Jacques Pasteels

Université Libre de Bruxelles | ULB · Department of Biology of Organisms (DBO)

Due to its fundamental role in shaping host selection behavior, we have analyzed the chemosensory repertoire of Chrysomela lapponica. This specialized leaf beetle evolved distinct populations which shifted from the ancestral host plant, willow (Salix sp., Salicaceae), to birch (Betula rotundifolia, Betulaceae). We identified 114 chemosensory candid...

This review reports on natural compounds that derive from the isoxazolinone ring as well as the 3-nitropropanoic acid (3-NPA) moiety. These structural elements occur in compounds that have been identified in plants, insects, bacteria and fungi. In particular, plants belonging to the family of legumes produce such compounds. In the case of insects,...

Charidotella ambita offers a unique opportunity for unambiguously locating its gold reflector by comparing the structure of reflecting and non-reflecting cuticle of the elytron and pronotum. Using light microscopy and TEM, the reflector was located underneath the macrofiber endocuticle just above the epidermis. The reflector is a multilayer compris...

Juveniles of the leaf beetles in subtribe Chrysomelina have efficient defense strategies against predators. When disturbed, they transiently expose volatile deterrents in large droplets from nine pairs of defensive glands on their back. Here, we report on an additional line of defense consisting of the non-volatile isoxazolin-5-one glucoside and it...

A summary of literature, documented observations and field studies finds evidence that mothers actively defend offspring in at least eight species and three genera of Neotropical Chrysomelinae associated with two host plant families. Reports on three Doryphora species reveal that all are oviparous and feed on vines in the Apocyanaceae. Mothers in t...

Larvae of the Chrysomelina species Phaedon cochleariae, Hydrothassa marginella, Phratora vulgatissima, Gastrophysa viridula, Gastrophysa atrocyanea, Gastrophysa cyanea and Gastrophysa polygoni produce the iridoid chrysomelidial (1) to defend themselves against predators. Feeding experiments with a deuterated precursor ([(2) H(5) ]8-hydroxygeraniol...

We conducted a phylogeographic study on the cold-adapted leaf beetle Chrysomela lapponica, that feeds on willow or birch, by sampling several populations throughout most of the geographic distribution of the species, and by sequencing for each individual one mitochondrial and two nuclear DNA fragments. Patterns of DNA sequence variation from the mi...

Chrysomelid leaf beetles use chemical defenses to overcome predatory attack and microbial infestation. Larvae of Chrysomela lapponica that feed on willow sequester plant-derived salicin and other leaf alcohol glucosides, which are modified in their defensive glands to bioactive compounds. Salicin is converted into salicylaldehyde by a consecutive a...

Glandular chemical defence relying on the action of salicylaldehyde is characteristic for Chrysomela leaf beetle larvae. The salicylaldehyde precursor salicin, sequestered from salicaceous host plants, is deglucosylated and the aglycon further oxidized by a salicyl alcohol oxidase (SAO) to the respective aldehyde. SAOs, key enzymes in salicin-based...

The Dufour's gland secretion of C. scutellaris contains a series of C23 long chain derivatives characterized by the presence of a cross-conjugated dienone linked to either a primary acetate, an aldehyde, or a carboxylic acid function. These compounds further differ from each other by the degree of unsaturation and (or) the position of an isolated d...

The administration of sodium [1-14C] and [2-14C] acetate, L-[U-14C] glutamic acid, &([a-z]+);-amino [U-14C] butyric acid, L-[U-14C] ornithine hydrochloride, and [1,4-14C] putrescine dihydrochloride to Tetraponera sp. ants resulted in the formation, for each feeding experiment, of labelled tetraponerine-8 (2). The distribution of radioactivity into...

Larvae of Chrysomela lapponica (Coleoptera: Chrysomelidae) sequester characteristic O-glucosides from the leaves of their food plants, namely Betula and/or Salix The present study focuses on birch-feeding larvae of C. lapponica from the Altai region in East Kazakhstan. As in other sequestering leaf beetle larvae, the compounds are transported intac...

