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Evaluation of the repellent effects of Nepeta parnassica extract, essential oil, and its major nepetalactone metabolite against mosquitoes
Abstract and Figures
The dichloromethane-methanol extract, the essential oil obtained by hydrodistillation from Nepeta parnassica, and the isolated 4aα,7α,7aβ-nepetalactone were evaluated for their repellent effect against the mosquitoes Aedes (Stegomyia) cretinus Edwards and Culex pipiens pipiens biotype molestus Forskål. The chemical analysis of N. parnassica essential oil, dominated by oxygenated monoterpenes (87 %), revealed 4aα,7α,7aβ-nepetalactone (36.8 %), 1,8-cineole (25.5 %), and 4aα,7β,7aβ-nepetalactone (11.1 %) as the major constituents. The results of the insect bioassays showed that the essential oil and the dichloromethane-methanol extract of N. parnassica were very active against Aedes cretinus for up to 3 h and against Culex pipiens for up to 2 h post application. The isolated 4aα,7α,7aβ-nepetalactone showed very high mosquito repellency for periods of at least 2 h against both species.
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... Considering the function of rubbing behavior in cats, we suggested that plant iridoids have bioactivities other than the induction of the iridoid response to cats. Some of the plant iridoids are known to be repellent to a broad range of insects, including nonherbivores such as Aedes and Culex mosquitoes and stable flies (Stomoxys) (Birkett et al., 2011;Feaster et al., 2009;Gkinis et al., 2014;Melo et al., 2021;Reichert et al., 2019;Zhu et al., 2012). We also found that nepetalactol acts as a repellent against mosquitoes, Aedes albopictus, which are the most common mosquito in Japan and bite animals in the early morning and late afternoon when crepuscular cats are mostly at their peak of activity. ...
... It is reported that nepetalactone has a repellent activity to Ae. aegypti which is a common vector of yellow fever, dengue, and Zika viruses (Benelli & Mehlhorn, 2016;Birkett et al., 2011;Gkinis et al., 2014;Zhu & Zeng, 2006). Our studies reveal the repellent effect of nepetalactol on Ae. albopictus mosquitos, carrying Dirofilaria immitis, which infects the heart and pulmonary arteries of cats (Traversa & Di Cesare, 2014). ...
... Previous studies have reported mosquito-repelling activity of individual iridoids such as nepetalactone, nepetalactol, and dihydronepetalactone (Birkett et al., 2011;Feaster et al., 2009;Gkinis et al., 2014;Melo et al., 2021;Reichert et al., 2019;Uenoyama et al., 2021;Zhu et al., 2012), but have not examined responses to the iridoid cocktails. Thus, we compared the repellency of the synthetic iridoid cocktails that correspond to extracts from intact and manually crumpled and torn silver vine leaves. ...
Cats show a characteristic response to catnip (Nepeta cataria) and silver vine (Actinidia polygama), which comprises licking, chewing, rubbing, and rolling. This response is induced by plant iridoids: nepetalactone (catnip) and dihydronepetalactone, isodihydronepetalactone, iridomyrmecin, and isoiridomyrmecin (silver vine). However, its biological significance had remained undetermined. In this chapter, we review the behavioral significance of this feline response. Nepetalactol was isolated as a potent bioactive compound from silver vine. Nepetalactol-induced rubbing and rolling behavior transfers nepetalactol to feline fur. Nepetalactol has also mosquito repellent bioactivity, and as a consequence, its transfer to the feline’s fur protects cats from mosquito bites. Licking and chewing the plants damages the leaves, which promotes airborne emission of iridoids from the plants and diversifies the iridoids in silver vine. Although both the amount and composition of iridoids considerably differ between these plants, cats show a comparably prolonged duration of the response to the low level of a complex cocktail of iridoids in damaged silver vine and the high level of nepetalactone in damaged catnip. In conclusion, the silver vine and catnip response contributes to chemical pest defense in cats, which provides an important example of how animals utilize plant metabolites for their pest defense.
