Infectivity of an isolate of Steinernema sp. (Steinernematidae) in larvae of Pseudoplusia includens (Lepidoptera: Noctuidae) and Tenebrio molitor (Coleoptera: Tenebrionidae).

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

Cancún

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

Pseudoplusia includens is an important defoliating species of several cultivated plants, such as cotton, tobacco, and alfalfa, whereas Tenebrio molitor is a stored-grain pest. Susceptibility of larvae of those insects was evaluated under laboratory conditions by applying an isolate of Steinernema sp. recently detected in soil from the locality of La Bolsa (Santa María department, Córdoba province, Argentina). Two doses of infective juveniles (IJ) were used: 50 and 100. Infections (n=15) were performed individually in Petri dishes (35 mm diameter) and kept at 25°C. Mortality (expressed as percentage) was checked every 24 h during 9 days post-inoculation (DPI). Once the insect was dead it was placed in a White trap to ensure IJ emergence. Larvae died after different periods, depending on the inoculum dose: a) P. includens: 2 to 6 DPI (at a dose of 50 IJ) and 1 to 8 DPI (100 IJ); b) T. molitor: 2 to 5 DPI (50 IJ) and 2 to 6 DPI (100 IJ). Mortality was 100% for P. includens (both doses) and 40% (50 IJ) and 60% (100 IJ) for T. molitor. Mortality percentage showed significant differences between species but not between doses for a single species. In all the treatments, the nematode completed its life cycle and produced new IJ. The insects, especially P. includens, showed susceptibility to the isolate evaluated.