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Novel advances with plant saponins as natural insecticides to control pest insects

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Abstract

Saponins are a class of secondary plant metabolites with diverse biological properties. They occur in a great number of plant species (mainly Angiosperms), both wild plants and cultivated crops. Triterpenoid saponins are mostly found in dicotyledonous species, while many of the major steroidal saponins are synthesized by monocots, such as members of the Liliaceae, Dioscoraceae and Agavaceae families. Many legumes contain saponins, such as soybeans, beans, peas, tea, spinach, sugar beet and quinoa, oats, capsicum peppers, aubergine, tomato seed, alliums and asparagus. Saponins possess clear insecticidal activities: they exert a strong and rapid-working action against a broad range of pest insects that is different from neurotoxicity. The most observed effects are increased mortality, lowered food intake, weight reduction, retardation in development and decreased reproduction. According to the main hypotheses in literature, saponins exert a repellent/deterrent activity, bear digestive problems, provoke insect moulting defects or cause cellular toxicity effects. As a con-sequence these interesting plant components open new strategies to protect crops in modern agriculture and horticulture with integrated pest management (IPM) programs against pest insects, either by spraying, or by selecting high-saponin varieties of commercial crops.

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... It is reported that oxidosqualene cyclization can proceed via the "chair-chairchair" or via the 'chair-boat-chair' conformation. Triterpenes saponins originate from the 'chair-chair-chair' conformation, while steroids saponins arise from the 'chair-boat-chair conformation [11] . ...
... Acid hydrolysis is generally used to identity the sugars portion. The literature commonly reports acid hydrolysis or HCl [9][10][11][12][13] or H2SO4 [8][9][10][11][12][13][14][15][16] . ...
... Acid hydrolysis is generally used to identity the sugars portion. The literature commonly reports acid hydrolysis or HCl [9][10][11][12][13] or H2SO4 [8][9][10][11][12][13][14][15][16] . ...
Article
Saponinas esteroidais são uma importante classe de metabólidos secundários, estas são amplamente distribuídas em muitas espécies de plantas e são caracterizadas como princípio ativos destes produtos naturais. Saponinas tem sido investigadas ao longo dos anos, devido as suas potentes propriedades terapêuticas. Neste trabalho foram resumidos os estudos encontrados na literatura científica acerca das investigações das atividades biológicas e caracterização estrutural de saponinas esteroidais. Estudos recentes tem sugerido algumas saponinas como candidatas ao tratamento de pacientes com a doença do Coronavirus (COVID-19).
... Tech niques to sup press pop u la tion out breaks of in sect pests may de crease 20 -30% of an nual yield losses in both har vest and postharvest steps ( De Geyter et al., 2007a ). A pri mary way to achieve pest pre ven tion is to use chem i cal in sec ti cides by more than 2.5 mil lion tons per year which have their own con se quences, e.g., bio haz ards on non -target or gan isms, ben e fi cial in sects and en vi ron men tal pol lu tions ( USEPA, 2011 ;Da Silva et al., 2012 ). ...
... Growth and de vel op ment of in sects are highly in flu enced by Ecdys teroids in all life stages ( Koolman, 1989 ). Be cause in sects are not able to pro duce sterol struc tures, they re quire a kind of sterol in clud ing cho les terol or phy tos terols in their foods as pri mary com po nents for the biosyn the sis of ecdys teroids. Saponins may dis soci ate the in ter nal lin ing of ep ithe lial cells of the gut, form com plexes with sterols which are in di gestible, sup press up take of sterols and fail in sect molt ing by cel lu lar tox i c ity and ecdysial ab nor mal i ties ( Taylor et al., 2004 ) that the lat ter may oc cur due to their struc tural sim i lar ity with ecdys teroid hor mones of in sect ( De Geyter et al., 2007a ;Roopashree and Naik, 2019 ). Thus, these var i ous modes of ac tions and neg a tive im pact on in sects made saponins a great model of study to con trol pests like aphids, bee tles, wee vils, leafhop pers, worms and moths ( Singh and Kaur, 2018 ). ...
... So they must gain sterols from food. Saponins can bind to sterols and dis turb meta mor pho sis by in hibit ing the ab sorp tion of sterols ( Taylor et al., 2004 ;De Geyter et al., 2007a, Lam bert et al., 2007. Our re sults demon strated sig nif i cant dif fer ence in EcR ex pres sion be tween TSS -treated and con trol lar vae of H. armigera ( Fig. 3 ). ...
Article
Toxic effects of a saponin (TSS) from Camellia sinensis L. were investigated on mortality, nutrition, digestion and ecdysteroid receptors of Helicoverpa armigera Hubner through bioassay, biochemical assays and gene expression. Different concentrations of TSS were added to the artificial diet of the larvae to evaluate intended parameters. The LC50 of TSS was found 3.66% with a confidence limit of 3.07–4.51 at 95% although ingestion of sublethal concentration decreased nutritional indices including approximate digestibility, the efficiency of conversion of digested food, the efficiency of conversion of ingested food, relative growth rate, and relative consumption rate. These findings accompanied by the lower activities of digestive enzymes including carbohydrases, TAG-lipase, serine proteases and exopeptidases. Expression of the genes related to digestive enzymes demonstrated a significant decrease in the TSS-ingested larvae similar to biochemical experiment. Moreover, the gene expression of the ecdysteroid receptor in the TSS-treated larvae showed a significant difference compared to control. These results indicate the initial results on the toxicity of TSS against H. armigera and emboss its potential as a nature-origin insecticide.
... Nowadays, plant natural products have attracted much attention as a safe, effective, and environmentally friendly alternative to replace harmful conventional pesticides (Chaieb 2010;De Geyter et al. 2007;D'Incao et al. 2012;Pavela 2016). Many studies have reported that crude extracts or bioactive constituents from medicinal plants exert detrimental effects on survival, growth, and insect reproduction because of their toxic and deterrent activities (Chaieb 2010;De Geyter et al. 2011;Hussein et al. 2005;Saha et al. 2010). ...
... On the other hand, many saponin compounds elicit a reduction of the food intake for several insect species producing nutritive deficiency that can cause death or inhibit the evolution for next stage (Chaieb 2010;De Geyter et al. 2007;Dowd et al. 2011;Gao et al. 2010). Adel et al. (2000) suggested that the addition of saponins to artificial diet is the cause that sterols are not uptake in the intestine, causing low nutrient availability for the normal development and survival of the insect. ...
... Adel et al. (2000) suggested that the addition of saponins to artificial diet is the cause that sterols are not uptake in the intestine, causing low nutrient availability for the normal development and survival of the insect. Also, it has been suggested that saponins could interact with digestive enzymes forming a complex with them causing a decrease in enzyme digestive capabilities (De Geyter et al. 2007;Singh et al. 2017;Taylor et al. 2004). In this context, Pedersen et al. (1976) attributed the high resistance of six alfalfa cultivars against pea aphids to high contents of saponins. ...
Article
Hylurgus ligniperda is one of the most important quarantine forest insects associated to pine (Pinus radiate D. Don) logs exported from Chile. Methyl bromide fumigation has been the prominent control method. As the use of this synthetic insecticide leads to serious environmental problems, research to find alternative treatments is urgently needed for the Chilean forestry sector. Hence, plant secondary metabolites have been considered as an alternative for its control. Therefore, the objective of this work was to assess the feeding behavior of H. ligniperda through the artificial diet supplemented with organic fractions obtained from Cestrum parqui leaves. Organic extracts were obtained using a Soxhlet extraction. Non-choice tests were developed for testing the antifeedant activity shown by the organic fractions on adults, and 5th and 6th instar larvae of H. ligniperda. All the extracts tested elicited a decrease in the weight of unsexed H. ligniperda adults, and the effects were dose-dependent. Male beetle weight gain was reduced strongly by chloroform extracts and ethyl acetate elicited a weight increase of female and from the fifth and sixth instar larvae weight. Saponin extract elicited a reduction of the weight in male and female. Finally, the weight of both instar larvae was reduced by chloroform and saponin extract. C. parqui leaf extracts show a great potential for being used for controlling H. ligniperda and thus to diminish the use of harmful synthetic pesticide.
... This resistance to glucosinolates suggests that their lower preference and performance on the G-type is caused by its saponins and not by glucosinolates, as previously found for P. xylostella and P. nemorum. Several other studies have found negative effects of oleanane-type and hederagenin-based saponins on insect larval and adult performance, survival and reproduction (Adel et al. 2000;De Geyter et al. 2007;Dowd et al. 2011; Geyter et al. 2007;Goławska 2007). Interestingly, saponins may have extended effects on insect herbivores even after cessation of feeding (Adel et al. 2000), suggesting that the low initial performance of larvae on G-type leaves in our experiments may be magnified during subsequent life stages, as found for P. napi (see below). ...
... This resistance to glucosinolates suggests that their lower preference and performance on the G-type is caused by its saponins and not by glucosinolates, as previously found for P. xylostella and P. nemorum. Several other studies have found negative effects of oleanane-type and hederagenin-based saponins on insect larval and adult performance, survival and reproduction (Adel et al. 2000;De Geyter et al. 2007;Dowd et al. 2011; Geyter et al. 2007;Goławska 2007). Interestingly, saponins may have extended effects on insect herbivores even after cessation of feeding (Adel et al. 2000), suggesting that the low initial performance of larvae on G-type leaves in our experiments may be magnified during subsequent life stages, as found for P. napi (see below). ...
... Saponins are a class of secondary plant metabolites that includes triterpenoids, steroids, and steroidal alkaloids glycosylated with one or more sugar chains. Saponins in plants taste bitter, and they have been hypothesized to exert a repellent/deterrent activity, give rise to digestive problems, provoke molting defects, and exert toxic effects in insects (13)(14)(15)(16). Saponins are produced by many plant species. ...
... Tea saponin has desirable characters such as strong foaming, emulsifying, dispersing, and wetting performance (40,41), as well as anticancer (42), anti-inflammatory, antibacterial (42), and other biological activities (13), and it has been widely used as an insecticide in China (15). We herein demonstrated that there was a significant negative correlation between the body weight of CW larvae and tea saponin content in seeds during the same growth period (Fig. 2 and 3). ...
Article
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The gut microbiome may play an important role in insect-plant interactions mediated by plant secondary metabolites, but the microbial communities and functions of toxic plant feeders are still poorly characterized. In the present study, we provide the first metagenome of gut bacterial communities associated with a specialist weevil feeding on saponin-rich and saponin-low camellia seeds, and the results reveal the correlation between bacterial diversity and plant allelochemicals. We also used cultured microbes to establish their saponin-degradative capacity outside the insect. Our results provide new experimental context to better understand how gut microbial communities are influenced by plant secondary metabolites and how the resistance mechanisms involving microbes have evolved to deal with the chemical defenses of plants.
... These molecules have pesticide potential and are toxic to insects. Insecticidal activities include toxicity to harmful insects (antifeedants, disturbance of moulting, growth regulation and mortality) due to their interaction with cholesterol, causing a disturbance of the synthesis of ecdysteroids, which serves also as protease inhibitors or cytotoxic to insects as moulting and ecdysis are disturbed [201][202]. Saponins interfere with insects behavior, regulate growth and induced high toxicity on a vast array of arthropod pests and vectors such as Tetranychus urticae Koch, Spodoptera littoralis (Boisduval), Culex pipiens Linnaeus [203], caused growth inhibition, larvicidal capacity and mortality in caterpillars and aphids [42]. ...
... Saponins are toxic because of their ability to increase permeability abilities of plasma membranes, causing lysis of erythrocytes in vitro [204]. Thus, a high dose of saponin in the gut of an insect leads to disruption of the cell membrane and cell lysis of the intestinal mucosal cells [202]. Saponins which are glycocides with soapy characteristics are reported to possess bioactive agents due to their bitter and acrid taste resulting in feeding deterrents in the insects [200]. ...
Article
Full-text available
Bio-pesticides are biological derived agents that are usually applied in a manner similar to synthetic pesticides but achieve pest management in an environmental friendly way. Bioinsecticides have the advantages of been reportedly eco-friendly both to man and the environment, are target specific, lack problem of residue, least persistent in environment, locally available, easily processed and inexpensive, though with the limitation of requiring repeated applications for the achievement of optimal control of insect pests while enhancing crop protection. The mode of action of bioinsecticides on insects includes repellent action, antifeedant activity, oviposition deterrent properties, growth and development inhibition, toxicity, attractants, sterility and death. Hence, bioinsecticides can be included in integrated pest management programs for crop protection and insect pest control. The review on biopesticidal properties of some plant secondary metabolites in the leaves, stems, bark, fruits, flowers, cloves, rhizomes, grains and seeds of plants and their interference with the growth, feeding, reproduction of insect pestsfor pest management has been elaborated.
