Disruption of Darna pallivitta (Lepidoptera: Limacodidae) by Conventional and Mobile Pheromone Deployment

Identification of the Darna pallivitta (Moore) pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOn-Bu) has made it possible to investigate communication disruption to control this lepidopteran pest. Conventional communication disruption trials showed marked decreases in the mean number of male moths captured in E7,9-10:COOnBu-treated fields compared with control fields. For traps baited with E7,9-10:COOnBu, percent disruptions were 94.4% and 92.1% for septa (1 g pheromone/ha, 1-wk trial duration) and spirals (6 g pheromone/ha, 8-wk trial duration) respectively. For traps baited with virgin female moths, percent disruption was 73.3% using septa disruptors (1 g pheromone/ha, 1-wk trial duration). Mobile communication disruption using Bactrocera cucurbitae (Coquillett) as carriers for E7,9-10:COOn-Bu was evaluated in the following three areas: fly survivorship, attraction of male moths to treated flies, and moth disruption in a small-scale field trial. Topical application of E7,9-10:COOnBu showed no significant decrease in survivorship at 50 and 80 µg/fly. However, decreased survivorship was observed at 100 µg/fly and linear regression showed E7,9-10:COOnBu dose was significantly correlated with B. cucurbitae survivorship. Traps containing honey–pheromone-fed flies attracted and caught D. pallivitta over a 1-wk period, demonstrating the attractiveness of the carrier. Releasing E7,9-10:COOnBu-fed B. cucurbitae (∼2 g pheromone/ha, 1-wk trial duration) resulted in significantly reduced trap catches in treatment fields compared with control fields on the first 2 d of the field trial. Percent disruptions were 84.7% (day 1) and 56.0% (day 2). These results suggest that both conventional communication disruption and mobile communication disruption have potential to control D. pallivitta.     

Geographic Variation of Diapause and Sensitive Stages of Photoperiodic Response in Laodelphax striatellus Fallén (Hemiptera: Delphacidae)

Large numbers of the small brown planthopper Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) occur in temperate regions, causing severe losses in rice, wheat, and other economically important crops. The planthoppers enter diapause in the third- or fourth-instar nymph stage, induced by short photoperiods and low temperatures. To investigate the geographic variation in L. striatellus diapause, we compared the incidence of nymphal diapause under various constant temperature (20 and 27°C) and a photoperiod of 4:20, 8:16, 10:14, 12:12, 14:10, and 16:8 (L:D) h regimes among three populations collected from Hanoi (21.02° N, 105.85° E, northern Vietnam), Jiangyan (32.51° N, 120.15° E, eastern China), and Changchun (43.89° N, 125.32° E, north-eastern China). Our results indicated that there were significant geographic variations in the diapause of L. striatellus. When the original latitude of the populations increased, higher diapause incidence and longer critical photoperiod (CP) were exhibited. The CPs of the Jiangyan and Changchun populations were ∼12 hr 30 min and 13 hr at 20°C, and 11 hr and 11 hr 20 min at 27°C, respectively. The second- and third-instar nymphs were at the stage most sensitive to the photoperiod. However, when the fourth- and fifth-instar nymphs were transferred to a long photoperiod, the diapause-inducing effect of the short photoperiod on young instars was almost reversed. The considerable geographic variations in the nymphal diapause of L. striatellus reflect their adaptation in response to a variable environment and provide insights to develop effective pest management strategies.     

Biological Activity of trans-2-Hexenal Against Bradysia odoriphaga (Diptera: Sciaridae) at Different Developmental Stages

trans-2-Hexenal, one of the C6 green leaf volatiles, is potentially useful for the control of Bradysia odoriphaga Yang et Zhang. In this study, the biological activity of trans-2-hexenal on B. odoriphaga was assessed in the laboratory. trans-2-Hexenal was observed to kill B. odoriphaga in different developmental stages at a relatively low concentration under fumigation. The respiration rate in the male treatment group decreased from 131.44 to 4.07 nmol/g·min with a prolonged fumigation time, while the respiration rate in females decreased from 128.82 to 24.20 nmol/g·min. Male adults exhibited a more sensitive electroantennogram response at 0.05–500 μl/ml at the dose of 10.0 μl than female adults. Moreover, trans-2-hexenal had a repellent effect on adults based on the results with a Y-tube olfactometer at 10.0 μl, as shown by the deterrent rate of male and female adults with 96.67% and 98.33%, respectively. The results showed that trans-2-hexenal had good biological activity in different developmental stages of B. odoriphaga, which could reduce the need for, and risks associated with, the use of traditional insecticides and enable nonharmful management.     

