Fusaric acid : A secondary fungal metabolite that synergizes toxicity of cooccurring host allelochemicals to the corn earworm,Heliothis zea (Lepidoptera).

The ability of naturally occurring levels of theFusarium spp. fungal metabolite fusaric acid to synergize the toxicity of the allelochemicals gossypol, a saponin, and 6-methoxy-2-benzoxazolinone to larvae ofHeliothis zea (Boddie) was tested. Levels of fusaric acid comparable to those found near the fungus increased mortality ofH. zea to gossypol, the saponin, and 6-methoxy-2-benzoxazolinone, and decreased the development rate of surviving larvae exposed to gossypol and 6-methoxy-2-benzoxazolinone. Some effect was also noted for levels of fusaric acid found generally distributed throughout infected plants. The chemical properties of fusaric acid suggest that it synergizes the toxicity of the allelochemicals by inhibiting oxidative enzymes responsible for detoxification. Production of the biosynthetically simple fusaric acid may be a fungal strategy for conserving resources as compared to those fungi that produce biosynthetically complex toxins of their own.