ArticleLiterature Review

Essential Oils as Ecofriendly Biopesticides? Challenges and Constraints

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Abstract

Recently, a growing number of plant essential oils (EOs) have been tested against a wide range of arthropod pests with promising results. EOs showed high effectiveness, multiple mechanisms of action, low toxicity on non-target vertebrates and potential for the use of byproducts as reducing and stabilizing agents for the synthesis of nanopesticides. However, the number of commercial biopesticides based on EOs remains low. We analyze the main strengths and weaknesses arising from the use of EO-based biopesticides. Key challenges for future research include: (i) development of efficient stabilization processes (e.g., microencapsulation); (ii) simplification of the complex and costly biopesticide authorization requirements; and (iii) optimization of plant growing conditions and extraction processes leading to EOs of homogeneous chemical composition.

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... Our historical knowledge of plant extracts being used as pesticides is fragmented. We do know that in Europe people relied on this practice over 3000 years ago to fight ectoparasites and to protect stored foods (Pavela 2016). Chrysanthemum flowers and aromatic plants were the main sources of such extracts. ...
... Essential oils are considered a very promising option for the development and production of botanical biopesticides (Isman 2000;Tripathi et al. 2009;Isman et al. 2011;Regnault-Roger et al. 2012;Pavela and Benelli 2016). They are produced using an extraction method set out in the AFNOR T-75-006 standard, which specifies how they must be obtained via steam distillation, dry distillation or mechanical processes. ...
... All these arguments explain why essential oil-based biopesticides are exempt from regulation by the United States Environmental Protection Agency. Several botanical insecticides using essential oils (rosemary, mint, cinnamon, thyme, black pepper, clove) are available on the North American market and have uses ranging from farming to stored food protection, park management and disease vector control (Cloyd et al. 2009;Isman et al. 2011;Pavela 2016). Sweet orange essential oil is sold commercially around the world as an insecticide, especially against whiteflies, and as a fungicide, mainly against powdery mildew (Table 13.1). ...
... Most recent statistics holds that 75% of biopesticides used consist of Bt-based products (Samada et al. 2020). Neem has proven to be the most widely used botanical biopesticide (Rodgers 1993;Leng et al. 2011;Pavela 2014;George et al. 2014;Pavela and Benelli 2016;Huang et al. 2020). Moreover, neem has demonstrated multiple modes of action by acting as an antifeedant, sterilant, ovicidal and insecticide. ...
... EOs display a wide range of biopesticidal activities ranging from lethal to sublethal effects against Coleoptera, Diptera, Hemiptera Isoptera and Lepidoptera (Regnault-Roger et al. 2012;Pavela and Benelli 2016;Campos et al. 2019). Table 6.1 shows the pesticidal properties of some EOs from various plants. ...
Chapter
The growing concern over potential hazards from chemical pesticide safety among consumers and potential harm to the environment has culminated in consideration of natural management strategies of pests. Because they are complementary to most crop production systems, biopesticides based on plants can be integrated into pest management systems. Plant essential oils (EOs) can replace the more persistent non-natural pesticides in protecting the environment from the accumulation of chemicals reduce resistance and increase crop productivity. In addition, they possess low mammalian toxicity, broad-spectrum activity, and degrade rapidly in foodstuffs. In addition to exhibiting distinctive properties compared with synthetic pesticides, including high levels of pest toxicity and reduced toxicity toward non-target organisms, EOs possess contact, feeding deterrence, fumigant toxicity, oviposition, and repellent properties. In this chapter, we review the sources of EOs, their insecticidal activities, constituents, and mode of action and discuss their synergism and formulation with encapsulation for producing nanoinsecticidal products.
... Most recent statistics holds that 75% of biopesticides used consist of Bt-based products (Samada et al. 2020). Neem has proven to be the most widely used botanical biopesticide (Rodgers 1993;Leng et al. 2011;Pavela 2014;George et al. 2014;Pavela and Benelli 2016;Huang et al. 2020). Moreover, neem has demonstrated multiple modes of action by acting as an antifeedant, sterilant, ovicidal and insecticide. ...
... EOs display a wide range of biopesticidal activities ranging from lethal to sublethal effects against Coleoptera, Diptera, Hemiptera Isoptera and Lepidoptera (Regnault-Roger et al. 2012;Pavela and Benelli 2016;Campos et al. 2019). Table 6.1 shows the pesticidal properties of some EOs from various plants. ...
Chapter
Modern agricultural production is dominated by the use of synthetic chemical pesticides, which account for 95% of the global market share of total pesticide use. However, this over-reliance on synthetic pesticides adversely affects and interferes with the functioning of the ecosystem. Neem (Azadirachta indica), a botanical biopesticide widely known for its bactericidal, fungicidal, insecticidal, herbicidal, and nematicidal properties, offers an eco-friendly alternative to synthetic pesticides. To date, more than 200 bioactive compounds have been extracted from neem, and several commercial formulations have been developed and registered as broad-spectrum biopesticides. More advanced strategies in the use of neem as a botanical biopesticide have been developed with a focus on developing more innovative and effective approaches. This chapter also covers current advancement on neem bioactive ingredients, their efficacy and extraction methods. In addition, stability of the bioactive compounds and environmental, health and safety issues are discussed.
... Additionally, although no significant mortality was observed in the pupal stage, only 12% of the larvae pupated and emerged as adults in the case of the NE from B. persicum. As previously found, EOs can significantly reduce the vitality and fertility of the subsequent insect generation (Pavela and Benelli, 2016). However, only very little information is available for NEs. ...
... works, the authors found the relative selectivity of EOs to non-target organisms. Therefore, EOs are generally considered environmentally friendly and safe natural substances (Pavela and Benelli, 2016). If, of course, they are used with care and in a diluted state. ...
Article
Essential oils (EOs) represent innovative and safe botanical pesticides to be exploited in different fields, including agriculture, being often obtained by cheap and easily available plant crops. However, their use is threatened by some limits, which are mainly linked to their physico-chemical properties. In this regard, the use of nanoemulsions (NEs) usually enables to overcome these limits but often also to improve the biological activities of these products. Bunium persicum (Boiss.) B Fedtsch. and Ziziphora clinopodioides Lam. are two aromatic plants of economic interest well known for their traditional food and medical uses. Their EOs exhibited several biological properties, including a remarkable insecticidal activity against different targets. Here, the chemical analysis of the two EOs revealed the predominance of γ-terpinene (35.8%), cumin aldehyde (16.6%), γ-terpinen-7-al (14.0%), and α-terpinen-7-al (11.7%) for B. persicum, and pulegone (55.6%), piperitenone (12.8%), and iso-menthone (8.0%) for Z. clinopodioides. NEs were successfully obtained by high-pressure homogenization or ultrasonication method, using polysorbate 80 as emulsifier. The EOs and their 10% NEs were evaluated against larvae and pupae of Culex quinquefasciatus Say mosquitoes. In detail, both EOs exhibited a good larvicidal efficacy (LC50 of 35.8 and 68.9 µL L−1 for B. persicum and Z. clinopodioides, respectively). Bunium persicum EO NE showed higher efficacy than the EO alone (LC50 = 290.4 µL L−1), considering that only the 10% of the EO was encapsulated. Conversely, Z. clinopodioides NE showed the same efficacy than the EO alone (LC50 of 759.8 µL L−1). In addition, both NEs displayed significantly better sublethal toxicity compared with the EOs. Moreover, even if no significant mortality was detected in the pupal stage, only 12% of the larvae pupated and emerged as adults in the case of the NE from B. persicum. In conclusion, both EOs and their NEs could be promising candidates for the development of botanical pesticides, also considering the commercial availability and affordability of these EOs.
... Most recent statistics holds that 75% of biopesticides used consist of Bt-based products (Samada et al. 2020). Neem has proven to be the most widely used botanical biopesticide (Rodgers 1993;Leng et al. 2011;Pavela 2014;George et al. 2014;Pavela and Benelli 2016;Huang et al. 2020). Moreover, neem has demonstrated multiple modes of action by acting as an antifeedant, sterilant, ovicidal and insecticide. ...
... EOs display a wide range of biopesticidal activities ranging from lethal to sublethal effects against Coleoptera, Diptera, Hemiptera Isoptera and Lepidoptera (Regnault-Roger et al. 2012;Pavela and Benelli 2016;Campos et al. 2019). Table 6.1 shows the pesticidal properties of some EOs from various plants. ...
Chapter
Entomopathogenic fungi are microorganisms capable of infecting and killing arthropods and therefore have a great potential in pest management. As the extensive use of synthetic pesticides has led to increased resistance in insects, decreased natural enemies, and had negative impacts on environmental and human health, the search for eco-friendly control agents is urgent. Entomopathogenic fungi are promising alternatives in this regard and are attracting global attention, with increasing efforts and financial investments being made for the development, commercialization and use of fungus-based control products. Despite scientific and technological advances, there is still a need for studies to expand the number of species applicable in pest management and improve their performance in the field. There is also a need to increase user awareness regarding their correct use with the aim to establish their widespread adoption and market potential. This chapter covers the main taxonomic groups that comprise entomopathogenic fungi, their modes of action to establish insect infection and spread, and the insect’s defense mechanisms against these fungi. Furthermore, techniques of fungal isolation, selection, and production are discussed. The usage status, challenges, and prospects of mycoinsecticides are also addressed, highlighting their application potential for sustainable agricultural production.
... Most recent statistics holds that 75% of biopesticides used consist of Bt-based products (Samada et al. 2020). Neem has proven to be the most widely used botanical biopesticide (Rodgers 1993;Leng et al. 2011;Pavela 2014;George et al. 2014;Pavela and Benelli 2016;Huang et al. 2020). Moreover, neem has demonstrated multiple modes of action by acting as an antifeedant, sterilant, ovicidal and insecticide. ...
... EOs display a wide range of biopesticidal activities ranging from lethal to sublethal effects against Coleoptera, Diptera, Hemiptera Isoptera and Lepidoptera (Regnault-Roger et al. 2012;Pavela and Benelli 2016;Campos et al. 2019). Table 6.1 shows the pesticidal properties of some EOs from various plants. ...
Chapter
Full-text available
Biopesticides, using living microbial bodies and their bio-active composites against insects, are potential replacements for synthetic insecticides for safer and modern food production systems. Entomopathogenic bacteria (EPB) are important biological control agents of insect pests since the last century. Though bacterial species have been documented to be used against insects for developing symbiotic relationships, only a few of them are identified as entomopathogens. Most of these are members of the family Bacillaceae, Enterobacteriaceae, Pseudomonadaceae, Clostridiaceae, and Neisseriaceae. More than 100 bacterial species have been reported to infect various arthropods. Bacillus thuringiensis (Bt), B. sphaericus, B. cereus, and B. popilliae are the most appreciated microbial pest control agents. However, new bacterial species also need to be explored for their entomopathogenic role and materialized as new biopesticide products. The commercial biopesticides based on novel EPBs with improved genetic materials must be a part of future research for effective integrated pest management programs. This present chapter highlights the classification, infection, replication, transmission mechanisms, and important EPB in integrated pest management.
... Most recent statistics holds that 75% of biopesticides used consist of Bt-based products (Samada et al. 2020). Neem has proven to be the most widely used botanical biopesticide (Rodgers 1993;Leng et al. 2011;Pavela 2014;George et al. 2014;Pavela and Benelli 2016;Huang et al. 2020). Moreover, neem has demonstrated multiple modes of action by acting as an antifeedant, sterilant, ovicidal and insecticide. ...
... EOs display a wide range of biopesticidal activities ranging from lethal to sublethal effects against Coleoptera, Diptera, Hemiptera Isoptera and Lepidoptera (Regnault-Roger et al. 2012;Pavela and Benelli 2016;Campos et al. 2019). Table 6.1 shows the pesticidal properties of some EOs from various plants. ...