... The consistent expression of such a characteristic response to nepetalactol suggests that the response has an important adaptive function for cats. On the basis of reports that nepetalactone from catnip has mosquito-repellent activity when applied to humans (27)(28)(29), we hypothesized that the characteristic rubbing and rolling against plants allows cats to transfer nepetalactol or nepetalactone onto the fur for chemical defense against mosquitoes and possibly also against other biting arthropods. In this study, we tested whether nepetalactol is repellent to Aedes albopictus, a mosquito common in Japan and China (30). A. albopictus avoided both silver vine leaves (five leaves, containing approximately 100 g of nepetalactol) and nepetalactol alone (50 g, 200 g, and 2 mg) compared to a solvent control, when each was placed separately into test cages that had shelters into which A. albopictus could move ( Fig. 4A; ANOVA, effect of stimulus F 4,15 = 79.93, ...
... Although we only tested for a repellent effect on A. albopictus in this study, we might also expect nepetalactol to be repellent to other mosquito species including A. aegypti, which is a common vector of yellow fever, dengue, and Zika viruses (42), consistent with the broad repellence of nepetalactone across a range of mosquito and other biting arthropods (27)(28)(29). Our findings suggest that nepetalactol may be a new natural candidate repellent to help reduce mosquito problems in human society. ...
Domestic cats and other felids rub their faces and heads against catnip ( Nepeta cataria ) and silver vine ( Actinidia polygama ) and roll on the ground as a characteristic response. While this response is well known, its biological function and underlying mechanism remain undetermined. Here, we uncover the neurophysiological mechanism and functional outcome of this feline response. We found that the iridoid nepetalactol is the major component of silver vine that elicits this potent response in cats and other felids. Nepetalactol increased plasma β-endorphin levels in cats, while pharmacological inhibition of μ-opioid receptors suppressed the classic rubbing response. Rubbing behavior transfers nepetalactol onto the faces and heads of respondents where it repels the mosquito, Aedes albopictus . Thus, self-anointing behavior helps to protect cats against mosquito bites. The characteristic response of cats to nepetalactol via the μ-opioid system provides an important example of chemical pest defense using plant metabolites in nonhuman mammals.
... In another study, the EO of Nepeta parnassica (Lamiales: Lamiaceae), having eucalyptol as the main constituent, displayed a good repellency against Ae. cretinus and Culex pipiens (Diptera: Culicidae) for 3 h and 2 h, respectively [34]. ...
Repellents are effective personal protective means against outdoor biting mosquitoes. Repellent formulations composed of EOs are finding increased popularity among consumers. In this study, after an initial screening of 11 essential oils (EOs) at the concentration of 33 μg/cm2, five of the most repellent EOs, Perovskia atriplicifolia, Citrus reticulata (fruit peels), C. reticulata (leaves), Mentha longifolia, and Dysphania ambrosioides were further investigated for repellent activity against Aedes aegypti mosquitoes in time span bioassays. When tested at the concentrations of 33 μg/cm2, 165 μg/cm2 and 330 μg/cm2, the EO of P. atriplicifolia showed the longest repellent effect up to 75, 90 and 135 min, respectively, which was followed by C. reticulata (peels) for 60, 90 and 120 min, M. longifolia for 45, 60 and 90 min, and C. reticulata (leaves) for 30, 45 and 75 min. Notably, the EO of P. atriplicifolia tested at the dose of 330 μg/cm2 showed complete protection for 60 min which was similar to the commercial mosquito repellent DEET. Gas chromatographic-mass spectrometric analyses of the EOs revealed camphor (19.7%), limonene (92.7%), sabinene (24.9%), carvone (82.6%), and trans-ascaridole (38.8%) as the major constituents of P. atriplicifolia, C. reticulata (peels), C. reticulata (leaves), M. longifolia, and D. ambrosioides, respectively. The results of the present study could help develop plant-based commercial repellents to protect humans from dengue mosquitoes.
... The content of dichloromethane-methanol and 4aα,7α,7aβ-nepetalactone isolated from N. parnassica showed very high mosquito repellency for at least 2 hours against both types of mosquitoes. This study demonstrated the potential use of essential oil extracts, especially dichloromethane-methanol and 4aα,7α,7aβ-nepetalactone N. parnassica, as control agents for A. cretinus and C. pipiens (Gkinis et al., 2014). ...
