白蜡窄吉丁幼虫及其天敌在空间格局上的关系

调查了白蜡窄吉丁幼虫与其寄生性天敌白蜡吉丁柄腹茧蜂和捕食性天敌啄木鸟啄食白蜡窄吉丁的啄痕在空间格局上的规律.结果表明,在林间水平方向上,白蜡窄吉丁幼虫呈聚集分布,白蜡吉丁柄腹茧蜂和啄木鸟的啄痕也表现为聚集分布;在垂直方向上,白蜡窄吉丁幼虫分布于地面至3.37m以下的树干,主要集中于1.0m左右的主干,天敌也集中在此范围内活动.     

白蜡吉丁柄腹茧蜂的寄生和繁殖生物学

白蜡吉丁柄腹茧蜂Spathius agrili Yang是我国天津地区寄生白蜡窄吉丁幼虫的一种重要天敌。本研究通过林间调查并结合室内观察,测定了该寄生蜂在不同营养条件下的存活时间和不同时期的产卵量,调查了不同寄主大小对寄生蜂后代生长发育的影响,以及寄生蜂对不同深度树皮下的寄主利用情况。结果表明：不同营养条件下白蜡吉丁柄腹茧蜂的存活时间差异很大,补充20％蜂蜜水的成蜂存活时间明显延长,最长可达3个月。相同条件下雌蜂的存活时间比雄蜂略长。在补充营养的条件下,茧蜂的产卵时间最长可达8周,产卵的高蜂在羽化后第2周前后,平均每雌每周产卵量在整个产卵期内基本保持在8～12粒上下,没有大的波动。茧蜂低龄幼虫也可能分泌毒素主动攻击寄主,提高了寄生蜂后代的生存能力。寄主个体大,营养量也大,寄生其上的茧蜂幼虫成功完成发育的数量随之增加,表明寄主营养资源的多少直接影响到寄生蜂后代的生长发育和存活。白蜡吉丁柄腹茧蜂对1～6.5 mm树皮深度范围内的适龄寄主幼虫均能够寄生利用,约92％的被寄生白蜡窄吉丁幼虫个体分布于1～4 mm深度的树皮下,在3 mm厚的树皮下分布的数量最多。茧蜂数量与树皮深度大致上呈抛物线关系,理论上在树皮深度为3.97 mm处茧蜂分布数量最多。     

温度对白蜡吉丁柄腹茧蜂发育和繁殖的影响

为了提高白蜡窄吉丁Agrilus planipennis的重要天敌——白蜡吉丁柄腹茧蜂Spathius agrili Yang的繁育效率, 本研究调查了不同温度（22, 24, 26, 28, 30和32℃）对该蜂生长发育及繁殖的影响。结果表明, 在22~32℃范围内, 白蜡吉丁柄腹茧蜂的卵、茧蛹及世代发育速率均随着温度的升高而加快, 而幼虫的发育速率在26℃时最快. 卵、幼虫、茧蛹和世代的发育起点温度分别为14.34, 16.89, 14.16和13.84℃, 有效积温分别为24.59, 61.16, 166.27和276.80日·度。温度对白蜡吉丁柄腹茧蜂的寄生率、寄生成功率、产卵量、子代蜂数量和性比都有不同程度的影响。据此提出适于人工繁育白蜡吉丁柄腹茧蜂的温度范围为26~28℃。     

白蜡吉丁肿腿蜂的生物学和生态学特性及繁殖技术研究

采用室内测定并结合林间实地调查的方法,研究了新发现的寄生于蛀干害虫白蜡窄吉丁的外寄生蜂——白蜡吉丁肿腿蜂Sclerodermus pupariae Yang et Yao的生物学特性及其人工繁殖技术。结果表明,白蜡吉丁肿腿蜂外寄生于白蜡窄吉丁的幼虫和蛹及预蛹,是自然控制该害虫的一种重要寄生蜂,自然寄生率为13.9%左右。该蜂在天津1年发生5代,世代重叠明显,寿命长。白蜡吉丁肿腿蜂的卵、幼虫、茧蛹期和全世代的发育起点温度分别为（16.89±0.79）℃,（17.03±1.42）℃,（16.90±1.68）℃和（15.31±0.47）℃。有效积温分别为（33.82±4.13）日·度、（49.11±7.93）日·度、（128.88±27.87）日·度和（277.00±14.15）日·度。雌性成蜂易于低温保存,对寄主有较强的搜索力和攻击力。繁蜂寄主容易大量获得,是生物防治白蜡窄吉丁的重要理想天敌之一。     

