Contact and fumigant toxicities of calamusenone isolated from Acorus gramineus rhizome against adults of Sitophilus zeamais and Rhizopertha dominica

Abstract Calamusenone [3,8‐dimethyl‐5‐(1‐methylethylidene)‐1,2,3,4,5,6,7,8‐octahydroazulene‐6‐one, C₁₅H₂₂O] from Acorus gramineus Soland rhizome was tested in the laboratory for its insecticidal activities against adults of Sitophilus zeamais Motsch. and Rhizopertha dominica (Fab.), using dry film contact and fumigation methods. Responses varied with insect species, dosage and exposure time. In the dry film contact experiment, the highest insecticidal effects of calamusenone against S. zeamais and R. dominica adults were produced at 170.32 μg/cm² after treatment for 72 h, with 96.2% and 98.7% mortalities, respectively. The median lethal concentration (LC₅₀) (72 h) values of calamusenone against S. zeamais and R. dominica adults were 67.00 μg/cm² and 77.30 μg/cm², respectively. As a potential fumigant, calamusenone showed moderate insecticidal effect on the adults of S. zeamais and R. dominica in fumigation experiment, with their LC₅₀ (120 h) values of 125.71 μL/L and 93.64 μL/L respectively. Calamusenone isolated from A. gramineus rhizome showed promise as a novel pesticide candidate for stored‐product pest control.     

A Novel Tropoloisoquinoline Alkaloid,Neotatarine, from Acorus calamus L.

A novel tropoloisoquinoline alkaloid, neotatarine ( 1 ), was isolated from the 95% ethanol extract of the rhizome parts of Acorus calamus L. The chemical structure was unambiguously elucidated by spectroscopic and single‐crystal X‐ray diffraction analysis. Neotatarine ( 1 ) exhibited significantly inhibitory activity against Aβ_{25 – 35} induced PC12 cell death with 2, 4 and 8 μm comparing with the assay control (P < 0.01).     

High‐throughput screening method for evaluating spatial repellency and vapour toxicity to mosquitoes

Spatial repellents are an essential tool for personal protection against mosquitoes that bite and transmit disease pathogens to humans. Current repellent screening methods, such as olfactometers and alternative choice tests, are complex systems that require a relatively large quantity of compound (mg). The present study validates a high‐throughput spatial repellent screening method using a glass tube that has the ends covered with netting, in addition to treated filters and plastic end caps. The apparatus occupies relatively little space, is easy to decontaminate, and requires small amounts of compound (μg). In a horizontal tube orientation, DEET (N,N‐diethyl‐meta‐toluamide), citronella oil and IR3535 had 1 h half repellent concentration (EC₅₀) values of 32, 32 and 298 μg/cm², respectively, against the Orlando strain of Aedes aegypti (L.) (Diptera: Culicidae). Vertical tube orientation increased EC₅₀ values by approximately two‐fold, except IR3535, which remained essentially unchanged. Transfluthrin showed concentration‐dependent spatial repellency (1 h EC₅₀ = 0.5 μg/cm²) without any knockdown, although only in vertical tubes. Transfluthrin showed 50% knockdown in 1 h at 0.5 μg/cm² and 50% mortality at 0.15 μg/cm² in horizontal tubes. In conclusion, this high‐throughput screening method is useful for assessing vapour toxicity and the spatial repellency of candidate molecules prior to semi‐field and field studies.     

First report of the repellency of 2-tridecanone against ticks

2‐Tridecanone and 2‐undecanone are both found naturally in the trichomes of wild tomato plants and are important in plant resistance to herbivory. 2‐Undecanone is the U.S. Environmental Protection Agency (EPA)‐registered active ingredient in the commercially available arthropod repellent, BioUD^®. The goal of this study was to examine the tick repellency of 2‐tridecanone. Two‐choice bioassays were conducted using 8% 2‐tridecanone vs. the repellent carrier (absolute ethanol) and compared with two‐choice studies using 8% 2‐undecanone vs. absolute ethanol. Unfed, host‐seeking adult (mixed sex) Amblyomma americanum (L.) (Acari: Ixodidae) and Dermacentor variabilis Say (Acari: Ixodidae) were used to evaluate repellency and time to repellent failure at room temperature. The present study shows in filter paper assays (0.63 mg test compound/cm²) that 2‐tridecanone was 87% repellent to A. americanum at 12 h after application, but had no statistically significant repellency at 15 h and 24 h, and was 72% repellent to D. variabilis at 15 h, but had no statistically significant repellency at 24 h. By contrast, 2‐undecanone was 74% and 75% repellent to A. americanum and D. variabilis, respectively, at 2 h after application, but no statistically significant repellency was noted at 2.5 h and 3 h. In two‐choice assays on cheesecloth, 2‐tridecanone at 0.25 mg/cm² was 85% repellent to A. americanum 6 h after application, demonstrating its potential use as an arthropod repellent that can be used on clothing without the need for formulation. No statistically significant repellency was found at 9 h or 12 h. The potential use of 2‐tridecanone as a tick repellent is discussed.     

