at death observed were such as color pigment and thorax shape abnormalities. To conclude, trans-anethole, d-limonene, and a combination of I. verum EO + trans-anethole, are natural compounds that not only are as effective as temephos at the time of this study, but should be also be much safer to human health.

Improved adulticidal activity against Aedes aegypti (L.) and Aedes albopictus (Skuse) from synergy between Cinnamomum spp. essential oils.

Improved natural adulticidal agents against mosquito vectors are in urgent need, and essential oils from Cinnamomum plants can assume this role quite readily. Cinnamomum verum, C. cassia, and C. loureiroi essential oils (EOs) were extracted from the barks and evaluated for their chemical composition by GC-MS. The major constituent of the three EOs was cinnamaldehyde. WHO susceptibility tests on individual and combined EOs as well as cinnamaldehyde were conducted against female adults of Aedes aegypti and Aedes albopictus. All EO combinations exhibited a synergistic effect, manifesting a higher toxicity, with a synergistic value ranging from 2.9 to 6.7. Their increasing mortality value was improved between 16.0 to 41.7%. The highest synergistic effect was achieved by an EO combination of 0.5% C. cassia + 0.5% C. loureiroi, while the highest insecticidal activity was achieved by 2.5% C. verum + 2.5% C. cassia and 1% cinnamaldehyde, with a knockdown and mortality rate of 100% and a KT50 between 0.7 and 2.1 min. This combination was more toxic to both mosquito species than 1% w/v cypermethrin. These findings demonstrate that cinnamaldehyde and synergistic combinations of C. verum + C. cassia EOs and C. cassia + C. loureiroi EOs have a high insecticidal efficacy against Aedes populations.

Adulticidal activities of Cymbopogon citratus (Stapf.) and Eucalyptus globulus (Labill.) essential oils and of their synergistic combinations against Aedes aegypti (L.), Aedes albopictus (Skuse), and Musca domestica (L.).

The knockdown and adulticidal activities of individual Cymbopogon citratus and Eucalyptus globulus essential oils (EOs) and their combinations were evaluated against three medical insect pests (Aedes aegypti, Aedes albopictus, and Musca domestica) using a WHO susceptibility test. The knockdown and adulticidal activities against the three medical insect pests of combinations of C. citratus and E. globulus EOs were higher than those of individual EOs alone. Combinations of 7.5% C. citratus + 7.5% E. globulus EOs and 10% C. citratus + 10% E. globulus EOs exhibited the highest efficacy against females of the three species with 100% knockdown and mortality rates at 1 and 24 h after exposure, respectively. Their adulticidal activities were equivalent to that of 10% w/v cypermethrin. In contrast, 70% v/v ethyl alcohol negative control was not effective at all. The combinations of EOs showed a synergistic effect, i.e., their adulticidal activity was improved by 0.2 to 100%, with increased knockdown and mortality rates, compared to individual EOs. The highest synergistic effect on effective knockdown and adulticidal activities against females of the three species was achieved by a combination of 2.5% C. citratus + 2.5% E. globulus EOs, with 36.6 to 100% knockdown rate increase and 33.5 to 98.9% mortality rate increase. This study demonstrates that all tested combinations of C. citratus and E. globulus EOs were effective adulticidal agents against females of Ae. aegypti, Ae. albopictus, and M. domestica and have a high potential for development into a botanical insecticide for controlling populations of Aedes mosquitoes and houseflies.

Toxicity of several botanical essential oils and their combinations against females of Aedes albopictus (Skuse) and Anopheles minimus (Theobald): Oviposition deterrent, ovicidal and adulticidal efficacies

