Synthetic Larvicides Research Articles

Larvicidal activity of terpenes and their derivatives against Aedes aegypti: a systematic review and meta-analysis.

Aedes aegypti (Diptera: Culicidae) is the primary arthropod vector responsible for the transmission of dengue, which is present in more than one hundred countries. The application of synthetic larvicides is one of the most common strategies used for dengue control, but their prolonged use can cause larvicide resistance or tolerance, environmental damage, and have toxic effects on human and animal health. Thus, faced with this problem, there have been increasing efforts to find alternative larvicides against Ae. Aegypti. This search has been mainly focused on naturally occurring chemical compounds, driven by the evidence of their potential effectiveness, and by a desire to find more sustainable, environmentally friendly, and safe alternatives to synthetic larvicides. Thus, the present study aimed to review the effects of terpenes and their derivatives on mortality of the Ae. aegypti larvae, focusing mainly on a lethal concentration of 50% (LC50), in addition to summarizing information on its mechanisms of action and effects on non-target organisms. We searched the main databases for studies published up to April 2024 using relevant keywords, and data were extracted and analyzed qualitatively and quantitatively. Twenty-one articles describing 69 different terpenes and derivatives met the criteria of the review and meta-analysis. Among them, 76.8% were terpenoids and 23.2% terpenes. The LC50 ranged from 0.4 to 1628.2ppm. The present review and meta-analysis showed that the terpenes and terpenoids can be promising chemical templates for use in eco-friendly larvicides against Ae. aegypti.

Larvicidal activity of liverworts’ (Marchantia paleacea) ethyl acetate fraction against Athalia proxima

Abstract Indonesia is an agrarian country with extensive agricultural land and a variety of crop types. One of the challenges faced by farmers when cultivating crops is pest infestation. The larval stage of Athalia proxima attacks cruciferous plants, leading to a 65-80% decrease in productivity. Continuous use of synthetic larvicides has negative impacts such as pest resistance, harm to natural plant enemies, and environmental pollution. This research aims to investigate the larvicidal activity of the ethyl acetate fraction of ethanol extract from liverworts (Marchantia paleacea) against A. proxima. The stages of compound isolation included extraction and fractionation. Compound groups in the fraction were identified through phytochemical screening. The larvicidal activity testing method used was the spray method. The concentrations of liverwort ethyl acetate fraction used were 0.4%, 0.6%, 0.8%, and 1%. Distilled water was used as a negative control. Larval mortality was observed 24 hours after application and analyzed using probit analysis to determine the LC50 value. Phytochemical screening results indicated that the ethyl acetate fraction tested positive for alkaloids, phenolics, flavonoids, terpenoids, and steroids. The LC50 value of the ethyl acetate fraction of the ethanol extract from M. paleacea was 0.33%. Therefore, the ethyl acetate fraction of M. paleacea exhibited high larvicidal activity against A. proxima.

Toxicity Test of Red-Shoot Leaves (Syzygium myrtifolium Walp.) Extract as Biolarvicide on Filariasis Vector Mortality

The Control of Culex sp. using synthetic larvicides is harmful to the environment and human health. Biolarvicide from red shoot leaves (Syzygium myrtifolium) is a safe alternative for the environment and human health. This study aims to determine the effect of Syzygium myrtifolium leaves extract with ethanol solvent and water solvent on larval mortality and the LC50 values of these extracts. ANOVA test results (α = 0.05) on the mortality of Culex sp. larvae exposed to the ethanol extract and aqueous extract of S. myrtifolium leaves consecutively showed F-calculated (287)>F-tabulated (3,11) and F-calculated (153)>F-tabulated (3, 11). The treatment of S. myrtifolium leaves extract with ethanol and water solvents had a significant effect on the mortality of Culex sp. larvae. The LC50 value of the ethanol extract and the aqueous extract of S. myrtifolium leaves are 1659 ppm and was 2053.7 ppm. It can be concluded that S. myrtifolium leaves extracts with ethanol solvent and water solvent have an effect on the mortality of Culex sp. larvae, but are not yet effective as biolarvicide

