Abstract
Background:
Despite the benefits that synthetic pesticides have provided in terms of pest and disease control, they cause serious long-term consequences for both the environment and living organisms. Interest in eco-friendly products has subsequently increased in recent years.
Methods:
This article briefly analyzes the available ethnobotanical evidence regarding the use of Cannabis sativa as a pesticide and offers a systematic review of experimental studies.
Results:
Our findings indicate that both ethnobotanical and experimental procedures support the use of C. sativa as a pesticide, as remarkable toxicity has been observed against pest organisms. The results included in the systematic review of experimental studies (n=30) show a high degree of heterogeneity, but certain conclusions can be extracted to guide further research. For instance, promising pesticide properties were reported for most of the groups of species tested, especially Arachnida and Insecta; the efficacy of C. sativa as a pesticide can be derived from a wide variety of compounds that it contains and possible synergistic effects; it is crucial to standardize the phytochemical profile of C. sativa plants used as well as to obtain easily reproducible results; appropriate extraction methods should be explored; and upper inflorescences of the plant may be preferred for the production of the essential oil, but further studies should explore better other parts of the plant.
Conclusion:
In the coming years, as new findings are produced, the promising potential of C. sativa as a pesticide will be elucidated, and reviews such as the present one constitute useful basic tools to make these processes easier.
Introduction
Synthetic pesticides have been largely used for crop protection for decades. Although the global diversity outlook published by the Convention on Biological Diversity in 2020 stated that the use of chemical fertilizers and pesticides has stabilized globally, 1 the presence of pesticides in agriculture has increased by almost 1% per year over the past decade, 2 so their use is still remarkably high. Chemical pesticides tend to have concerning negative impacts on the environment at large and local biodiversity. For instance, a major study conducted in eight European countries reported that the use of pesticides was responsible for reduced diversity in terms of plants, insects, and birds. 3 Later studies systematically confirmed this association.4,5 In addition to harms to the environment, human health is also affected by the widespread use of pesticides. 6 Apart from safety concerns related to both the environment and human life, there are limitations in terms of efficacy, because it has been observed that many pathogens develop resistance to chemical pesticides over the long term.7–9
In light of the stated above, and especially considering the concept of “one health,” which emphasizes the interconnection between people, animals, plants, and their environment, 10 interest in eco-friendly or green alternatives for pest control has increased exponentially during recent years. 11 Specifically, products derived from plants and other natural products, commonly termed “biopesticides,” have received special attention. Nicotinoids from Nicotiana tabacum L., pyrethrins from Tanacetum cinerariifolium (Trevir.) Sch.Bip., and secondary metabolites of Azadirachta indica A.Juss. are among the products that have generated significant interest. 12
Besides being barely toxic to humans and vertebrates in general, Benelli et al. highlighted four main benefits associated with botanical pesticides: (i) they are relatively inexpensive and easy to use; (ii) some of them are effective at very low doses; (iii) aqueous botanical extracts can be easily used to treat mosquito breeding sites, without the further addition of other synthetic surfactants; and (iv) these products exert their action through multiple mechanisms, which prevents the development of resistance by pathogens. 13 However, there are also some drawbacks and limitations that restrict their research and use.
First, most of these products consist of the essential oil (EO) of the plant of interest. The composition of the EOs is commonly subjected to variations, and the vegetal material needed for large-scale production could be enormous if the plant does not produce high amounts of EO. Furthermore, certain EOs have shown toxicity for nontarget organisms, such as the EO of Melaleuca alternifolia (Maiden and Betche) Cheel. 14 Thus, despite green alternatives seeming preferable to chemical pesticides, they require technological innovations in order for appropriate formulations and delivery methods to be developed, as well as the cautious selection of the best botanical candidates, and subsequent safety studies regarding nontarget organisms, including humans.