栗山天牛幼虫天敌白蜡吉丁肿腿蜂的转主寄主研究

在利用白蜡吉丁肿腿蜂Sclerodermus pupariae防治世代周期长、 发育整齐的害虫栗山天牛Massicus raddei中, 我们发现该天敌只在寄主1-3龄幼虫时具有良好的寄生效果, 而对3龄以上的中老龄幼虫基本不寄生。为了了解释放白蜡吉丁肿腿蜂后其种群能否在栎树林间延续下去, 达到持续控制靶标害虫的效果, 我们调查了其在栎树林间的转主寄主。结果表明： 白蜡吉丁肿腿蜂除了寄生栗山天牛外, 还能寄生双簇天牛Moechotypa diphysis、 四点象天牛Mesosa myops和栎块斑吉丁Lamprodila virgata幼虫。白蜡吉丁肿腿蜂寄生不同转主寄主幼虫的成功率差异显著, 对栎块斑吉丁和双簇天牛幼虫的寄生率最高, 分别为76.67%和73.33%。寄生上述4种寄主时, 其雌蜂在不同寄主上的产卵前期、 产卵量及第2代雌蜂出蜂量、 出蜂率、 体长和寿命等差异不显著, 只有幼虫期和蛹期历期及第2代雌蜂有翅率和雌雄性比略有差异。室内模拟林间寄生试验表明, 白蜡吉丁肿腿蜂对双簇天牛和四点象天牛幼虫的寄生率较高。对双簇天牛和四点象天牛野外生活史研究发现, 这2种天牛幼虫在白蜡吉丁肿腿蜂不适宜寄生的栗山天牛中老龄幼虫期、 蛹期和成虫期均大量存在, 表明双簇天牛和四点象天牛是白蜡吉丁肿腿蜂在栎树林中的主要转主寄主。本研究说明, 在利用白蜡吉丁肿腿蜂生物防治栗山天牛中, 白蜡吉丁肿腿蜂在林间寄生栗山天牛的1-3龄幼虫后, 可转移寄生双簇天牛等转主寄主, 以延续其种群, 待下一代栗山天牛幼龄幼虫出现时再转移寄生栗山天牛, 达到持续控制栗山天牛的防治效果。     

六盘山翠金小蜂生物学特性的研究

六盘山翠金小蜂Tritneptis sp.是华北落叶松人工林主要食叶害虫落叶松红腹叶蜂Pristiphora erichsonii Hartig茧期的体外复寄生性天敌。对该蜂的生物学特性研究表明,该蜂在宁夏六盘山1年2代,以幼虫在寄主茧内越冬,翌年4月中旬开始活动取食,5月中旬开始化蛹,成蜂从6月中旬开始羽化,每头虫茧平均出蜂6.14头,雌雄比1.79∶1,雌蜂6月下旬开始产卵,一只雌蜂一生可在12.2头寄主虫茧上产卵,第1代寄生蜂幼虫7月上旬开始孵化并吸食寄主营养发育,7月下旬开始化蛹,8月上旬开始羽化并交尾、产卵寄生。该蜂体型较大,对寄主跟随性强,无重寄生天敌,自然寄生率7.3%～33.6%,是一种优良天敌寄生蜂。     

