Appl. Entomol. Zool. 45 (3): 425–433 (2010) http://odokon.org/
Molluscicidal and insecticidal potential of monoterpenes on the white garden snail, Theba pisana (Muller) and the cotton leafworm, Spodoptera littoralis (Boisduval)
Samir A. M. ABDELGALEIL* Department of Pesticide Chemistry, Faculty of Agriculture, 21545-El-Shatby, Alexandria University; Alexandria, Egypt (Received 8 February 2010; Accepted 27 April 2010)
Abstract The present article reports the fumigant and contact toxicities of eleven monoterpenes against adults of Theba pisana and third instar larvae of Spodoptera littoralis. The majority of the tested compounds were found to be toxic to both pests with variable degrees of potency. Among the tested monoterpenes, (L)-fenchone showed the highest fumigant toxicity against T. pisana and S. littoralis with LC50 values of 2.51 and 2.27 mg/l, respectively. Myrcene and 1-8-cine- ole exhibited strong fumigant toxicity against T. pisana, while cuminaldehyde, geraniol and ( )-menthol were not ac- tive. On the other hand, 1-8-cineole and ( )-camphor revealed potent fumigant toxicity against S. littoralis. In the contact assay, the tested monoterpenes were more toxic against T. pisana than S. littoralis. Cuminaldehyde (LD50 28.37 m g/snail) was significantly the most effective compound against T. pisana, followed by geraniol and ( )-limonene. Interestingly, eight of the tested monoterpenes were more toxic to adults of T. pisana than methiocarb. The results of the present study suggested that cuminaldehyde, geraniol, ( )-limonene and ( )-camphor could be used as alternative control agents for T. pisana. In addition, (L)-fenchone and 1-8-cineole could be useful as fumigants for control T. pisana and S. littoralis.
Key words: Monoterpenes; fumigant toxicity; contact toxicity; Theba pisana; Spodoptera littoralis
several economic crops, including tree fruits, veg- INTRODUCTION etables and ornamental plants (El-Okda, 1983). White garden snails, Theba pisana Muller (Mol- The Egyptian cotton leafworm, Spodoptera lit- lusca: Gastropoda: Helicidae), feed on a wide vari- toralis Boisduval (Lepidoptera: Noctuidae), is a ety of plants, including cereals, vegetables, fruits, well-known polyphagous pest of various crops (e.g. herbs, and many ornamentals, destroying seeds and cotton, soybeans, alfalfa, pepper, eggplant, tomato, seedlings, stunting growth, and reducing yields. lettuce, strawberry), widely distributed in the Not only do they directly damage the plants they Mediterranean region, the Middle East, and North feed on but the wounds they create allow plant and East Africa (Hosny et al., 1986; Pineda et al., pathogenic fungi to infect plants. The snails can 2007). S. littoralis larvae feed mainly on leaves and also be vectors of various plant pathogens, and stems and can seriously retard growth or reduce their mucus trails can contaminate grains, vegeta- crop production. bles, fruits, and herbs. In large numbers, their bod- Monoterpenes make a class of natural products ies and shells can be contaminants of mechanically containing ten carbons, found in many different harvested crops (Godan, 1983; Barker, 2002). The higher-order plants. These compounds give plants white garden snail is currently a serious agricul- their unique odoriferous properties. They are de- tural pest in many areas of the world, including Eu- rived from the coupling of two isoprenoid units, rope, the USA, the Mediterranean region and Aus- which are made from isopentylpyrophosphate, a tralia, particularly in wet seasons. In Egypt, this precursor in the biosynthesis of cholesterol. These snail is a destructive agricultural animal pest of compounds are usually fragrant oils or low melting
* E-mail: [email protected] DOI: 10.1303/aez.2010.425
425 426 S. A. M. ABDELGALEIL solids, are often found in perfumes and other cos- Chemicals. Eleven monoterpenes, camphene metics, and are commonly used as food additives (95%), ( )-camphor (98%), ( )-carvone (98%), and therapeutic drugs (Tsao and Coats, 1995). The 1-8-cineole (99%), cuminaldehyde (98%), (L)-fen- natural pesticidal properties of some monoterpenes chone (98%), geraniol (98%), ( )-limonene make them useful as potential alternative pest con- (96%), ( )-linalool (95%), ( )-menthol (98%) trol agents as well as good lead compounds for the and myrcene (90%) were purchased from Sigma- development of safe, effective, and fully bio- Aldrich Chemical Co. (Steinheim, Germany). degradable pesticides. Monoterpenes have been Chemical structures of these monoterpenes are shown to possess remarkable pesticidal activities, shown in Fig. 1. Methiocarb (98.9%) was supplied including insecticidal (Isman, 2000; Grodnitzky by Bayer AG (Leverkusen, Germany). All chemi- and Coats, 2002), herbicidal (Duke et al., 2000; cals were of the highest grade and commercially Singh et al., 2002), fungicidal (Wuryatmo et al., available. 