两种杀虫剂对稻田捕食性天敌集团捕食功能的影响

将稻田各类捕食性天敌作为一集团,运用功能法评价了甲胺磷和杀虫双对该集团捕食功能的影响,由于各类捕食性天敌对杀虫剂敏感性的不同,甲胺磷和杀虫双造成的各类天敌的死亡率和残存天敌个体的捕食功能减退率均不同。实验表明,隐翅虫类和狼蛛类对甲胺磷较为敏感,而对杀虫双,肖蛸类最为敏感。杀虫双对隐翅虫类的致死作用及捕食功能影响较小。就集团的捕食功能而言,甲胺磷影响明显大于杀虫双,但在总的功能减退率组分中,甲胺磷致     

稻田主要捕食性天敌的栖境生态位与捕食作用分析

本文进行了稻田捕食性天敌与稻飞虱的栖境生态位调查,并应用正交试验设计、添加试验法和排除试验法研究了?物种的栖境生态位与各天敌捕食作用的关系,结果表明：在5种灭敌与2种害虫共存系统中,天敌对褐飞虱Nilaparvata lugens Stal捕食量的正主效应大小依次为： 粽管巢蛛 Clubiona aponicola、青翅蚁形隐翅虫Paederus fuscipes、前齿肖蛸Tetragnatha praedonia、食虫沟瘤蛛 Ummeliata insecticeps,拟水狼蛛Pirata subpiraticus的负主效应值最大(随狼蛛密度增大捕食量下降);对稻纵卷叶螟Cnaphlocrcis medinalis Guenee捕食量正主效应大小依次为： 粽管巢蛛、肖蛸、青翅蚁形隐翊虫。多物种共存系统中,狼蛛、微蛛、跳蛛主要捕食飞虱;肖蛸主要捕食稻纵卷叶螟;管巢蛛对两种害虫均具有较好的控制作用。这与各物种的生态位宽度值相一致。当飞虱密度在每穴10一30头时,多物种共存系统优良的生物序是拟水狼蛛、食虫瘤胸蛛、青翅蚁形隐翅虫各为l头,棕管巢蛛2头,此时天敌的控制作用最大。添加法和排除法试验结果表明在具-定数量的多物种共存系统中,再增加天敌密度不一定能增加猎物的被捕食数,其直接的生物学原因是种间种内干扰(包括种间种内残杀)     

拟水狼蛛在水稻与茭白田之间的转移

拟水狼蛛Pirata subpiraticus是稻田飞虱及其它害虫的主要捕食性天敌。研究表明,拟水狼蛛在水稻移栽后从茭白田大量迁入稻田,而水稻收割前后则转移回茭白田。元素标记试验显示其转移最大距离可达40 m以上。稻田附近的茭白田是拟水狼蛛的主要避难地之一。铷元素直接标记和释放可作为监测捕食性天敌在生境间转移的新方法。     

中稻田三种飞虱的捕食性天敌优势种及农药对天敌的影响

对两优0923非防治的中稻田白背飞虱、灰飞虱和褐飞虱与其天敌间的关系,采用灰色关联度法、生态位分析方法,对盆拍法调查的3种飞虱与其捕食性天敌在数量、时间和空间三方面关系进行分析,对每一种天敌对应的关联度、生态位重叠指数和相似性比例等参数标准化后的密切指数相加,按照密切指数值之和大小排序,评判3种飞虱捕食性天敌优势种.并用同样方法分析常规防治田农药对飞虱捕食性天敌的影响,以期为合理施药,科学保护和利用天敌优势种提供科学依据,其结果是,非防治田白背飞虱前三位天敌是条纹蝇虎、草间小黑蛛和锥腹肖蛸;灰飞虱的是八斑球腹蛛、茶色新园蛛和锥腹肖蛸;褐飞虱的是纵条蝇狮、四点亮腹蛛和黑肩绿盲蝽.防治田白背飞虱前三位天敌是条纹蝇虎、草间小黑蛛和锥腹肖蛸;灰飞虱的是拟水狼蛛、四点亮腹蛛和草间小黑蛛;褐飞虱的是黑肩绿盲蝽、拟水狼蛛和四点亮腹蛛.盆拍法的防治田和非防治田之间3种飞虱前三位的相同天敌,白背飞虱完全相同,灰飞虱没有相同天敌,褐飞虱的是黑肩绿盲蝽和四点亮腹蛛.飞虱与天敌在时间和数量关系上,扫网法的防治田和非防治田之间3种飞虱前三位的相同天敌,白背飞虱的是锥腹肖蛸和四点亮腹蛛,灰飞虱完全相同,褐飞虱的是纵条蝇狮和条纹影虎.两种稻田的差异主要是农药杀伤了飞虱,使飞虱数量减少,并对天敌有一定杀伤力,进而影响到天敌的发生规律.非防治田的盆拍法和扫网法之间,3种飞虱前三位相同的天敌,白背飞虱的是锥腹肖蛸,灰飞虱的也是锥腹肖蛸,褐飞虱的是纵条蝇狮.防治田两调查方法结果之间,白背飞虱的是锥腹肖蛸,灰飞虱和褐飞虱前3位天敌中没有相同天敌,其差异主要是两法调查稻株的部位不同所致.     

