Agronomy and Horticulture Department
Date of this Version
The ashgray blister beetle, Epicauta fabricii (LeConte); the striped blister beetle, E. vittala (F.) ; and the margined blister beetle, E. pestifera Werner collected in the field from plants of sweetclover low in coumarin content, fed preferentially in the Iaboratory on low-coumarin leaves when offered a choice between leaves from highand low-coumarin plants. The black blister beetle, E. pennsylvanica (De Geer) , not known to feed 011 sweetclover foliage, also fed preferentially in the laboratory on leaves from low-coumarin plants, although the rate of feeding was much slower than for the other species. By using appropriate genotypes of sweetclover and controlling the type of light to which the plants were exposed, it was possible to offer the beetles choices among leaves differing greatly in their content of specific coumarin-related compounds. Both cis-o-hydroxycinnamic acid (cis-o-HCA) glucoside and coumarin (the lactone form of cis-o-HCA) were strong feeding deterrents: trans-HCA glucoside had no significant deterring effect,
Published in the Journal of Economic Entomology (1972) 65: 1,632-1,635.