Deterrent activity of sesquiterpene lactones from the umbelliferae against storage pests

The deterrent activity of eight native sesquiterpene lactones isolated from the species Laserpitium siler L., L. archangelica Wulf. and Laser trilobum (L.) Borkh. and one synthetically prepared lactone have been tested against selected storage pest insects. All nine lactones under investigation showed deterrent activity differing according to their structure.     

Insect feeding deterrent activity of bisabolangelone and of some sesquiterpenes of eremophilane type

The insect feeding deterrent activity of some sesquiterpenes of furanoeremophilane type and of the related eremophilanolide type were tested towards three selected storage pests: Sitophilus granarius, Tribolium confusum and Trogoderma granarium. The results were compared with the biogenetically related compound of bakkenolide type, known as a potent antifeedant. Bisabolangelone, tested on the same insects, exhibited the strongest activity, and may be included in the class of very good insect feeding deterrents. The antifeeding activity of bisabolangelone and bakkenolide A towards larvae of Leptinotarsa decemlineata was also observed.     

Insecticidal effects of Vernonanthura nebularum against two economically important pest insects

Vernonanthura nebularum (Cabrera) H. Rob. (Asteraceae), an endemic species from the north of Argentina, is a rich source of elephantopus-type sesquiterpene lactones. These compounds have proved to be promising antiparasitic agents, but there is no report about their action against pest insects. In this work we studied for the first time the antifeedant and toxic effects of V. nebularum natural products against the fall army warm Spodoptera frugiperda Smith and the oviposition deterrent activity against the fruit fly Ceratitis capitata Wiedemann. As a result, we found that extracts, fractions composed of sesquiterpene lactones and pure sesquiterpene lactones altered larval feeding behavior in the food choice test. Nutritional parameters of S. frugiperda larvae were also affected. Fraction II (300 μg/g of diet.), containing compounds 1, 2 and 3, was the most toxic substance with 80% pupal mortality and wing malformations in adults. In oviposition deterrent experiments against Ceratitis capitata, we observed a moderate effect at 30 μg/cm² of the test compound. The most active substances were the methanolic extract, dichloromethane subextract and lactone 2. According to our results, V. nebularum natural products could be used for maximizing the effectiveness and specificity in future insecticide design with specific or multiple target sites, while ensuring the economic and ecological sustainability, in addition to combat the increasing resistance rates developed by synthetic pesticides.     

Effects of the sesquiterpene lactone,helenin, on feeding rates and survival of the tundra redback vole Clethrionomys rutilus

The sesquiterpene lactone, helenin, acts as a feeding deterrent to redback voles, Clethrionomys rutilus. When given a choice between normal and treated food, these animals avoided food containing at least 0.05% of helenin. However, when only offered food with various concentrations of helenin, feeding rate and consequently body weight of voles were sharply reduced when the helenin concentration was 1.5% or higher. Voles given food containing 3.0–7.0% of helenin died in 3–5 days. It is suggested that these effects of helenin are the result of its antifeedant property and subsequent starvation of animals as well as its interference with digestive processes. The data presented support the view that helenin and other sesquiterpene lactones may play an important role in the defence of plants against herbivorous mammalian predators.     

Sesquiterpene lactones from Centaurea glomerata

The investigation of the aerial parts of Centaurea glomerata afforded four new sesquiterpene lactones of the germacradienolide type and the lignan lactone arctigenin. Their structures were elucidated by spectroscopic methods.     