The nature of the cosmic redshift is one of the most fundamental questions in modern science. Hubble's discovery of the apparent Expansion of the Universe is derived from obsevations on a small number of galaxies at very low redshifts. Today, quasar redshits have a range more than 1000 times greater than those in Hubble's sample, and represent more...

Pheromones play a crucial role in the ecology of dispersal and foraging in termites. Sex-pairing pheromones possess a double role of long-range attraction to unite sexual partners and a short-range or contact attraction to maintain the pair during the tandem behaviour. Sex-pairing pheromones most often comprise a single compound capable of elicitin...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The composition of the defence secretions of six species of chrysomelid beetles (Chrysolina polita, C. americana, C. grossa, C. herbacea, C. fastuosa, and Oreina gloriosa) belonging to the sub-tribe Chrysolinina has been investigated. Two known cardenolide aglycones, sarmentogenin (1) and oleandrigenin (23), and fourteen new cardiac glycosides (7–2...

Four new 1 (15),8 (19)-trinervitadiene derivatives have been isolated from nasute termite soldiers from Papua-New Guinea and their structures determined on the basis of their spectral properties. They have been identified as 9β-acetoxy-2β,3α-dihydroxy-1 (15),8 (19)-trinervitadiene (1), 2β,3α,9α, 13β-tetraacetoxy-1 (15),8 (19)-trinervitadiene (2) an...

Two new 1 (15), 8 (19)-trinervitadiene derivatives have been isolated from the frontal secretion of an undescribed species of nasute termite (Nasutitermes sp PNG (F)). They have been identified as 20-acetoxy-2β, 3α-dihydroxy-1(15), 8 (19)-trinervitadiene (1) and 9β, 20-diacetoxy-2β, 3α-dihydroxy-1 (15), 8 (19)-trinervitadiene (2) on the basis of th...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The following collection of papers was presented during a Symposium, organized at the initiative of the Jean-Marie Delwart Foundation. The aim was to generate brain storming on chemical communication sensu lato among renowned experts coming from different horizons, plant biology being their common link. The Symposium was multidisciplinary and inclu...

Sex ratio data were collected and orphaning experiments carried out in the New Guinea giant cocoa termite, Neotermes papua. The sex ratio of the alates tends to be slightly female-biased, whereas males represent on average about 60% of the pseudergates and soldiers. This might represent a rudimentary form of sex specialization in the production of...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The larval defenses of chrysomeline leaf beetles comprise components that are either synthesized de novo or sequestered from their food plants. Both biosynthetic modes are based on glucosides that serve as substrates and forms of transport. The defensive glands import the compounds through highly selective glucoside transporters from a circulating...

The larval defenses of chrysomeline leaf beetles comprise components that are either synthesized de novo or sequestered from their food plants. Both biosynthetic modes are based on glucosides that serve as substrates and forms of transport. The defensive glands import the compounds through highly selective glucoside transporters from a circulating...

Dendroctonus micans, recently arrived in the French Massif Central has reached outbreak level in many spruce stands in the Haute Loire, Ardèche and Lozère, causing important damage. An effort is being made to introduce the specific predator, Rhizophagus grandis, which, in regions where D. micans is endemic, is held to be one of the principal agents...

Few studies to date have investigated the impact of Pleistocene climatic oscillations on the genetic diversity of cold-adapted species. We focus on the geographic distribution of genetic diversity in a Euro-Siberian boreo-montane leaf beetle, Gonioctena pallida. We present the molecular variation from three independent gene fragments over the entir...

The feeding preferences of Phratora (= Phyllodecta ) vitellinae towards different Populus clones, previously studied by greenhouse experiments and field observations, are estimated here by choice experiments on leaf discs, in the laboratory. The following clones are tested: ‘Ghoy 1’, ‘Gaver’, ‘Robusta vert’, ‘Fritzy Pauley’, ‘Columbia River’, and ‘...

In the larval chrysomelines the de novo synthesis of monoterpenoids (iridoids) is believed to represent the ancestral state in the evolution of chemical defenses. Here we demonstrate that the iridoid producing larvae of Plagiodera versicolora and Phratora laticollis have the potential to sequester precursors from food. In nature, iridoids may even...

