Heat production by adult Cryptolestes ferrugineus (Stephens) of different ages and densities

The heat of respiration of adult Cryptolestes ferrugineus at three ages (one, four, and eight weeks old) at 2500 insects/200 g of wheat and three population densities (1250, 2500, and 5000 insects/200 g of wheat) with four-week old insects was measured in a computercontrolled, adiabatic respiratory calorimeter at three initial grain temperatures (15, 25, and 35 °C) and three moisture contents (MCs) [12, 15, and 18% wet basis (WB)]. Age, density, temperature, and MC significantly affected heat production ( P < 0.001). Heat production rates increased with both increasing initial grain temperature and moisture content. Heat production by age was highest in four-week old adults (9.41 μ W/insect), whereas that of eight-week old adults (7.81 μ W/insect) was slightly higher than for adults one week old (7.40 μ W/insect). Heat production per insect by density was highest at 2500 insects/200 g of wheat (9.41 μW/insect) and lowest at 5000 insects/200 g of wheat (6.38 μ W/insect). Instantaneous rates of heat production measured over the test period were affected by the combination of age, density, moisture content, and temperature increase.