Demographic Parameters of Nezara viridula (Heteroptera: Pentatomidae) Reared on Two Diets Developed for Lygus spp.

Two artificial diets developed for rearing Lygus spp., a fresh yolk chicken egg based-diet (FYD) and a dry yolk chicken egg based-diet (DYD), were evaluated as an alternative food source for rearing the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae). Survival to adult was 97.3 and 74.67%, respectively, on the fresh and dry yolk diets. Insects fed FYD had 100% survival of nymphs from first through fourth instars. Adult development was significantly shorter on FYD (30.37 ± SE 0.30 d) as compared with DYD (32.77 ± SE 0.16 d). Increased male and female longevity, higher fecundity, and larger egg mass sizes were also observed with N. viridula-fed FYD. However, fertility and hatchability was higher on DYD. A complete cohort life table was constructed to describe the development of N. viridula on both diets.     

Investigation into the Effect of Altitude on the Differential Hemocyte Count of Circulating Plasmatocytes and Granulocytes of Larval Stage of Antheraea assama (Lepidoptera: Saturniidae)

Differential hemocyte count of circulating plasmatocytes (PL) and granulocytes (GR) of fifth-instar larvae of Muga Silkworm Antheraea assama Westwood (Lepidoptera: Saturniidae) reared at four different sericulture farms situated at different altitudes, viz, Khanapara State Sericulture Farm, Assam, altitude 55.5 m above sea level (ASL); Nongpoh (Central Silk Board farm), Meghalaya, altitude 464 m ASL; Tura (Central Silk Board farm), West Garo Hills, Meghalaya, 657 m ASL; and Kalimpong (Central Silk Board farm), West Bengal, altitude 1,247 m ASL, were calculated and compared to investigate the effect of altitude on the number of PL and GR per mm³ of larval hemolymph. The investigation showed that the mean circulating PL and GR were highest at Khanapara (55.5 m ASL) located at the lowest altitude, whereas their numbers gradually decreased with increase in altitude at Nongpoh (464 m ASL), Tura (657 m ASL), and Kalimpong (1,247 m ASL). This may be attributed to the average environmental temperatures observed at different altitudes, which may affect the overall hemocyte load of larval stages reared at those altitudes.     

The Effect of Chemical Composition and Bioactivity of Several Essential Oils on Tenebrio molitor (Coleoptera: Tenebrionidae)

The major chemical components of four essential oils (EOs) extracted from dry leaves of Citrus limonum, Cymbopogon citratus, Litsea cubeba, and Muristica fragrans were analyzed with gas chromatograph-mass spectrometer and their fumigant, contact, and repellent activities against 10th instar and adults of Tenebrio molitor were also assayed. The results indicated that the major constituents of C. limonum and Cy. citrates were D-limonene (38.22%) and 3,7-dimethyl-6-octenal (26.21%), while which of L. cubeba and M. fragrans were (E)-3, 7-dimethyl-2, 6-octadienal (49.78%) and (E)-cinnamaldehyde (79.31%), respectively. Contact activities of L. cubeba and C. limonum with LC₅₀ values of 21.2 and 13.9 µg/cm² at 48 h and repellence activities (>89.0% repellence indexes) (P < 0.05) at 12 h on 10th instar were better than those of the other two EOs. Nevertheless, the fumigation activities of L. cubeba on 10th instar and adults (LC₅₀ = 2.7, 3.7 μl/liter) were stronger than those of C. limonum (LC₅₀ = 10.9, 12.0 μl/liter) at 96 h and significant (not overlapping confidence intervals). The EOs of L. cubeba and C. limonum have clearly elongated the growth and development of larvae, egg, and slightly shorten pupae and adults of T. molitor compared with the control. The mainly active ingredients of L. cubeba and C. limonum, including D-limonene and β-pinene, were demonstrated to coinhibit the actives of AChE and enhance the toxicities on 10th instar of T. molitor. These results indicate that the EOs of L. cubeba and C. limonum could have great potential as botanical insecticides against T. molitor.     

