Bioenergetics of Cynaeus angustus (Coleoptera: Tenebrionidae) Feeding on Stored Corn

Abstract

An energy budget was determined for Cynaeus angustus (LeConte) reared singly on split corn kernels at 30 ± 1°C and 80 ± 5% RH, the efficiencies of energy use calculated, and comparisons of bioenergetic data made with eight other stored-product insects. Average energy in joules (J) accumulated in biomass per individual in the developmental stages was as follows: egg, 1; first instar (L1), <1; L2, <1; L3, 1; L4, 2; L5, 5; L6, 3; L7, 18; L8, 20; L9, 39 J. The mean energy content of one corn kernel was 4,076 J. A mean of 30.99 mg of corn (598 J) was ingested during development and ca. 444 mg of corn (8,569 J) could be ingested during a 100-d adult period. During development, 206 J were lost as feces. The highest rate of O2 consumption (88 µl O2.mg−1.h−1) occurred in L2 on day 10, but most oxygen was consumed by L9 on day 46 (25 µl O2 per individual per h). During the 64-d developmental period, 247 J were lost through respiration and 88 J were used for growth. Mean assimilation efficiency was 55.5% for larvae and 66.0% for adults; mean gross production efficiency was 14.7% for larvae and 4.9% for adults; mean net production efficiency was 26.5% for larvae and 7.5% for adults. In comparison with other storage insects with known energy budgets, C. angustus was the largest beetle; larval consumption was greater than that of other beetles but similar to that of the moths, Plodia interpunctella (Hubner) and Ephestia cautella (Walker); total adult consumption was greater than that in the other storage insects; efficiencies of energy use by immatures were near those of Tribolium castaneum (Herbst), Cryptolestes ferrugineus (Stephens), and P. interpunctella .