The bionomics of the cottonwood leaf beetle, Chrysomela scripta Fab., on tissue culture hybrid poplars

Abstract

Tissue culture methods are applied to poplars of the Aigeiros group in attempts to overcome premature decline thought to be associated with viral infections. Hybrid selections from such cultures outplanted in 1975 at the F. G. Wilson Nursery in Boscobel, Wisconsin subsequently were severely infested by the Cottonwood Leaf Beetle, Chrysomela scripta Fab. Beetle populations built up rapidly in spring 1977 and severe defoliation occurred; an average of 45% of the terminal buds were destroyed and 73 percent of the tips of a preferred clone were fed upon. Younger foliage appeared preferred and certain clones sustained more feeding in field and laboratory studies. Plants receiving greater amounts of overhead irrigation were least defoliated. Rapid increases in the numbers of the insect in Wisconsin are reflected in the following facts. The Cottonwood Leaf Beetle has a rapid life cycle (19 days at 27?C). Consequently, the insect undergoes 4-5 generations per year in Wisconsin where it exhibits a high fecundity of approximately 510 eggs. Finally, because of the larval defensive secretion, salicylaldehyde, the insect has few natural enemies; mainly predatory pentatomids on larvae and adults, and Shizonotus latus Walker, a pupal parasite.

Parent Publication

• Proceedings of the 13th Lake States Forest Tree Improvement Conference, August 1977.

Citation

Burkot, T.R.; Benjamin, D.M. 1977. The bionomics of the cottonwood leaf beetle, Chrysomela scripta Fab., on tissue culture hybrid poplars. In: Proceedings of the Thirteenth Lake States Forest Tree Improvement Conference; Gen. Tech. Rep. NC-50. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 131-135