In recent years, Cannabis sativa L. has been proposed as an interesting candidate for use as a pesticide.15,16 It should be noted that while there is only one recognized species—C. sativa—many different taxonomical divisions of the genus (at the species, subspecies, and varieties level) have been proposed.17–22 At present, the most widely accepted hypothesis is that the genus consists of a single species, C. sativa, with several subspecies, varieties, cultivars, and chemovars. Plants that contain <0.3% of Δ 9 -tetrahydrocannabinol (THC) and grown for fiber and seed production are normally called hemp. Cannabis/medicinal cannabis refers to plants that contain higher amounts of THC, which are used primarily for medicinal uses. 23
Apart from the two well-known cannabinoids, THC and cannabidiol (CBD), the plant produces >500 compounds, including other cannabinoids (e.g., cannabichromene, cannabigerol), terpenoids (e.g., myrcene, limonene, trans-caryophyllene), and flavonoids (e.g., apigenin, luteolin, quercetin), among others. 24 However, the chemical profiles are not constant and can differ significantly between different C. sativa landraces and cultivars.25–27 This variation can be caused by differences in genetics, 28 growing conditions,29,30 collection period, 27 and plant parts used. 31 Variability in chemical composition of material used in experiments makes it very difficult to compare the results. To avoid variability, use of recognized cultivars/chemovars, controlled growing conditions, and standardization of the compounds and their proportions, are needed. 32
The compounds and mechanisms through which C. sativa exerts its pesticide effects are not currently elucidated. However, the pharmacological action of terpenes and cannabinoids, as well as interactions between certain compounds, could be involved. 33 Cannabis sativa has a high content of EO; therefore, its cultivation and extraction is economically feasible. The EO is mainly produced in the glandular trichomes of the aerial parts, as part of the viscous and sticky mixture that traps and/or repels insects. As a consequence, C. sativa shows a particular resistance of pests, which allows for eco-friendly cultivation. 15
It should be noted that the use of C. sativa as a pesticide is quite old, as a 1950 report 34 from the United Nations cited a reference from Chemiker Zeitung (a German scientific journal) published in 1922, reporting the use of preparations with a basis of C. sativa leaves as insecticides. According to that reference, the leaves and stalks were dried at a low temperature and the desiccated product reduced to a fine powder. The powder obtained, when spread on pieces of material, woolen cloths, or sprayed over plants, was said to protect them from insects. 34 From historical, non-Western records, we can mention the Arabic Kitāb al-Ḥāwī fī l-ṭibb (The Comprehensive Book of Medicine, 10th century), in which it is recommended to place branches of hemp on the bed to avoid bedbugs and mosquitoes. 35 Similarly, in the Byzantine Empire, Casiano Baso, in his Geoponica, stated that sleeping next to a flexible branch of hemp would repel mosquitoes. 35
The crucial role that the traditional knowledge plays in the discovery of natural products and their uses is well known. In the specific case of C. sativa, the Botanical Institute of Barcelona (IBB; https://www.ibb.csic.es/en) and the University of Barcelona (UB; https://www.ub.edu/portal/web/dp-bsma/botanica) have recently developed a database (CANNUSE; https://cannusedb.csic.es) collecting the global ethnobotanical uses of C. sativa, among which pesticide uses are also reported. 36 Given the evidence coming from traditional knowledge, and the recent interest by many researchers in the potential use of C. sativa as an eco-friendly alternative to current pesticides, further research in this field is considered valuable and necessary.
The present work aims, first, to summarize the traditional ecological knowledge regarding the use of C. sativa as a pesticide, from the references found in the CANNUSE database, and, second, to perform a systematic review of experimental studies assessing the pesticide potential of this plant.
Methods
Before carrying out the literature search, a detailed review protocol was created, which is available from the authors upon request. The systematic review performed in this article was not registered at inception.
Search in CANNUSE database and systematic review of experimental studies
Records related to the use of C. sativa as a pesticide were hand-searched in the CANNUSE database, and the whole document was stored for data extraction. The review of experimental studies was carried out in accordance with the preferred reporting items for systematic reviews and meta-analysis guidelines (PRISMA). 37 We attempted to identify all experimental studies available to review in which C. sativa or isolated cannabinoids were assessed against pests, from 1970 to March 2021. Electronic searches were performed using PubMed, Web of Science, Google Scholar, and CAB Direct databases. The following keywords were used: (cannabis OR hemp) AND (pest* OR insect* OR plague). References were retrieved through searching electronic databases and manual searches through the reference lists of identified literature.
