Antifeedants compounds

Herbivores have evolved many offensive adaptations that counteract the defensive adaptations of plants, including antifeeding compounds (Rhoades, 1985). 

It was toxic to the pink bollworm at 0.005% and to the bollworm and the tobacco budworm at 0.15% in artificial diets. Esters (C10-C12) were also toxic to the insects as sprays. Matricaria ester was also shown to be a potent insect antifeedant compound to these insects (115). 

An antifeedant compound that deters insects from eating food crops has the gross structure shown below. Some of the NMR signals that can clearly be made out are also given. Since NMR coupling constants are clearly useless in assigning the stereochemistry, how would you set about it ... 

Cyanobacterial blooms pose a public health risk and may have adverse effects on marine life (fish, turtles) that accidentally consumes them. The production of toxins or of antifeedant compounds, particularly in cyanobacterial strains that are slow growing can lead to rapid bloom production in areas of high herbivory, for example on tropical coral reefs.8... 

While much work has been done by innumerable workers trying to extract, purify, and identify various components of plants known to be relatively free from attack by insects, most of these materials have fallen in the category of true repellents rather than antifeeding compounds, and none have shown promise for practical production and usage. 

Several seasons of field testing have shown a number of advantages in the use of the antifeeding approach to insect control. First, it is selective. Antifeeding compounds affect only pests which feed on the crop protected. Parasites and predators which walk over the treated foliage or feed on the affected insects are not killed, as with conventional insecticides. Honey bees and other pollinators are not affected by toxic deposits. 

Another advantage of antifeeding compounds is their low toxicity in comparison with many of today s insecticides. 24,055 itself has an acute rat oral LD50 of 510 mg. per kg., and 36-day chronic feeding studies showed no effect on rats resulting from daily ingestion of up to 1250 p.p.m. in the diet (4). 

As with other methods of pest control, there are limitations in the use of the antifeeding method. Foremost is that, in general, only surface-feeding insects are controlled. This is not unexpected, since antifeeding compounds apparently work by taste, and insects which do not feed on the surface, with its residue of material, are not affected. 

While many chewing insects are controlled by 24,055, even here there are limitations. If the insect attacks by penetrating the surface and feeding inside, control is not obtained. Pests which feed inside the fruit, such as the cotton bollworm, the corn borer, and the plum curculio—all chewing insects—take such a small amount of the treated surface before eating their way into the interior of the fruit, that control is difficult with an antifeeding compound. 

Antifeeding compound 24,055 was successful against chewing insects which fed on a surface that could be covered with the com-... 

The discovery of antifeeding compounds which prevent chewing insects from feeding on a crop may offer promise it is too early to assess the significance of this development. 

The methanol extract of the bark of Phellodendron amurense was shown to possess strong antifeedant activity against the paper/wood termite pest Reticulitermes speralus. Partitioning and chromatography of the extract afforded four active antifeedant compounds, one of which was berberine [215],... 

In an attempt to overcome the limitation that only surface feeding chewing insects can be controlled by the known antifeedant compounds, Jermy and coworkers (Jermy and Matolcsy, 1967 Matolcsy et al. 1968) investigated the antifeedant activity of some substituted phenoxyethanols and phenoxyacetic acids which do not affect plant growth and which are known to possess systemic properties. 2,4,6-Trichlorophenoxyethanol (6) and 2,4,6-trichlorophenoxyacetic acid (7) have shown the highest antifeeding activity both under laboratory and field conditions. 

Wilfordin, tryptofordin and celangulin (Fig. 14) are antifeedant compounds obtained from extracts of the Celastraceae species Maytenus rigida [78], Trypterigium wilfordii [79] and Celastrus angulatus [77, 80], respectively, and as some products isolated from South American species have similar structural characteristics, they too have been assayed. 

Fig. 14. Structure of Some Antifeedant Compounds from the Celastraceae...

USE Antifeeding compounds for insect pest control non -systemic fungicide. 

Rotenone (35) has a long history as a commercial botanical insecticide [65], although almost neglected today. However, it has been reported as one of the best natural antifeedant compounds ever tested against storage pests [66]. 

However, in recent years, food attractants (kairomones) have found only infrequent applications. On the other hand, antifeedant compounds with very high activity, notably azadirachtin from neem... 

Antifeedant Compounds Insecticidal and Nematicidal Activity Diterpenes with Juvenile Hormone Activity Diterpenes That Prevent Reproduction in Insects Trail-Marking Pheromones Diterpenes from Marine Plants Sweeteners Medicinal Properties Antitumor Compounds Sesterterpenes Biosynthesis Biological Activity References... 

Many of the antifeedant compounds discussed above have insecticidal activity as well. Moreover, other diterpenes are toxic to insects and nematodes when consumed. Ryanodine (81), from Ryania speciosa (Flacourtiaceae) and several related species, is unique in that its insecticidal activity was discovered as a part of a search for new insecticides (Crosby, 1971). The toxic principle, ryanodine, is a diterpene esteri-fied to a pyrrole-2-carboxylic acid (Crosby, 1971). Ryanodine inhibits cardiomuscular calcium transport (Croteau and Johnson, 1985). 

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