玉米螟赤眼蜂在甜玉米地寄生率和扩散规律的研究

调查研究了玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen在甜玉米地的年消长动态、日活动规律,以及对不同甜玉米品种和不同防治类型地亚洲玉米螟Ostrinia furnacalis (Guenee)卵的寄生率。玉米螟赤眼蜂田间扩散规律为：在苗期,按每点2000头的蜂量相距32m左右释放玉米螟赤眼蜂,即可达到50％以上的寄生率;在穗期,按每点2000头的蜂量相距24m左右释放玉米螟赤眼蜂,可达到80％以上的寄生率。     

Effectiveness of Trichogramma ostriniae and T. nubilale for controlling the European corn borer Ostrinia nubilalis in sweet corn

Seven field releases of Trichogramma ostriniae and T. nubilale (Hymenoptera: Trichogrammatidae) were made separately and in combination in a sweet corn field to compare the level of parasitism in sentinel eggs of the European corn borer, Ostrinia nubilalis (Lepidoptera: Pyralidae). The results indicate that the levels of egg parasitism among different release dates differed mainly because of changes in weather and plant architecture within the season. The level of egg parasitism by releasing T. ostriniae alone was found to be 15% higher than that by releasing T. nubilale alone, and 20% higher than by releasing the combination of the two species. Further analyses using the logistic regression model for independent and correlated data indicated T. ostriniae to be more efficient at discovering host egg masses and to have higher levels of egg parasitism than T. nubilale. Mutual interference between T. ostriniae and T. nubilale was the main factor for the lower level of egg parasitism when T. ostriniae and T. nubilale were released together. The results suggest that T. ostriniae is the better candidate for augmentative releases for control of the European corn borer, and the two species should not be released into a corn field at the same time.     

基于微卫星引物鉴别不同地理种群玉米螟赤眼蜂和螟黄赤眼蜂

不同地理种群的赤眼蜂在遗传、生理和生态适应性等方面均表现出不同程度的分化。为探究不同地理种群的玉米螟赤眼蜂Trichogramma ostriniae和螟黄赤眼蜂Trichogramma chilonis在基因型上的差异并进行准确鉴定,本研究筛选了可用以区分不同地理种群玉米螟赤眼蜂和螟黄赤眼蜂的微卫星引物。结果表明：从已报道的10对微卫星引物中,筛选出2对引物（序列号：KT834825,KT834827）可以区分玉米螟赤眼蜂中的黑龙江地理种群与吉林和辽宁两个地理种群;并筛选出2对引物（序列号：KT834822,KT834825）可以区分黑龙江、贵州和广东3个不同地理种群的螟黄赤眼蜂。该结果进一步证实赤眼蜂不同地理种群间可能存在明显的基因型差异,研究结果为精准鉴别玉米螟赤眼蜂和螟黄赤眼蜂不同地理种群,以及进一步探寻优势种群的高效繁育与应用技术奠定了理论基础。     

高温对玉米螟赤眼蜂实验种群的影响

以米蛾卵为繁育寄主,组建了玉米螟赤眼蜂在26、29、32和35 ℃下的实验种群生命表,探讨了高温对玉米螟赤眼蜂生长和生殖的影响.结果表明,高温32 ℃～35 ℃对玉米螟赤眼蜂各虫态的生长发育有明显的抑制作用.卵 幼虫的存活率在26 ℃和29 ℃分别为 94.2%和88.6%,32 ℃时下降至80.2%,而35 ℃时仅为53.2%,蛹的存活率也表现出相应的下降趋势.玉米螟赤眼蜂羽化后12 h内的抱卵量、体长及卵粒大小随温度的升高而减少或变小.26 ℃时,玉米螟赤眼蜂羽化后0～12 h的抱卵量为37.9粒,随着温度的升高,抱卵量急剧下降,29 ℃、32 ℃和35 ℃的抱卵量分别为29.6、21.6和13.7粒.在26 ℃及29 ℃时,所有雌蜂均能进行正常交配和产卵,32 ℃时有6.7%的个体不产卵,至35 ℃时,则有60%的个体不能进行正常的生殖活动.     