Larvicides Activity of Krokot Extract into Aedes aegypti Mortality

Dengue Hemorrhagic Fever (DHF) is transmitted by Aedes aegypti, one of controlling vectors which is larvicides. Synthetic larvicides cause several problems so that alternative natural larvicides are used. One of which is the krokot (Portulaca oleracea, L.), the content such as flavonoids, tannins, alkaloids, and saponins can be used as larvicides. This study aims to determine the larvicides activity of krokot extract on mortality of Aedes aegypti. The study was conducted using experimental quantitative research. The study was conducted by pouring the ethanol extract on 25 larvae and repeated 3 times, for 24 hours. The result of larvae mortality test at concentrations of 4%, 5% and 6%, namely 39%, 57% dan 72%. LC50 value from krokot extract on the larvae mortality, that is equal to 9.294%. Based on the study, it can be concluded that the krokot ethanol extract is able to kill 50% of the Aedes aegypti larvae population. Keywords: krokot, ethanol extract, Aedes aegypti, mortality

Biolarvicide activity of extract and essential oil of culantro (Eryngium foetidum L.) on Culex quinquefasciatus larvae in silico and in vitro


 
 
 
 Background: Filariasis, a priority tropical disease in Indonesia, is transmitted by the Culex quinquefasciatus mosquito. The use of conventional synthetic larvicides can lead to environmental and health issues, including poisoning and resistance in target insect populations.
 Objective: This study explores the utilization of biolarvicides derived from culantro (Eryngium foetidum) to mitigate these adverse efects, focusing on analyzing the components and evaluating the larvicidal eficacy of both the extract and essential oil of E. foetidum.
 Method: This study employed a molecular docking approach to examine in silico biolarvicidal activity against the odorant binding protein (OBP) receptor and conducted in vitro experiments on Cx. quinquefasciatus larvae using varying concentrations of E. foetidum extract (100, 250, and 500 ppm) and essential oil (10, 50, and 100 ppm).
 Results: The in silico study identified hynokiflavone and longifenaldehyde as the compounds with the most potent activity, demonstrating binding a inities of -10.2 and -9.5 kcal/mol, respectively. The in vitro assays revealed that the E. foetidum extract achieved 75% larval mortality at an LC50 of 78.59 ppm, while the essential oil resulted in 88% mortality with an LC50 of 10.13 ppm.
 Conclusion:The extract and essential oil of E. foetidum exhibit significant biolarvicidal activity against Culex quinquefasciatus, offering promising plant-based alternatives to traditional larvicides, with implications for safer and more sustainable vector control strategies.
 
 
 

Effectivity test of ethanol extract of black pepper (Piper nigrum) against mortality of Aedes aegypti and its effect on midgut morphological changes

Aedes aegypti is the vector of Dengue Hemorrhagic Fever (DHF). Dengue vector management usually depends on synthetic larvicides. However, it can lead to insect resistance and leave chemical pollutant residues. Therefore natural larvicides are needed for their environmentally friendly and do not induce insect resistance. Piper nigrum fruit is expected to contain secondary metabolites beneficial as larvicides to Aedes aegypti. This study aims to test the effectivity of the ethanol extract of Piper nigrum fruit on the mortality of Aedes aegypti larvae and determine the effect of extract exposure on larval midgut morphological changes. The study used a completely randomized design with five experimental groups and four repetitions as follows: K (aquades + 0% extract), P1 (0.25% extract), P2 (0.50% extract), P3 (0.75% extract), P4 (1% extract). Data analysis used one-way ANOVA and continued to the LSD Post hoc test. The extract's effectiveness was analyzed using the probit test and LC50 confirmation. Changes in the morphology of larval midgut were observed descriptively and presented in the form of tables and figures. The results showed that the 1% treatment resulted in the highest larval mortality of 93% and the lowest in the 0.25% treatment of 43%. The LC50 value was 2,666 based on the probit analysis. The ethanol extract of Piper nigrum fruit affected midgut morphological changes of Aedes aegypti larvae characterized by peripheral membrane damage, microvilli thinning, epithelial cell swelling and vacuolation, and basement membrane damage.

