Abstract: Adult population of the psocid, Liposcelis bostrychophila, was reared with the artificial diet and exposed to the controlled atmosphere (CA) containing 35% CO₂, 1% O₂ and 64% N₂ at 28℃ for 30 successive generations in order to select a strain resistant to the controlled atmosphere (CA-R). Based on LT₅₀ values, the resistance factor (RF) had increased 5.6-folds at 30th generation and it seemed to have the potential of further development. Removal of selection pressure revealed that the resistance of CA-R was unstable and RF decreased by 63.2% after 5 successive generations. The effect of CA resistance on ecological fitness in the psocid was evaluated under CA-free condition. The results showed that the CA-R strain had no unfavorableness in development but obvious disadvantage in reproduction with a fitness value of only 0.39 relative to that of the strain sensitive to CA in terms of net reproductive rate (R₀).

Key words: Liposcelis bostrychophila, controlled atmosphere, resistance, stability, ecological fitness