Effect of Common Variables in Rice Production on Rice Water Weevil Control1

Abstract

Five common variables in rice culture were investigated for their effeet on larval control of the rice water weevil Lissorhoptrus oryzophilus Kuschel by seed treatment. Soil types, methods of seeding, and storage of treated seed for as long as 5 months did not affect control appreciably. The ratio of aquatic grasses to rice plants and, at least indirectly, the rate of seeding influenced the level of control. As the ratio of aquatic grasses to rice plants increased, the level of control fell, apparently because some larvae that become established on aquatic grasses migrate during their development to nearby rice plants. The lateral movement of larvae was demonstrated in a field and insectary study.