Chapter
Full-text available
The successful control of many insect-pests makes entomopathogenic nematodes (EPNs) among one of the best biocontrol agents for insect pests. Moreover, the ability of EPNs to seek out their hosts and kill them in those habitats where chemicals fail makes them even more attractive. The EPNs-bacterial mutualistic association helps them kill their hosts in a relatively shorter period than other necromenic or parasitic nematode associations. In addition to this end-user safety, hotspot application which allows minimizing treated area, natural enemies’ safety, withholding period absence, and environmental protection are a few of many advantages over chemical pesticides. Two important genera of EPNs, i.e., Heterorhabditid and Steinernematids, are associated with symbiotic bacteria Photorhabdus and Xenorhabdus, respectively, while bacterial symbiont of neosteinernamatids is yet to be described. About 21 species of Heterorhabditis and 100 species of Steinernema have been isolated and identified worldwide. With the increasing environmental concerns and low efficacy of synthetic pesticides, agriculturists and researchers have a growing interest in finding alternatives to synthetic pesticides. Several EPNs can be widely used in place of synthetic pesticides in agro-ecosystem. There is still a need to improve several aspects of EPNs, such as efficacy and efficiency, reduced costs, mass production, and formulation technology. Furthermore, their potential for recycling in the host population beckons them to be further exploited for sustainable pest control. This chapter will emphasize the use and potential of EPNs as an integral part of integrated pest management. To aid with understanding the potential of EPNs, this chapter will also provide an overview of ecology and biology, mass production, application strategies, and integration with other management tools.
... EOs are complex mixtures, even of several dozens of compounds; several factors can have a significant impact on their insecticidal efficacy, including their chemical composition [33], mutual synergistic relationships among the EO constituents [34,35], the mechanisms of action of active substances [33], and the mode of application and postapplication conditions [36,37]. Regarding the tested EOs, it can be noted that they were very complex mixtures where the content of none of the major compounds was higher than 50%. ...
... EOs are complex mixtures, even of several dozens of compounds; several factors can have a significant impact on their insecticidal efficacy, including their chemical composition [33], mutual synergistic relationships among the EO constituents [34,35], the mechanisms of action of active substances [33], and the mode of application and postapplication conditions [36,37]. Regarding the tested EOs, it can be noted that they were very complex mixtures where the content of none of the major compounds was higher than 50%. ...
Article
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Patagonia is a geographical area characterized by a wide plant biodiversity. Several native plant species are traditionally used in medicine by the local population and demonstrated to be sources of biologically active compounds. Due to the massive need for green and sustainable pesticides, this study was conducted to evaluate the insecticidal activity of essential oils (EOs) from understudied plants growing in this propitious area. Ciprés (Pilgerodendron uviferum), tepa (Laureliopsis philippiana), canelo (Drimys winteri), and paramela (Adesmia boronioides) EOs were extracted through steam distillation, and their compositions were analyzed through GC–MS analysis. EO contact toxicity against Musca domestica L., Spodoptera littoralis (Boisd.), and Culex quinquefasciatus Say was then evaluated. As a general trend, EOs performed better on housefly males over females. Ciprés EO showed the highest insecticidal efficacy. The LD50(90) values were 68.6 (183.7) and 11.3 (75.1) µg adult−1 on housefly females and males, respectively. All EOs were effective against S. littoralis larvae; LD50 values were 33.2–66.7 µg larva−1, and tepa EO was the most effective in terms of LD90 (i.e., <100 µg larva−1). Canelo, tepa, and paramela EOs were highly effective on C. quinquefasciatus larvae, with LC50 values < 100 µL L−1. Again, tepa EO achieved LD90 < 100 µL L−1. This EO was characterized by safrole (43.1%), linalool (27.9%), and methyl eugenol (6.9%) as major constituents. Overall, Patagonian native plant EOs can represent a valid resource for local stakeholders, to develop effective insecticides for pest and vector management, pending a proper focus on their formulation and nontarget effects.
... Naturally occurring substances, such as essential oils (EOs), have a better track record than synthetic pesticides in terms of human health and environmental safety (Pavela and Benelli 2016, Brügger et al. 2019. EOs are volatile compounds that degrade rapidly in the environment and impose a very low risk of insect pest resistance (Isman andGrieneisen 2014, Pavela andBenelli 2016). ...
... Naturally occurring substances, such as essential oils (EOs), have a better track record than synthetic pesticides in terms of human health and environmental safety (Pavela and Benelli 2016, Brügger et al. 2019. EOs are volatile compounds that degrade rapidly in the environment and impose a very low risk of insect pest resistance (Isman andGrieneisen 2014, Pavela andBenelli 2016). EOs and their components have lethal and sublethal effects on a variety of pests (Isman 2006, Regnault-Roger et al. 2012, Plata-Rueda et al. 2017) but have limited effects on natural enemies, making them a viable option for integrated pest management (IPM) programs. ...
Article
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Methyl benzoate (MBe), a volatile organic molecule, has been shown to have insecticidal effects on a variety of agricultural, stored products, and urban arthropod pests in recent investigations. However, the toxicity of MBe against nontarget organisms has rarely been investigated. This study investigated the lethal and suble-thal effects of MBe on the generalist predator Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) via different exposure routes. This species is an important natural enemy of thrips, aphids, and mites in biological control programs globally. Acute toxicity bioassays conducted on O. laevigatus showed that the lethal median concentration (LC 50) values of MBe for topical and residual toxicity were 0.73 and 0.94%, respectively, after 24 hr of exposure. Importantly, a sublethal concentration of MBe (LC 30 = 0.51%) did not affect the survival and reproduction of O. laevigatus. In addition, prey consumption by O. laevigatus under different exposure conditions with varying densities of Aphis gossypii (Glover) (Hemiptera: Aphididae) adults demonstrated a good fit for a Type II functional response. The sublethal concentration of MBe did not affect the attack rate and handling time of O. laevigatus compared to untreated insects, nor did it affect the longevity and fecundity of O. laevigatus females. Thus, according to the International Organization for Biological Control, the sublethal MBe concentration for O. laevigatus is categorized as harmless and may be used in conjunction with this predator species for integrated control of many agricultural insect pests. Graphical Abstract Methyl benzoate (MBe) Orius laevigatus Toxicity Acute toxicity (Topical and residual toxicity of MBe against adults of O. laevigatius) Sublethal effects (MBe at sublethal conc. did not affect the development, adult lifespan, reproductive capability, predation ability, repellent, and oviposition choice of O. laevigatius) Lethal and sublethal effects of methyl benzoate
... Therefore, conservation of these natural enemies through the use of reduced-risk chemical pesticides or bioinsecticides against scale insects is crucial for sustaining citrus crop production and productivity in the Mediterranean region. Particularly, the use of eco-friendly botanical insecticides based on plant essential oils as alternative to applying broadspectrum hazardous chemical pesticides has been gaining increased importance over the last decade (Regnault-Roger et al. 2012;Pavela and Benelli 2016;Isman 2020). ...
Article
Applying botanical extracts with potential insecticidal actvity has long been considered a promising eco-friendly alternative to the use of chemical insecticides. In the present study, we evaluated the contact toxicity of Mentha pulegium essential oil (applied at either 2.73 mg/L, 9.56 mg/L, 13.65 mg/L, 27.31 mg/L, or 40.96 mg/L) toward three pest scales, Planococcus citri, Aonidiella aurantii, and Chrysomphalus aonidum, and two chemical insecticides, chlorpyrifos (100 mL/hL) and spirotetramat (120 mL/hL), against P. citri and A. aurantii under laboratoty conditions. Toxicity of M. pulegium essential oil and both insecticides was also assessed on the coccinellid predator Cryptolaemus montrouzieri. The highest mortality rates for all scale insect nymphs (> 97% for A. aurantii and 100% for P. citri or C. aonidum) were obtained following essential oil application at a dose of 40.96 mg/L. Lowest mortality rate (3.6 ± 0.92%) of C. montrouzieri adults was induced by an essential oil application at a dose of 8.95 mg/L, compared to either dose 11.26 mg/L or 17.66 mg/L. Both chemical insecticides significantly affected survival of mealybug and armored scale insect nymphs until 21 days after treatment. Chlorpyrifos, being highly effective against P. citri and A. aurantii, was significantly more toxic than spirotetramat toward both A. aurantii nymphs and predatory C. montrouzieri adults until three weeks after treatment. Using M. pulegium essential oil in combination with spirotetramat could be recommended for eco-friendly, sustainable control of P. citri, A. aurantii and C. aonidum in citrus orchards while minimizing harmful side effects on C. montrouzieri.
... Recently, plant essential oils (EOs), which are complex mixtures of compounds that act as a defense agents against pests and pathogens and provide protection to the plant from heat and cold have attracted attention [322,323]. EOs are also generally recognized as safe biopesticidal agents [324][325][326][327][328]. ...
Article
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The European Spongy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), is an abundant species found in oak woods in Central and Southern Europe, the Near East, and North Africa and is an important economic pest. It is a voracious eater and can completely defoliate entire trees; repeated severe defoliation can add to other stresses, such as weather extremes or human activities. Lymantria dispar is most destructive in its larval stage (caterpillars), stripping away foliage from a broad variety of trees (>500 species). Caterpillar infestation is an underestimated problem; medical literature reports that established populations of caterpillars may cause health problems to people and animals. Inflammatory reactions may occur in most individuals after exposure to setae, independent of previous exposure. Currently, chemical and mechanical methods, natural predators, and silvicultural practices are included for the control of this species. Various insecticides have been used for its control, often through aerial sprayings, which negatively affect biodiversity, frequently fail, and are inappropriate for urban/recreational areas. However, bioinsecticides based on various microorganisms (e.g., entomopathogenic viruses, bacteria, and fungi) as well as technologies such as mating disruption using sex pheromone traps have replaced insecticides for the management of L. dispar.
... Therefore, novel insecticides that are able to kill multiple developmental stages of the same and/or different storage pests are highly desirable. Essential oils are secondary metabolites of plants, extracted by different plant parts like roots, flowers, seeds, and leaves (Bakkali et al., 2008;El Asbahani et al., 2015;Pavela and Benelli, 2016;Campolo et al., 2018). It is well known that many EOs are used extensively by food, cosmetic, and fragrant industries (Bakkali et al., 2008;Tajkarimi et al., 2010;Hyldaard et al., 2012;Stojanović Radić et al., 2012;Guzmán and Lucia, 2021). ...
Article
Carlina acaulis L. is a herb mainly used in central Europe as traditional medicine or food. Recently, C. acaulis essential oil (EO) and its nanoemulsion showed elevated efficacy against several insects of medical and agricultural importance. In the current study, efficacy of C. acaulis EO was estimated against several stored product pests. The EO was sprayed on wheat to control Acarus siro L. (adults, nymphs), Alphitobius diaperinus (Panzer) (adults, larvae), Oryzaephilus surinamensis (L.) (adults, larvae), Rhyzopertha dominica (F.) (adults), Sitophilus oryzae (L.) (adults), Tenebrio molitor L. (adults, larvae), Tribolium castaneum (Herbst) (adults, larvae), and Tribolium confusum Jacquelin du Val (adults, larvae). Carlina acaulis EO was mainly composed by carlina oxide (98.8%), with benzaldehyde (1.2%) and ar-curcumene (traces) as minor components. Both adults and nymphs of A. siro showed high mortality, i.e., 91.1 and 95.6%, after 7 days of initial exposure to 1000 ppm (1000 μL C. acaulis EO/kg wheat), respectively. This concentration provided the death of 25.6% of the exposed A. diaperinus adults at the termination of trials. Total mortality (100.0%) of A. diaperinus larvae was reached 2 and 4 days after initial exposure on wheat sprayed with 1000 and 500 ppm of C. acaulis EO, respectively. One thousand (1000) ppm of EO killed 96.7% of O. surinamensis adults and all larvae 7 and 2 days after initial exposure, respectively. Concerning adults of R. dominica and S. oryzae, 1000 ppm achieved complete mortality after 4 and 6 days of initial exposure, respectively. Tenebrio molitor adults reached 81.1% mortality after their 7-days exposure to 1000 ppm C. acaulis EO. All T. molitor larvae were dead after 7 or 4 days of initial exposure to 500 and 1000 ppm, respectively. Carlina acaulis EO caused 97.8 and 100.0% mortality to adults of T. castaneum after 7 and 5 days of initial exposure to 1000 and 500 ppm, respectively. Complete mortality was observed after 16 h (1000 ppm) and 2 days (500 ppm) of initial exposure for T. castaneum larvae. Similarly, both examined stages of T. confusum achieved 100.0% mortality at the concentrations of 500 and 1000 ppm, after 7 and 4 days (adults), and 1 day and 16 h (larvae) of exposure, respectively. Overall, C. acaulis EO demonstrated pesticidal efficacy higher to pirimiphos-methyl, a conventional organophosphate insecticide, against a wide range of stored-product pests. Therefore this EO represents a reliable option for further developing eco-friendly and non-hazardous pest management strategies.