... The toxicity tested by incorporating luciamin in artificial diets resulted in a constant decrease in aphids' survival. The study's findings showed a clear deterrent impact of luciamins (500 mM) in wheat aphids and were the first spirostanic saponins recorded to have insecticidal efficacy (De Geyter et al., 2007b). Nielsen et al. (2010) reported a saponin playing a role in Barbarea vulgaris resistance against flea beetle (Phyllotreta nemorumi L.). ...
Article
Full-text available
Pulse beetle, Callosobruchus maculatus (Bruchidae: Coleoptera), commonly known as Cowpea weevil or Cowpea seed beetle is a pest of stored grain that attacks legumes in the field and stored conditions. An investigation was conducted for screening the developmental preference of Callosobruchus maculatus in different legumes. Five different legumes were used with three replications in Completely Randomized Design (CRD). The grains of legumes were obtained from the local market of Dera Ghazi Khan. Two pairs of adult (C. maculatus) were inoculated in 20 g seeds of different legumes. Statistics on egg count, egg-laying preference percentage, hatching percentage, incubation period, larval + pupal period, total developmental period (from egg to adult), male and female population, total adult emergence, No. of holes in seeds and seeds weight loss percentage was recorded. The outcomes of this study represented that red kidney bean grains (22.54%) contained more egg-laying preference for C. maculatus as compared to other tested legumes while desi chickpea grains (14.53%) had a lesser ovipositional preference. Minimum growth period was recorded on mung bean (22.66 days), followed by cowpea (24.33 days), kabuli chickpea (27 days) and desi chickpea (30.33 days). But there was (0.0 days) no growth of C. maculatus on red kidney bean grains. In short, smooth seed coat and well-filled seeds were most preferred by C. maculatus for egg-laying, short developmental time, maximum adult emergence and increased holed seeds.
... The toxicity tested by incorporating luciamin in artificial diets resulted in a constant decrease in aphids' survival. The study's findings showed a clear deterrent impact of luciamins (500 mM) in wheat aphids and were the first spirostanic saponins recorded to have insecticidal efficacy (De Geyter et al., 2007b). Nielsen et al. (2010) reported a saponin playing a role in Barbarea vulgaris resistance against flea beetle (Phyllotreta nemorumi L.). ...
Article
Microbial pathogens attack every plant tissue, including leaves, roots, shoots, and flowers during all growth stages. Thus, they cause several diseases resulting in a plant’s failure or loss of the whole crop in severe cases. To combat the pathogens attack, plants produce some biologically active toxic compounds known as saponins. The saponins are secondary metabolic compounds produced in healthy plants with potential anti-pathogenic activity and serve as potential chemical barriers against pathogens. Saponins are classified into two major groups the steroidal and terpenoid saponins. Here, we reported the significance of saponin toxins in the war against insect pests, fungal, and bacterial pathogens. Saponins are present in both cultivated (chilies, spinach, soybean, quinoa, onion, oat, tea, etc.) and wild plant species. As they are natural toxic constituents of plant defense, breeders and plant researchers aiming to boost plant immunity should focus on transferring these compounds in cash crops.
... While saponins can be structurally defined as a combination between an aglycone, or sapogenin unit, linked to one or more sugar chains at C3 (Fig. 10), the nature of the aglycone allows defining three groups of saponins: (1) saponins containing a steroidal aglycone, (2) saponins containing a triterpenoid aglycone, and (3) saponins containing an alkaloid aglycone [219]. Scientific literature reported that saponins exhibited a large spectrum of biological activities including antibacterial [220], antifungal [221], antiviral [222], insecticidal [223], anti-inflammatory [224], cytotoxic [225], and antiproliferative effect [226]. Saponins in O. ficus-indica need more investigations. ...
... [17][18][19][20][21] They are promising source of triterpenoids that are generally act by permeabilising cell membrane and in various stress conditions render protection against pathogens and pests. [22][23] ...
... In addition, plants have the ability to produce several insecticidal compounds to defend themselves. Chemical compounds like saponine, glucoside, ethylene and jasmonate are produced by corn plants against insect attacks (Geyter et al. 2007;Yan et al. 2012;Meihls et al. 2013;Louis et al. 2015). The low colonization of IAC 8046, SCS 156 Colorado and IAC 8390 by D. melacanthus suggests that few stimuli for the initiation of feeding are present and/or the presence of unpalatable compounds, which can affect stink bugs, such as Nezara viridula L. (Hemiptera: Pentatomidae) on soybean genotypes . ...
Article
Full-text available
Stink bugs are considered limiting pests to important crops worldwide. In Brazil, the green-belly stink bug, Dichelops melacanthus Dallas (Hemiptera: Pentatomidae), has become a key pest to the young phase of corn crop, being a problem especially when it succeeds soybean in the field. Injuries caused by this species vary from holes on new leaves to plant death in severe attacks. The main control technique used to this pest are seed treatment and insecticide spraying. Although both methods show some efficiency, factors as outbreaks in the resistance to insecticides and the different susceptibility existent among stink bugs population, leads to the search of other control strategies. Thus, less harmful tools to the environment and humans are highly desirable. In this sense, resistant plants appear as a valuable alternative for insect management, being compatible with other IPM methods. This study evaluated the resistance of 16 corn genotypes to D. melacanthus in order to characterize antixenosis and/or antibiosis expression. Antixenosis was accessed through preference multi-choice test with 5th instar nymphs. For antibiosis assessment, 60 2nd instar nymphs were confined on seedlings of 13 selected genotypes. Seedlings of IAC 8046, IAC 8390 and SCS 156 Colorado corn genotypes were less infested by D. melacanthus at 24 h after bugs were released indicating antixenosis expression. Genotypes IAC 8390 and JM 2M60 negatively affected some biological parameters of the green belly stink bug, indicating the occurrence of antibiosis. These genotypes can be useful to breeding programs focusing on corn resistance to stink bugs species.
... The latter aspect might explain the poor performance of larvae on diets B2, B4 and A4. These contained 26-39% of pea by-product (class II), which can hold saponins that exert phagodeterrent and insecticidal effects (De Geyter et al., 2007;Singha and Kaur, 2018;Taylor et al., 2004). ...
Article
Organic side-streams and agricultural wastes represent a big pool of untapped and underrated resources which could be efficiently exploited for insect rearing. We evaluated the suitability of eleven agricultural by-products, stemming from the production of cotton, sugar beet, sunflower, barley, oats, peas and vetch, for the development of larvae of the yellow mealworm, Tenebrio molitor. In a first bioassay, by-products were screened singly to evaluate their potential to support the development of middle sized (4th-6th instar) larvae. In a second bioassay, by-products were supplemented with carrot, and their potential to support complete larval development (first instar until first pupation) was evaluated. Lastly, a third bioassay was conducted in which the more promising by-products were used as components of isonitrogenous diets for middle sized larvae, at two nitrogen levels (2.7 and 3.2%). Our results show the suitability of several agricultural by-products from Greece for T. molitor larvae. The best results though were obtained with the oat and the barley by-product (class II), tested either singly or mixed in diets. These by-products can be utilised singly or in composed diets and can greatly decrease the feed costs of mealworm production. Moreover, the results obtained from the isonitrogenous diets bioassay, show that besides nitrogen content, other factors need to be considered when formulating optimal diets. Our study aims to implement circular economy practices in insect farming at a local level.
... Most alkaloids are toxic and function principally in protecting against microbial infection and plants attack by herbivores (Easwar et al., 2017). Saponins are reported to have prospective use as natural insecticides and they put forth a powerful and rapid-working action against a wide variety of pests (De Geyter et al., 2007). This finding proves that E. tirucalli could be propective source of pesticides. ...
Article
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This study investigated effect of Euphorbia tirucalli extracts on Daniellia oliveri and Ficus capensis woods. Wood samples were purchased and processed into 10 cm x 2 cm x 2 cm dimensions, while plant parts collected were oven dried before extraction. E. tirucalli was screened for phytochemicals. Concentrations of 0.5%, 1% and 2% extracts were prepared by serial dilution. Soligum, methanol and untreated wood samples were used as control. Treated wood samples were laid within 6 x 12 metres field at 1 x 3 metres spacing in a Completely Randomized Design (CRD) in a termitarium and data were taken within 8 weeks. Phytochemical results indicated the presence of alkaloids, phenols, tannins, cardiac glycosides, flavonoids and saponins. Percentage absorption of extracts ranged from 47-86 % and 94.00-50.67 % in D. oliveri and F. capensis, respectively. Percentage retention of extracts ranged from 10.84-2.14 kg/m 3 and 11.62-7.01 kg/m 3 in D. oliveri and F. capensis. Soligum treated wood samples were not attacked throughout the period of study. D. oliveri and F. capensis woods treated with 0.5% E. tirucalli methanol extract were not attached on till the 6 th and 8 th week respectively. The least percentage weight loss of 5.49 % and 28.32 % were recorded for D. oliveri and F. capensis woods treated with soligum, while, 27.5 5 % and 52.50 % weight loss were recorded for F. capensis and D. oliveri woods treated with 0.5% methanol extract. It was concluded that the use of E. tirucalli extracts could be exploited to develop new wood presevatives to protect wood and wood products.
... One of the major causes of crop losses is phytophagous insect species (Isman 2000). Insect infestation has a direct impact on agricultural food production and stored products as they may account for 20-30% production loss and in severe cases, they cause total loss (De Geyter et al. 2007). Aphids can cause damage to hundreds of host plants in both the field and under protection (Mardani-Talaee et al. 2016), by sucking plant sap, transmitting plant viruses, and excreting honeydew that induces fungal growth (Sprawka et al. 2011). ...
Article
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The insecticidal potential of the Saharan plant Cotula cinerea, was evaluated on two insect species namely Aphis fabae and Tribolium castaneum by topical application (contact toxicity) and repellency test. A crude ethanolic extract of aerial part of the plant was prepared and tested in the laboratory on adults of both species. For contact toxicity, five doses were tested on each of the two species 1.56, 3.12, 6.25, 12.5 and 25 mg/ml for A. fabae and 25, 50, 250, 350 and 500 µg/insect for T. castaneum. The repellency of the extract was studied at the dose 500 μg/insect for T. castaneum and 25 µg/ml for A. fabae. Results showed that the repellency of the extract increased with exposure time and the highest rates were observed after 4 h of exposure (72.33 ± 22% for T. castaneum and 87 ± 3.6% for A. fabae). For insecticidal activity, at the highest doses (25 mg/ml and 500 µg/ml), 100% mortality is obtained 72 h after treatment for A. fabae and after 48 h for T. castaneum. The extract of this plant was found to be more toxic against T. castaneum adults. LD50 calculated 24 h after treatment for the two species is estimated at 1.7 mg/ml for A. fabae and at 30.3 µg/insect for T. castaneum. The extract of this plant inhibited the activity of acetylcholinesterase (AChE) in both insect species. This result suggests that this plant has a neurotoxic effect on A. fabae and T. castaneum. The results of phytochemical study showed that the plant is mainly rich in flavonoids, gallic tannins, alkaloids, saponosides and glucosides. The insecticidal effect obtained in this study could be due to the synergetic action of all constituents of the extract. Results suggest the possibility of using the extracts of this plant in integrated pest management to replace the chemical insecticides.
... 19 Triterpenoid saponins have been investigated for botanic insecticides to prevent various agricultural pests such as aphids and leafhoppers (Hemipterans), beetles and weevils (Coleopetrans), as well as leafworms and moths (Lepidopterans) in fields. 20,21 This provides a new strategy for the development of plant-derived insecticides for the affluent triterpenoid saponins from Clematis. ...
Article
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BACKGROUND The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a global insect pest of crops, leading to a reduction of agricultural products in productivity and quality. Plant saponins are rich sources for the discovery of candidates to control of insect pests. This study focused on discovery of triterpenoid saponins from Clematis aethusifolia Turcz and evaluation of their antifeedant, insecticidal and insect growth inhibitory activities against the 3rd instar larvae of P. xylostella. RESULTS Seven triterpenoid saponins (1–7 ) were isolated for the first time from the n ‐BuOH extract of C. aethusifolia . Monodesmosides 1 , 2 , and 5 with a free 28‐COOH group showed much higher antifeedant activity (DC50 were 733.67−844.77 μg/mL at 24 h, and 737.19−748.28 μg/mL at 48 h) than bidesmosides 3−4 and 6−7 (DC50 were 1284.35−2053.98 μg/mL at 24 h, and 1183.72−1990.96 μg/mL at 48 h). Similarly, monodesmosides 1 , 2 , and 5 (LC50 were 1462.78− 1785.96 μg/mL) showed stronger insecticidal activity than bidesmosides 3−4 and 6−7 (LC50 were 2219.22− 3050.51 μg/mL) against P. xylostella at 72 h. These results suggest the 28‐COOH group is an important functional group for their antifeedant and insecticidal activity. Besides, monodesmosides 1 , 2 , and 5 showed insect growth inhibitory activity against P. xylostella through reduction of larval growth and percentage of pupation, associated with prolongation of larval and pupal stages. CONCLUSION The present results provide evidence that triterpenoid saponins from C. aethusifolia , particularly those monodesmosides saponins with a free 28‐COOH group have the potential to be developed as pesticides to control of P. xylostella . This article is protected by copyright. All rights reserved.
