Nictating behavior and infectivity of entomogenous nematodes, Steinernema spp., to the larvae of common cutworm, Spodoptera litura (Lepidoptera: Noctuidae), on the soil surface

Behavior and infectivity of Steinernema feltiae (DD-136), S. bibionis, and S. glaseri to the last instar larvae of common cutworm, Spodoptera litura, on the soil surface were investigated under laboratory conditions. Upward movement of S. feltiae was enhanced by placing an insect on the soil surface, while the movement of other steinernematids was less enhanced. On the soil surface, S. feltiae actively nictated taking a waving and straight postures; S. bibionis less frequently nictated for a shorter time without taking a straight form; S. glaseri usually crawled on the surface and rarely nictated except when it traveled to neighboring soil particles. In the presence of a S. litura larva, S. bibionis and S. glaseri were more attacted by the feces than by the insect itself, though S. feltiae was strongly attracted by the insect. Feeding and defecating activities of the insect significantly declined with the inoculation with S. feltiae but not with S. bibionis or S. glaseri.