The effects of inoculum size on yield of Steinernema carpocapsae and Heterorhabditis bacteriophora in liquid culture

The inoculum size for maximum yield of S. carpocapsae Agriotos (A24) and H. bacteriophora (H06) was established. Using 500 ml flasks containing 100 g liquid medium, a maximum yield of 32 x 10(6) A24 was obtained with 8 x 10(5) juveniles in 16 days and of 30 x 10(6) H06 with 56 x 10(5) juveniles in 12 days. Generally, yield per infective increased with time and decreased with inoculum level. Total yield per unit time increased with inoculum size. H. bacteriophora cultures contained 90% or more infectives after at most 20 days. The importance of optimising the inoculum size and culture time is discussed.