Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2002
Publication Date: 10/1/2002
Citation: OPPERT, B.S., HARTZER, K., ZUERCHER, M.C. DIGESTIVE PROTEINASES IN LASIODERMA SERRICORNE (FABRICIUS) (COLEOPTERA: ANOBIIDAE). BULLETIN OF ENTOMOLOGICAL RESEARCH 92: 331-336. 2002. Interpretive Summary: The cigarette beetle is a common pest of many types of grains and stored products. The primary fumigant used to control the beetle is phosphine, but phosphine-resistant beetles have been reported. We want to identify proteins that may be used in transgenic grains to provide enhanced protection from cigarette beetle damage. We evaluated the types of enzymes used by cigarette beetle larvae to digest food. These enzymes were classified as serine proteinases, and they were extremely sensitive to serine proteinase inhibitors from soybean. The data suggest that soybean inhibitor genes may be incorporated into the genomes of grains to improve integrated pest management of cigarette beetles.
Technical Abstract: We report a study on digestive proteinases of the cigarette beetle, Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae), a common pest of stored foods. Although the luminal contents of L. serricorne were slightly acidic, optimal casein hydrolysis by luminal proteinases was in pH 8.5-9.0 buffers. The major digestive proteinases are from the serine subclass, as evidenced by substrate and inhibitor analysis. The most effective inhibitors of caseinolytic hydrolysis were from soybean (both Bowman-Birk and Kunitz), with some inhibition by chymostatin, n-tosyl-l-phenylalanine chloromethyl ketone, and leupeptin. Casein zymogram analysis identified at least eight proteolytic activities. Activity blot analysis indicated one major and one minor n-a-benzoyl-l-arginine p-nitroanilide-hydrolyzing proteinase, and four major and two minor n-succinyl ala-ala-pro-phe p- nitroanilide-hydrolyzing proteinases. The lack of activation by thiol reagents, alkaline pH optima, and the results from class-specific proteinase inhibitors suggested the absence of cysteine, aspartic, and metallo proteinases. The data suggest that protein digestion in L. serricorne is primarily dependent on trypsin- and chymotrypsin-like proteinases.