Eligibility criteria
The following inclusion and exclusion criteria were established before the literature search: (i) Article type. All studies published in peer-reviewed journals involving the use of any chemovar or cultivar of C. sativa or isolated cannabinoids against pests were included. Pests are understood in a broad sense. Mosquitoes, flies, ticks, mites, worms, aphids, bugs, thrips, snails, or beetles, among others, that are considered pests for crops were included. Reviews, abstracts, comments, and editorials were excluded. (ii) Study design. The review included bioassays using C. sativa extracts or isolated cannabinoids against pests. (iii) Experiments. All designs evaluating the potential pesticide use of C. sativa or cannabinoids were included. (iv) Outcomes. We included all reports that assessed the biological effects of C. sativa extracts or cannabinoids systematically (with standardized biological measures).
Data extraction
One author (G.O.) screened all studies, and doubts were resolved by a team of botanical experts. From the articles included, we recorded the names of authors, year of publication, study design, type of experiment, chemovar of C. sativa used, parts of the plant used, method of extraction, pest organisms used, results of phytochemical analysis (if any), and main findings observed (mainly through parameters like LC50 and LC90, but also through other measures, depending on the study). Pest organisms were further classified in taxonomic groups and combined with the main findings in Table 2.
Results and Discussion
This investigation comprised an initial selection of references included in the CANNUSE database reporting on traditional ecological knowledge regarding the use of C. sativa as a pesticide. Then, a systematic review of available experimental evidence possibly supporting such use was performed. Studies assessing the potential activity of C. sativa extracts were collected and summarized. They mostly consisted of bioassays using various chemovars or cultivars of C. sativa against distinct species. While synthesizing the extant literature, we have bridged traditional and experimental knowledge, providing a fruitful basis that may help to develop a more sustainable and eco-friendly agriculture practice.
First, it should be noted that, from a broader perspective, the problem of pests in large-scale agriculture is primarily caused by unsustainable models prioritizing monocultures. This kind of agricultural practice is associated with biodiversity loss and, therefore, enhanced vulnerability to outbreaks of virulent pest insects.38,39 Thus, the use of C. sativa or other products for pest control should be conceived of as partial solution that must be accompanied by other strategies capable of addressing the underlying causes of the problem. In that regard, however, insect pests have always existed, and the use of EOs or crushed plant parts against insects has been extensively reported on as being successful in traditional medicines.40,41 Nevertheless, the use of C. sativa for that indication has not received much attention, possibly because of its several other uses (medicinal, as a textile or alternative material, among others) have received more interest.
Traditional ecological knowledge
Nine references42–50 were found in the CANNUSE database (Table 1). It should be noted that other, historical references exist as well, such as the ones cited previously.34,35 This suggests a long tradition of C. sativa use as a pesticide. Regarding these specific references, they were reported from India,43,44,46,49,50 Pakistan,29,35,42,48 Nepal, 45 and one from Africa (Uganda). 47
CANNUSE database references informing about the ethnobotanical evidence of the potential use of Cannabis sativa as a pesticide
NS, not specified.
Scarce but interesting information can be drawn from these traditional ecological reports. The leaves are the part of the plant that was mostly used (in eight of nine references),42–47,49,50 but the use of the whole plant is also mentioned in three references.43,44,49 Leaves can be pressed to obtain “juice” 42 or for the preparation of extracts. 47 Among the methods used to administer C. sativa, smoke is mentioned in three references,43,46,47 whereas fresh or dried leaves were also reportedly used in granaries or under the bed for repelling insects.45,50
Unfortunately, ethnobotanical studies rarely include information on chemical composition of the studied plants. It has already been proven that the chemical profile of plants can change depending on various factors, such as genetics and growing conditions. As many of the studies analyzed here come from a determined geographic region (Southwest Asia), they could present different chemical profiles compared with C. sativa plants located in other geographical regions. 51 Caution is therefore needed when interpreting the results.
