Identification and biochemical characterisation of α-amylase in the alimentary tract of Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

Abstract

Mediterranean fruit fly (Medfly), Ceratitis capitata, is an important pest of many fruit crops in temperate and subtropical regions worldwide. α-Amylases are hydrolytic enzymes involved in carbohydrate metabolism in insects. There is no report about α-amylase activity in C. capitata in literature. So, the aim of the current study was biochemical characterisation of α-amylase in the alimentary canal of the pest to gain a better understanding of digestive physiology of the insect. α-Amylase of Medfly was extracted and characterised using starch as the substrate. The results showed the presence of α-amylase activity in the gut of the insect for carbohydrate digestion. Optimum activity of the enzyme occurs at pH 8.0 and 40 °C. The most effective activator of the enzyme was determined in treatment with 20 mM CaCl₂. Na⁺, K⁺ and Mg²⁺ ions also activated the enzyme. Native PAGE of α-amylase showed two isoenzymes suggesting the importance of α-amylase in the carbohydrate digestion in the insect. Understanding of the digestive physiology and α-amylase activity of Medfly is important when new management strategies for this economically important pest are devised.

Keywords:

• alimentary tract
• digestion
• α-amylase
• Ceratitis capitata
• isoenzyme

Acknowledgements

The first author is so grateful to Miki Ben Yosef for determining anatomical parts of the gut in Medfly and Dr. Edouard Jurkevitch for his useful guides. Also we thank Iman Sharifian for his assistance.