Phytochemicals and Larvicidal Activity of Sonneratia alba Root Extracts from Ngurah Rai Mangrove Forest, Denpasar-Bali

Dengue is an endemic disease with a high incidence in almost all Southeast Asian countries, including Indonesia. This infectious disease is caused by a virus transmitted by the bite of Aedes aegypti mosquito as the main vector. Effective mosquito vector control is a crucial step in stopping the spread of this virus. Of the several methods available, the use of larvicides is considered one of the most successful treatments in reducing the number of mosquito vectors. However, widely used synthetic larvicides can have undesirable side effects on the environment and non-target organisms including human health. The aim of this study was to discover a new biolarvicide from natural materials that is relatively safer. In this study, the biolarvicidal activity of mangrove plant species that are commonly found in Ngurah Rai Mangrove Forest Bali was tested, namely Sonneratia alba. Mangrove root simplicia was extracted by reflux method using three different solvents namely methanol, chloroform, and n-hexane. The content of compounds in the extract were analyzed using GC/MS method. The larvicidal activity of the extracts were tested on A. aegypti instar III/IV larvae with concentrations of 0.1, 1, 10, 100, and 1000 ppm for 24 hours. Subsequently, the average value of larval mortality was used to calculate the LC50 of each extract. The results showed that S. alba methanol extract provided the best larvicidal activity compared to chloroform and n-hexane extracts, with mortality of 69.33% at a concentration of 1000 ppm and LC50 of 1265 ppm. GC-MS analysis showed that the methanol extract of S. alba contained five dominant compounds namely Methyl 2-hydroxy-eicosanoate (19.55%); 4H-1-Benzopyran-4-one, 3,5-dihydroxy-2-(4-hydroxy-3-methoxyphenyl)-7-methoxy (16.48%); 4-((1E)-3-Hydroxy-1-propenyl)-2-methoxyphenol (10.06%); Benzamide, N-[4-(2-naphtyl)-2-thiazolyl]- (9.40%); and 2,3-Dihydro-3,5-bis(3-methoxyphenyl)-1H-inden-1-one (6.52%). The results of this study provide a preliminary result on larvicide activity from mangrove S. alba in order to develop bio larvicides from nature which is safer for human health and environment.

Chemical composition, larvicidal and molluscicidal activity of the essential oil Alpinia zerumbet

In this present study, we describe the chemical composition, larvicidal and molluscicidal activity of essential oil distilled from Alpinia zerumbet leaves against third-stage larvae of Ae.aegypti and the snail Biomphalaria glabrata, respectively. For this, we distilled the oil by hydrodistillation, identified its components by gas chromatography coupled to mass spectrometry and gas chromatography with flame ionization detection and calculated the lethal concentration of larvicidal and molluscicidal activity using the probit method. From these analyses, we showed that the oil is predominantly composed of monoterpenes, in which p-cymene (34.12%), 1,8-cineole (25.67%) and terpinen-4-ol (21.01%) stood out. In addition, we also proved that the oil has larvicidal and molluscicidal activity with lethal concentrations respectively of 43.74 and 36.52 μg/mL. Therefore, we conclude that the oil is active and has the potential to replace synthetic larvicides and molluscicides.

Test The Effectiveness Of Japanese Papaya Leaf Extract (Cnidoscolus aconitifolius) On Aedes aegypti Larvae Mortality

Dengue hemorrhagic fever (DHF) is caused by the dengue virus which is transmitted through the bite of the Aedes aegypti mosquito. Prevention of DHF can be done by using larvicides. Synthetic chemical larvicides are considered to have side effects in long-term use and can cause environmental pollution. So we need an alternative larvicides with natural ingredients from plants, namely Japanese Papaya plants. This study aims to determine the effectiveness of Japanese Papaya (Cnidoscolus aconitifolius) leaf extract on the mortality of Aedes aegypti larvae. This type of research uses an experimental study design. This study used 6 treatments with 4 repetitions consisting of control without treatment, P1 (0.2%), P2 (0.4%), P3 (0.6%), P4 (0.8%), and P5 (1%). Observations were made for 48 hours. From the research results obtained LC50 of 1.095%. The results of statistical tests using One-Way ANOVA showed that there was a significant effect on the mortality of mosquito larvae.

