Désiré Daloze

Chemical defence in chrysomelid larvae and adults

Abstract The defensive secreation of several species of chrosomelid larvae and adults have been analyzed. Salicyaldehyde and some already known methylcyclopentanoid monoterpenes have been identified in the larvae. In the adults of the tribe Phaedonini, two isoxazolin-5-one derivatives (8 and 9) were isolate and their structures determined. The chemical defence of chrysomelid beetles is briefly reviewed with emphasis on chemataxonomy and ecological significance.

Chemical defences in leaf beetles and their larvae: The ecological, evolutionary and taxonomic significance

Abstract The chemical defences of the Chrysomelinae are reviewed. Defensive glandular secretions have evolved independently in larvae and adults, and faster than the morphology of the glands. Both characters are used in a phylogenetic study of the Chrysomelini, disclosing suprageneric affinities. First, a close relationship between the Chrysomelina and Phratora is proposed. Secondly, Leptinotarsa and Gonioctena are probably more closely related to the Chrysolinina than to the Chrysomelina and Phratora . The qualitative and quantitative composition of larval and adult secretions sometimes differs between geographically isolated populations of the same species, which are therefore probably genetically distinct. The host plant shows an influence which explains discrepancies between the current classification and the chemical nature of the secretions. Some beetles sequester secondary plant metabolites or use them as precursors for their own defences. The original biosynthetic pathway has been lost in these species. Other factors which could affect the chemical diversity of the secretions are discussed: random events such as neutral mutations and genetic drift, conditioning or adaptation of predators to specific defensive mixtures, and the diversity of potential predators. The latter could help to explain the divergence in the chemical nature of the larval and adult secretions. The volatile irritants produced by the larvae are well suited to repel small arthropods, such as ants, whereas poisons associated with aposematic coloration in the adults could be directed against small vertebrates, such as birds.

Chemotaxonomy of Agelas (Porifera : Demospongiae)

The secondary metabolite content of four different species of Agelas (Porifera) from the West Indies has been studied. All the compounds isolated are already known metabolites whose identification was confirmed by comparison of their spectral properties with those reported in the literature. They pertain to two different classes of compounds: terpenoids and pyrrole-2-carboxylic acid derivatives. The chemotaxonomic value of these secondary metabolites has been evaluated. Their distribution amongst the Porifera, as well as that of isocyanide derivatives, suggests a close relationship between the Agelasidae, the Axinellidae and the Halichondriidae.

Chemical defence in chrysomelid eggs and neonate larvae

ABSTRACT. Eggs and neonate larvae of chrysomelid beetles (sub‐tribes Chrysomelina and Phyllodectina) were investigated for the presence of defensive substances.

Ladybird defence alkaloids: Structural, chemotaxonomic and biosynthetic aspects (Col.: Coccinellidae)

SummaryThe defensive mechanisms which protect ladybird beetles (Coccinellidae) against predators are reviewed. Besides behavioural mechanisms, such as thanatosis and reflex bleeding, chemical defence mechanisms are playing a prevalent role. Indeed, ladybirds are protected not only by their smell, but also by repulsive alkaloids, most of which are considered to be of autogenous origin. In a few cases, dietarily-acquired substances are also involved. Particular emphasis is laid on the repellent alkaloids which are contained in the haemolymph of many species. The structures of 34 nitrogen-containing compounds isolated so far are presented, and their distribution within the family is discussed in the light of the most widely accepted classification of these beetles. To conclude, the mode of release of the alkaloids, their variation through the life cycle and their repellent and toxic properties are discussed, as well as the few biosynthetic data yet available.

Two new guanidine alkaloids from the Mediterranean sponge Crambe crambe

Crambine A (1) and B (2) were isolated from the Mediterranean sponge Crambe crambe. Their structures were determined mainly by extensive NMR 2D experiments at 600 MHz.

Absolute configuration of the solenopsins, venom alkaloids of the fire ants

Abstract An effective and practical procedure has been developed that allows the assignment of the absolute configuration of solenopsins from diverse origins us

Applications of artificial intelligence for chemical inference—XXI: Chemical studies of marine invertebrates—XVII. The computer-assisted identification of [+]-palustrol in the marine organism Cespitularia sp., aff. subviridis☆☆☆

Abstract In order to demonstrate the power utility of the interactive computer program CONGEN, 5 an example describing its use in the identification of the tricyclic sesquiterpene alcohol, [+]-palustrol, in extracts of a marine Xeniid ( Cespitularia sp., aff subviridis ) is provided. The rotation of [+]-palustrol further supports the remarkable antipodal relationiship between sesquiterpenes from marine Coelenterates and their corresponding terrestrial forms. 6

A new family of tricyclic alkaloids from Myrmicaria ants

Abstract The poison gland secretion of the African ant, Myrmicaria opaciventris , contains three families of new alkaloids. These alkaloids are represented by a “monomeric” type with 15 carbon atoms in a row forming derivatives of indolizines, while the two other families are “dimers” and “trimers” with 30 and 45 carbon atoms, respectively. The major constituents of the low molecular weight alkaloids are identified to be pyrrolo[2,1,5-cd]indolizines, highly dominated by l-ethyl-3,4,41,5,6,7-hexahydro-2-((1 Z )-1-propenyl)-pyrrolo[2,1,5-cd]indolizine, myrmicarin 215A . The higher molecular weight components show complex oligocyclic structures, which are closely related to the pyrroloindolizines. The alkaloid pattern shows a high degree of intraspecific variation.

Production of cardiac glycosides by chrysomelid beetles and larvae

Cardenolides were looked for in 17 chrysomelid beetles belonging to 11 genera from three subfamilies, and they were found only inChrysolina andChrysochloa species (Chrysomelinae, Chrysolinini). The food plants of these insects are not known to produce cardenolides. TheChrysochloa and mostChrysolina species secrete a complex mixture of cardenolides, butChrysolina didymata secretes a single compound, andChrysolina carnifex, none. Several quantitative and perhaps qualitative differences were observed in the patterns of cardenolides produced by far distant populations of bothChrysolina polita andC. herbacea, collected in either France and Belgium, or Greece. These differences remain constant from one generation to the other, whatever the food plant is, and appear to be genetic. InC. polita from Greece, the pattern is unchanged after four generations bred in the laboratory onMentha ×villosa, which is known to be without cardenolides. In adults, the cardenolides are released with the secretion of the pronotal and elytral defensive glands, but in the larvae which lack the defensive glands, cardenolides are also produced. The total amount of cardenolides and the complexity of their mixture increases through the life cycle of the insects. The six main cardenolides secreted byC. coerulans were identified as: sarmentogenin, periplogenin, bipindogenin, and their corresponding xylosides.C. didymata secretes only sarmentogenin.