水稻-褐飞虱-拟水狼蛛食物链的定量研究

应用荧光物质稀土元素铕示踪法对水稻褐飞虱拟水狼蛛食物链进行了定量分析研究。所施荧光物质的三种浓度20 mg/L、50 mg/L和100 mg/L 均为有效浓度,对水稻生长无可见的影响,孕穗期、抽穗期、乳熟期和黄熟期四个生育期水稻、褐飞虱和拟水狼蛛的荧光物含量均随所施荧光物质浓度的增高而增高。褐飞虱对不同生育期水稻的取食量依次为抽穗期>孕穗期>乳熟期>黄熟期,分别为每克褐飞虱生物量在24 h内摄食水稻17.5910 g, 17.4510 g, 13.8290 g和8.7070 g。拟水狼蛛对褐飞虱的捕食量为乳熟期>孕穗期>抽穗期>黄熟期,分别为每克拟水狼蛛生物量24 h捕食褐飞虱3.6380 g, 3.0830 g, 3.0770和2.8000 g。根据田间调查数据换算为每头拟水狼蛛捕食褐飞虱在孕穗期、抽穗期、乳熟期和黄熟期分别为11头、11头、13头和10头。     

低剂量农药作用下拟环纹豹蛛对褐飞虱的功能反应及搜寻行为

在室内研究了低剂量农药作用下拟环纹豹蛛对褐飞虱的功能反应及搜寻行为。结果表明,拟环纹豹蛛对褐飞虱的功能反应均符合Holling Ⅱ模型,且在最适的低剂量农药(V_药∶V_水为2∶5 000甲胺磷,12∶5 000杀虫双和1∶20烯丙菊酯)刺激下,蜘蛛捕食褐飞虱的数量是最多的,蜘蛛用于对1头褐飞虱进行制服和取食等活动所需的时间（处理猎物时间,Th）短,仅分别为未经农药处理的蜘蛛所需时间的0.45、0.32和0.35倍;而施用较高剂量8∶5 000的甲胺磷、28∶5 000的杀虫双和6∶20的烯丙菊酯的蜘蛛,处理猎物时间长得多,依次是经最适低剂量3种农药作用的蜘蛛所用时间的9.70、13.60和13.62倍。拟环纹豹蛛在稻株上的搜寻行为属非随机搜索型,在相同的低剂量农药作用下,蜘蛛的搜寻效应随飞虱密度的增加而下降;但在相同的猎物密度下,蜘蛛的搜寻效应与使用的农药浓度有密切的关系,在上述最适低剂量农药作用下,豹蛛对猎物的寻找效应最佳,其在稻株上的总滞留时间依次是未施药情形的1.56、1.49、1.48倍,总搜寻距离依次是未施药情形的1.36、1.42、1.39倍。据此,进一步证实了低剂量农药增强了稻田蜘蛛的控虫效能和对害虫的相对活力。     

