Below-ground herbivory by a Noctuid larva on Tanacetum huronense.

Abstract

Tanacetum huronense (Lake Huron tansy) is a threatened plant endemic to the sand dunes of the Great Lakes. A below-ground herbivore was discovered feeding on the plant's rhizome. The herbivore was a cutworm moth caterpillar from the family Noctuidae. This study demonstrated that tansies occurring in lower density plots were more likely to be attacked by the cutworm. The reproductive state of the plant was not correlated to attack rate. Grazed plants did have smaller maximum leaf lengths than ungrazed plants. Grazed flowering plants also had signficantly smaller rhizome diamters than ungrazed plants. Experimentally simulated herbivory demonstrate no damage induced mortality and indicated that rhizome damage may in fact stimulate greater growth.