Effect of entomopathogenic nematode, Steinernema feltiae on survival and plasma phenoloxidase activity of Helicoverpa armigera (Lepidoptera: Noctuidae) in laboratory conditions

عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران

Lethal effect of Steinernema feltiae was evaluated against prepupae of Helicoverpa armigera in soil. Plasma penoloxidase activity of prepupae of H. armigera was evaluated against S. feltiae, too. In brief, 20-25 infective juveniles of S. feltiae in 20 μl Ringer’s solution were injected into the hemolymph of prepupae of H. armigera in different time intervals. In order to evaluate the effect of the Ringer’s solution, it was also injected into the larvae in a separate experiment as positive control. A third group of non-injected insects was used as negative control. Hemolymph of the insects was collected in different time intervals (0 to 24 h post injection). Phenoloxidase activity of H. armigera hemolymph were determined spectrophotometrically, using L-Dopa as substrate. The LC20, LC50 and LC80 values were 4.5, 19 and 76 IJ per insect, respectively. PO activity in nematode-injected insects compared with control groups (P < 0.05). Nematode-injected insects showed the highest plasma PO activity 8 h post-injection.

cotton bollworm؛ immunity؛ LC50؛ phenoloxidase