用ELISA方法评价捕食性天敌对白背飞虱的捕食效能

用酶联免疫吸附试验（ELISA）方法测定了9类捕食性节肢动物对白背飞虱的捕食阳性反应率,定量评价了拟水狼蛛对白背飞虱的捕食效能。结果表明：活动能力强,与稻飞虱生境相似的捕食性天敌种类表现出较高的阳性反应率;拟水狼蛛对白背飞虱的捕食效率随水稻的生长而加强,在水稻生长后期,分别为21.53％和43．08％。     

利用分子探针法研究稻田蜘蛛集团对褐飞虱的捕食作用

为褐飞虱Nilaparvata lugens（Stal）的绿色防控提供理论参考依据,于2011年和2012年在调查了浙江富阳不同品种稻田褐飞虱和蜘蛛的发生密度后,利用荧光定量PCR分子探针技术分析了9科27种3 807头蜘蛛对褐飞虱的捕食作用。研究结果表明,在水稻Oryza sativa L.不同生育期,稻田总的褐飞虱和蜘蛛密度等参数值均随调查时间呈规律性变化,且在调查时间点间出现了显著性差异（P<0.05）;各科蜘蛛对褐飞虱的捕食阳性率均随水稻生育期的发展呈增加趋势,整体上,狼蛛科Lycosidae、皿蛛科Linyphiidae、球腹蛛科Theridiidae、肖蛸科Tetragnathidae、跳蛛科Salticidae和园蛛科Araneidae捕食率在DAT21,DAT35和DAT77,DAT91之间有显著性差异（P<0.05）;2012年两品种稻田的褐飞虱和蜘蛛密度等参数值均显著高于2011年的值,两年间汕优63（SY63）稻田的褐飞虱和蜘蛛密度均显著高于IR64的密度;2012年各科蜘蛛对褐飞虱的捕食阳性率显著高于2011年的值（P<0.05）,且狼蛛科和球腹蛛科对褐飞虱的捕食阳性率在两品种间存在显著性差异（P<0.05）;稻田4种蜘蛛优势种拟环纹豹蛛Pardosa pseudoannulata (Bosenberg & Strand)、八斑球腹蛛Theridion octomaculatum (Boes. et Str.）、食虫瘤胸蛛Oedothorax insecticeps (Boes. et str.)和锥腹肖蛸Tetragnatha maxillosa (Thoren)的捕食阳性率均随褐飞虱种群密度的增加而增加,该捕食功能反应曲线可用非线性模型P=aN/(1+bN)拟合;除锥腹肖蛸外,其它3种的捕食功能反应曲线均呈饱和状态;拟环纹豹蛛捕食褐飞虱的DNA残留量显著高于八斑球腹蛛、锥腹肖蛸和食虫瘤胸蛛的残留量（P<0.05）。本研究结果充分说明稻田各蜘蛛类群对不同生育期、不同品种水稻的褐飞虱均具有较强的捕食作用,是生物防治策略中的重要因素,应加强田间蜘蛛的保护工作和增强自然天敌的控害功能。     

稻田节肢动物群落优势功能集团的垂直分布、数量动态及天敌作用估计

研究了稻田节肢动物群落中优势功能集团的垂直空间分布和数量动态规律。结果表明,狼蛛的分布范围不象过去认识的那样广,而是主要分布在稻株的中下部。蛸蛛也不仅仅限制在稻株叶冠层,其在受到农药干扰后,向下部转移。顶位物种与基位物种垂直空间分布的相关性不大。在稻田内影响天敌对褐飞虱种群动态控制作用大小的因素,除了天敌的数量之外,若有天敌与褐飞虱的空间分布特征,褐飞虱占天敌食谱中的比例等。提出了包含天敌、褐飞虱     

扑虱灵对稻飞虱及其捕食性天敌种群的影响

扑虱灵对稻飞虱的防治效果,及对捕食性天敌的毒性,进行了田间试验,并与叶蝉散,杀虫双的使用结果作比较．试验结果表明,扑虱灵对稻飞虱的防治效果达93％,与叶蝉散,杀虫双相比较。防治效果提高了2．39～32．85％．对黑肩绿盲蝽和蜘蛛种群具有不同程度的选择性,维护较低的稻飞虱与天敌的比值,有利于天敌作用的发挥,维持对稻飞虱较长的残效期,基本上可以控制稻田后期飞虱的增长．     