... The use of essential oils as insecticides (by contact, fumigation, or repellency) has some challenges for future research, including the development of efficient stabilization processes, optimization of the cost of these biopesticides, and improvement in plant growth conditions and extraction processes (Pavela and Benelli 2016). Despite this, the essential oil of P. heptaphyllum has potential as an insecticide against C. maculatus, being more toxic than one of its major compounds. ...
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The present study aimed to investigate the bioactivity of the essential oils of Protium heptaphyllum (Aubl.) (Sapindales: Burseraceae) and its major compound d-limonene in the control of Callosobruchus maculatus (Fabr.) (Coleoptera: Chrysomelidae: Bruchinae). The compounds in the oil were identified by gas chromatography–mass spectrometry (GC–MS). Contact toxicity, fumigation, and repellency tests were conducted. The lethal concentrations for the contact and fumigation tests were determined. In the repellency tests, the lethal concentrations previously determined in the contact test were used. The results showed that d-limonene was the major compound (40.1%) in the essential oil of P. heptaphyllum. d-limonene and P. heptaphyllum oil showed toxicity to C. maculatus in the contact and fumigation tests, and the oil showed higher toxicity (14.23 μL/20 g and 191.28 μL/L air), therefore being more toxic than d-limonene (36.42 μL/20 g and 437.34 μL/L air). The number of insects that emerged in the contact and repellency tests was reduced at all concentrations, which shows that the oil and d-limonene have an ovicidal effect. Repellent effects of P. heptaphyllum and d-limonene on C. maculatus were observed. The essential oil of P. heptaphyllum, which is more toxic than its major compound, has potential as an insecticide against C. maculatus.
... regulation) against insect pests of economic and medical importance (Cao et al. 2018;Ebadollahi and Taghinezhad 2019;Yuan et al. 2019). In addition, they are generally considered safe for vertebrates and non-target organisms (Pavela and Benelli 2016). Despite their valuable biological properties, the commercial use of EOs is delayed because of their low water solubility, high volatility, thermal decomposition, and high oxidation rates (Jesser et al. 2020a; Mossa et al. 2017). ...
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This paper introduces the lethal, sublethal, and ecotoxic effects of peppermint and palmarosa essential oils (EOs) and their polymeric nanoparticles (PNs). The physicochemical analyses indicated that peppermint PNs were polydisperse (PDI > 0.4) with sizes of 381 nm and loading efficiency (LE) of 70.3%, whereas palmarosa PNs were monodisperse (PDI < 0.25) with sizes of 191 nm and LE of 89.7%. EOs and their PNs were evaluated on the adults of rice weevil (Sitophilus oryzae L.) and cigarette beetle (Lasioderma serricorne F.) and the larvae of Culex pipiens pipiens Say. On S. oryzae and L. serricorne, PNs increased EOs’ lethal activity, extended repellent effects for 84 h, and also modified behavioral variables during 24 h. Moreover, EOs and PNs generated toxic effects against C. pipiens pipiens. On the other hand, peppermint and palmarosa EOs and their PNs were not toxic to terrestrial non-target organisms, larvae of mealworm (Tenebrio molitor L.), and nymphs of orange-spotted cockroach (Blaptica dubia S.). In addition, PNs were slightly toxic to aquatic non-target organisms, such as brine shrimp (Artemia salina L.). Therefore, these results show that PNs are a novel and eco-friendly formulation to control insect pests.
... Many studies have been carried out on a new plant diseases treatment based on the use of plant essential oil [11,12]. Essential oils (EOs) are volatile secondary metabolites with complex chemical composition and possess antimicrobial properties. ...
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In subtropical countries, black pod caused by Phytophthora megakarya is one of the main diseases causing drastic losses of cocoa. The synthetic chemicals used to control the pathogen, although effective, could be harmful to Human and environment. The use of natural substances such as essential oils (EO) is necessary. This work aimed to determine the chemical composition of thyme essential oil and its antimicrobial potential against Phytophthora megakarya. Essential oil was extracted by hydrodistillation and the chemical composition was analyzed by gas chromatography couple to mass spectrometry (GC/MS). The evaluation of the antimicrobial activity was done in vitro by agar incorporation and liquid dilution. In situ tests were carried out by spraying the EO on the cocoa cortex after and before infected by the pathogen respectively, for the preventive test and curative healing. Results showed that, the yield of thyme EO was 0.42% with thymol (32.41%), ƴ-terpinene (19.65%) and p-cymene (19.43%) as major components. At 225µl/l, the oil completely inhibited the mycelial growth of P. megakarya while at 400µl/l this oil completely inhibited the germination of zoospores. At 1125 µl/l, thyme EO completely inhibited the necrosis on cocoa pods for preventive test. At the same concentration, the oil significantly reduced (40 %) the necrosis during the curative healing. There was significant correlation between EO concentration and the necrosis formation. These results showed that, thyme essential oil could be used as alternative to fight against black pod disease. However, the formulation of oil and fields essay are needed.
... Though the EO formulations are effective in insect management, they have limitations in use due to their volatility, water-solubility, physical destabilization caused by gravitational separation, flocculation, and coalescence (Pavela and Benelli 2016). The existing gap can be addressed by developing oil-in-water (o/w) emulsion which will facilitate improving the dispersion, availability, and scale down the volatile loss of compounds (Pavoni et al. 2020). ...
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Aedes aegypti is the main vector of yellow fever, chikungunya, Zika, and dengue worldwide and is managed by using chemical insecticides. Though effective, their indiscriminate use brings in associated problems on safety to non-target and the environment. This supports the use of plant-based essential oil (EO) formulations as they are safe to use with limited effect on non-target organisms. Quick volatility and degradation of EO are a hurdle in its use; the present study attempts to develop nanoemulsions (NE) of Trachyspermum ammi EO and its constituent thymol using Tween 80 as surfactant by ultrasonication method. The NE of EO had droplet size ranging from 65 ± 0.7 to 83 ± 0.09 nm and a poly dispersity index (PDI) value of 0.18 ± 0.003 to 0.20 ± 0.07 from 1 to 60 days of storage. The NE of thymol showed a droplet size ranging from 167 ± 1 to 230 ± 1 nm and PDI value of 0.30 ± 0.03 to 0.40 ± 0.008 from 1 to 60 days of storage. The droplet shape of both NEs appeared spherical under a transmission electron microscope (TEM). The larvicidal effect of NEs of EO and thymol was better than BEs (Bulk emulsion) of EO and thymol against Ae. aegypti. Among the NEs, thymol (LC 50 34.89 ppm) had better larvicidal action than EO (LC 50 46.73 ppm). Exposure to NEs of EO and thymol causes the shrinkage of the larval cuticle and inhibited the acetylcholinesterase (AChE) activity in Ae. aegypti. Our findings show the enhanced effect of NEs over BEs which facilitate its use as an alternative control measure for Ae. aegypti.
... Some other approaches could be used for controlling pests, such as botanicals and biological control, vaccination, photopesticides, and acids [16][17][18][19][20][21][22][23]. Searching for alternative control strategies, mainly from plant-based resources, is a promising field [5]. ...
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Botanical insecticides are promising pest control agents. This research investigated the novel pesticidal efficacy of Araucaria heterophylla and Commiphora molmol extracts against four ecto-parasites through treated envelopes. Seven days post-treatment (PT) with 25 mg/mL of C. molmol and A. heterophylla, complete mortality of the camel tick, Hyalomma dromedarii and cattle tick, Rhip-icephalus (Boophilus) annulatus were reached. Against H. dromedarii, the median lethal concentrations (LC50s) of the methanol extracts were 1.13 and 1.04 mg/mL and those of the hexane extracts were 1.47 and 1.38 mg/mL, respectively. The LC50 values of methanol and hexane extracts against R. an-nulatus were 1.09 and 1.41 plus 1.55 and 1.08 mg/mL, respectively. Seven days PT with 12.5 mg/mL, extracts completely controlled Haematopinus eurysternus and Hippobosca maculata; LC50 of Ha. eu-rysternus were 0.56 and 0.62 mg/mL for methanol extracts and 0.55 and 1.00 mg/mL for hexane extracts , respectively, whereas those of Hi. maculata were 0.67 and 0.78 mg/mL for methanol extract and 0.68 and 0.32 mg/mL, respectively, for hexane extracts. C. molmol extracts contained sesquiter-pene, fatty acid esters and phenols, whereas those of A. heterophylla possessed monoterpene, ses-quiterpene, terpene alcohols, fatty acid, and phenols. Consequently, methanol extracts of C. molmol and A. heterophylla were recommended as ecofriendly pesticides.
... Botanical pesticides play an increasingly important role in controlling agricultural pests. The effects of essential oils on the behavior, survival, and reproduction of various pests have been extensively studied (Mossa, 2016;Pavela and benelli, 2016;Sousa et al., 2021). At present, essential oils are considered as ideal potential green pesticides and have been well applied and recognized in forest pest control (Cetin et al., 2010). ...
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In order to find out the biological activity of plant essential oils on armyworm [Mythimna separata (Walker, 1865)] larvae and provide a theoretical basis for the biological control of armyworms, in this study, the antifeedant activity, repellent activity, fumigation activity, contact activity, and synergistic effect on indoxacarb of nine kinds of plant essential oils on armyworm larvae were determined. The results showed that lavender and citronella essential oils had the greatest impact on the antifeedant activity on armyworm larvae, and the antifeedant rate reached 100.00%. Meanwhile, rosemary essential oil revealed the best repellent activity on armyworm larvae with an average dwell time of 0 s at the content of 0.2%. Moreover, tea tree essential oil and lemon essential oil at the content of 2.0% had the best fumigation and contact activity against armyworm larvae, and the corrected mortality rates at 120 h were 86.67 and 66.67%, respectively. In addition, the combination of citronella essential oil and indoxacarb with the ratio of 5:1 had the best synergistic effect on armyworm larvae at 96 h, and the synergistic ratio was reached 100.00%. These findings will guide the development of new insecticides for controlling armyworm larvae.
... Several EOs are currently in a registered status by the European Commission. Some of these are even marked as 'no-risk' for consumers (Campaniello et al. 2010;Pavela and Benelli 2016). In particular, eugenol has no toxicological effect on rats if used at a concentration of 500 mg/kg (rat weight), whereas the estimation of temporary levels for an acceptable daily intake by humans is 2.5 mg/kg (body weight). ...
Article
According to toxicity data, ochratoxin A (OTA) is the second most important mycotoxin and is produced by Aspergillus and Penicillium. As a natural antifungal agent, clove essential oil (CEO) is a substance generally recognised as safe (GRAS) and shows strong activity against fungal pathogens. Here, we aimed to investigate the control efficacy of CEO in nano-emulsions (CEN) against OTA production in licorice roots and rhizomes during storage. The experiments were performed under simulated conditions of all four seasons (i.e. Spring, Summer, Autumn and Winter). Relative humidity (RH) and temperature were simulated in desiccators along with various salt solutions in incubators. Fresh licorice roots were immersed in CEN at various concentrations (150, 300, 600, 1200 and 2400 µl/l). Before utilising the nano-emulsions, we measured their polydispersity index and mean droplet size by the dynamic light scattering (DLS) technique. Also, the chemical composition of the CEO was determined using GC and GC-MS analyses. Sampling was carried out to monitor OTA once every five days. The samples were dried immediately and analysed by high-performance liquid chromatography (HPLC). Results showed that various concentrations of CEN inhibited the growth of fungi and OTA production. The most effective CEN concentrations were 1200 and 2400 µl/l, which reduced OTA production to 19 and 20 ppb under Winter and Autumn conditions, respectively. These results suggest an effective eco-friendly method for the storage of licorice to reduce postharvest fungal decay.
... The use of DEET, on the other hand, has prompted concerns about environmental and human health dangers, particularly in children (Sparks et al., 2018). Essential oils have thus been investigated as alternatives to standard synthetic insecticides due to their repelling properties and low toxicity to the environment, non-target creatures, and people (Pavela and Benelli, 2016). Overuse of synthetic insecticides containing organophosphates to control cockroaches has resulted in major issues that have affected non-target organisms, contaminated land and aquatic habitats, and resulted in insecticide resistance (Soares et al., 2019;Kah et al., 2018) & (Yeguerman et al., 2020). ...
