Effect of protein extracts of Amaranthus retroflexus (Amaranthaceae) and Cuminum cyminum (Apiaceae) on digestive proteinases and biological characters of Helicoverpa (Heliothis) armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract

AbstractPlant proteinase inhibitors are among the promising biopesticides which are induced in plants tissues against the several Lepidoptera pests to inhibit digestive proteases. In this study, protein extracts of two nonhost plant seeds, Amaranthus retroflexus Linnaeus (Amaranthaceae) and Cuminum cyminum Linnaeus (Apiaceae), were examined on Helicoverpaarmigera (Hübner) (Lepidoptera: Noctuidae). The results obtained by using azocasein as a substrate showed that inhibitory activity of general proteases of the larvae fed on a diet incorporated with both inhibitors was dose dependent. Seed extracts of A. retroflexus and C. cyminum at the highest concentration showed that inhibition activities of chymotrypsin-like proteinase and trypsin-like proteinase were between 31–45% and 28–61%, respectively. Based on polyacrylamide gel electrophoresis, all of the proteinase isoforms, including those of A. retroflexus seed extracts, disappeared entirely, and only one band was detected in the seed extracts of C. cyminum. Larval mortality in the larvae fed on A. retroflexus and C. cyminum seed extracts was 56 ± 2.15 and 68 ± 2.23, respectively, but mortality in control (no seed protein extract) was 12 ± 2.34 individuals. Also, the life table parameters were affected significantly by A. retroflexus and C. cyminum protein seed extracts. Therefore, A. retroflexus and C. cyminum seed protein extracts showed inhibitory effect on H. armigera digestive proteinases and adverse effects on survival and fitness of the pest; hence, they could be introduced as a successful biopesticide in the near future.