An insect bioassay to evaluate feed barley of different lysine content

Newly hatched larvae of the confused flour beetle, Tribolium confusum Duval were reared individually until pupation on ball-milled samples of five lines and two cultivars of feed barley of known lysine content. The period of larval development ranged from almost 20 to 23.7 days. It was significantly shorter (P < 0.01) on the three lines containing the highest amounts of lysine (4.42–4.55 g lysine 100 g-1 protein) than on the two lines and two cultivars with the lowest levels of lysine (3.38–3.86 g lysine 100 g-1 protein). There was a high correlation between the mean duration of larval development and lysine content (r = ?0.81 and ?0.94 for lysine 100 g-1 protein and lysine 100 g-1 sample, respectively). It is concluded that the flour beetle bioassay is a reliable and relatively rapid and economical method for screening lines in a barley breeding programme and for evaluating protein quality on the basis of lysine content.