Feeding deterrants insect

Methyl 2-pyrrole carboxylate was transformed in two steps into an N-pyrrolylalanine derivative which was converted into a pyrrolo[l,2-a]pyr-azine after heating under reflux in toluene. Five subsequent steps led to peramine (Scheme 50), a principal insect feeding deterrent, from Acremo-nium iolli (88CC978). 

Resistance of plants to herbivorous animals is determined in many cases by the presence in plant tissues of secondary metabolites that may cause feeding deterrence or toxocity to the animal. Insects cause damage to cereals, decreasing grain production. Development of varieties resistant to insects is then desirable for improving cereal productivity. 

Azadirachtin has several effects on a number of economically important species of insect pests, including feeding deterrency. 

Examples of Flavonoids Acting as Feeding Deterrents for Insects... 

Sutherland, O.R.W. et al.. Insect feeding deterrent activity of phytoalexin isoflavonoids, Biochem. Syst. Ecol, 8, 73, 1980. 

Russell, G.B. et al., Vestitol a phytoalexin with insect feeding-deterrent activity, J. Chem. Ecol, 4, 571, 1978. 

The behavior of Insects In selecting a host plant for food and shelter is affected by a wide array of physical and chemical stimuli. Chemicals that play a role in resistance mechanisms may interfere with an Insect s orientation, inhibit feeding, or deter ovipositlon. Most of the known mechanisms of resistance involve feeding deterrents, but the most vulnerable phase of the Insect life cycle may prove to be ovipositlon. Environmental factors may influence the ability... 

A number of diterpenes are known to be active against herbivores ( ). The diterpenes abietic, dehydroabietic, 12-methoxy-abietic, sandaracopimaric, and isopimaric acid serve as feeding deterrents for the larch sawfly, Pristiphora erichsonii in single needles from new shoots of tamarack (Larix laricina) (133). The larvae of this insect do eat tufted needles on short shoots of the same trees. 

Often related insect species are not all sensitive to a particular allomone. For example, juglone is a feeding deterrent to the smaller European elm bark beetle (Scolytus multistriatus) but not to the closely related hickory bark beetle (Scolytus quadrispinosus) (106,107). 

Isolation of Phytoecdysones as Insect Ecdysis Inhibitors and Feeding Deterrents... 

O. nubilalis diets (Ewete etal., 1996b). We have also isolated nine triterpenes from bark of Lansium domesticum, collected in Borneo (Omar, 2000). These compounds, called lansiolides, including lansiolic acid (Fig. 1.4), have insect feeding-deterrent activity as well as antimalarial activity. 

The third factor is that PAs are extremely effective broad-spectrum feeding deterrents. Numerous species spanning 11 plant families have made use of this attribute (Hartmann and Ober, 2000). Arctiids and other PA-pharmocophagous insects have converted antiherbivore defenses to antipredator defenses. We know little about the mechanisms by which PAs affect their unpalatability. It seems unlikely that the long-term cytotoxic and genotoxic effects of PAs are relevant to their fast-acting deterrency. Recent work has indicated that some PAs bind to acetylcholine receptors (Schmeller et al., 1997) however, further study is required to understand the mode of action of the PAs. 

Russell GB, Sutherland ORW, Hutchins RFN, Christmas PE. 1978. Yestitol A phytoalexin with insect feeding deterrent activity. J Chem Ecology 4 571-579. 

Peramine (352) is a pyrrole alkaloid identified as a major insect feeding deterrent isolated from perennial ryegrass infected with the entophyte Acre-monium lolii. Due to the interesting heterocyclic ring system and biological activity, the synthesis of peramine is attractive [230],... 

Antiherbivory roles of metabolites have been well documented.9,25,26 Proksch31 reported that lichens produced secondary metabolites that acted as feeding deterrents which protected them from animal consumption. Several insects appeared to selectively avoid the medullary region, which contained most of the lichen metabolites, grazing primarily on the algal layer.25... 

As reviewed by Williams (43), ecdysone has been isolated from more than 10 species of conifers, 20 ferns, and 30 flowering plants (out of 1000 species surveyed). A total of 28 different plant ecdysones are known, the most ubiquitous being /3-ecdysone. The ecological significance of /3-ecdysone in plants is unclear. It is not toxic when orally ingested (as feeding larvae would obtain it from a food plant), but there is some evidence that it could be a feeding deterrent in concentrations as low as 1 ppb. Perhaps it serves as a steroid base for other compounds once it is in an insect s metabolic system. 

Trihydroxy- - Mentha piperita (Famiaceae) insect feeding deterrent]... 

---