Objective:To investigate the efficacies of 12 essential oil (EO) formulations from three Zingiberaceae plants (Alpinia galanga,Curcuma zedoaria,and Zingiber cas.sumunar) individually and in combination with an augmenting Eucalyptus globulus (E.globulus) EO against females of Aedes albopictus (Ae.adbopictus) and Anopheles minimus (An.minimus).Methods:These formulations were evaluated for their ovicidal,oviposition deterrent and adulticidal activities against Ae.albopictus and An.minimus by a topical method,a double-choice method and a WHO susceptibility test,respectively.Results:It was found that all formulations of Zingiberaceae plants EOs augmented with E.globulus EO were more effective in oviposition deterrent,ovicidal,and adulticidal activities against the two mosquito species than all of the formulations used without E.globulus EO.Their oviposition deterrent,ovicidal and adulticidal activities were equivalent to those of 10％ w/v cypermethrin.In contrast,70％ v/v ethyl alcohol as a control alone was not effective at all.The highest synergistic effect in effective repellency against Ae.albopictus was achieved by 5％ Alpinia galanga EO + 5％ E.globulus EO and against An.minimus was 5％ Zingiber cassumunar EO + 5％ E.globulus EO.Moreover,the highest synergistic effects in ovicidal activities against Ae.albopictus and An.minimus were achieved by 10％ Zingiber cassumunar EO + 10％ E.globulus EO and 5％ Curcuma zedoaria EO + 5％ E.globulus EO,respectively.For the adulticidal activities,the highest synergistic effect against two mosquitoes was achieved by 5％ Gurcuma zedoaria EO + 5％ E.globulus EO.Conclusions:These results suggest that Zingiberaceae plant EOs augmented with E.globulus EO have a high potential to be developed into oviposition deterrent,ovicidal,and adulticidal agents for controlling populations of Ae.albopictus and An.minimus.

Ovicidal effect of essential oils from Zingiberaceae plants and Eucalytus globulus on eggs of head lice, Pediculus humanus capitis De Geer.

BACKGROUND: Head lice infestation is an important public health problem worldwide. Chemical pediculicides have lost their efficacy because lice have developed resistance to them. Therefore, alternative pediculicides such as essential oils and herbal products have been proposed for treating head lice infestation. STUDY DESIGN: To determine the efficacy of essential oils from three Zingiberaceae plants (Curcuma xanthorrhiza, Curcuma zedoaria and Zingiber zerumbet) against head lice eggs and to investigate an augmenting substance (Eucalyptus globulus EO) for improving the efficacy of these essential oils in killing head lice eggs, especially on the inhibition of their hatching process. Permethrin pediculicide, soyabean oil, and drinking water were used as positive, negative, and neutral controls, respectively. METHODS: An immersion test was used to evaluate the ovicidal activity of 12 essential oil formulations. Head lice eggs were immersed for 1, 5 and 10 min in the treatments. Mortality rate was observed on day 7 and day 14; mortality was checked under a stereomicroscope. RESULTS: All head lice eggs that were immersed in a combination of 10% C. zedoaria EO and 10% E. globulus EO for 5 min did not hatch at all for 7-14 days of incubation. All head lice eggs that were immersed in soyabean oil and drinking water for 1, 5, and 10 min showed 100% hatching rate in 7-14 days of incubation. All head lice eggs that were immersed in permethrin pediculicide for 1, 5 min, showed 100% hatching rate, but when they were immersed for 10 min, permethrin provided 4.0-6.0% inhibition rate with 94.0-96.0% hatching rate for 7-14 days of incubation. All combinations of Zingiberaceae EOs and E. globulus EO at low and high concentrations (5 and 10%) exhibited high ovicidal activities against head lice eggs, and the combinations showed a synergistic effect with an increase in the inhibition rate of more than 50%. CONCLUSION: These results demonstrated that Zingiberaceae EOs augmented with E. globulus EO are promising ovicidal agents for head lice control.

Efficacies of four plant essential oils as larvicide, pupicide and oviposition deterrent agents against dengue fever mosquito,Aedes aegypti Linn. (Diptera: Culicidae)

Objective: To evaluate larvicidal, pupicidal and oviposition deterrent activities of four plant essential oils from Alpinia galanga (L.) Willd rhizome, Anethum graveolens L. (An. graveolens)fruit, Foeniculum vulgare Mill. fruit, and Pimpinella anisum L. fruit against Aedes aegypti (Ae. aegypti). Methods: Four essential oils at 1％, 5％ and 10％ concentrations were assessed for insecticidal activity against larvae and pupae of Ae. aegypti, following the procedure of a dipping method assay. Oviposition deterrent activity of four essential oils was evaluated on gravid female of Ae. aegypti by a dual-choice oviposition bioassay. Results: The results revealed that An. graveolens oil provided the strongest larvicidal activity against Ae. aegypti among four tested plant essential oils with the highest mortality rate of 100％ and LC50 value of -0.3％. From the pupicidal experiment, An. graveolens also showed the highest toxicity against Ae. aegypti pupae with the highest mortality rate of 100％ at 72 h and LC50 value of 2.9％. In addition, 10％ An. graveolens had an oviposition deterrent effect against Ae. aegypti with effective repellency of 100％ and an oviposition activity index of –1.0. Conclusions: An. graveolens oil has a good potential as a larvicidal, pupicidal and oviposition deterrent agent for controlling Ae. aegypti.