Genetic differentiation within and among isolated populations of the arctic-alpine leaf beetle, Chrysomela lapponica L. (Coleoptera: Chrysomelidae), specialized on either Salix L. (Salicaceae) or Betula L. (Betulaceae) species, was assessed by F-statistics analysis at seven allozyme loci. Beetles were collected on Salix spp. in lowland Finland (fou...

Salicyl alcohol oxidase is an extracellular enzyme that occurs in glandular reservoirs of chrysomelid leaf beetle larvae and catalyzes the formation of salicylaldehyde, a volatile deterrent used by the larvae against predators. Salicyl alcohol is the hydrolysis product of salicin, a plant-derived precursor taken up by the beetle larvae from the lea...

The present study reports a case where the survey of morphological and mitochondrial DNA variation among populations of a species complex of leaf beetle, the Gonioctena variabilis complex, has lead to the identification of a hybrid zone between two species of the complex in Southern Spain. The complex is divided into four species distributed around...

The uptake of hypericin from the foliage of Hypericum perforatum by four species of adult chrysomelid beetles, Chrysolina brunsvicensis, C. geminata, C. hyperici and C. varians, was investigated under laboratory conditions. In no species were detectable levels of hypericin passed from the larval to the pupal or adult stages. The total amount of hyp...

Accurate descriptions of feeding habits are essential to understanding the evolution of dietary preferences and the high levels of diversification within the Chrysomelidae. Both primary observations and summaries suggest that the cassidine beetle tribe, Cephaloleiini, is a species-rich group of feeding specialists on monocot hosts. However, accurat...

Only one species of the termitophile staphylinid tribe Trichopseniini, Prorhinopsenius neotermitis, associated with Neotermes spp. (Kalotermitidae), was previously known from New Guinea and adjacent islands. Further collections from colonies of the Rhinotermitidae genera Schedorhinotermes and Parrhinotermes yielded 11 species, all new to science, i...

The tortoise beetle Charidotella egregia is able to modify the structural color of its cuticle reversibly, when disturbed by stressful external events. After field observations, measurements of the optical properties in the two main stable color states and scanning electron microscope and transmission electron microscope investigations, a physical...

The adults of the leaf beetle Platyphora kollari (Chrysomelidae) are able to metabolise the oleanane triterpene beta-amyrin (1) into the glycoside 3-O-beta-D: -glucopyranosyl-(1-->4)-beta-D: -glucuronopyranosyl-hederagenin (2) that is stored in their defensive glands. The aim of this study was to test the hypothesis that oleanolic acid (3) is an in...

Feeding larvae of Chrysomela lapponica (Coleoptera: Chrysomelidae) acquire characteristic O-glucosides from the leaves of their food plants. The glucosides are selectively channeled from the gut to the defensive gland. Subsequent enzymatic transformations generate a blend of different defensive compounds, e.g., salicylaldehyde and two series of 2-m...

Chemicals, which mediate the interactions between aphids, ladybirds and ants, are reviewed. Special emphasis is laid on autogenous and plant-derived chemical defence in aphids and ladybirds. Evidences for chemical cues used during foraging and oviposition in ladybirds are assessed. Possible mutualistic interaction between plants and the third troph...

Cantharenone 1, a new diterpene structurally related to the prenylbisabolane skeleton, has been isolated from the beetle Cantharis livida (Cantharidae). Its structure has been determined on the basis of its spectral properties. This is the first report of such a type of diterpenoid from an insect.

Hyperaspine (1a), isolated from the European Coccinellidae Hyperaspis campestris, isthe first representative of a new type of ladybird alkaloids having a 3-oxaquinolizidine skeleton. A new total synthesis of (±)-hyperaspine starting from protected piperidin-4-one has been achieved. The absolute configuration of the natural alkaloid was unequivocall...

Methanolic extracts of soldiers of Nasutitermes guayanae and N. surinamensis have been shown to contain complex mixtures of diterpenes and monoterpenes. Eighteen diterpenes have been isolated and identified; twelve of them are previously known nasute termite diterpenes, while six are new trinervitene diterpenes. 2alpha,9beta-Dihydroxy-3beta,8beta-o...