Bioactivity of fenchone and Plectranthus glandulosus oil against Prostephanus truncatus and two strains of Sitophilus zeamais

The toxic, repellent and reproduction inhibitory effects of Plectranthus glandulosus essential oil and one of its major compounds, fenchone, were evaluated against adult Prostephanus truncatus (Horn) and for two strains of Sitophilus zeamais Motschulsky from Cameroon and Germany. Maize grains were coated with the oil at 0, 10, 20, 40 and 80 μl/40 g grain and fenchone at 0, 20, 40, 80 and 120 μl/40 g grain. Mortality was assessed over a 7‐day period, followed by the determination of F₁ progeny production. The repellence of the two products was evaluated at five rates (0.5, 1, 3, 5, 10 μl/half disc) in a choice bioassay on filter paper. The oil and fenchone caused significant dose‐dependent mortality to the three insects, with the oil achieving 100% and 90% mortality for the two S. zeamais strains and P. truncatus, respectively, within 1 day of exposure at the dosage of 80 μl/40 g grain. The insects were less susceptible to fenchone compared with the crude oil. The German strain of S. zeamais was susceptible to the oil than the Cameroonian strain. At the dosage of 20 μl/40 g grain, S. zeamais F₁ progeny emergency was completely inhibited by the oil, while 80 μl/40 g grain treatment with fenchone prevented also insect emergence. Plectranthus glandulosus oil generally evoked a maximum per cent repellency of 100% for the three insects, but fenchone caused 55–60% to S. zeamais and 80% to P. truncatus. These results suggest that fenchone, though a major constituent of P. glandulosus oil, may only be a minor component of its bioactivity.     

Pesticidal and pest repellency activities of rhizomes of Drynaria quercifolia (J. Smith) against Tribolium castaneum (Herbst)

Background

Tribolium castaneum (Herbst) is a harmful pest of stored grain and flour-based products in tropical and subtropical region. In the present study, rhizome of Drynaria quercifolia (J. Smith) was evaluated for pesticidal and pest repellency activities against T. castaneum, using surface film method and filter paper disc method, respectively. In addition, activity of the isolated compound 3,4-dihydroxybenzoic acid was evaluated against the pest.

Results

Chloroform soluble fraction of ethanol extract of rhizome of D. quercifolia showed significant pesticidal activity at doses 0.88 to 1.77 mg/cm² and significant pest repellency activity at doses 0.94 to 0.23 mg/cm². No pesticidal and pest repellency activity was found for petroleum ether, ethyl acetate and methanol soluble fractions of ethanol extract as well as for 3,4-dihydroxybenzoic acid.

Conclusion

Considering our findings it can be concluded that chloroform soluble fraction of rhizome of D. quercifolia is useful in controlling T. castaneum of stored grain and flour-based products.

Electronic supplementary material

The online version of this article (doi:10.1186/0717-6287-47-51) contains supplementary material, which is available to authorized users.     

Cytotoxic effects of β‐asarone on Sf9 insect cells

β‐Asarone is the predominant component of the essential oil of rhizomes of Acorus calamus Linn ( Sweet flag). Although rhizome extracts from this plant have long been used for insect pest control, their cytotoxic effects on insect cells are not well understood. In this study, we evaluated the potency of β‐asarone as a natural insecticide by using a Spodoptera frugiperda cell line (Sf9). To assess the cytotoxic effects of β‐asarone on Sf9 cells, we observed morphologic changes in treated cells and performed a cell proliferation assay and a DNA fragmentation assay. After 24 and 48 h of treatment with β‐asarone, the proliferation of the Sf9 cells was inhibited in a dose‐dependent manner, with IC₅₀ values of 0.558 mg/ml at 24 h and 0.253 mg/ml at 48 h. Morphologic changes in β‐asarone‐treated cells were typical of apoptosis and included loss of adhesion, cell shrinkage, and small apoptotic bodies. The DNA laddering present in β‐asarone‐treated SF9 cells and annexin V assay confirmed that this compound can induce apoptosis in insect cells. Together, these findings suggest that apoptosis induction may be one mechanism through which β‐asarone inhibits the proliferation of insect cells and thus exerts insecticidal effects.     

