Interactions between Biotypes of the Brown Planthopper and Rice Varieties

Abstract

Behaviors of four biotypes of the brown planthopper on rice varieties with different resistance genes were investigated. Results showed that the behavioral and physiological responses of a biotype to rice varieties having the same resistance gene on which the biotype was developed, in general, resemble the response to susceptible varieties. The biotypes developed from the varieties with a stronger antibiotic factor to the insect showed more virulent to different vane-ties than those from a weaker one. Histological studies of the feeding sites in the tissues of resistant varieties revealed that no mechanical barrier to the insect's feeding involved. However, any biotype put on unsuitable host plants showed restless and changed their feeding sites frequently, and fed less from resistant varieties. Genetic studies on the ability of biotypes to survive on resistant varieties showed that the virulence of biotype was controlled by polygenes, and dominance effects were the most important factor in determining the inability of biotype to survive on resistant varieties. A simulated study indicated that rotation and mixed planting of plants with different resistance genes will be effective in lowing the rate of development of virulent biotypes.