... A study byCeja-Navarro et al. (2015) demonstrated that this is possible because of the association with Pseudomonas bacteria that detoxify caffeine by expressing caffeine demethylase genes. Saponins are another type of plant secondary metabolite with insecticidal activity(De Geyter, Lambert, Geelen, & Smagghe, 2007). Plants from the genus Camellia, the leaves of which may be consumed as tea, contain high levels of saponins both the leaves and the seeds. ...
Article
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The weevil superfamily Curculionoidea is the largest insect group and so the largest animal group on Earth. This taxon includes species which represent an important threat to many economically important crops and, therefore, pose a risk to agriculture and food security. Insect‐bacteria associations have been recognised to provide the insect host with many benefits, such as ensuring the acquisition of essential nutrients or protecting the host from natural enemies. The role of bacteria associations within the weevil superfamily remains nonetheless understudied in comparison with other insect taxa. This review draws together existing knowledge on the influence of bacteria associated with weevils known to be agricultural pest species. The implications of these weevil‐bacterial associations in determining pest status and their relevance to targeted pest management interventions is discussed. Specific consideration is given to the role of bacteria in cuticle formation, flight activity, reproduction manipulation and adaptation to different environments and food sources.
... The result obtained on the phytochemical constituents of the ethanolic extracts of the tested plants revealed the presence of alkaloids, saponins, tannins, flavonoids, and cardiac glycosides. Secondary metabolites such as phenolic compounds, saponins, alkaloids, flavonoids, and terpenoids have been identified to exhibit strong activities against several pathogens and insect pests (De Geyter et al., 2007). Acanthus montanus was the most toxic to maize weevil, it had the highest composition of alkaloid, saponin, tannin and flavonoid compare to other experimental plants. ...
Article
Toxicities of leaf powders and extracts of Acanthus montanus, Acanthospermum hispidum, Alchornea laxiflora and Argyreia nervosa against maize weevil (Sitophilus zeamais) were evaluated. Powders were tested at dose 3.0g/20g while extracts were tested at concentration 3%/20g of maize grains. Mortality, oviposition, and adult emergence rates as well as weight loss, seeds damage and weevil perforation index (WPI) were evaluated. Phytochemical constituents of the experimental plants were also carried out. The results showed that Acanthus montanus powder was the most potent with 65% adult mortality after 24 h of treatment. This is followed by Argyreia nervosa powder that evoked 52.5% weevil mortality. The least toxic to S. zeamais was Acanthospermum hispidum powder with 32.5% adult mortality. Extracts were more toxic than the powders of the tested plants. Acanthus montanus extract was the most toxic since it promoted 80% adult mortality after 24 h of treatment. Acanthus montanus, Alchornea laxiflora and Argyreia nervosa leaf powders and extracts completely prevented oviposition by adult insect, adult emergence, weight loss and seeds damaged. The phytochemicals present in Acanthus montanus were alkaloids (3.67 mg/g), saponin (3.33 mg/g), tannin (3.00 mg/g) and flavonoid (2.67 mg/g) contents. Acanthospermum hispidum had the least alkaloid (2.67 mg/g), saponin (1.67 mg/g), tannin (1.33 mg/g) and flavonoid (1.00 mg/g) contents. Acanthus montanus, Argyreia nervosa, Alchornea laxiflora and Acanthospermum hispidum were efficacious against S. zeamais instead of synthetic chemical insecticides that have environmental health hazards and they can be used in integrated pest management by farmers and foods merchants.
... Distribution A wide variety of crops and edible plants contains different compounds from the saponins Triterpenoid saponins have been detected in many plants such as soybeans, beans, peas, tea, spinach, sugar beet, quinoa, citrus etc. Steroidal saponins are found in oats, tomato seed, asparagus, eggplant, etc. (Table 1). Cereals and grasses appear to be generally deficient in saponins, although there is still some exception, for example, oats, switchgrass, and kleingrass (De Geyter et al., 2007). The concentration of saponins found in barley husk were significantly higher (1.96 mg/g) than in wheat bran (1.16 mg/g). ...
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Saponins are an important group of plant secondary metabolites that are widely distributed throughout the plant kingdom. These biomolecules can be divided into two main classes represented by triterpenoid and steroid glycosides whose structure varies according to the number of sugar units attached in different positions. Despite saponins have been historically considered as anti-nutritional factors, recent studies have indicated that some saponin stereoisomers may show a number of pharmacological activities, such as anti-tumor, antioxidative, anti-inflammatory, antidiabetic, and neuro-protective activities. Nerveless, more attention in studying this group is necessary due to the fact that many active mechanisms are not fully elucidated. To have a systematic overview of saponin compounds, this review will describe the main aspects related to their structure, bioactivities and potential applications.
... We believe that plants, like Pisonia aculeata and G. ulmifolia that attracted the CAL when used as source of odor but were not consumed when used as source of food, might contain antinutritional or toxic compounds. In this regard, related species to Pisonia aculeata have high content of saponins in their leaves, compounds that are considered antifeedant, molt disturbant, growth regulator, and toxic (Lavaud et al 1996, De Feo et al 1998, De Geyter et al 2007, Chaieb 2010. Similarly, in G. ulmifolia, precocene I, a major chemical constituent of leaves, is a toxic compound that causes changes in physiology and morphology of insects (Arriaga et al 1997, Farazmand & Chaika 2011. ...
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The Central American Locust (CAL) Schistocerca piceifrons piceifrons Walker is one of the most harmful plant pests in the Yucatan Peninsula, where an important gregarious zone is located. The attraction and host plant acceptance by the CAL have not been studied in detail thus far. In this work, the CAL attraction to various plant species was evaluated using an olfactometer test system, and the host plant acceptance was assessed by the consumption of leaf area. Results showed that the CAL was highly attracted to Pisonia aculeata. Evaluation of host plant acceptance showed that the CAL fed on Leucaena glauca and Waltheria americana, but not on P. aculeata or Guazuma ulmifolia. Analysis of leaf thickness, and leaf content of nitrogen (N) and carbon (C) showed that the CAL was attracted to plant species with low leaf C content.
... One of the major causes of crop losses is phytophagous insect species (Isman 2000). Insect infestation has a direct impact on agricultural food production and stored products as they may account for 20-30% production loss and in severe cases, they cause total loss (De Geyter et al. 2007). Aphids can cause damage to hundreds of host plants in both the field and under protection (Mardani-Talaee et al. 2016), by sucking plant sap, transmitting plant viruses, and excreting honeydew that induces fungal growth (Sprawka et al. 2011). ...
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A., Belaid, M., Baouche, N., and Bouazouz, H. 2020. Potentials of the extracts of Algerian Saharan plant Cotula cinerea for the management of two insect pests, Aphis fabae and Tribolium castaneum. Tunisian Journal of Plant Protection 15 (2): 41-57. The insecticidal potential of the Saharan plant Cotula cinerea, was evaluated on two insect species namely Aphis fabae and Tribolium castaneum by topical application (contact toxicity) and repellency test. A crude ethanolic extract of aerial part of the plant was prepared and tested in the laboratory on adults of both species. For contact toxicity, five doses were tested on each of the two species 1.56, 3.12, 6.25, 12.5 and 25 mg/ml for A. fabae and 25, 50, 250, 350 and 500 µg/insect for T. castaneum. The repellency of the extract was studied at the dose 500 μg/insect for T. castaneum and 25 µg/ml for A. fabae. Results showed that the repellency of the extract increased with exposure time and the highest rates were observed after 4 h of exposure (72.33 ± 22% for T. castaneum and 87 ± 3.6% for A. fabae). For insecticidal activity, at the highest doses (25 mg/ml and 500 µg/ml), 100% mortality is obtained 72 h after treatment for A. fabae and after 48 h for T. castaneum. The extract of this plant was found to be more toxic against T. castaneum adults. LD50 calculated 24 h after treatment for the two species is estimated at 1.7 mg/ml for A. fabae and at 30.3 µg/insect for T. castaneum. The extract of this plant inhibited the activity of acetylcholinesterase (AChE) in both insect species. This result suggests that this plant has a neurotoxic effect on A. fabae and T. castaneum. The results of phytochemical study showed that the plant is mainly rich in flavonoids, gallic tannins, alkaloids, saponosides and glucosides. The insecticidal effect obtained in this study could be due to the synergetic action of all constituents of the extract. Results suggest the possibility of using the extracts of this plant in integrated pest management to replace the chemical insecticides.
... In deserts, the shrubs of the genus Acaciacontain contain high concentrations of saponins in seed pods in order to prevent birds from eating the seeds. Fruits of Sapindus mukorossi, leaves of Cestrum nocturnm, C. diurnum and Asclepias curassavica are rich sources of saponins that can be used as mosquito larvicide [101]. Table 3. Different plant species with common volatile terpenes released in response to insects' attack. ...
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In this review, we describe the role of plant-derived biochemicals that are toxic to insect pests. Biotic stress in plants caused by insect pests is one of the most significant problems, leading to yield losses. Synthetic pesticides still play a significant role in crop protection. However, the environmental side effects and health issues caused by the overuse or inappropriate application of synthetic pesticides forced authorities to ban some problematic ones. Consequently, there is a strong necessity for novel and alternative insect pest control methods. An interesting source of ecological pesticides are biocidal compounds, naturally occurring in plants as allelochemicals (secondary metabolites), helping plants to resist, tolerate or compensate the stress caused by insect pests. The abovementioned bioactive natural products are the first line of defense in plants against insect herbivores. The large group of secondary plant metabolites, including alkaloids, saponins, phenols and terpenes, are the most promising compounds in the management of insect pests. Secondary metabolites offer sustainable pest control, therefore we can conclude that certain plant species provide numerous promising possibilities for discovering novel and ecologically friendly methods for the control of numerous insect pests.
... They can cause 20-30% production losses and in severe cases, total yield loss. Insects damage field crops by sucking, chewing or boring into different parts of the plants. Considering damage to stored products, they directly feed, bore and ruin grains and accelerate the process of decay (de Geyter et al. 2007;Mills 2014). Moreover, as climate warming advances, insect pests are predicted to substantially impact crop production, since higher temperatures increase their metabolic rate, increasing, consequently, their nutrient consumption and population growth rate (Deutsch et al. 2018). ...
Chapter
During its history, humankind has been affected by three factors: food deficiency, health problems, and environmental issues. With world’s population increasing at a high rate, our requirement for food is increasing. Consequently, agricultural practices that maximize crop productivity are necessary. These include the development of new agronomic technologies and new plant varieties, the use of fertilizers, pesticides and herbicides, in order to minimize losses due to plant predators and weeds, respectively. Thus, a continued need for pest management in agriculture became evident, with pressure to efficiently produce more food using less land. To solve this issue, conventional chemical pesticides have been widely used in agriculture despite presenting risks to human health, hazards to the environment as well as affecting non-target species. Therefore, the use of biopesticides is desired due to their target specificity and low environmental damage. They encompass different types of molecules, usually produced by microbial biosynthesis, and are widely used for pest control. Biocontrol, which depends on microorganisms or their products such as hydrolytic enzymes, became a promising alternative to conventional pest control. Microbial hydrolytic enzymes such as proteases, chitinases, lipases, and glucanases are attractive for this purpose, since they present toxic properties, acting synergistically to control pest attacks. Proteases act on the insect cuticles, since proteins constitute the majority of this structure. These enzymes also can act in the insect midgut and hemocoel. Proteases can also be used in the biological control of other noxious agents, such as bacteria, fungi, and nematodes. Chitinases can degrade the peritrophic matrix and cuticle of insects, as well as the fungal cell wall. Lipases hydrolyze lipoproteins, waxes and fats present in the insect integument, causing its disruption. Glucanases affect fungal cell wall development, differentiation, and mycoparasitism, because glucan is a major cell wall component. In this chapter we cover details about enzymes structure, biochemistry, mechanisms of action, applications, and perspectives in this field.
... Scientific literature reported that saponins exhibited a large spectrum of biological activities including antibacterial [220], antifungal [221], antiviral [222], insecticidal [223], anti-inflammatory [224], cytotoxic [225], and antiproliferative effect [226]. Saponins in O. ficus-indica need more investigations. ...
... For example, the group B saponins were found to be one of the key secondary metabolites that conferred salt tolerance in soybean, making saponins important secondary metabolites in soybean (Wu et al., 2008). The anti-herbivory properties of saponins make them natural insect repellents that protect the plant from biotic threats (De Geyter, Lambert, Geelen, & Smagghe, 2007). ...