白蜡窄吉丁幼虫及其天敌的种群空间生态位研究

【目的】为了明确白蜡窄吉丁Agrilus planipennis Fairmaire幼虫及其天敌在寄主树上的分布规律和相互关系。【方法】对天津和北京两个地区绒毛白蜡Fraxinus velutina和辽宁地区水曲柳F mandshurica上白蜡窄吉丁幼虫及其天敌的种群生态位进行研究。【结果】白蜡窄吉丁幼虫及其天敌的数量均随着寄主树干高度的增加而逐渐减少,但在不同寄主树种上的分布范围不同。绒毛白蜡上的分布范围较广,而在水曲柳主干上的分布高度相对较低。天敌对白蜡窄吉丁幼虫在空间资源的利用上也存在差异。在天津地区,白蜡吉丁柄腹茧蜂Spathius agrili Yang(膜翅目:茧蜂科)和啄木鸟(■形目:啄木鸟科)的跟随作用最强,且白蜡吉丁柄腹茧蜂与啄木鸟之间对空间资源的利用存在激烈竞争。在北京地区,啄木鸟的跟随作用最强,病原微生物、扁胫旋小蜂、白蜡吉丁柄腹茧蜂之间对空间和营养资源利用的竞争较激烈。而在辽宁地区,白蜡窄吉丁幼虫和天敌的分布范围较窄,各类天敌在空间上对寄主幼虫的跟随作用不是很明显,但不同天敌种类之间对空间和营养资源的利用也存在竞争。【结论】研究结果为白蜡窄吉丁的综合治理和天敌资源的保护利用提供了理论依据。     

枣园桃蛀果蛾寄生蜂种类及其与寄主的关系

桃蛀果蛾(Carposina sasakii Matsumura)是我国十分重要的果实性害虫,其中枣受害最严重,因其幼虫在果实内蛀食危害、高度隐蔽性的生活而较难防治。寻找有效天敌,开展生物防治成为必然。2009年与2010年研究调查了我国大枣部分产区陕西、山西、河南与宁夏枣园桃蛀果蛾寄生性天敌,共发现了3种寄生蜂,即中华齿腿姬蜂(Pristomerus chinensis Ashmead)、章氏小甲腹茧蜂(Chelonus(Microchelonus)zhangi Zhang)和金小蜂(Pteromalidae),3种寄生蜂均从桃蛀果蛾的茧中羽化而出,其中中华齿腿姬蜂和章氏小甲腹茧蜂为优势天敌,但它们表现出十分明显的地域性分布。同时,对中华齿腿姬蜂和章氏小甲腹茧蜂羽化、寄生率以及与寄主之间的关系进行了初步研究,结果表明,中华齿腿姬蜂越冬代成虫出蛰活动始于6月中旬,越冬代寄生率较低,第1代成虫羽化在8月下旬至9月上旬,这代寄生蜂具有较高的寄生率,可达25%;章氏小甲腹茧蜂第1代成虫羽化集中在8月中下旬和9月上旬,由于在2009年与2010年对样地进行不施用杀虫剂的管理,该天敌在2010年自然寄生率显著提高,最高时可达64.52%。因此,科学管理,合理保护与利用当地天敌成为实现该害虫生物防治的关键。     

宽额螯蜂的幼期形态及生物学特性研究

宽额螯蜂Dryinus latus Olmi在山东商河寄生恶性席瓢蜡蝉Sivaloka damnosus Chouet Lu若虫,具有捕食和寄生的双重控制作用。首次明确该蜂寄主,记述其幼期形态特征、生活史、生活习性。在山东商河1年发生2代,以4龄老熟幼虫在茧内越冬。翌年4月下旬至5月上旬为化蛹盛期,5月中旬越冬代成虫开始出现,捕捉寄主若虫补充营养。成虫主要产卵于恶性席瓢蜡蝉3～5龄若虫前后翅芽下紧贴体背的淡绿色组织上。第1代卵历期平均78.1h,幼虫孵化至脱囊平均历时209.5h,产卵至脱囊平均历时280.0h,蛹期平均386.4h。幼虫作茧于枝条、叶片或地面枯叶上,茧外缀有枝条表皮或叶片碎屑。7月下旬至8月上旬出现第1代成虫,第2代幼虫8月上旬开始脱囊结茧越冬。野外寄生率27.8%～45.7%,控制作用显著。     