Development of Temporal Modeling for Forecasting and Prediction of the Incidence of Lychee,Tessaratoma papillosa (Hemiptera: Tessaratomidae), Using Time-Series (ARIMA) Analysis

The most destructive enemy of the lychee, Litchi chinensis Sonn. (Sapindales: Sapindaceae), in India is a stink bug, Tessaratoma papillosa (Drury) (Hemiptera: Tessaratomidae). The population of T. papillosa on lychee trees varied from 1.43 ± 0.501 to 9.85 ± 3.924 insects per branch in this study. An increase in the temperature and a decrease in the relative humidity during summer months (April to July) favor the population buildup of T. papillosa. A forecasting model to predict T. papillosa incidences in lychee orchards was developed using the autoregressive integrated moving average (ARIMA) model of time-series analysis. The best-fit model for the T. papillosa incidence was ARIMA (1,1), where the P-value was significant at 0.01. The highest T. papillosa incidences were predicted for April in 2010, January in 2011, May in 2012, and February in 2013. A model based on time series offers longer-term forecasting. The forecasting model, ARIMA (1,1), developed in this study will predict T. papillosa incidences in advance, thus providing functional guidelines for effective planning of timely prevention and control measures.     

Influence of Constant Temperature on Reproductive Parameters of Holotrichia oblita (Coleoptera: Scarabaeidae)

Holotrichia oblita Faldermann (Coleoptera: Scarabaeidae) is a major pest both in field crops and forests because the larvae could eat the roots of most crops in the field, and the adults damage the leaves of trees and field crops. In this study, we focused on the effects of temperature on H. oblita reproductive parameters. The results indicated H. oblita female adults at 25°C could lay more eggs (84.0 eggs per female) and have the shortest preoviposition period (19.1 d), the greatest oviposition rate (2.8 eggs per female per 3 d), and largest percentage of life span spent in oviposition (59.5%). The longevity and the time to 50% egg laying decreased with increasing temperature, and female longevity was always longer than male longevity. The preoviposition and postoviposition period decreased with increasing temperature from 15 to 25°C and then increased when the temperature increased from 25 to 30°C. These results show that 25°C is the optimal temperature for reproduction of H. oblita.     

Laboratory Evaluation of Acute Toxicity of the Essential Oil of Allium tuberosum Leaves and Its Selected Major Constituents Against Apolygus lucorum (Hemiptera: Miridae)

The aim of this research was to evaluate acute toxicity of the essential oil of leaves of Chinese chives, Allium tuberosum Rottler ex Spreng (Asparagales: Alliaceae) and its major constituents against Apolygus lucorum Meyer-Dür (Hemiptera: Miridae). The essential oil of A. tuberosum leaves was obtained by hydrodistillation and analyzed by gas chromatography and gas chromatography-mass spectrometry. The major constituents of the oil were sulfur-containing compounds, including allyl methyl trisulfide (36.24%), diallyl disulfide (27.26%), diallyl trisulfide (18.68%), and dimethyl trisulfide (9.23%). The essential oil of A. tuberosum leaves exhibited acute toxicity against Ap. lucorum with an LD₅₀ value of 20.03 μg per adult. Among the main compounds, diallyl trisulfide (LD₅₀ = 10.13 μg per adult) showed stronger acute toxicity than allyl methyl trisulfide (LD₅₀ = 21.10 μg per adult) and dimethyl trisulfide (LD₅₀ = 21.65 μg per adult). The LD₅₀ value of diallyl disulfide against Ap. lucorum was 28.10 μg per adult. The results indicated that the essential oil of A. tuberosum and its major constituents may have a potential to be developed as botanical insecticides against Ap. lucorum.     

Chemical Composition,Antifeedant, Repellent,and Toxicity Activities of the Rhizomes of Galangal,Alpinia galanga Against Asian Subterranean Termites,Coptotermes gestroi and Coptotermes curvignathus (Isoptera: Rhinotermitidae)

