author(s)
Oriolowo OB, Ande AT, and Azeez MO

abstract
Respiratory activity is an important indicator of life processes and physiological status of all organisms. This is because it reveals how energy is acquired, transformed, allocated, utilized or stored in organisms. Estimating metabolic rate in insects therefore provides a viable approach to determining several physiological landmarks such as diapause development. This study investigated the phenomena of diapause in the larval and pupal developmental stages of Cirina forda through a measure of its developmental metabolic rates. A total of 36 larvae and 80 pupae were used for the experiment. The insects were reared and maintained under ambient temperature and relative humidity (25-32 ^oC; 75-85% RH) in the laboratory. Metabolic rate was progressively measured as individual’s rate of O₂ consumption and CO₂ evolution using spirometric and titrimetric methods respectively over the six larva instar stages and the ten months of pupa developments. Data obtained were compared using Analysis of Variance (ANOVA) and means were separated using Fisher’s Least Significant Difference (LSD). The result showed that there was significant suppression of about 87% in O₂ consumption (F₁, 14=33.34; ANOVA, p<0.05) and about 86% suppression in CO2 evolution (F₁, 14=9.22; ANOVA, p<0.05) during pupa development. However, the respiratory quotient (RQ) of larva and pupa were not significantly different (F₁, 14=4.15; ANOVA, p>0.05). The study revealed that C. forda experienced an extremely low metabolism during pupa development which suggested diapause development in the insect and this period of highest metabolic suppression occurred in pupae of age between 90-150 days.