茴香薄翅野螟生物学的研究

茴香薄翅野螟是黑龙江省油菜和十字花科蔬菜的一种害虫,幼虫蛀食果荚、籽粒。1年2代,以幼虫在土中结茧越冬。第二年5月中下旬开始化蛹,6月羽化。6月中旬至7月上旬是第一代幼虫危害期,第二代幼虫发生于8月。幼虫有吐丝结网习性,成虫羽化当天即可交配产卵,卵产在嫩角果或柄上。成虫有趋光性,寿命4—16天。     

Notes on the biology and ecology of the parasitoids of the poplar clearwing moth, Paranthrene tabaniformis (Rott.) (Lep., Sesiidae) in Bulgaria. II. Eriborus terebrans (Gravenhorst, 1826) (Hym., Ichneumonidae)

The biology and ecology of Eriborus terebrans (Grav.), a parasitoid of the poplar clearwing moth, Paranthrene tabaniformis (Rott.), were studied during the period 1987–98. One-year-old poplar ( Populus spp.) shoots infested with P. tabaniformis larvae were collected from poplar seedlings at 11 localities in Bulgaria and examined in both field and laboratory conditions. Eriborus terebrans was recorded in seven localities as a solitary internal larval parasitoid of P. tabaniformis which developed two generations in early and mid-stage host larvae. Eriborus terebrans overwintered as a larva in P. tabaniformis overwintering larvae. In the field adult parasitoids of the overwintering generation appeared between late April/early May, and June or July. The peak activity of E. terebrans adults only coincided with the beginning of host emergence, which resulted in low levels of parasitism, being no more than 6.2%. Parasitoid adults of the summer generation appeared in late June–mid August. In this period enough larvae of the host were suitable for attacking and parasitism reached 24.4–39% in some cases. The average mortality of P. tabaniformis overwintering larvae caused by this parasitoid in Bulgaria during the period of the study was 4.7%. A significant part of the parasitized P. tabaniformis larvae constructed tunnel structures of frass and silk threads over the external openings of the galleries. It is possible that these structures protect the parasitoid cocoons from natural enemies – hyperparasitoids and predators.     

Factors affecting growth in the koinobiont endoparasitoid Venturia canescens in the flour moth Ephestia kuehniella

With resistance of insect pests to synthetic pesticides on the increase, the role of parasitoid wasps as biological control agents is expanding in pest and resistance management strategies. One of the predictors of reproductive success of endoparasitoids is the relative size of the wasp at host emergence. While in idiobiont parasitoids, where the host stops feeding after parasitism, the wasp size is determined by the host size at the time of parasitism; the size of koinobiont wasps, where the host continues to feed after parasitism, is dependent on additional factors. Here we show that the host mass and temperature are important factors that determine survival and development of the koinobiont endoparasitoid Venturia canescens in late instar larvae of the flour moth Ephestia kuehniella.     

Lydella thompsoni Herting (Dipt., Tachinidae), a parasitoid of the European corn borer, Ostrinia nubilalis Hbn. (Lep., Pyralidae) in Slovakia, Czech Republic and south-western Poland

This paper shows that, within Central Europe, parasitism of the European corn borer (ECB) by the tachinid parasitoid, Lydella thompsoni (LT) increased from 0.47 to 1.49% in south-western Poland (51°03'N), to 4.31–21.95% in eastern Slovakia (48°20'N). The synchrony between the parasitoid LT and its primary host, the ECB, was studied in Central Europe under conditions where the host is univoltine, but the parasitoid is bivoltine. A cumulated total of more than 400 LT was field-collected from overwintering ECB larvae. The parasitoid hibernated as larva inside the host. Pupation started in the second half of the following March and 50% of pupation was surpassed in the first half of April. The first parasitoid adults emerged at the end of April and the majority at the beginning of May. Development threshold temperatures for 50% pupation was determined to be 2.7°C, and for 50% adult emergence 5.0°C; the respective thermal constants were 178.8–179.8 and 237.7–251.8 Celsius degree-days. Emerged adults did not parasitize overwintered ECB larvae in spring, hence there must be an alternate host for the first generation of LT in areas of univoltine life cycle of the ECB. Parasitization of the ECB larvae by LT continued until the end of July. The first parasitoid adults from this second generation emerged in the second half of August. By the end of the season, nearly one-third of LT adults had emerged. The rest of this generation apparently overwintered in the larval stage.     