Optimised neem oil-bilayer tablets: A safe, effective and stable tool for the prevention of vector-borne disease outbreaks by Aedes albopictus

The control of mosquito breeding is an essential step towards the reduction of vector-borne disease outbreaks. Synthetic larvicidal agents produce resistance in vectors and cause safety concerns in humans, animals and aquatic species. The drawback of synthetic larvicides opened a new avenue for natural larvicidal agents, but poor dosage accuracy, need for frequent applications, low stability and sustainability are the major challenges with them. Hence, this investigation aimed to overcome those drawbacks by developing bilayer tablets loaded with neem oil to prevent mosquito breeding in stagnant water. The optimised batch of neem oil-bilayer tablets (ONBT) had 65%w/w hydroxypropyl methylcellulose K100M and 80%w/w ethylcellulose in its composition. After the completion of 4th week, 91.98 ± 0.871% azadirachtin was released from the ONBT, which was followed by a subsequent drop in the in vitro release. ONBT reported long-term larvicidal efficacy (>75%) and a good deterrent effect which was better than neem oil-based marketed products. The acute toxicity study on a non-target fish model (Poecilia reticulata), OECD Test No.203 confirmed the safety of the ONBT on non-target aquatic species. The accelerated stability studies predicted a good stability profile for the ONBT. The neem oil-based bilayer tablets can be used as an effective tool for the control of vector-borne diseases in society. The product may be a safe, effective and eco-friendly replacement for the existing synthetic as well as natural products in the market.

Evaluating the Sublethal Effects of Origanum vulgare Essential Oil and Carvacrol on the Biological Characteristics of Culex pipiens biotype molestus (Diptera: Culicidae).

Culex pipiens is a mosquito species complex spread worldwide that poses a serious threat to human health as the primary vector of West Nile virus. Its control is mainly based on larvicidal applications with synthetic insecticides on mosquito breeding sites. However, the excessive use of synthetic larvicides may provoke mosquito resistance issues and negative side effects to the aquatic environment and human health. Plant-derived essential oils, including those from the Lamiaceae family, can be eco-friendly alternative larvicidal agents causing acute larval toxicity and/or growth inhibitory effects on the developmental stages of mosquitoes through different modes of action. In the current laboratory study, we evaluated the sublethal effects of carvacrol-rich oregano essential oil and pure carvacrol on Cx. pipiens biotype molestus, the autogenous member of the Cx. pipiens species complex, after the exposure of 3rd-4th instar larvae to LC50 concentrations. The short-term (24 h) larvicidal treatment with the sublethal concentrations of both tested materials exhibited an acute lethal effect on the exposed larvae as well as significant delayed mortality for surviving larvae and pupae. Larvicidal treatment with carvacrol reduced the longevity of the emerged males. In addition, the morphological abnormalities that were observed at the larval and pupal stage along with failed adult emergence indicate the potential growth inhibitory properties of the tested bioinsecticides. Our findings suggest that carvacrol and carvacrol-rich oregano oil are effective plant-based larvicides at doses lower than the acute lethal ones, thus promoting an environmentally friendly and more affordable perspective for their use against the WNV vector Cx. pipiens biotype molestus.

Chemical ecology of Himalayan eggplant variety's antixenosis: identification of geraniol as an oviposition deterrent against the eggplant shoot and fruit borer.

Eggplant (Solanum melongena) suffers severe losses due to a multi-insecticide-resistant lepidopteran pest, shoot and fruit borer (SFB, Leucinodes orbonalis). Heavy and combinatorial application of pesticides for SFB control renders eggplant risky for human consumption. We observed that gravid SFB females do not oviposit on Himalayan eggplant variety RC-RL-22 (RL22). We hypothesized that RL22 contained an antixenosis factor. Females' behavior indicated that the RL22 cue they perceived was olfactory. To identify it, leaf volatile blends of seven eggplant varieties were profiled using solid phase microextraction and gas chromatography mass spectrometry. Seven RL22-specific compounds were detected in the plant headspace. In choice assays, oviposition deterrence efficacies of these candidate compounds were independently tested by their foliar application on SFB-susceptible varieties. Complementation of geraniol, which was exclusively found in RL22, reduced oviposition (> 90%). To validate geraniol's role in RL22's SFB-deterrence, we characterized RL22's geraniol synthase and silenced its gene in planta, using virus-induced gene silencing. Geraniol biosynthesis suppression rendered RL22 SFB-susceptible; foliar geraniol application on the geraniol synthase-silenced plants restored oviposition deterrence. We infer that geraniol is RL22's SFB oviposition deterrent. The use of natural compounds like geraniol, which influence the chemical ecology of oviposition, can reduce the load of hazardous synthetic larvicides.

