Occurrence Dynamics Of Spider Mites And Evaluation Of The Effect Releasing Predatory Mites In Wangdu Apple Orchards

Spider mites is the main pests in apple production areas of China. At present control measures of spider mites mainly relies on spraying chemicals. A large number of pesticide not only kill natural enemies but also lead to pests resistant to accelerate. In order to understand the occurring dynamic of spider mites in apple orchard, to explore conservation and utilization of natural enemies and guide the rational and suitable using chemical pesticides in apple fruit, spider mites species and occurring dynamic is investigated. Meanwhile we also release predatory mites to control Panonychus ulmi Koch in two apple orchards of Wangdu county, Baoding city. The main results as follows:1. Spider mites species and occurring dynamicsSpecies and occurring dynamics of spider mites were investigated at Qilipu apple orchard and Xu zhuang apple orchard in 2014. The dominant spider mites population in two apple orchard all were P. ulmi. A lot of P. ulmi eggs overwintered on the apple branches in winter. The hatching stage of overwintering eggs was in early April 2014(in apple pink stage). The first generation of egg stage was at the end of April or early May(1 week after fallen petal). Henceforward, overlapping generations were very serious. The most severe harm happened in a middle of May to July. The population number of P. ulmi declined sharply in August. Overwintering eggs were founded in early October at fields.2. Effect evaluation of releasing predatory mitesPredatory mites--Neoseiulus barkeri Hughes is released on May,13, 2014 in Xuzhuang apple orchard. The population dynamic of P. ulmi and predatory mites is investigated in every 7d before and after releasing predatory mites. Control effect of N. barkeri was obvious. The number of spider mites in release area was 2963.33. The number of spider mites in control area was 4075.49. The number of P. ulmi in releasing area was significantly less than no-releasing area. Releasing predatory mites not only reduced miticide aplications, and but also protect natural enemies. Fruit quality and ecological environments will be also improved is more safer.