Insect feeding deterrent activity of lignans and related phenylpropanoids with a methylenedioxyphenyl (piperonyl) structure moiety

The antifeedant activity of a series of lignan lactones, hemiacetals, ethers, and alcohols derived from yatein and cubebin, together with structurally related phenylpropanoids and phenolics possessing a methylenedioxyphenyl (piperonyl) moiety, was tested against selected stored products pests: Sitophilus granarius L. (Coleoptera: Curculionidae), Tribolium confusum Duv. (Coleoptera: Tenebrionideae), and Trogoderma granarium Ev. (Coleoptera: Dermestridae). The relation between molecular structure and antifeedant activity was examined and implication of the piperonyl moiety is assessed. The compounds represent either natural substances isolated from plants (Libocedrus yateensis Guillaumin and Piper cubeba L.) or their structural analogues prepared by simple chemical transformations as well as compounds selected from commercially available sources. Natural lignan lactones with methoxy and/or methylenedioxy substituents showed significant activity that is strong enough to affect plant - insect interactions. Presence of polar substituents, especially hydroxy or glycosyl groups, often reduce the activity. Non-polar substituents, such as methoxy or methylenedioxy groups, enhance the activity not only in lignans but also in simple phenylpropanoids. The most active compound was synthetic piperonylbutoxide.     

Plant essential oils: a substitute for conventional insecticides against Tribolium species (Coleoptera: Tenebrionidae)-achievements and challenges

Abstract

The literature on efficacy of plant essential oils and their constituents for the management of Tribolium spp. (T. castaneum and T. confusum), instigating infestation of a variety of stored grains and their products is reviewed here. Both species caused significant losses in the diverse food grains and their products through infestation. Essential oils of higher plants showed potential activity in the management of these infestation driven losses. Researchers have found that essential oils and their chemical constituents have significant toxicity against both the species of Tribolium via different modes of action like repellent, insecticidal, ovicidal, larvicidal, pupicidal, ovipositional and feeding deterrent actions. Concerning repellency and in vivo bioassays, few studies have been done with the essential oils against T. confusum, thus, more investigations are required to find the repellent agents against this insect. There are some essential oil-based botanical insecticides which have been proved effective for the protection of food grains from both beetles during storage. These botanical insecticides also exhibited behaviour altering properties against both beetles, thus, reducing the problem of pest resistance which is a problem with conventional insecticides. Therefore, essential oils-based botanical insecticides may be preferred option than conventional insecticides for protecting stored grains and their products against Tribolium infestation.     

Oxepane diterpenoids sesquiterpene lactones from ‘zoapatle’ (montanoa tomentosa), a mexican plant with oxytocic activity

Investigation of the ‘tea’ prepared from the leaves of ‘zoapatle’ (Montanoa tomentosa), resulted in the isolation of the known biologically active oxepane diterpenoids zoapatanol and montanol, the known sesquiterpene lactones zoapatanolide A, C and D as well as two new biologically active oxepane diterpenoids and a new sesquiterpene lactone. The structures of the new compounds were established by spectroscopic methods.     

Sesquiterpene lactones in various populations of Parthenium hysterophorus

Samples of 31 populations of Parthenium hyserophorus from varius areas of its world distribution were examined for their sesquiterpene lactone composition. On the basis of the occurrence of sesquiterpene lactones the samples were divided into seven chemical types. The most common is a type represented by plants containing parthenin as a major sesquiterpene lactone, and coronopilin and tetraneurin-A. All samples from North and Central America, Venezuela, South Africa, India, Australia, and one sample from Jamaica belong to this type. This suggests that P. hysterophorus recently introduced to South Africa, India and Australia originates in North and (or) Central America. On the other hand, there is a great diversity among examined South American populations. Plants from these populations usually contain hymenin which is their major sesquiterpene lactone. Some populations may also contain coronopilin, hysterin, and dihydroisoparthenin. A high diversity in the sesquiterpene lactone chemistry and the morphological differences between individual South American populations of this species indicate the possible existence of several taxa.     

Antiprotozoal activity of 8-acyl and 8-alkyl incomptine A analogs

The activities of 11 C-8-O-acyl and alkyl analogs of the antiprotozoal sesquiterpene lactone, incomptine A (1) against Entamoeba histolytica and Giardia lamblia, were determined. Here, the effects of different lengths and amounts of branching of the acyl and alkyl groups on the antiprotozoal activity of the synthesized incomptine A-analogs are reported.     