Chapter
Soybean is a food crop in high demand in Northeast Asia. Besides protein and oil, soybean is also a rich source of health-beneficial secondary metabolites such as flavonoids, terpenes, and alkaloids. The long history of soybean domestication resulted in a rich collection of soybean germplasms, which could be generally categorized as wild, landrace, and cultivated soybeans. Previous research has shown that soybean seeds from diverse genetic backgrounds exhibited different metabolite profiles. Germplasms originating from different geographical regions, i.e., at different latitudes and longitudes, probably experienced different selective pressures and evolved different secondary metabolite profiles. Domestication has generally led to a reduction in secondary metabolite contents in seeds since many of these compounds are related to the bitter taste or other agronomic traits that may hinder the ease of farming and harvest. These selection forces have possibly rendered the different flavors of soybean germplasms. Due to the popularity of soy food products, the post-domestication selection of soybean based on flavor is a common phenomenon. In Northeast Asian countries, soy foods such as soy milk, tofu, and fermented soy products are popular. Based on the consumer preference for the flavors of these products, soybean germplasms with different metabolite profiles are selected for different commercial uses. However, the breeding of soybeans for maximizing health benefits and for the preferred flavors of food products may create contradictions. Industrial methods to remove undesirable flavors and molecular breeding to produce cultivars with desired metabolite profiles may be the solution.
... Saponins possess foaming, pharmacological, medicinal, and hemolytic properties and also find a place in cosmetic, beverage, and confectionery industries (Kajal and Singh 2017). Medicinal properties include hemolytic factor (Hassan et al. 2010), anti-inflammatory (Just et al. 1998), antibacterial (Sparg et al. 2004), antifungal (Sindambiwe et al. 1998), antiviral (Simões et al. 1999), insecticidal (De-Geyter et al. 2007), anticancer (Cheng et al. 2011), cytotoxic (Mbaveng et al. 2018) and molluscicidal (Abdel-Gawad et al. 1999) action. In pharmaceutical industry, saponins are widely considered as precursors for the synthesis of steroidal drugs (Waheed et al. 2012). ...
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Saponins are the naturally occurring phytochemicals present in most vegetables, edible legumes, and herbs. These constitute a chemically diverse group of compounds that contain steroid or triterpenoid aglycone linked to one or more oligosaccharide moieties. These compounds are characterized by surface-active foaming properties, bitter taste, and astringency. Numerous studies have suggested the positive health benefits of saponins on blood cholesterol levels, bone health, blood glucose level, and cancer risk. A diet rich in saponins has been shown to reduce dental caries, inhibit platelet aggregation, treat hypercalciuria, and act as an antidote against heavy metal poisoning. The present review summarizes the phytochemistry and pharmacology of saponins derived from edible legumes and also highlights their positive health benefits.
... The reduction of parasitism in treated fruits possibly happened because of the strong odors released by the extract, since the female parasitoids guide themselves by olfactory stimuli while seeking the host [21]. So, such smell could act as a repellent, considering that some compounds found in A. sisalana can work as so. A. sisalana presents tannin, alkaloids, saponin and coumarin, and some of them act as repellent for some insects [22,23,24,19]. The volatiles released by the A. sisalana extract, in this case, can interfere in the chemical compounds naturally released by the fruits. ...
... Although plant biomass, shoot-to-root ratio and total phenolics in leaves were not affected (Fig. 1a-c), the saponins in both leaves and roots were significantly higher in the VOC-exposed plants (Fig. 1e,f). Saponins are well known as defense substances against various herbivore species including Spodoptera litura that are major herbivores of soybean 26,38 . Our results are consistent with those of Shiojiri et al. 11 who showed that the VOCs from cut goldenrod increase the defense of soybean plants against the herbivore, S. litura. ...
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Aboveground communication between plants is well known to change defense traits in leaves, but its effects on belowground plant traits and soil characteristics have not been elucidated. We hypothesized that aboveground plant-to-plant communication reduces root nodule symbiosis via induction of bactericidal chemical defense substances and changes the soil nutrient environment. Soybean plants were exposed to the volatile organic compounds (VOCs) from damaged shoots of Solidago canadensi s var. scabra , and leaf defense traits (total phenolics, saponins), root saponins, and root nodule symbiosis traits (number and biomass of root nodules) were measured. Soil C/N ratios and mineral concentrations were also measured to estimate the effects of resource uptake by the plants. We found that total phenolics were not affected. However, plants that received VOCs had higher saponin concentrations in both leaves and roots, and fewer root nodules than untreated plants. Although the concentrations of soil minerals did not differ between treatments, soil C/N ratio was significantly higher in the soil of communicated plants. Thus, the aboveground plant-to-plant communication led to reductions in root nodule symbiosis and soil nutrient concentrations. Our results suggest that there are broader effects of induced chemical defenses in aboveground plant organs upon belowground microbial interactions and soil nutrients, and emphasize that plant response based on plant-to-plant communications are a bridge between above- and below-ground ecosystems.
... Numerous studies have revealed that the haemolytic properties of saponin affect biological activities, thus, making it highly toxic to most coldblooded pests. In snails, it causes apoptosis, which leads to uncontrolled cell death (De Geyter et al., 2007;Sparg et al., 2004). Phaleria macrocarpa also known as mahkota dewa or God's crown, it is a medicinal plant indigenous to Indonesia and Malaysia. ...
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Apple snail is one of the major pest of rice crop and saponin proved to be the most promising bioactive compound to control it. This study was carried out to quantify saponin from God's Crown, Phaleria macrocarpa and to evaluate its efficacy against the biological activities of black apple snail, Pomacea maculata. Fruits, leaves and stem-barks of P. macrocarpa were quantified for saponin using HPLC. The toxicity of leaf and fruit crude extracts was evaluated through mortality and feeding deterrent bioassays using complete randomized design and data were analyzed by ANOVA for LSD test. The highest saponin contents 24.67 ppm was detected in fruits followed by 22.67 ppm in leaves and 5.94 ppm in stem-bark. Bioassays showed the highest mortality percentage (44%) after 24 hours exposure at the concentration of 1000 ppm of a leaf extract followed by 36% and 28% @ 750 and 1000 ppm of leaf and fruit extracts, respectively. After the exposure of 48 hours, mortality percentage increased to 100% @ 1000 and 750 ppm of both crude extracts while the mortality percentage recorded at the concentration of 500 ppm of leaves and fruits were 56% and 52% respectively. Mortality percentage at the concentration of 500 ppm was increased to 80% and 68% in leaf and fruit extracts after exposure of 72 hours, respectively. In terms of feeding deterrent, 1000, 750 and 500 ppm concentration of both crude extracts were not significantly different from the positive control niclosamide (p>0.05). The results obtained from the study revealed that saponin extracted from fruits and leaves of P. macrocarpa has a potential to control black apple snails.
... Moreover, the course of changes in their NO production was almost zero in the range of the tested concentrations, similar to the activities of mutually related phytoecdysteroids [32] tested previously [8]. Various other activities of Allium saponins described in [1,2] are involved in various concepts [33,34], especially in the plant defence against insect pests [35][36][37] or against a series of fungi pathogens [38][39][40], confirming their relevant chemo-ecological role [3,12,15]. ...
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Saponins, a diverse group of natural compounds, offer an interesting pool of derivatives with biomedical application. In this study, three structurally related spirostanol saponins were isolated and identified from the leek flowers of Allium porrum L. (garden leek). Two of them were identical with the already known leek plant constituents: aginoside (1) and 6-deoxyaginoside (2). The third one was identified as new component of A. porrum; however, it was found identical with yayoisaponin A (3) obtained earlier from a mutant of elephant garlic Allium ampeloprasun L. It is a derivative of the aginoside (1) with additional glucose in its glycosidic chain, identified by MS and NMR analysis as (2α, 3β, 6β, 25R)-2,6-dihydroxyspirostan-3-yl β-D-glucopyranosyl-(1 → 3)-β-D-glucopranosyl-(1 → 2)-[β-D-xylopyranosyl-(1 → 3)]-β-D-glucopyranosyl]-(1 → 4)-β-D-galactopyranoside, previously reported also under the name alliporin. The leek native saponins were tested together with other known and structurally related saponins (tomatonin and digitonin) and with their related aglycones (agigenin and diosgenin) for in vitro cytotoxicity and for effects on NO production in mouse peritoneal cells. The highest inhibitory effects were exhibited by 6-deoxyaginoside. The obtained toxicity data, however, closely correlated with the suppression of NO production. Therefore, an unambiguous linking of obtained bioactivities of saponins with their expected immunobiological properties remained uncertain.
... One of the major causes of crop losses is phytophagous insect species (Isman 2000). Insect infestation has a direct impact on agricultural food production and stored products as they may account for 20-30% production loss and in severe cases, they cause total loss (De Geyter et al. 2007). Aphids can cause damage to hundreds of host plants in both the field and under protection (Mardani-Talaee et al. 2016), by sucking plant sap, transmitting plant viruses, and excreting honeydew that induces fungal growth (Sprawka et al. 2011). ...
Article
Full-text available
The insecticidal potential of the Saharan plant Cotula cinerea, was evaluated on two insect species namely Aphis fabae and Tribolium castaneum by topical application (contact toxicity) and repellency test. A crude ethanolic extract of aerial part of the plant was prepared and tested in the laboratory on adults of both species. For contact toxicity, five doses were tested on each of the two species 1.56, 3.12, 6.25, 12.5 and 25 mg/ml for A. fabae and 25, 50, 250, 350 and 500 µg/insect for T. castaneum. The repellency of the extract was studied at the dose 500 μg/insect for T. castaneum and 25 µg/ml for A. fabae. Results showed that the repellency of the extract increased with exposure time and the highest rates were observed after 4 h of exposure (72.33 ± 22% for T. castaneum and 87 ± 3.6% for A. fabae). For insecticidal activity, at the highest doses (25 mg/ml and 500 µg/ml), 100% mortality is obtained 72h after treatment for A. fabae and after 48 h for T. castaneum. The extract of this plant was found to be more toxic against T. castaneum adults. LD50 alculated 24 h after treatment for the two species is estimated at 1.7 mg/ml for A. fabae and at 30.3 µg/insect for T. castaneum. The extract of this plant inhibited the activity of acetylcholinesterase (AChE) in both insect species. This result suggests that this plant has a neurotoxic effect on A. fabae and T. castaneum. The results of phytochemical study showed that the plant is mainly rich in flavonoids, gallic tannins, alkaloids, saponosides and glucosides. The insecticidal effect obtained in this study could be due to the synergetic action of all constituents of the extract. Results suggest the possibility of using the extracts of this plant in integrated pest management to replace the chemical insecticides
... Saponins are among those secondary plant compounds. They may be steroidal or triterpenoidal in nature and are characterized by a wide range of bioactivities (De Geyter et al., 2007). They possess strong surface-active properties that are responsible for many biological effects such as hemolytic activity, nutrient transportation and membrane permeability (Lavine and Strand, 2002). ...
... Due to their properties, hemolytic saponins from Medicago spp. are valuable specialized metabolites to be employed in the agro-industry and for pharmaceutical applications (Ellen et al., 2007;Bora and Sharma, 2011;Rafińska et al., 2017). ...
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In the Medicago genus, triterpene saponins are a group of bioactive compounds extensively studied for their different biological and pharmaceutical properties. In this work, the CRISPR/Cas9-based approach with two single-site guide RNAs was used in Medicago truncatula (barrel medic) to knock-out the CYP93E2 and CYP72A61 genes, which are responsible for the biosynthesis of soyasapogenol B, the most abundant soyasapogenol in Medicago spp. No transgenic plants carrying mutations in the target CYP72A61 gene were recovered while fifty-two putative CYP93E2 mutant plant lines were obtained following Agrobacterium tumefaciens-mediated transformation. Among these, the fifty-one sequenced plant lines give an editing efficiency of 84%. Sequencing revealed that these lines had various mutation patterns at the target sites. Four T0 mutant plant lines were further selected and examined for their sapogenin content and plant growth performance under greenhouse conditions. The results showed that all tested CYP93E2 knock-out mutants did not produce soyasapogenols in the leaves, stems and roots, and diverted the metabolic flux toward the production of valuable hemolytic sapogenins. No adverse influence was observed on the plant morphological features of CYP93E2 mutants under greenhouse conditions. In addition, differential expression of saponin pathway genes was observed in CYP93E2 mutants in comparison to the control. Our results provide new and interesting insights into the application of CRISPR/Cas9 for metabolic engineering of high-value compounds of plant origin and will be useful to investigate the physiological functions of saponins in planta.
... Ishaaya [49] suggested that they slow down the passage of food through the gut, whereas Shaney et al. [50] suggested that saponins block the uptake of sterols, an essential compound that insects cannot synthesize but have to take up through feeding. De Geijter et al. [51] reviewed the effects of saponins on insect herbivores and concluded, "These interesting plant compounds offer new strategies to protect crops in modern agriculture and horticulture with integrated pest management (IPM) programs against pest insects, either by spraying or by selecting high-saponin varieties of commercial crops." ...