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Background: Natural materials such as plant essential oils provide an exceptional alternative to synthetic pesticides to control pests and decrease the negative impact the environment and human health. The move towards using green products and the continuing need to develop new methods to control and prevent pest infestation is increasing. Pests such as cockroaches have demonstrated a growing resistance against the common synthetic pesticides. However, synthetic pesticides have been shown to have detrimental effects on humans and the environment. Thus, the need to develop safer ways for pest management.
... In this scenario, plants represent a promising reservoir of secondary metabolites with insecticidal [11] and acaricidal activity [12][13][14][15], characterized by a multiple mode of action that reduces the likelihood of resistance development [16,17]. ...
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Chemical characterization of the bulbs of Drimia pancration was conducted to isolate four steroidal saponins (1-4). Earlier, we focused on the structural elucidation of compounds 1-3. Herein, by means of 1H-NMR, 13C-NMR, Nuclear Overhauser Effects (NOE), and 2D-NMR spectra, the full stereochemical structure of 4 is reported, and all the 1H and 13C signals are assigned. Compounds 1-4 were tested for their acaricidal properties against the two-spotted spider mite Tetranychus urticae. Our results showed excellent activity of compound 1, with an LD50 (µg/cm2) of 0.29 and a LD90 (µg/cm2) of 0.96, whereas compounds 2, 3, and 4 showed moderate activity. Furthermore, the acaricidal and cytotoxic properties of the crude extract were also investigated. Of note, after 96 h of exposure, the acaricidal activity of compound 1 was higher than that of the positive control, hexythiazox. Indeed, for compound 1, LD50 and LD90 were 0.29 and 0.96 µg/cm2, respectively, while hexythiazox LD50(90) was 18.7 (132.5) µg/cm2. Additionally, D. pancration extract, after 72 h, induced a high cytotoxic effect in HaCaT and THP-1 cell lines, with an IC50 of 7.37 ± 0.5 µg/mL and 3.50 ± 0.15 µg/mL, respectively. Overall, D. pancration can be considered as a green source of novel acaricides effective against mites of agricultural importance, such as T. urticae, pending proper field validation and the assessment of non-target effects on other invertebrate species.
... A number of botanical extracts with often non-specified mode of action have recently been included in the IRAC MoA classification scheme as part of the 'biologics' group (Sparks et al., 2020). Botanicals have gained considerable attention in agriculture, addressing the need for inexpensive, easily sourced, and biodegradable or environment friendly alternatives to classical pesticides (Isman, 2006;Bajda et al., 2021;Pavela and Benelli, 2016). These alternative tactics, when incorporated into integrated pest management programs, can be used as an effective management tool to delay the development of resistance to conventional insecticides (Khater, 2012). ...
Article
Essential oils (EOs) can provide important alternatives to chemical insecticides in the control of pests. In this study, 12 EOs of native plant species from Iran were evaluated for their adulticidal activity against the house fly. In addition, we examined the insecticidal activity of Zataria multiflora and Rosmarinus officinalis EOs on adult female house flies from pyrethroid and organophosphate resistant and susceptible populations, using both fumigant and topical bioassays. The involvement of detoxification enzymes in susceptibility was investigated with synergism experiments in vivo, while the inhibitory effects of R. officinalis and Zataria multiflora EOs on the activities of cytochrome P450-dependent monooxygenases (P450s), carboxylesterases (CarEs) and glutathione S-transferases (GSTs) were determined by enzymatic inhibition assays in vitro. The EOs of Z. multiflora, Mentha pulegium, R. officinalis and Thymus vulgaris were the most effective against adults in contact topical assays, while oils extracted from Eucalyptus cinerea, Z. multiflora, Citrus sinensis, R. officinalis, Pinus eldarica and Lavandula angustifolia where the most effective in fumigant assays. R. officinalis and Z. multiflora EOs were selected for further investigation and showed higher toxicity against a susceptible population, compared to two insecticide-resistant populations. Correlation analysis suggested cross-resistance between these EOs and pyrethroids in the resistant populations. The toxicity of both EOs on the resistant populations was synergized by three detoxification enzyme inhibitors. Further, in vitro inhibition studies showed that R. officinalis and Z. multiflora EOs more effectively inhibited the activities of the detoxification enzymes from flies of the susceptible population compared to those of the pyrethroid resistant populations. Synergistic and enzymatic assays further revealed that increased activities of P450s, GSTs, and CarEs are possibly involved in the cross-resistance between EOs and pyrethroids. Investigating the molecular mechanisms of P450s, GSTs, and CarEs in the resistance to EOs should be subject to further studies.
... In general, the introduction of plant-based compounds into crop defense strategies, requires the fulfillment of a number of constraints besides the lack of adverse effects and the development of appropriate delivery techniques. Indeed, to obtain the authorization from the regulatory authorities, a complex dossier with data on their stability-presently not available for the majority of these compounds-must be developed [93,97,122]. In addition, the activity of these compounds seems to be not enough reproducible, mostly because of the wide variability of their chemical profile [97,98,123]. ...
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Anthracnose is a severe disease caused by Colletotrichum spp. on several crop species. Fungal infections can occur both in the field and at the post-harvest stage causing severe lesions on fruits and economic losses. Physical treatments and synthetic fungicides have traditionally been the preferred means to control anthracnose adverse effects; however, the urgent need to decrease the use of toxic chemicals led to the investigation of innovative and sustainable protection techniques. Evidence for the efficacy of biological agents and vegetal derivates has been reported; however, their introduction into actual crop protection strategies requires the solutions of several critical issues. Biotechnology-based approaches have also been explored, revealing the opportunity to develop innovative and safe methods for anthracnose management through genome editing and RNA interference technologies. Nevertheless, besides the number of advantages related to their use, e.g., the putative absence of adverse effects due to their high specificity, a number of aspects remain to be clarified to enable their introduction into Integrated Pest Management (IPM) protocols against Colletotrichum spp. disease.
... Better results were also obtained in our previous study (Zouhar et al. 2009), where approximately 90% mortality was observed at 5 000 ppm Thymus vulgaris L. oil concentrations. Differences between the results obtained in this study and those from other studies could be a consequence of the different compositions of these oils; thus, the amounts of different compounds in certain essential oils could vary even among oils from the same plant species obtained from different companies, localities or different growing seasons (Pavela and Benelli 2016). The technique used to obtain plant extracts or essential oils is also of crucial importance. ...
Article
With the need to obtain new methods to protect seed material from Ditylenchus dipsaci (Kühn, 1857) nematodes, a study was conducted to evaluate the nematicidal effects of several plants’ essential oils on the mortality of D. dipsaci. Tests were performed under in vitro conditions; a concentration of 2 000 ppm was tested, nematodes were added into diluted oils, and numbers of living/dead nematodes were scored after 4 and 24 h. The results show a significant effect of several plant essential oils on D. dipsaci mortality, with the highest efficacy found for oil from Cinnamomum cassia ((L.) J. Presl), with 100% mortality observed even after 4 h.
... One particular group of plant secondary metabolites are volatile compounds, also known as essential oils (EOs), which have been used since ancient times in many different traditional healing systems all over the world, due to their biological activities [12]. Due to their antioxidant and antimicrobial properties, these preparations have also found applications as naturally occurring antioxidant and antimicrobial agents in the field of pharmacology, phytopathology, as well as medical and clinical microbiology, for extending the shelf life of food products, or in agriculture as biopesticides [13][14][15]. EOs and their bioactivity have been intensively investigated over recent years. They are recognized to display important antioxidant properties exerting protective effects against cellular oxidative stress [16]. ...
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(1) Background: According to the emergence and spread of antibiotic resistance, there is an urge for new promising substances. The purpose of the study was to test the antioxidant, cytotoxic and antimicrobial properties of the Helichrysum italicum (Roth) G. Don essential oil (EO) and hydrosol. (2) Methods: The antioxidant potential was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. The cytotoxicity for human skin and intestinal cells was tested using primary and immortalized cell line models. The minimum inhibitory concentration (MIC) of hydrosol was then determined for six bacterial strains covering four commonly reported food pathogens. Further on, the hydrosol at a concentration of 1/8 MIC was used to test the antiadhesive effect by the crystal violet (CV) staining method. (3) Results: the EO showed a 100-times higher antioxidant and 180- to 25.000-times higher cytotoxic activity, when compared to hydrosol. Nevertheless, all bacterial strains, with the exception of Staphylococcus aureus, were sensitive to hydrosol in the range of 12.5 % (V/V) for Campylobacter jejuni, to MIC values of 100 % (V/V) for Escherichia coli and Pseudomonas aeruginosa. The antiadhesive potential of hydrosol was also shown. (4) Conclusions: Even though hydrosols are a by-product of the EO distillation process, they possess valuable biological activities.
... The oxidized volatile products. This biodegradation of the FVOs will require some controlled-release system, such as nanotechnological formulations, to optimize the action of their active ingredients (de Oliveira et al., 2014;Pavela and Benelli, 2016;Jumbo et al., 2018). It may be a reason for the gradual decline in the efficacy of the FVOs against C. maculatus. ...
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Fixed vegetable oils (FVOs) possess insecticidal properties against insect pests of stored cowpea, but information on their efficacy over a prolonged storage period is still scanty. Bioassays were conducted to investigate the potentials of oil from castor, groundnut, neem, and palm kernel in protecting stored cowpea seeds against Callosobruchus maculatus Fab. over 180 days. Each FVO was admixed with cowpea at 5.0 mL/kg, untreated seeds served as the control, and treatments were replicated four times. The FVOs significantly decreased the bruchid's population growth rate, reduced seed perforation, minimized loss in seed weight, and preserved seed viability compared to the control. Among the FVOs, neem kernel oil appeared to be a better seed protectant for cowpea. But bioactivity of all the FVOs seemed to be short-lived, given the increase in bruchid infestation and seed damage observed after 90 days of treatment. The highest growth in C. maculatus population was at 120 days. None of the untreated seeds could germinate after 180 days of C. maculatus attacks. The level of infestation and seed damage that occurred after 90 days post-treatment resulted in low germination (<20%) of treated seeds. Our results showed that for a short-term (≤90 days) preservation of cowpea, the FVOs at 5.0 mL/kg could be a valuable tool in the management of C. maculatus attacks.
... Some reports have studied the microencapsulation of selected monoterpenoids (linalool, S-carvone, camphor, geraniol, γ-terpinene and fenchone) on β-cyclodextrin using the co-precipitation method, subsequently proving an insecticidal effect against some stored products pests [56]. Based on this paper and the extant literature [57], the encapsulation method may improve the insecticidal effect of L. stoechas EO by extending the efficacy period while progressively releasing the active compounds of the EOs. ...
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The purpose of this study is to investigate the effect of essential oil medium on the inclusion complex of L. stoechas EO in β-cyclodextrin, as well as to examine the impact of the encapsulating action on the adulticidal activity. In line with this, L. stoechas EO was hydrodistilled and determined through GC-MS. Furthermore, the optimization of EO medium was conducted using a binary mixture design of ethanol and glycerol as green emulsifier solvent. Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray powder diffraction and thermogravimetric analysis were used to verify the establishment of the IC. The insecticidal effect of the created formulation was evaluated against C. pipiens female mosquitoes. The optimum ethanol: glycerol ratio was 0.73: 0.27, corresponding to 58.86% of encapsulation efficiency. The fumigant test showed that, after 24 h of exposure, L. stoechas EO exerted only 24.56 ± 1.04%, while the encapsulated oil killed 57.89% of the adult population. At the highest dose (312.5 μl/L), the encapsulated oil provided the most significant effect on adults (100% mortality after 54 h) compared to non-encapsulated oil (100% mortality after 72 h). The encapsulated form of L. stoechas EO constitutes a promising alternative for the control of mosquitoes that are responsible for human diseases.
... A possible alternative to mitigate these effects is the use of essential oils (EOs) since they have low toxicity to natural enemies, degrade rapidly, have a reduced environmental impact [23], and are compatible with conventional and organic agriculture [24]. EOs are synthesized by the secondary metabolism of aromatic plants and are a rich source of bioactive molecules that contain terpenes with functional groups such as acids, alcohols, ketones, phenols, hydrocarbons, and others [25]. ...