Dual choice bioassays were used to evaluate the antifeedant property of essential oil and methanolic extract of Alpinia galanga (L.) (locally known as lengkuas) against two species of termites, Coptotermes gestroi (Wasmann) and Coptotermes curvignathus (Holmgren) (Isoptera: Rhinotermitidae). A 4-cm-diameter paper disc treated with A. galanga essential oil and another treated with either methanol or hexane as control were placed in a petri dish with 10 termites. Mean consumption of paper discs (miligram) treated with 2,000 ppm of essential oil by C. gestroi was 3.30 ± 0.24 mg and by C. curvignathus was 3.32 ± 0.24 mg. A. galanga essential oil showed significant difference in antifeedant effect, 2,000 ppm of A. galanga essential oil was considered to be the optimum concentration that gave maximum antifeedant effect. The essential oil composition was determined using gas chromatography-mass spectrometry. The major component of the essential oil was 1,8-cineol (61.9%). Antifeedant bioassay using 500 ppm of 1,8-cineol showed significant reduction in paper consumption by both termite species. Thus, the bioactive agent in A. galangal essential oil causing antifeeding activity was identified as 1,8-cineol. Repellent activity shows that 250 ppm of 1,8-cineol caused 50.00 ± 4.47% repellency for C. gestroi, whereas for C. curvignathus 750 ppm of 1,8-cineol was needed to cause similar repellent activity (56.67 ± 3.33%). C. curvignathus is more susceptible compare to C. gestroi in Contact Toxicity study, the lethal dose (LD₅₀) of C. curvignathus was 945 mg/kg, whereas LD₅₀ value for C. gestroi was 1,102 mg/kg. Hence 1,8-cineol may be developed as an alternative control against termite in sustainable agriculture practices.     

Parasitism,Emergence, and Development of Spalangia endius (Hymenoptera: Pteromalidae) in Pupae of Different Ages of Bactrocera cucurbitae (Diptera: Tephritidae)

The wasp Spalangia endius Walker (Hymenoptera: Pteromalidae) is a major parasitoid of the pupae of fruit flies, which are a common agricultural pest. An understanding of this intricate host–parasitoid interaction could provide basic information necessary for the sustainable integrated biological control of fruit flies. In this study, we investigated the effect of S. endius on different-aged pupae of the melon fly Bactrocera cucurbitae Coquillett by using choice and nonchoice tests under laboratory conditions. We showed that S. endius females oviposited, and their progeny successfully developed, in different-aged pupae of B. cucurbitae regardless of the method of exposure. There was an oviposition preference for 3–5-d-old pupa. The highest mean percentage parasitism occurred on 4- and 5-d-old hosts, followed by 2- and 3-d-old hosts. The average development time for both males and females was significantly longer in 6–7-d-old hosts than in the younger host stages. Adult females that developed from younger host pupae (2–5-d old) were significantly heavier than those from older host pupae (6–7-d old), and they also lived longer. The sex ratio (proportion of females) of the parasite progeny decreased with an increase in host age. Host mortality also decreased gradually as the pupal age increased. The differences in development time, body weight, and longevity between females and males were significant. These results suggest that S. endius is a good candidate for the biological control of B. cucurbitae.     

Insecticidal Activity and Insect Repellency of Four Species of Sea Lily (Comatulida: Comatulidae) From Taiwan

The methanol and ethyl acetate (EA) extracts of four species of sea lily (Himerometra magnipinna, Comaster multifidus, Comanthina sp., and Comatella maculata) were evaluated for their insecticidal activity against Yellow-fever mosquito larvae (Aedes aegypti) and their repellency against adult Asian Tiger mosquitoes (Aedes albopictus). The 24-hr minimum inhibition concentration (MIC) data revealed that the extracts from H. magnipinna and the C. maculata were the most active, killing mosquito larvae at 12.5 ppm. The toxicity of the extracts from these four sea lilies in descending order was H. magnipinna (12.5 ppm), C. maculata (12.5 ppm), C. multifidus (100 ppm), and Comanthina sp. (200 ppm). Furthermore, no significant difference in toxicity was found using either EA or methanol as the extraction solvent. The MIC at 12.5 ppm is promising as an insecticide lead. The repellency study results show that EA is a better solvent for one species (H. magnipinna), but the methanol is a better solvent overall. The repellency of these sea lily extracts in descending order was Comanthina sp. MeOH (ED₅₀ at 0.32%), followed by H. magnipinna EA (ED₅₀ at 0.38%), C. multifidus MeOH (ED₅₀ at 0.57%), C. maculata MeOH (ED₅₀ at 0.76%), C. multifidus EA (ED₅₀ at 1.25%), and H. magnipinna MeOH (ED₅₀ at 1.67%). A compound with ED₅₀ <0.5% is considered to be a promising repellant. Among the studied sea lilies, both Comanthina sp. and H. magnipinna have potential to be further developed as mosquito control agents due to their favorable toxicity and repellency.     

