Selection of Entomopathogenic Nematodes against Dalaca pallens (Lepidoptera: Hepialidae)

Abstract

Dalaca pallens (Blanchard) is a pest with great impact on grassland production in Chile. The objective of this research was to evaluate the use of entomopathogenic nematodes (EPN) against D. pallens larvae. Twenty EPN isolates, collected along Chile, were used for nematode selection. The experimental unit consisted of five 50-mL plastic vials filled with Nothofagus dombeyi sawdust and inoculated with 40 dauers per vial. The experimental design was a completely randomized with four replicates per treatment. The results showed that isolate QU N3 (Steinernema australe) and QU N13 (Steinernema unicornum) produced the highest mortality, with 100 and 95% respectively and no differences (P < 0.001) between both. Later, these two isolates were used to calculate the lethal concentration (LC50 and LC90). Concentrations of 0, 10, 20, 30, 40, and 50 dauers per 50-mL plastic vials filled with Nothofagus sawdust were evaluated. Then, a single larva of D. pallens was added to each vial and incubated for 13 d. The results showed that LC50 and LC90 were equivalent to 14 and 39 dauers mL -1 for isolate QU N3, while for isolate QUN13 these figures were 14 and 48 dauers mL -1 . Consequently, there are native isolates of EPN with the ability to control D. pallens larvae, which require future test under field conditions.