GRAY, E M; BRADLEY, T J; Univ. of California, Irvine; Univ. of California, Irvine: Metabolic Rate in Female Mosquitoes: Age, Size, Activity and Feeding Effects

Using flow-through respirometry, we have measured the pattern of CO₂ release from adult female mosquitoes in the species Culex tarsalis. Individual rates of CO₂ release and dry mass were also measured at rest for virgin and mated females between 0 and 16 days. At rest, females released CO₂ in regular bursts. Standard metabolic rate (SMR, as measured by average CO₂ release) was not significantly different between mated and virgin females. SMR increased in proportion to dry mass with an exponent of 0.45. This correlation was maintained within each age group (exponents between 0.50-0.65) and strengthened with age. Dry mass increased with age until 12 days. The increase in dry mass until 8 days was associated with an accumulation of lipids. The increase between 8 and 12 days was due to glycogen storage and accompanied by water accumulation. Hourly metabolic rate and flight activity following a blood or sugar meal were measured over a six-day period in two groups of 15 females. Sugar-fed mosquitoes remained calm during the day and had nocturnal increases in metabolic rate and flight activity with crepuscular peaks. The pattern observed in the blood-fed group was substantially different. Firstly, blood-feeding elicited a specific dynamic action during 54 hours, where daily metabolic rate increased up to 3.5 times SMR and night-time activity was cancelled. On the third night, activity was very high and eggs were laid. Finally, after 72 hours, the blood-fed group resumed the same diurnal pattern as the sugar-fed group. Supported by NSF grant IBN0079501.