Toxic and repellent properties of Xylopia aethiopica (Dunal) A. Richard on Tribolium castaneum Herbst infesting stored millets,Pennisetum glaucum (L.) R. Br.

The toxicity and repellency of Xylopia aethiopica seed extract was investigated in the laboratory against Tribolium castaneum Herbst. Concentration and days after treatment (DAT) caused a significant increase in T. castaneum adult mortality with an interaction effect of both on mortality when filter paper was impregnated with X. aethiopica extract. At 0.2 ml/60 cm² extract, significant mortality was observed at three–seven DAT when compared with one DAT. At 0.4 ml/60cm², 100% mortality was recorded at the lowest exposure period of one DAT. When 0.2 ml extract was applied to 5 g millet seeds, mortality at five–seven DAT was significantly higher than mortality observed in the control. Although repellency was dose-dependent, the percentage of T. castaneum that were repelled from treated filter paper was not significant. At 0.4 ml/60 cm², Class II repellency (26.7%) was observed. The results suggest that X. aethiopica can only effectively control T. castaneum populations that have infested millet but do not prevent cross-infestation via repellency.     

Insecticidal and Repellant Activities of Polyacetylenes and Lactones Derived from Atractylodes lancea Rhizomes

During a screening program for new agrochemicals from Chinese medicinal herbs and local wild plants, the petroleum ether (PE) extract of Atractylodes lancea (Thunb. ) rhizomes was found to possess repellent and contact activities against Tribolium castaneum adults. Bioactivity‐directed chromatographic separation of PE extract on repeated silica‐gel columns led to the isolation of two polyacetylenes, atractylodin and atractylodinol ( 1 and 2 , resp.), and two lactones, atractylenolides II and III ( 3 and 4 , resp.). The structures of the compounds were elucidated based on NMR spectra. The four isolated compounds were evaluated for their insecticidal and repellent activities against T. castaneum. Atractylodin exhibited strong contact activity against T. castaneum adults with a LD₅₀ value of 1.83 μg/adult. Atractylodin and atractylenolide II also possessed strong repellenct activities against T. castaneum adults. After 4‐h exposure, >90% repellency was achieved with atractylodin at a low concentration of 0.63 μg/cm². The results indicated that atractylodin ( 1 ) and atractylenolide II ( 3 ) have a good potential as a source for natural repellents, and 1 has the potential to be developed as natural insecticide.     

Contact Toxicity and Repellency of the Essential Oil of Dictamnus dasycarpus Roots from China against Two Stored‐Product Insects

During our screening program for new agrochemicals from traditional medicinal herbs, Dictamnus dasycarpus was found to possess contact toxicity and repellent activity against the cigarette beetle Lasioderma serricorne and the booklouse Liposcelis bostrychophila. The essential oil obtained by hydrodistillation of D. dasycarpus roots was characterized by GC‐FID and GC/MS analyses, and the main components identified were syn‐7‐hydroxy‐7‐anisylnorbornene ( 1 , 49.9%), 1,3,4,5,6,7‐hexahydro‐2H‐inden‐2‐one ( 2 , 11.6%), 5,6‐diethenyl‐1‐methylcyclohexene ( 3 , 7.4%), and 3,9‐dimethyltricyclo[4.2.1.1^2,5]dec‐3‐en‐9‐ol ( 4 , 6.35%). The D. dasycarpus root oil exhibited strong contact toxicity against L. serricorne adults and L. bostrychophila, with LD₅₀ values of 12.4 μg/adult and 27.2 μg/cm², respectively. Moreover, the essential oil also showed strong repellency against both stored‐product insects tested.     