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The spotted wing drosophila (Drosophila suzukii) is one of the main invasive pests of small fruits in the world. Thus, 19 essential oils (EOs) were selected to analyze the effects through toxicity and repellency on oviposition and adults of D. suzukii. In addition, their lethal and sublethal effects on the pupal endoparasitoid Trichopria anastrephae were evaluated. The EOs of C. flexuosus and Mentha spp. had the highest toxicity observed in the topical application bioassay for D. suzukii. In contrast, the EOs of C. verum, C. citratus QT citratus, and C. winterianus showed the highest toxicity in the ingestion bioassay for D. suzukii. The dry residues of C. verum and C. citratus QT citratus reduced the oviposition of D. suzukii. In the repellency bioassays, the 19 EOs analyzed repelled ≅ 90% of females of D. suzukii. All EOs evaluated using LC90 values of the products provided mortality of less than 20% of adults of T. anastrephae, and did not cause reduction to the parasitism of T. anastrephae surviving females. We conclude that the EOs evaluated have the potential to be used in the management of D. suzukii. They can also serve as selective active ingredients for formulating and synthesizing new biopesticides.
... [14,54] We tested the efficacy of a single bottle of each EO, sourced from a single batch extraction of that EO. One point of concern in the use of EOs in greenhouse management is that EOs can vary in quality and consistency among commercial blends, as: (1) The type or percentage of proprietary ingredients of EOs are often not included on the product label, and (2) The quantity of insecticidal phytochemicals can vary from one batch to another within a single product, due to the inherent differences in chemical concentration of the plants from which the EOs are distilled [42]. Fortunately, consumer demand for high quality EOs for therapeutic purposes has resulted in multiple EO manufacturers that test the chemical composition of their products on a regular basis. ...
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Western flower thrips ( Frankliniella occidentalis ; Thysanoptera: Thripidae), or WFT, are a global pest of commercial crops, particularly those grown in greenhouses. Current management recommendations often involve judicious use of pesticides to which WFT have evolved multiple resistance phenotypes. Essential oils (EOs) have shown promise as a less toxic alternative for WFT greenhouse management. However, challenges remain in predicting which EOs are most likely to be insecticidal to WFT and ensuring that the efficacy of EOs under bioassay conditions reflect performance in whole-plant application scenarios. To address these challenges, 9 EOs were tested for contact toxicity against WFT in small container assays, then gas chromatography–mass spectroscopy (GC–MS) profiles of each EO were used to quantify concentrations of 22 chemicals shared by at least 5 or more of the plant species. Of these, 13 compounds were positively correlated with thrips mortality. Effective compounds were a mixture of sesquiterpenes, cyclic monoterpenes, and noncyclic monoterpenes. Interestingly, no bicyclic monoterpenes shared among the essential oils tested correlated with thrips mortality. Whole-plant assays of the four best EOs from the container assay showed significant reduction in the number of thrips per plant, although mortality in EO treatments in the whole plant assay was lower than in the container assay. In addition, all four EOs were as efficacious as the conventional insecticide flonicamid. Identifying other EOs with high concentrations of the efficacious compounds that were identified in this study and using container assays to screen these oils for WFT thrip mortality and phytotoxicity could help integrated pest management (IPM) practitioners and greenhouse staff to more rapidly accumulate a suite of EOs as low toxicity alternatives for management of WFT in greenhouse settings. Graphical Abstract
... Identifying its genomes as well as the significance of its endosymbionts could help researchers better comprehend population reduction and vectors competency [16]. Hence, researchers are finding a suitable biopesticides from various plant sources against mosquito vectors [17]. Hence, in this study the Cymodocea serrulata is a sea grass subjected to extraction and assess their larvicidal and pupicidal activities against C. quinquefasciatus. ...
Article
Finding a potential bioactive compound against a specific mosquito vector is an urgent requirement. Thus, this research was designed to separate the significant compounds present in the crude ethyl acetate extract of Cymodocea serrulata through Thin Layer Chromatography (TLC), Column Chromatography (CC), and High Performance Liquid Chromatography (HPLC). Furthermore, the larvicidal and pupicidal activity of different concentrations (100, 300, 500, 700, and 900 g mL⁻¹) of separated fraction against 4th instar larvae of Culex quinquefasciatus in 24 h of treatment. Interestingly, 7 fractions were obtained from crude ethyl acetate extract by TLC. One fraction (7a) from out of 7 was further separated into fractions 7a and 7b through CC and preparative TLC. Furthermore, the HPLC analysis result revealed that the fraction-7a contained 2 major peaks and 25 minor peaks. The fraction 7a was selected based on the Rf value and examined their larvicidal and pupicidal activity on 4th instar larvae and pupa of C. quinquefasciatus. Interestingly, the increased concentration (900 µg mL⁻¹) of fraction-7a of ethyl acetate extracts of C. serrulata showed excellent larvicidal and pupicidal activities as 98.66 ± 1.88% and 98 ± 5.65%, respectively. These findings imply that the fraction 7a of C. serrulata ethyl acetate extract could be used as a mosquito vector control agent.
... Moreover, these researchers suggest that phytol, (E)-nerolidol and spathulenol can be used as eco-friendly green insecticides against aphids [26]. To support the production of biopesticides, Pavela et al. [27] again conducted research with exogenously applied phytol, which inhibited the invasion of root-knot nematodes into the roots of Arabidopsis Heynh. [28]. ...
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Barrelier’s Speedwell or Veronica barrelieri Schott ex Roem. et Schult. (syn. Pseudolysimachion barrelieri (Schott ex Roem. et Schult.) Holub (family Plantaginaceae) grows on dry grasslands and rocky slopes in southeastern Europe. Because of its attractive blue flowers arranged in dense inflorescences up to 30 cm long, this plant has great potential for horticulture, especially in dry climates. As part of studies on biologically active compounds in this species, free VCs (Volatile Compounds) were analyzed by GC-MS (Gas Chromatography with Mass Spectrometry) and micromorphological features were studied by SEM (Scanning Electron Microscopy). Free VCs from aboveground plant parts collected during flowering were characterized by a considerably high content of oxygenated diterpene phytol, followed by hexadecanoic acids, pentacosane, and caryophyllene oxide. These compounds are most abundant in the composition of VCs isolates of V. barrelieri from all five Croatian localities studied. Non-glandular and two subtypes of capitate glandular trichomes were detected on the stems, leaves and calyx of V. barrelieri. Veronica barrelieri attracts pollinators with its attractive flower appearance and specialized metabolites such as free VCs, which are environmentally friendly and possible natural botanical pesticides.
... Although EOs are generally considered environmentally safe [6,[58][59][60][61], our further research will be directed to testing the effect of EOs on selected characteristics of non-target organisms, with the aim of confirming the environmental safety of botanical insecticide applications based on our selected EOs. It will also be important to study the possibility of increasing the content of EOs in plants, on the one hand by using suitable elicitation methods and on the other hand by developing more profitable cultivation technologies, and technique of extractions [62][63][64] that will lead to a higher yield of EOs, like the case of other aromatic plants. ...
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Recently, spices have attracted the attention of scientists and agrochemical companies for their potential as insecticidal and acaricidal agents, and even as repellents to replace synthetic compounds that are labeled with detrimental impacts on environment and human and animal health. In this framework, the aim of this study was to evaluate the insecticidal potential of the essential oils (EOs) obtained from three Cameroonian aromatic plants, namely Monodora myristica (Gaertn.) Dunal, Xylopia aethiopica (Dunal) A. Rich., and Aframomum citratum (J. Pereira) K. Schum. They were produced by hydrodistillation, with yields of 3.84, 4.89, and 0.85%, respectively. The chemical composition was evaluated by GC-MS analysis. The EOs and their major constituents (i.e., geraniol, sabinene, α-pinene, p-cymene, α-phellandrene, and β-pinene) were tested against the polyphagous moth pest, i.e., Spodoptera littoralis (Boisd.), the common housefly, Musca domestica L., and the filariasis and arbovirus mosquito vector, Culex quinquefasciatus Say. Our results showed that M. myristica and X. aethiopica EOs were the most effective against M. domestica adults, being effective on both males (22.1 µg adult−1) and females (LD50: 29.1 µg adult−1). The M. myristica EO and geraniol showed the highest toxicity on S. littoralis, with LD50(90) values of 29.3 (123.5) and 25.3 (83.2) µg larva−1, respectively. Last, the EOs from M. myristica and X. aethiopica, as well as the major constituents p-cymene and α-phellandrene, were the most toxic against C. quinquefasciatus larvae. The selected EOs may potentially lead to the production of cheap and effective botanical insecticides for African smallholders, although the development of effective formulations, a safety evaluation, and an in-depth study of their efficacy on different insect species are needed.
Chapter
Intensive application of synthetic pesticides was the routine practice of commercial agriculture during the Green Revolution to boost agricultural productivity to meet global food demand. Alongside this, the application of chemical pesticides caused adverse effects on the environment and its ecoreceptors including human health. Negative externalities arising from conventional farming instigated the call for sustainable development during the sixties to promote and balance the nexus between socially acceptable economic growth and environmental protection. Consequently, a blueprint of 17 Sustainable Development Goals (SDGs) and 169 targets including ecological stewardship and food security was drafted. Eight out of the 17 SDGs are directly linked to sustainable agriculture based on the direct impact of agriculture, judicious use of critical resources and conservation and the Principles of green chemistry. As a green chemical agent, biopesticides have been shown to have the potentials to substitute chemical pesticides with equal agricultural productivity. The adoption of bio-based pesticides via integrated pest management (IPM) has proven to be the most effective option to influence most dimensions of sustainable agriculture. Therefore, biopesticide-driven IPM if utilized with requisite education, skills and research would boost sustainable agriculture. This chapter reviews the prospects, importance, and limitations of biopesticides to sustainable agriculture and how sustainable agriculture is connected to sustainable development, Green Chemistry, and integrated pest management.
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Although the use of synthetic chemicals is the principal method for insect pest management, their widespread application has led to numerous side effects, including environmental pollution and threats to human and animal health. Plant essential oils have been introduced as promising natural substitutes for synthetic insecticides. However, high volatility and/or low durability are the main limiting factors for essential oil application for control of insect pests. Accordingly, along with an evaluation of the fumigant toxicity of Eucalyptus largiflorens essential oil against the cowpea weevil, Callosobruchus maculatus, essential oil was nanoencapsulated by two mesoporous silicates, MCM-41 and zeolite 3A, to enhance fumigant persistence and toxicity. The chemical profile of essential oil was also analyzed through gas chromatographic-mass spectrometry. E. largiflorens essential oil showed significant concentration-dependent toxicity against insect pests; a concentration of 5.16 μL/L resulted in 100% mortality after 48 h. The toxicity of essential oil could be attributed to the presence of various insecticidal terpenes, such as spathulenol (15.6%), cryptone (7.0%), and 1,8-cineole (5.8%). Fumigant persistence was increased from 6 days to 19 and 17 days for pure and capsulated essential oil with MCM-41 and Zeolite 3A, respectively. The insect mortality also increased from 99 insects in pure essential oil to 178 and 180 insects in MCM-41 and Zeolite 3A encapsulated formulations, respectively. Therefore, the encapsulation of E. largiflorens essential oil by MCM- 41 and Zeolite 3A is a beneficial method for enhancing its persistence and toxicity against C. maculatus.
Article
Background: Stegobium paniceum (Coleoptera, Anobiidae) is an important pest of stored products causing severe damage to dried Chinese medicinal plant materials (CMPMs). Plant volatiles play an important role in host-searching of insects. The olfactory responses of S. paniceum to the most abundant volatile components of some drugstore attractant CMPMs such as Panax notoginseng, Angelica sinensis, Gastrodia elata, and Peucedanum praeruptorum, namely falcarinol, 3-n-butylphthalide, p-cresol, and β-pinene, respectively, were studied by electroantennography (EAG) and behavioural bioassays in six- and four-arm olfactometers. Results: EAG recordings showed that male and female antennae are able to perceive the test compounds in a wide range of concentrations and in a dose-dependent manner. Moreover, for each dose of different compounds tested, no significant differences were found between the mean male and female EAG responses. In six-arm olfactometer bioassays, S. paniceum exhibited positive responses to falcarinol, 3-n-butylphthalide, p-cresol, and β-pinene at doses of 1, 10, 100, 500, and 1000 μg. The most attractive dose was 500 μg for falcarinol, 100 μg for 3-n-butylphthalide, 500 μg for p-cresol, and 1000 μg for β-pinene. Olfactory preferences of S. paniceum, based on comparison of these four compounds at their optimally attractive concentrations in a four-arm olfactometer, were 3-n-butylphthalide > p-cresol > falcarinol > β-pinene. CONCLUSION The results indicated that the four volatiles of CMPMs are perceived by the peripheral olfactory system of S. paniceum adults and are able to individually elicit a positive chemotaxis in S. paniceum adults confirming the role of chemical cues in host-plant detection and selection of this pest. Further field studies are needed to evaluate the potential of the attractive compounds identified in this study, particularly 3-n-butylphthalide, to be applied as a novel monitoring and control tool against this storage-beetle pest. This article is protected by copyright. All rights reserved.
