Amblyseius orientalis (Ehara) (Acari: Phytoseiidae) is an effective predatory mite for spider mites control on fruit trees in China. In recent decade, it can be produced commercially and intensively via Carpoglyphus lactis (Linnaeus) in natural enemy factory. During the practical predator production, ratio of predatory mites to their prey was found critical for the population increase of A. orientalis in large-scale rearing. In this study, we investigated the predatory capacity of A. orientalis on different developmental stages of the prey C. lactis and the effect of prey numbers on predator reproductions. The maximum predation number of A. orientalis adults on C. lactis adults was 2.21 at the lowest density of 5 and on C. lactis eggs was 45.07 at the highest density of 60. The preference index Ci of A. orientalis on C. lactis eggs and adults was 0.4312 and − 0.9249, respectively, suggesting that A. orientalis preferred eggs to adults of C. lactis. A. orientalis could reproduce when it preyed either eggs or deutonymphs of C. lactis. However, the fecundity of the predatory mites is not proportional to the provided prey density in a week. Higher density of prey deutonymphs resulted in lower fecundity, while more prey eggs can bring higher fecundity of A. orientalis. Therefore, our study indicated that suitable density and developmental stage of prey is the basis for A. orientalis production in a large scale.

The broad mite, Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae), is a cosmopolitan pest that infest many greenhouse crops. Biological control is an important way to control P. latus, with predatory mites being the most widely used natural enemy of this pest. The purpose of this study is to evaluate the capabilities of three native phytoseiids in China (Neoseiulus californicus, Neoseiulus barkeri and Amblyseius orientalis) in controlling P. latus, using Amblyseius swirskii, a commercial biological control agent of this pest widely used in Europe as a control. Consumption, development, and reproduction of the four species when fed with P. latus were assessed, and their life table parameters were estimated and compared. Among the three native species, A. orientalis has the highest consumption rate of P. latus (29.0 per day), the shortest developmental duration (5.32 d), and the highest cumulative fecundity (13.50 eggs/female). Overall, its intrinsic rate of natural increase (rm) is 0.12, comparable to that of A. swirskii. Among the three candidates, A. orientalis is the only one that population increase might be expected when fed with P. latus. Therefore, we suggest it to be a potential biological control agent for this pest in China.