Does superparasitism improve host suitability for parasitoid development? A case study in the Microplitis rufiventris-Spodoptera littoralis system

Superparasitism refers to the oviposition behavior of parasitoid females who lay their eggs in an already parasitized host. Recent studies have shown that allocation of additional eggs to an already parasitized host may be beneficial under certain conditions. In the present work, mortality of Microplitis rufiventris wasps was significantly influenced by both host instar of Spodoptera littoralis larvae at parasitism and level of parasitism. In single parasitization, all host instars (first through sixth) were not equally suitable. Percentage of emergence success of wasp larvae was very high in parasitized first through third (highly suitable hosts), fell to 60% in the fourth instar (moderate suitable) and sharply decreased in the penultimate (5th) instars (marginally suitable). Singly parasitized sixth (last) instar hosts produced no wasp larvae (entirely unsuitable), pupated and eclosed to apparently normal adult moths. The scenario was different under superparasitism, whereas supernumerary individuals in the highly suitable hosts were almost always killed as first instars, superparasitization in unsuitable hosts (4th through 6th) had significant increase in number of emergence success of wasp larvae. Also, significantly greater number of parasitoid larvae successfully developed in unsuitable hosts containing three wasp eggs than counterparts containing two wasp eggs. Moreover, the development of surplus wasp larvae was siblicidal in earlier instars and nonsiblicidal gregarious one in the penultimate and last “sixth” instars. It is suggested that the optimal way for M. rufiventris to deal with high quality hosts (early instars) is to lay a single egg, while the optimal way to deal with low quality hosts (late instars) might be to superparasitize these hosts.     

Developmental interaction between suboptimal instars of Spodoptera littoralis (Lepidoptera:Noctuidae) and its parasitoid Microplitis rufiventris (Hymenoptera:Braconidae)

Relative effects of parasitism by Microplitis rufiventris on the development of the third instar Spodoptera littoralis (preferable, optimal host) with the development of penultimate (5th) and last (6th) instars (suboptimal hosts) were investigated. Newly molted 6th instar hosts were more acceptable for parasitization by the wasp female than older hosts. In singly parasitized 3rd instar hosts, 82.0 +/- 3.9% of the parasitoid eggs developed to full-grown instar wasp larvae. However, parasitoid eggs deposited singly in 73.9 +/- 3.3% of 5th and 100% of 6th instar hosts failed to develop. Superparasitization in the 3rd instar hosts reduced the production of pseudoparasitized larvae and, conversely, all parasitized hosts yielded viable parasitoid offspring. In suboptimal hosts, the development interaction between the parasitoid and its host larvae was highly influenced by the age of hosts at parasitism, load of deposited eggs, and other parasitoid factors. The latter factors, e.g., mainly calyx fluid particles, might be involved in establishing parasitoid eggs in the suboptimal hosts. In the last two host instars, superparasitization significantly increased the number of parasitoid larvae successfully reaching their final instar. Variation in host quality, e.g., physiological status, might be attributed, in part, to the partial breakdown of the solitary habit observed in the earlier instars. More parasitoid eggs developed to mature parasitoid larvae in hosts superparasitized as 6th instar than parasitoid eggs laid in 5th instar hosts. Superparasitization significantly lengthened the developmental period of 5th and 6th host instars and inhibited their development to the pupal stage. Studying parasitoid development in suboptimal instars of its habitual host provided physiological insight, as shown here. The results may have implication for biological control and in vitro mass rearing programs with solitary parasitoids.     

