稻田稻飞虱卵寄生蜂群落的重建和维持

研究了综防区和非综防区稻田飞虱卵寄生蜂群落的重建和维持。结果表明：早稻生长期,稻虱缨小蜂Anagrus nilaparvatae 和拟稻虱缨小蜂 A. paranilaparvatae 在水稻移栽后第9天进入综防区稻田,在第13天进入非综防区稻田,同在第21天完成群落重建,重建速率分别是0.28种/天和0.21种/天。晚稻生长期,综防区和非综防区稻虱缨小蜂和拟稻虱缨小蜂均在水稻移植后第1天进田,至第21天完成群落重建,重建速率分别是0.12种/天和0.04种/天。维持阶段综防区群落较非综防区稳定。群落重建和维持受温度、种库中卵寄生蜂种类和数量、种库距稻田的远近、稻田中害虫种类和数量以及害虫防治策略的影响。     

茭白害虫长绿飞虱与稻田缨小蜂关系的研究

茭白害虫长绿飞虱 Saccharosydne procerus是稻虱缨小蜂Anagrus nilaparvatae 在稻田外的主要寄主之一。茭白田可为稻田提供大量的稻虱缨小蜂,从而提高对稻田稻飞虱的控制能力。从褐飞虱和长绿飞虱卵中羽化的稻虱缨小蜂均明显地选择寄生褐飞虱卵,对长绿飞虱卵的寄生率也较高。长绿飞虱在水稻上不能完成其生活史。因此,稻田和茭白田的合理布局可有效地提高稻田缨小蜂的数量,从而提高该寄生蜂对有关害虫的生防效益。     

不同生境源的稻飞虱卵寄生蜂对寄主的选择和寄生特眭

稻飞虱重要卵寄生蜂缨小蜂Anagrus flaveolus、A optabilis和寡索赤眼蜂Oligosita aesopi、O.Naias均能在稻田和稻田周围的非稻田生境中生存。而.Ftaveolus为优势种。不同生境来源的卵寄生蜂有着不同的寄生和选择特性。缨小蜂A.Flaveolus能在飞虱科内转换寄主,但需1～2代的适应期。寄主卵对寡索赤眼蜂O.Aesopi的寄生有较大的影响,用褐飞虱和黑尾叶蝉诱集的O.Aesopi呼;不能交叉寄生。稻田内诱集的寄生蜂选择稻飞虱,而杂草地中诱集的缨小蜂则对飞虱T.Pusanus有一定的选择性。非稻田生境对保护稻飞虱卵寄生蜂有很大的作用,但对其寄生特性有较大的影响。     

稻虱缨小蜂的寄主选择性和适宜性

稻虱缨小蜂Anagrus nilaparvatae Pang &Wang对白背飞虱Sogatella furcifera(HO· rvath)卵龄无明显的寄生选择性,但在新鲜寄主中的发育历期较短,育出的蜂体较大,生殖力较高,而羽化 率和雌雄性比则不受寄主卵龄的影响。在白背飞虱和褐飞虱Nilaparvata lugens (Stal)卵共存时,稻虱缨小蜂明显选择褐飞虱。稻虱缨小蜂在褐飞虱卵中的发育显著地比在白背飞虱卵中的慢;褐飞虱卵育出的 蜂的初羽化成虫怀卵量显著高于白背飞虱卯育出的,虫体大小也类似,且虫体越大,生殖力越高。从白背飞虱卵育出的蜂供给白背飞虱卵(W→W)时,产卵量低于其它育蜂寄主和供给产卵寄主组合(w→B、B→B、B→W)的,其内禀增长力rm较其余者小25%。本文还讨论了应用适宜性指数来综合衡量寄主的适宜性。     

水稻品种对稻虱缨小蜂发育、存活及繁殖的影响

水稻品种既能直接地经物理结构,亦能间接地通过改变褐飞虱Niladarvatalugens(Stal)卵的适宜性,影响稻虱缨小蜂Anagrus nilaparvatae Pang et Wang的发育、存活和繁殖。稻虱缨小蜂的羽化率、怀卵量分别与其寄主褐飞虱卵所处水稻品种叶鞘鞘脊的硅细胞密度呈极显著和显著负相关;同时,怀卵量和虫体大小还与受水稻品种影响的褐飞虱卵粒大小呈极显著正相关。稻虱缨小蜂种群增长能力指数的组分分析表明,不同水稻品种影响稻虱缨小蜂种群增长能力的主要因子不同,显示了水稻品种对稻虱缨小蜂影响的多因子作用。     