Chemo-Enzymatic Synthesis of Optically Active γ- and δ-Decalactones and Their Effect on Aphid Probing,Feeding and Settling Behavior

The enantiomerically enriched γ- and δ-decalactones (4a and 4b) were prepared from corresponding racemic primary-secondary 1,4- and 1,5-diols (1a and 1b), as products of enzymatic oxidation catalyzed by different alcohol dehydrogenases. The results of biotransformations indicated that the oxidation processes catalyzed by alcohol dehydrogenase (HLADH), both isolated from horse liver and recombinant in Escherichia coli, were characterized by the highest degree of conversion with moderate enantioselectivity of the reaction. Useful, environmentally friendly extraction procedure of decalactones (4a and 4b) based on hydrodistillation using a Deryng apparatus was developed. Both racemic lactones (4a and 4b), as well as their enantiomerically enriched isomers, were tested for feeding deterrent activity against Myzus persicae. The effect of these compounds on probing, feeding and settling behavior of M. persicae was studied in vivo. The deterrent activity of decalactones (4a and 4b) against aphids depended on the size of the lactone ring and the enantiomeric purity of the compounds. δ-Decalactone (4b) appeared inactive against M. persicae while γ-decalactone (4a) restrained aphid probing at ingestional phase. Only (–)-(S)-γ-decalactone (4a) had strong and durable (i.e. lasting for at least 24 hours) limiting effect, expressed at phloem level.     

Two sesquiterpene lactones of Calea ternifolia var. Calyculata

Chemical analysis of Calea ternifolia var. calyculata yielded the known sesquiterpene lactone calein A, as well as two new modified heliangolid     

Sesquiterpene lactones — insect feeding deterrents in Vernonia

Larval feeding tests were run to determine the preference of six species of Lepidoptera for two species of Vernonia which produce sesquiterpene lactones and one which has lost the ability to produce these bitter principles. Significant differences between the feeding preferences of the insect species were observed. Further feeding tests were run with a Vernonia leaf powder medium to determine how interspecific chemical differences influenced these preferences. The sesquiterpene lactone, glaucolide-A, was found to reduce larval feeding when incorporated in a Vernonia powder-agar medium. The amount of insect feeding was inversely proportional to the concentration of glaucolide-A in the medium.     

Resistance of Pteridium aquilinum to attack by non-adapted phytophagous insects

Fresh bracken Pteridium aquilinum L. Kühn or crude bracken extracts deterred 9 non-adapted phytophagous insect species from feeding or settling. Feeding deterrent activity to 5 out of 7 insect species was present in crude bracken extracts at all times over the growing season and was significantly highest in May. Sequential isolation and purification of deterrents indicated that the sesquiterpene pterosin F (6-chlorethyl-2,5,7-trimethyl-indan-1-one) occurred in sufficiently high concentrations in late May/early June bracken frond (24–28 mg/kg fresh wt) to be partially responsible for the deterrent effects of crude bracken extracts to two insect species. A number of other fractions had feeding deterrent activity, but these were not characterized or quantified.     

Terpenoids and bibenzyls of 25 liverwort Frullania species

Twenty-five Frullania species (liverworts) were chemically investigated. Fourteen species produce allergy-inducing sesquiterpene lactones. Eighteen species contain bibenzyls. The sesquiterpene lactones and bibenzyls are obtained as the major components and they are valuable chemosystematic markers of Frullania species. On the basis of their chemical constituents, Frullania species can be divided into five chemotypes: sesquiterpene lactone-bibenzyl type; sesquiterpene lactone type; bibenzyl type; monoterpene type and cyclocolorenone type.     

Sesquiterpene lactones and species relationships among the shrubby Ambrosia taxa

The sesquiterpene lactone chemistry, chromosome numbers and morphology of selected Sonoran Desert Ambrosia taxa are reported. The sesquiterpene lactone distribution correlates with morphologically defined species groups.     

