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Synergistic Larvicidal and Pupicidal Effects of Monoterpene Mixtures Against Aedes aegypti with Low Toxicity to Guppies and Honeybees
(2025-07-01)
Sittichok, Sirawut
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Passara, Hataichanok
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Moungthipmalai, Tanapoom
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Sinthusiri, Jirisuda
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Murata, Kouhei
The present study evaluated the larvicidal and pupicidal activities of pure and mixed monoterpene formulations—eucalyptol, geranial, trans-anethole, and trans-cinnamaldehyde—against Aedes aegypti and compared them with 1% (w/w) temephos. Safety bioassays of all formulations on non-target species confirmed their safety. The combined mixture of eucalyptol + trans-anethole at 400 µg/mL exhibited stronger larvicidal activity, with an LC<inf>50</inf> of 176 µg/mL, while the combination of trans-anethole + geranial at 400 µg/mL exhibited stronger pupicidal activity with an LC<inf>50</inf> of 167 µg/mL. Both formulations were more effective than a 1% temephos. All the mixture formulations were more strongly synergistic compared to pure formulations, with an increased mortality value (IMV) of 25% to 95%. External morphological aberrations observed at death included swelling of the respiratory system. Importantly, all the formulations were safe for two non-target species: guppies (Poecilia reticulata) and honeybees (Apis mellifera). The combination formulations are strong larvicides and pupicides for controlling Ae. Aegypti, which will help reduce the spread of viruses carried by this vector.
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Larvicidal and pupicidal activity of combination of two plant essential oils against Aedes aegypti
(2025-01-01)
Sinthusiri, J.
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Puwanard, C.
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Passara, H.
;
Soonwera, M.
The larvicidal and pupicidal effects of six mixtures of cinnamon (Cinnamomum verum J. Presl.) and nutmeg (Myristica fragrans Houtt.) essential oils (EOs) and major compositions (geranial, α-pinene and trans- cinnamaldehyde) were tested against early fourth instar and pupal stages of Aedes aegypti. The combinations (2% cinnamon EO + 1% geranial, 2% cinnamon EO + 1% trans-cinnamaldehyde and 2% cinnamon EO + 1% α-pinene) showed high toxicity against early 4th instar larvae, with 100% mortalities at 24 hours and LT50 between 1.4 and 2.4 hours. Additionally, 2% nutmeg EO + 1% α-pinene showed >99% mortality at 24 hours with LT50 = 4.6 hours. 2% nutmeg EO + 1% geranial and 2% nutmeg EO + 1% α-pinene were highly toxic against pupae, with 100% mortality at 48 hours and LT50 values of 5.8 and 7.8 hours. On the other hand, temephos showed LT50 for larval and pupal stages at 9.8 and 94.1 hours. It showed that 2% nutmeg EO + 1% α-pinene was able to control immature stages and was more effective than temephos. However nutmeg extracts need to be checked for human and valuable species toxicity.
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Synergistic Larvicidal and Pupicidal Toxicity and the Morphological Impact of the Dengue Vector (Aedes aegypti) Induced by Geranial and trans-Cinnamaldehyde
(2024-09-01)
Sittichok, Sirawut
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Passara, Hataichanok
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Sinthusiri, Jirisuda
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Moungthipmalai, Tanapoom
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Puwanard, Cheepchanok
Monoterpenes are effective and eco-friendly alternatives to conventional chemical larvicides. We tested single and binary mixtures of monoterpenes—geranial and trans-cinnamaldehyde—for their larvicidal and pupicidal activities against Aedes aegypti L. and for non-target toxicity on guppies (Poecilia reticulata Peters), using 1% (w/w) temephos as a reference. Geranial and trans-cinnamaldehyde at 250 ppm showed stronger larvicidal and pupicidal activities with a 100% mortality rate and an LT<inf>50</inf> ranging from 0.3 to 0.6 h. All combinations were strongly synergistic against larvae and pupae compared to single formulations, with an increased mortality value (IMV) of 6% to 93%. The combination of geranial + trans-cinnamaldehyde (1:1) at 200 ppm showed the highest impact, with an IMV of 93%. The strongest larvicidal and pupicidal activities, a 100% mortality rate, and an LT<inf>50</inf> of 0.2 h were achieved by geranial + trans-cinnamaldehyde (1:1) 500 ppm. They were thirty times more effective than a 1% temephos solution (LT<inf>50</inf> ranging from 6.7 to 96 h) and caused obviously shriveled cuticles and a swollen respiratory system. All single and binary mixtures were not toxic to the guppies. Thus, the combination of geranial + trans-cinnamaldehyde has great potential as a safe insecticide for controlling mosquito larvae and pupae.
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Toxicity of Litsea petiolata Hook.f. essential oil against Aedes aegypti (Linn.), Aedes albopictus (Skuse), Anopheles minimus (Theobald) and Culex quinquefasciatus (Say)
(2022-09-01)
Puwanard, C.
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Moungthipmalai, T.
;
Soonwera, M.