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Use of secondary metabolites as an alternative to organic pesticides is an eco-friendly and safe strategy in pest management. β-caryophyllene [(1R,4E,9S)-4,11,11-trimethyl-8-methylene bicyclo [7.2.0]undec-4-ene], a natural sesquiterpene is found as an essential oil in many plants like Syzygium aromaticum, Piper nigrum, Cannabis sativa. The present study aims at exploring the insecticidal, genotoxic and cytotoxic potential of β-caryophyllene against common cutworm Spodoptera litura (Fab.), a major polyphagous pest. S. litura larvae were fed on different concentrations (5, 25, 125, 625 and 3125 ppm) of β-caryophyllene. Results revealed delay in larval and pupal period with increase in concentration. Larval mortality increased and adult emergence declined significantly with increase in concentration. Higher concentrations of β-caryophyllene caused pupal and adult deformities. A negative impact of β-caryophyllene was also seen on the nutritional physiology of S. litura. Parameters such as relative growth rate, relative consumption rate, efficiency of conversion of ingested food, efficiency of conversion of digested food and approximate digestibility showed a significant reduction in a dose dependent manner. DNA damage assessed using comet assay revealed significant genotoxic effects at LC30 and LC50 concentrations. There was an increase in tail length, percent tail DNA, tail moment and olive tail moment. Phenol oxidase activity was suppressed at LC50 concentration with respect to control. Total hemocyte count also declined significantly at LC30 and LC50 concentrations as compared to control. β-caryophyllene induced genotoxic and cytotoxic damage affecting the growth and survival of S. litura larvae. Our findings suggest that β-caryophyllene has the potential to be used for the management of insect pests.
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The current study is aimed to investigate the essential oil (EO) yields, chemical compositions, antioxidant and antimicrobial activities of Artemisia vulgaris L. EOs isolated at before flowering, initial flowering and post-flowering growth stages. Before the flowering stage, major constituents of the EO were α-thujone (30.68%) and β-caryophyllene (22.05%). Parallel to plant development, sesquiterpene hydrocarbons (mainly β-caryophyllene) decreased and an increase was recorded in oxygenated monoterpenes, especially in α-thujone. These significant changes of the EO compositions caused various alterations in antioxidant and antimicrobial activities. Antioxidant activities of EOs were drastically decreased as the amount of β-caryophyllene dropped off from 22.05 to 7.92% and α-thujone increased from 30.68 to 47.41%. Spearman's correlation coefficients exhibited that α-thujone was quite weak against oxidative stress. In contrast to antioxidant activities, correlation analysis revealed that antimicrobial activities of EOs were enhanced with the increase of α-thujone.
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Pesticides are widely used in producing food to control pests. However, it has been determined that synthetic pesticides present severe toxicity (residual), while they also result in environmental contamination and development of high-level resistance in some insect species. Due to this, some of these susbtances have been banned or restricted in many countries, which has reduced the number of agrochemicals that can be used for pest control, particularly in the case of crops exported to green markets such as Europe and Asia. Under this scenario, essential oils (EOs) are being increasingly studied as bioinsecticides because they are renewable, natural, biodegradable, non-persistent in the environment and safe to non-target organism and humans. It has been determined that tEOs have repellent, ovicidal, larvicidal, and insecticidal effects against different types of pests, but they also have some drawbacks due to their high volatility and low aqueous solubility. This mini-review focusses on EOs used as bioinsecticides for the control of Curculionidae and on current stabilization techniques, such as nanoencapsulation, to prolog the biocidal effect of EOs against these pests.
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Geraniol esters, such as geranyl acetate, are known to have antimicrobial and insect-repellent action, but their acaricidal activity has been little explored. This study aimed to investigate the solvent-free synthesis of geranyl acetate in batch (BSTR) and fed-batch (FBSTR) stirred tank reactors using the immobilized lipases NS 88011 and Novozym 435 and evaluate its larvicidal activity against the cattle tick Rhipicephalus (Boophilus) microplus. A central composite design (CCD) was used to maximize the synthesis of geranyl acetate in a BSTR. The independent variables were temperature reaction (40 to 60 °C), acetic acid/geraniol molar ratio (1:1 to 1:3), and enzyme loading (1 to 5% w/w in relation to the substrates). Novozym 435 yielded the best results, achieving 99% of geranyl acetate conversion using 1:3 acetic acid/geraniol molar ratio, 60 °C and 5% (w/w) of enzyme loading after 1 h of reaction in a BSTR. In the FBSTR system, a high content of geranyl acetate was obtained (about 80%) in 4 h of reaction using a 1:1 acetic acid/geraniol molar ratio, 60 °C and 5% (w/w) Novozym 435. Geranyl acetate showed potential as an acaricide, with an LC90 of 6.25 mg/mL and 100% mortality at a concentration of 12.5 mg/mL.
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In view of their broad color variation and superior antioxidant activity, carotenoids are widely used in the food, cosmetic, pharmaceutical, and feed industries. Cyanobacteria are well-known producers of commercially important carotenoids, such as β-carotene and zeaxanthin. Furthermore, metabolic engineering of cyanobacteria for the production of valuable carotenoids, such as astaxanthin and lutein, has garnered significant interest in recent years because it offers the advantages of simple cultivation, harvesting, and genetic manipulation. This chapter describes the potential of cyanobacteria as carotenoid producers, the applications of carotenoids, the biological activities exhibited by carotenoids (e.g., antioxidant, cardioprotective, and anticancer), and the recent progress in carotenoid processing technology (e.g., extraction, formulation, and isomerization).
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The sustainability of the agricultural system has faced a constant stream of unforeseen and unavoidable difficulties over the last ten years. Due to certain properties of nanoparticles (NPs), such as absorption effectiveness, form flexibility, responsiveness, the durability of agrochemicals, superior biocompatibility, concentrated distribution size, and large surface area, nanotechnology has provided a varied variety of roles in crop production. Because NPs directly affect how efficiently inputs are managed, using nanosensors makes it simple to tackle problems in modern agricultural fields. NPs play a variety of roles, including those of fertilizers, insecticides, herbicides, and magic bullets that target particular cell components in plants. Numerous scientific studies have clarified that nanostructured materials affect seed germination, mineral nutrition, and the environment. In this chapter, we discussed how NPs are used to detect agricultural pathogens, monitor crop growth, and reduce environmental pressures to meet the growing demand for crop management that is sustainable.
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Numerous plant-based repellents are widely used for personal protection against host-seeking mosquitoes. Vitiveria zizanioides (L.) Nash essential oil and its constituents have demonstrated various mosquito repellent activities. In this study, three chemical actions of vetiver oil and five constituents (terpinen-4-ol, α-terpineol, valencene, vetiverol and vetivone) were characterized against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus by using the high-throughput screening assay system (HITSS). Significant contact escape responses in Ae. aegypti and Ae. albopictus to all test compounds at concentrations between 2.5 and 5% were observed. Spatial repellency responses were also observed in some tested mosquito populations depending upon concentrations. The most significant toxic response on mosquitoes was found at the highest concentration, except for vetivone which had no toxic effect on Ae. aegypti and Ae. albopictus. Results on phototoxic and genotoxic hazard revealed that vetiver oil and their constituents showed no phototoxic potential or any significant genotoxic response. In conclusion, vetiver oil and two constituents, valencene and vetiverol, are potentials as active ingredients for mosquito repellency and present no toxicity.
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Antagonistic storage potential of Tagetes minuta Linnaeus, Eupatorium fortunei Turcz. and Ocimum basilicum L. volatile oils hydrodistillated with main secondary metabolites against two storage pests, Tribolium castaneum and Lasioderma serricorne adults were evaluated. More than 95% volatile secondary metabolites obtained at different hydrodistillation time were identified by gas chromatography-mass spectrometry (GC-MS), and analyzed with principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). Further insecticidal assay exhibited interesting results that T. minuta oil showed the strongest fumigant toxicity against both T. castaneum (LC50 = 6.68 mg/L air) and L. serricorne (LC50 = 3.13 mg/L air) among the three essential oils. As one of the main volatile secondary metabolites, methylthymol was found to possess more powerful fumigant (LC50 = 2.42 mg/L air) and contact toxicity (LD50 = 5.43 µg/adult) against T. castaneum. While, precocene I exhibited the strongest insecticidal toxicity on L. serricorne with the LC50 value of 0.88 mg/L air and LD50 of 3.46 µg/adult, respectively. During the repellent assay, T. minuta oil showed the same repellent rate against both T. castaneum and L. serricorne at the highest concentration of 78.63 nL/cm². The results proved that the essential oils as well as the main volatile secondary metabolites have potential to be developed into novel natural botanical resources on antagonistic storage with traditional Chinese medicine (TCM).
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Disease management is important to ensure sustainability in crop production. The increasing evolution of resistance to existing pesticides and bactericides and their adverse effects on the environment and human health have resulted in an increased public health burden, urging more research to explore alternative sustainable disease management strategies. This chapter intends to provide an overview of the use of essential oils (EO) as natural biocides against plant pathogens. EO with reported specific antibacterial mechanisms, especially anti-biofilm and anti-quorum sensing effects, are highlighted. Finally, challenges for biocides development from the plant bacterial pathosystem perspective and knowledge gaps in existing research are identified, leading to consideration of several ideas for future research.
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Red imported fire ant (RIFA), Solenopsis invicta Buren, which is an invasive alien ant, causes serious ecological and public safety problems. Concerns about the impact of traditional synthetic pesticides on nontarget organisms, plant essential oils (EOs) as alternative products with lower environmental impact can be used to control insects. The "push-pull" strategy is considered to be a method of controlling the number and distribution of pests through attraction and repulsion. To find active compounds with effect on the behavior of RIFA, 6 types of EO of plant flowers with a strong aroma, including Osmanthus fragrans (Thunb.) Lour., Sophora japonica Linn, Eugenia caryophμllata Thunb., Ligustrum compactum (Wall. exG. Don) Hook.f., Jasminum sambac (L.) Ait., Allium polyrhizum Turcz. Ex Regel were studied by Y-tube experiment, electrophysiological detection (EAG), and gas chromatography-electroantennographic detection (GC-EAD). The results showed that different concentrations of six EOs significantly affected the behavioral selectivity of different castes of RIFA, the data of high concentration-repellent and low concentration-attractive have been recorded. The repellent rate of 1000 μg/ml L. compactum of EO was 68.75 % and the attraction rate of 2 μg/ml of EO was 66.25 % on small worker ants. For large worker ants, both 1000 μg/ml (repellent rate: 72.50 %) and 40 μg/ml (attractive rate: 68.75 %) of L. compactum EO reached an extremely significant difference. As for E. caryophμllata EOs, the repellent rate of male ants was 67.5 % at 1000 μg/ml and 68.75 % of the attraction rate was calculated at 2 μg/ml. The most interesting finding was that all concentrations of L. compactum EOs showed a remarkable attractive effect on virgin ants and the attraction rate of 1000 μg/ml EO reached an extremely significant difference (attraction rate: 72.5 %). The highest absolute EAG values of different castes of RIFA in the EO were followed as: small worker ants (1.8788 mV, J. sambac), large worker ants (1.5550 mV, O. fragrans), male ants (1.6088 mV, A. polyrhizum), and virgin ants (1.2350 mV, E. caryophμllata). The GC-MS results of the EOs were followed as: the compounds with high content in O. fragrans EO were butyl phthalate (37.95 %) and p-methoxyphenethyl alcohol (16.76 %); the main chemical components in S. japonica EO were benzeneethanol (20.62 %) and phenol (11.16 %); the total contents of eugenol (82.5 %) and aceteugenol (15.81 %) reached 98.31 % in E. caryophμllata EO; the most compound of EO was benzyl alcohol (19.33 %), followed by linalool (18.70 %) in J. sambac EO; the main chemical components of L. compactum EO were benzyl alcohol (17.45 %) and phenethyl alcohol (27.63 %); five compounds, including pentacosane (11.78 %), heptacosane (10.37 %), oleylamide (11.9 %), non-acosane (20.15 %), and octacosane (8.24 %) were the main chemical components in A. polyrhizum EO. The GC-EAD results showed that three compounds (estragole, α-humulene, and caffeine) were identified to have the potential to develop as behavioral orienting chemicals against worker ants of RIFA. Furthermore, several compounds were expected to be developed as attractants for reproductive ants, including eugenol, cis-linalool oxide, furfural, and its analogs. Our data will provide basic materials for the "push-pull" strategy and have the potential to lay the foundation for the eventual development of efficient and safe repellents.