2003; Cärdenas-Ortega et al., 2005), and bacterici- Fumigant toxicity assay on T. pisana. Glass dal (Cristani et al., 2007; Cantore et al., 2009) jars of one liter capacity were used as exposure properties. chambers to test the toxicity of monoterpene va- Several studies have described the fumigant and pors against adults of T. pisana. The monoterpenes contact toxicities of monoterpenes against stored were applied to Whatman no. 1 filter paper pieces product insects (Park et al., 2003; Lee et al., 2004; (3 3 cm) attached to the undersurface of the screw Papachristos et al., 2004; Abdelgaleil et al., 2009); caps of the glass jars. The tested concentrations however, no studies have reported the fumigant were 0.25, 0.5, 1, 2.5, 5, 10, 20, 40, 60, 80 and 100 toxicity of monoterpenes against T. pisana and S. mg/l. Liquid monoterpenes were applied without littoralis as well as the contact toxicity against S. dilution while solid monoterpenes (camphene, ( )- littoralis. El-Zemity (2001) stated that some camphor and ( )-menthol) were dissolved in ace- monoterpenes, such as α-terpineol, pulegone, anisole, thymol and eugenol, revealed contact toxi- city against T. pisana. Taking into account the lack of literature on the activity of monoterpenes against T. pisana and S. littoralis and the urgent need for new snail control agents due to the few commercially available molluscicides, this study aimed to evaluate the fumigant and contact toxici- ties of 11 monoterpenes belonging to different classes against T. pisana and S. littoralis.
MATERIALS AND METHODS Test organisms. Adult terrestrial snails (16 0.5 mm shell diam.), Theba pisana (Muller), were collected from the Faculty of Agriculture Garden, Alexandria, Egypt in April, 2008. The snails were kept under laboratory conditions at 26 2°C in ventilated glass jars for two weeks before bioassay and were fed a diet of fresh lettuce leaves (Lactuca sativa L.). A susceptible strain of Spodoptera lit- toralis (Boisd) was obtained from the Bioassay Laboratory, Faculty of Agriculture, Alexandria University. The colony was reared under laboratory conditions on caster bean leaves, Ricinus commu- nis L. (Euphorbiaceae), at 26 2°C and 70 5% r.h. (El-Defrawi et al., 1964). Fig. 1. The chemical structures of monoterpenes. Pesticidal Activity of Monoterpenes 427 tone before treating the filter papers. After the ad- of concentrations ranging from 0.2 to 100 mg/l. At dition of volatile monoterpenes and the complete least six concentrations for each monoterpene were evaporation of acetone (2 min), the jars were tested and each concentration was in triplicate. The sealed. A similar set-up but without volatile larvae were fed on fresh castor bean leaves. The monoterpenes served as a control. For each treat- mortality percentages were recorded after 24-h ment, four replicates with 5 snails on each one treatment. LC50 values were calculated as previ- were maintained. The snails were fed on fresh let- ously described. tuce leaves during the experiment. Mortality was Contact toxicity assay on S. littoralis. Topical determined after 24-h exposure. Test snails were application assay was used to evaluate the larvici- considered dead if no response was observed after dal activity of the monoterpenes against third instar being touched with a thin needle (WHO, 1965). larvae of S. littoralis. Concentrations of the mono-
LC50 (lethal concentration to kill 50% of the popu- terpenes were prepared in acetone. One microliter lation relative to control) values were calculated by of test solution was applied to the dorsum of larvae probit analysis (Finney, 1971). by a microapplicator. The larvae were treated with Contact toxicity assay on T. pisana. The effi- a single dose of 1 mg/larva. Three replicates of 10 ciency of monoterpenes was evaluated on adult larvae each were maintained for each monoterpene snails of T. pisana as described by Hussein et al. and control treatment. Treated larvae were then (1994) and El-Zemity and Radwan (1999) with placed in glass cups and supplied with fresh castor some modifications. Stock solutions of monoter- bean leaves. The percentages of mortality were penes and methiocarb, a standard molluscicide, recorded after 24-h treatment. were prepared in dimethyl sulfoxide (DMSO). The Statistical analysis. The mortality of each dose snails were treated with doses of 5, 10, 20, 40, 60, and⁄or concentration was calculated after 24-h 80, 100, 200, 400, 600, 800 and 1,000 mg/snail. treatment as the mean of three replicates. The mor- These doses contained in 5 ml DMSO solution tality data were subjected to probit analysis were gently applied to the surface of the snail body (Finney, 1971) to obtain the LD50 and LC50 values, inside the shell using a micropipette. Three repli- using SPSS 12.0 (SPSS, Chicago, IL, USA). The cates (five snails in each) of each concentration values of LD50 and LC50 were considered signifi- were used. Control snails were treated with the cantly different if the 95% confidence limits did same volumes of DMSO. The treated snails were not overlap. The contact toxicity data of S. littoralis placed in 0.3 l glass jars. The jars were covered larvae were analyzed by one-way analysis of vari- with cheesecloth fastened by rubber bands to pre- ance. Mean separations were performed by the Stu- vent the escape of snails and to ensure proper ven- dent-Newman-Keuls (SNK) test and differences at tilation. The snails were fed on fresh lettuce leaves p 0.05 were considered significant. during the experiment. Methiocarb was used as a reference molluscicide for comparison. The mor- RESULTS tality percentages were recorded after 24-h treat- ment. LD50 (lethal dose to kill 50% of the popula- Fumigant toxicity of monoterpenes against adults tion relative to control) values were calculated by of T. pisana probit analysis (Finney, 1971). The results of fumigant toxicity of monoterpenes Fumigant toxicity assay on S. littoralis. Third against adults of T. pisana in terms of lethal con- instar larvae of S. littoralis were used to assess the centration (LC50) values as well as other statistical fumigant toxic action of the tested monoterpenes. parameters generated by linear regression analysis Ten larvae were placed in each glass jars of 0.3 l are shown in Table 1. All of the tested monoter- capacity. Initial tests were done to establish the ap- penes revealed a pronounced toxic effect, except propriate concentrations of each monoterpene. Dif- for cuminaldehyde, geraniol and ( )-menthol. The ferent amounts of the tested monoterpenes were tested monoterpenes can be divided into four applied to Whatman no. 1 filter paper pieces (2 3 groups based on their LC50 values. There were sig- cm) attached to the undersurface of screw caps of nificant differences between the mortality levels of the glass jars. Caps were then screwed tightly onto monoterpene groups. The first group of monoter- the jars. The monoterpenes were tested at a series penes ((L)-fenchone, myrcene and 1-8-cineole) ex- 428 S. A. M. ABDELGALEIL
Table 1. Fumigant toxicity of monoterpenes against adults of Theba pisana
95% Confidence limits (mg/l ) LC a Monoterpene 50 Slope S.E.b Intercept S.E.c (c 2)d (mg/l) Lower Upper
Camphene 33.53 30.44 36.61 4.90 0.51 7.48 0.80 1.72 ( )-Camphor 7.98 7.14 8.82 3.89 0.46 3.51 0.44 0.69 ( )-Carvone 27.01 22.77 31.60 1.99 0.20 2.85 0.31 3.15 1-8-Cineole 4.17 2.06 6.31 5.04 0.42 3.12 0.29 9.41 Cuminaldehyde 100 (L)-Fenchone 2.51 2.29 2.73 4.22 0.33 1.68 0.16 0.11 Geraniol 100 ( )-Limonene 8.39 7.89 8.97 5.46 0.67 5.04 0.61 2.52 ( )-Linalool 7.72 6.90 8.93 2.60 0.45 2.31 0.38 2.29 ( )-Menthol 100 Myrcene 3.88 3.40 4.35 2.75 0.27 1.62 0.20 3.20
a Lethal concentration causing 50% mortality after 24 h. b Slope of the concentration-mortality regression line standard error. c Intercept of the regression line standard error. d Chi square value. Table 2. Contact toxicity of monoterpenes against adults of Theba pisana
95% Confidence limits (mg/snail) LD a Monoterpene 50 Slope S.E.b Intercept S.E.c (c 2)d (mg/snail) Lower Upper
Camphene 1,000 ( )-Camphor 89.15 76.84 103.04 2.11 0.25 4.12 0.50 2.47 ( )-Carvone 132.18 104.18 158.71 2.13 0.23 4.52 0.55 1.02 1-8-Cineole 223.44 181.15 267.35 1.74 0.19 4.08 0.49 2.00 Cuminaldehyde 28.37 21.44 34.09 1.76 0.29 2.56 0.48 0.27 (L)-Fenchone 135.36 111.20 137.66 2.59 0.27 5.53 0.63 3.38 Geraniol 42.29 36.94 47.80 2.54 0.26 4.12 0.45 3.18 ( )-Limonene 60.27 52.36 66.51 3.55 0.62 6.32 1.15 0.70 ( )-Linalool 130.51 99.26 158.65 1.99 0.29 4.21 0.66 0.33 ( )-Menthol 99.44 57.97 138.32 1.26 0.19 2.51 0.48 0.12 Myrcene 1,000 Methiocarb 188.68 127.18 326.96 0.72 0.10 1.63 0.21 4.66
a Lethal dose causing 50% mortality after 24 h. b Slope of the concentration-mortality regression line standard error. c Intercept of the regression line standard error. d Chi-square value.
