Digestive physiology and food utilization of the larvae ofEarias vittella (Lepidoptera: Noctuidae) from its malvaceous host plant
The hydrogen-ion concentration of the contents of fore-, mid- and hindgut of the larva ofEarias vittella (F.) lays within a pH range of 8-8 and 9-6 These caterpillars possessed the ability to break down starch, raffmose, maltose, melibiose, sucrose and proteins. Synthesis of certain higher oligosaccharides indicating transglycosidic activity was also noticed during hydrolysis of raffinose, melibiose and sucrose inin vitro experiments. The activity of carbohydrases detected in the larval midgut was variably influenced by the hydrogen-ion concentration of the medium. Further, they differed from one another in their relative strength. Amylase was the most powerful and a-galactosidase was the weakest of all. An in vivo examination into the fate of fed starch, maltose, cellobiose and lactose within the gut revealed the physiological competency of the caterpillar to utilise only the first two carbohydrates (the former partly and the latter completely) through swiftly operating processes of digestion and absorption.
Movement of ingested food through the gut of the caterpillar was a rapid process. The first lot of food residue passed out of the hindgut within a mean time of 103 min after feeding. However, the entire alimentary canal got cleared of the ingested food only 36 h after a meal.