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Partial characterization of the proteolytic enzymes in the gut of the banana weevil, Cosmopolites sordidus , and effects of soybean Kunitz trypsin inhibitor on larval performance
Author(s) -
Montesdeoca M.,
Lobo M. G.,
Casañas N.,
Carnero A.,
Castañera P.,
Ortego F.
Publication year - 2005
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1111/j.1570-7458.2005.00329.x
Subject(s) - biology , aminopeptidase , chymotrypsin , cathepsin b , trypsin , exopeptidase , carboxypeptidase , cathepsin , proteolytic enzymes , biochemistry , trypsin inhibitor , weevil , leucine , proteolysis , leupeptin , botany , endopeptidase , kunitz sti protease inhibitor , enzyme , amino acid , protease
The proteolytic enzymes in the gut of the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), have been characterized. Both larvae and adults rely on a complex proteolytic system based on at least cathepsin D‐, cathepsin B‐, trypsin‐, chymotrypsin‐, leucine aminopeptidase‐, carboxypeptidase A‐, and carboxypeptidase B‐like activities. All endoproteolytic activities were higher in the anterior section of the gut, whereas the exopeptidases were evenly distributed in the anterior and middle sections, and almost no activity was detected in the posterior section. Gelatin‐containing gels confirmed the spatial organization of the proteolytic digestive process. According to this proteolytic profile, the STI (soybean Kunitz trypsin inhibitor) was tested in vivo to establish its potential as a resistance factor against C. sordidus . Newly hatched larvae fed on diets containing 0.2% (w/w) STI experience lower survival rates and display significant reductions in larval growth. Biochemical analysis carried out on guts of larvae reared on STI‐treated diet showed a reduction of trypsin‐like activity compared to that from larvae fed on control diet. This decrease was compensated with an induction of cathepsin B, whereas cathepsin D, chymotrypsin, and leucine aminopeptidase were not affected. These results are discussed as a basis for selecting appropriate inhibitors to obtain transgenic banana and plantain plants with enhanced resistance to this pest.