双斑恩蚜小蜂的生殖方式及其在烟粉虱体内的发育

首次对双斑恩蚜小蜂Encarsia bimaculata Heraty et Polaszek雌蜂的胚胎发育全过程进行连续观测和数码摄像,明确了双斑恩蚜小蜂的生殖方式是两性产雌,雌蜂为初寄生蜂,孤雌产雄且雄蜂为自复寄生。雌蜂在温度(25±1)℃,相对湿度70%±10%条件下,从卵到成虫的发育历期为(13.1±2.5)d,卵期(1.98±0.38)d,幼虫1龄(0.95±0.33)d,2龄(2.48±0.40)d,3龄(3.46±0.43)d,预蛹(0.95±0.20)d,蛹(4.88±0.80)d。     

烟粉虱生物型对浅黄恩蚜小蜂寄主选择及个体发育的影响

为探讨寄生蜂在Q型烟粉虱Bemisia tabaci替代B型烟粉虱的过程中是否起作用, 我们在实验室条件(温度27±1℃, 光周期16L∶8D, 相对湿度RH 70%～80%)下, 观察了浅黄恩蚜小蜂Encarsia sophia寄生B型和Q型烟粉虱若虫的行为, 研究了浅黄恩蚜小蜂对B型和Q型烟粉虱若虫的选择性、 烟粉虱生物型对浅黄恩蚜小蜂取食数量及个体发育的影响。结果发现, 浅黄恩蚜小蜂体外检测时间在B型和Q型烟粉虱若虫间差异不显著, 而寄生Q型烟粉虱若虫时的体内检测和产卵时间(190.2±14.6 s）显著高于寄生B型时所用时间(140.0±7.5 s)。在非选择条件下, 浅黄恩蚜小蜂寄生B型烟粉虱若虫的数量(8.1±0.5头)及总产卵量（9.3±0.6粒）显著高于仅提供Q型烟粉虱的寄生数量(6.3±0.5头)及总产卵量(7.0±0.6粒); 而被寄生若虫单头着卵量在处理间差异不显著。在选择性条件下, 该蜂寄生B型烟粉虱若虫量(3.1±0.4头)、总产卵量(3.8±0.5粒)及被寄生若虫单头着卵量(1.2±0.1粒)都显著高于寄生Q型烟粉虱时的情况(1.8±0.3头、1.8±0.4粒、0.7±0.1粒)。被寄生蜂取食的B型与Q型烟粉虱数量间差异不显著, 但对于同一生物型而言, 交配过的雌蜂能够取食更多的烟粉虱若虫。以B型烟粉虱为寄主时, 浅黄恩蚜小蜂雌蜂卵-黑蛹(7.2±0.1 d)、黑蛹-羽化(5.2±0.1 d)的发育时间与以Q型烟粉虱若虫为寄主时的相应发育时间(7.3±0.1 d, 5.6±0.1 d)间无显著性差异。以B型烟粉虱为寄主时寄生蜂的羽化率（73.55%±1.42%）与以Q型烟粉虱为寄主时的羽化率（68.42%±13.01%）间差异不显著。这些结果表明, 虽然浅黄恩蚜小蜂发育时间、 羽化率在烟粉虱2种生物型间无显著差异, 但该小蜂倾向于B型烟粉虱若虫作为寄主, 而且, 以B型烟粉虱若虫为寄主时, 小蜂的产卵量和寄生若虫数量均增加。但田间浅黄恩蚜小蜂的存在是否有助于Q型烟粉虱成为B型和Q型混合种群的优势种群, 还需进一步研究。     

两种蚜小蜂对烟粉虱寄主的产卵选择性(英文)

双斑恩蚜小蜂和桨角蚜小蜂是华南地区烟粉虱的两种优势种寄生蜂。本文研究了两种寄生蜂对不同龄期烟粉虱寄主的产卵选择特性。结果表明:两种寄生蜂均可寄生烟粉虱的1~4龄若虫。当只有1个龄期的烟粉虱若虫存在时,双斑恩蚜小蜂更多地寄生3龄和4龄若虫,较少寄生1龄和2龄若虫;而桨角蚜小蜂则更多地寄生3龄和2龄若虫,较少寄生1龄和4龄若虫。在4个龄期若虫同时存在时,双斑恩蚜小蜂会明显增加对3龄和4龄若虫的产卵寄生,降低对1龄和2龄若虫的寄生;而桨角蚜小蜂则增加对2龄和3龄若虫的寄生,减少对1龄和4龄若虫的寄生。寄主植物的差异不影响这二种蚜小蜂对各龄期烟粉虱若虫的产卵选择倾向。结果提示,烟粉虱若虫3龄和4龄是双斑恩蚜小蜂最适宜的寄主,而桨角蚜小蜂最适宜的寄主是烟粉虱2龄和3龄若虫。     