INSECTICIDAL EFFECTS OF ETHANOLIC LEAF EXTRACT OF MILLINGTONIA HORTENSIS L.F. (BIGNONIACEAE) AGAINST AEDES AEGYPTI (DIPTERA: CULICIDAE)

Mosquitoes are the most important group of insects in terms of public health importance, which transmit seriousdiseases. Vector control is a major challenge now a-days when they became resistance against commonly availableinsecticides and an adverse effect on non-target organisms and environment. Plants are potential source of bioactiveagents which can be used in vector control and phytochemicals may serve as appropriate alternative to syntheticinsecticides. The present work evaluated the mosquito larvicidal, pupicidal potential of ethanol leaf extract of Millingtoniahortensis against the larval (I-IV) and pupal stages of Aedes aegypti. The larvicidal and pupicidal assay test are carried out theinstructions of WHO guidelines. The data were subjected to Finney’s method of probit analysis. The LC50,90 /24,48hours values of ethanol leaf extract of M. hortensis to I instar larvae was 0.032 0.038; 0.021 0.031 % and this was found togradually increase with the age of larvae. Pupae showed the highest resistance to the ethanol leaf extract of M. hortensis asevident from the relatively higher LC50,90 /24,48 hours values 0.068, 0.071; 0059, 0.069 %. Therefore, ethanolic leafextract of M. hortensis can be used as alternative to synthetic larvicides and it may become an important tool in mosquitocontrol programs.

Potential of Leaf Extracts Sonneratia alba and Avicennia alba as a Biolarvacide of Aedes aegypti Mosquito

The continuous use of synthetic larvacides as an effort to control the vector mosquito population of Dengue Hemorrhagic Fever (DHF) can cause negative impacts on the environment and humans. Bioactive compounds from animals and plants can be used as an alternative to natural larvacides (biolarvacides). Mangrove species Sonneratia alba and Avicennia alba are known to have several bioactive types, so they are potential as biolarvacides. This study aimed to determine the potential of S. alba and A. alba leaf extracts as biolarvacides against Aedes aegypti mosquito larvae. This research was true experimental with a post-test-only group design. The larvicidal toxicity test of the leaf extracts of S. alba and A. alba against Ae. aegypti larvae to obtain the LC50 value was carried out by treating the extract concentrations at 500 ppm, 1,000 ppm, and 1,500 ppm. Synthetic larvicide (abate) was used as a positive control and Aquadest as a negative control. Data analysis was carried out descriptively and statistically (probit analysis). The results showed that the leaf extracts of S. alba and A. alba had potential as biolarvacides. Based on the LC50 value, the extracts of A. alba (LC50: 1,053 ppm) were more potent as biolarvacides than the extracts of S. alba (LC50: 14,112 ppm). Physical damage and behavioral changes in mosquito larvae movement indicated that the toxicity of A. alba leaf extract was acute while that of S. alba leaf extract was chronic.

Using Rhizhopora apiculata Extract for Mosquito Larvae Control

Temephos is the most commonly used synthetic larvicide to control vectors of several diseases. Currently in some areas there has been resistance of larvae to temephos, so natural larvicides are needed as an alternative. Rhizophora apiculata contains flavonoid compounds that are respiratory toxins to some larvae. This research was conducted in March - Juny 2022, to determine the inhibitory of mangrove extract against mosquito larvae in brackish water. Samples were collected from the Bakar Bakau Dumai, Riau Indonesia. The experiment was setted in a single factor experimental design. Mangrove leaves are finely ground and kneaded while mixed with water and deposited for 6 minutes and filtered. This extract solution was mixed with brackish water to obtain a test medium of 500 l with a concentration of 6 (a1), 9 (a2) and 12% (a3), positive control or 1 g of abate powder (a4) and negative control or brackish water (a0). A total of 20 mosquito larvae were put into the media and their mortality was observed at 0, 15, 30, 45 and 60 minutes after introduction. The mortality of larvae were then analyzed using probit analysis to obtain LC50 (Lethal Concentration 50) and LT50 (Lethal Time 50) values. R. apiculata extract is toxic to mosquito larvae, where larval death has been seen since 15 minutes and continues until 60 minutes after introduction. At the 60th minute the mortality rate is as follows; a1 (60 %), a2 (80 %), a3 (100 %), a4 (100 %), and a0 a1 ( %). Based on the results of the above probit values ​​in the LC50 and LT50 tests on R. apiculata leaves, the LC50 value is 9,732 while the LT50 value is estimated at 21,217.