Chemical Constituents and Activities of the Essential Oil from Myristica fragrans against Cigarette Beetle Lasioderma serricorne

Essential oil extracted from nutmeg seeds (Myristica fragrans Houtt .) by hydrodistillation was subjected to GC/MS and GC analysis. A total of 27 constituents were identified, of which eugenol (19.9%), methylisoeugenol (16.8%), methyleugenol (16.7%), sabinene (11.8%), and terpinen‐4‐ol (8.5%) were the major components. The essential oil was tested against Lasioderma serricorne for insecticidal and repellent activity, the LD₅₀ value at the end of 24 h exposure period was 19.3 μg/adult. Six active compounds were isolated by bioassay‐guided fractionation. They were identified as eugenol ( 1 ), methyleugenol ( 2 ), methylisoeugenol ( 3 ), elemicin ( 4 ), myristicin ( 5 ), and safrole ( 6 ). Among these isolates, 4 showed the strongest contact toxicity against L. serricorne adults with an LD₅₀ value of 9.8 μg/adult. Repellency of crude oil and active compounds were also determined. Compounds 1, 2, 4 , and 5 were strongly repellent against the cigarette beetle and exhibited the same level of repellency compared with the positive control, DEET. The results indicate that the essential oil of M. fragrans and its active constituents have potential for development as natural insecticides and repellents to control L. serricorne.     

水菖蒲活性物质β-细辛醚对四种储粮害虫的熏蒸活性

植物性次生物质在植物-害虫的关系中起着非常重要的作用, 植物中的一些成分对害虫具有熏蒸、触杀和驱避等作用。水菖蒲Acorus calamus L.是一种常用中药, 它的主要杀虫活性成分为β-细辛醚。本研究通过室内生测试验研究了水菖蒲根茎提取物β-细辛醚对玉米象Sitophilus zeamais Motschulsky、谷蠹Rhyzopertha dominica (Fabricius)、赤拟谷盗Tribolium castaneum (Herbst)和四纹豆象Callosobruchus maculatus (Fabricius) 4种储粮害虫的熏蒸击倒和致死作用。结果表明: β-细辛醚对4种试虫的熏蒸击倒和致死作用明显。以50 μL/L的浓度处理120 h后, 对玉米象、谷蠹和四纹豆象的击倒作用均达到100%, 而对赤拟谷盗击倒率为50%; 玉米象、谷蠹和四纹豆象的死亡率分别为81.23%, 97.78%和100%, 而赤拟谷盗死亡率仅为8.89%。处理24 h, β-细辛醚对玉米象、谷蠹、赤拟谷盗和四纹豆象的KC50分别为49.38, 102.96, 124.04和1.07 μL/L; 处理120 h, β-细辛醚对玉米象、谷蠹、赤拟谷盗和四纹豆象的LC50分别为17.82, 4.42, 116.48和0.73 μL/L。结果显示水菖蒲根茎提取物β-细辛醚对4种储粮害虫均具有明显的熏蒸效果, 具有开发为储粮害虫熏蒸剂的潜力。     

Toxicity of chlorpyrifos‐methyl to Sitophilus zeamais collected in Korea and biochemical differences

In this study, lethal concentration (LC₅₀) values of chlorpyrifos‐methyl (CPM) were determined for two Korean strains (CBNU and KNU) of Sitophilus zeamais. The two strains had similar susceptibilities (1.70 and 1.86 μg a.i./cm², respectively) to CPM. Carboxylesterase (CE) activity was twice as high in the CBNU strain as in the KNU strain. Lower acetylcholinesterase (AChE) activity was also noted in the latter; however, the activity of glutathione S‐transferase (GST) was twice as high as in the CBNU strain. Gel electrophoresis of CE of crude extracts from adults of the two strains of S. zeamais showed clearly different band patterns, with molecular weights of 60 kDa and 71 kDa in the CBNU and KNU strains, respectively. MALDI‐TOF MS/MS was used to profile small proteins (less than 10 kDa), with results indicating that 206 proteins are expressed differently in the two strains. The peak of interest of 2247.7 m/z was applied to TOF‐TOF MS and its de novo peptide sequence was identified as a tyrosine phosphatase fragment. Phospholipids from the two strains were analyzed and 34 phospholipids were found to be significantly different between strains. Results suggest that the two strains collected from Korea showed different biochemical results, presumably differences in insecticide selection by different living locations.     