Effects of learning experience on behaviour of the generalist parasitoid Sclerodermus pupariae to novel hosts

Massicus raddei Blessig (Coleoptera: Cerambycidae), also referred to as the oak long‐horned beetle (OLB), is a non‐natural host for the generalist parasitoid Sclerodermus pupariae Yang et Yao (Hymenoptera: Bethylidae). To determine whether this generalist parasitoid might be a suitable agent for the control of OLB, the adaptive learning experience of adult female parasitoids to OLB larvae was investigated in the laboratory. A Y‐tube olfactometer bioassay was used to examine the effects of adaptive learning experience on the foraging ability of parasitoids for OLB larvae. The results indicated that parasitoids were significantly attracted by the volatiles of ash bark, Fraxinus velutina, with emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) larvae and larval frass, after exposure to ash bark mixed with EAB larval frass (learning condition A). In contrast, after exposure to oak bark, Quercus liaotungensis, mixed with OLB larval frass (learning condition C), parasitoids showed significant preference for the volatiles of oak bark with OLB larvae and larval frass. On the basis of the results of no‐choice tests, we found that parasitoids exposed to learning condition C had greater paralysis efficiency and higher OLB larvae parasitism rates than those exposed to learning condition A or no experience. Furthermore, parasitoids fed on OLB larvae in learning condition C had significantly greater paralysis efficiency and higher OLB larvae parasitism rates than other parasitoids tested. Parasitoids fed on EAB larvae in learning condition A had the lowest paralysis efficiency and OLB larvae parasitism rates among the parasitoids tested. These findings suggested that adaptive learning significantly enhanced the ability of a generalist parasitoid to utilize a novel host. This may provide a new approach to controlling non‐natural hosts using generalist parasitoids.     

Susceptibility of two hymenopteran parasitoids of Agrilus planipennis (Coleoptera: Buprestidae) to the entomopathogenic fungus Beauveria bassiana (Ascomycota: Hypocreales)

Emerald ash borer (EAB), Agrilus planipennis Fairmaire, native to Asia, is killing ash trees (Fraxinus spp.) across 15 states and southeastern Canada. Integrated pest management using biological control is the only viable long-term approach for controlling the spread of EAB outside of host resistance. Three hymenopteran parasitoids, Spathius agrili Yang, Tetrastichus planipennisi Yang, and Oobius agrili Zhang and Huang were discovered attacking EAB in China and were approved for release in the United States in 2007. The objective of this study was to assess susceptibility of the larval parasitoid species S. agrili and T. planipennisi, relative to that of EAB, to Beauveria bassiana, an entomopathogenic fungus that infects and kills EAB adults when sprayed on ash bark or foliage. Adult EAB and parasitoids were exposed to B. bassiana inoculated ash twigs for 2 h and then monitored daily for death and signs of infection for up to 10 days. All EAB adults exposed to B. bassiana were fatally infected while mean survival for control EAB was 77%. Average survival in the treatment groups for T. planipennisi and S. agrili were 99% and 83%, respectively, indicating these parasitoids are relatively unaffected by exposure to B. bassiana. This research elucidates interactions between a fungal pathogen and two parasitoids of EAB, and provides data necessary to developing a successful multi-stage integrated management approach to control of EAB.     

Phenology of Parasetigena silvestris (Diptera: Tachinidae), gypsy moth (Lymantria dispar) (Lepidoptera: Lymantriidae) larval parasitoid and its efficiency for parasitisation

Parasetigena silvestris is a univoltine, solitary, larval endoparasitoid which lays its eggs on the surface of gypsy moth larvae. Field collection of the host larvae (2nd through 5th instar) from an artificially established gypsy moth population were made to compare stage specific parasitism between larvae without and with P. silvestris tachinid eggs. The tachinid oviposition rate detected was highest in second instar larvae, and then decreased as larvae developed toward full maturity. The opposite was true for tachinid parasitoid emergence which had no emergence from second through third host instar larvae. Fourth instar gypsy moth larvae, however, experienced significantly higher parasitism by P. silvestris in the larvae with eggs than those without the eggs. The braconid wasp Cotesia melanoscelus caused significantly higher parasitism in early instar larvae with P. silvestris eggs than in those without the eggs. The tachinid prefers to lay more eggs on parasitised larvae by the braconid even though the braconid is a superior competitor to the fly during multiparasitism. Factors influencing parasitism rates by P. silvestris such as host-parasitoid synchronisation and the multiparasitism interaction with C. melanoscelus are discussed.