Entomology, Department of


Date of this Version



Journal of Economic Entomology 73:1 (1980), pp. 35–40.

doi: 10.1093/jee/73.1.35


Copyright ©1980 Entomological Society of America. Published by Oxford University Press. Used by permission.


Techniques to quantify the feeding activity of Nilaparvata lugens (Stål) on rice varieties as based on honeydew excretion are described, and their potential as a bioassay for biotype identification are discussed. Honeydew, excreted on filter paper, was stained with ninhydrin and quantified by measuring the area (mm2) or by weighing. Results were satisfactory but the methods were extremely tedious. Volumetric measurement of honeydew with micropipettes was less sensitive. The color intensity of one μliter honeydew streaked on filter paper and treated with 0.001% ninhydrin was determined with a Fujiox Densitometer. The method was relatively simple and rapid and was sufficiently precise for biotype identification as based on differential feeding activity.