Efficacy of cashew kernel extracts in the control of the maize weevil,Sitophilus zeamais (Coleoptera: Curculionidae)

Six different solvents namely: methanol, ethanol, water, acetone, pet-ether or n-hexane was used to extract the essential oils from cashew kernel. The extracted oils were evaluated on Sitophilus zeamais (Motschulsky 1855) for mortality, oviposition and adult emergence effects. The long-term storage and water absorption capacity of the treated maize grains was also investigated. Results showed that the steam distillate was most lethal on S. zeamais. The least potent extracts on S. zeamais were those extracted with methanol and ethanol. The extracts drastically reduced oviposition in S. zeamais. Maize grains treated with steam distillate extract had the lowest water absorption capacity, while the highest water absorption capacity was obtained in grains treated with ethanol and methanol. Extracts of steam distillate, n-hexane, petroleum ether and acetone completely prevented infestation and subsequence damage of the treated maize grains for a period of three months. In the grains treated with the methanol and ethanol extracts, damage of 28.61% and 6.24%, respectively were obtained. The results obtained reveal that extracts of cashew kernel are effective in controlling S. zeamais and could serve as an alternative to synthetic insecticides.     

Repellent and Contact Toxicity of Alpinia officinarum Rhizome Extract against Lasioderma serricorne Adults

The repellent and contact toxicities of Alpinia officinarum rhizome extract on Lasioderma serricorne adults, and its ability to protect stored wheat flour from L. serricorne adults infestation were investigated. The A. officinarum extract exhibited strong repellent and contact toxicities against L. serricorne adults. The toxicities enhanced significantly with the increasing treatment time and treatment dose. The mean percentage repellency value reached 91.3% at class V at the dose of 0.20 μL/cm² after 48 h of exposure. The corrected mortality reached over 80.0% at the dose of 0.16 μL/cm² after 48 h of exposure. The A. officinarum extract could significantly reduce L. serricorne infestation level against stored wheat flour. Particularly, the insect infestation was nil in wheat flour packaged with kraft paper bags coated with the A. officinarum extract at the dose of above 0.05 μL/cm². The naturally occurring A. officinarum extract could be useful for integrated management of L. serricorne.     

Insecticidal activities of essential oil of Callistemon viminalis applied as fumigant and powder against two bruchids

The fumigant and contact toxicity of essential oil (EO) extracted from the leaves of Callistemon viminalis and its aromatized clay powder (ACP) was evaluated against adults of Acanthoscelides obtectus and Callosobruchus maculatus (Coleoptera: Bruchidae). The results obtained for fumigation assays showed that C. maculatus seems to be more susceptible (LC₅₀ = 0.019 μl/cm³) to the vapours of the essential oil than A. obtectus (LC₅₀ = 0.011 μl/cm³) after 12 h exposure. On the other hand, A. obtectus seems to be more susceptible (LD₅₀ = 0.133 μl/g) to the essential oil applied by contact on grains than C. maculatus (LD₅₀ = 0.170 μl/g) after 2 days exposure. The ACP was also very toxic towards the adults of A. obtectus (LD₅₀ = 0.100 μl/g) and C. maculatus (LD₅₀ = 0.098 μl/g) by contact on grains. At the doses of 0.133 μl/g and 0.266 μl/g, mortalities caused by ACP on grains were higher than those caused by the same dose of EO against the two bruchids. It is also established that both the EO and the ACP caused higher inhibition of F₁ progeny production of A. obtectus than that of C. maculatus. The loss of insecticidal activity of the two materials in the course of time has been observed; however, the toxicity of the ACP was more persistent than that of the oil in the course of time when applied on grains. These results suggest that EO from the leaves of C. viminalis can be used as fumigant agent against A. obtectus and C. maculatus. In addition, it could be advisable to use an adsorbent mineral material as carrier of this EO for the prolongation of its insecticidal activity in the course of time.     

