Damages caused by larvae and adults of Diabrotica speciosa (Coleoptera : Chrysomelidae) in corn

Diabrotica speciosa (Germar, 1824) is traditionally a polyphagous pest duri ng the adult phase although with some preference for bean and soybean leave s. In the past years, however, the larval phase of this chrysomelid achieve d the pest status likewise other species of the genus in the USA causing se vere damages to the root system of corn. The aim of this research was to ev aluate the damages caused by different population levels of D. speciosa to corn roots and by adults to corn, soybean, bean and rice leaves. A signific ant decrease in the dry weight of corn roots, in the dry weight of the uppe r part, and in plant height in comparison with the control plant was observ ed even in small larvae population densities. The economic threshold level was less than 40 larvae per plant. The adults had significant preference fo r bean and soybean leaves while corn and rice were less consumed.