Abstract: [Objective] In this paper, the effects of different fatty acids in artificial diets on growth, development and fecundity of the predator Arma chinensis (Heteroptera:Pentatomidae) were studied to provide a basis for the development of artificial diets of natural enemy insects.[Method] Two insect-free artificial diets were used to raising A. chinensis for continuous 12 generations. The diet 1 contained palm oil (a saturated fatty acid) and the diet 2 contained flax oil (an unsaturated fatty acid). The developmental time, stage-specific survival rate, sex ratio (♀:♂), adult body mass, oviposition period, number of eggs, percent hatch as well as intrinsic rate of increase were measured by the generations of F1, F4, F8 and F12.[Result] The results showed that the effects of two types of artificial diets on developmental time and reproduction of A. chinensis varied with generations and developmental stages. The developmental time of 2^nd and 3^rd instar nymphs of A. chinensis was significantly different between the two artificial diets from F1 to F12. However, the developmental time of 4^th and 5^th instar nymphs of A. chinensis showed significant difference until to F4 (5^th instar) and F8 (4^th instar). The effects of the two diets on the developmental duration at each age stage of A. chinensis tended to be stable from F8. The developmental duration of 2^nd and 3^rd instar nymphs fed on diet 1 was shorter than that of those on diet 2, but the developmental time of 4^th and 5^th instar nymphs fed on diet 1 was longer than those on diet 2. Thus, diet 1 was more beneficial to the early development of nymphs, while diet 2 was better for the later development of nymphs. The egg, 1^st nymph, total development (only significant difference in F1) and life span were not significantly different between two types of artificial diets. Similar to the development, the effect of the diet on mortality of 2^nd instar to 5^th instar nymphs and emergency rate were not significant in F1. Until to F4, the mortality of 2^nd and 3^rd instar nymphs and emergency rate fed on diet 1 were lower than those on diet 2, while the mortality of 4^th and 5^th instar nymphs fed on diet 1 were higher than that on diet 2. There were no significant differences in mortality of 1^st instar nymphs and eggs hatchability in each generation between the two diets. The adult body mass of male and female, and female MRGR(mean relative growth rate) fed on diet 1 were significantly lower than those on diet 2 until to F8. The fertility of A. chinensis fed on diet 1 was significantly higher than that on diet 2 from F4 to F12. The intrinsic growth rate and population doubling time of A. chinensis fed on diet 1 were better than diet 2 from F1 to F8, however, the difference in intrinsic growth rate and population doubling time between the two diets decreased with the increase of generations. Diet2 was better than diet1 in F12. The other fecundity indexes of A. chinensis (except for sex ratio of F1) fed on diet 1 and diet 2 were not significantly different.[Conclusion] The artificial diet containing saturated fatty acids (diet 1) can significantly shorten the developmental time, reduce mortality of young nymphs, and increase the female fertility rate of Arma chinensis, but the unsaturated fatty acid in the artificial diet (diet 2) is more suitable for the growth and development of old nymphs, improving the adult rate and the population growth rate of A. chinensis. Therefore, those results suggest that we should prepare the artificial feed according to the specific growth stage of feeding insects by adding or reducing the key nutrients at different stages of insect development, to achieve the best effect during the continuous rearing of natural enemy insects in future research and reproduction.

Key words: Arma chinensis, fatty acid, artificial diets, development, reproduction