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Understanding the mechanisms involved in host plant resistance opens the way for improved resistance breeding programs by using the traits involved as markers. Pest management is a major problem in cultivation of ornamentals. Gladiolus (Gladiolus hybridus L.) is an economically important ornamental in the Netherlands. Gladiolus is especially sensitive to attack by western flower thrips (Frankliniella occidentalis (Pergande) (Thysanoptera:Thripidae)). The objective of this study was, therefore, to investigate morphological and chemical markers for resistance breeding to western flower thrips in Gladiolus varieties. We measured thrips damage of 14 Gladiolus varieties in a whole-plant thrips bioassay and related this to morphological traits with a focus on papillae density. Moreover, we studied chemical host plant resistance to using an eco-metabolomic approach comparing the 1H NMR profiles of thrips resistant and susceptible varieties representing a broad range of papillae densities. Thrips damage varied strongly among varieties: the most susceptible variety showed 130 times more damage than the most resistant one. Varieties with low thrips damage had shorter mesophylls and epidermal cells, as well as a higher density of epicuticular papillae. All three traits related to thrips damage were highly correlated with each other. We observed a number of metabolites related to resistance against thrips: two unidentified triterpenoid saponins and the amino acids alanine and threonine. All these compounds were highly correlated amongst each other as well as to the density of papillae. These correlations suggest that papillae are involved in resistance to thrips by producing and/or storing compounds causing thrips resistance. Although it is not possible to distinguish the individual effects of morphological and chemical traits statistically, our results show that papillae density is an easy marker in Gladiolus-breeding programs targeted at increased resistance to thrips.
... Saponins are glycosides with a triterpenoid or steroidal nucleus, having deterrent and toxic effects on insects (De Geyter et al. 2007;Chaieb 2010). Tannins are phenolic polymers that bind strongly with proteins and may be toxic due to oxidative stress they cause on herbivores (Salminen and Karonen 2011;Barbehenn and Constabel 2011). ...
Article
Propolis is a honey bee product containing chiefly beeswax and resins originated from plant buds or exudates. Propolis resin exerts a diversity of biological activities, such as antitumoral, anti-inflammatory, antimicrobial, and defense of the hive against pathogens. Chemical standardization and identification of botanical sources is crucial for characterization of propolis. Types of Brazilian propolis are characteristic of geographical regions and respective biomes, such as savannas (Cerrado), mangroves, dry forest (Caatinga), rain forests (Amazon, Atlantic, and Interior forests), altitudinal fields (“Campos Rupestres”), Pantanal, and Araucaria forests. Despite the wide diversity of Brazilian biomes and flora, relatively few types of Brazilian propolis and corresponding resin plant sources have been reported. Factors accounting for the restricted number of known types of Brazilian propolis and plant sources are tentatively pointed out. Among them, the paper discusses constraints that honey bees must overcome to collect plant exudates, including the characteristics of the lapping-chewing mouthpart of honey bee, which limit their possibilities to cut and chew plant tissues, as well as chemical requirements that plant resins must fulfil, involving antimicrobial activity of its constituents and innocuity to the insects. Although much still needs to be done toward a more comprehensive picture of Brazilian propolis types and corresponding plant origins, the prospects indicate that the actual diversity of plant sources of honey bee propolis will remain relatively low.
... Insect herbivory is a crucial factor in yield loss and quality degradation in agricultural crop production. Average losses can reach 20-30% of yield, and in some cases, they can cause a total yield loss [2]. One of the most economically significant herbivores is found in the aphid family (Hemiptera: Aphididae) [3], a piercingsucking pest that feeds on the phloem sap. ...
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Background: Young wheat plants are continuously exposed to herbivorous insect attack. To reduce insect damage and maintain their growth, plants evolved different defense mechanisms, including the biosynthesis of deterrent compounds named benzoxazinoids, and/or trichome formation that provides physical barriers. It is unclear whether both of these mechanisms are equally critical in providing an efficient defense for wheat seedlings against aphids—an economically costly pest in cereal production. Results: In this study, we compared the transcriptome, metabolome, benzoxazinoids, and trichome density of three selected wheat genotypes, with a focus on differences related to defense mechanisms. We chose diverse wheat genotypes: two tetraploid wheat genotypes, domesticated durum ‘Svevo’ and wild emmer ‘Zavitan,’ and one hexaploid bread wheat, ‘Chinese Spring.’ The full transcriptomic analysis revealed a major difference between the three genotypes, while the clustering of significantly different genes suggested a higher similarity between the two domesticated wheats than between either and the wild wheat. A pathway enrichment analysis indicated that the genes associated with primary metabolism, as well as the pathways associated with defense such as phytohormones and specialized metabolites, were different between the three genotypes. Measurement of benzoxazinoid levels at the three time points (11, 15, and 18 days after germination) revealed high levels in the two domesticated genotypes, while in wild emmer wheat, they were below detection level. In contrast to the benzoxazinoid levels, the trichome density was dramatically higher in the wild emmer than in the domesticated wheat. Lastly, we tested the bird cherry-oat aphid’s (Rhopalosiphum padi) performance and found that Chinese Spring is more resistant than the tetraploid genotypes. Conclusions: Our results show that benzoxazinoids play a more significant defensive role than trichomes. Differences between the abundance of defense mechanisms in the wild and domesticated plants were observed in which wild emmer possesses high physical defenses while the domesticated wheat genotypes have high chemical defenses. These findings provide new insights into the defense adaptations of wheat plants against aphids.
Article
Tribolium castaneum (Herbst) is the most resistant agricultural pest species against synthetic pesticides. The search for botanical products that have mechanisms of action with lower residual effects and low toxicity to other animals has increased considerably. This study aimed to examine the phytochemical profile of Genipa americana L. and to evaluate the survival, reproductive, and feeding changes as well as the biochemical parameters of T. castaneum adults fed an artificial diet over 28 days. To this end, we prepared the aqueous extract (50 mM Tris–HCl pH 8.0) of G. americana bark, based on which we performed phytochemical analysis and bioassays in vivo. G. americana bark contain a lectin. The main secondary compounds in the aqueous extract of G. americana were saponins, tannins, and steroids. Aqueous extract of G. americana bark caused insect mortality of 73 % (250 mg of protein/g of wheat flour) and induced a decrease in the hatching rate (40–96%) of T. castaneum larvae. In addition, the extract inhibited insect feeding at the tested doses of 100 mg, 250 mg, and 500 mg, thus having a deterrent effect. Moreover, the extract interfered considerably with all the evaluated nutritional and biochemical parameters. These results contribute to the search for alternative methods for insect pest control and demonstrate the potential of G. americana to be used in integrated management strategies for the control of T. castaneum.
Article
The entomotoxic potential of Manilkara rufula crude extract (CEMR) and its aqueous (AFMR) and methanolic (MFMR) fractions were evaluated against Nauphoeta cinerea cockroaches. The results point out to a direct modulation of octopaminergic and cholinergic pathways in insect nervous system. CEMR induced an anti-acetylcholinesterase (AChE) effect in cockroach brain homogenates. CEMR significantly decreased the cockroach heart rate in semi-isolated heart preparations. CEMR also caused a broad disturbance in the insect behavior by reducing the exploratory activity. The decreased antennae and leg grooming activities, by different doses of CEMR, mimicked those of phentolamine activity, a selective octopaminergic receptor antagonist. The lethargy induced by CEMR was accompanied by neuromuscular failure and by a decrease of sensilla spontaneous neural compound action potentials (SNCAP) firing in in vivo and ex vivo cockroach muscle-nerve preparations, respectively. AFMR was more effective in promoting neuromuscular paralysis than its methanolic counterpart, in the same dose. These data validate the entomotoxic activity of M. rufula. The phentolamine-like modulation induced in cockroaches is the result of a potential direct inhibition of octopaminergic receptors, combined to an anti-AChE activity. In addition, the modulation of CEMR on octopaminergic and cholinergic pathways is probably the result of a synergism between AFMR and MFMR chemical compounds. Further phytochemical investigation followed by a bio-guiding protocol will improve the molecular aspects of M. rufula pharmacology and toxicology to insects.
Article
Palm kernel fixed oil (PKO) extracted by heat (HPKO) and cold-press (CPKO) was evaluated for contact toxicity against Callosobruchus chinensis (L.) at 0–1.5 mL/25 g of cowpea (Vigna unguiculata (L.) Walp) seeds and fungistatic potential against Aspergillus species. In addition, biochemical compounds in the oils were obtained using gas chromatography and mass spectrometric (GC-MS) analysis. One hundred percent mortality of C. chinensis was achieved with ≥1 mL HPKO dose levels while the same mortality was achieved with ≥0.75 mL CPKO dose levels at 24, 48, 72 and 96 h post treatment. Zones of inhibitions (cm) of A. niger (0.93 ± 0.07) and A. flavus (1.27 ± 0.15) with HPKO were comparably higher than zones of inhibitions of A. niger (0.20 ± 0.06) and A. flavus (1.13 ± 0.03) with CPKO. The relative abundance of major compounds in HPKO was Lauric acid > caprylic acid > capric acid while 9-Octadecenoic acid -, 2,3-bis[(trimethylsilyl)oxy]propyl ester > Butanoic acid trimethylsilyl ester > Tetradecanoic acid trimethylsilyl ester in CPKO. The higher percentage of lauric acid in HPKO may account for its greater insecticidal and fungistatic potentials.
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Quinoa (Chenopodium quinoa) has been identified as a unique plant with several benefits that could solve several challenges facing mankind. The application of some recent advances in biotechnological techniques could help toward enhancing the production of important metabolites and nutritional attributes and improve the quality of several products that could be derived from quinoa. It is a source of excellent antioxidant activity along with high values of amino acids, carbohydrates, fatty acids, minerals, phenolic compounds, and saponins. Some of these metabolites possess biotechnological relevance in the production of pharmaceutical, insecticidal, biopesticidal, and nematocidal products. This chapter provides detailed information on the utilization of in vitro tissue culturing for effective production of essential metabolites, while the application of somatic embryogenesis methodology has been identified as significant instrument for effective production of virus-free plants. Furthermore, detailed information on the application of metabolomics together with hyphenated analytical and spectroscopic methodology which included gas chromatography coupled to mass spectrometry, liquid chromatography, and nuclear magnetic resonance spectrometry is provided. Relevance of synthetic biology, informatics, computational biology, and bioinformatics together with nanotechnology on how they could improve some bioactive constituents derived from quinoa plants was also highlighted.
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Sitophilus oryzae L., Tribolium castaneum (Herbst.), Rhizopertha dominica (F.), and Callosobruchus chinensis L. are the primary insect pests that cause significant quantitative and qualitative deterioration of agrifood commodities during postharvest storage. Synthetic insecticides methyl bromide, phosphine, organophosphate, and carbamate are the primary control majors of insect pests. However, in view of recent reports on risks associated with synthetic insecticides viz., resistance, residual toxicity, and the resurgence of new pests, the food industries are looking toward safer alternatives. Currently, in view of biodegradable nature and favorable safety profiles, different plant products have been recognized as preferred alternatives to synthetic insecticides. The recent developments in extraction methods, biotechnological advances, and nanotechnology boost the commercialization of plant-based products as botanical pesticides. The article outlines the potential use of plant products in the management of insect pests of food grains with an emphasis on the technological challenges that must be addressed before recommendation for commercial application as biorational insecticides.
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To avoid potential harm during pupation, the Colorado potato beetle Leptinotarsa decemlineata lives in two different habitats throughout its developmental excursion, with the larva and adult settling on potato plants and the pupa in soil. Potato plants and agricultural soil contain a specific subset of aromatics. In the present study, we intended to determine whether the stage-specific bacterial flora plays a role in the catabolism of aromatics in L. decemlineata. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the operational taxonomic units (OTUs) obtained by sequencing of culture-independent 16S rRNA region enriched a group of bacterial genes involved in the elimination of mono- and polycyclic aromatics at the pupal stage compared with those at the larval and adult periods. Consistently, metabolome analysis revealed that dozens of monoaromatics such as styrene, benzoates, and phenols, polycyclic aromatics, for instance, naphthalene and steroids, were more abundant in the pupal sample. Moreover, a total of seven active pathways were uncovered in the pupal specimen. These ways were associated with the biodegradation of benzoate, 4-methoxybenzoate, fluorobenzoates, styrene, vanillin, benzamide, and naphthalene. In addition, the metabolomic profiles and the catabolism abilities were significantly different in the pupae where their bacteria were removed by a mixture of three antibiotics. Therefore, our data suggested the stage-dependent alterations in bacterial breakdown of aromatics in L. decemlineata.