Systematic review of experimental studies
The search of the literature yielded 595 references that were reviewed for abstract screening. Hand searching the bibliographies of the selected citations identified 10 additional citations. Following this and after the removal of duplicates, 41 potentially relevant references were identified. Full-text reports for these citations were obtained for a detailed evaluation. Eleven citations were excluded for various reasons (Fig. 1). Thus, 30 citations12,15,52–79 were included in the systematic review. The main characteristics and results of each citation are given in Table 2.
Experimental studies assessing the potential of Cannabis sativa as a pesticide
AEX, aqueous extract; AP, aerial parts; ASO, aqueous solution; CBD, cannabidiol; CEX, chloroform extraction; CI, confidence interval; CS, carmagnola selezionata; CT, carbon tetrachloride; DEC, decoction; DEET, N,N-diethyl-meta-toluamide; DMSO, dimethyl sulfoxide; E, effective; EEX, ethanol extraction; EO, essential oil; EO+, essential oil and isolated compounds; HD, hydrodistillation; HEX, hexane extraction; IN, Ineffective; INF, inflorescences; L, leaves; LC, lethal concentration; LD, lethal dose; LEX, leaf extract; M, maceration; MEX, methanol extraction; PE, petroleum ether; PL, pulverized leaves; RT, roots; S, seeds; STD, steam distillation; THC, Δ 9 -tetrahydrocannabinol; TS, thin stems.

Flow diagram of the selection of studies for the systematic review.
The various organisms used in the experimental studies were classified into phylum, class, and order. Most of them (20 of 30) focused on the effect of C. sativa on arthropod pests. These results are in accordance with the data obtained from traditional ecological knowledge, where six of nine studies specifically mentioned the use of C. sativa as an insect repellent. The studies included in the systematic review found remarkable toxicity of C. sativa extracts against all the Arachnida using mostly aerial parts and inflorescences.12,56,65,69
In the Insecta group, C. sativa toxicity was reported against Oryzaephilus surinamensis, 61 Tribolium confusum, 61 Aedes aegypti, 70 Aedes albopictus, 53 Anopheles gambiae, 67 Anopheles stephensi, 67 Musca domestica,15,54 Aulacorthum solani, 56 Brevicoryne brassicae, 52 Myzus persicae, 54 Schizaphis graminum, 12 Manduca sexta, 66 Plodia interpunctella, 61 Spodoptera littoralis,15,54 Culex quinquefasciatus,15,63 Sitophilus oryzae, 77 and Callosobruchus chinensis,77,79 although one study found the C. sativa extract to be ineffective against C. quinquefasciatus. 54 Other species in which C. sativa extracts did not show relevant toxicities included Reticulitermes virginicus, 68 Brassicogethes aeneus, 72 Trogoderma granarium, 57 Chaoborus plumicornis, 68 Drosophila melanogaster, 68 and Frankliniella occidentalis. 12
It is not possible to elucidate the reasons for this differing efficacy, because wild C. sativa and other chemovars/cultivars, different parts of the plant, and different extraction methods were found to be efficacious in some cases and inefficacious in others. The results for the Chromadorea species were also mixed. Different cultivars and chemovars (“Tiborszallasi,” “Futura 75,” MX-CBD-11, MX-CBD-707) showed toxicity against Heterorhabditis bacteriophora, Steinernema carpocapsae, and Steinernema feltiae. 60 Meloidogyne incognita also was affected by C. sativa in five different studies, three of them using wild C. sativa plants and the others nonspecified chemovars.58,62,64,68,74
In another study, an extract of wild C. sativa affected the success of egg hatching of M. incognita. 75 However, no toxicity was observed in three species (Caenorhabditis elegans, Strongyloides papillosus, and Haemonchus contortus).55,68 These three Nematoda species were tested in studies using wild C. sativa. The only study performed on species from Gastropoda (Physella acuta) reported toxicity of the EO extracted from aerial parts. 53 C. sativa EOs were effective against the two species of fungi tested (Sclerotium rolfsii and Cryptococcus neoformans).59,71
More than half of the studies (17 of 30) reviewed used wild C. sativa plants. Wild C. sativa is certainly the most suitable plant type to corroborate the ethnobotanical evidence, as no cultivar or chemovar is usually reported in traditional ecological reports. However, in terms of the reliability and replicability of the results, specific cultivars/chemovars of C. sativa would be preferable. Moreover, it should also be noted that wild plants would present varying chemical profiles depending on region, soil type, harvesting method, storage conditions, and many other factors. Thus, even when using wild C. sativa in accordance with ethnobotanical evidence, a remarkable degree of variability should be assumed. This issue has been problematic not only in the field of C. sativa research80,81 but also in research with natural products in general. 82 Metabolic profiling and other validated methods should be performed in studies using complex natural products, although many other approaches are being implemented, such as the use of standardized extracts.
