Effects of Rice Plant Density, Rice Water Weevil (Coleoptera: Curculionidae) Damage to Rice, and Aquatic Weeds on Aster Leafhopper (Homoptera: Cicadellidae) Density

Abstract

In California rice fields, high densities of the aster leafhopper, Macrosteles fascifrons Stål, usually are associated with a sparse rice stand, rice plants damaged by the rice water weevil, Lissorhoptrus oryzophilus Kuschel, and abundant aquatic weed growth. Results of field experiments showed that aquatic weeds had a direct impact on aster leafhopper densities. Several of these weeds, particularly Monochoria vaginalis (Bunn. f.) Presl. and Sagittaria montevidensis Cham. and Schlecht., were preferred to rice for oviposition. A sparse rice stand or weevil-damaged plants can indirectly affect aster leafhopper populations by reducing the ability of rice to compete with weeds. The result is increased weed growth which favors the buildup of aster leafhoppers.