Host plant iridoid-based chemical defense of an aphid,Acyrthosiphon nipponicus,against ladybird beetles

A Rubiaceae-feeding aphid,Acyrthosiphon nipponicus, is seldom attacked by the ladybird beetle,Harmonia axyridis. A potent deterrent against the beetle was isolated from the aphid and identified as paederoside, an iridoid glycoside originating in the aphid's host,Paederia scandens. The iridoid content was as high as 2% of the intact body weight, and a large portion was found in the cornicle secretion.     

Some chemical bases for gypsy moth,Lymantria dispar,larval rejection of green ash,Fraxinus pennsylvanica,foliage as food

Green ash is one of the few tree species rejected as food by larvae of the generalist gypsy moth,Lymantria dispar L. (Lepidoptera: Lymantriidae). Such rejection is based especially on chemicals present in green ash foliage. The gypsy moth larval feeding-inhibitory activity is contained in the ethyl acetate extractables of green ash foliage. Three representative columnchromatographed fractions of the extractables contained antifeedant activity. Individual fractions showed weaker antifeedant activity compared to the total ethyl acetate extractables. Acid hydrolysis of the extractables destroyed antifeedant activity and yielded feeding stimulant activity at higher concentrations. The aqueous extractables were not feeding-inhibitory. Compounds in the green ash extractables were separated by TLC, HPLC, CC, and GC.     

Use of chemical variation and predation as plant defenses byEncelia farinosa against a specialist herbivore

Larvae of the monophagous herbivore,Trirhabda geminata, selectively eat particular plants and plant parts of its natural host,Encelia farinosa. Measurements of leaf damage and larval positions on branches through time support this observation. Time-lapse movie photography revealed that larvae are sufficiently mobile to search most of a plant in a 48-hr period and that aggregations were the result of larval activity and not directly the result of oviposition. Experiments withT. geminata larvae on artificial diets containing a range of natural concentrations of chemical extracts fromE. farinosa leaves showed that the larvae grew significantly slower and had a lower overall survivorship at the high concentration. Combining the results of all choice tests, larvae appeared unable to distinguish between high- and low-concentration agar diets. Considered individually, larval preferences for natural production concentrations changed as the season progressed. Early-season larvae preferred low-concentration leaves, while late-season larvae preferred high-concentrations. Measurements of chemical and nitrogen content of leaves selected by larvae in the field confirmed this pattern. Percent parasitism in field-collected larvae increased with season as the larval population decreased. This combination of slowed growth and increasing parasitism and predation is a putative defense strategy ofEncelia farinosa to prevent adaptation by a specialist herbivore to the total range of compounds elaborated.     

Integration of a chemical process model in a power plant modelling tool for the simulation of an amine based CO2 scrubber

Post-combustion is considered among the different options for CO₂ capture as the most mature available technology. All major components of the CO₂ absorption/desorption process are commercially available but at a smaller scale, and they are not integrated and optimized for the application in power plants. Therefore, it is still to be demonstrated that this process is a viable option for the capture of CO₂ at power plants. The amine scrubbing process with standard solvents is highly energy demanding due to solvent regeneration and CO₂ compression. This is a significant energy sink for the power plant and efficiency can be reduced up to 16%-points. In order to minimise the energy penalty, complete integration and optimization of the capture and the power plant processes are necessary.Simulations of the power plant cycle and the amine scrubbing system have been performed with specialized software. The results of the integration are discussed.