非稻田生境褐飞虱卵寄生蜂群落动态

对稻田周围田埂和路边上能寄生褐飞虱的卵寄生蜂群落的动态进行了初步研究。研究结果表明：冬季休耕期,卵寄生蜂群落变化趋势为先降后升;夏季休耕期,因为水稻收割,部分寄生蜂迁移到田埂和路边,卵寄生蜂数量呈直线上升趋势;早稻生长期,田埂和路边的飞虱卵寄生蜂的数量变化同稻田褐飞虱卵寄生蜂和褐飞虱呈正相关的关系;晚稻移栽后,田埂和路边上飞虱卵寄生蜂数量下降,以后在一定的范围内波动,晚稻后期,数量急剧上升随后很快下降,害虫防治史影响着稻田周围生境中8飞虱卵寄生蜂群落,综防区试验田周围生境中飞虱卵寄生蜂群落的寄生蜂数量、物种丰富度、多样性指数和均匀性指数均优于非综防区。     

不同营养源对稻虱缨小蜂寿命及寄生能力的影响

研究了蜂蜜、玉米花粉、大豆花、褐飞虱蜜露和黄脊飞虱蜜露对稻虱缨小蜂寿命、寄生能力以及寄生行为对稻虱缨小蜂寿命和存活率的影响。结果表明,蜂蜜、玉米花粉、褐飞虱蜜露和大豆花均能明显延长稻虱缨小蜂的寿命。并且显著地提高了对褐飞虱卵的寄生能力,其中蜂蜜最有效,大豆花次之,玉米花粉和褐飞虱蜜露这两种营养源以玉米花粉(水和褐飞虱蜜露+水的形式)对提高稻虱缨小蜂寿命最有效,而单一玉米花粉、花粉液、褐飞虱蜜露稀释液和纯褐飞虱蜜露均不能延长稻虱缨小蜂寿命,黄脊飞虱蜜露对稻虱缨小蜂的寿命和寄生能力均无影响。寄生行为对稻虱缨小蜂的寿命基本无影响。但致使其40～48h内的存活率提高,此后的存活率降低较快,在稻田周围的作物和植被上调查到约10种飞虱,非稻田生境能为稻田寄生性天敌提供寄主和食物,是理想的庇护所,对保护和提高稻田天敌种群数量,提高稻田天敌的生物控制作用。     

非稻田生境中稻飞虱卵寄生蜂群落结构研究

研究发现稻田周围田埂、路边禾本科杂草上栖息着能寄生于稻飞虱卵的寄生蜂有缨小蜂科和赤眼蜂科两类,它们是非稻田生境中稻飞虱卵寄生蜂群落的重要成员.群落中,缨小蜂科数量较多,其四个属中,数量上Anagrus＞Gonatocerus＞Neurotes＞Mymar;赤眼蜂科数量较少,所占比率小于9%.非综防区化学农药的毒性和残效加重了生境中寄生蜂生存压力,造成群落中多个物种占有优势地位,而稻飞虱主要天敌-缨小蜂的优势被削弱,不如综防区群落中缨小蜂的优势地位突出.     

两种稻虱缨小蜂种群生态的比较

在南京市郊和我国南方稻区,寄生稻飞虱卵的缨小蜂主要是稻虱缨小蜂Anagrus nilaparvatae Pang et wang和拟稻虱缨小蜂A.paranilaprvatae Pang et Wang两个种.这两个种在田间的种群消长,呈明显“此起彼落”的季节性交替.作者以比较生态学方法探讨了产生这一现象的原因.夏季30℃以上高温对稻虱缨小蜂未成熟期的存活和雌虫产卵有明显抑制作用,但拟稻虱缨小蜂具有耐高温能力.稻虱缨小蜂和拟稻虱缨小蜂种群增长的理论最适温度分别为27.41℃和31.87℃,最适温度下的种群内禀增长力以稻虱缨小蜂为高.当供以白背飞虱和褐飞虱卵时,拟稻虱缨小蜂只寄生褐飞虱卵,稻虱缨小蜂对褐飞虱卵也有明显的喜好.两种缨小蜂对褐飞虱卵密度的功能反应均符合Holling Ⅱ型.     

稻虱缨小蜂对褐飞虱和白背飞虱卵的识别机制

研究了室内条件下信息化合物及稻飞虱卵的形态特征在稻虱缨小蜂识别2种卵寄主褐飞虱和白背飞虱中的作用。结果表明,褐飞虱和白背飞虱雌成虫诱导的水稻挥发物对稻虱缨小蜂的引诱作用无显著差异,各自的引诱比例(头数)分别为57.50%(23头)和42.50%(17头)。稻虱缨小蜂对2种飞虱4组材料,完整卵、磨碎卵、带卵叶鞘和若虫为害叶鞘的行为反应,除了在褐飞虱完整卵上的搜索时间极显著地长于在白背飞虱完整卵上的以外,其余的均不存在差异。挥发物捕集结果表明,褐飞虱和白背飞虱雌成虫诱导的水稻挥发物组成相非常一致。上述结果表明水稻挥发物、稻飞虱利它素及飞虱卵的形态特征在稻虱缨小蜂识别褐飞虱和白背飞虱卵中的作用不明显。文中就稻虱缨小蜂识别2种寄主的机制进行了讨论。     

