【作者】 钱萍；

【导师】 祝增荣；

【作者基本信息】 浙江大学 ， 农业昆虫与害虫防治， 2020， 博士

【摘要】 飞虱、叶蝉和螟虫为取食水稻的三大类植食性昆虫,特别是三种主要稻飞虱(褐飞虱Nilaparvata lugens、白背飞虱Sogatella furcifera和灰飞虱Laodelphax striatellus)长期以来为水稻上的首要害虫,通过刺吸水稻汁液和传播病毒病等对水稻产量产生威胁。全世界90%的水稻产量都来自亚洲,而中国需要用13%的世界耕地面积养活19%的世界人口,压力不可谓不大,如何从“虫口夺粮”来保证粮食产量一直是农业工作者的首要任务。随着害虫抗药性的发展和杀虫剂副作用的日益严重,生物防治和生态工程在害虫治理中的应用受到越来越多的重视。本文通过多年的大田实验对不使用杀虫剂、保留天敌源田埂上原生植物、种植显花植物等生态功能植物和稻鸭共育等多种生态工程措施在水稻害虫治理中的作用进行了实证研究,并通过详细的分析尝试揭示其生态学机理,得到如下结果:(1)通过保留田埂植被增加了天敌源的植被多样性和天敌的补充食物资源。不同的实验处理中田埂上的植物多样性差异显著,有机稻田、种花稻田的田埂植物多样性显著高于使用除草剂的常规稻田。在群落结构上有机管理的稻田中田埂植被以花期与水稻生长季节重叠的有益植物为主,而常规稻田的田埂上则是飞虱寄主植物数量较多,特别是在除草剂使用90天之后。天敌源-田埂上的植物可以为天敌提供栖息地和庇护所,而有益植物比例的增加提供了丰富的花粉和花蜜,可以作为天敌的补充食物,有利于天敌种群的建立和发展。(2)生态功能植物(显花植物和载体植物)对飞虱寄生性天敌的吸引作用。黄板调查结果显示种花田种植显花植物的区域中缨小蜂(Mymaridae)数量显著高于对照田相应区域,且缨小蜂有从稻田向显花植物迁移的趋势,说明了显花植物对寄生性天敌有吸引作用。载体植物游草Leersia sp.对缨小蜂也有一定的吸引作用,与水稻田相比,游草区域的缨小蜂数量更多。茭白Zizania latifolia上的长绿飞虱Saccharosydne procerus为培育寄生蜂提供了丰富的食物资源,我们在茭白上同时发现了数量较多的缨小蜂和飞虱攀金小蜂(稻虱食卵金小蜂)Panstenon oxylus,两种寄生蜂在茭白田和邻近水稻田中的分布情况和迁移方向都有所不同。茭白田中田边缘的金小蜂数量大于田内部,与在水稻田中的情况相反;而缨小蜂在茭白田边缘的数量大于内部,在水稻田边缘数量小于内部;在迁移方向上,金小蜂有从茭白田向水稻田迁移的趋势,缨小蜂的迁移方向则是由水稻田向茭白田。此外茭白田和水稻田中植食性节肢动物的群落相似性低于自然天敌,说明两种作物相邻种植不会导致目标害虫的增加,且可以互为天敌源-库(源-汇),增加天敌在两种生境中的交流,同步促进对两种作物上害虫的自然防治。(3)保留田埂天敌源的植被多样性和种植显花植物能显著增加稻田天敌库(汇)内捕食性天敌的数量,而杀虫剂的使用对天敌种群有负面影响。稻田内的捕食性天敌种群密度与田埂上的植物多样性显著正相关,而水稻分蘖盛期的植食性昆虫数量与植物多样性负相关,说明田埂上非水稻植物的存在有助于增加天敌数量、降低害虫数量。通过在非稻田天敌源区域种植四种长花期显花植物,稻田天敌库内蜘蛛、蜻蜓等捕食性天敌的数量得到了显著提高,但寄生性天敌受到的影响较小。杀虫剂的使用对捕食性天敌的副作用存在累积/延迟效应,前期常规田的捕食性天敌数量与有机田中的数量没有显著差异,但水稻孕抽穗期常规田的捕食性天敌数量显著低于有机田中的数量。杀虫剂对寄生性天敌数量影响较小,但显著降低了其多样性。三种处理中飞虱和叶蝉等植食性昆虫的种群密度在水稻生长早期没有显著差异,在孕抽穗期非施药田中飞虱和叶蝉的数量显著高于常规田中的虫量,但未超过经济阈值。在节肢动物群落组成上,有机田和种花田中金小蜂、姬小蜂等小蜂总科的寄生蜂数量高于其他寄生蜂的数量,而常规田中茧蜂的数量因稻纵卷叶螟的虫量较高而较高。(4)稻鸭共育在害虫控制上有一定限制且降低了田间捕食性天敌的数量,但对稻田内的杂草有较好的控制效果,并且通过生产销售有机大米和有机鸭肉能取得良好的经济效益。养鸭田中水稻茎秆和冠层上的捕食性天敌数量显著低于自然田,不利于对害虫的自然控制。特别是在孕抽穗期把鸭子赶出稻田后,稻田天敌库中天敌种类和数量稀少,对于害虫来说是一个“无敌”空间,导致了叶蝉和飞虱在养鸭田中虫量较高。稻鸭共育处理中稻田内部的稗草Echinochloa crusgalli等杂草在数量上显著低于自然处理,鸭子对杂草的相对防治效果与除草剂等同,而田埂植物作为自然天敌重要的栖息地和庇护所受鸭子的影响较小。经过有机认证或创立了生态品牌的产品在价格上远高于普通产品,本研究结果显示通过售卖有机大米和鸭肉显著提高了农民的净收益,养鸭田和自然田的净收益分别为常规田净收益的6.9~8.1倍和5.3倍,弥补了稻鸭共育高养鸭成本和低水稻产量带来的损失并取得了更高的经济效益。(5)影响水稻田飞虱和叶蝉从第四代到第五代种群增长率的关键外界生物因子主要为水稻生长早期田埂植物、非主要害虫猎物的丰度、天敌的丰度及多样性和后期田埂植物的多样性。实验期间,飞虱在水稻生长季节有明显的两个世代,第一代飞虱虫量在不同处理之间没有显著差异,第二代飞虱虫量在非施药田中较高,但种群增长率没有显著差异。叶蝉的虫量变化也可分为两个时期,前期(8月下旬之前)各处理中的虫量均保持在较低的水平,后期常规田中虫量显著低于其他处理,但种群增长率也没有显著差异。通过主成分分析和逐步回归模型的建立,确定了在所有影响两种半翅目主要害虫种群动态的外界生物因子中,田埂天敌源区域水稻生长早期(6~7月)的植物丰度和后期(8~9月)的植物多样性对稻飞虱和叶蝉具有较大的共同影响;飞虱种群增长率与早期稻田天敌库内天敌的多样性和后期中性昆虫(腐食者)种群密切相关;影响叶蝉种群增长率的关键因子为早期非叶蝉植食者、蜘蛛的丰度和9月田埂植物多样性。总的来说水稻生长早期的中性昆虫(腐食者)、非主要害虫植食者和田埂植被能为天敌提供替代猎物、栖息地和庇护所,有助于早期稻田内天敌库的建立,能增加天敌的数量和多样性,从而增强对稻飞虱和叶蝉种群的自然控制;而后期需要对中性昆虫和田埂植物的数量及多样性进行调控以避免增加害虫数量。综上所述,本文通过陷阱、扫网、黄板诱集等多种方法对平原水网稻区的节肢动物和植物进行了较为全面的调查,研究了保留天敌源(田埂)植物、种植显花植物、稻鸭共育以及不使用杀虫剂等多种生态工程措施在开放的大田环境中对控制水稻害虫种群和增加稻田内天敌数量的实际作用。研究结果显示尽管不同的生态工程措施对害虫和天敌的影响存在一定差异,但总体上来说不使用杀虫剂、种植显花植物并提高天敌源区域的植物多样性有利于增加景观多样性和稻田内天敌库中捕食性天敌的数量及寄生性天敌的多样性,增强对飞虱、叶蝉等植食性害虫的自然控制,提高水稻生态系统的稳定性。更多还原

