Aphid antifeedant activity

A series of quassinoids was tested for antifeedant activity against the aphid Myzus persicae (Hemiptera, Aphididae) as shown in Table 7. Isobrucein-B (5), brucein-B (75), brucein-C (76), glaucarubinone (77), and quassin (78) decreased feeding at concentrations <0.05% and isobrucein-A (79) was effective at 0.01%. However, only quassin (78) showed no phytotoxic effects. Therefore, Polonsky et al. concluded that quassin (78) was the most promising compound for further development [28]. 

Grindelane normal-labdanes 185 and 188 isolated from Grindelia, Chryso-thamnus, Solidago, and Haplopappus displayed significant antifeedant activity against the Colorado potato beetle (440) and the aphid Schizaphis graminum... 

The abundant natural compound linalool (3) is an attractant for the Colorado potato beetle (CPB), Leptinotarsa decemlineata. Two isomeric derivatives of linalool, (Z)-5-(1.5-dimethylhex-4-enyldiene)-dihydrofuran-2-one (4) and ( )-5-(1.5-dimethylhex-4-enyldiene)-dihydrofuran-2-one (5), were synthesized and were found to be moderate antifeedants against the CPB. A lactone derived from linalool strongly affected the properties of the original compound linalool, which is an attractant to the CPB. A similar effect is seen with the activity of either linalool (3) or 4-isobutyl-5-isopropyl-5-methyl-dihydrofuran-2-one (6) to aphids. Compared to linalool, the lactone reduced the total time the aphid spent on the leaf.16... 

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