Most plant families are distinguished by characteristic secondary metabolites, which can function as putative defence against herbivores. However, many herbivorous insects of different orders can make use of these plant-synthesised compounds by ingesting and storing them in their body tissue or integument. Such sequestration of putatively unpalatable or toxic metabolites can enhance the insects’ own defence against enemies and may also be involved in reproductive behaviour. This review gives a comprehensive overview of all groups of secondary plant metabolites for which sequestration by insect herbivores belonging to different orders has been demonstrated. Sequestered compounds include various aromatic compounds, nitrogen-containing metabolites such as alkaloids, cyanogenic glycosides, glucosinolates and other sulphur-containing metabolites, and isoprenoids such as cardiac glycosides, cucurbitacins, iridoid glycosides and others. Sequestration of plant compounds has been investigated most in insects feeding or gathering on Apocynaceae s.l. (Apocynoideae, Asclepiaoideae), Aristolochiaceae, Asteraceae, Boraginaceae, Fabaceae and Plantaginaceae, but it also occurs for some gymnosperms and even lichens. In total, more than 250 insect species have been shown to sequester plant metabolites from at least 40 plant families. Sequestration predominates in the Coleoptera and Lepidoptera, but also occurs frequently in the orders Heteroptera, Hymenoptera, Orthoptera and Sternorrhyncha. Patterns of sequestration mechanisms for various compound classes and common or individual features occurring in different insect orders are highlighted. More research is needed to elucidate the specific transport mechanisms and the physiological processes of sequestration in various insect species.

Plant chemistry and insect sequestration.

The need for energy-efficient and environmentally friendly refrigeration, heat pumping, air conditioning, and thermal energy harvesting systems is currently more urgent than ever. Magnetocaloric energy conversion is among the best available alternatives for achieving these technological goals and has been the subject of substantial basic and applied research over the last two decades. The subject is strongly interdisciplinary, requiring proper understanding and efficient integration of knowledge in different specialized fields. This review article presents a historical and up-to-date account of the energy-related applications of magnetocaloric materials and information about their processing and magnetic fields, thermodynamics, heat transfer, and other relevant characteristics. The article also discusses the conceptual design of magnetocaloric refrigeration and power generation systems and some guidelines for future research in the field.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/aenm.201903741

Energy Applications of Magnetocaloric Materials

Plants are built of various specialized cell types that differ in their cell wall composition and structure. The cell walls of certain tissues (xylem, sclerenchyma) are characterized by the presence of the heterogeneous lignin polymer that plays an essential role in their physiology. This phenolic polymer is composed of different monomeric units – the monolignols – that are linked together by several covalent bonds. Numerous studies have shown that monolignol biosynthesis and polymerization to form lignin are tightly controlled in different cell types and tissues. However, our understanding of the genetic control of monolignol transport and polymerization remains incomplete, despite some recent promising results. This situation is made more complex since we know that monolignols or related compounds are sometimes produced in non-lignified tissues. In this review, we focus on some key steps of monolignol metabolism including polymerization, transport, and compartmentation. As well as being of fundamental interest, the quantity of lignin and its nature are also known to have a negative effect on the industrial processing of plant lignocellulose biomass. A more complete view of monolignol metabolism and the relationship that exists between lignin and other monolignol-derived compounds thereby appears essential if we wish to improve biomass quality.

/pdf/plant-cell-wall-lignification-and-monolignol-metabolism-22qruazakc.pdf

Plant cell wall lignification and monolignol metabolism

Plants and insect eggs: how do they affect each other?

The Plant Book, A Portable Dictionary of the Higher Plants.

Surfactants are amphipathic compounds containing both hydrophilic and hydrophobic groups, capable to lower the surface or interfacial tension. Considering the advantages of the use of biosurfactants produced by microorganisms, the aim of this paper was to develop and characterize a biosurfactant produced by Streptomyces sp. DPUA1559 isolated from lichens of the Amazon region. The microorganism was cultured in a mineral medium containing 1% residual frying soybean oil as the carbon source. The kinetics of biosurfactant production was accompanied by reducing the surface tension of the culture medium from 60 to values around 27.14 mN/m, and by the emulsification index, which showed the efficiency of the biosurfactant as an emulsifier of hydrophobic compounds. The yield of the isolated biosurfactant was 1.74 g/L, in addition to the excellent capability of reducing the surface tension (25.34 mN/m), as observed from the central composite rotational design when the biosurfactant was produced at pH 8.5 at 28°C. The critical micelle concentration of the biosurfactant was determined as 0.01 g/mL. The biosurfactant showed thermal and pH stability regarding the surface tension reduction, and tolerance under high salt concentrations. The isolated biosurfactant showed no toxicity to the micro-crustacean Artemia salina, and to the seeds of lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.). The biochemistry characterization of the biosurfactant showed a single protein band, an acid character and a molecular weight around 14.3 kDa, suggesting its glycoproteic nature. The results are promising for the industrial application of this new biosurfactant.