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The mosquito larvicidal activity of Zanthoxylum monophyllum leaf essential oil (EO) and its major chemical constituents was tested against the three mosquito vectors Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus. In the EO of Z. monophyllum, it contains 36 compounds with the two major compounds being Germacrene D-4-ol (19.40 %) and α-Cadinol (12.30). The larvicidal activity of the essential oil against An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus was determined and LC50 values were estimated at 41.50, 45.35 and 49.01 µg/mL, respectively. The two major compounds Germacrene D-4-ol and α-Cadinol were tested for acute toxicity against larvae of the three mosquito vectors. Germacrene D-4-ol showed a significantly higher efficacy compared to α-Cadinol. While LC50 for Germacrene D-4-ol ranged from 6.12 to 7.26 µg/mL, LC50 values for α-Cadinol were estimated in the range from 10.27 to 12.28 µg/mL. The EO, Germacrene D-4-ol and α-Cadinol were found safer to the non-target organism Gambusia affinis (LC50 = 4234.07, 414.05 and 635.12 µg/mL, respectively), which was manifested in the high suitability of the index/predator safety factor value, ranging from 86.36 for the least sensitive larvae of Cx. tritaeniorhynchus to 102.02 for the most sensitive larvae of An. subpictus.
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The fight against mosquito-borne diseases is a challenge of huge public health importance. To our mind, 2015 was an extraordinary year for malaria control, due to three hot news: the Nobel Prize to Youyou Tu for the discovery of artemisinin, the development of the first vaccine against Plasmodium falciparum malaria [i.e. RTS,S/AS01 (RTS,S)], and the fall of malaria infection rates worldwide, with special reference to sub-Saharan Africa. However, there are major challenges that still deserve attention, in order to boost malaria prevention and control. Indeed, parasite strains resistant to artemisinin have been detected, and RTS,S vaccine does not offer protection against Plasmodium vivax malaria, which predominates in many countries outside of Africa. Furthermore, the recent outbreaks of Zika virus infections, occurring in South America, Central America and the Caribbean, represent the most recent of four arrivals of important arboviruses in the Western Hemisphere, over the last 20 years. Zika virus follows dengue (which slyly arrived in the hemisphere over decades and became more aggressive in the 1990s), West Nile virus (emerged in 1999) and chikungunya (emerged in 2013). Notably, there are no specific treatments for these arboviruses. The emerging scenario highlights that the effective and eco-friendly control of mosquito vectors, with special reference to highly invasive species such as Aedes aegypti and Aedes albopictus, is crucial. The concrete potential of screening plant species as sources of metabolites for parasitological purposes is worthy of attention, as elucidated by the Y. Tu’s example. Notably, plant-borne molecules are often effective at few parts per million against Aedes, Ochlerotatus, Anopheles and Culex young instars, can be used for the rapid synthesis of mosquitocidal nanoformulations and even employed to prepare cheap repellents with low human toxicity. In addition, behaviour-based control tools relying to the employ of sound traps and the manipulation of swarming behaviour (i.e. “lure and kill” approach) are discussed. The importance of further research on the chemical cues routing mosquito swarming and mating dynamics is highlighted. Besides radiation, transgenic and symbiont-based mosquito control approaches, an effective option may be the employ of biological control agents of mosquito young instars, in the presence of ultra-low quantities of nanoformulated botanicals, which boost their predation rates.
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Insecticide resistance is one of the most important evolutionary phenomena for researchers. Overuse of chemicals has induced resistance in insect pests that ultimately has led to the collapse of disease control programs in many countries. The erroneous and inappropriate management of insect vectors has resulted in dissemination of many vector-borne diseases like dengue, malaria, diarrhea, leishmaniasis, and many others. In most cases, the emergence of new diseases and the revival of old ones can be related with ecological changes that have favored rapid growth of vector densities. Understanding molecular mechanisms in resistant strains can assist in the development of management programs to control the development and spread of resistant insect populations. The dominant, recessive, and co-dominant forms of genes encoding resistance can be investigated, and furthermore, resistance development can be addressed either by the release of susceptible strains or timely insecticide rotation. The present review discusses the resistance level in all important insect vectors of human diseases; the molecular basis of evolvement of resistance has also been discussed.
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Mosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. Mosquito young instars are usually targeted with organophosphates, insect growth regulators and microbial control agents. Indoors residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have strong negative effects on human health and the environment. Newer and safer tools have been recently implemented to enhance control of mosquitoes. In this review, I focus on characterization, effectiveness, and non-target effects of mosquitocidal nanoparticles synthesized using botanical products (mosquitocidal nanoparticles, MNP). The majority of plant-fabricated MNP are silver ones. The synthesis of MNP is usually confirmed by UV-visualization spectroscopy, followed by scanning electron microscopy or transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction studies. Interestingly, plant-synthesized metal nanoparticles have been reported as effective ovicides, larvicides, pupicides, adulticides, and oviposition deterrents against different mosquito species of medical and veterinary importance. Few parts per million of different MNP are highly toxic against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti, and the filariasis mosquito Culex quiquefasciatus. However, despite the growing number of evidences about the effectiveness of MNP, moderate efforts have been carried out to shed light on their possible non-target effects against mosquito's natural enemies and other aquatic organisms. In the final section, particular attention was dedicated to this issue. A number of hot areas that need further research and cooperation among parasitologists and entomologists are highlighted.
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The essential oils have been widely used as antiparasitical, bactericidal, fungicidal, antivirus and insecticidal. On the other hand the main method to control insect pest is using synthetic pesticides, but the development of insect resistance to this products, the high operational cost and environmental pollution have created the need for developing alternative approaches to control many insects pest, and in this sense the essential oils are an alternative to control many insects. This work is a review for the last five years, which shows the main essential oils from 30 botanical families with activity against coleopterans insect pest in stored grains. It was found that 22 species belong to the family Lamiaceae 17 of Asteraceae and 10 of Myrtaceae
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The efficacy of an essential oil obtained from Pimpinella anisum fruits and its major compound, trans-Anethole, was tested on the eggs, larvae and adults of Culex quinquefasciatus. While causing no significant mortality on eggs, other tested stages were very sensitive to the essential oil and trans-Anethole. LC50 for the 2nd to 4th instar larvae was estimated as 26-27 mu L center dot L-1 and 15-19 mu L center dot L-1 for the essential oil and trans-Anethole, respectively. As for the essential oil applied on adults, LC(LD)(50) was estimated as 9.3 mu L mL(-1) (spray test), 1.9 mu L L-1 (fumigation test) and 0.6 mu g cm(-2) (tarsal test), and for trans-Anethole as 8.1 mu L mL(-1) (spray test), 2.1 mu L L-1 (fumigation test) and 0.4 mu g cm(-2) (tarsal test). The time needed to achieve 50% mortality after application of LC(LD)99 of the essential oil was significantly different; for example, in larvicidal assays it ranged from 15 to 235 mffi depending on the larval instar, and from 9 to 180 mffi when applied to adults, depending on the mode of application. It was also found that temperature had an important effect on the larvicidal efficacy of the essential oil, and oviposition deterrent activity was studied. The essential oil and trans-Anethole were toxic for Daphnia magna (62-92% mortality) and significantly reduced its fertility at high concentrations (35-50 mu L mL(-1)) and long exposure (48 h). However, no negative effect on Daphnia mortality or fertility was found at shorter exposure times (6 h) and/or lower concentrations (20 mu L mL(-1)). Based on the results of this study, we can recommend the essential oil from P. anisum as a suitable active substance for potential botanical insecticides.
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The present investigation reports on the chemical composition of Cudrania tricuspidata fruit essential oil (CTEO) and examines its possible antimicrobial mode of action against food-borne pathogenic bacteria. The CTEO was obtained by hydrodistillation of C. tricuspidata fruits using a microwave-assisted extraction technique. Gas chromatography-mass spectrometry analysis of the CTEO resulted in the determination of 29 different compounds, representing 94.46% of the total oil. The CTEO (1000 μg/disc) showed potential antibacterial effect as diameters of inhibition zones (15.0 ± 0.1–21.0 ± 1.0 mm) against the tested food-borne pathogenic bacteria including Bacillus cereus ATCC 13061, Staphylococcus aureus ATCC 12600, Listeria monocytogenes ATCC 7644, Salmonella typhimurium ATCC 43174 and Escherichia coli O157:H7 ATCC 43889. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentration values of CTEO against the tested bacteria were found in the range of 250–1000 μg/mL, respectively. Also the CTEO had potential inhibitory effect on the cell viability of the tested pathogens at MIC concentration. The SEM analysis showed the inhibitory effect of CTEO as confirmed by considerable morphological alterations on the cell wall B. cereus ATCC 13061 and E. coli O157:H7 ATCC 43889. In addition, the CTEO revealed its mode of action on membrane integrity as confirmed by release of extracellular ATP, loss of 260-nm absorbing materials and leakage of potassium ions against food-borne pathogenic bacteria. These findings suggest that CTEO showed a broad-spectrum of antibacterial efficacy and compromise its mode of action on membrane integrity.
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Recent studies proved that monoterpenoids could be an alternative to synthetic insecticides against stored-product pests. For that reason, it is necessary to learn the mode of action of these monoterpenoids. Inhibition of acetylcholinesterase (AChE) activity as a possible mode of action by 8 monoterpenoids which cause high mortality of three stored-product insect pests, Sitophilus oryzae L. (Coleoptera: Curculionidae), Rhyzopertha dominica Fabricius (Coleoptera: Bostrichidae) and Cryptolestes pusillus Schönherr (Coleoptera: Cucujidae) and the role of these monoterpenoids as inhibitors were examined. Inhibition of AChE was measured by colorimetric method where a chemical reaction with enzyme acetylcholinesterase, a substrate (acetylthiocoline iodide), the Ellman's reagent and each monoterpenoid as inhibitor was carried out. The majority of monoterpenoids tested inhibited the enzyme acetylcholinesterase; fenchone, S-carvone and linalool produced the highest inhibition. Furthermore, it was observed that fenchone, γ-terpinene, geraniol and linalool showed a reversible competitive inhibition at least at the enzyme's hydrophobic active site. S-carvone, estragole and camphor produced a mixed inhibition for this enzyme binding to either the free enzyme or the enzyme–substrate complex which links to a different site from the active site where the substrate binds. No inhibition of enzyme acetylcholinesterase by E-anethole was observed.
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In spite of intensive research on plant natural products and insect-plant chemical interactions over the past three decades, only two new types of botanical insecticides have been commercialized with any success in the past 15 years, those based on neem seed extracts (azadirachtin), and those based on plant essential oils. Certain plant essential oils, obtained through steam distillation and rich in mono- and sesquiterpenes and related phenols, are widely used in the flavouring and fragrance industries and in aromatherapy. Some aromatic plants have traditionally been used for stored product protection, but the potential for development of pesticides from plant essential oils for use in a wide range of pest management applications has only recently been realized. Many plant essential oils and their major terpenoid constituents are neurotoxic to insects and mites and behaviourally active at sublethal concentrations. Most plant essential oils are complex mixtures. In our laboratory we have demonstrated that individual constituents of oils rarely account for a major share of the respective oil's toxicity. Further, our results suggest synergy among constituents, including among those that appear non-toxic in isolation. Repellent effects may be particularly useful in applications against public health and domestic pests, but may be useful in specific agricultural applications as well. In all of these applications, there is a premium on human and animal safety that takes priority over absolute efficacy. In agriculture, the main market niche for essential oil-based pesticides is in organic food production, at least in developed countries, where there are fewer competing pest management products. There is also scope for mixing these oils with conventional insecticides and for enhancing their efficacy with natural synergists. Some examples of field efficacy against agricultural pests are discussed.
