Effect of Steinernema feltiae on Spodoptera frugiperda and Heliothis zea (Lepidoptera: Noctuidae) in Corn

The entomogenous nematode Steinemema feltiae Filipjev was evaluated for control of fall armyworm, Spodoptera frugiperda (J. E. Smith), in vegetative field corn (Zea mays [L.J] and for control of fall armyworm and corn earworm, Heliothis zea (Boddie), in sweet corn ears. In 3 yr of field tests in vegetative field corn, spraying the nematode resulted in up to 33-43% infection of fall S. frugiperda larvae and occasionally significant (P <0.05) reductions in numbers of S. frugiperda infesting the corn. There was no significant increase in total yield of corn, although the dry weight of kernels per ear was significantly (P < 0.05) greater in treatment plots than in control plots. Nematode dosage had a significant effect on percentages of infection, but neither spray volume nor the addition of a surfactant affected insect control by the nematode. In one experiment in sweet corn, spraying the nematode onto corn ears resulted in up to 71% infection and up to 53% reduction of a mixed population of H. zea and S. frugiperda, mostly the former. Nematode treatments did not increase sweet corn yield by weight. However, spraying the nematode at a pressure of 0.70 kg/em2 resulted in a significantly (P < 0.05) higher percentage of US #1 grade marketable ears than in control plots, whereas spraying at 1.76 kg/em2 did not, regardless of the nematode dose.