|Lin, Sisi - IOWA STATE UNIVERSITY|
|Hart, Elwood - IOWA STATE UNIVERSITY|
Submitted to: Journal of Experientia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 21, 1998
Publication Date: N/A
Interpretive Summary: Poplar trees are grown throughout the world for short rotation production of woody pulp materials which are used in paper manufacturing. Poplars are easy to grow and breed, and most natural populations have excellent growth characteristics. One limiting factor for poplar crops is the severe defoliation from feeding activity of the cottonwood leaf beetle. Beetle feeding often results in stunted growth of the trees and thus lowers the recovery of wood pulp. Leaf surface chemicals of poplars are known to be involved in the stimulation of beetle feeding on foliage. These compounds were identified in this study as alpha-tocopherylquinone and several long chain hydrocarbon alcohols. Combined, these compounds synergistically stimulate cotton leaf beetle feeding in laboratory feeding bioassays. Variation occurs in the leaf surface chemicals of selected poplar trees and our studies show that beetles do not feed on trees when alpha tocopherylquinone is absent from the leaf surface. Through breeding selection we can remove the feeding stimulants, improve poplar resistance to cottonwood leaf beetles, and increase the availability of woody pulp materials for paper manufacturing. Use of beetle resistant trees also will result in less need for insecticide treatments and lower rates of pollution from pesticides.
Technical Abstract: Leaf surface chemicals from a cottonwood leaf beetle-preferred poplar clone, "Eugenei" (Populus deltoides x Populus nigra), induce feeding in the adult cottonwood leaf beetle, Chrysomela scripta Fabr. (Coleoptera: Chrysomelidae). The feeding stimulants were isolated and identified as n-beheryl alcohol (C 22), n-lignoceryl alcohol (C 24), n-hexacosanol (C 26), n-octacosanol (C 28), n-triacontanol (C 30) and a-tocopherylquinone (2-(3-hydroxy-3, 7, 11, 15-tetramethyl-hexadecyl)-3, 5, 6-trimethyl-<1, 4>benzoquinone, a-TQ). It is the first time that a-TQ has been reported as a feeding stimulant for an insect. Fatty alcohols or a-TQ alone do not induce beetle feeding significantly, but a mixture of alcohols and a-TQ synergistically stimulates beetle feeding. The role of these feeding stimulants in insect feeding behaviors and possible use in a pest management program is discussed.