稻田节肢动物群落的多样性及对褐飞虱的控制功能

对江苏江浦及安徽安庆两地五种类型稻田的节肢动物群落生物多样性研究表明,以对褐飞虱Nilaparvata lugens具有抗性的粳稻田多样性指数最高。稻田蜘蛛亚群落与褐飞虱种群数量变化间存在明显的相关性,11年中64%的年份表现为显著相关。利用天敌功能指数EF=（E+P）^E/P、数值反应的方法研究了稻田蜘蛛功能团与褐飞虱种群间的生存、繁殖和数量关系,结果表明,初始EF值与褐飞虱对水稻的危害率及褐飞虱种群的未来最大饱和容量K值间呈显著相关。本文讨论了利用初始EF值来预测天敌对害虫的功能作用及生物防治与化学防治协调的可能性。     

蚊幼对狼蛛的营养作用研究

研究蚊子幼虫（子孓）以拟水狼蛛（Ｐｉｒａｔａｓｕｂｐｉｒａｔｉｃｕｓ）的营养,繁殖作用,结果表明狼蛛对蚊幼的捕食符合ＨｏｌｌｉｎｇⅡ型功能反应,喂以蚊幼和不喂蚊幼处理狼蛛的体重增长率和生殖有极显著差异,在相同蚊幼密度下,狼蛛初始体重越小,增长率越大,经计算狼蛛每增重１ｍｇ,需消耗１０．５８ｍｇ蚊幼,这基本符合生态系统营养级能量流动的１／１０法则,狼蛛体重大小对褐飞虱的捕食量有明显差异,体重大的个体     

Intra-guild predation relaxes natural enemy impacts on herbivore populations

Abstract. 1. To investigate the role of intra-guild predation in mediating the impact of the natural enemy complex on herbivore populations, a manipulative field experiment was conducted using uncaged plots (islets of Spartina cordgrass) on a North American salt marsh. The densities (moderate or low) of two invertebrate predators, the generalist wolf spider Pardosa littoralis and the specialist mirid bug Tytthus vagus , were manipulated in a 2 × 2 factorial design, and the resulting treatment effects on the population growth of their herbivorous prey, Prokelisia planthoppers, were assessed.
2. The abundance of wolf spiders on experimental islets was unaffected by the presence of mirid bugs, however the density of mirid bugs was influenced very negatively by the presence of the wolf spider.
3. The negative effect of the wolf spider on mirid bugs most probably resulted from the intra-guild predation of mirids by spiders because planthopper limitation by the wolf spider alone was significantly greater than when both predators were present.
4. As a result of intra-guild predation, planthopper population growth was positive in the presence of both predators, despite the fact that each predator alone promoted a decrease in planthopper population growth.
5. Notably, the occurrence of intra-guild predation diminished top-down impacts on planthopper populations in a relatively simple food web where strong top-down effects were expected. This result, however, was limited to habitats on the marsh with simply structured vegetation lacking leaf litter.     

Effect of insecticides on mealybug destroyer (Coleoptera: Coccinellidae) and parasitoid Leptomastix dactylopii (Hymenoptera: Encyrtidae), natural enemies of citrus mealybug (Homoptera: Pseudococcidae)

