Abstract: The nutrition effects of seven commercial yeast products on Carpoglyphus lactis and further on Neoseiulus californicus, a predator of C. lactis, were investigated under laboratory conditions. The population size of C. lactis increased greatly when the mites were reared on yeast with 23.86%, 40.29% and 45.37% protein contents. Their population reached the peak on the 28th, 21st and 24th day, and increased by 117.1, 167.5, and 115.4 times on the three yeast diets, respectively. Lower population increase (<10.0 times of initial density) were observed for C. lactis reared on yeast with 25.90% and 32.40% protein contents. Yeast with 1.46% and 1.72% protein contents failed to sustain C. lactis population. C. lactis population parameters were significantly correlated with the concentrations of 15 amino acids. However, the soluble protein concentration in C. lactis was not significantly correlated with protein concentrations in the yeast diets. The soluble protein concentrations in C. lactis reared on yeast products with 23.86%, 40.29% and 45.37% protein concentration were 67.00, 60.53, 78.25 mg/g, respectively. The intrinsic increase rates of N. californicus were high (0.15, 0.14) when the predators preyed on C. lactis that were provided with yeast diets with 23.86% and 45.37% protein contents, with the net reproductive rate higher (10.61) with 45.37% protein contents. Therefore, it is advantageous for population growth in both C. lactis and N. californicus when yeast with 45.37% protein concentration is used.

Key words: Neoseiulus (Amblyseius) californicus, Carpoglyphus lactis, population dynamics, life table parameters, protein concentrations, amino acids