【Abstract】 Planthoppers,leafhoppers and stem borers are three major phytophagous insects feeding on rice.The three main species of the rice planthoppers(Nilaparvata lugens,Sogatella furcifera and Laodelphax striatellus)are primary rice pests in recent decades and they threaten the rice yields by sucking phloem sap and transmitting virus diseases.Asia accounts for over 90 percent of the worlds rice production,and China,with only 13% of the world arable land need to feed 19% of the world population.Protecting adequate rice supply from pest losses has been a major task of agricultural workers.Pesticides have been the main tactic used to control pests but with the development of pesticide resistance and side effects such as threats to human and environmental health as well as inducing secondary pest development,biological control and ecological engineering that reduce insecticide use have attracted greater attention from researchers and farmers.This thesis reports three-years’ field experiments conducted to study the effects of various ecological engineering measures such as withholding insecticides,conserving bund vegetation,planting flowering plants in non-rice habitats which can act as natural enemy sources and rice-duck farming on rice pest management.The following results were obtained:(1)Conserving bund vegetation increased plant biodiversity and supplementary food source for natural enemies.There was significantly higher plant diversity in Organic and Flower treatments compared with the Conventional treatment that had used herbicides.In the fields under organic management,the plant community on the bunds were dominated by beneficial plants(the flowering period of which overlapped with the rice growing season),while planthopper host plants were the major plant groups in the conventional fields.The host plant density increased rapidly in the Conventional treatment especially after 90 days of the herbicide application.The vegetation on the paddy bund could provide habitats and shelters for natural enemies,high beneficial plant proportion provided abundant nectars and pollens as supplementary food,would help to establish and develop natural enemy population.(2)Attractive effects of eco-functional(flowering and banker)plants on hymenopteran natural enemies of planthoppers.Significantly higher numbers of Mymaridae wasps were found in areas where flowering plants were planted in the Flower treatment than in the same area of the control treatment.These parasitic wasps move from the rice towards flowering plants,indicating that the flowering plants were attracting them.One of the tested banker plants: Leersia sp.also had some attractive effects on the Mymaridae wasps as there were more parasitic wasps found in the banker plant area when compared with the rice field.Saccharosydne procerus on banker plant Zizania latifolia could have provided a rich food resource for the development of planthopper parasitic wasps.Abundant numbers of Mymaridae wasps and one species of Pteromalidae wasps(Panstenon oxylus)which fed on planthopper eggs were found on the Zizania plants.The distribution and movement directions of these two wasps were different in Zizania fields and adjacent rice fields.The abundance of Pteromalidae wasps in the Zizania fields was higher at the field edges than within the fields,while the opposite result was found in the rice fields.More Mymaridae wasps were found on the edges of the Zizania fields than within the fields,while the number of Mymaridae wasps was larger within the rice fields than on the edges.The movement directions of the Mymaridae wasps were from the rice towards the Zizania while it was the reverse with the Pteromalidae wasps.Furthermore,the community similarity of herbivores was lower than natural enemies between the two crop fields,indicating that the planting of Zizania latifolia adjacent to rice fields could increase the communication of natural enemies between the two habitats,and simultaneously promote the natural control function of pests of both crops.