两种蚜小蜂对烟粉虱寄主的产卵选择性（英文）

双斑恩蚜小蜂和桨角蚜小蜂是华南地区烟粉虱的两种优势种寄生蜂。本文研究了两种寄生蜂对不同龄期烟粉虱寄主的产卵选择特性。结果表明: 两种寄生蜂均可寄生烟粉虱的1～4龄若虫。当只有1个龄期的烟粉虱若虫存在时,双斑恩蚜小蜂更多地寄生3龄和4龄若虫,较少寄生1龄和2龄若虫;而桨角蚜小蜂则更多地寄生3龄和2龄若虫,较少寄生1龄和4龄若虫。在4个龄期若虫同时存在时,双斑恩蚜小蜂会明显增加对3龄和4龄若虫的产卵寄生,降低对1龄和2龄若虫的寄生;而桨角蚜小蜂则增加对2龄和3龄若虫的寄生,减少对1龄和4龄若虫的寄生。寄主植物的差异不影响这二种蚜小蜂对各龄期烟粉虱若虫的产卵选择倾向。结果提示,烟粉虱若虫3龄和4龄是双斑恩蚜小蜂最适宜的寄主,而桨角蚜小蜂最适宜的寄主是烟粉虱2龄和3龄若虫。     

双斑恩蚜小蜂形态学特征、生活习性及其寄生行为

双斑恩蚜小蜂EncarsiabimaculataHeratyetPolaszek是烟粉虱Bemisiatabaci(Gennadius)的主要寄生性天敌之一。作者对双斑恩蚜小蜂的形态特征进行了描述。在实验室条件下,对双斑恩蚜小蜂的生活习性、寄生行为进行了观察。双斑恩蚜小蜂成蜂26℃时平均寿命约为7d,每雌产卵量273粒,雌蜂比例占据绝对优势,雌雄性比约为8∶1。双斑恩蚜小蜂的寄生过程大致分为寄主定位、寄主检查、穿刺、产卵、清扫、梳理和休憩等几个阶段。     

寄主植物对双斑恩蚜小蜂的发育、存活和繁殖的影响

研究了茄子和扶桑两种不同寄主植物对烟粉虱寄生性天敌双斑恩蚜小蜂Encarsia bimaculata发育、存活和繁殖等特性的影响。在26±0.5℃的条件下,在扶桑上,双斑恩蚜小蜂卵至成虫的发育历期为13.6天,2龄幼虫至成虫的存活率为93.2%;而在茄子上双斑恩蚜小蜂卵至成虫的发育历期和2龄幼虫至成虫的存活率分别为12.1天和91.1％。扶桑上双斑恩蚜小蜂雌性成虫的平均寿命为8.0天,平均单雌产卵量为35.9粒;而在茄子上雌性成虫的平均寿命为6.6天,平均单雌产卵量为27.6粒。双斑恩蚜小蜂在扶桑和茄子植物上的种群内禀增长率分别为0.2081和0.892。两种不同寄主植物对双斑恩蚜小蜂在若虫发育历期和存活率、成虫寿命和平均产卵量以及内禀增长率等方面均存在着显著差异。研究结果表明,寄主植物对双斑恩蚜小蜂的发育、存活和繁殖有较大的影响。     

海氏桨角蚜小蜂对两种生物型烟粉虱的功能反应研究

本文报道海氏桨角蚜小蜂Erelmocerus hayati在室内对不同寄主密度下的B型和Q型烟粉虱Bemisiatabaei寄生和取食情况,并比较了该蜂对两种生物型烟粉虱功能反应的差异。结果表明,海氏桨角蚜小蜂对两种生物型烟粉虱的寄生率和致死率可分别达到60％和70％以上,平均每日最大致死量可达40头烟粉虱若虫。该蜂对两种生物型烟粉虱的功能反应曲线符合Holling Ⅱ型,随寄主密度的增加对烟粉虱若虫的寄生和致死数量均增加直至达到每日最大致死数量,而寄生率和致死率则随寄主密度的增加而显著下降。该蜂对两种生物型烟粉虱的功能反应没有显著的差异。     