Chapter
Opuntia ficus-indica (L.) Mill, commonly called prickly pear or nopal cactus, belongs to the Cactaceae family. Opuntia ficus-indica (L.) Mill is a dicotyledonous angiosperm plant, known, since the dawn of time, for its ability to thrive under environments recognized as stressful for most plant species. Opuntia ficus-indica has been used for a long time as diet, fodder, and beverage for both humans and animals, as well as to prevent soil erosion and to combat desertification. Opuntia ficus-indica has traditionally marked the folk medicine, owing to its therapeutic properties to a plethora of bioactive molecules, involving organic acids, phenolic acids, flavonoids, betalains, carotenoids, vitamins, biothiols, taurine, saponins, fatty acids, and phytosterols. The content of these bioactive molecules varies within cladodes, fruits or prickly pears, peels, seeds, and flowers. Whereas pears were commonly considered as noble fruits, peels have been arisen in the last decades as a promising by-product for both animals and humans health and nutrition. Nowadays, there is compelling evidence that Opuntia cacti are functional foods, source of nutrients, and bioactive molecules endowed with high antioxidant potential, and a large specter of biological, medicinal, and pharmacological applications. Indeed, Opuntia ficus-indica is highlighted as an excellent source of natural pigments, having promising applications in food industry and cosmetic. The present chapter aims to stressing the major classes of bioactive phytochemicals from Opuntia ficus-indica, with a deep understanding of the basis of their antioxidant activities, as well as an overview of their biological and medicinal properties.
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Background Young wheat plants are continuously exposed to herbivorous insect attack. To reduce insect damage and maintain their growth, plants evolved different defense mechanisms, including the biosynthesis of deterrent compounds named benzoxazinoids, and/or trichome formation that provides physical barriers. It is unclear whether both of these mechanisms are equally critical in providing an efficient defense for wheat seedlings against aphids—an economically costly pest in cereal production. Results: In this study, we compared the transcriptome, metabolome, benzoxazinoids, and trichome density of three selected wheat genotypes, with a focus on differences related to defense mechanisms. We chose diverse wheat genotypes: two tetraploid wheat genotypes, domesticated durum ‘Svevo’ and wild emmer ‘Zavitan,’ and one hexaploid bread wheat, ‘Chinese Spring.’ The full transcriptomic analysis revealed a major difference between the three genotypes, while the clustering of significantly different genes suggested a higher similarity between the two domesticated wheats than between either and the wild wheat. A pathway enrichment analysis indicated that the genes associated with primary metabolism, as well as the pathways associated with defense such as phytohormones and specialized metabolites, were different between the three genotypes. Measurement of benzoxazinoid levels at the three time points (11, 15, and 18 days after germination) revealed high levels in the two domesticated genotypes, while in wild emmer wheat, they were below detection level. In contrast to the benzoxazinoid levels, the trichome density was dramatically higher in the wild emmer than in the domesticated wheat. Lastly, we tested the bird cherry-oat aphid’s ( Rhopalosiphum padi ) performance and found that Chinese Spring is more resistant than the tetraploid genotypes. Conclusions: Our results show that benzoxazinoids play a more significant defensive role than trichomes. Differences between the abundance of defense mechanisms in the wild and domesticated plants were observed in which wild emmer possesses high physical defenses while the domesticated wheat genotypes have high chemical defenses. These findings provide new insights into the defense adaptations of wheat plants against aphids.
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Background: Young wheat plants are continuously exposed to herbivorous insect attack. To reduce insect damage and maintain their growth, plants evolved different defense mechanisms, including the biosynthesis of deterrent compounds named benzoxazinoids, and/or trichome formation that provides physical barriers. It is unclear whether both of these mechanisms are equally critical in providing an efficient defense for wheat seedlings against aphids—an economically costly pest in cereal production. Results: In this study, we compared the transcriptome, metabolome, benzoxazinoids, and trichome density of three selected wheat genotypes, with a focus on differences related to defense mechanisms. We chose diverse wheat genotypes: two tetraploid wheat genotypes, domesticated durum ‘Svevo’ and wild emmer ‘Zavitan,’ and one hexaploid bread wheat, ‘Chinese Spring.’ The full transcriptomic analysis revealed a major difference between the three genotypes, while the clustering of significantly different genes suggested a higher similarity between the two domesticated wheats than between either and the wild wheat. A pathway enrichment analysis indicated that the genes associated with primary metabolism, as well as the pathways associated with defense such as phytohormones and specialized metabolites, were different between the three genotypes. Measurement of benzoxazinoid levels at the three time points (11, 15, and 18 days after germination) revealed high levels in the two domesticated genotypes, while in wild emmer wheat, they were below detection level. In contrast to the benzoxazinoid levels, the trichome density was dramatically higher in the wild emmer than in the domesticated wheat. Lastly, we tested the bird cherry-oat aphid’s ( Rhopalosiphum padi ) performance and found that Chinese Spring is more resistant than the tetraploid genotypes. Conclusions: Our results show that benzoxazinoids play a more significant defensive role than trichomes. Differences between the abundance of defense mechanisms in the wild and domesticated plants were observed in which wild emmer possesses high physical defenses while the domesticated wheat genotypes have high chemical defenses. These findings provide new insights into the defense adaptations of wheat plants against aphids.
Article
To assess the susceptibility of pseudocereals (amaranth and quinoa), minor cereals (teff and millet), and oilseeds (chia and hemp), now commercially available on the European market, to attacks by polyphagous and cosmopolitan insect pests, laboratory tests were set up. Tests involving controlled infestation of seeds, using laboratory-bred insects (Tenebrio molitor, Tribolium confusum, Oryzaephilus surinamensis, Cryptolestes pusillus and Plodia interpunctella), were carried out in a climatic chamber at 23 ± 2 °C and 65 ± 5% R.H.. Development time, the number of adults and the weight of these adults were evaluated. The results show that each considered foodstuff has a different susceptibility to infestation and differences both in the number of adults emerged and in their weight compared to control. Millet was the only product that allowed larval development up to the adult stage for all the species examined. No species developed on amaranth. T. confusum and O. surinamensis reached the adult stage on the greatest number of products, 5 and 4 respectively; C. pusillus and T. molitor completed their life cycles on only two commodities: millet and teff, while P. interpunctella only on millet and hemp seeds. Considering the impact of the different pests on the studied grains, T. confusum was the only species able to develop on all the grains, but the number of emerged adults was lower than on the standard diet. These results show that, even if these commodities are new in the European market, they are susceptible to the infestation of common stored product pests that could led to a removal from the market of a contaminated stock, so a continuous monitoring is needed.
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Saponin isolated from medicinal plants is a naturally occurring bioorganic molecule with high molecular weight and its aglycone (water non-soluble part) nucleus having 27 to 30 carbon atoms besides one or two sugar moieties (water soluble part) containing at least 6 or 12 carbon atoms respectively. The complexity of saponin chemistry maybe considered as a gap for many scientists and researchers to understand the relationship between the chemical structure and its medical or pharmaceutical behavior. Recently, the increase in demand of saponin applications was observed due to various biological, medicinal, and pharmaceutical actions. Therefore, this present review article provides detailed information about the chemistry of saponin, especially triterpenoid saponin. Classifications, chemical structure, the possible traditional isolation ways, qualitative, and quantitative determination of saponins were included exclusively. Examples of mono and bidesmosidic structure of oleanolic acid and hederagenin also outlined. Structural differences between triterpenoid, steroid, and alkaloid glycosides were summarized according to their atoms, rings, and functional groups. Keywords: Saponine, chemistry, isolation, medicinal plants, extraction, determination, triterpenoid, steroidal saponin, alkaloidal saponin
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The role of agriculture is very much important in the economic growth of a country. As balance diet is the basic requirement of living organisms for their survival; hence, agricultural sector is the major contributor of food and nutrition. With the increase of population rate, the demand of agricultural productivity increases. However, pathogen (viruses, bacteria, fungi, insects, and weeds) attacks lead to crop damage and decreased productivity, which eventually cause starvation and economical loss. To control pests and protect crop damage, agricultural scientists suggest various strategies to increase agricultural productivity by using various chemical and biological agents. Pesticides, insecticide, fungicides, and herbicides are frequently used chemicals for crop protection as well as to increase the productivity. It is important to determine and maintain the safety level of pesticides and restrict their use to the infected field; otherwise, escape of such chemogenic substance to the environment causes intoxication to human and other organisms. For the health and environmental safety, it is essential to devise a proper pesticide management system and a sensitive detection method. Various conventional methods are available for pesticide analysis, but most of them are laborious, time‐consuming, and costly. Advancement in the field of nanobiotechnology has led to the development of biosensors. Biosensors are tools and devices used for the early and rapid detection of toxic chemical compounds in the environment. Biosensor‐based pesticide detection techniques are simple, cost‐effective, and eco‐friendly and can sense pollutants in a minute quantity. This chapter describes an overview of different types of pesticides, their uses to control various pests, and adverse effects on human beings, animals, and their environment. The major focus is on the development of various ultrasensitive biosensors for the detection of pesticides and their residues.
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The toxicity of Catunaregam tomentosa (Blume ex DC.) Tirveng crude extracts against 1st - 4th instar larvae of Aedes aegypti Linn were investigated. The results showed that ethanol extracts from the endocarp and fruit exhibit higher capacity on mosquito larvae than aqueous extracts. The ethanolic endocarp extracts showed the highest toxic to 1st - 4th instar larvae with LC50 of 429.20, 225.55, 95.34, and 283.71 ppm at 30, 36, 54, and 54 hr, respectively.
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Background Wheat is a staple crop that suffers from massive yield losses caused by cereal aphids. Many factors can determine the abundance of cereal aphids and the damage they cause to plants; among them are the plant’s genetic background, as well as environmental conditions such as spatial position within the plot, the composition and the distance from neighboring vegetation. Although the effects of these factors have been under scrutiny for many years, the combined effect of both factors on aphid populations is not fully understood. The goal of this study was to examine the collective impact of genotype and environment on wheat phenology (developmental stages), chemical diversity (metabolites), and insect susceptibility, as manifested by cereal aphid abundance. Methods To determine the influence of plant genotype on the metrics mentioned above, we measured the phenology, chemical profile, and aphid abundance of four wheat genotypes, including the tetraploid wild emmer ( Triticum turgidum ssp. dicoccoides cv. Zavitan), tetraploid durum ( Triticum turgidum ssp. durum cv. Svevo), and two hexaploid spring bread ( Triticum aestivum ), ‘Rotem’ and ‘Chinese Spring’. These genotypes are referred to as “focal” plants. To evaluate the impact of the environment, we scored the distance of each focal plant (spatial position) from two neighboring vegetation types: (i) natural resource and (ii) monoculture wheat resource. Results The results demonstrated that the wild emmer wheat was the most aphid-resistant, while the bread wheat Rotem was most aphid-susceptible. Aphids were more abundant in plants that matured early. The spatial position analysis demonstrated that aphids were more abundant in focal plants located closer to the margin monoculture wheat resource rather than to the natural resource, suggesting a resource concentration effect. The analysis of metabolic diversity showed that the levels of three specialized metabolites from the flavonoid class, differed between the wheat genotypes and some minor changes in central metabolites were shown as well. Altogether, these results demonstrate a combined effect of genetic background and spatial position on wheat phenology and aphid abundance on plants. This exposes the potential role of the marginal vegetation environment in shaping the insect population of desirable crops. These findings highlight the importance of maintaining plant intra-specific variation in the agriculture system because of its potential applications in reducing pest density.
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Use of non-glossy collards as a trap crop for control of the diamondback moth, Plutella xylostella (L.), in commercial fields of cabbage in New York was unsuccessful because it neither reduced the number of larvae on cabbage nor concentrated the insects on collards. In laboratory and outdoor screenhouse experiments, P. xylostella preferentially laid its eggs on the glossy-type Barbarea vulgaris, a common biennial weed, when compared with broccoli and cabbage. Ovipositional preference in the screenhouse trials varied from 24 to 66 fold for B. vulgaris. However, no larvae were able to develop on B. vulgaris. More importantly, cabbage plants in screenhouses with B. vulgaris had fewer eggs laid on them than cabbage plants in screenhouses without B. vulgaris. We therefore suggest that B. vulgaris, or another plant species that is highly attractive for egg laying, but on which P. xylostella larvae do not survive, may serve as a ‘dead-end’ trap crop and be more successful than trap crop types that may only have increased oviposition. However, candidate dead-end trap crops must also be evaluated for their effects on other insects, diseases and weed management before such plants can be recommended in an overall pest management program.
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Naturally occurring saponins are a large group of triterpene and steroid glycosides characterized by several biological and pharmacological properties. The Medicago genus represents a valuable source of saponins which have been extensively investigated. This review summarizes the chemical features of saponins from Medicago species and their biological activity, with particular attention to their antimicrobial, insecticidal, allelopathic and cytotoxic effects. Influence of saponins on animal metabolism is also reported.
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The total saponins of alfalfa, Medicago sativa L., included in the diet of Colorado potato beetle larvae reduced their feeding, growth rate and survival. The biological activity of those compounds coming both from the roots and from the aerial parts is closely correlated with the dose. Larvae reared on leaves treated with a 0,5% dose virtually did not feed at all and died after 4-6 days. Lower saponin doses (0,01 and 0,001 %) reduced the insects' feeding to a lesser degree. However, they inhibited their growth, caused an extension of the larval stage and mortality at a level of 76,7- 100%. No major differences have been found in saponin activity depending on its localization in the plant.
