Studies of planthopper species and their population fluctuation on cockspur in rice fields.
Planthopper egg masses were collected on Echinochloa crus-galli in rice fields in Hunan, China, and reared in the laboratory. From 6200 eggs placed on rice plants, 904 adults were obtained, of which 405 were Sogatella panicicola (Ishihara), 222 were Nilaparvata lugens (Stǻl), 139 were S. furcifera (Horv.) and 138 were Laodelphax striatella (Fall.). From 12 400 eggs placed on E. crus-galli, 3224 adults were obtained, of which 2188 were S. panicicola, 385 were N. lugens, 357 were L. striatella and 294 were S. furcifera. These 4 species fed and developed normally on both rice and E. crus-galli. S. panicicola showed a preference for E. crus-galli, and survival was greater on that species than on rice. N. lugens showed a preference for rice. The evidence suggested that populations of S. panicicola declined from the 1st to the 2nd rice crop, whereas those of N. lugens increased. While S. panicicola was the most abundant species in the samples from all the rice fields, the abundance of the other 3 species varied between sampling sites. Laboratory and field studies indicated that removal of E. crus-galli from rice field was of some importance in controlling planthoppers.