Study On Pest Mites And Their Natural Enemies In Xinjiang Jujube Orchards And Predation Function Response Of The Dominant Natural Enemies

Pest mites are a vital kind of pest which can cause great damage to crops and forestry plants. There aremany species of pest mites and their damage characteristics are basically identical. Along with thecontinuous spread of jujube planting area and the increasing popularization of intercropping patterns, pestmites have been particularly serious in Xinjiang jujube industry, whose prevention and treatment are quitedifficult. In order to clearfy the species of pest mites and their natural enimies in Xinjiang jujube orchardsand to offer comprehensive pest mites control, the following three aspects were carried out in this paper.(1) To clarify the species of pest mites and their natural enemies in Xinjiang jujube orchards,51sampling points were investigated in the main jujube production regions of Xinjiang, which include25counties and cities belonging to6prefectures, from June,2013to August2013. The results showed thatthere are3species of pest mites, Tetranychus truncatus Ehara, Tetranychus dunhuangensis Wang andTetranychus sp., in Xinjiang jujube orchards at present. And Tetranychus truncatus Ehara is the dominantspecies. In addition, their natural enemies mainly include4species, which are Stethorus punctillum Weise,Oenopia conglobata Linnaeus, Scolothrips takahashii Priesner and Chrysopa sinica Tjeder. But thedominant natural enemies are various under different cropping planting patterns.(2) The population dynamics of Tetranychus truncatus Ehara and its natural enemies were monitored inthe Aksu region of Xinjiang from May,2013to September,2013. We investigated and analyzed by fixedpoints and fixed plants in two different kinds of jujube-crop intercropping fields, where Tetranychustruncatus Ehara has been very serious these years. And the population numbers of Tetranychus truncatusEhara and natural enemies were counted every3-5days. The results showed that the population trend ofTetranychus truncatus Ehara was the same as that of its natural enemies in both kinds of jujube-cropintercropping fields. That is to say there would also be an increase number of natural enemies when thepopulation of Tetranychus truncatus Ehara was increasing, and vise versa. In addition, as Tetranychustruncatus Ehara reached a peak in early-middle August under the two kinds of intercropping modes, itsnatural enemies would also peak about a week later. These indicated the control effect of natural enemieson Tetranychus truncatus Ehara under natural conditions.(3) The predatory abilities of Scolothrips takahashii Priesner, Stethorus punctillum Weise and Chrysopasinica Tjeder, three major natural enemies of Tetranychus truncatus Ehara, were studied in differentdensities under the room temperature condition. It was observed that the fed number of adults per daywould increase with the increase of density of mite within certain density range. The results were simulatedwith mathematical model of Holling, and there were not obvious differences between the theoretical datesand the practical dates. The control role of the three natural enemies to the mite showed significant value injujube orchards mite biological prevention.