HEAT OF RESPIRATION OF CRYPTOLESTES-FERRUGINEUS (STEPHENS) ADULTS ANDLARVAE IN STORED WHEAT

The heats of respiration of Cryptolestes ferrugineus (Stephens) (Coleo ptera:Cucujidae) adults and larvae were measured both directly and ind irectly by CO2 production in an adiabatic respiratory calorimeter. The heat production of 4-week old adults (2500 insects/200 g of wheat) an d the second, third, and fourth instar larvae (1250 larvae/200 g of wh eat) was determined at five initial grain temperatures (15, 20, 25, 30 , and 35 degrees C) and three moisture contents (12, 15, and 18% wet m ass basis). Each variable and its interactions significantly affected heat production (p<0.001). Heat production by the adults increased exp onentially with increasing temperature from 15 to 35 degrees C. Althou gh heat production increased with increasing moisture content, the rat e of increase from 12 to 15% m.c. was greater than from 15 to 18% m.c. Heat production also increased with increasing wheat breakage and the increase from sound to 10% broken wheat was greater than from 10 to 2 0% broken wheat. Heat production rates ranged from 0.72 mu W/insect at 15 degrees C in sound wheat of 12% m.c. to 21.47 mu W/insect at 35 de grees C in 20% broken wheat of 18% m.c. Heat production of the larvae increased linearly with increasing level of each variable. Heat produc tion rates of the larvae ranged from 0.37 mu W/larva for the second in star at 20 degrees C and 12% m.c., to 17.53 mu W/larva for the fourth instar at 35 degrees C and 18% m.c. Interaction between temperature an d moisture content on heat production was modelled by exponential and linear regression equations.