/pdf/production-and-characterization-of-a-biosurfactant-produced-3z3upwxeu7.pdf

Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region.

The essential oils from leaves, stems and fruits of Piper divaricatum were analyzed by GC-MS. The tissues showed high safrole content: leaves (98%), fruits (87%) and stems (83%), with yields of 2.0, 4.8 and 1.7%, respectively. This is a new alternative source

/pdf/chemical-composition-circadian-rhythm-and-antibacterial-1xaxep1ins.pdf

Chemical composition, circadian rhythm and antibacterial activity of essential oils of piper divaricatum: a new source of safrole

Tetranychus urticae Koch (Acari: Tetranychidae) is an economically important pest of agricultural and ornamental crops worldwide. It has been shown that many of natural plant-based pesticides have fewer side effects compared with synthetic chemicals. The essential oils of plants have been broadly studied for pest-control, including toxic and repellent effects, antifeedant, ovicidal, and other properties. Essential oils from stems, flowers, and leaves of Piper marginatum Jacq. were evaluated in the laboratory regarding their acaricidal potential against the two-spotted spider mite (T. urticae) and the results were compared with eugenol as a positive control. The oils were also evaluated with regard to the susceptibility of the natural enemy of T. urticae (Neoseiulus californicus McGregor). Based on LC50 estimates, oils from stems and flowers exhibited the same toxicity and differed significantly from the leaf oil with LC50 0.37, 0.56, and 3.77 μL L -1 , respectively. None of the oils tested exhibited toxicity greater than or equal to that of the positive control. The oil mortality rate was significantly lower for N. californicus (50% to 70%) than for T. urticae (> 95%). The P. marginatum oils also deterred oviposition. Among the chemical constituents tested, sesquiterpenes were more toxic with an LC50 of 2.89 μL L -1 than phenylpropanoids Z-asarone and E-asarone with LC50 6.64 and 8.51 μL L -1 , respectively. The acaricidal

/pdf/toxicity-of-essential-oils-of-piper-marginatum-jacq-against-49tyu1xlx6.pdf

Toxicity of essential oils of Piper marginatum Jacq. against Tetranychus urticae Koch and Neoseiulus californicus (McGregor)

It is now widely recognized that plant’s chemical composition is affected by both abiotic and biotic stress. This is the case of Mangifera indica leaves which respond very clearly to the damages caused by the grasshopper Tropidacris collaris and to mechanical damage by biosynthesizing several stress-related volatile compounds, mainly phenylpropanoids such as myristicin, dillapiole, eugenol and eugenol acetate. The identification of these phenylpropanoids in mango leaves in response to abiotic and biotic stress factors is a key step in the search for new natural pesticides, since phenylpropanoids have various biological activities, mainly insecticidal.

/pdf/biotic-and-abiotic-stress-induced-phenylpropanoids-in-leaves-16hhbliilx.pdf

Biotic and abiotic stress-induced phenylpropanoids in leaves of the mango (Mangifera indica L., Anacardiaceae)

Insect feeding preferences on Piperaceae species observed in Sao Paulo city, Brazil. Piperaceae species have been placed among the basal angiosperm and are adapted to a variety of habitats including moist forests, secondary vegetation and dry high lands. The major anatomical/morphology features are of small trees, vines, and shrubs for Piper species, while the epiphytic and succulent characteristics are predominant forms among Peperomia species. Their secondary chemistry can be mostly represented by amides, phenylpropanoids/lignoids, and chromenes in addition to a phletoria of biosynthetically mixed-origin secondary compounds. Although several amides and lignans are known as insecticides, several phytophagous insects, among which some considered pests of economic importance, have been observed feeding vigorously on Piperaceae species. Herein we describe the feeding preferences of fourteen phytophagous species of Coleoptera, Lepidoptera and Hemiptera over approximately fifty Piperaceae species observed in Sao Paulo, SP, Brazil, in a long-term basis.

http://www.scielo.br/pdf/rbent/v52n1/13.pdf

Clécio S. Ramos

Papers

Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region.

Chemical composition, circadian rhythm and antibacterial activity of essential oils of piper divaricatum: a new source of safrole

Toxicity of essential oils of Piper marginatum Jacq. against Tetranychus urticae Koch and Neoseiulus californicus (McGregor)

Biotic and abiotic stress-induced phenylpropanoids in leaves of the mango (Mangifera indica L., Anacardiaceae)

Insect feeding preferences on Piperaceae species observed in São Paulo city, Brazil