Naturalne i syntetyczne antyfidanty owadów : cz.2

Antifeedants, chemicals which prevent insects from feeding, have been at the centre of interest of researchers for the last forty years. Most of them are of natural origin., being a part of plant protective system. Antifeedants of followin groups: diterpenoids (including degraded limonoids), triterpenoids, alkaloids, lignanes, flavonoids, and coumarine derivatives are presented here. The most numerous group of diterpenoids are cleradanes, isolated mainly from plants of Teucrium genus. Clerodin, ajugarin and jodrellin are the best known members of this group. The second large group are limonoids, belonging to tetranortriterpenes, found mainly in plants of Meliaceae and Rutaceae family. The main compound of this group is azadirachtin, isolated from Azadirachta indica (Meliaceae). Not being harmful to mammals, it displays strong feedingdeterrent activity towards a great number of insect species. Huge amount of limonoids has beeb found in plants. Advanced studies on the synthesis and correlation between chemical structures and biological activity for clerodanes and limonoids have been carried out. Synthetic fragments of natural antifeedants, which exhibit activity comparable to the natural compounds, are also presented . Degraded limonoids are the natural and synthetic diterpenoid compounds, the structures of which are fragments of natural limonoids. Great interes has been taken in this group for the last 10 years. Some alkaloids are also presented here, as they are one of the first known insect antifeedants. They are active towards different insect species, including stored grain pests. The last presented group are coumarine derivatives, active against Spodoptera litura. In this case studies on structure-activity correlation were carried out as well . The perception of antifeedants at the sensory level may involve different mechanisms. Feeding deterrents may stimulate specialized receptors tuned to other compounds and thus alter the sensory code. There is also a hypothesis, based on electrophysiological data, that the impulses from different receptors are not received independently, but in a comlexed form. Modification of this neural code changes insect's behaviour. On the basis of biological data it has been postulated that polyphagous insets are less sensitive to antifeedants than more specialised species.