稻田穗期主要捕食性天敌对两种盲蝽集团内捕食的初步研究

【目的】集团内捕食是影响农业系统广食性天敌对靶标害虫控制作用的重要因素,全面揭示稻田广食性天敌对稻飞虱重要天敌黑肩绿盲蝽Cyrtorhinus lividipennis Reuter和中华淡翅盲蝽Tytthus chinensis(St?l)(半翅目:盲蝽科)的集团内捕食作用有助于更好地保护利用天敌。【方法】建立以两种盲蝽为猎物对象的种特异性二重定量PCR系统,检测比较不同抗性品种穗期田间主要捕食者对两种盲蝽的集团内捕食作用。【结果】(1)本研究建立的二重定量PCR具有的物种专化性,两种检测靶标灵敏度高且相似,可用于田间捕食者猎物分析;(2)感虫水稻品种上捕食者对盲蝽的捕食强度高于抗性水稻品种;不同种类捕食者对盲蝽的集团内捕食强度有显著差异;捕食者对黑肩绿盲蝽集团内捕食强度显著高于中华淡翅盲蝽。【结论】捕食性盲蝽在稻田生态系统遭遇集团内捕食,其集团内捕食强度与水稻品种抗性、捕食者种类和猎物丰富度有关。

Preliminary study of intraguild predation by generalist predators on two mirids in ear-stage paddy fields

Objectives] Intraguild predation (IGP) plays a crucial role in regulating the abundance of predators of crop pests in agroecosystems. The conservation and utilization of important predators of rice planthoppers, the green mirid bug (Cyrtorhinus lividipennis Reuter) and the black mirid bug [Tytthus chinensis (St?l)] (Hemiptera: Miridae), could be improved by better understanding of IGP on these species in the rice ecosystem. [Methods] A duplicate, species-specific, quantitative PCR for these two species was established to test and compare the magnitude of IGP by different predators in paddy fields planted with 2 rice varieties with different levels of resistance to rice planthoppers. [Results] (1) The PCR had high specificity and similar sensitivity to both mirid species and could therefore be used to quantitatively measure the level of IGP. (2) Generalist predators collected from susceptible rice fields showed significantly higher levels of IGP on the green mirid bug compared to those from resistant rice fields. The level of predation on the green mirid bug was significantly different among different the generalist predator species tested, and was significantly higher than that on the black mirid bug. [Conclusion] The relative magnitude of IGP on two mirids in rice fields can be related to host plant resistance to planthoppers, the species of generalist predators present, as well as prey species richness.