Insect ecdysis inhibitors

Figure 15. 3-Deacetylazadirachtinol, a Potent Insect Ecdysis Inhibitor Isolated from the Seeds of Azadirachta indica (57)...

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

Kubo, I. and J. Klocke, Insect ecdysis inhibitors, in Natural Resistance of Plants to Pests (M. B. Green and P. A. Hedin, eds.), ACS Symposium Series 296, 206-219, American Chemical Society, Washington, DC, 1986. 

Another natural product which was Isolated from A. indica and found to have potent ecdysis Inhibitory activity Is deacetyl-azadlrachtlnol (Figure 8) (42). The biological activity of deacetylazadlrachtlnol fed in artificial diet to H. virescens Is shown In Table IV. Although deacetylazadlrachtlnol was about 2.5-fold less active than was azadlrachtln as an Insect growth Inhibitor (EC50 - 0.17 and 0.07 ppm, respectively), the two compounds had the same ecdysis inhibitory activity (EI50 "... 

Chitin Synthesis Inhibitors. These are insect growth regulators that prevent the formation of the insect chitinous exoskeleton and thus produce a critical biochemical lesion during hatching, ecdysis, or pupation (44). These complex biochemical and physiological processes are unique to arthropods therefore, the benzoyl phenyl ureas are highly specific insecticides (44). 

These molecules were shown to be potent inhibitors of chitinase, an enzyme involved in the ecdysis of many insects and crustaceans, whose inhibitors are supposed to control the settlement of barnacles and, therefore, could have a potential application as antifouling agents. Unfortunately, no data are available in the literature about cytotoxic, immunosuppressive, or antibacterial activities of styloguanidines and, thus, a comparison with the potently bioactive congeners palau amines is not possible. 

Earlier work investigated growth effects from monoterpenoids dosed topically on last-instar larvae of the house fly (19). Development and metamorphosis failures occurred with several compounds. Cineole was the most active inhibitor of pupal eclosion (40% inhibition at a dose of 10 /lig/insect) and of imaginal differentiation, within those uneclosed pupae. Camphene, eugenol, and a-pinene were also active. Inhibition of pupal ecdysis was highest in insects treated with camphene, although carvone and several others were also effective. 

---