Hyperaspine (1a), isolated from the European Coccinellidae Hyperaspis campestris, is the first representative of a new type of ladybird alkaloids having a 3-oxaquinolizidine skeleton. A new total synthesis of (+/-)-hyperaspine starting from protected piperidin-4-one has been achieved. The absolute configuration of the natural alkaloid was unequivoc...

Stenotarsol (1), a new terpenoid alcohol, has been isolated from the beetle Stenotarsus subtilis (Endomychidae). Its structure has been determined on the basis of its spectral properties. Compound 1 represents a new type of terpene skeleton and is the first secondary metabolite reported so far from this family of beetles.

Chrysomeline larvae respond to disturbance and attack by everting dorsal glandular reservoirs, which release defensive secretions. The ancestral defense is based on the de novo synthesis of monoterpene iridoids. The catabolization of the host-plant O-glucoside salicin into salicylaldehyde is a character state that evolved later in two distinct line...

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Sets out to disclose patterns allowing reasonable predictions as to which arthropods will be chemically defended, against whom, when, where, and how. The patchy distribution of chemical defence within the arthropods is noted, eg. common in Heteroptera, absent or rare in Ephemeroptera and Diptera. Within Orders, too, there is imbalance: in Coleopter...

Many beetle and ant species owe their protection against predators to the presence of defensive compounds in their hemolymph or in specialized exocrine glands. A growing number of studies devoted to the elucidation of the biosynthetic pathways used by the insects to produce these compounds have been reported in recent years. An overview of these st...

Several species of Doryphorina leaf beetles from Central- and South America produce oleanane triterpene glycosides in their defensive glands. The presence of pentacyclic triterpenes in insects is intriguing since they lack the key enzymes necessary to synthesize these compounds. Since beta-amyrin is a common constituent of leaf waxes, we hypothesiz...

22-Acetyl-20-hydroxyecdysone was identified as a major component in the secretion of elytral and pronotal glands of Chrysolina carnifex, at an estimated concentration of 1.5 x 10-1 M. This unexpected high concentration of an ecdysteroid in an exocrine secretion of an insect is discussed in terms of its potential defensive function, and in the light...

The cover picture shows the ladybird Coccinella septempunctata (Coccinellidae) which, when molested, emits hemolymph droplets at its joints. This mechanism, known as reflex bleeding, constitutes an efficient protection against predators due to the presence of bitter-tasting alkaloids (e.g. coccinelline). Autogenous production of coccinelline throug...

Leaf beetles of the genus Platyphora, feeding on plant species containing pyrrolizidine alkaloids of the lycopsamine type, not only sequester these alkaloids and concentrate them in their exocrine defensive secretions, but also specifically process the plant acquired alkaloids. Using P. boucardi as subject, three mechanisms were studied: (i). utili...

Several neotropical leaf-beetles of the genus Platyphora ingest and specifically metabolize plant acquired pyrrolizidine alkaloids (PAs) of the lycopsamine type (e.g., rinderine or intermedine) and enrich the processed alkaloids in their exocrine defensive secretions. In contrast to the related palaearctic leaf beetles of the genus Oreina, which ab...

Sequestration and processing of pyrrolizidine alkaloids (PAs) by leaf beetles of the genus Platyphora were investigated. Tracer experiments with labeled alkaloids were performed with P. eucosma feeding on Koanophyllon panamense (Asteraceae, tribe Eupatorieae). P. eucosma catalyzes the same reactions previously demonstrated for P. boucardi specializ...

The Dufour gland of the African ant Crematogaster nigriceps contains a mixture of at least eight 1-heptadec(en)yl- and 1-nonadec(en)yl-1,3,5-trihydroxycyclohexane derivatives, the mono-unsaturated components being the major ones (about 65%). They are accompanied by small amounts of (Z,Z)-dienic derivatives (<10%). The structures, the relative and a...

Larvae of a number of chrysomelid leaf beetles sequester phenol glucosides such as salicin from their food plants, i.e. Salix and Populus spp. Salicin is hydrolyzed in the glandular reservoir of the defensive glands. The resulting salicyl alcohol (saligenin) is oxidized by an extracellular oxidase. The product salicylaldehyde accumulates as major d...