hibited the strongest toxicity with LC50 values of LC50 values greater than 100 mg/l. 2.51, 3.88 and 4.17 mg/l, respectively. The second group of compounds (( )-linalool, ( )-camphor Contact toxicity of monoterpenes against adults and ( )-limonene) also had an excellent toxic ef- of T. pisana fect as LC50 values for these compounds were less The contact toxic effect of the 11 tested than 10 mg/l. In the third group, compounds ( )- monoterpenes and methiocab, a recommended carvone and camphene showed moderate fumigant molluscicide, on the adults of T. pisana was evalu- toxicity with LC50 values less than 50 mg/l. The ated using a topical application assay. Table 2 sum- fourth group of compounds (cuminaldehyde, marizes the results of this assay expressed as lethal geraniol and ( )-menthol) were less effective with dose values (LD50). The monoterpenes showed Pesticidal Activity of Monoterpenes 429
Table 3. Fumigant toxicity of monoterpenes against third instar larvae of Spodoptera littoralis
95% Confidence limits (mg/l) LC a Monoterpene 50 Slope S.E.b Intercept S.E.c (c 2)d (mg/l ) Lower Upper
Camphene 100 ( )-Camphor 5.61 2.72 7.47 4.07 0.47 3.05 0.39 4.96 ( )-Carvone 19.48 8.72 30.17 5.22 0.42 6.74 0.57 10.55 1-8-Cineole 4.34 0.06 5.86 4.92 0.56 3.14 0.43 7.44 Cuminaldehyde 100 (L)-Fenchone 2.27 2.02 2.55 3.14 0.24 1.12 0.13 1.05 Geraniol 100 ( )-Limonene 11.36 10.58 12.24 5.29 0.55 5.58 0.57 0.17 ( )-Linalool 100 ( )-Menthol 9.36 7.44 11.53 1.72 0.21 1.67 0.24 0.27 Myrcene 100
a Lethal concentration causing 50% mortality after 24 h. b Slope of the concentration-mortality regression line standard error. c Intercept of the regression line standard error. d Chi-square value. varying degrees of toxicity to snail adults. Among and myrcene) were not active as they showed LC50 the monoterpenes, cuminaldehyde (LD50 28.37 values greater than 100 mg/l. (L)-Fenchone (2.27 µg/snail) was significantly the most potent com- mg/l) was significantly the most potent compound, pound followed by geraniol (LD50 42.29 µg/ followed by 1-8-cineole (4.34 mg/l) and ( )-cam- snail). Similarly, the three compounds, ( )- phor (5.61 mg/l). limonene, ( )-camphor and ( )-menthol, showed a strong toxic effect with LD50 values less than 100 Contact toxicity of monoterpenes against third µg/snail. Meanwhile, ( )-linalool, ( )-carvone instar larvae of S. littoralis and (L)-fenchone had good toxicity, and 1-8-cine- The mortality percentages of third instar larvae ole had moderate toxicity, while camphene and of S. littoralis caused by the tested monoterpenes at myrcene were not active. It was observed that five a single dose of 1 mg/larva are shown in Fig. 2. In of the tested monoterpenes (cuminaldehyde, geran- general, all of the tested compounds possessed var- iol, ( )-limonene, ( )-camphor and ( )-menthol) ious degrees of contact toxicity. Geraniol and were significantly more toxic to adults of T. pisana cuminaldehyde were significantly the most toxic than the reference molluscicide, methiocarb (95% compounds, with mortality of 76.7% and 70.0%, confidence limits did not overlap), while four repetitively. The monoterpenes of ( )-menthol, monoterpenes (( )-linalool, ( )-carvone, (L)-fen- ( )-carvone and (L)-fenchone exhibited moderate chone, and 1-8-cineole) were comparable based on toxicity whereas myrcene and camphene had less
LD50 values (overlapping 95% confidence limits). toxicity.