This study evaluated the oviposition deterrent, ovicidal, larvicidal, pupicidal, and adulticidal activities of essential oil (EO) from Litsea petiolata leaves against Aedes aegypti, Aedes albopictus, Anopheles minimus and Culex quinquefasciatus with double choice, dipping, and contact assays. Litsea petiolata EO was tested at 1, 5, and 10% concentrations in ethanol and their efficiencies were compared with those of 1% w/w temephos and 10 % w/v cypermethrin. Oviposition deterrent was evaluated on gravid females. Larvicidal and pupicidal activities were tested on the fourth larvae and 2-day-old pupae. The adulticidal activity was tested against two-day-old adult females. Ten percent of L. petiolata EO exhibited the highest oviposition deterrent activity against gravid females and 100% repellency against Ae. albopictus and An. minimus, 97.0% against Ae. aegypti and 94.6% against Cx. quinquefasciatus. The oviposition activity index (OAI) against females of those four mosquito species ranged from -0.9 to -1.0. Ten percent of L. petiolata EO also exhibited the highest ovicidal activity against the eggs of the four mosquito species, with an inhibition rate ranging from 87.2 to 100%. Moreover, it also showed the highest larvicidal and puicidal activities against the larvae and pupae of the four mosquito species, with a 100% mortality rate at 10 and 60 min, respectively. The adulticidal activity was recorded at 1 and 24h. Ten percent of L. petiolata EO exhibited the highest toxicity to female adults of the four mosquito species, with 100% knockdown (1h) and mortality (24h) rates. On the other hand, 1%w/w temephos did not deter gravid females, and it was only slightly toxic to the eggs and larvae and non-toxic to the pupae. In the same manner, 10%w/v cypermethrin was less effective against the female adults of the four mosquito species than 10% L.petiolata EO. L.petiolata EO is a highly effective and eco-friendly alternative to synthetic insecticides.
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Combinations of plant essential oils and their major compositions inducing mortality and morphological abnormality of Aedes aegypti and Aedes albopictus
(2022-05-01)
Soonwera, Mayura
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Moungthipmalai, Tanapoom
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Aungtikun, Jirapon
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Sittichok, Sirawut
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 LT<inf>50</inf> ranging from 0.2-6.9 h. Between the two tested constituents, trans-anethole exhibited stronger larvicidal and pupicidal activities (LC<inf>50</inf> ranging 2.4–3.4%) against the two tested mosquito species than d-limonene (LC<inf>50</inf> 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 (LT<inf>50</inf> ranging 0.1–0.3 h) than 1% (w/w) temephos (LT<inf>50</inf> 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.
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Ovicidal and adulticidal activities of Cymbopogon citratus (DC.) Stapf and Illicium verum Hook. f. against Aedes aegypti (Linn.)
(2022-01-01)
Puwanard, C.
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Soonwera, M.
The hatching inhibition and knockdown rates against Aedes aegypti of two essential oils (EOs): Cymbopogon citratus DC. Stapf and Illicium verum Hook F was evaluated. The efficacy of each of these EOs, at 1, 5, 10% emulsion in water, stabilized by tween 60®, was compared to that of 1% w/v temephos and 1% w/w cypermethrin (common, harmful synthetic insecticides). Topical and contact assays showed that 10% C. citratus and 10% I. verum emulsions were the most effective in inhibiting the hatching of mosquito eggs (100%) after 48 hours of exposure. Moreover, they were also the most toxic against mosquito adults (100% mortality) after 24 hours of exposure. This study also established that tween 60® had no effect on hatching inhibition or mortality rate of treated Aedes aegypti mosquitoes. All EO emulsions were more potent than temephos and cypermethrin against these mosquito species. Coupling this higher efficacy with no or benign known side effects of natural EOs, it can be concluded that 10% C. citratus and 10% I. verum emulsions are better alternatives than temephos and cypermethrin for a mosquito control program at the present time.
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Entomological risk assessment for dengue virus transmission during 2016–2020 in kamphaeng phet, thailand
(2021-10-01)
Fansiri, Thanyalak
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Buddhari, Darunee
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Pathawong, Nattaphol
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Pongsiri, Arissara
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Klungthong, Chonticha
Individual houses with high risks of dengue virus (DENV) transmission might be a source of virus transmission within the neighborhood. We conducted an entomological risk assessment for DENV transmission at the household level, comprising family cohort members residing in the same location, to assess the risk for dengue virus transmitted by mosquito vectors. The studies were conducted in Kamphaeng Phet Province, Thailand, during 2016–2020. Entomological investigations were performed in 35 cohort families on day 1 and day 14 after receiving dengue case reports. DENV was found in 22 Aedes samples (4.9%) out of 451 tested samples. A significantly higher DENV infection rate was detected in vectors collected on day 1 (6.64%) compared to those collected on day 14 (1.82%). Annual vector surveillance was carried out in 732 houses, with 1002 traps catching 3653 Aedes females. The majority of the 13,228 water containers examined were made from plastic and clay, with used tires serving as a primary container, with 59.55% larval abundance. Larval indices, as indicators of dengue epidemics and to evaluate disease and vector control approaches, were calculated. As a result, high values of larval indices indicated the considerably high risk of dengue transmission in these communities.
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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.)
(2020-06-01)
Soonwera, Mayura
;
Sittichok, Sirawut
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.
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Effect of Cymbopogon citratus (lemongrass) and Syzygium aromaticum (clove) oils on the morphology and mortality of Aedes aegypti and Anopheles dirus larvae
(2016-04-01)
Soonwera, Mayura
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Phasomkusolsil, Siriporn
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 LT<inf>50</inf> 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.
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SIR transmission model of dengue virus taking into account two species of mosquitoes and an age structure in the human population
(2015-07-28)
Sungchasit, R.
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Pongsumpun, P.
;
Tang, I. M.
Dengue is a vector-borne disease. It is transmitted to humans by the bites of the Aedes aegypti and Aedes albopictus mosquitoes. The human population is separated into two classes, a child class and an adult class, each class being described by a SIR model. The transmission rates of the two mosquito species are different and depend on what class the humans belong to. We develop a single model taking into account the presence of two type of mosquitoes and two age classes and apply it to dengue fever. The model shows how it is possible for the maximum level of infected human to be reached in a short time. The nature of stability of the equilibrium state and the trajectories of the individual classes in the model are determined by the values of the basic reproduction number by setting the values of the parameters in the model to different values which reflect the environment in which the epidemic is occurring in the model.

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