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The total saponins originating from the roots and shoots of three Medicago species (M. arabica, M. hybrida and M. murex) included in the diet of Colorado potato beetle larvae, reduced their feeding, growth rate and survival. The insecticidal activity of these compounds was closely correlated with the dose. All saponins applied at 0.5% concentration, showed a high insecticidal activity, but saponins from M. murex roots and from aerial parts of M. arabica and M. hybrida were especially active. The growth rate and mortality of the larvae when the saponsis fed at lower dose (0.1%) were similar to control group.
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Herbivorous insects exploit not only the main primary metabolites of plants as nutrients but also many further chemical constituents which have a rich structural and quantitative variability. These constituents, characterized most often as secondary metabolites, possess a wide range of biological activities and functions. Insects utilize frequently such compounds to their benefit, i.e. as kairomones. However, plants defend themselves, in an ecological sense, again with a rich variety of secondary metabolites which have negative effect on insects, i.e. as allomones. These positively or negatively acting substances are often specific with regard to functions or species and can be classified in many ways.
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Four steroidal glycosides including deltoside and nolinofuroside D and two novel saponins were isolated from underground parts of Allium nutans L. On the basis of the spectral (LSIMS and NMR) analysis, the structures of the new compounds were established as 25R Delta(5)-spirostan 3beta-ol-3-O-¿alpha-L-rhamnopyranosyl(1-->2)-[beta-D-glucopyranosyl(1 -->4)]-O-beta-D-galactopyranoside¿ and 25R Delta(5)-spirostan 1beta, 3beta-diol 1-O-beta-D-galactopyranoside. On the basis of the extraction efficiency, the concentration of saponins was established to be about 4% of dry matter, which makes this species a good source of steroidal saponins for commercial use.
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Provides a global overview of the biology and ecology of Plutella xylostella (Lepidoptera: Yponemeutidae), its association with its host plants and natural enemies, and past, present, and future management strategies. The authors give an overview of the characteristics of diamondback moths and past management practices that resulted in widespread control failures, and provide perspectives intended to improve management in the future. Central to control failures is the development of resistance by diamondback moths to every insecticide that has been widely used against them, including Bacillus thuringiensis. Past experiences with diamondback moth management have reinforced the belief that single-component strategies will fail. New technologies such as host-plant resistance, development of new pathogens and insecticides, and mating disruption with pheromones must become available to complement traditional strategies. -from Authors
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 The abundance of insect pests and natural enemies in two varieties of quinua, Chenopodium quinoa (Blanca de Junín and Amarilla de Maranganí) throughout the growing season in the Southern Peruvian Andes is described. The quinua varieties differ, among other traits, in their content of saponins (secondary metabolites associated to plant resistance) late in the season. Whereas Agromyzidae and Cicadellidae were abundant only in the early season, both Chrysomelidae and Aphididae populations showed fluctuations. Likewise, Araneae and Braconidae showed fluctuating numbers during the season. The abundance of Coccinellidae peaked at mid-season whereas that of Syrphidae was high only in the late season. Although the overall abundance of insects was very similar in both varieties of quinua, there were different patterns depending on the season. In the early season there was a tendency towards greater insect numbers on Blanca, but in contrast, in the late season Amarilla (the high-saponin variety) had a higher load of insect pests. This suggests that saponins do not play a major role in quinua resistance against insects. In the early season, no significant relationship between pests and natural enemies held across quinua varieties. In the late season, Aphididae and Coccinellidae were negatively and significantly correlated in both varieties. The temporal population dynamics of Aphididae and both Coccinellidae and Braconidae resembled the traditional predator–prey dynamics.
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Larvae of the leaf-feeding beetles Neolema sexpunctata and Lema trilinea carry feces on their backs that form shields. We used the generalist predatory ant, Formica subsericea, in a bioassay to determine whether shields were a physical barrier or functioned as a chemical defense. Fecal shields protected both species against ant attack. Larvae of both species reared on lettuce produced fecal shields that failed to deter ants. Commelina communis, N. sexpunctata's host, lacks noxious secondary compounds but is rich in phytol and fatty acids, metabolites of which become incorporated into the fecal defense. In contrast, the host plant of L. trilinea, Solanum dulcamara, contains steroidal glycoalkaloids and saponins, whose partially deglycosylated metabolites, together with fatty acids, appear in Lema feces. Both beetle species make modifications to host-derived precursors before incorporating the metabolites into shields. Synthetic chemicals identified as shield metabolites were deterrent when applied to baits. This study provides experimental evidence that herbivorous beetles form a chemical defense by the elimination of both primary and secondary host-derived compounds. The use of host-derived compounds in waste-based defenses may be a more widely employed strategy than was hitherto recognized, especially in instances where host plants lack elaborate secondary compounds.
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Saponins are glycosylated plant secondary metabolites found in many major food crops [Price, K. R., Johnson, I. T. & Fenwick, G. R. (1987) CRC Crit. Rev. Food Sci. Nutr. 26, 27-133]. Because many saponins have potent antifungal properties and are present in healthy plants in high concentrations, these molecules may act as preformed chemical barriers to fungal attack. The isolation of plant mutants defective in saponin biosynthesis represents a powerful strategy for evaluating the importance of these compounds in plant defense. The oat root saponin avenacin A-1 fluoresces under ultraviolet illumination [Crombie, L., Crombie, W. M. L. & Whiting, D. A. (1986) J. Chem. Soc. Perkins 1, 1917-1922], a property that is extremely rare among saponins. Here we have exploited this fluorescence to isolate saponin-deficient (sad) mutants of a diploid oat species, Avena strigosa. These sad mutants are compromised in their resistance to a variety of fungal pathogens, and a number of lines of evidence suggest that this compromised disease resistance is a direct consequence of saponin deficiency. Because saponins are widespread throughout the plant kingdom, this group of secondary metabolites may have general significance as antimicrobial phytoprotectants.
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A spirostanic saponin was isolated from the ethanolic extract of the aerial parts of Solanum laxum Steud. The compound, named luciamin, was characterised by NMR spectroscopy, mass spectrometry and chemical methods, as (22R, 25S)-spirost-5-en-3 beta, 15 alpha-diol 3-O-|beta-D-glucopyranosyl (1 --> 2)-beta-D-glucopyranosyl-( 1 --> 4)-[alpha-L-rhamnopyranosyl-( 1 --> 2)]-beta-D-galactopyranoside|. The compound was tested against the aphid Schizaphis graminum by incorporation in artificial diets. It showed a deterrent (toxic) activity against the insect and is the first spirostane glycoside reported to have this activity.
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Switchgrass (Panicum virgatum L.) has been reported to be hepatotoxic, causing photosensitization in lambs and horses. In this study we show the presence of steroidal saponins in two samples of switchgrass that has been implicated in the poisonings of sheep and horses. After hydrolysis of the saponins, diosgenin was determined to be the major sapogenin in both switchgrass samples. We also confirmed the presence of diosgenin in kleingrass after hydrolysis of saponins extracted from it.
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The herbivore-induced response of alfalfa (Medicago sativa) was examined through assays with Spodoptera littoralis larvae and analyses of important secondary substances. In food preference experiments, larvae preferred young undamaged alfalfa plants over plants that had been damaged by feeding larvae 5 and 7 days earlier. while no difference in feeding preferences could be detected 1. 9. and 14 days after damage. This suggests a peak in the herbivore induced resistance of alfalfa approximately one week after initial damage. The induced resistance in young plants was also shown to be systemic, while older flowering plants failed to show increased resistance after defoliation. Larvae gained weight slower and had lower pupal mass when fed damaged alfalfa than when fed undamaged alfalfa. Levels of total saponins were increased in foliage of damaged alfalfa, and detailed analyses of specific saponin components revealed doubled concentrations of 3GlcA,28AraRhaXyl medicagenate (medicagenic acid bidesmoside) and 3GlcAGalRha soyasapogenol B (soyasaponin I). Levels of the flavonoid apigenin (as free aglycone) also were increased in herbivore damaged plants. The herbivore-induced response of alfalfa was significantly weaker than that of cotton: S. littoralis larvae given a choice of undamaged cotton and undamaged alfalfa preferred to feed on cotton, whereas preferences shifted towards alfalfa when plants were damaged.
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Terpenoids are known to have many important biological and physiological functions. Some of them are also known for their pharmaceutical significance. In the late nineties after the discovery of a novel non-mevalonate (non-MVA) pathway, the whole concept of terpenoid biosynthesis has changed. In higher plants, the conventional acetate-mevalonate (Ac-MVA) pathway operates mainly in the cytoplasm and mitochondria and synthesizes sterols, sesquiterpenes and ubiquinones predominantly. The plastidic non-MVA pathway however synthesizes hemi-, mono-, sesqui- and di-terpenes, along with carotenoids and phytol chain of chlorophyll. In this paper, recent developments on terpenoids biosynthesis are reviewed with respect to the non-MVA pathway.
Chapter
Digestive enzymes in insects are generally adapted to the diet on which the species feed (Wigglesworth, 1965). Blowfly larvae that feed on animal tissues exhibit high protease and lipase activities (Hobson, 1931). Polyphagous insects such as Spodoptera littoralis larvae secrete high levels of protease, amylase, and invertase (Ishaaya et al., 1971, 1974), whereas hemipterous insects such as aphids and scales, which usually feed on plant fluid, exhibit a relatively high level of invertase activity (Ishaaya and Swirski, 1970, 1976). Nutritional and environmental factors affect digestive enzymes; the digestive proteolytic and amylolytic activities of Spodoptera littoralis, for example, are closely correlated with the protein level in the diet or with the environmental temperature (Ishaaya et al., 1971). In some cases digestive enzymes can be used as parameters for assessing anti-feeding activity (Ascher and Ishaaya, 1973; Ishaaya and Casida, 1975; Ishaaya et al., 1974, 1977, 1980, 1982), or phagostimulation (Ishaaya and Meisner, 1973). Despite availability of ample information concerning biochemical properties of digestive enzymes in various insects (House, 1974; Wigglesworth, 1974), relatively little is known about their role in 410insect feeding and insect-host compatability. Trehalase, another carbohydrase that in insects degrades trehalose to glucose for internal energy supply (Wyatt, 1967), is used as a biochemical parameter for assessing the adaptability of the black scale Saissetia oleae to various host plants (Ishaaya and Swirski, 1976). In Aphis citricola, two types of aphid trehalase have been identified: one is water-soluble and the other is a membrane-bound enzyme. An increased level of the soluble trehalase in the alate morphs of Aphis citricola indicates the importance of this enzyme system in the energy supply needed for aphid flight (Neubauer et al., 1980).
Article
It was proved that tea-seed saponins (TSS) showed the growth inhibitory activity to the weed seed-lings, early watergrass (Panicum Crus-galli L.), green foxtail (Setaria viridis Beauv. L.) and white clo-ver (Trifolium repens L.) at concentrations more than 10 mg/L. However, this activity was lower than agricultural chemicals. The additive growth inhibitory effect of TSS and glyphosate (isopropylammo-nium N-(phosphonomethyl)glycinate), which is one of the most popular weed killers in Japan, was investigated to prove that TSS additively increased the growth inhibitory effect of glyphosate to early watergrass seedlings. This result suggests that TSS could be utilized as growth inhibitory agents of weed seedlings in combination with other agricultural chemicals.
Article
The potencies of 19 ecdysteroids are compared in the B11 bioassay, which reflects the affinity of binding site of the Drosophila melanogaster ecdysteroid receptor. The compounds tested represent either natural products isolated from plants (phytoecdysteroids) or fungi (mycoecdysteroids) or synthetic analogues based on insect metabolites (zooecdysteroids). None of the tested compounds showed any antagonistic activity, but all possessed quantifiable agonistic activity. All the mycoecdysteroids were less potent than the major insect ecdysteroid, 20-hydroxyecdysone (20E). Also, conjuration of 20E with a glucose moiety results, as expected, in considerable reduction in biological activity, but the remaining activity is dependent on the position of conjugation. The implications of these findings for the structure/activity relationship of ecdysteroids are discussed. Arch. Insect Biochem. Physiol. 35:219–225, 1997. © 1997 Wiley-Liss, Inc.
Article
Insecticidal activity of plant material (seeds and leaves) and extracts of Trigonella foenum-graecum from two sources against the stored product pests Tribolium castaneum and Acanthoscelides obtectus was investigated. Topical applications of extracts produced a high degree of mortality in both insects (at 6 and 30 μg/insect). Powdered fenugreek seeds or extracts applied to Phaseolus vulgaris beans produced mortality and inhibited opposition and larval penetration by A. obtectus. The presence of the plant material decreased A. obtectus fecundity and reduced its longevity. Fenugreek seed appeared moderately toxic to young larvae of T. castaneum (LD25 = 18% in diet), and surviving adults showed progressively decreased fecundity as the dose of seeds, especially ripe seed, was increased. Significant effects of dose, seed ripeness and their interaction were produced. The seed affected the fertility of both sexes. Some fertility was recovered on reversion to the standard diet. Possible active compounds and the implications of the results for pest control are discussed.