Other sources of heterogeneity include the parts of the plant used and the extraction method. Regarding the former, 14 studies52,58,59,63,64,68,73–79 used leaves, whereas five studies54,57,67,69,71 used inflorescences. The remaining studies used combinations of leaves, inflorescences, and other parts of the plant. It should be noted that, generally, the EO is primarily secreted by glandular trichomes present on the surface of plant organs, particularly flowers and leaves. However, in the specific case of C. sativa, a greater amount of EO is produced on the inflorescences. 54 Moreover, it has been described that the upper inflorescences have significantly higher amounts of cannabinoids and terpenoids than those lower down the stem. 83 Therefore, the plant parts selected would cause significant variations in the extracted products.
Regarding extraction methods, steam distillation and hydrodistillation were the most commonly reported. In that regard, two major approaches can be outlined from the literature on C. sativa research. On one side, conventional methods, such as organic solvent extraction, have been extensively used. This process exposes the plant constituents to the combined effects of heat and acid, which may undergo relevant modifications. On the other side, innovative, still marginal methods can be observed, such as superficial fluid extraction. Carbon dioxide, which is quite inefficient at dissolving polar compounds, is usually used as the supercritical solvent. To improve the solubility of polar substances, a cosolvent or modifier is often added. 84 To avoid heterogeneity and chemical modifications of EO composition derived from conventional extraction method, future studies should preferentially use improved extraction methods.
Of interest, one study 15 found greater efficacy in an EO extracted from inflorescences than in the EO extracted from leaves. Moreover, its efficacy was better than those of other EOs considered to be highly promising, such as the ones obtained from Cunninghamia konishii Hayata or Corymbia citriodora Hook. 15 Another study found that the EOs of three different chemovars of C. sativa were more effective when they were extracted from fresh parts rather than dried. 71 Considering the well-known loss of terpenes in the drying process, including the more volatile monoterpenes especially, 85 this suggests that terpenes are greatly involved in the pesticide properties of C. sativa. In the same study, 71 N,N-diethyl-meta-toluamide was used as a positive control, and it was found that C. sativa extracts had an equivalent efficacy. Another study used chlorpyrifos as a positive control, finding it more efficacious than C. sativa extract. 76 Future studies should also use positive controls to compare efficacy.
Although it is generally claimed that natural, so-called green products are safer for the environment than synthetic ones, few studies have assessed the safety of plant EOs in nontarget organisms, including humans.86,87 Among the studies reviewed, two studies assessed the potential toxicity of C. sativa against three nontarget species. They reported the absence of toxicity for two of them (Harmonia axyridis and Eisenia fetida) and toxicity against Cloeon dipterum, although the toxicity was lower than for target species.