双斑恩蚜小蜂寄生对烟粉虱体内保幼激素和20-羟基蜕皮酮含量的影响

用反相高效液相色谱法（RP-HPLC）测定了烟粉虱Bemisia tabaci体内保幼激素和20-羟基蜕皮酮的滴度。结果显示,被双斑恩蚜小蜂Encarsia bimaculata寄生的烟粉虱高龄若虫体内的保幼激素滴度显著高于（P<0.05）对照即未被寄生的高龄若虫,20-羟基蜕皮酮（20-E）滴度显著低于（P<0.05）对照,与未被寄生的低龄若虫滴度差异不显著,说明双斑恩蚜小蜂寄生后可以将烟粉虱高龄若虫的激素含量保持在低龄若虫的水平,从而调节烟粉虱高龄若虫的生长发育。烟粉虱伪蛹和成虫与对照体内保幼激素含量,烟粉虱伪蛹与对照之间20-E含量差异均不显著（P>0.05）。     

蚜小蜂和粉虱座壳孢对烟粉虱的控制作用研究

研究了烟粉虱两种寄生性天敌桨角蚜小蜂(Eretmocerus sp．)和粉虱座壳孢(Aschersonia aley-rodis)单独使用和联合使用时对烟粉虱种群的控制作用。结果表明,在单独进行控制时,在一个世代内按5×10^6个孢子·ml^-1喷施粉虱座壳孢2次,对烟粉虱种群的控制作用达95．74％,按每株植株3头雌蜂的密度释放桨角蚜小蜂2次,对烟粉虱种群的控制作用达57.58％。在两者联合控制时,一个世代内喷施粉虱座壳孢2次,再释放桨角蚜小蜂1次或2次,对烟粉虱种群的控制作用达97．02％～97．91％,烟粉虱种群增长趋势指数低于1,种群数量逐渐下降,联合使用时,桨角蚜小蜂和粉虱座壳孢间无消极影响。     

海氏桨角蚜小蜂对不同龄期“Q”烟粉虱的取食和寄生反应

【背景】近年来＂Q＂烟粉虱在我国快速扩张,已成为农业生产上的一种重要入侵害虫。由于化学农药的大量使用,＂Q＂烟粉虱已对多种农药产生高抗药性,保护和利用天敌昆虫对其进行控制具有重要意义。【方法】本文在室内研究了近年引入我国的海氏桨角蚜小蜂对不同龄期＂Q＂烟粉虱若虫的取食和寄生能力。【结果】各龄期的＂Q＂烟粉虱若虫均可被海氏桨角蚜小蜂取食和寄生。在48h内,寄生蜂取食1、2、3、4龄烟粉虱若虫的数量分别为10.7、6.4、6.7、5.0头,呈现随龄期增大取食数量下降的趋势;海氏桨角蚜小蜂对不同龄期烟粉虱若虫的寄生能力存在明显差异,其更偏好寄生2、3龄若虫（25.4和27.5头）,其次是1龄若虫（22.1头）,而寄生4龄粉虱的数量最低（16.5头）。【结论与意义】寄主龄期对海氏桨角蚜小蜂的取食和寄生能力具有显著影响。综合来看,该寄生蜂表现出对＂Q＂烟粉虱较好的生物防治潜能,是防治烟粉虱的理想寄生性天敌昆虫。     

Effect of Bemisia tabaci honeydew and its carbohydrates on search time and parasitization of Encarsia bimaculata

Abstract:  The search time of Encarsia bimaculata Heraty et Polaszek was examined and recorded by using filter paper discs in Petri dish arenas impregnated with Bemisia tabaci (Gennadius) honeydew or its component carbohydrates. Our data show that E. bimaculata used honeydew as a contact kairomone to locate its host. Females responded quantitatively to the honeydew and the search time in the treated patches increased. This increase was concentration-dependent with regard to the amount of honeydew applied, but it levelled off 0.05 g/ml onwards. The response of E. bimaculata to honeydew decreased with increasing time after application and was significantly reduced 8 days after treatment. The parasitoid females were also arrested in patches treated with glucose, fructose, trehalulose and trehalose; trehalose elicited the highest response in the parasitoids. However, sucrose and low concentrations of melezitose did not elicit a significant effect. Glucose, sucrose, fructose, trehalose and trehalulose increased the longevity of the parasitoid females by a factor of 8.4, 8.1, 6.3, 6.1 and 4.2, respectively. Melezitose and 0.15 g/ml natural honeydew, however, had no effect on parasitoid lifespan. The effects of aqueous spray of honeydew sugars on egg to adult survivorship and parasitization of B. tabaci by E. bimaculata significantly differed when compared with controls only in cases where mixtures of glucose + fructose and trehalose and fructose + trehalose were applied.     

