Written Paper

Egg parasites of Scirpophaga incertulas (Walker) in Sri Lanka  [1987]

Ahangama, D. Gilstrop, F.E. (Peradeniya Univ. (Sri Lanka))


The yellow stemborer (YSB) Scirpophaga invertulas (Walker) were studied in Mar and Jul 1982 at the Dryzone Agricultural Research Station, Maha Illuppalarma, Sri Lanka. After transplanting, experimental plots were covered with mesh cages. Two weeks after transplanting, plots were exposed for YSB oviposition. The experiment was repeated four times in two seasons. Hatched egg masses were collected on day four, remaining egg masses were collected on day eight and held in glass vials in the laboratory. Number of parasites emerging from each egg mass was recorded. Then, egg masses were soaked in 5% HCl and separated into individual eggs and number of hatched eggs, unenclosed dead larvae, and unemerged parasites recorded. Parasites were sent to the Commonwealth Institute of Entomology for identification. Telenomus sp. and Tetrastichus schoenobii Ferriere were the only egg parasites obtained from 193 egg masses (1,070 eggs) of S. incertulas. Although Telenomus sp. caused a higher percentage of parasitization than T. schoenobii in all four generations (S. incertulas completes two generations each cropping season in Sri Lanka), the difference was not significant.