Entomology, Department of


Date of this Version



Korean J. Plant Prot. 25(1) : 37-40 (1986)



We surveyed the IRRI farm to determine the extent of parasitization of yellow stemborer egg masses. The egg masses were randomly collected at weekly intervals from July to October 1984 from rice fields, 15-20 days after transplanting, and brought to the laboratory for collection of emerging parasites. Three species of hymenopterous parasitoids—Tetrasticus schoenobii, Telenomus rowani, and Trichogramma japonicum—were found from 700 egg masses.

We introduced a method to calculate percent parasitism as based on parasite biology and behaviour. Among the three species, the combination of T. rowani and T. japonicum was the highest multiparasitization of yellow stem borer egg masses, and T. rowani, a solitary parasite had the highest number based on immature and adult stages counted. However, T. schoenobii may be the most efficient parasite because two to four host eggs are needed to complete the larval period, and it took 10-14 days for one generation.

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