Aphid antifeedants

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... 

Pyridine azomethine insecticides contain a pyridine and an azomethine group. Pymetro-zine is the only member of this class. It is a highly selective antifeeding insecticide for control of aphids and whiteflies on vegetables, potatoes, citrus, fruits, hops, and ornamentals. 

The tetracyclic triterpenoid quassin is an antifeedant to the aphid Myzus persicae [15], and the limonoids azadirachtins from Azadirachta indica are also potent insect antifeedants [13]. 

Compound 23 also interfered with the settling behavior of the aphid M. persicae an efficient plant virus transmitter. Choice assays showed that this compound had antifeedant potencies slightly lower than the positive control famesol (table 7). Furthermore, the electronic monitorization of the aphid s probing behavior (EPG) showed that 23 reduced the number of intracellular penetrations (table 8) [34], This is an important parameter when considering the transmission of non-persistent plant viruses by this insect [35],... 

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]. 

In aphids, pymetrozine (1) inhibits feeding immediately after application, resulting in death by starvation without producing visible neurotoxic effects. No repellent or antifeedant effects were observed that could explain the inhibition of feeding. 

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... 

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