title: Activities of Digestive Enzymes in the Omnivorous Pest Apolygus lucorum (Hemiptera: Miridae).
abstract: The mirid bug Apolygus lucorum Meyer-Dür, 1843, an omnivorous species that feeds on plants and animals, has become a major pest in China as production of Bt-cotton has grown to such a large scale. Its omnivory is likely to be critical for its success, but the digestive mechanism(s) underlying processing and adsorption of such diverse foods is relatively unknown. Here, we examined the activities of digestive enzymes of A. lucorum in the salivary gland complex and midgut and the effect of sex, age, and food source on these activities. Amylase and protease were present in the salivary gland complex and the midgut, but were higher in the salivary gland complex. Trypsin-like enzyme was also present in both organs, but chymotrypsin-like enzyme was present only in the midgut. Sex, age, and food source affected the activities of these digestive enzymes. In general, the activities of these enzymes peaked at 10 d after emergence, and amylase and protease activities were higher in female adults than in males. Of the food sources tested, green bean pods (Gb) induced the highest amylase activity, whereas Helicoverpa armigera Hübner, 1809 eggs (He) and a mixture of Gb and He induced higher activities of the trypsin-like and chymotrypsin-like enzymes. The results from food switching experiments confirmed that amylase activity could be induced by plant sources, and animal sources induced protease activity. Thus, the types and activities of digestive enzymes in A. lucorum provide the physiological basis of the pest's omnivory.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Li
authors.affiliation: College of Plant Protection, Henan Agricultural University, Zhengzhou, China.
authors.forename: Xincheng
authors.initials: X
authors.lastname: Zhao
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yuan
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Kongming
authors.initials: K
authors.lastname: Wu
mesh_terms: D000818:Animals; D005247:Feeding Behavior; D005260:Female; D020062:Heteroptera / Q000254:growth & development / Q000502:physiology*; D019476:Insect Proteins / Q000378:metabolism*; D008297:Male; D009758:Nymph / Q000254:growth & development / Q000502:physiology; D010447:Peptide Hydrolases / Q000378:metabolism*; D012469:Salivary Glands / Q000737:chemistry
chemical_list: D019476:Insect Proteins; C011545:semen liquefaction factor; D010447:Peptide Hydrolases
keywords: Apolygus lucorum; diet; digestive enzyme; midgut; salivary gland complex