Delayed development of the whitefly (Bemisia tabaci) and increased parasitism by Encarsia bimaculata in response to sublethal doses of piperonyl butoxide

Abstract Effects of sublethal piperonyl butoxide (PB) on parasitization of Bemisia tabaci (Gennadius ) (Hemiptera: Aleyrodidae) by Encarsia bimaculata Heraty et Polaszek (Hymenoptera: Aphelinidae) were evaluated both in cage and greenhouse experiments. When first, second and third instar B. tabaci nymphs were treated with PB, all but the first instar were significantly prolonged. Data indicated that sublethal PB could improve E. bimaculata parasitism rates without influencing parasitoid eclosion rates. Prolonged development increased rates of parasitism by E. bimaculata, from 17.6% to 24.7% in cages, presumably by increasing the duration of host exposure. Sublethal PB combined with E. bimaculata as an integrated approach to control B. tabaci was evaluated using life table parameters under greenhouse conditions. Indices of population trend (I) calculated from life tables were estimated at 4.6 for B. tabaci exposed to PB and parasitoids compared to 14.1 with parasitoids alone and 23.5 in untreated controls. The results showed that after PB was sprayed and parasitoids introduced, development of B. tabaci was delayed and the peak of each stage was postponed. The older nymphal stage had highest mortality, primarily due to mortality caused by parasitism by E. bimaculata.     

Suitability of Bemisia tabaci (Hemiptera: Aleyrodidae) instars for the parasitization by Encarsia bimaculata and Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae) on glabrous and hirsute host plants

The host instar preferences of Encarsia bimaculata and Eretmocerus sp. nr. furuhashii parasitizing Bemisia tabaci and their development on four host plants, collard, eggplant, cucumber and tomato, were studied in the laboratory. Both of the parasitoids accepted all nymphal stages of B. tabaci, but E. bimaculata preferred third and fourth instars while Er. sp. nr. furuhashii preferred second and third instars under both choice and no choice conditions. Regardless of host stage parasitized, adults of parasitoids emerged only from fourth instars. When given the simultaneous choice of all instars, E. bimaculata reduced parasitization of first and second instars (3.73 and 4.76%, respectively) while increasing parasitization of third and fourth instars (5.44 and 6.93%, respectively), in contrast Er. sp. nr. furuhashii increased its parasitization of second and third instar nymphs (1.27 and 3.17%, respectively) and decreased that of first and fourth instars (7.0 and 3.06%, respectively). Host plants did not significantly influence instar preference for either parasitoid. Developmental periods of both the parasitoids from egg to adult emergence were longest when first instars were parasitized and shortest when fourth instars were selected. Parasitoid developmental time was generally shorter on glabrous plants than on hirsute plants.     

Interspecific interference competition between Encarsia formosa and Encarsia sophia (Hymenoptera: Aphelinidae) in parasitizing Bemisia tabaci (Hemiptera: Aleyrodidae) on five tomato varieties

Abstract Interspecific competition between Encarsia formosa and Encarsia sophia, two major parasitoids of Bemisia tabaci, and the influence of five tomato varieties on competition outcome were investigated under laboratory conditions. E. formosa parasitized more B. tabaci than E. sophia when in single wasp assays on any of the tomato varieties investigated. When B. tabaci nymphs were exposed to both wasp species (either simultaneously or sequentially), the number of B. tabaci nymphs parasitized by either wasp species was significantly decreased compared to the sole access condition. Total mortality of B. tabaci was increased when B. tabaci nymphs were exposed to both wasp species compared to only one wasp species. Thus competition between E. formosa and E. sophia apparently reduced parasitoid offspring numbers, but not the efficiency of biological control. In fact, control efficiency was enhanced in some cases, particularly on tomato variety Huangtuoyuan (HTY). When wasps were allowed sequential access to hosts, interference occurred through host feeding by the second wasp, especially if it was E. sophia. The effect of different tomato varieties was not significant.