Further studies need to test C. sativa toxicity against more nontarget species of interest. Finally, other related, potentially fruitful uses with regard to crop protection were not included in the review, but they deserve to be mentioned. First, it seems that the inclusion of C. sativa in composting material could entail certain benefits 88 and requires further research, because the enrichment of composting materials is currently under investigation. 89 In addition, a study that used CBD oil as a postharvest approach in strawberries is also highly interesting. 90 Despite the scarcity of studies for that indication, we suggest that, given the global and economic interest in postharvest management, these early, promising results should be taken into account. 91
Mechanisms of C. sativa pesticide activity
At this point, we can briefly suggest some mechanisms of action through which C. sativa may exert its pesticide effects. Studies describing the mechanisms of action of cannabinoids with regard to their insecticidal activity are lacking, but their nematocidal,60,64,74,75,78 acaricidal, 65 and larvicidal 61 effects have been reported even in the absence of cannabinoid receptors in insects, 92 which suggests other mechanisms unrelated to those receptors. First, it should be noted that, at least in vitro, C. sativa exerts a powerful inhibition of acetylcholinesterase (AChE), which is the main effect of insecticides like organophosphates, neonicotinoids, and spinosyns, which eventually cause cholinergic poisoning. 93 In C. sativa, both AChE and butyrylcholinesterase inhibition seems to be exerted in parallel by different compounds, such as beta-sitoserol, campesterol, apigenin, α-bisabolene, Δ 8 -tetrahydrocannabinol, THC and other cannabinoids, kaempferol, luteolin, stigmasterol, quercetin, α-guaiene, α-humulene, and caryophyllene oxide. 94
In addition, both THC and CBD are P-glycoprotein (P-gp) inhibitors. 95 P-gp belongs to an ATP-binding cassette (ABC) transporter subfamily, responsible for the drug efflux from the cytoplasm to the outside of the cell. 96 It is also the main mechanism that has been associated with insecticide-resistant phenotypes. 97 To sum up, it is highly plausible that, along with other mechanisms (e.g., point mutations), insects use ABC transporters for the excretion of plant secondary metabolites or chemical pesticides97–100 and, therefore, for the development of drug resistance. Then, with P-gp inhibition, not only would higher bioavailability of other insecticidal compounds of C. sativa be achieved, but also reduced probability of the development of drug resistance.
Unfortunately, 15 studies included in this review12,55,56,58,59,62–65,70,74–79 did not perform phytochemical analyses, adding a notable degree of uncertainty that should be avoided in future research. The most commonly reported compounds in the studies reviewed that performed phytochemical analyses15,52–54,56,57,60,67–70,72,73 were terpenoids [(E)-caryophyllene, trans-caryophyllene, myrcene, α-humulene, and α-pinene]. These volatile compounds are well known for their diverse biological activities against insects, because they can act as insecticides, 101 antifeedants, 102 or repellents, 103 among many other functions.
The mechanism of action involved in pesticide effects involves AChE inhibition as well as the blocking of 3 H-octopamine or GABA receptors. 104 Of note, certain terpenoids tend to be species specific105,106 and, thus, some of them affect only certain insects. The fact that C. sativa contains a high number of terpenes is an advantage in that sense. 107 C. sativa is also rich in flavonoids, which are involved in several functions mostly related to the plant–environment interaction. They tend to affect the behavior and growth of insects through the inhibition of AChE, the ecdysone receptor, or alterations in the gustatory, sensile, and neuronal responses to food. 108 Remarkably, they are known to also be P-gp inhibitors 109 and, additionally, glutathione S-transferases (GSTs) inhibitors. 110 GSTs are involved in the detoxifying process of insecticides, so one of the putative roles of flavonoids is also to fight against drug resistance mechanisms.
Of note, C. sativa EO inhibits AChE in a more effective manner than other EOs, 111 and its efficacy was greater than other highly promising EOs, such as ones obtained from C. konishii Hayata or C. citriodora Hook. 15 Thus, there must be specific reasons for this enhanced efficacy of C. sativa as compared with other plants. From the information that we gathered in this article, we can only suggest putative mechanisms. First, it is possible that the high concentrations of terpenes and flavonoids provide C. sativa with remarkable pesticide properties.
Although this level of chemical richness is quite ubiquitous in the plant kingdom, other plants have been known to present these levels of secondary metabolites. It is also probable that the cannabinoids found in the plant are enhancing, both directly and indirectly, the pesticide properties of the whole EO. Despite the synergistic effects that have been described in the clinical use of C. sativa,112–114 they cannot be extrapolated to other organisms and biological environments. However, interaction effects among compounds present in natural products are common, 115 and could in this case be related with P-gp inhibition mentioned previously. This could lead to complex synergistic or additive effects, but further research should elucidate specific mechanisms.
In light of the findings reported in the studies reviewed and from a classic pharmacological perspective, using isolated compounds from the EO, yielded higher efficacy in the two former studies.55,56 Although the isolated compounds exerted enhanced effects in these assays, the use of the whole EO should not be discounted; first, because of the potential development of drug resistance over the long term, as observed with chemical pesticides,9,116 and second, because of the evidence from the polypharmacology paradigm.