Enzyme Inhibition and Antioxidant Activities of Asparagus officinalis L. and Analysis of Its Phytochemical Content by LC/MS/MS

In the study, water, ethanol, methanol, dichloromethane, and acetone extracts of Asparagus officinalis L. were obtained by maceration. DPPH⋅, ABTS⋅⁺, FRAP, and CUPRAC methods determined the antioxidant capacities of all extracts. Moreover, the in vitro effects of extracts on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carbonic anhydrase (CA)-I, CA-II and α-Glycosidase were investigated. At a 10 μg/ml concentration, the extract with the highest Fe³⁺ reduction capacity was ethanol (AE), and the extract with the highest Cu²⁺ reduction capacity was acetone (AA). AE for AChE (IC₅₀=21.19 μg/ml) and α-Glycosidase (IC₅₀: 70.00 μg/ml), methanol (AM) for BChE (IC₅₀=17.33 μg/ml), CA−I and II (IC₅₀=79.65 and 36.09 μg/ml, respectively) showed the most potent inhibition effect. The content analysis of acetone extract was performed with LC/MS-MS, the first three phytochemicals found most were p-Coumaric acid, rutin, and 4-hydroxybenzoic acid (284.29±3.97, 135.39±8.19, and 102.06±5.51 μg analyte/g extract, respectively).     

Larvicidal and Structure–Activity Studies of Natural Phenylpropanoids and Their Semisynthetic Derivatives against the Tobacco Armyworm Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)

The larvicidal activity of 18 phenylpropanoids, 1 – 18 , including phenylpropenoate, phenylpropenal, phenylpropene, and their semisynthetic analogues, were evaluated against the tobacco armyworm, Spodoptera litura (Fab .), to identify promising structures with insecticidal activity. Amongst various phenylpropanoids, isosafrole, a phenylpropene, showed the best activity, with an LC₅₀ value of 0.6 μg/leaf cm², followed by its hydrogenated derivative dihydrosafrole (LC₅₀=2.7 μg/leaf cm²). The overall larvicidal activity of various phenylpropene derivatives was observed in the following order: isosafrole ( 6 )>dihydrosafrole ( 16 )>safrole ( 12 )>anethole ( 4 )>methyl eugenol ( 11 )>eugenol ( 13 )>β‐asarone ( 8 )>dihydroasarone ( 18 )>dihydroanethole ( 15 ). Dihydrosafrole might be a promising compound, although presenting a lower larvicidal activity than isosafrole, because of its better stability and resistance to oxidative degradation (due to the removal of the extremely reactive olefinic bond) in comparison to isosafrole. Such structure–activity relationship studies promote the identification of lead structures from natural sources for the development of larvicidal products against S. litura and related insect pests.     

Hexane extracts from Tephrosia vogelii Hook. f. protect stored maize against the weevil Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

Powdered dried leaves of Tephrosia vogelii (Hook) (Leguminosae: Papilionoideae) were extracted using hexane, acetone, and ethanol. The extracts were tested for their ability to protect stored maize from damage by Sitophilus zeamais Motschulsky, the major maize weevil in Africa. The acetone and ethanol extracts were ineffective, but the hexane extract had a relatively high efficacy, producing within 7 days a slow reduction in adult survival, reduced numbers of eggs laid and reduced numbers of F₁ progeny, resulting in seed damage averaging 8.8% compared with 98.6% in the untreated control after one generation. This hexane extract provided control of S. zeamais at a higher level compared with neem (the botanical control) but at a lower level compared with pirimiphos‐methyl (the synthetic control). These findings are discussed in the context of T. vogelii containing rotenoids.     

Cleome monophylla essential oil and its constituents as tick (Rhipicephalus appendiculatus) and maize weevil (Sitophilus zeamais) repellents

The repellency of the essential oil of the shrubCleome monophylla (Family: Capparidaceae) and identified constituents of the oil were evaluated against the livestock tick,Rhipicephalus appendiculatus and the maize weevil,Sitophillus zeamais. In a tick climbing repellency bioassay, the oil ofC. monophylla exhibited repellency which, at the highest dose, was comparable to that of the commercial arthropod repellent N,N-diethyl toluamide (DEET). In a Y-tube olfactometer bioassay,C. monophylla oil showed higher or comparable repellency againstS. zeamais relative to DEET at all the doses tested. 14 Compounds were identified in theC. monophylla oil by GC, GC-MS and coinjection with authentic samples. Terpenolene was found to occur in largest quantity (14%) followed by 1-α-terpeneol (10%), pentacosane (9%), (α+β)-humulene (8%), phytol (5%) and 2-dodecanone (4%). The most repellent components againstR. appendiculatus andS. zeamais were 1-α-terpeneol and 2-dodecanone. The overall pattern of repellency activity of theC. monophylla constituents with respect to the two arthropods was, however, different. The potential ofC. monophylla in tick and maize weevil control is discussed.