Inhibitory activity of proteinaceous inhibitors from Cassia angustifolia and Trigonella foenum-graecum seeds against Plodia interpunctella (Lepidoptera: Pyralidae): interaction of the inhibitors and the insect digestive enzymes

Abstract

The cosmopolitan Indian meal moth, Plodia interpunctella Hübner (Lep.: Pyralidae), is a serious pest that causes economic damages to many strategic stored products. Plant protease inhibitors (PIs) have been shown to play essential roles in regulating proteolytic processes in insects. Plant PIs have been recently considered as a potential safe weapon against insect pests either through their direct assay or by expression in transgenic plants. Proteinaceous extracts were obtained from the seeds of two medicinal legumes plants namely, Senna (Cassia angustifolia) and Fenugreek (Trigonella foenum-graecum). Larval digestive trypsin of P. interpunctella was inhibited in treatments with these inhibitors up to 99.79 ± 7.5 and 61.29 ± 2.2%, respectively, by using Nα-benzoyl-DL-arginine-p-nitroanilide substrate. Total proteolytic inhibitory activity of P. interpunctella larval midgut was studied in both absence (control line) and presence of the extracts taken from Senna and Fenugreek seeds. Several thick bands (a–d) were detected very close to each other’s in control line. The width of detected bands was reduced in samples treated by both inhibitors.

Keywords:

• Plodia interpunctella
• trypsin-like enzyme
• plant proteinaceous inhibitor
• Zymogram

Acknowledgements

We thank MSc and PhD students, Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran, for sharing their experiences.