Article
The effects of some secondary plant compounds in a 5-d bioassay on the survival and mean weight of surviving nymphs of the migratory grasshopper, Melanoplus sanguinipes (F.), are described. In total, 22 secondary plant compounds were individually added to the dry diet in six concentrations. No significant treatment effects were observed with harmalol, harmol, quercetin, or with caffeic, p-coumaric, ferulic, gentisic, or syringic acids. Both naringenin and rutin significantly affected mean weight but not survival. Saponin significantly decreased survival. Oleanolic and chlorogenic acids and sparteine significantly decreased mean weight. Vanillic acid significantly increased mean weight. Gramine, harmaline, harmane, harmine, hordenine, scopoletin, and flavone significantly decreased survival and mean weight.
Article
The effects of wild and cultivated Brassicaceae host plants on diamondback moth, Plutella xylostella (L.), oviposition, egg hatch, larval survival, infestation level, parasitism rate by Diadegma insulare (Cresson), and the developmental time and sex ratio of D. insulare were studied. Diamondback moth egg laying was highest on the Brassica crops, especially broccoli, and lowest on wild Brassicaceae, especially Berteroa incana L. DC. and Erysimum cheiranthoides L. Percentage of egg hatch was not significantly different among host plants. Diamondback moth larval survival was generally higher on the Brassica crops than on wild Brassicaceae and there was no survival on Barbarea vulgaris R. Br. Developmental time of diamondback moth larvae was generally longer on the wild Brassicaceae than on the Brassica crops. Percentage of parasitism by D. insulare was lowest on B. incana, Lepidium campestre R. Br. and E. cheiranthoides. Percentage of parasitism was higher when diamondback moth larvae fed on B. kaber than on the wild Brassicaceae. When fed on E. cheiranthoides, Thlaspi arvense L., and B. incana, parasitized diamondback moth larvae took significantly longer time to develop to D. insulare pupae than when they were fed on the other Brassicaceae plants. The female/male sex ratio was higher on Brassica species than on non-Brassicas. Diamondback moth infestation and percentage of parasitism in the field were higher on broccoli than on the other Brassica crops, but the proportion of D. insulare females versus males was not significantly different. The presence of wild Brassicaceae, especially B. vulgaris and B. kaber, in the field could reduce diamondback moth populations, increase the impact of D. insulare, provide a reservoir for insecticide-susceptible diamondback moth, and increase the success of diamondback moth management programs.
Article
A zahnic acid tridesmoside, 3-O-[beta-D-gluocpyranosyl(1-2)-beta-D-glucopyranosyl(1-2)-beta-D-glucopyranosyl]-2-beta,3-beta,16-alpha-trihydroxyolean-12-ene-23,28-dioic acid-23-O-alpha-L-arabinopyranosyl-28-O-[beta-D-apiofuranosyl-(1-3)-beta-D-xylopyranosyl(1-4)-alpha-L-rhamnopyranosyl(1-2)-alpha-L-arabinoside], has been identified as the main saponin present in the aerial parts of alfalfa by a combination of chromatographic, chemical, and spectroscopic techniques. Moreover, four medicagenic acid glycosides and soyasaponin I have been isolated from the same source and identified. Three of the medicagenic acid glycosides are identical to those previously found in alfalfa roots, while the fourth has been identified as 2-beta-hydroxy-3-beta-O-glucuronopyranosyl 28-O-[alpha-L-rhamnopyranosyl(1-2)-alpha-L-arabinopyranoside]olean-12-en-23-oic acid. Biological activity was measured using the fungus Trichoderma viride, and hemolytic activity was assessed using a hemolytic test. The zahnic acid glycoside did not inhibit fungal growth over a wide range of concentrations and exhibited only weak hemolytic activity.
Article
Soybean saponins were found to inhibit, to a certain extent, cholinesterase and the proteolytic activity of chymotrypsin, trypsin, papain, and Tribolium castaneum larval midgut enzyme solution. It has been shown that this nonspecific inhibition results from a protein (i.e., enzyme) saponin interaction, since pre-incubation of the saponin with various proteins prior to enzyme-substrate interaction could abolish the inhibitory effect of the saponins.
Article
Fourteen plant allelochemicals, all of which are strong antifeedants to stored product coleopterans, were evaluated as antifeedants and larval growth inhibitors against the variegated cutworm, Peridroma saucia, and the bertha armyworm, Mamestra configurata (Lep., Noctuidae). Bisabolangelone, a sesquiterpene, podophyllotoxin, a lignan, and aginosid, a saponin, are strongly deterrent to P. saucia larvae in a feeding choice test. When added to artificial diets, the sesquiterpene lactone bakkenolide A was the most inhibitory to larval growth of neonate cutworms, whereas bisabolangelone was the most inhibitory to neonate armyworms. Toxicity of bakkenolide A, xanthotoxin (a furanocoumarin), and podophyllotoxin to insects is discussed. Zusammenfassung: Natürlich vorkommende Fraßhemmstoffe: Wirkung auf zwei polyphage SchmetterlingsartenInsgesamt wurde die fraßabschreckende und wachstumshemmende Wirkung von 14 allelochemischen Pflanzeninhaltsstoffen, die alle eine starke fraßhemmende Wirkung auf Vorratsschädlinge aus der Ordnung der Käfer haben, bei Peridroma saucia und Mamestra configurata (Lep., Noctuidae) getestet. Bisabolangelon, Podophyllotoxin und Aginosid erwiesen sich bei P. saucia im Fraßtest als stark fraßhemmend. Wurde Bakkenolid A dem Kunstfutter beigemischt, so zeigte es gegenüber jungen P. saucia-Larven die höchste wachstumshemmende Wirkung, wohingegen Bisabolangelon den höchsten Wirkungsgrad gegenüber M. configurata-Larven aufwies. Die Toxizität von Bakkenolid A, Xanthotoxin und Podophyllotoxin gegenüber den getesteten Insektenarten wird diskutiert.
Article
  Saponin extract from alfalfa roots, azadirachtin from the neem seed oil, synthetic ecdysteroid agonist RH-2485, and the juvenoid hydroprene disturb the development and reproduction of Tropinota squalida. Feeding beetles on diets containing 750 p.p.m. saponins, 7.5 p.p.m. RH-2485, and 1.13 p.p.m. azadirachtin reduces their progeny from 51 second instar larvae per female to 24, 15, and 15 larvae, respectively. When the larvae of untreated adults are fed for 1 week on dung with 75 p.p.m. saponins, 50 p.p.m. RH-2485, and 0.45 p.p.m. azadirachtin, the rate of adult emergence drops from 80% (controls) to 20, 0 and 13%, respectively. No adults emerge when the treatment is continued through the second and third larval instars. Two topical treatments of larvae with 0.2 μg hydroprene decrease the rate of adult emergence from 90 to 11%, and treatments with 2 μg prevent adult development in all insects. The observed effects warrant testing of azadirachtin, RH-2485, and hydroprene in the field. Several types of their application for the control of T. squalida are suggested.
Article
Plants have evolved a variety of chemical means to deter herbivory. Several studies have documented that secondary compounds are strong deterrents to certain herbivores, while others have demonstrated that some herbivores ingest large quantities of these compounds without exhibiting deleterious effects. This inconsistent response suggests that plants have evolved compounds to deter specific herbivores. Based on a study in Kibale National Park, Uganda, we explored how two major groups of herbivores, invertebrates and colobus monkeys, respond to chemical characteristics of leaves: protein, attractive from a nutritional perspective, and alkaloids, saponins and cyanogenic glycosides, which are all plant defences, detering herbivory. The intensity that colobus monkeys fed on leaves of different tree species was determined by observations (1300 h), and invertebrate herbivory was indexed by collecting leaves from 20 species and digitizing tracings to quantifying invertebrate damage. Invertebrate damage to leaves varied among species (1.5–22.5%), but showed no relationship with saponin or protein content, or the presence or absence of alkaloids. Colobine foraging effort did not relate to the saponin and protein of leaf species, nor to the presence or absence of alkaloids. Prunus africana, the only species to test positive for cyanogenic glycosides, was fed on by colobus monkeys for 8.1% of their foraging time, but, as it occurred at low densities, it was the most preferred species. These results can be interpreted in different ways. First, it is possible that inactive compounds are retained because they increase the probability of producing new active compounds. Secondly, the indices used to evaluate compound effects may be inappropriate. For example, monkeys may only be able to tolerate a toxin to a specific threshold in a single feeding session, but our index of foraging effort was averaged over the year. Thirdly, it may be that these compounds play an active role with organisms not considered (e.g. prevent fungal attack). Finally, these compounds may serve some unknown function and selection may operate for that purpose. Les plantes ont développé des divers moyens de dissuasion contre les herbivores. Plusieures études ont rapporté que des composés secondaires agissent comme une forte dissuasion pour certains herbivores, alors que d'autres ont démontré qu'il y a des herbivores qui peuvent ingérer les mêmes composés en grande quantité sans manifester des effets nuisibles. Cette réponse incohérente indique que les composés ont évolué pour dissuader des herbivores spécifiques. Basé sur une étude au parc national de Kibale en Uganda, nous avons enquêté comment deux groupes majeurs d'herbivores – invertébrés et singes colobus - réagissent aux caractéristiques chimiques des feuilles; la protéine, qui devrait être considérée sur une perspective nutritionnelle, et alcaloïdes, saponines et glycosides cyanogènes, qui sont tous des protections utilisées par la plante qui devait dissuader les herbivores. Nous avons établi l'ampleur de la consommation de feuilles par les singes colobus à travers des observations (1300 hr), tandis que l'herbivorie des invertébrés fut indexé suite au recueil de 20 espèces de feuilles et la numérisation des traçages afin de quantifier les dégâts faits par les invertébrés. Les dégâts variaient selon l'espèce (1.5 à 22.5%), mais n'indiquaient aucun lien avec le contenu de saponines et protéines, ni la présence ou l'absence des alcaloïdes. A cet égard nous avons trouvés les mêmes résultats chez le fourrage des singes colobus. Prunus Africana, la seule espèce à contenir des glycosides cyanogènes, représentait 8,1% de l'alimentation des singes, mais – puisqu'elle était rare – s'avérait l'espèce préférée. Ces résultats peuvent être interprété de plusieurs façons. Premièrement, il est possible que les composés passifs soint retenus parce qu'ils augment la probabilité que la plante produise des nouveaux composés actifs. Deuxièmement, les indicateurs employés afin d’évaluer les effets des composès sont peut-être impropres. Par exemple, il se peut que le singe puisse tolérer une toxine jusqu’à un certain niveau lors d'une séance, alors que notre indexe du niveau de fourrage fut moyenné sur l'année. Troisièmement, il est possible que les composés jouent contre des organismes que nous n'avons pas considéré ici, (par exemple. pour éviter une attaque fongique). Dernièrement, les composés peuvent avoir une fonction que nous ignorons et qui réagit sur la sélection.
Article
Saponins of DuPuits and Lahontan alfalfa cultivars were extracted and fractionated by preparative thin-layer chromatography. The ten relatively well-defined saponin fractions obtained from each cultivar were chemically characterized by major aglycone and carbohydrate moieties. Lahontan contained considerably more soyasapogenol A than DuPuits, but medicagenic acid predominated in DuPuits. The near absence of medicagenic acid from Lahontan fractions was the most significant difference in composition of Lahontan and DuPuits saponins. Based on mass-spectrometric analyses, four unidentified sapogenins were classified as the same pentacyclic triterpenoids as medicagenic acid or soyasapogenol. Six Lahontan fractions incorporated varying quantities of galactose, which was present in only two DuPuits fractions, but more arabinose was found in DuPuits than in Lahontan saponins. Simplified saponins of DuPuits and Lahontan were then bioassayed by survival of potato leafhopper (Empoasca fabae (Harris)), survival of pea aphid (Acyrthosiphon pisum (Harris)), hemolysis of human blood cells, and inhibition of Trichoderma viride Pers. ex Fr. A crudesaponin mixture and a commercially available saponin from Yucca sp. were included in all assays as controls. Certain fractions containing medicagenic acid were responsible for toxic properties in all assays. Presence or absence of medicagenic acid seemed to explain most of the differences in biological activity of DuPuits and Lahontan cultivars. However, medicagenic acid apparently is not the only acid sapogenin strongly active toward pathogens. An unidentified acid sapogenin chemically related to medicagenic acid inhibited fungal growths markedly, but did not affect insects tested. Potato leafhopper and pea aphid appeared to be appropriate test insects for saponin differentiation.