Culture Method and Efficacy of Entomopathogenic Nematodes (Rhabditida: Steinernematidae and Heterorhabditidae)

The effect of culture method on the efficacy of entomopathogenic nematodes was assessed by analysis of 511 greenhouse and field trials. In tests against larvae of the Japanese beetle, Popillia japonica Newman, and black vine weevil, Otiorhynchus sulcatus (F.), infective juveniles of Steinernema carpocapsae (Weiser) reared by in vivo, in vitro solid, and in vitro liquid culture methods provided equivalent larval reductions. Heterorhabditis bacteriophora Poinar infective juveniles produced in vivo and on solid media provided equivalent results in trials against Japanese beetle larvae and northern masked chafer, Cyclocephala borealis (Arrow). By contrast, H. bacteriophora produced by liquid culture achieved significantly lower Japanese beetle reductions than those reared in vivo or on solid media. Against the northern masked chafer, liquid culture H. bacteriophora provided significantly less host mortality than solid culture nematodes. Field persistence studies provided further evidence that liquid culture H. bacteriophora were inferior to infective juveniles produced on solid media. The poor performance of liquid culture H. bacteriophora was attributed to low lipid assimilation. (C) 1991 Academic Press, Inc.