THE USE OF A NON-NUTRITIVE DIET AND URIC ACID MEASUREMENTS TO DETERMINE FOOD RESERVES IN RHODNIUS PROLIXUS STÅHL (HEMIPTERA: REDUVIIDAE)

Fifth-instar nymphs of Rhodnius prolixus were fed on an artificial diet consisting of 6 g of dextran (mol. wt. 60,000–90,000) and 0.1 g ATP in sufficient 0.15 M NaCl to give 100 ml. This diet causes a dilution of the haemolymph which leads to a decrease in the uric acid concentration, from the unfed level of 12.2 mg/100 ml to 7.3 mg/100 ml on the first day, and 5.2 mg/100 ml on the second day after feeding. The total amount of uric acid in the haemolymph remains constant over this period but increases by almost 80% on the third day. In contrast, the concentration and the total amount of uric acid in unfed insects remain constant over all 3 days. The digestive activation observed in insects fed on rabbit blood also occurs in insects fed the artificial diet, although it is delayed for 1 or 2 days in the latter. It has been shown that the "gut residue" in R. prolixus has a nutritive value and that this residue is utilized by the insect during periods of starvation.