水稻品种和稻虱缨小蜂对褐飞虱协同作用的模拟分析

利用我们先前的试验结果和文献资料,组建了水稻品种－褐飞虱－稻虱缨小蜂３者相互关系的模拟模型．模拟分析表明水稻品种能直接和间接地通过物理或化学特性影响稻虱缨小蜂的寄生作用,其中以影响褐飞虱卵垂直分布型、稻虱缨小蜂的迁入时间、未成熟期历期和怀印量等的水稻品种特性起主要作用．同时,模拟分析还表明中等抗性的水稻品种,配以增强稻虱缨小蜂寄生作用的品种特性,就能有效地控制褐飞虱的危害．文中还就协调水稻品种抗性与天敌协同控制褐飞虱的途径进行了讨论．     

水稻防御信号NO对褐飞虱产卵刺激的响应

植物对昆虫产卵刺激产生的防御反应不仅可以直接抑制卵的发育,还可以为防御下一步若虫/幼虫带来的危害做准备。对褐飞虱产卵处理后水稻植株内一氧化氮(NO)合成的关键酶-硝酸还原酶基因的表达量和NO含量进行测定,对比褐飞虱取食和机械损伤处理,结果显示褐飞虱产卵能够诱导水稻硝酸还原酶基因的表达和NO的生成。处理后12 h,水稻硝酸还原酶基因表达量显著高于取食和和机械损伤处理;12-24 h产卵诱导的NO含量显著高于对照和机械损伤组水稻。褐飞虱产卵诱导水稻启动NO合成关键基因的表达和物质合成表明,与取食危害类似,水稻同样会对褐飞虱产卵刺激产生响应,诱导NO升高,启动相应的植物防御体系。     

Experimental field studies on predation and egg parasitism of rice brown planthopper in Indonesia

• 1 Egg parasitism and general predation are known to be important mortality factors in the population dynamics of rice brown planthopper (BPH) Nilaparvata lugens in tropical Asia, but previous studies have not attempted to quantify and compare them.
• 2 Field experiments in Java, Indonesia, are reported for 1993 and 1994. Plants previously infested with BPH eggs were put out in field cage‐enclosures, which, by means of different size mesh gauze covering, allowed either: (1) free access to all natural enemies, (2) access only to egg parasitoids, or (3) no access to any natural enemies.
• 3 After one BPH generation (30 days), numbers of adults and gravid females were counted for each treatment. In addition, plants were dissected to determine the numbers of eggs laid.
• 4 An additional treatment in which all natural enemies were excluded, but lycosid spiders were added, was used in 1994 experiments in an attempt to assess the effects of predators in the absence of egg parasitoids.
• 5 Numbers of BPH adults and eggs laid were highest when natural enemies were excluded and lowest when they had free access. Mortality due to egg parasitoids in the absence of predators was intermediate and significantly different to the two other treatments.
• 6 The effects of added predators in the absence of egg parasitoids gave variable results, but again clearly demonstrated the significance of egg parasitism in overall BPH mortality.
• 7 The conservation of BPH egg parasitoids should form an important element of any rice pest management programme in tropical Asia.

     

Host plants alter their volatiles to help a solitary egg parasitoid distinguish habitats with parasitized hosts from those without

When attacked by herbivores, plants emit volatiles to attract parasitoids and predators of herbivores. However, our understanding of the effect of plant volatiles on the subsequent behaviour of conspecific parasitoids when herbivores on plants are parasitized is limited. In this study, rice plants were infested with gravid females of the brown planthopper (BPH) Nilaparvata lugens for 24 hr followed by another 24 hr in which the BPH eggs on plants were permitted to be parasitized by their egg parasitoid, Anagrus nilaparvatae; volatiles from rice plants that underwent such treatment were less attractive to subsequent conspecific parasitoids compared to the volatiles from plants infested with gravid BPH females alone. Chemical analysis revealed that levels of JA and JA-Ile as well as of four volatile compounds—linalool, MeSA, α-zingiberene and an unknown compound—from plants infested with BPH and parasitized by wasps were significantly higher than levels of these compounds from BPH-infested plants. Laboratory and field bioassays revealed that one of the four increased chemicals—α-zingiberene—reduced the plant's attractiveness to the parasitoid. These results suggest that host plants can fine-tune their volatiles to help egg parasitoids distinguish host habitats with parasitized hosts from those without.     

