Searching capacity of the entomopathogenic nematode Steinernema sp. SNIO 198 (Rhabditida: Steinernematidae)

The mobility and speed of entomopathogenic nematodes (Steinernema sp. SNIO198) were evaluated in soils of an oil palm plantation in Tumaco, Colombia in order to establish whether this control system could be applied for the management of Sagalassa valida, one of the most important pests that affects plantations. Plastic columns, 25 cm long, were used with two soil textures and four humidity levels. Five hundred nematodes were placed on top of each soil column, and in the lower part (24 cm) S. valida larvae were placed both inside primary palm roots and completely exposed. The number of Steinernema sp. infective juveniles (IJ) was evaluated at three depths at 24, 48, 72 and 96 hours after nematode application. The results showed that if the S. valida larvae are completely exposed, the majority of IJ were recovered between 48 and 72 hours. If the larvae are located inside palm roots, the majority of IJ were collected after 24 and 48 hours. Also, the movement of IJ in the two soil textures was gradual. The first IJ that could reach the host penetrated it; others stayed near the larvae or especially in the roots or in any of the three depths evaluated. The main conclusion is that Steinernema sp. SNIO198 exhibits cruising and ambush behavior.