Starvation of the Tobacco Hornworm, Manduca sexta.1 1. Changes in Hemolymph Characteristics of 5th-Stage Larvae2

Effects of total starvation on hemolymph characteristics of newly molted 5th-stage larvae of Manduca sexta (L.) reared at 25° and 30°C were studied. Only small changes from initial values of total hemolymph solids (g/100 g), specific gravity total protein (g/100 ml), and total hemocyte count/mm3 (THC) occurred as a result of total starvation for 72 h. Glucose levels (µM/ ml) were reduced to very low levels within 6 h following food deprivation, and trehalose levels (µM/ml) also decreased rapidly. Relatively large increases occurred in the first 3 of the foregoing parameters in larvae which were fed. However, THC showed little change, and glucose and trehalose levels actually decreased but at a significantly lower rate than those of the starved larvae. Effects of temperature on starved larvae were usually minimal. However, values from the same time in fed larvae reared at the 2 temperatures were often significantly different. Growth rates were somewhat faster at 30°C, but final weights were not different from those of larvae reared at 25°C.