New Thai herbal shampoos as pediculicides for killing head louse, Pediculus humanus capitis De Geer (Phthiraptera)

Objective:To evaluate the efficacy of Thai herbal shampoos [Cartoxylum formosum (C.formosum) + eucalyptus essential oil (EO),C.formosum + citrus EO,Solanum trilobatum + eucalyptus EO,Solanum trilobatum + citrus EO,Moringa oleifera + eucalyptus EO and Moringa oleifera + citrus EO] for killing all stages of Pediculus humanus capitis (Phthiraptera).Methods:A filter paper contact method was applied with three concentrations (0.05,0.10 and 0.20 mL/cm2) of each Thai herbal shampoo as well as permethrin pediculicide (positive control) and drinking water (negative control) against eggs,nymphs and adults of Pediculus humanus capitis.Mortality rates of the eggs were recorded after 7 days of incubation while those of nymphs and adults were recorded after 5 minutes of contact.Results:All herbal shampoos at the high concentration were highly effective against nymphs and adults,but not effective against the eggs.C.formosum + eucalyptus EO and C.formosum + citrus EO shampoos at all concentrations exhibited the highest efficacy against nymphs and adults with 100％ mortality rate at 5 min and LC50 values of 0.004 and 0.005 mL/cm2,respectively.All formulation of Solanum trilobatum and Moringa oleifera shampoos added with eucalyptus EO showed mortality rates against nymphs at 92.0％-100.0％ and 76.0％-100.0％ and against adults at 84.0％-100.0％ and 20.0％-32.0％,respectively.Permethrin pediculicide was not effective against the eggs,but showed 68.0％-92.0％ and 28.0％-60.0％ mortality rates against nymphs and adults.Conclusions:These results indicate that C.formosum + eucalyptus EO shampoo can be used as an effective nymphicide and adulticide against Pediculus humanus capitis.

Adulticidal, larvicidal, pupicidal and oviposition deterrent activities of essential oil from Zanthoxylum limonella Alston (Rutaceae) against Aedes aegypti (L.) and Culex quinquefasciatus (Say)

Objective:To evaluate adulticidal,larvicidal and oviposition deterrent response of the essential oil from dried Zanthoxylum limonella (Z.limonella) fruit against Aedes aegypti (Ae.aegypti) and Culex quinquefasciatus (Cx.quinquefasciatus).Methods:Z.limonella oil was tested by biological assays at 1％,5％ and 10％ concentrations in ethanol.Adulticidal efficacy was tested against the 2-3 day old adult females.Larvicidal activity was tested against immature stage of mosquitoes.Oviposition deterrence of the oil was evaluated on gravid females.Results:The adult mortality was observed after 24 h with the LC5o of 6.0％ for Ae.aegypti,and 5.7％ for Cx.quinquefasciatus.Larvicidal bioassay was carried out with the 10％ Z.limonella oil against immature stages of Ae.aegypti and Cx.quinquefasciatus,which caused 100％ mortality after 12 h and 24 h.In the larvicidal experiment,Z.limonella showed effective result at 1％,5％ and 10％ concentrations with the values of LT5o Ae.aegypti =9.78,5.61,0.24 h for larvae and LT5o =64.08,21.23 h for pupae;Cx.quinquefasciatus had LT50 =28.46,20.25,1.01 h for larvae and LT50 =67.52,27.96,4.11 h for pupae,respectively.Oviposition deterrence of the oil was evaluated on gravid females.In the study,10％ Z.limonella showed 100％ repellency for Ae.aegypti and 99.53％ for Cx.quinquefasciatus.Likewise,oviposition activity indexes of these oil concentrations were all negative values ranging from-0.89 to-1.00 for Ae.aegypti and-0.64 to-0.99 for Cx.quinquefasciatus.The oviposition activity indexes values revealed that Z.limonella oil has deterrent effect,and it caused a remarkable negative response resulting in very few eggs.Conclusions:This result indicates that Z.limonella oil can be used as an effective adulticide,larvicide and oviposition deterrent against Ae.aegypti and Cx.quinquefasciatus.

Effect of Cymbopogon citratus (lemongrass) and Syzygium aromaticum (clove) oils on the morphology and mortality of Aedes aegypti and Anopheles dirus larvae.