In this study, we measured, under laboratory conditions, the direct and indirect effects of insecticides on mealybug destroyer, Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae), and parasitoid Leptomastix dactylopii Howard (Hymenoptera: Encyrtidae), natural enemies of citrus mealybug, Planococcus citri (Risso) (Homoptera: Pseudococcidae). The adult stages of both natural enemies were exposed to sprays of the insecticides buprofezin, pyriproxyfen, flonicamid, acetamiprid, dinotefuran, and clothianidin at label-recommended rates to assess direct mortality after 24, 48, and 72 h, respectively. The effects of the insecticides on L. dactylopii parasitization rate and percentage of parasitoid emergence also were monitored using the label and 4x the recommended label rate. Dinotefuran was extremely detrimental to the adult parasitoid at the label rate with 100% mortality after 24 h. Buprofezin, pyriproxyfen, and flonicamid were not harmful to L. dactylopii when applied at the label rate. At 4x the recommended label rate, dinotefuran, acetamiprid, and clothianidin were all harmful to the parasitoid with 100% mortality 72 h after application. Both buprofezin and flonicamid were not toxic to L. dactylopii with 100% adult survival after 72 h. Pyriproxyfen and flonicamid, at both the label and 4x the recommended label rate, did not negatively affect L. dactylopii parasitization rate or percentage of parasitoid emergence. Acetamiprid, dinotefuran, and clothianidin were toxic to C. montrouzieri adults with 100% mortality after 48 h, whereas buprofezin, pyriproxyfen, and flonicamid demonstrated minimal (10-20% mortality after 48 h) harmful effects to the predator. Based on the results from our study, the indirect effects of the insect growth regulator (IGR) buprofezin were not decisive; however, the IGR pyriproxyfen and the insecticide flonicamid were not directly or indirectly harmful to the predator C. montrouzieri and parastioid L. dactylopii, indicating that these insecticides are compatible with both natural enemies when used together for control of citrus mealybug in greenhouses and conservatories.     

Effects of three insecticides on adult bionomics of the parasitoid Encarsia formosa

Pesticides can negatively affect many life history traits of natural enemies. In this study, we studied the effects of three insecticides with different modes of action on the bionomics of Encarsia formosa, a parasitoid of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Buprofezin (800 mg (a.i.)/L) and pyriproxyfen (50 mg (a.i.)/L) were selected among IGRs, while fenpropathrin (250 mg (a.i.)/L) was selected from the Pyrotheroids. Adults of E. formosa were treated via exposure to residues of insecticides on leaf discs. Our results revealed that buprofezin and pyriproxyfen did not affect longevity and fecundity, while fenpropathrin significantly reduced the longevity and fecundity of treated wasps. Results of logistic regression revealed that control, buprofezin- and pryproxyphen-treated E. formosa was a function of host density and followed a type II functional response. In contrast, E. formosa treated by fenpropathrin showed a type III functional response. Estimated attack rate for buprofezin and pyriproxyfen did not differ significantly from the control, whereas fenpropathrin-treated wasps showed a lower attack rate than the control. According to the obtained results, handling time of fenpropathrin-treated wasps was significantly higher (4.57 ± 0.5) than the control (2.83 ± 0.35). Our results showed that the maximum parasitism rate achieved by control wasps was 8.39, while the rate for buprofezin-, pyriproxyfen- and fenpropathrin-treated wasps was 6.99, 7.69 and 5.25, respectively. Overall, results suggest that buprofezin and pyriproxyfen can be used in an integrated pest management programme or biological control programme without destructive effects on the efficiency of this natural enemy in green houses.     

稻田节肢动物群落的多样性及对褐飞虱的控制功能

对江苏江浦及安徽安庆两地五种类型稻田的节肢动物群落生物多样性研究表明,以对褐飞虱Nilaparvata lugens具有抗性的粳稻田多样性指数最高。稻田蜘蛛亚群落与褐飞虱种群数量变化间存在明显的相关性,11年中64%的年份表现为显著相关。利用天敌功能指数EF=（E+P）^E/P、数值反应的方法研究了稻田蜘蛛功能团与褐飞虱种群间的生存、繁殖和数量关系,结果表明,初始EF值与褐飞虱对水稻的危害率及褐飞虱种群的未来最大饱和容量K值间呈显著相关。本文讨论了利用初始EF值来预测天敌对害虫的功能作用及生物防治与化学防治协调的可能性。     

Natural enemies of herbivores maintain their biological control potential under short‐term exposure to future CO2, temperature,and precipitation patterns