Efficacy of Plectranthus glandulosus (Lamiaceae) and Callistemon rigidus (Myrtaceae) Leaf Extract Fractions to Callosobruchus maculatus (Coleoptera: Bruchidae)

As part of on-going efforts to use eco-friendly alternatives to chemical pesticides, methanol crude extracts of Plectranthus glandulosus and Callistemon rigidus leaves were sequentially fractionated in hexane, chloroform, ethyl acetate, and methanol to establish the most active fraction(s) against Callosobruchus maculatus in cowpea. Cowpea seeds (25 g) were treated with 0.5, 1, 2, and 4 g/kg of extract to evaluate the contact toxicity and F₁ progeny production of the beetles in the laboratory. Mortality was recorded 1, 3, and 7 d postexposure. P. glandulosus hexane fraction was more toxic than the other fractions recording 100% mortality at 4 g/kg, within 7 d with LC₅₀ of 0.39 g/kg. Hexane fraction of C. rigidus showed superior toxicity, causing 100% mortality at 4 g/kg within only 1 d of exposure with LC₅₀ of 1.02 g/kg. All the fractions greatly reduced progeny emergence, with C. rigidus hexane fraction being the best progeny inhibitor. Fractions of P. glandulosus and C. rigidus leaves had sufficient efficacy to be a component of storage pest management package for C. maculatus.     

Survival of Coelaenomenodera lameensis (Coleoptera: Chrysomelidae) in Relation to the Physical Characteristics of Different Oil Palm (Elaeis sp.) Breeding Populations

The edibility of different Elaeis sp. breeding populations present in Benin was tested for the leaf miner Coelaenomenodera lameensis Berti (Coleoptera: Chrysomelidae), a major oil palm pest in Africa. Experiments carried out in sleeves revealed the oviposition capacities of females and the mortality rates for the different developmental stages by comparing the populations found on two breeding populations of Elaeis oleifera (HBK) Cortes, four of Elaeis guineensis Jacquin and four (E. guineensis × E. oleifera) × E. guineensis backcrosses. Females laid their eggs similarly on all breeding populations, with a preference for the E. guineensis La Mé origin. The average hatching rate reached 80% for the La Mé origin as opposed to 28% for the Deli origin. The mortality rates for the larval instars were greater on E. oleifera, on certain backcrosses and on the Deli origin of E. guineensis. Development at the second- and third- larval instars was the most affected, with a mortality rate of three to five times greater than that seen on La Mé. Epidermis and cuticle measurements indicated which breeding populations were suitable or unsuitable for the development of C. lameensis. E. guineensis, with its thin epidermis (12 µm) and cuticle (2 µm), proved to be highly susceptible to C. lameensis attacks. On the other hand, E. oleifera, which is very resistant, exhibited a thicker epidermis (17 µm) and cuticle (4 µm). The breeding populations were thus classified according to the positive or negative influence they exerted on the insect’s egg laying and feeding.RÉSUMÉ. La comestibilité de différents matériels végétaux d’Elaeis sp. présents au Bénin est testée pour Coelaenomenodera lameensis Berti (Coleoptera: Chrysomelidae), important ravageur du palmier à huile en Afrique. Des expérimentations en manchons ont permis de déterminer les capacités d’oviposition des femelles et les taux de mortalité des différents stades de développement (œufs, larves, nymphes et adultes) en comparant les populations observées sur deux origines d’Elaeis oleifera (HBK) Cortes, quatre origines d’Elaeis guineensis Jacquin et quatre Backcross (E. guineensis × E. oleifera) × E. guineensis. Les femelles pondent indifféremment sur tous les types de matériel végétal avec une préférence pour l’origine La Mé d’E. guineensis. Le taux moyen d’éclosion atteint 80% pour l’origine La Mé contre 28% pour l’origine Deli. Le taux de mortalité des stades larvaires est plus important sur E. oleifera, sur certains Backcross et sur l’origine Deli d’E. guineensis. Le développement des deuxième et troisième stades larvaires sont les plus affectés avec un taux de mortalité 3 à 5 fois supérieur à celui observé sur La Mé. Des mesures d’épiderme et de cuticule mettent en évidence l’existence de matériel végétal favorable ou défavorable au développement de C. lameensis. E. guineensis dont l’épiderme (12 µm) et la cuticule (2 µm) sont peu épais se révèle être très sensible aux attaques de C. lameensis. Au contraire, E. oleifera présente un épiderme (17 µm) et une cuticule (4 µm) plus épais et est très résistants. Le matériel végétal est ainsi classé suivant l’influence positive ou négative qu’ils exercent sur la ponte et l’alimentation des insectes.     