Cymbopogon citratus (lemongrass) and Syzygium aromaticum (clove) oils were evaluated to determine mortality rates, morphological aberrations, and persistence when used against third and fourth larval instars of Aedes aegypti and Anopheles dirus. The oils were evaluated at 1, 5, and 10 % concentrations in mixtures with soybean oil. Persistence of higher concentrations was measured over a period of 10 days. For Ae. aegypti, both plant oils caused various morphological aberrations to include deformed larvae, incomplete eclosion, white pupae, deformed pupae, dead normal pupae, and incomplete pupal eclosion. All of these aberrations led to larval mortality. In Ae. aegypti larvae, there were no significant differences in mortality at days 1, 5, and 10 or between third and fourth larval instar exposure. In An. dirus, morphological aberrations were rare and S. aromaticum oil was more effective in causing mortality among all larval stages. Both oils were equally effective at producing mortality on days 1, 5, and 10. Both oils had slightly increased LT50 rates from day 1 to day 10. In conclusion, both lemongrass and clove oils have significant effects on the immature stages of Ae. aegypti and An. dirus and could potentially be developed for use as larvicides.

Efficacy of essential oil from Cananga odorata (Lamk.) Hook.f. & Thomson (Annonaceae) against three mosquito species Aedes aegypti (L.), Anopheles dirus (Peyton and Harrison), and Culex quinquefasciatus (Say).

The essential oil of Cananga odorata flowers was evaluated for oviposition-deterrent, ovicidal, insecticidal, and repellent activities toward three mosquito species: Aedes aegypti, Anopheles dirus, and Culex quinquefasciatus. Oviposition deterrence of the oil was evaluated on gravid females using oviposition deterrence bioassay. The results showed that 10 % Ca. odorata exhibited high percent effective repellency against oviposition at 99.4 % to Ae. aegypti, 97.1 % to An. dirus, and 100 % to Cx. quinquefasciatus. Ca. odorata oil was tested for ovicidal activity. Regression equations revealed that the ovicidal rates were positively correlated with the concentrations of the essential oil. As the concentration of essential oil increased from 1, 5, and up to 10 % concentration, the ovicidal rate increased accordingly. Larvicidal activity of the oils was used on immature stages (third and fourth instar lavae and pupae). The maximum larval mortality was found with 10 % Ca. odorata against immature stages, and there were LC50 values ranged from 10.4 to 10.5 % (for Ae. aegypti), <1 % (for An. dirus), and <1 % (for Cx. quinquefasciatus). Adulticidal properties were evaluated with unfed females. Ten percent Ca. odorata oil had high knockdown rates against the three mosquito species at 96 % (for Ae. aegypti), 98.4 % (for An. dirus), and 100 % (for Cx. quinquefasciatus), with EC50 values of 6.2, 4.7, and 5.4 %, respectively. It gave moderate mortality rates after 24 and 48 h of exposure. Ca. odorata oil was assessed for repellency to females by using the modified K&D module. Ten percent Ca. odorata oil gave the strongest value against Ae. aegypti, An. dirus, and Cx. quinquefasciatus, with percentage repellency of 66, 92, and 90 %, respectively. This study demonstrates the potential for the essential oil of Ca. odorata essential oil to be used as a botanical insecticide against three mosquito species.

Efficacy of Thai herbal essential oils as green repellent against mosquito vectors.

Repellency activity of Thai essential oils derived from ylang ylang (Cananga odorata (Lamk.) Hook.f. & Thomson: Annonaceae) and lemongrass (Cymbopogon citratus (DC.) Stapf: Poaceae) were tested against two mosquito vectors, Aedes aegypti (L.) and Culex quinquefasciatus (Say). There were compared with two chemical repellents (DEET 20% w/w; Sketolene Shield(®) and IR3535, ethyl butylacetylaminopropionate 12.5% w/w; Johnson's Baby Clear Lotion Anti-Mosquito(®)). Each herbal repellent was applied in three diluents; coconut oil, soybean oil and olive oil at 0.33 µl/cm(2) on the forearm of volunteers. All herbal repellent exhibited higher repellent activity than IR3535 12.5% w/w, but lower repellent activity than DEET 20% w/w. The C. odorata oil in coconut oil exhibited excellent activity with 98.9% protection from bites of A. aegypti for 88.7±10.4 min. In addition, C. citratus in olive oil showed excellent activity with 98.8% protection from bites of C. quinquefasciatus for 170.0±9.0 min. While, DEET 20% w/w gave protection for 155.0±7.1-182.0±12.2 min and 98.5% protection from bites of two mosquito species. However, all herbal repellent provided lower repellency activity (97.4-98.9% protection for 10.5-88.7 min) against A. aegypti than C. quinquefasciatus (98.3-99.2% protection for 60-170 min). Our data exhibited that C. odorata oil and C. citratus oil are suitable to be used as green repellents for mosquito control, which are safe for humans, domestic animals and environmental friendly.

