An Energy Budget of Sitophilus oryzae (Coleoptera: Curculionidae)1

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Abstract
An energy budget study was carried out on the rice weevil to quantify the damage caused during development on wheat. Maximum rate of oxygen consumption (438 µl/individual/day) occurred on the 15th day of the life cycle. The total energy lost through respiration in the developmental stages and adults up to 50 days was 28.25 cal. The average caloric contents per individual in the developmental stages were: egg, 0.038; 1st instar (L1), 0.09; L2, 0.27; L3, 0.82; L4, 3.57; prepupa, 5.86; pupa, 4.03; adult, 4.36. The average caloric content of a wheat kernel (Neepawa variety) was 126 cal. Studies on cumulative ingestion and egestion revealed that 46.78 cal/individual were ingested from a wheat kernel and 8.59 cal/individual egested in a 50-day period. Maximum food consumption (16.7 cal) was recorded in L4 stage. The cumulative production in 50 days was 9.83 cal/individual. Ecological growth efficiency was the lowest in the 1st instar (5.8%) and the highest in the prepupae (17.39%). Assimilation efficiency of all the developmental stages was high (avg. 79.8%).