Fumigant toxicity of monoterpenes against third DISCUSSION instar larvae of S. littoralis Table 3 shows the fumigant toxic effect of the The present results demonstrate that the tested monoterpenes against the third instar larvae monoterpenes tested have varying degrees of mol- of S. littoralis. The results demonstrated that the luscicidal activity against adults of T. pisana. It monoterpenes had different toxicity levels. Among was found that the vapors of eight out of 11 the tested compounds, six compounds ((L)-fen- monoterpenes tested possessed marked molluscici- chone, 1-8-cineole, ( )-camphor, ( )-menthol, dal activity. Of these, (L)-fenchone, myrcene and 1- ( )-limonene and ( )-carvone) had potent toxicity 8-cineole had the highest vapor toxicity with a based on LC50 values. In contrast, five compounds LC50 less than 5 mg/l. Moreover, nine of the tested (camphene, cuminaldehyde, geraniol, ( )-linalool monoterpenes showed strong contact toxicity 430 S. A. M. ABDELGALEIL
Fig. 2. Contact toxicity of monoterpenes against third instar larvae of Spodoptera littoralis at 1mg/larva. Error bars represent the standard errors of the mean of three replicates. Bars headed by different letters are significantly different (p 0.05). Student- Newman-Keuls (SNK) test was preformed on the data. against the snail with cuminaldehyde, geraniol and third instar larvae of S. littoralis revealed that six ( )-limonene being the most potent compounds. of the monoterpenes tested showed strong toxicity. Interestingly, eight of the monoterpenes tested Among these compounds, (L)-fenchone, 1-8-cine- were more toxic to T. pisana than the reference ole and ( )-camphor were the most potent, with molluscicide, methiocarb. For example, the contact LC50 values ranging from 2.27 to 5.61 mg/l. Sev- toxicities of cuminaldehyde, geranial and ( )- eral studies have reported the fumigant toxicity of limonene were 6.6, 4.5 and 3.1 times, respectively, some monoterpenes against other insect species greater than the toxicity of methiocarb. In the liter- (Kim and Ahn, 2001; Lee et al., 2003; Park et al., ature, there are no studies on the fumigant toxicity 2003; Lee et al., 2004; Papachristos et al., 2004; of monoterpenes against the white garden snail. In Abdelgaleil et al., 2009). In contact toxicity assay, this respect, this is a first report on the fumigant the monoterpenes tested had moderate or weak ac- toxicities of monoterpenes to T. pisana; however, tivity against third instar larvae of S. littoralis; in our previous study, the essential oils of Citrus therefore, the LD50 were not estimated for reticulata, Schinus terebenthifolius, Mentha micro- monoterpenes in this experiment. Although no re- phylla, Lantana camara and Eucalyptus camaldu- port was found in the literature on the fumigant lensis were found to possess fumigant toxicity and contact toxic effects of monoterpenes against against this snail (El-Aswad and Abdelgaleil, S. littoralis, some essential oils were reported to 2008). On the other hand, some essential oils, such have insecticidal activity against this insect as E. camaldulensis, Lavandula entate, Ruta (Pavela, 2005; El-Aswad and Abdelgaleil, 2008). chalepensis, M. microphylla and L. camara were Comparing the toxicities of monoterpenes on described to possess contact toxicity against adults T. pisana and S. littoralis revealed that some of this snail (Hussein, 2005; Abdelgaleil and compounds, such as (L)-fenchone, 1-8-cineole, Badawy, 2006). In addition, the contact toxicities ( )-limonene, ( )-camphor, ( )-carvone, showed of monoterpenes (i.e., a -terpineol, pulegone, strong fumigant activity against both pests anisole, thymol and eugenol) were reported (El- while cuminaldehyde and geraniol were not toxic Zemity, 2001). It was clear that the molluscicidal (LC50 100 mg/l). Although linalool and myrcene activity of the tested monoterpenes in the present showed potent fumigant toxicity against T. pisana, work was more potent than those of the essential they were not active against S. littoralis. In con- oils and monoterpenes previously reported. trast, ( )-menthol was strongly active against S. The results of fumigant toxicity experiments on littoralis, but not active against T. pisana. In gen- Pesticidal Activity of Monoterpenes 431 eral, the test monoterpenes had greater contact tox- against houseflies (Rice and Coats, 