Triterpene saponin hemi-biosynthesis of a leaf beetle’s (<Emphasis Type="Italic">Platyphora kollari</Emphasis>) defensive secretion

The adults of the leaf beetle Platyphora kollari (Chrysomelidae) are able to metabolise the oleanane triterpene β-amyrin (1) into the glycoside 3-O-β-d-glucopyranosyl-(1→4)-β-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 intermediate in the conversion of 1 into 2 and to check whether the sequestration of pentacyclic triterpenes is selective in favour of β-amyrin (1). To this end, adults of P. kollari were fed with Ipomoea batatas leaf disks painted with a solution of [2,2,3-²H₃]oleanolic acid or [2,2,3-²H₃]α-amyrin and the secretion of their defensive glands analysed by HPLC–ESIMS. The data presented in this work indicated that the first step of the transformation of β-amyrin (1) into the sequestered glycoside 2 is its oxidation into oleanolic acid (3) and that this conversion is selective but not specific in favour of β-amyrin (1).     

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

Summary The 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.     

Recycling plant wax constituents for chemical defense: hemi-biosynthesis of triterpene saponins from β-amyrin in a leaf beetle

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 -amyrin is a common constituent of leaf waxes, we hypothesized that these leaf beetles use this compound as a precursor to their oleanane glycosides. To test this hypothesis we first confirmed the presence of -amyrin in Ipomoea batatas, the food plant of Platyphora kollari. Next, adults of P. kollari were fed for 10 days with I. batatas leaf disks painted with a solution of [2,2,3-²H₃]-amyrin ([2,2,3-²H₃]-1). The secretion from their defensive glands was collected and analyzed by HPLC-ESIMS. The results demonstrated that the secretion of beetles fed with an amount of [2,2,3-²H₃]-amyrin corresponding to the quantity of unlabeled (natural) -amyrin present in the leaf disks contained on average 5.1% of [2,2,3-²H₃]-3-O--d-glucopyranosyl-(1-->4)--d-glucuronopyranosyl-hederagenin ([2,2,3-²H₃]-2), whereas the secretions of beetles fed with 10 times this amount of [2,2,3-²H₃]-amyrin contained on average 23.9% of [2,2,3-²H₃]-2. In both series of experiments, the percentage of labeled versus unlabeled triterpene glycoside in the secretion was positively correlated with the amount of deuterated -amyrin ingested. These results demonstrate for the first time that some leaf beetles are able to metabolize a widespread triterpenic constituent of leaf wax into more complex glycosides that are stored in their defensive glands.     

De novo biosynthesis of Δ3-Isoxazolin-5-one and 3-Nitropropanoic acid derivatives inChrysomela tremulae

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 than 100 times as many objects. A recent comprehensive compilation of published measurements provides the basis for a study indicating that quasar observations are not in good agreement with the original predictions of the Expanding Universe theory, but are well fit by the predictions of an alternative theory having fewer adjustable parameters.     

Sustainable livelihoods and people’s vulnerability in the face of coastal hazards

The present study investigates into the link between people’s vulnerability in the face of coastal hazards and sustainable livelihoods. It focuses on the town of Borongan in the Philippines and draws on questionnaire-based surveys and focus group discussions. This research shows that local fishermen are often compelled to go out fishing despite pending typhoon or storm surge to sustain the daily needs of their family. Its also demonstrates that the capacity of these people to protect themselves from the threat is constrained by poor and fragile livelihoods. In the event of a crisis, the study argues that people resort to a range of adjustments on their daily life which is rooted in the strength and diversity of their livelihoods. To reduce people’s vulnerability and enhance capacities to face coastal hazards, the study fosters Community-Based Disaster Risk Reduction with special emphasis to sustainable livelihoods.     

Academic publishing in disaster risk reduction: past,present, and future

Nowadays there are approximately 80 Anglophone journals that deal primarily with disaster risk reduction (DRR) and allied fields. This large array signals a sustained, if uneven, growth in DRR scholarship but also competition between the offerings of different publishers and institutions. The purpose of this article is first to summarise the development of academic publishing on DRR from its early beginnings to the present day. The paper then evaluates the current state of publishing in this field and discusses possible future trends. Next, it identifies some possible opportunities, challenges, expectations, and commitments for journal editors both within DRR and academia more broadly, including those that refer to changes in the use of terminology, the relentless increase in the number of papers submitted, the expansion and dangers of predatory journals, different peer review models, open access versus paywalls, citations and bibliography metrics, academic social networks, and copyright and distribution issues.     

Chemical defense in Platyphora kollari Baly and Leptinotarsa behrensi Harold (Coleoptera: Chrysomelidae). Hypotheses on the origin and evolution of leaf beetles toxins

Summary. The defensive secretions of Platyphora kollari beetles (Chrysomelidae) from Brazil contained one oleanene glycoside. This was identified as 3-O-g-D-glucopyranosyl-(l̆)-g-D-glucuronopyranosyl-hederagenin (8), by a combination of 1D and 2D NMR methods (COSY, HMQC, MBC) and SIMS. There were also several amino acid derivatives, including the known non-protein amino acid (Z)-2-amino-3,5-hexadienoic acid (1), the new dipeptide L-n-glutamyl-2-amino-(3Z)-hexenoic acid (4), ethanolamine (7), and a mixture of phosphatidylcholines. Compounds 1 and 7 have already been identified in several leaf beetle taxa. Secretions of Leptinotarsa behrensi contained as major triterpene glycoside 3-O-g-d-glucopyranosyl-(l̅)-g-d-glucuronopyranosyl-oleanolic acid-28-O-g-d-glucopyranoside (9), already isolated from Platyphora opima. Although the host plants of these beetles were devoid of these triterpene glycosides, g-amyrin was shown to be present in three plants on which different species of triterpene-producing chrysomelids had been fed (Mikania micrantha, Ipomoea batatas and Convolvulus arvensis). This suggests that these insects are able to use g-amyrin from their food plant as a precursor to their oleanolic- and hydroxyoleanolic acid glycosides. The distribution of toxins already identified in leaf beetles suggests that amino acid derivatives could be a plesiomorphic character, considering their wide distribution, whereas the secretion of triterpene saponins, probably derived from ubiquitous plant triterpenes, could be an apomorphic character shared by some Doryphorina. The secretion of cardenolides derived from ubiquitous plant phytosterols would be another apomorphic character shared by other Doryphorina and Chrysolinina.     

An ecdysteroid (22-acetyl-20-hydroxyecdysone) from the defense gland secretion of an insect: <Emphasis Type="Italic">Chrysolina carnifex</Emphasis> (Coleoptera: Chrysomelidae)

Summary. 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 of steroid production in similar glands of closely related leaf beetles.     

Disaster studies inside out

Disaster studies is faced with a fascinating anomaly: frequently it claims to be critical and innovative, as suggested by the so‐called vulnerability paradigm that emerged more than 40 years ago, yet often it is perpetuating some of the core and problematic tenets of the hazard paradigm that we were asked to challenge initially. This paper interrogates why such an anomaly persists. In so doing, it employs Antonio Gramsci's concept of hegemony to unpack why disaster studies is still dominated by Western epistemologies and scholars that perpetuate an orientalist view of disasters. Ultimately, it suggests a research agenda for the 40 years to come, which builds on the importance of local researchers analysing local disasters using local epistemologies, especially in the non‐Western world. Such subaltern disaster studies are to be fuelled by increasing consciousness of the need to resist the hegemony of Western scholarship and to relocate disaster studies within the realm of its original political agenda.