Induction of Furano-terpenoids in Sweet Potato Roots by the Larval Components of the Sweet Potato Weevils

When sweet potato root tissues were infested by the larvae of sweet potato weevil, Cylas formicarius and West Indian sweet potato weevil, Euscepes postfasciatus, furano-terpenoids and coumarins were produced in brown necrotic layer formed during the infestation.

The larval homogenates of both weevils also induced in the tissue the production of furano-terpenoids and coumarins, as well as the formation of necrotic layer. The larval homogenate of sweet potato weevil induced also ethylene formation, the marker of injury in the tissue. Investigations on the furano-terponoid inducing factor demonstrated that the factor was 20 mm KCl-soluble, non-dialyzable, acetone-precipitable, (NH₄)₂SO₄-precipitable, heat-unstable, passing through Sephadex G–25 column without sieving and partially inactivated by pronase, indicating that the factor was a high molecular weight compound, perhaps of a proteinacious property. It is likely that the factor causes injury or death to sweet potato root tissue, leading to the formation of ethylene and necrotic layer, and then to production of furano-terpenoids and coumarins.