不同猎物及密度对巴氏新小绥螨和拉戈钝绥螨同类相残和集团内捕食作用的影响

明确不同猎物及密度下巴氏新小绥螨Neoseiulus barkeri与拉戈钝绥螨Amblyseius largoensis(Muma)的同类相残和集团内捕食作用,为其协同应用控制橡胶树害螨提供依据.在室温27±1℃、湿度75％±5％、光周期12 L∶12D 条件下,以六点始叶螨 Eotetranvchus sexmaculatus(Riley)、比哈小爪螨Oligonychus biharen(Hirst)和东方真叶螨Eutetranychus orientalis(klein)为集团外猎物,观察巴氏新小绥螨和拉戈钝绥螨对集团内和集团外猎物的捕食选择行为,以及不同集团外猎物密度下两种捕食螨对同种和异种捕食螨的捕食作用.巴氏新小绥螨和拉戈钝绥螨对异种个体及集团外不同猎物的捕食偏好性及捕食时间存在明显差异.巴氏新小绥螨偏好取食集团外猎物,异种捕食螨拉戈钝绥螨残存率达到80.00％以上;拉戈钝绥螨偏好取食集团外猎物六点始叶螨和比哈小爪螨,而当东方真叶螨存在时,其更偏好取食异种捕食螨巴氏新小绥螨(残存率为26.67％);发生集团内捕食时,拉戈钝绥螨为集团内捕食者,而巴氏新小绥螨为集团内猎物.集团外猎物密度可显著影响巴氏新小绥螨和拉戈钝绥螨相残作用,尤以猎物六点始叶螨对巴氏新小绥螨和东方真叶螨对拉戈钝绥螨影响最为明显,其充足时比无猎物时捕食量分别下降了 68.85％和62.90％.巴氏新小绥螨和拉戈钝绥螨的集团内捕食分别以比哈小爪螨和六点始叶螨的影响最大,猎物充足时比无猎物时捕食量下降了 80.00％和69.44％,但拉戈钝绥螨在以东方真叶螨为猎物时集团内捕食受猎物密度影响较小,猎物充足时取食量与猎物不足时接近,比无猎物时捕食量只下降20.83％.集团外猎物六点始叶螨、比哈小爪螨存在时,巴氏新小绥螨和拉戈钝绥螨表现为偏好选择集团外猎物,密度增加对两种植绥螨的同类相残和集团内捕食作用有明显抑制作用,但东方真叶螨充足与否,拉戈钝绥螨对巴氏新小绥螨的集团内捕食作用影响差异不显著.

Effects of prey species and density on cannibalism and intraguild predation of predacious mites Neoseiulus barkeri and Amblyseius largoensis

The study aims to clarify the cannibalisms and intraguild predations of Neoseiulus barkeri and Amblyseius largoensis with different spider mite species and densities. This knowledge will allow us to establish a reasonable predacious mite combination for biological control of major spider mites on rubber trees. Under the condition of 27°C, 70%±5% humidity, and photoperiod 12 L: 12 D, the predilections between spider mite predation and intraguild predation of N. barkeri and A. largoensis were assessed. Afterwards, the effects of spider mite species and density on intraguild predations and cannibalisms of two predators were evaluated. The predation preferences and consuming times for spider mite predations and intraguild predations of two predacious mites were different. N. barkeri preferred always spider mites, the survival rate of A. largoensis is more than 80.00% compared to all spider mites. However, A. largoensis preferred spider mites, only when Eotetranychus sexmaculatus or Oligonychus biharen existed. In case, Eutetranychus orientalis existed, it preferred to prey on N. barkeri (survival rate: 26.67%). In the intraguild predation interaction of two predacious mites, A. largoensis seems the predator and N. barkeri was likely the prey. The cannibalisms of N. barkeri and A. largoensis significantly decreased when spider mites existed, especially when sufficient numbers of E. sexmaculatus and O. biharen were provided to N. barkeri and A. largoensis, respectively, the cannibalisms decreased 68.85% and 62.90% compared to spider mite absent. Similarly, the intraguild predations of N. barkeri and A. largoensis decreased when spider mites existed, especially when sufficient numbers of O. biharen and E. sexmaculatus were provided to N. barkeri and A. largoensis, the intraguild predations of N. barkeri and A. largoensis decreased 80.00% and 69.44% compared to spider mite absent. However, the density of E. orientalis did affected the intraguild predation of A. largoensis on N. barkeri. When sufficient number of E. orientalis was provided, the predation number of A. largoensis on N. barkeri decreased only 20.83% compared to spider mite absent. When the spider mites E. sexmaculatus and O. biharen existed, both predacious mites preferred spider mites than intraguild predation. The increase of spider mite densities could decrease both cannibalisms and intraguild predations of the two predacious mites. However, E. orientalis and its density have only limited influence on the intraguild predation of A. largoensis on N. barkeri.