Susceptibility of larvae of Spodoptera frugiperda and Helicoverpa gelotopoeon to the entomopathogenic nematode Steinernema diaprepesi under laboratory conditions.

CACCIA, M.G.; LAX, P.; DEL VALLE, E.; DOUCET, M.E

Cancún

Congreso; XLIV Reunión Anual de la Organización de Nematólogos de los Trópicos Americanos (ONTA); 2012

Spodoptera frugiperda and Helicoverpa gelotopoeon (Lepidoptera: Noctuidae) are polyphagous species that cause severe losses to different crops. Susceptibility of last-instar larvae of both insects to infective juveniles (IJ) of a Steinernema diaprepesi isolate from the locality of Santa Rosa de Calchines (province of Santa Fe, Argentina) was evaluated under laboratory conditions. The insects were individually placed in Petri dishes (35 mm diameter) and the following IJ doses were applied: 0 (control), 50, and 100 (n=15); dishes were maintained at 25°C. Mortality (expressed as percentage) was evaluated every 24 h for 6 days. Four days after the insect death, the cadaver was put on a White trap; emerging IJ were extracted during 10 days and further counted. At the end of the experiment, mortality of S. frugiperda was 93% (at a 50 IJ dose) and 100% (at a 100 IJ dose), whereas in H. gelotopoeon, mortality was 87% (50 IJ) and 93% (100 IJ). No mortality was registered in the untreated insects. IJ production was significantly different between doses for S. frugiperda (11329 at 50 IJ vs. 27150 at 100 IJ); however, it was not significant for H. gelotopoeon (19830 at 50 IJ vs. 26361 at 100 IJ). No differences were observed between species subjected to the same IJ dose. These results showed the susceptibility of both leptidopterans to the isolate of S. diaprepesi.