1994), stored icity against T. pisana than S. littoralis. Similarly, it product insects (Lee et al., 2003) and Colorado po- has been found that the toxicity of monoterpenes tato beetle (Kordali et al., 2007); however, it has varied with the insect species (Lee et al., 2004; Ab- been observed that among one class of monoter- delgaleil et al., 2009). The observed differential penes, the toxicity varied. For example, in mono- pesticidal activity seems to be the result of inherent terpene hydrocarbons, ( )-limonene showed interspecific differences, suggesting a species-spe- strong contact toxicity against T. pisana but cam- cific mode of action. Moreover, these different re- phene and myrcene were not toxic. Likewise, in sponses of T. pisana and S. littoralis to monoter- monoterpene alcohols, ( )-linalool revealed potent penes could be attributed to the degree of sensitiv- fumigant toxicity against T. pisana but geraniol and ity of the targeted sites or/and the activity and the ( )-menthol were not active. Moreover, (L)-fen- availability of detoxification enzymes. chone was the most potent fumigant toxicant The results indicate that the toxicity assay has a among ketones against both pests while ( )-cam- great impact on the activity of the tested monoter- phor was more active than (L)-fenchone in contact penes. In the case of T. pisana, geraniol and cumi- toxicity against T. pisana. In a recent study re- naldehyde showed the strongest toxicity in the con- ported by our research group, 1-8-cineole was the tact assay but were not active in the fumigant assay. most potent fumigant against Tribolium costaneum In contrast, (L)-fenchone and 1-8-cineole were the and Sitophilus oryzae, but was not active as a con- most potent fumigants among the tested com- tact toxicant (Abdelgaleil et al., 2009). Similar re- pounds, whereas they showed weak contact toxic- sults were found in the present study as 1-8-cineole ity. In addition, myrcene had strong fumigant toxic- was a potent fumigant toxicant against T. pisana ity but was not active in contact toxicity. On the and S. littoralis but showed weak contact toxicity other hand, six monoterpenes ((L)-fenchone, 1-8- against both pests. cineole, ( )-camphor, ( )-menthol, ( )-limonene Despite abundant research on the pesticidal ac- and ( )-carvone) had higher fumigant toxicity to- tivity of monoterpenes, the modes of action of wards S. littoralis than contact toxicity. This find- monoterpenes are not well understood. It has been ing indicates that monoterpenes may penetrate via reported that monoterpenes were effective in- the respiratory system more effectively than the in- hibitors of acetylcholinesterases (AChEs) from sect cuticle and interact rapidly with insect physio- eels, houseflies, and bovine erythrocytes (Gracza logical functions. Previously, it has been reported 1985; Grundy and Still, 1985; Miyazawa et al., that the toxicity of monoterpenes against stored 1997; Ryan and Byrne, 1998; Picollo et al., 2008); product insects differed based on the assay method however, Lee et al. (2001) and Abdelgaleil et al. used (Prates et al., 1998; Park et al., 2003). (2009) reported that monoterpene toxicity was not The tested monoterpenes consisted of five necessarily correlated with the ability to inhibit groups: monoterpene hydrocarbons that included AChE activity. Another researcher has demon- camphene, ( )-limonene and myrcene, and alco- strated that some monoterpenes bind to oc- hols that included geraniol, linalool and ( )-men- topamine receptors (Enan, 2001). It has been also thol, ketones that included ( )-camphor (98%), found that monoterpenes had good binding affinity ( )-carvone and (L)-fenchone, aldehydes that in- for the GABA-gated chloride ion channel in the cluded cuminaldehyde, and oxides that included 1- mouse brain (Hold et al., 2000). De-Oliveira et al. 8-cineole. The analysis of the results of the present (1997) suggested that some monoterpenes may in- study revealed the influence of the monoterpene hibit cytochrome P450-dependent monooxyge- class on the fumigant and contact toxicities of nases. These studies suggest that the target sites of monoterpenes against T. pisana and S. littoralis. the modes of action of monoterpenes vary, which Thus, a ketone monoterpene, (L)-fenchone, was the may be attributed to their chemical diversity. most potent fumigant toxicant against both pests, In conclusion, natural pesticides are a desirable while an aldehyde (cuminaldehyde) and an alcohol alternative to synthetic pesticides because they may (geraniol) were the most effective contact toxi- degrade more rapidly than synthetic pesticides, cants. Similarly, it has been found that some ke- may be more specific in their action, and have low tones were more effective fumigants than alcohols toxicity to mammals and wide public acceptance. 432 S. A. M. ABDELGALEIL
