Investigation And Comparisons Of Predation Ability Of Two Predacious Acarids In Citrus Orchards In Chongqing

Predacious acarids are considered to be an important natural enemy resource in the citrus orchards ecosystem. Based on the local orchards survey of acarid diversity in different farming pattern in Chongqing. With the purpose of offering significative references for IPM (Integrated Pest Management) in citrus orchards, impacts of different farming patterns on population dynamics of acarids and their predators were investigated, predacious functions between indigenous and exotic species were also compared. Results are showed below:1. Species investigation of Predacious acarids in the citrus orchardsAfter investigating the main citrus orchards in Chongqing,3families and11species were identified, including Amblyseius pseudolongispinosus, Amblyseius tsugawai, Amblyseius herbicolus, Amblyseius eharai, Amblyseius okinawanus, Amblyseius makuwa, Euseius nicholsi and Euseius ovalis, which belong to Phytoseiidae. Agistemus exsertus and Agistemus terminalis belonging to Stigmaeidae were also found, added by Anystis baccarum belonging to Anystidae. It indicated that there were a large number of predacious acarids in Chongqing, which were available and beneficial.2. Impacts of different fanning patterns on population dynamics of acarids and its predatorsIn Qinglong citrus orchards in Wanzhou District in Chongiqng, From April to October,3plots with different fanning methods were chosen to survey the population dynamics of acarids. Results showed that the peak occurred from the beginning in May to the end of June, and its damage and lasting time varied based on different orchards. Population during the peak period was plot Ⅱ> plot Ⅰ> plot Ⅲ, plot Ⅱ lasted longest in all3plots. While predators population order was plot Ⅲ> plot Ⅰ> plot Ⅱ. This revealed that planting luffa and keeping some weeds would play a certain role in restraining mites spreading, and protecting predators as well.3. Predacious functions comparison of Euseius nicholsi and Amblyseius cucumeris to Panonychus citri McgregorIn the artificial climate chamber (Relative Humidity85±5%, photoperiod8L:16D), predation abilities of Euseius nicholsi and Amblyseius cucumeris to Panonychus citri Mcgregor under different temperature was conducted and compared. Result showed that this the predation belonged to Holling Ⅱ. At20-28℃, preying effectiveness (a/Th) of Amblyseius cucumeris was higher than that of Euseius nicholsi, while when it changed to32-35℃, Euseius nicholsi was better than that of Amblyseius cucumeris. Hanger-resistant test revealed that under certain harsh environment, Euseius nicholsi played better than Amblyseius cucumeris. Intraspecific intervention test told that mutual competition and interference do exist between individuals of the two mites.