Tetrastichus schoenobii Ferriere

Hymenoptera: Chalcidoidea: Eulophidae: Tetrastichinae

Body bright metallic blue-green or shining green with bluish lustre. Antenna brown except for yellowish scape, 8-segmented with three-segmented funicle and club, scape not reaching front ocellus. In female, funicle with all three segments equally long; in male, funicle four-segmented, I segment shorter than rest, scape with a narrow and elongate sensory organ, nearly as long as scape. Mesoscutum with well developed notaular lines, median furrow very weak, nearly obliterated anteriorly. Scutellum with a pair of conspicuous submedian lines / furrows. Submarginal vein of fore wing with a single seta. Abdomen elongate oval, apically pointed in female, not broader than mesosoma (thorax), ovipositor only slightly exserted. Legs more or less yellowish, except base of anterior coxae and hind coxae dark green, tarsal apices brownish; tarsi four-segmented in all pairs of legs. Propodeal spiracle bound by an inverted Y-shaped carina.

 
 Thorax

  Adult female on yellow stem borer eggmass
 Adult female, dorsal view
    Adult, dorsal view
 Adult - lateral view
  Rice yellow stem borer egg mass with emergence holes of T. schoenobii

Tetrastichus schoenobii has been recorded as a primary parasitoid of shoot borers of rice and sugarcane, particularly Scirpophaga incertulas, S. excerptalis, S. innotata, Chilo suppressalis, C. infuscatellus (all Pyralidae), and also Sesamia inferens and Spodoptera mauritia (Noctuidae). Trichomalopsis apanteloctena (Crawford) (=Eupteromalus parnarae Gahan) is a hyperparasitoid of T. schoenobii.

Tetrastichus schoenobii is a predator-cum-parasitoid of rice yellow stem borer eggs because it attacks several eggs during its development. Several wasps may parasitize an egg mass of stem borers. Each female parasitoid lays one egg in each stem borer egg. It can produce 10 to 60 offspring. Egg incubation takes 1 to 2 days. Larval development takes place inside the egg host. Once the egg is consumed, the larval parasite moves out from the egg and locates another egg host for its development. Several reports suggest that T. schoenobii is the most important egg parasitoid of rice yellow stem borer along with scelionids (Telenomus spp.) with parasitism levels going over 90% in some instances.