Parasitoids
       
  What are the larval/pupal parasitoids of stem borer pests?  
  Describe the method for determining larval or pupal parasitation and name and identify seven larval/pupal parasitoids of stem borer pests.  
     
Determining larval or pupal parasitation
   During the early stages of parasitism, you may be unable to distinguish between a parasitized stem borer larva or pupa and a normal one. Over time, the pupa may become darker in color as seen below:

Parasitized pupa Unparasitized pupa

To determine whether a larva or pupa is parasitized, rear the individual larva or pupa in a transparent, closed containers with rice stems.The parasitoid larva will soon emerge and pupate outside the host. Some parasitoids parasitize the host larva but emerge from the host pupa.
  
Seven important larval/pupal parasitoids of the stem borer
   Click through the pages of the following flipbook to learn more about seven important larval/pupal parasitoids of the stem borer.
  
   

 

Parasitism at IRRI

   The table shows that the parasitism of stem borer eggs for Scirpophaga incertulas (Walker) is high at IRRI. Other parasitism stages and the incidence of parasitism for Chilo suppressalis (Walker) are often rather low.

Average percent parasitism per crop by parasites of eggs, larvae, and pupae of the yellow rice borer, Tryporyza incertulas and the striped rice borer Chilo suppressalis.
 
Parasitism
Season T. incertulas C. suppressalis
Eggs Larvae Pupae Eggs Larvae Pupae
1974 wet season 62 8 0 12 1 1
1974 wet to 1975 dry season 50 11 30 11 7 0
1975 dry season 43 10 63 2 1 1

 
Next lesson
   In the next lesson, we will learn about the parasitoids of leaf and plant hoppers.