Repellency of essential oils extracted from Thai native plants against Aedes aegypti (Linn.) and Culex quinquefasciatus (Say).

Repellent activity of essential oils derived from 10 Thai native plants, belonging to three families were evaluated against female Aedes aegypti and Culex quinquefasciatus and to compare them with a commercial chemical repellents (DEET; N,N-diethyl-3-methylbenzamide 20% w/w; Sketolene Shield). Each test repellent was applied at 1, 5, and 10% concentrations for testing by arm in cage method. The results showed significant differences in repellency among the repellents by mosquito species. The protection time of the essential oils against Ae. aegypti ranged from 3 to 30 min. According to the Culex mosquito, it showed the protection time ranged from 3 to 260 min. 10 % Boesenbergia rotunda essential oil provided the best efficiency, in which protection time was 4.3 h as equal as DEET. The essential oils which exhibited protection time more than 2 h were those of 10% Zingiber zerumbet, Litsea petiolata, Curcuma zedoaria, and Zingiber cassumunar essential oils (3.1, 2.8, 2.6, and 2.3 h, respectively). The biting percentage ranged from 0.9 to 18.0% and 0.8 to 3.6% against Ae. aegypti and Cx. quinquefasciatus, respectively. The results revealed that the potential of essential oil extracted from B. rotunda, Z. zerumbet, L. petiolata, C. zedoaria, and Z. cassumunar had attributes of good repellent and deterred biting. We recommend the five essential oils for further study to develop as commercial repellents.

Efficacy of herbal shampoo base on native plant against head lice (Pediculus humanus capitis De Geer, Pediculidae: Phthiraptera) in vitro and in vivo in Thailand.

Head lice infestation (or pediculosis) is an important public health problem in Thailand, especially in children between the ages 5 and 11 years. Head lice resistance is increasing, chemical pediculicides have lost their efficacy, and, therefore, alternative pediculicides such as herbal shampoos have been proposed to treat head lice infestation. Thus, the present study investigated the efficacy of three herbal shampoos based on native plants in Thailand (Acorus calamus Linn., Phyllanthus emblica Linn., and Zanthoxylum limonella Alston) against head lice and compared them with carbaryl shampoo (Hafif shampoo, 0.6% w/v carbaryl), malathion shampoo (A-Lice shampoo, 1.0% w/v malathion), and commercial shampoos (Babi Mild Natural' N Mild and Johnson's baby shampoo) in order to assess their in vitro and in vivo efficacy. For in vitro study, doses of 0.12 and 0.25 ml/cm(2) of each herbal shampoo were applied to filter paper, then 10 head lice were place on the filter paper. The mortalities of head lice were recorded at 5, 15, 30, and 60 min. The results revealed that all herbal shampoo were more effective on pediculicidal activity than chemical and commercial shampoos with 100% mortality at 15 min; LT50 values ranged from 0.25 to 1.90 min. Meanwhile, chemical shampoos caused 20-80% mortality, and LT50 values ranged from 6.50 to 85.43 min. On the other side, commercial shampoos showed 4.0% mortality. The most effective pediculicide was Z. limonella shampoo, followed by A. calamus shampoo, P. emblica shampoo, carbaryl shampoo, malathion shampoo, and commercial shampoo, respectively. In vivo results showed that all herbal shampoos were also more effective for head lice treatment than chemical and commercial shampoos with 94.67-97.68% of cure rate after the first treatment; the second treatment, 7 days later, revealed that the cure rate was 100%. Meanwhile, chemical shampoo showed 71.67-93.0% of cure rate and, unfortunately, commercial shampoos were nontoxic to head lice and showed 0% of cure rate after the first and the second treatments. Our data showed that three herbal shampoos of native plants in Thailand in this study are suitable to be used as pediculicides for Thai children since it is safe for children and there is no side-effect after application.

Oviposition deterrent and ovicidal activities of seven herbal essential oils against female adults of housefly, Musca domestica L.

