Antifeedant activities, plant compounds

Diterpenoids have a wide range of biological activities. Their role in plant-insect interactions, both as antifeedants and growth inhibitors, is reviewed. Four ent-kauranes, kaur-16-en-19-oic acid, (-)-kauran-l > -ol, 15 t-hydroxy-(-)-kaur-16-en-19-oic acid, and 17-hydroxy-(-)-kaur-15-en-19-oic acid, have recently been isolated from the leaves of Solidago nemoralis.These compounds were found to have antifeedant activity against Trirhabda canadensis. 

Furocoumarins such as isopimpinellin, bergapten, and kokusagin have antifeedant activity against Spodoptera litura (54). A number of similar compounds from umbelliferous plants have been demonstrated to be active antifeedants against Spodoptera litura. Periplaneta americana. Musca domestica. Blattela germani ca, and Stylopyga rhombifolia (98). 

Plant parts other than seeds have been less well studied and little attention has been placed on insecticidal modes of action of the defenses of the neotropical Meliaceae. Our study of the insect growth-reducing activity of 50 extracts of bark, leaf and wood of Central American Meliaceae showed the potent effect of these extracts against lepidopteran larvae and the potential for isolation of bioactive compounds from alarge number of these species. Extracts from the genera Trichilia and Cedrela (Xie etal., 1994 Ewete etal., 1996a Wheeler etal., 2001) show exceptional activity. Trichilia americana extracts have strong antifeedant activity to Spodoptera... 

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. 

Escoubas, P. Lajide, L. Mizutani, J. Insecticidal and antifeedant activities of plant compounds potential leads for novel pesticides., American Chemical Scociety Washington, DC, 1994 Vol. 551, pp 162-71. 

Products isolated from plants of the Celastraceae family have showed insecticidal and antifeedant activities, as discussed earlier. The compounds reported belong to the agarofuran sesquiterpene-type and sesquiterpene pyridine-type alkaloids. Nevertheless, the only description of insecticidal activity of quinone methides found is from Avilla et al [102], Despite the fact that the compounds assayed were known the... 

Regulation of the biosynthesis of secondary metabolites cannot be seen as separate from the role of these products for the plant. However, in most cases this role is not known. In the case of C. roseus an antifeedant activity against Spodoptora larvae has been reported for vinblastine and catharan-thine 49). A nematocidal effect has been reported for serpentine 50). Antifeedant activity against Spodoptera caterpillars for C. roseus leaf extracts has been described as well 49,51). Luijendijk et al. 52,53) found that besides alkaloids, also nonpolar compounds are involved in the antifeedant... 

As long as mankind continues to cultivate and grow plants for food, feed, and fiber, crops will be threatened by various enemies and agents such as insects, fungi, and bacteria. Prevention and control of insect pests and plant diseases will remain an important objective of agrochemical research. In this study, the isolation and structure determination of several compounds showing insect antifeedant activity and antifungal activity from Peru plants are presented. 

Tokunaga T, Takada N, Ueda M (2004) Mechanism of antifeedant activity of plumbagin, a compound concerning the chemical defense in carnivorous plant Tetrahedron Lett 45 7115-7119 Trapp S, Croteau R (2001) Defensive resin biosynthesis in conifers. Annu Rev Plant Physiol Plant Mol Biol 52 689-724... 

Many triterpenes also have anti herbivore activity. In general, those which are highly oxygenated seem to be more active in this regard M). The role of cardiac glycosides, insects and their predators has been reviewed (91-94). A number of metabolically altered triterpenes from the Rutaceae, Meliaceae and Simaroubaceae are antifeedants. Extracts of neem tree seeds (Azadirachta indica. Meliaceae) were shown to be repellent to a number of insects when applied to various crop plants at low concentrations. The probable active compound is tetranortriter-pene, azadirachtin (9 ). This compound from the leaves and fruits... 

Most acetylenic compounds in plants are derived from meta-bolically altered fatty acids. These often are active in plant-insect relationships. 8-cis-Dihydromatricaria acid is also found in the defensive secretion of the soldier beetle (Chaulioqnathus 1econtei) (125), and has subsequently been shown to have anti-feedant properties against Phidippus spp. (jumping spiders) (126). As previously mentioned matricaria ester has antifeedant properties to the pink bollworm, bollworm and tobacco budworm (115). 

In spite of the many studies on isolation, activity, and synthesis of natural antifeedants, the number of compounds commercially available remains low, often due to their cost of isolation, availability of the plant source, or low persistence in field conditions. To overcome these drawbacks, much research is conducted on structure—activity relationships (SAR). The rationale behind these studies is to discover the correlation between biological activity and chemical structure and to draw from that optimum structures having both the activity, stability, and selectivity for maximum feeding deterrence.4 5 SAR are much used in drug design6 and have been applied to insecticides.7... 

Tliis study describes the isolation and bioassay against insects of six compounds from the Peruvian plant Alchornea trlplinervia. The compounds anthranilic acid, cinnamic acid, and camphor showed significant inhibition of the growth of the tobacco budworm. Anthranilic acid, gentisic acid, senecioic acid, cinnamic acid, and cinnamaldehyde demonstrated low to moderate activity in the boll weevil antifeedant bioassay. Cinnamaldehyde, a constituent of the spice cinnamon, showed the highest level of inhibition to boll weevil feeding. 

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