Phytotoxic Effects and Phytochemical Fingerprinting of Hydrodistilled Oil,Enriched Fractions,and Isolated Compounds Obtained from Cryptocarya massoy (Oken) Kosterm. Bark

The hydrodistilled oil of Cryptocarya massoy bark was characterized by GC‐FID and GC/MS analyses, allowing the identification of unusual C₁₀ massoia lactone ( 3 , 56.2%), C₁₂ massoia lactone ( 4 , 16.5%), benzyl benzoate ( 1 , 12.7%), C₈ massoia lactone (3.4%), δ‐decalactone ( 5 , 1.5%), and benzyl salicylate ( 2 , 1.8%) as main constituents. The phytotoxic activities of the oil, three enriched fractions (lactone‐rich, ester‐rich, and sesquiterpene‐rich), and four constituents (compounds 1, 2, 5 , and δ‐dodecalactone ( 6 )) against Lycopersicon esculentum and Cucumis sativus seeds and seedlings were screened. At a concentration of 1000 μl/l, the essential oil and the massoia lactone‐rich fraction caused a complete inhibition of the germination of both seeds, and, when applied on tomato plantlets, they induced an 85 and 100% dieback, respectively. These performances exceeded those of the well‐known phytotoxic essential oils of Syzygium aromaticum and Cymbopogon citratus, already used in commercial products for the weed and pest management. The same substances were also evaluated against four phytopathogenic bacteria and ten phytopathogenic fungi, providing EC₅₀ values against the most susceptible strains in the 100–500 μl/l range for the essential oil and in the 10–50 μl/l range for compound 6 and the lactone‐rich fraction. The phytotoxic behavior was related mainly to massoia lactones and benzyl esters, while a greater amount of 6 may infer a good activity against some phytopathogenic fungi. Further investigations of these secondary metabolites are warranted, to evaluate their use as natural herbicides.     

Synergistic repellent activity of hot and cool thermal-sense compounds against two stored product insect pests

The repellent activities of one hot thermal-sense compound, vanillyl butyl ether (VBE), and two cool thermal-sense compounds, menthoxypropanediol (MPD) and (?)-isopulegol (IPG), against two stored product insects, Tribolium confusum and Liposcelis bostrychophila, were investigated. Such thermal-sense compounds affect mammals through transient receptor potential (TRP) channels, and both types of agonists (VBE and menthol) exhibited mutually inhibitory effects on mammalian TRPV1 and TRPM8 channels. Each compound exhibited repellent activity against both T. confusum and L. bostrychophila in a dose-dependent manner. Furthermore, synergistic effects were observed between VBE and MPD or IPG. The composition of TRP channels is different between mammals and insects. These results suggest that the use of thermal-sense compounds might serve as an alternative to essential oils in stored products protection.     

Behavioural responses of Oryzaephilus surinamensis, Tribolium castaneum and Tribolium confusum to naturally and artificially damaged durum wheat kernels

Observations on behavioural activity involved in the host selection by secondary pests of stored grains, Oryzaephilus surinamensis (Linnaeus), Tribolium castaneum (Herbst) and Tribolium confusum J. du Val, with respect to intact and mechanically or naturally damaged kernels are reported. Our results indicate that the attraction of secondary pests is facilitated by broken grain kernels, which resulted from either mechanical damage during harvesting and/or binning procedures, or the feeding activity of primary insect pests. Insect damaged kernels were more attractive to O. surinamensis, T. castaneum and T. confusum than whole kernels; in addition insect damaged kernels elicit more attractiveness than mechanically split kernels. The damage caused by primary pests, such as Rhyzopertha dominica (Fabricius) and Sitophilus oryzae (Linnaeus), on whole kernels may facilitate colonization by secondary pests, which continue damaging the cereals. O. surinamensis, T. castaneum and T. confusum utilize the grain volatile odours to distinguish whether the grain kernels of the stored cereals are damaged mechanically or by insects.     

Sesquiterpene lactones of Calea zacatechichi and C. urticifolia

Calea zacatechichi yielded the sesquiterpene lactone zexbrevin and a new analog, several analogs of neurolenin B including calein A, two analogs of budlein A and the flavones acacetin and O-methylacacetin. Calea urticifolia contained additional analogs of neurolenin B as well as a series of epoxidation products. Structures were established by spectrometric techniques. The results are contrasted with previous findings.