... A key intermediate in the generation of most iridoids is nepetalactol 3, which, along with its oxidized product, nepetalactone 4, is well-known for its behavioral effect on cats 9,10 . In addition, the nepetalactone isomers are known to have stereodivergent effects in repelling insects [11][12][13][14] . It is therefore desirable to unlock this structural diversity in order to apply it to this and many other potential applications downstream of 3. ...
Thousands of natural products are derived from the fused cyclopentane-pyran molecular scaffold nepetalactol. These natural products are used in an enormous range of applications that span the agricultural and medical industries. For example, nepetalactone, the oxidized derivative of nepetalactol, is known for its cat attractant properties as well as potential as an insect repellent. Most of these naturally occurring nepetalactol-derived compounds arise from only two out of the eight possible stereoisomers, 7S-cis-trans and 7R-cis-cis nepetalactols. Here we use a combination of naturally occurring and engineered enzymes to produce seven of the eight possible nepetalactol or nepetalactone stereoisomers. These enzymes open the possibilities for biocatalytic production of a broader range of iridoids, providing a versatile system for the diversification of this important natural product scaffold.
... However, synthetic analogues could be developed that are more actively repellent. It was also observed that nepetalactone and other terpenoids from catnip are better repellent against anopheles' mosquitos that causes malaria, and against several ticks and mites that cause diseases in livestock and poultry [14][15][16]. Efforts are ongoing to control the spread of malaria by searching for novel antimalarial agents from plants and designing new derivatives of artemisinin and tetraoxane-based compounds [17,18]. However, developing mosquito repellents also needs more attention as they can be used for prevention [19]. ...
Nepetalactones belongs to the group of iridoid monoterpenoids, which are present in the aerial parts of nepeta plants. Nepetalactone is an attractant to feline animals causing euphoric effects, while it is a repellent to mosquitoes and cockroaches. It is also a pheromone for several insect aphid species. The main objective of this research was to study the electronic and spectral properties of nepetalactones. We investigated its structural properties using hybrid density-functional theory of B3LYP and WB97XD functional with the 6-311++G(d,p) basis set to optimize the geometry, and then computed the electronic structure, HOMO–LUMO, natural bond orbitals, molecular electronic potential and its contour map. We also obtained spectral signatures of NMR, IR and UV–Vis, and compared them with experimental data from the literature. The DFT study provided different electronic and spectral information that will be of value for further research on making new derivatives of nepetalactones for commercial purposes. Nepetalactones have a promising future in the development of novel mosquito repellents for the control of malaria and arboviral diseases.
Aphids cause massive agricultural losses through direct damage or as pathogen vectors. Control often relies on insecticides, which are expensive and not selective. An interesting alternative is to use aphid sex pheromones nepetalactone (NON) and nepetalactol (NOL) to interfere with aphid mating or attract aphid predators. Here, we explore production of these compounds in plants, as their precursors can be derived from mevalonate (MVA) and methylerythritol phosphate (MEP) pathways. By introducing six genes, including a major latex protein‐like (MLPL) enzyme, we engineered a functional nepetalactol biosynthetic pathway into plants. Transient expression of these enzymes in N. benthamiana caused production of nepetalactone, without the need for external supplementation with substrates. Targeting all six enzymes into the chloroplast appeared to result in higher NON yields than just chloroplast‐targeting the first two enzymes. We could not detect NOL, suggesting it is rapidly oxidised to NON. In addition, we produced NON in stably transformed Camelina sativa (Camelina) lines. Interestingly, the specific NON enantiomer was different in N. benthamiana compared to in Camelina, indicating the value of different platforms for producing specific isoforms. This opens possibilities for using plants as green factories of pheromones for baits or as pheromone dispensers that interfere with insect behaviour.
Domestic cats and other Felidae species show the characteristic response to silver vine plants (matatabi in Japanese). This response comprises licking and chewing the leaves, rubbing their faces and heads against the leaves, and rolling over on the leaves. The behavioral significance of the feline response has remained undetermined for over 300 years. Our recent studies demonstrated that the response is beneficial to chemical defense against pest mosquitoes. Here, we review our recent studies uncovering the potent bioactive compound for the response, the underlying mechanism of the response, and the behavioral functions of both “rubbing and rolling” and “licking and chewing”.