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In recent years, the use of essential oils (EOs) derived from aromatic plants as low-risk insecticides has increased considerably owing to their popularity with organic growers and environmentally conscious consumers. EOs are easily produced by steam distillation of plant material and contain many volatile, low-molecular-weight terpenes and phenolics. The major plant families from which EOs are extracted include Myrtaceae, Lauraceae, Lamiaceae, and Asteraceae. EOs have repellent, insecticidal, and growth-reducing effects on a variety of insects. They have been used effectively to control preharvest and postharvest phytophagous insects and as insect repellents for biting flies and for home and garden insects. The compounds exert their activities on insects through neurotoxic effects involving several mechanisms, notably through GABA, octopamine synapses, and the inhibition of acetylcholinesterase. With a few exceptions, their mammalian toxicity is low and environmental persistence is short. Registration has been the main bottleneck in putting new products on the market, but more EOs have been approved for use in the United States than elsewhere owing to reduced-risk processes for these materials. "I am pleased to provide you complimentary one-time access to my Annual Reviews article as a PDF file, for your own personal use. Any further/multiple distribution, publication, or commercial usage of this copyrighted material requires submission of a permission request addressed to the Copyright Clearance Center (http://www.copyright.com/).". You may access the pdf at: http://arjournals.annualreviews.org/eprint/IbA58Imu4RCuBcyc4uUi/full/10.1146/annurev-ento-120710-100554
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Volatile terpenoids released from different plant parts play crucial roles in pollinator attraction, plant defense, and interaction with the surrounding environment. Two distinct pathways localized in different subcellular compartments are responsible for the biosynthesis of these compounds. Recent advances in the characterization of genes and enzymes responsible for substrate and end product biosynthesis as well as efforts in metabolic engineering have revealed new aspects of volatile terpenoid biosynthesis. This review summarizes recent progress in the characterization of volatile terpenoid biosynthetic genes, their spatio-temporal expression patterns and subcellular localization of corresponding proteins. In addition, recent information obtained from metabolic engineering is discussed.
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Currently, the use of synthetic chemicals to control insects and arthropods raises several concerns related to environment and human health. An alternative is to use natural products that possess good efficacy and are environmentally friendly. Among those chemicals, essential oils from plants belonging to several species have been extensively tested to assess their repellent properties as a valuable natural resource. The essential oils whose repellent activities have been demonstrated, as well as the importance of the synergistic effects among their components are the main focus of this review. Essential oils are volatile mixtures of hydrocarbons with a diversity of functional groups, and their repellent activity has been linked to the presence of monoterpenes and sesquiterpenes. However, in some cases, these chemicals can work synergistically, improving their effectiveness. In addition, the use of other natural products in the mixture, such as vanillin, could increase the protection time, potentiating the repellent effect of some essential oils. Among the plant families with promising essential oils used as repellents, Cymbopogon spp., Ocimum spp. and Eucalyptus spp. are the most cited. Individual compounds present in these mixtures with high repellent activity include alpha-pinene, limonene, citronellol, citronellal, camphor and thymol. Finally, although from an economical point of view synthetic chemicals are still more frequently used as repellents than essential oils, these natural products have the potential to provide efficient, and safer repellents for humans and the environment.
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Bioactive oils are commonly used for their pharmaceutical, cosmetic and nutritional properties. Generally, these are volatile substances sensitive to oxygen, light, moisture, and heat. These reported special characteristics could diminish their applicability in the use of cosmetics, food and pharmaceutical industry. Thus, encapsulation is one of the most efficient methods for the formulation of bioactive oils and various investigations have been developed in this aspect. The encapsulation system is selected in line with the intended usage of the final formulation, which can vary depending on the size, shape or nature of selling components. In this review, we state an overview on the different systems for the encapsulation of bioactive oils, as well as, the elaboration methods currently utilized.
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The seeking of new alternatives of synthetic insecticides for the safe environment and health has become an important issue of scientific research which may enable us to obtain safe foods. Although botanical insecticides (BIs) can never entirely replace the amounts of produced synthetic insecticides, they may significantly contribute to seeking the solution of problems associated with application of synthetic pesticides. Three most important arguments support the use of BIs: environmental safety, low or no toxicity for vertebrates and prevention of resistance development. The above-mentioned assets of BIs make us believe in the need of increasing the society-wide efforts leading to further expansion of practical use of these products. However, despite these assets, several limiting factors are associated with BIs that prevent their wider use or restrict their practical applications. This chapter is an effort to critically summarise the advantages and disadvantages of botanical insecticides including major factors that pose limitations to their practical use.
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Botanical insecticides continue to be a subject of keen interest among the international research community, reflected in the steady growth of scientific publications devoted to the subject. Until very recently though, the translation of that theory to practice, i.e., the commercialization and adoption of new botanical insecticides in the marketplace, has seriously lagged behind. Strict regulatory regimes, long the bane of small pesticide producers, are beginning to relax some of the data requirements for "low risk" pesticide products, facilitating movement of more botanicals into the commercial arena. In this paper I discuss some of the jurisdictions where botanicals are increasingly finding favour, some of the newer botanical insecticides in the plant and animal health arsenal, and some of the specific sectors where botanicals are most likely to compete effectively with other types of insecticidal products. This article is protected by copyright. All rights reserved.
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The efficacy of 30 aromatic compounds and their mutual binary combinations was assessed for acute toxicity against the larvae Culex quinquefasciatus. Based on comparison of the lethal doses, thymol and p-cymene were selected as the most effective (LD50 = 18 and 21 mg L(-1), respectively, and LD90 = 25 and 30 mg L(-1), respectively). Although the LD50 for terpinolene and trans-anethole was also estimated at 21 mg L(-1), their LD90 was significantly higher compared to the substances above (245 and 34 mg L(-1), respectively). In total, 435 binary combinations were tested, of which 249 combinations showed a significant synergistic effect, while 74 combinations showed a significant antagonistic effect on mortality. Only nine substances were identified as being able to create a synergistic effect with more than 20 substances: limonene, trans-anethole, 4-allylanisole, carvacrol, isoeugenol, menthone, carvone, borneol, and camphor. The highest synergistic effect on larval mortality was achieved for the combinations: eugenol and isoeugenol, carvone and carvacrol, carvone and 4-allylanisole, carvone and α-terpineol, carvone and menthone, limonene and trans-anethole, limonene and menthone, α-pinene and menthone, β-citronellol and menthone, carvacrol and 4-allylanisole, carvacrol and terpineol, α-terpinene and trans-anethole, camphor and menthone, camphene and menthone, and 4-allylanisole and menthone. Significant differences between achieved mortality and the mutual mixing ratio were found for the five selected binary mixtures that had shown the most significant synergistic effect in the previous tests. The mixture of limonene and trans-anethole showed the highest mortality, with the mixing ratio 1:1; the mixture of eugenol and isoeugenol caused 90.2 % mortality, with the mixing ratio 1:3. One hundred percent mortality was achieved if carvacrol was contained in a mixture with carvone in a ratio >2. After a comparison of all our results, based on our experiments, we can choose two pairs that caused mortality higher than 90 % in concentrations lower than 20 mg L(-1): limonene and trans-anethole (with the mixing ratio 1:1), and carvone and carvacrol (with the mixing ratio 1:2-3). The information gained can thus be used in the development of new botanical insecticides based on essential oils (EOs) and particularly in the creation of formulations.
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Mosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating pathogens and parasites. In this scenario, vector control is crucial. Mosquito larvae are usually targeted using organophosphates, insect growth regulators, and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment and induce resistance in a number of vectors. Newer and safer tools have been recently implemented to enhance control of mosquitoes. Here, I focus on some crucial challenges about eco-friendly control of mosquito vectors, mainly the improvement of behavior-based control strategies (sterile insect technique ("SIT") and "boosted SIT") and plant-borne mosquitocidals, including green-synthesized nanoparticles. A number of hot areas that need further research and cooperation among parasitologists, entomologists, and behavioral ecologists are highlighted.
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Essential oils (EOs) and their main constituent compounds have been extensively investigated due to their application in the food industry for improving the shelf life of perishable products. Although they are still not available for use in food packaging in the market in Europe, considerable research in this field has been carried out recently. The safety of these EOs should be guaranteed before being commercialized. The aim of this work was to review the scientific publications, with a primary focus on the last 10 years, with respect to different in vitro toxicological aspects, mainly focussed on mutagenicity/genotoxicity. In general, fewer genotoxic studies have been reported on EOs in comparison to their main components, and most of them did not show mutagenic activity. However, more studies are needed in this field since the guidelines of the European Food Safety Authority have not always being followed accurately. The mutagenic/genotoxic activities of these substances have been related to metabolic activation. Therefore, in vivo tests are required to confirm the absence of genotoxic effects. Considering the great variability of the EOs and their main compounds, a case-by-case evaluation is needed to assure their safe use in food packaging. Copyright © 2015. Published by Elsevier Ltd.
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Plant essential oils are usually complex mixtures, and many factors can affect their chemical composition. To identify relationships between composition and bioactivity of the constituents, comparative and synergistic interactions of the major constituents of rosemary essential oil were evaluated against third instar larvae and an ovarian cell line of the cabbage looper, Trichoplusia ni via different methods of application. The major constituents of the rosemary oil we used were 1,8-cineole, (±)-camphor, (+)-α-pinene and camphene. Via topical application to larvae, 1,8-cineole was identified as the major active compound, whereas via fumigation, 1,8-cineole and (±)-camphor, and in a cytotoxicity assay, (+)-α-pinene, were determined to be the major active principles. Several combinations of these constituents exhibited synergistic insecticidal activities when topically applied, particularly among combinations of three major constituents, (±)-camphor, (+)-α-pinene, and camphene. A binary mixture of 1,8-cineole and (±)-camphor showed enhanced activity, with a synergy ratio of 1.72. Based on our results, the insecticidal activity of rosemary oil appears to be a consequence of the synergistic interaction between 1,8-cineole and (±)-camphor, and (±)-camphor should be considered a promising synergizing agent. This article is protected by copyright. All rights reserved.
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Background Plant extracts and by-products furnish various alternative products for crop protection and are traditionally used by farmers. But the cost and timeframe for their registration as active substances are prohibitive for small companies and farmers’ associations with the new Plant Protection Products (PPP) Regulation (EC) No 1107/2009. However, there is now a possibility to register light compounds as “Basic Substances”, a new category described in article 23 and in the “whereas/ recital (18)”.ResultsWe developed a regulatory expertise on the approval of such products in the framework of the PPP regulation. A Draft Assessment Report in one volume was established, later transformed by EC Directorate into a Basic Substance Application Template, and subsequently used by the EC as a matrix for the corresponding Guidelines for applicants (SANCO 10363/2012 rev. 9). Here we provide further tools, consisting in methodological, linguistic and strategic recommendations in order to constitute a Basic Substance Application (BSA) and proceed to its registration.Conclusion While the use of alternative agents for crop protection is increasing both in organic and conventional agriculture, these usages are still considered as “minor uses”. Our approach and tools are valuable to non-PPP specialized applicants for simplifying and facilitating their submission of the BSA.
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Neonicotinoids are now the most widely used insecticides in the world. They act systemically, travelling through plant tissues and protecting all parts of the crop, and are widely applied as seed dressings. As neurotoxins with high toxicity to most arthropods, they provide effective pest control and have numerous uses in arable farming and horticulture.However, the prophylactic use of broad-spectrum pesticides goes against the long-established principles of integrated pest management (IPM), leading to environmental concerns.It has recently emerged that neonicotinoids can persist and accumulate in soils. They are water soluble and prone to leaching into waterways. Being systemic, they are found in nectar and pollen of treated crops. Reported levels in soils, waterways, field margin plants and floral resources overlap substantially with concentrations that are sufficient to control pests in crops, and commonly exceed the LC50 (the concentration which kills 50% of individuals) for beneficial organisms. Concentrations in nectar and pollen in crops are sufficient to impact substantially on colony reproduction in bumblebees.Although vertebrates are less susceptible than arthropods, consumption of small numbers of dressed seeds offers a route to direct mortality in birds and mammals.Synthesis and applications. Major knowledge gaps remain, but current use of neonicotinoids is likely to be impacting on a broad range of non-target taxa including pollinators and soil and aquatic invertebrates and hence threatens a range of ecosystem services.