Climate change will profoundly alter the physiology and ecology of plants, insect herbivores, and their natural enemies, resulting in strong effects on multitrophic interactions. Yet, manipulative studies that investigate the direct combined impacts of changes in CO₂, temperature, and precipitation on the third trophic level remain rare. Here, we assessed how exposure to elevated CO₂, increased temperature, and decreased precipitation directly affect the performance and predation success of species from four major groups of herbivore natural enemies: an entomopathogenic nematode, a wolf spider, a ladybug, and a parasitoid wasp. A four‐day exposure to future climatic conditions (RCP 8.5), entailing a 28% decrease in precipitation, a 3.4°C raise in temperature, and a 400 ppm increase in CO₂ levels, slightly reduced the survival of entomopathogenic nematodes, but had no effect on the survival of other species. Predation success was not negatively affected in any of the tested species, but it was even increased for wolf spiders and entomopathogenic nematodes. Factorial manipulation of climate variables revealed a positive effect of reduced soil moisture on nematode infectivity, but not of increased temperature or elevated CO₂. These results suggest that natural enemies of herbivores may be well adapted to short‐term changes in climatic conditions. These findings provide mechanistic insights that will inform future efforts to disentangle the complex interplay of biotic and abiotic factors that drive climate‐dependent changes in multitrophic interaction networks.     

Natural enemy impacts on Bemisia tabaci (MEAM1) dominate plant quality effects in the cotton system

1. Plant quality (bottom‐up effects) and natural enemies (top‐down effects) affect herbivore performance. Furthermore, plant quality can also influence the impact of natural enemies. 2. Lower plant quality through reduced irrigation increased the abundance of the cryptic species from the Bemisia tabaci complex [hereafter B. tabaci Middle East Asia Minor 1 (MEAM1)], but not its natural enemies on cotton. It was therefore predicted that lower plant quality would diminish the impact of natural enemies in regulating this herbivore. 3. Over three cotton seasons, plant quality was manipulated via differential irrigation and natural enemy abundance with insecticides. Life tables were used to evaluate the impact of these factors on mortality of immature B. tabaci (MEAM1) over nine generations. 4. Mortality of B. tabaci (MEAM1) was consistently affected by natural enemies but not by plant quality. This pattern was driven by high levels of sucking predation, which was the primary (key) factor associated with changes in immature mortality across all irrigation and natural enemy treatments. Dislodgement (chewing predation and weather) and parasitism contributed as key factors in some cases. Analyses also showed that elimination of sucking predation and dislodgement would have the greatest effect on overall mortality. 5. The top‐down effects of natural enemies had dominant effects on populations of B. tabaci (MEAM1) relative to the bottom‐up effects of plant quality. Effects were primarily due to native generalist arthropod predators and not more host‐specific aphelinid parasitoids. The findings of this study demonstrate the important role of arthropod predators in population suppression and validate the importance of conservation biological control in this system for effective pest control.     

Pyriproxyfen controls silverleaf whitefly, Bemisia tabaci (Gennadius), biotype B (Homoptera: Aleyrodidae) (SLW) better than buprofezin in bitter melons Momordica charantia L. (Cucurbitaceae)

To improve compatibility between chemical and biological controls, the use of selective insecticides such as insect growth regulators (IGRs) is crucial. In cucurbits, the use of pyriproxyfen (an IGR) has been shown by others to be an effective method of reducing the number of sap-sucking insects, especially silverleaf whitefly, Bemisia tabaci (Gennadius) Biotype B (SLW). Therefore, we compared pyriproxyfen and buprofezin (an IGR) with that of no treatment (control) in a bitter melon crop for the control of populations of SLW and for their effects on fruit production. Pyriproxyfen controlled SLW and tended to have heavier fruits than the control treatment and reduced the abundance of nymphs and exuvia. Buprofezin showed no evidence in controlling SLW compared with the pyriproxyfen and control treatments. Neither pyriproxyfen nor buprofezin had any effect on the number of harvested fruit or overall fruit yield, but the average weight per fruit was higher than the control treatment. Pyriproxyfen was effective in controlling whitefly populations in bitter melons, and both pyriproxyfen and buprofezin may have the potential to increase yield. Their longer-term use may increase predation by natural enemies as they are species-specific and could favour build up of natural enemies of SLW. Thus, the judicious use of pyriproxyfen may provide an effective alternative to broad-spectrum insecticides in small-scale cucurbit production.