(3)The conservation of bund vegetation and planting of flowering plants significantly increased the abundance of predators while insecticides had negative effects on natural enemies.Significant positive relationships between the predator population density and bund plant diversity and negative correlation between herbivorous insect density and plant diversity were found,indicated that non-crop plants acted as main sources to help increase natural enemy abundance and reduce pest populations.The densities of spiders and dragonflies in Flower fields where 4 species of long flowering period and high pollen sugar content plants were planted were significantly higher than in the organic and conventional fields.There was a cumulative/delayed effect on the adverse impacts of pesticide use on predators.The predator density in conventional fields and organic fields in the early season showed no difference,but in the rice heading stage,the number of predators was significantly lower in the conventional fields than that in the organic fields.The experimental treatments had little influence on within paddy parasitoid densities,but the diversity was significantly reduced by insecticide applications.The populations of planthoppers,leafhoppers and total herbivores showed no difference between the three treatments at the early stages,and the significantly larger populations in the non-insecticide fields at the heading stage did not reach economic threshold levels.The above results indicated that withholding insecticides coupled with additional flowering plants could increase natural enemy population and had good control on pests in the early stages.The treatments had also some influences on the structure of arthropod communities.The abundance of Chalcidoidae wasps(i.e.Pteromalidae and Eulophidae)was higher than other parasitoid wasps in the non-insecticide fields.In the conventional fields,the Braconidae wasps were more abundant because of larger rice leaffolder populations.(4)Rice-duck farming was found to be overrated as a pest control tactic and it had negative impacts on the predatory natural enemies,but ducks had a good control on weeds within the paddies and rice-duck farming could gain great economic benefits through sale of organic products.The lower predator populations on the rice stem and canopies in the rice-duck farming seem to have weakened the natural control of rice pests.This is especially the case after the ducks were driven out of the paddy.Natural enemy abundance in the rice fields were low,implying that an “enemy-free space” might have been created for herbivores,especially the planthoppers and leafhoppers.The population densities of Echinochloa crusgalli and the total weeds within the rice fields were well suppressed by duck activities,indicating that ducks were effective at controlling weeds.But unlike herbicides,ducks had little effects on bund vegetation which were habitats and refugia for natural enemies.The price of rice and duck meat with organic certification or brand effect were much higher than ordinary products and thus the net incomes in rice-duck farming and natural farming were 6.9~8.1 and 5.3 times that of conventional farming,respectively,compensating for any deficiencies in rice-duck farming.