The remarkable fumigant toxicity of some test El-Okda, M. M. K. (1983) Terrestrial snails and slugs (Pul- monoterpenes against T. pisana and S. littoralis as monata) destructive mollusca in ornamental plantages in well as the promising contact toxicity of these Alexandria, Egypt. In Proceedings of the 5th Arab Pesti- cide Conference. vol. 2. Tanta University, pp. 369–378. monoterpenes against T. pisana demonstrated in El-Zemity, S. R. (2001) Molluscicidal activity of some natu- this study suggested that some of the test monoter- rally occurring compounds and their blends against land penes have potential for use in the control of T. snails. J. Pest Cont. Environ. Sci. 9: 39–50. pisana and S. littoralis, particularly in the green- El-Zemity, S. R. and M. A. Radwan (1999) Synthesis and houses; however, further studies are required to structure-activity relationship for anticipated molluscici- evaluate their mammalian toxicity, phytotoxicity dal activity of some 2-amino-5-substituted pyridine deriv- atives. Pestic. Sci. 55: 1203–1209. and modes of action. Enan, E. (2001) Insecticidal activity of essential oils: Oc- topaminergic sites of action. Comp. Biochem. Phys. C REFERENCES 130: 325–337. Abdelgaleil, S. A. M. and M. E. I. Badawy (2006) Acaricidal Finney, D. J. (1971) Probit Analysis. third ed. Cambridge and molluscicidal potential of three essential oils isolated University Press, London. 318 pp. from Egyptian plants. J. Pest Cont. Environ. Sci. 14: Godan, D. (1983) Pest Slugs and Snails, Biology and Con- 35–46. trol. Springer-Verlag, Berlin. 443 pp. Abdelgaleil, S. A. M., M. I. E. Mohamed, M. E. I. Badawy and Gracza, L. (1985) Molecular pharmacological investigation S. A. A. El-arami (2009) Fumigant and contact toxici- of medicinal plant substances II. Inhibition of acetyl- ties of monoterpenes to Sitophilus oryzae (L.) and Tri- cholinesterase by monoterpene derivatives in vitro. Z. bolium castaneum (Herbst) and their inhibitory effects on Naturforsch. 40c: 151–153. acetylcholinesterase activity. J. Chem. Ecol. 35: 518– Grodnitzky, J. A. and J. R. Coats (2002) QSAR Evaluation of 525. monoterpenoids’ insecticidal activity. J. Agric. Food Ann. (1965) Molluscicidal screening and evaluation. WHO Chem. 50: 4576–4580. Bull. 38: 507–581. Grundy, D. L. and C. C. Still (1985) Inhibition of acetyl- Barker, G. M. (2002) Mollusks as Crop Pests. CABI Pub- cholinesterase by pulegone-1,2-epoxide. Pestic. Biochem. lishing, Wallingford, Oxon, UK. 441 pp. Physiol. 3: 383–388. Cantore, P. L., V. Shanmugaiah and N. S. Iacobellis (2009) Hold, K. M., N. S. Sirisoma, T. Ikeda, T. Narahashi and J. E. Antibacterial activity of essential oil components and Casida (2000) R-Thujone (the active component of ab- their potential use in seed disinfection. J. Agric. Food sinthe): g-Aminobutyric acid type A receptor modulation Chem. 57: 9454–9461. and metabolic detoxification. P. Natl. Acad. Sci. USA Cärdenas-Ortega, N. C., M. A. Zavala-Sänchez, J. R. Aguirre- 97: 3826–3831. Rivera, C. Peärez-Gonzälez and S. Peärez-Gutienärrez Hosny, M. M., C. P. Topper, G. G. Moawad and G. B. El- (2005) Chemical composition and antifungal activity of Saadany (1986) Economic damage thresholds of essential oil of Chrysactinia mexicana Gray. J. Agric. Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) Food Chem. 53: 4347–4349. on cotton in Egypt. Crop Protect. 5: 100–104. Cristani, M., M. D’arrigo, G. Mandalari, F. Castelli, M. G. Hussein, H. I. (2005) Composition of essential oils isolated Sarpietro, D. Micieli, V. Venuti, G. Bisignano, A. Saija from three plant species and their molluscicidal activity and D. Trombetta (2007) Interaction of four monoter- against Theba pisana snails. J. Pest Cont. Environ. Sci. penes contained in essential oils with model membranes: 13: 15–24. Implications for their antibacterial activity. J. Agric. Hussein, H. I., A. Kamel, M. Abou-Zeid, A. H. El-Sebae and Food Chem. 55: 6300–6308. M. A. Salah (1994) Uscharin, the most potent mollusci- De-Oliveira, A. C., L. F. Ribeiro-Pinto and J. R. Paumgartten cidal compound tested against land snails. J. Chem. (1997) In vitro inhibition of CYP2B1 monooxygenase Ecol. 20: 135–140. by myrcene and other monoterpenoid compounds. Toxi- Isman, M. B. (2000) Plant essential oils for pest and disease col. Lett. 92: 39–46. management. Crop Protect. 