Catnip (Nepeta cataria) and silver vine (Actinidia polygama) produce iridoids with arthropod-repellent effects. Cats rub and roll against these plants, transferring iridoids to their fur that repels mosquitoes. Cats also lick and chew plant leaves during this response, although the benefit of this additional behavior has remained unknown. Here, we show that feline leaf damage substantially increases iridoid emission from both plants while also diversifying iridoids in silver vine. Cats show an equivalent duration of response to the complex cocktail of iridoids in damaged silver vine and to the much higher level of a single iridoid produced by damaged catnip. The more complex iridoid cocktail produced when silver vine is licked and chewed by cats increases mosquito repellency at low concentration. In conclusion, feline leaf damage contributes by releasing more mosquito-repellent iridoids. Feline olfactory and behavioral sensitivity is fine-tuned to plant-specific iridoid production for maximizing the mosquito repellency gained.
Pesticides are represented by natural or chemical substances or mixtures of substances used for preventing, destroying, or controlling any pest (virucides, bactericides, fungicides, algaecides, herbicides, desiccants, insecticides, nematicides, molluscicides, rodenticides, avicides, piscicides). Despite their beneficial effects exhibited by the inhibitory effects against pests harmful for plants and animals, the chemical pesticides could also be toxic for other organisms and pollutants for the environment. Biopesticides, which are naturally occurring or derived materials from living organisms or their metabolites, have instead low negative effects as compared to chemical pesticides. Currently, under the pressing issues of food security and the need for implementation of a more sustainable agricultural system globally, there is much interest in the development of new biocontrol agents. The purpose of this chapter was to review the progress made in biopesticides development, focusing on microbial and plant-derived products and in the field of chemical pesticides biodecontamination by using microbial enzymes.
Adams, R. P. 2007. Identification of essential oil components by gas chromatography/ mass spectrometry, 4th Edition. Allured Publ., Carol Stream, IL
Is out of print, but you can obtain a free pdf of it at
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The description of the unknown pupa of Aedes cretinus and a key to the known pupae of the albopictus subgroup, scutellaris group, subgenus Stegomyia, genus Aedes are presented. The three species of subgenus Stegomyia, genus Aedes, which occur in Europe, are characterized.
Mosquitoes and Their Control presents a wealth of information on the bionomics, systematics, ecology, research techniques and control of both nuisance and disease vector mosquitoes in an easily readable style, providing practical guidelines and important information for professionals and laymen alike. Ninety-two European species and more than 100 globally important vector and nuisance species are included in the book. Most of them, including all European species, are described in the fully illustrated identification keys, followed by a detailed description of the morphology, biology, distribution and medical importance of each species, including over 700 detailed drawings. Mosquitoes and Their Control includes: Systematics and biology medical significance research techniques illustrated identification keys for larval and adult mosquito genera morphology, ecology, and distribution of the species identified in the keys biological, chemical, physical and genetic control of mosquitoes Mosquitoes and Their Control is a valuable tool for vector ecologists, entomologists, and all those involved with mosquito control, biology, ecology, and systematics world-wide. It will especially benefit those professionals, scientists and students dealing with mosquitoes and their control on a day-to-day basis. Society as a whole stands to gain from improved, environmentally responsible mosquito management programs designed on the basis of a broader understanding of mosquitoes and their control, as provided in this enlightening book. © Springer-Verlag Berlin Heidelberg 2003, 2010. All rights reserved.
Aedes (Stegomyia) albopictus, an invasive mosquito species of great medical importance, was first recorded in Athens, Greece, in 2008. Its presence raised awareness among people and as a consequence numerous "tiger-like" mosquito specimens were sent to Benaki Phytopathological Institute for identification and relevant information. The results of the adult mosquito specimens, collected for three years (2009-2011), revealed that Aedes albopictus occurs in many municipalities around Athens, in Attica Prefecture, and in many parts of the country. The mosquito samples confirmed also the presence of the native species Aedes (Stegomyia) cretinus. Our data, based on people awareness and annoyance, suggest the need to implement appropriate surveillance programs for monitoring the presence and population densities of Stegomyia mosquitoes in the frame of an integrated mosquito control program.