Overproduction of Digestive Enzymes Compensates for Inhibitory Effects of Protease and α-Amylase Inhibitors Fed to Three Species of Leafrollers (Lepidoptera: Tortricidae)

Autor: William A. Laing, J. Z. Mchenry, Ngaire P. Markwick, M. R. Newton, John T. Christeller
Rok vydání: 1998
Předmět:
Zdroj: Journal of Economic Entomology. 91:1265-1276
ISSN: 1938-291X
0022-0493
DOI: 10.1093/jee/91.6.1265
Popis: The larvae of 3 leafroller species -Epiphyas postvittana (Walker), Planotorlrix octo (Dugdale), and Ctenopseustis obliquana (Walker)-were chronically fed 6 digestive enzyme inhibitors in artificial diets over a 2-wk period, and their growth rate and digestive enzyme activities were measured. The inhibitors were fed singly and in selected combinations. Three protease inhibitors were extracted from potatoes (proteinase inhibitorsl and 2-POTI and 2-and carboxypeptidase inhibitor-CPI) and the 4th was bovine pancreatic trypsin inhibitor (BPTI). The 2 a-amylase inhibitors were extracted from wheat, the dimer and tetrarner. POTI and BPTI alone significantly reduced the growth rate of E. postvittana and P. octo . Most combinations of inhibitors did not reduce growth rate further than the single most effective constituent. However, ingestion of any of the inhibitors affected digestive enzyme activity. a-Amylase inhibitors increased a-amylase activity (up to IO-fold). BPTI, either singly or in combination, reduced measurable trypsin activity (1O-fold) and raised chymotrypsin activity (up to 3-fold) in all species. In larvae chronically fed POTI or BPTI, in vitro tests showed that the sensitivity of caseinase and chymotrypsin to protease inhibitors was unchanged. However, a very small amount of insensitive trypsin was produced. Because larval growth rate was so rarely significantly affected when inhibitors were added to the diet, whereas major enzyme activities were significantly altered, the question of compensation of one digestive enzyme for another is discussed.
Databáze: OpenAIRE
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