19: 603–608. Duke, S. O., J. G. Romagni and F. E. Dayan (2000) Natural Kim, D. H. and Y. J. Ahn (2001) Contact and fumigant activ- products as sources for new mechanisms of herbicidal ac- ities of constituents of Foeniculum vulgare fruit against tion. Crop Protect. 19: 583–589. three coleopteran stored-product insects. Pest Manag. El-Aswad, A. F. and S. A. M. Abdelgaleil (2008) Insectici- Sci. 57: 301–306. dal, antifeedant and molluscicidal potential of essential Kordali, S., M. Kesdek and A. Cakir (2007) Toxicity of oils extracted from Egyptian plants. J. Egy. Soc. Toxi- monoterpenes against larvae and adults of Colorado po- col. 38: 81–91. tato beetle, Leptinotarsa decemlineata Say (Coleoptera: El-Defrawi, M. E., A. Tappozada, N. Mansour and M. Zeid Chrysomelidae). Ind. Crops Prod. 26: 278–297. (1964) Toxicological studies on the Egyptian cotton Lee, B.-H., W.-S. Choi, S.-E. Lee and B.-S. Park (2001) Fu- leafworm Prodenia litura L. Susceptibility of different migant toxicity of essential oils and their constituent larval instars of Prodenia to insecticides. J. Econ. Ento- compounds towards the rice weevil, Sitophilus oryzae mol. 57: 591–593. (L.). Crop Protect. 20: 317–320. Pesticidal Activity of Monoterpenes 433
Lee, B.-H., P. C. Annis, F. Tumaaliia and W.-S. Choi (2004) Pineda, S., M. I. Schneuder, G. Smagghe and A.-M. Martinez Fumigant toxicity of essential oils from the Myrtaceae (2007) Lethal and sublethal effects of Methoxyfenozide family and 1,8-cineole against 3 major stored-grain in- and Spinosad on Spodoptera littoralis (Lepidoptera: Noc- sects. J. Stored Prod. Res. 40: 553–564. tuidae). J. Econ. Entomol. 100: 773–780. Lee, S., C. J. Peterson and J. R. Coats (2003) Fumigation Prates, H. T., J. P. Santos, T. M. Maquil, J. D. Fabris, A. B. toxicity of monoterpenoids to several stored product in- Oliveira and J. E. Foster (1998) Insecticidal activity of sects. J. Stored Prod. Res. 39: 77–85. monoterpenes against Rhyzopertha dominica (F.) and Tri- Miyazawa, M., H. Watanabe and H. Kameoka (1997) Inhibi- bolium castaneum (Herbst). J. Stored Prod. Res. 34: tion of acetylcholinesterase activity by monoterpenoids 243–249. with a P-menthane skeleton. J. Agric. Food Chem. 45: Rice, P. J. and J. R. Coats (1994) Insecticidal properties of 677–679. several monoterpenoids to the house fly (Diptera: Musci- Papachristos, D. P., K. I. Karamanoli, D. C. Stamopoulos and dae), red flour beetle (Coleoptera: Tenebrionidae), and U. Menkissoglu-Spiroudi (2004) The relationship be- southern maize rootworm (Coleoptera: Chrysomelidae). tween the chemical composition of three essential oils J. Econ. Entomol. 87: 1172–1179. and their insecticidal activity against Acanthoscelides ob- Ryan, M. F. and O. Byrne (1998) Plant-Insect coevolution tectus (Say). Pest Manag. Sci. 60: 514–520. and inhibition of acetylcholinesterase. J. Chem. Ecol. Park, I. K., S. G. Lee, D. H. Choi, J. D. Park and Y. J. Ahn 14: 1965–1975. (2003) Insecticidal activities of constituents identified Singh, H. P., D. R. Batish and R. K. Kohli (2002) Allelo- in the essential oil from leaves of Chamaecyparis obtusa pathic effect of two volatile monoterpenes against bill against Callosobruchus chinensis (L.) and Sitophilus goat weed (Ageratum conyzoides L.). Crop Protect. 21: oryzae (L.). J. Stored Prod. Res. 39: 375–384. 347–350. Pavela, R. (2005) Insecticidal activity of some essential oils Tsao, R. and J. R. Coats (1995) Starting from nature to make against larvae of Spodoptera littoralis. Fitoterapia 76: better insecticides. Chemtech 25: 23–28. 691–696. Wuryatmo, E., A. Klieber and E. S. Scott (2003) Inhibition Picollo, M. I., A. C. Toloza, G. Mougabure Cueto, J. Zygadlo of citrus postharvest pathogens by vapor of citral and re- and E. Zerba (2008) Anticholinesterase and pediculici- lated compounds in culture. J. Agric. Food Chem. 51: dal activities of monoterpenoids. Fitoterapia 79: 271– 2637–2640. 278.