Sublethal effects of oregano essential oil and its major compound carvacrol on biological parameters of Aedes albopictus (Diptera: Culicidae)

Mosquito management programs rely basically on the use of conventional synthetic larvicides. However, frequent applications and misuse of some synthetic insecticides have led to problems related to mosquito resistance development, harmful effects on human health and unacceptable environmental effects on non-target organisms. Recently, a growing number of phytochemicals has been tested as more eco-friendly larvicides against various mosquito species, exerting high efficacy with multiple modes of action. In the laboratory, we investigated for the first time the sublethal effects of oregano oil and its major compound carvacrol, against Aedes albopictus (Asian tiger mosquito), a mosquito of great medical importance. We determined the effects of short term (24h) exposure of 3rd- 4th larvae to LC50 concentrations on survival and development of survived larvae until adulthood, as well as on fecundity, fertility, longevity and wing length of emerged adults. Only half of 24h survived larvae from oregano oil and carvacrol treatment finally reached adulthood. Abnormal shapes of dead larvae and pupae, and failed adult emergence were also observed, indicating a potential growth inhibitory activity of the tested materials. No particular effects from exposure to larvicidal LC50 concentrations were recorded on life cycle parameters of successfully emerged adults. These findings suggest the tested oregano oil and carvacrol as sufficiently effective larvicides against Ae. albopictus at lower than the acutely toxic concentrations, promoting a more eco-friendly and less costly profile for these biopesticides.

Larvicidal Effects of Nanoliposomes Containing Clove and Cinnamon Essential Oils, Eugenol, and Cinnamaldehyde against the Main Malaria Vector, Anopheles stephensi Liston

The use of larvicides, especially in endemic regions, is recommended for malaria control. However, due to the excessive use of synthetic larvicides, resistance in mosquitoes and environmental pollution have been challenges. In the current study, nanoliposome containing clove and cinnamon essential oils and their major ingredients, i.e., eugenol and cinnamaldehyde, were first prepared; particle size and successful loading were investigated using DLS (Dynamic Light Scattering) and ATR-FTIR (Attenuated Total Reflection-Fourier Transform InfraRed) analysis. Larvicidal effects of the nanoliposomes and nonformulated samples were then investigated against Anopheles stephensi. The best-observed efficacy (LC50 5.4 μg/mL) was related to nanoliposomes containing eugenol with a particle size of 109 ± 4 nm. However, LC50 values of the other three nanoformulations were also around 10 μg/mL; all four prepared nanoformulations were thus introduced as natural larvicides for further investigations in the field conditions.

Field larvicidal and oviposition repellent efficacy of three essential oil formulations for the control of filaria vector mosquito Culex quinquefasciatus Say (Diptera: Culicidae): A kill and push concept