The oviposition deterrent and ovicidal of seven herbal essential oils derived from Citrus sinensis, Cymbopogon citratus, Eucalyptus glubulus, Illicium verum, Lavandula angustifolia, Mentha piperita, and Zingiber cussumunar were assessed against the gravid female of housefly, Musca domestica L., under laboratory conditions and compared with commercial insecticide (10% w/v cypermethrin). They were assayed at three concentrations (1.0, 5.0, and 10.0%) where plastic cups containing 1 ml of desired oil concentration and cotton pad soaked with 10 ml of milk solution (10% w/v) were used as oviposition substrate. The 0.1 ml of deferent concentrations was dropped on ten housefly eggs, which were used for ovicidal activity. The number of eggs laid and the hatched larvae in each cup was recorded to evaluate the oviposition deterrent and ovicidal activities of the herbal essential oils. High concentration (10%) of herbal essential oils showed high percent effective repellency (ER). The 10% I. verum oil caused complete oviposition deterrence (100% ER, oviposition activity index (OAI) = -1.0), followed by Z. cussumunar, M. piperita, L. angustifolia, C. citratus, C. sinensis, and E. glubulus oils with 97.20, 88.55, 88.14, 87.93, 76.68, and 57.00% ER, respectively. As the concentration of herbal essential oils increased from 1.0, 5.0, and up to 10.0% concentration, the hatching rate decreased. Ten percent I. verum oil gave the maximum inhibiting rate at 97.3% (LC50 value of 6.85%); in addition, the other herbal essential oils showed the minimum inhibiting rate of 3.3-22.7%. On the other hand, cypermethrin 10% w/v showed complete oviposition deterrence (100% ER, OAI = -1.0) and ovicidal activity (100% inhibiting rate). Our data showed that I. verum oil have high potential of oviposition deterrence and ovicide housefly control.

Efficacy of herbal essential oils as insecticides against the housefly, Musca domestica L.

The insecticidal effects of 20 essential oils derived from herbs, were tested against the housefly species Musca domestica L. using a susceptibility test. Each was applied in ethyl alcohol at concentrations of 1, 5 and 10% (v/v). Ten percent concentrations of Cymbopogon citratus (lemongrass), Mentha piperita (peppermint) and Lavandula angustifolia (lavender) oils were the most effective, showing 100% knockdown at 30 and 60 minutes. The KT50 values for C. citratus, M. piperita and L. angustifolia were 5.14, 5.36 and 8.23 minutes, respectively. These essential oils caused 100% mortality among houseflies 24 hours after exposure. The LC50 values for C. citratus, M. piperita and L. angustifolia were 2.22, 2.62 and 3.26 minutes, respectively. This study reveals lemongrass, peppermint and lavender essential oils have the potential to control housefly populations and should be further studied for field applications.

In vitro pediculicidal activity of herbal shampoo base on Thai local plants against head louse (Pediculus humanus capitis De Geer).

Head lice infestation, a worldwide head infestation caused Pediculus humanus capitis De Geer, is an important public health problem in Thailand. Several chemical pediculicides have lost in efficacy due to increasing resistance of lice against insecticide. Therefore, non-toxic alternative products, such as natural products from plants, e.g. plant extract pediculicides, are needed for head lice control. The aims of this study were to evaluate the potential of pediculicidal activity of herbal shampoo base on three species of Thai local plants (Accacia concinna (Willd.) DC, Averrhoa bilimbi Linn. and Tamarindus indica Linn.) against head lice and to compare them with carbaryl shampoo (Hafif shampoo®; 0.6% w/v carbaryl) and non-treatment control in order to assess their in vitro. Doses of 0.12 and 0.25 ml/cm2 of each herbal shampoo were applied to filter paper, and ten head lice were place on the filter paper. The mortalities of head lice on the filter paper were recorded at 1, 5, 10, 30 and 60 min by sterio-microscope. All herbal shampoos at 0.25 ml/cm2 were more effective pediculicide than carbaryl shampoo with 100% mortality at 5 min. The median lethal time (LT50) of all herbal shampoos at 0.25 ml/cm2 showed no significant differences over at 0.12 ml/cm2 (P<0.01). The most effective pediculicide was T. indica extract shampoo, followed by Av. bilimbi extract shampoo and Ac. concinna extract shampoo, with LT50 values<1.0 min. Our data showed that all herbal shampoos have high potential of pediculicide to head lice treatments for schoolchildren.