Contact Toxicity and Repellency of the Main Components From the Essential Oil of Clausena anisum-olens Against Two Stored Product Insects

The essential oil of Clausena anisum-olens (Blanco) Merr. showed strong contact toxicity and repellency against Lasioderma serricorne and Liposcelis bostrychophila adults. The components of the essential oil obtained by hydrodistillation were determined by gas chromatography-mass spectrometry. It was found that the main components were myristicin (36.87%), terpinolene (13.26%), p-cymene-8-ol (12.38%), and 3-carene (3.88%). Myristicin and p-cymene-8-ol were separated by silica gel column chromatography, and their molecular structures were confirmed by means of physicochemical and spectrometric analysis. Myristicin and p-cymene-8-ol showed strong contact toxicity against L. serricorne (LD₅₀ = 18.96 and 39.68 μg per adult) and Li. bostrychophila (LD₅₀ = 20.41 and 35.66 μg per adult). The essential oil acting against the two grain storage insects showed LD₅₀ values of 12.44 and 74.46 μg per adult, respectively. Myristicin and p-cymene-8-ol have strong repellent toxicity to Li. bostrychophila.     

Identification of the Population Structure of Myzus persicae (Hemiptera: Aphididae) on Peach Trees in China Using Microsatellites

In this study, we characterized the genetic structure of Myzus persicae (Sulzer) (Hemiptera: Aphididae) populations in China using microsatellites. We expected that these data will reveal the genetic relationships among various populations of M. persicae and will be of value in the development of better methods for pest control. Four hundred sixty individuals from 23 areas over 13 provinces were collected in the early spring of 2010, all from their primary host, Prunus persicae. The markers analyzed were highly polymorphic, as demonstrated by the expected heterozygosity value (H_e = 0.861) and the Polymorphism Information Content (PIC = 0.847), which indicated that M. persicae maintains a high level of genetic diversity. Analysis of molecular variance revealed an intermediate level of population differentiation among M. persicae populations (F_ST = 0.1215). Geographic isolation existed among these populations, and, consequently, the genetic structure of the populations was split into a southern group and a northern group divided by the Yangtse River.     

Creams Formulated with Ocimum gratissimum L. and Lantana camara L. Crude Extracts and Fractions as Mosquito Repellents Against Aedes aegypti L. (Diptera: Culicidae)

Mosquitoes are the most deadly vectors of parasites that cause diseases such as malaria, yellow fever, and filariasis. In view of the recent increased interest in developing plant origin insecticides as an alternative to chemical insecticides, the objective of this study was to determine the repellent activity of creams formulated with methanol crude extract (MCE), hexane fraction (HF), and ethyl acetate fractions (EAFs) of Ocimum gratissimum and Lantana camara leaves in single and combined actions against female Aedes aegypti. Evaluation was carried out in the net cages (30 by 30 by 30 cm) containing 60 blood-starved female mosquitoes each and were assayed in the laboratory condition following World Health Organization 2009 protocol. All formulations (single and mixture) were applied at 2, 4, 6, and 8 mg/cm² in the exposed area of human hands. Only acetone + white soft paraffin served as negative control and odomos (12% DEET) as positive control. All the formulations presented good protection against mosquito bites without any allergic reaction by the human volunteers. The repellent activity was dependent on the strength of the extracts and fractions. Among the tested formulations, the maximum protection time was observed in MCE (120 min) and EAF (150 min) of O. gratissimum; MCE:MCE (150 min) and HF:HF (120 min) mixtures of both plants. In addition, MCE:MCE and HF:HF mixtures from both plants showed possible synergistic effect. From the results, the combination of O. gratissimum and L. camara to formulate natural mosquito repellent using small amount of extracts can be encouraging to be an alternative to conventional DEET.