INTERACTION BETWEEN 2 ENTOMOPATHOGENIC NEMATODE SPECIES IN THE SAME HOST

When Steinernema carpocapsae and Heterorhabditis bacteriophora (= heliothidis) simultaneously competed for the same insect species in Petri dishes, S. carpocapsae infected significantly more Galleria hosts than H. bacteriophora. When S. carpocapsae was added first followed by H. bacteriophora up to 15 hr, S. carpocapsae was the dominant species. When H. bacteriophora was added first, followed by S. carpocapsae at 0, 10, and 15 hr, S. carpocapsae infected 68% of the insect hosts at 0 hr and 67% at 10 hr, whereas H. bacteriophora infected 71% of the insects at 15 hr. Total percentage mortality by both nematode species in combination was higher than mortality for either species alone. A Steinernema species and H. bacteriophora cannot coexist when both species are inoculated directly into the hemocoel of an insect host. S. carpocapsae, S. feltiae (= bibionis) or S. glaseri, inoculated before H. bacteriophora at 3-hr intervals, was the dominant species. When a steinernematid species was inoculated in the same host after H. bacteriophora, steinernematid dominated for the first 6 hr. Thereafter, H. bacteriophora was the dominant species. © 1991.