The field larvicidal and oviposition repellent efficacies of emulsifiable formulations of botanical oils, (CN-citronella oil, EU-eucalyptus oil, PN-pine oil, PN+EC-combination of pine and eucalyptus oil in 1:1 ratio), against Culex quinquefasciatus mosquitoes. • Larval mosquito control is vital to curb vector population and thereby disease transmission. • Synthetic larvicides cause insecticide resistance and environmental toxicity in mosquitoes. • Three botanical oils were tested against filaria vector Culex quinquefasciatus mosquitoes. • Eucalyptus and pine oils were potent larvicide and oviposition repellent than citronella. • The emulsifiable formulations are effective for multiple weeks under the field conditions. Biological control of larval mosquitoes is in great demand due to the development of resistance against synthetic insecticides, environmental toxicity and the inability to protect habitats from further oviposition. In the present study, three botanical essential oils (BEOs) – citronella, eucalyptus, and pine oils – were formulated for the assessment of larvicidal and oviposition repellent efficacies against Culex quinquefasciatus Say , the filaria vector . The GC–MS profiling of BEOs showed the presence of 16 – 19 compounds covering 87.7–93% of oil composition. The resistance status of Culex quinquefasciatus population was evaluated with temephos (LC 50 = 0.001 ppm, LC 90 = 0.01 ppm) . Larval bioassay of emulsifiable concentrate (EC) formulations prepared from eucalyptus and pine oils showed promising efficacy (LC 50 = 22.7 and 23.2 ppm) and LC 90 (63.8 and 62.4 ppm) compared to citronella oil EC (LC 50 = 43.4 ppm and LC 90 = 199.0 ppm). The field trials of eucalyptus + pine (1:1 ratio) EC showed 100% larval mortality for 3 weeks at 300 ppm compared to 2 weeks of individual oils. Further, the oviposition attraction index (OAI) for ECs of eucalyptus, pine, and their combination showed complete protection of breeding habitats from oviposition at 1st week and −0.9 to −1.0 OAI at 2nd week with slight reduction to −0.5 at 3rd week. Citronella EC provided shortest larvicidal and oviposition repellent efficacy under the field conditions. The promising mosquitocidal activities of EC formulations of eucalyptus and pine or their combination suggest them as potential biocontrol vector control candidates over citronella oil.

CHEMICAL CONSTITUENTS AND LARVICIDAL ACTIVITY OF VOLATILE OIL FROM Solenostemon monostachyus (P Beauv.) Briq. AGAINST Anopheles gambiae

Synthetic larvicides have been used to control malarial vector. However, increasing resistance of mosquito larvae to the synthetic larvicides poses great problem in the vector control. Natural control with plant essential oil may serve as an alternative. This study investigates the chemical constituents and larvicidal activity of volatile oil obtained from Solenostemon monostachyusagainst the larvae of Anopheles gambiae. The volatile oils were extracted using hydro-distillation in a Clevenger type apparatus and analyzed using GC-MS. The larvicidal assay was carried out against Anopheles gambiae larvae at concentration range of 12.5- 400 μg/mL. The analysis of the volatile oil showed that the major constituents of the oil were Caryophyllene oxide (21.6%), β-Caryophyllene (19.6%), β-Pinene (9.8%) and Germacrene D (7.3%). Results showed that larval mortality increases with increasing exposure period to the volatile oils from S. monostachyus. The larvicidal activity demonstrated that the mosquito larvae were susceptible to the volatile oil with LC50 of 23.44 μg/mL. The results suggest that S. monostachyus essential oil has potentials for the control of Anopheles gambiae. Therefore the plant may serve as a potential source of raw material for a new and eco-friendly larvicide.

Efektivitas Kombinasi Ekstrak Lidah Buaya dan Lidah Mertua Terhadap Mortalitas Larva Aedes aegypti

The Dengue Haemoragic Fever (DHF) vector control with synthetic larvicide has an impact on health and environmental problems, so alternative plant-based insecticides are needed. The study aims to determine the larvicidal effect of a combination with Aloe vera extract and Sansivieria trifasciata on the mortality of Aedes aegypti larvae. This study was conducted with experimental design by a post-test only with control groups design consisting of five groups. Two groups are positive control (1% temephos) and negative control (0% concentration). The other three groups served as a combination of Aloe vera extract and S. trifasciata Prain in ratio of 75%:25% (P1), 50%:50% (P2), and 25%:75% (P3). A total of 375 larvae were introduced in this study with three replications and with observation time of 30 minutes, 1 hour, 3 hours, 6 hours, 12 hours, 24 hours until totally died 100%. The mortality of Aedes aegypti larvae were analyzed by Kruskal Wallis and probit analysis to calculate LC50 and LC90. The larvae totally died 100% after 12 hours of exposure. There are significant differences in the mortality of Ae. aegypti larvae after administration of a combination with Aloe vera extract and S. trifasciata Prain. The P1 group (The combination with Aloe vera extract and S. trifasciata Prain with a ratio of 75%:25%) was the most effective in mortality of Ae. aegypti larvae. The LC50 value is 0.517% while the LC90 value is 2.121% within 6 hours. The combination group of Aloe vera extract and mother-in-law's tongue with a ratio of 75%:25% was the most effective in causing mortality of Ae. aegypti within 6 hours.