The effects of daily fluctuating low-oxygen conditions on life table parameters of Tribolium castaneum (Coleoptera: Tenebrionidae) and their subsequent generations in controlled atmospheres.

Understanding pest insect survival and development under conditions of fluctuating low oxygen levels (less than 4.4%) is of practical significance in the control of nitrogen atmospheres for grain storage. Egg hatching, sixth instar survival, adult emergence rate, and adult survival rates of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) were determined following 8-d exposure periods of eggs, sixth-instar larvae, pupae, and adults to daily fluctuating oxygen concentrations within ranges of 1.9% to 4.4%, 1.9% to 3.9%, 1.9% to 3.5%, 1.9% to 3.2%, 1.9% to 2.7%, 1.9% to 2.5%, and 1.9% to 2.1%. Fecundity was assessed in F0 females that developed from sixth-instar larvae surviving the exposure. The stage-specific survival and development time of their F1 progeny were subsequently evaluated. Normal air (approximately 20.9% oxygen) served as the control. As the daily oxygen concentration fluctuation changed from 1.9% to 4.4% to 1.9% to 2.1%, egg hatching success, sixth instar survival, adult emergence percentage, and adult survival rate of the F0 generation decreased significantly; the fecundity of the F0 generation fell from 168 to 29, and the F1 developmental time from egg to adult emergence increased from 39.5 to 52.2 d. Under daily oxygen fluctuations of 1.9% to 2.1%, the hatching rates of eggs and the adult emergence rates fell to 24.67% and 38.94%, respectively, while the survival rate of the first to seventh F1 instars fell to 61.75% to 76.25%, significantly lower than the 92.22% to 100% observed under control conditions. These findings highlight that biological fitness parameters are crucial criteria for controlling storage pest insects by fluctuating low-oxygen conditions.