(5)The key external biological factors influencing the population growth of planthoppers and leafhoppers were the early-season abundance of bund vegetation and non-pest herbivores,the early-season abundance and diversity of natural enemies and the late-season diversity of bund vegetation.There were two main planthopper generations throughout the rice growing season and the cumulative abundance of planthoppers in the first generation showed no difference in the four treatments.In the second generation however,the cumulative abundance of planthoppers in non-insecticide fields were significantly higher,although the population growth rates of planthoppers in different treatments showed no significant differences.The results of leafhoppers were similar,there were no significant differences in population growth rates despite significantly larger number of leafhoppers was captured in non-insecticide fields in the late season.The principal component analysis showed that among all external biological factors influencing planthoppers and leafhoppers’ population dynamics,the early-season(June and July)abundance and late-season(August and September)diversity of bund vegetation had big influence on both planthoppers and leafhoppers.The stepwise regression analysis showed that early-season diversity of natural enemies and late-season neutral insects had larger effects on planthopper population dynamics than other factors.The key factors influencing leafhopper population growth included the abundance of non-leafhopper herbivores and spiders in the early season and the diversity of bund vegetation in September.In general,the neutral insects(detritivores),non-pest herbivores and bund vegetation in the early season could help establish the initial natural enemy bank and increase their density and diversity by providing alternative food,habitats and shelters.While the late-season abundance and diversity of bund vegetation and detritivores should be manipulated to avoid increasing pest populations.In this research,multiple sampling methods(ground traps,net sweeping,and sticky trap etc.)were used to investigate the arthropods and plants in rice agroecosystem,and to study the effects of various ecological engineering measures on natural enemy population and pest control.The results showed that though different measures had different influences on the natural enemies and pests,in general,by not using insecticides,planting flowering plants and increasing bund(natural enemy source)plant diversity can be important management tactics.These practices can significantly increase the diversity of farmland landscape,abundance of predators and diversity of parasitoids in rice natural enemy sink,enhance the natural control function on planthoppers,leafhoppers,and improve the stability of rice ecosystem.更多还原