A PRELIMINARY STUDY ON THE ROOT-ATTACKING CHRYSOMELID,DONACIA LENZI SCHONFELDT

Hu,S.Y.;Yu,S.T.;CHANG,S.C.Kiangsi Agricultural Research Institute

The Root-attacking chrysomelid, Donacia lenzi Schonfeldt is one of theharmful rice pests in Kiangsi.There is one generation per year. It overwintersin larval stage in the mud about 24-27 cm. deep. In spring, they begin to riseup to attack the rice roots. Pupation takes place at the middle of May andsometimes lasts to August. Afterwards the adult emerges. Females lay eggs onthe host leaves of six different species which usually located just beneath thewater surface. The young larvae creep down the soil after hatching. A total of 13 species of plants is recorded as larval hosts. Among them,4 species are also fed by the adults and 6 species are used by the females todeposit eggs. However, most eggs are laid on the leaves of Potamogetonpolygonifolius Pourr. Based upon the study of its life history and habits, some control measuresare mentioned in this paper, and according to results obtained from thelaboratory experiments, tobacco stem is the most effective to kill the larvae.