Metabolic Reserves in Periplaneta Americana (Dictyoptera: Blattida)
  Key Words  
  Nutrient reserves, over-wintering, lipids, proteins, carbohydrates
  Nonggang Bao and William H Robinson
  Dietary carbohydrates, lipids, and proteins constitute the nutrient reserves for the American cockroach, Periplaneta americana. Adults collected from an urban population were evaluated by their body weight and for their storage and utilization of metabolic reserves. Mean dry body weight of females collected in December was significantly (P<0.05) higher than that of females in February, May, June, July, September, and October. Mean dry body weight of males collected in December was significantly (P<0.05) higher than that of February and August males. Mean content of total lipids in November females was 419.9 + 38.7 mg/g dry weight, and for February females was 197.1 + 42.8 mg/g dry weight. Glycogen contents in females and males significantly (P<0.05) increased in January and February. Highest glycogen was in February females at 217.9 + 29.9 mg/g dry weight, and lowest was in August females at 86.1 + 32.1 mg/g dry weight. Mean glycogen content in November females was 109.0 + 31.4 mg/g dry weight, and the highest was in February males at 235.8 + 31.1 mg/g dry weight. The lowest glycogen content was in November males at 81.0 + 33.2 mg/g dry weight. Mean content of total protein in November females was 498.8 + 31.2 mg/g dry weigh, and for February females it was 399.7 + 33.6 mg/g dry weight. Mean total protein in November males was 483.7 + 28.4 mg/g dry weight, and for February males it was 392.7 + 38.8 mg/g dry weight. Reduced winter foraging corresponds to little or no food intake, and utilization of metabolic reserves results in a significant decrease in lipid and protein storage. Glycogen in over-wintering P. americana is used in cold hardening. Carbohydrates serve both a nutritional and a cold hardiness function in overwintering.