Date: 3/31/99

Time: 8:30

Type: Symposium

Number: 221

Novel anti-insect fungal metabolites

*P. Dowd, USDA-ARS NCAUR, Peoria, IL 61604
Contact e-mail: dowdpf@mail.ncaur.usda.gov

Antiinsectan fungal metabolites have been discovered by a variety of strategies. Essentially random screening or specifically looking at particular genera has yielded some useful compounds. Compounds with known toxicity to vertebrates often are also toxic to insects. Other novel compounds have been discovered by examining long term fungal survival structures, insect pathogens, or plant endophytes. A number of different compounds with various postsulated modes of action have been identified. Compounds acting on protein synthesis include aflatoxins, trichothecenes, alpha-amanitin, and the proteins restrictocin and hirsutellin. Ochratoxin A and citrinin interfere with nitrogen excretion. Neuroactive compounds include muscimol, territrems, penitrems and paspalinines and their analogs. Destruxins and efrapeptins inhibit ATPase. Pyripyropene A may interfere with cholesterol metabolism, and griseofulvin appears to interfere with porphyrin synthesis. E-64 and analogs inhibit thiol proteases in Coleoptera. Sclerotiamide appears to intefere with hydrostatic presssure regulation. Several other compounds, while of relatively low toxicity, are capable of interacting synergistically by inhibiting detoxifying enzymes and defense-related enzymes. Many of the fungal metabolites with activity against insects are most active orally or by injection. So far, commercial interest has been limited because no fungal compound with high enough topical activity combined with high selectivity towards insects has been discovered yet. Nevertheless, active compounds already identified may still serve as lead structures for the development of future insecticides.

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