Mostly developed in the field of human pharmacology, but with obvious connections to phytochemistry and phytotherapy, this paradigm offers a strong body of evidence supporting the use of complex drug products that modulate several targets rather than highly selective ligands.117–119 One of the main points that justifies this complex approach is that living organisms are complex systems organized within complex networks that, most often, are capable of resisting selective “attacks” through compensatory mechanisms, and thus the modulation of numerous targets is advantageous. In the specific case of pesticides, the argument of the absence of drug resistance in the case of complex products could be more compelling. For instance, the multiple mechanisms described above make the development of resistance extremely unlikely. Moreover, among the hundreds of compounds of different classes within the EO, there are clear interaction effects (additive or synergistic, but potential antagonistic effects should also be identified) that can improve the efficacy of the product.120–123 To obtain these benefits and a suitable product, we would recommend the use of the whole C. sativa EO involving appropriate extraction methods and the proper plant varieties and plant parts, which are factors that modify EO composition.
Of note, in light of the results observed in this review, it seems that most of the experimental studies support the traditional use of C. sativa as a pesticide, because varying rates of toxicity against different pest organisms have been systematically reported, although sometimes with a certain degree of heterogeneity. There has been a previous narrative review published offering valuable insight and a comprehensive overview of the evidence from distinct perspectives. 16 However, to the best of our knowledge, this is the first systematic review assessing the effectiveness of C. sativa as pesticide. 16
We hope the information provided here will contribute to other researchers designing further research. The main limitation of this review is the restricted number of studies that have addressed the pesticide potential of C. sativa. We also found a high heterogeneity of methods used in the studies reviewed and limited knowledge regarding the phytochemical profile of samples used. The ethnobotanical evidence was obtained from one database (CANNUSE), and four other databases (PubMed, Web of Science, Google Scholar, and CAB Direct) were used to search for experimental studies. It is possible that other studies, either ethnobotanical or experimental, remained out of scope and might be found in other databases. Owing to the Boolean string used for search, the results of our findings might be biased toward phylum Arthropoda, particularly class Insecta. Despite this, we consider the review presents and organizes relevant information that can be fruitful for future lines of research.
Conclusion
The potential use of C. sativa as a pesticide has been highlighted in this systematic review. Despite the high degree of heterogeneity observed in the reviewed studies, excellent results have been observed and certain general recommendations can be extracted. Cannabis sativa EO could be a suitable candidate as a greener alternative to current pesticides, because of its eco-friendly cultivation, its numerous end-products that can be obtained beyond the EO (fiber, food, etc.), its interesting mechanisms of action, and the renewed interest and recent regulations allowing for and facilitating its large-scale cultivation.
Footnotes
Acknowledgments
The authors thank CIJA Preservation S.L. for their support in the project, Gerard Talavera and Jan Simic for their support in the classification of animal species reported in this article, and Dr. M.T. Colomina for reviewing the final version of the article. The authors also thank Dr. J.M. McPartland and an anonymous reviewer for the revision of this article. All authors approved and agreed this publication.
Authors' Contributions
G.O., M.B., J.C.B., A.G., D.V., and T.G. conceived the research. G.O. performed the data search and wrote the first draft of the article. M.B., A.G., D.V., and T.G. resolved conflicts in the systematic review search. M.B., A.G., D.V., and T.G. prepared the final version of the article. J.C.B. provided counseling. T.G. and J.C.B. supervised the whole process. All authors approved the final version of the article.
Data Availability Statement
Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.
Author Disclosure Statement
No competing financial interests exist.
Funding Information
This study was part of the PhD project of GO, for which he received the Industrial Doctorate public grant by AGAUR-GENCAT. This work was supported by: project WECANN from the Spanish government [Grant No. CGL2017-84297-R, AEI/FEDER, UE], from the Generalitat de Catalunya [Grant No. 2017SGR1116], from the Institut d'Estudis Catalans [Grant No. PRO2021-S02-VALLES], and an FPI predoctoral contract of the Ministerio de Ciencia, Innovación y Universidades [Grant No. PRE2018-083226].
