Digestive proteolytic and amylolytic activities of Helicoverpa armigera in response to feeding on different soybean cultivars

BACKGROUND: Digestive proteolytic and amylolytic activities of the larvae of Helicoverpa armigera (Hubner) fed either on artificial diet or on different soybean cultivars (356, M4, M7, M9, Clark, Sahar, JK, BP, Williams, L17, Zane, Gorgan3 and DPX) and response of the larvae to feeding on some soybean-based protease inhibitors were studied. RESULTS: The highest general and specific proteolytic activities were in artificial-diet-fed larvae. Although the highest general proteolytic activity was in the larvae fed on L17, M4 and Sahar cultivars, the lowest tryptic activity was on L17 and Sahar, which may be due to the presence of some serine protease inhibitors in these two cultivars, resulting in hyperproduction of chymotrypsin-and elastase-like enzymes in response to the inhibition of these enzymes. The highest amylolytic activity was on M4, and the lowest was on Williams and DPX. General proteolytic activity of SKTI-fed larvae was the highest compared with SBBI- and STI-fed larvae. CONCLUSION: The findings demonstrated that the cultivars L17 and Sahar were partially resistant to this pest, probably because of some secondary chemicals or proteinaceous protease inhibitors of these cultivars.(C) 2010 Society of Chemical Industry