Seasonal patterns of egg parasitism and natural biological control of rice brown planthopper in Indonesia

1 Egg mortality is known to be an important factor in brown planthopper (BPH) (Nilaparvata lugens) population dynamics in tropical Asia, but few quantitative data are available on the role of egg parasitoids. 2 Field studies are reported at two sites in Java, Indonesia, over a period of 4 years in both wet and dry seasons, where no chemical pesticides were used. Rice plants previously infested in the laboratory with BPH eggs were exposed to natural parasitism and predation in experimental fields for periods of 5 days. 3 Egg batches were dissected from both experimental and control plants after field exposure at seven fortnightly intervals through the rice growing season and BPH nymphs and adult parasitoids were allowed to emerge. 4 Parasitism by species of Oligosita (Hymenopera, Trichogrammatidae) and Anagrus (Hym., Mymaridae) varied between 18% and 61% in dry, and from 1% to 65% in wet, seasons. There was generally a trend from low to higher rates through wet seasons, contrasting with more uniform higher levels through dry seasons. 5 Reduction in BPH survival as a result of egg parasitism varied between 29% and 91%. Generally parasitism was density independent. 6 It is suggested that lower initial levels of parasitism in dry seasons may be due to the longer fallow period between dry and wet, than between wet and dry, resulting in lower local populations of appropriate natural enemies. 7 Unlike previous studies in Asia, little evidence was found for egg predation as an important mortality factor. 8 The conservation of egg parasitoids should form part of any rice pest management programmes in tropical Asia.     

水稻OsLecRK1基因介导的抗褐飞虱功能分析

褐飞虱Nilaparvata lugens St(a)l是对水稻最具破坏性的害虫之一,OsLecRK1是水稻Bph3基因簇中对褐飞虱抗性贡献最大的基因.本文对RHTd(含Bph3)等材料进行了褐飞虱抗性评价,克隆并构建了OsLecRK1过量表达突变体水稻,利用该突变体分析了OsLecRK1基因对褐飞虱若虫存活率、若虫发育历期等生物学参数的影响.结果 表明,含Bph3基因水稻RHTd对褐飞虱的抗性明显地强于含Bph1基因水稻Mudgo和bph2基因水稻ASD7,RHTd水稻的褐飞虱受害指数仅为Mudgo和ASD7水稻的53.5％和24.1％.过量表达OsLecRK1基因能显著地增加水稻对褐飞虱的驱避性和抗生性,褐飞虱雌成虫偏好于在野生型水稻上产卵;突变体水稻上的褐飞虱若虫存活率显著地降低,仅为野生型水稻上若虫存活率的75.2％ ～81.8％,且若虫发育历期显著地延长,羽化率和初羽化雌成虫体重均显著地降低;此外,褐飞虱在突变体水稻上取食分泌的蜜露量只有野生型上的40.3％ ～ 60.9％,褐飞虱单雌产卵量只为野生型51％ ～61.2％,卵孵化率只有野生型的52.2％～56.7％,均显著地减少.结果 表明,含Bph3基因水稻RHTd对褐飞虱的抗性明显地高于分别含Bph1、bph2的水稻Mudgo和ASD7;水稻Bph3基因座的OsLecRK1单个基因过量表达即可显著增加水稻对褐飞虱的抗性,OsLecRK1协同影响褐飞虱的多个生物学参数降低褐飞虱的适合度.     

Multi-generation effects of Bt rice on Anagrus nilaparvatae, a parasitoid of the nontarget pest Nilapavarta lugens

Little is known about the potential cumulative long-term effects of transgenic crops on nontarget organisms. In the present laboratory study, the potential cumulative effects of transgenic Bacillus thuringiensis (Bt) rice on parasitoids in successive generations were observed for an egg parasitoid, Anagrus nilaparvatae parasitizing eggs of Nilaparvata lugens (St?l) (Hemiptera: Delphacidae) feeding on Bt rice. Enzyme-linked immunosorbent assay test confirmed that Cry1Ab insecticidal protein could be detected in newly eclosed parasitoid adults. However, no significant effect on the fecundity of Anagrus nilaparvatae Pang et Wang (Hymenoptera: Mymaridae) was observed between Bt and non-Bt rice. Developmental times of both genders of A. nilaparvatae parasitizing host eggs laid in Bt (KMD1 and KMD2) rice lines were significantly prolonged from first generation to second generation, but not always prolonged from third generation to 11th generation as compared with the control rice line. Furthermore, the sex ratio of A. nilaparvatae progeny from the first generation to 11th generation in three rice lines was not significantly different. In general, our results suggested that the effect of Bt rice on this parasitoid could be negligible.