Host Range Assessment of Helicotylenchus pseudorobustus (Tylenchida: Hoplolaimidae) on Pasture Species

L. T. Davis, N. L. Bell, R. N. Watson, T. C. Rohan

Abstract


During searches for pathogens to be used as classical biocontrol agents for Miconia calvescens (velvet tree), a devastating plant invader of Hawaii and French Polynesia, damaging angular leaf spots were found repeatedly. The etiological agent of this disease was identified as the nematode Ditylenchus drepanocercus. This nematode has a distinctive falciform appendage at the apex of the tail on both sexes, which allows easy identification. The nematodes were found in the lacunar parenchyma. Infected tissues have abnormally large cells (7 to 13 times the normal size). The lamina at infected areas is chlorotic, slightly thicker, and becomes necrotic with time. The best method of inoculation for this nematode was spraying plants with a suspension containing individuals of various stages on previously wounded leaves. Incubation period was determined to be 20 days.

Keywords


helicotylenchus pseudorobustus; host range; pasture species; spiral nematode; free-living nematodes

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