Overwintering of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) within target and non-target host eggs

Trichogramma ostriniae was imported into the USA from China and it continues to be evaluated as a biological control agent against the European corn borer and other lepidopteran pest species. A natural enemy's ability to overwinter is a facet of its biology with important ramifications for biological control and non-target effects. Thus, studies were conducted to examine the ability of the introduced egg parasitoid to survive over winters in central New York State. Eggs of Ostrinia nubilalis, Ephestia kuehniella, Trichoplusia ni, Helicoverpa zea and Utetheisa ornatrix were subjected to parasitism by adult T. ostriniae and then placed out of doors and exposed to winter conditions. For trials initiated in 2003 and 2004, the adult parental wasps were exposed to a diapause-inducing photoperiod and temperature regime in the laboratory; in 2010, parental wasps were conditioned out of doors and prior to the onset of winter conditions. Emergence of their progeny was monitored over time by taking aliquots of parasitised eggs, and holding them under warm conditions until emergence was complete. The level of wasp emergence generally displayed a decline followed by gradual increase until spring. Levels of overwintering ranged from 1% for O. nubilalis to 76% for E. kuehniella, and logistic regression indicated that the odds of overwintering was dependent on the year, host species, time out of doors and varied over exposure time depending on host. The potential to overwinter in New York was further confirmed by positive identification of T. ostriniae from naturally occurring O. nubilalis eggs collected from field sites where augmentative releases had been made in previous years.     

Wolbachia在玉米螟赤眼蜂内的三重感染

Wolbachia是一类广泛存在于节肢动物体内的共生菌。玉米螟赤眼蜂Trichogramma ostriniae是我国玉米田间的优势赤眼蜂种, 据报道, 赤眼蜂种内有Wolbachia感染。本文利用Wolbachia的16s rDNA和wsp基因引物通过PCR方法对玉米螟赤眼蜂的野生种群进行了调查, 发现以wsp基因为鉴定依据, 检测的所有个体都感染了3种Wolbachia ［wOstGDAa (GenBank accession no. EU157103), wOstGDAb (GenBank accession no. EU157104) 和 wOstGDB (GenBank accession no. EU157105)］。本文首次报道了野生赤眼蜂种群内Wolbachia的三重感染率几乎为100%。根据本研究的结果, 可以推测当不同种赤眼蜂寄生同一寄主时, Wolbachia可能会在不同赤眼蜂种间进行横向传播。     

转Bt基因玉米Bt11花粉对玉米螟赤眼蜂繁殖和存活的影响

在室内评价了表达Cry1Ab杀虫蛋白的转基因抗虫玉米Bt11花粉作为食物对玉米螟赤眼蜂Trichogramma ostriniae雌蜂寿命、繁殖力、子代羽化数和性比的影响。结果显示,Bt11玉米花粉中含有115.13±7.29 ng/g FW Cry1Ab杀虫蛋白。饲喂水+Bt玉米花粉和水+对照玉米花粉的雌蜂寿命、繁殖力和子代羽化数明显高于只提供水的处理,但性比没有显著差异。饲喂10%蜂蜜水的雌蜂寿命、繁殖力和子代羽化数与饲喂10%蜂蜜水+Bt玉米或10%蜂蜜水+对照玉米花粉的处理雌蜂相似,没有显著差异。饲喂水+玉米花粉和只提供水的各处理的寿命、繁殖力和子代羽化数均显著低于蜂蜜水+玉米花粉和只提供蜂蜜水的各个处理,但性比显著高。饲喂水+Bt玉米花粉与水+对照玉米花粉之间以及蜂蜜水+Bt玉米花粉与蜂蜜水+对照玉米花粉之间的寿命、繁殖力和子代羽化数没有显著差异。由此得出结论,同只提供水相比,玉米花粉可以提高玉米螟赤眼蜂的寿命和繁殖力。表达Cry1Ab杀虫蛋白的Bt11玉米花粉对玉米螟赤眼蜂的寿命、繁殖力、子代羽化数和性比无不利影响。     

Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) response to relative humidity with and without host cues

Trichogramma ostriniae is a parasitoid wasp species that is used as a biological control for several lepidopteran agricultural pests. Our study examined the effects of relative humidity (RH) on the behaviour of female T. ostriniae. In Y-tube RH choice assays, wasps generally chose higher RH over lower RH but the latency time taken to make a choice displayed no clear patterns that could be ascribed to the magnitude of the RH difference between arms of the Y-tube. In trials conducted in glass arenas with fixed humidities, the conditional probabilities of transition from searching to interacting with the leaf disk, and from interacting with leaf disks to antennal egg drumming and oviposition, were not significantly different among the RH levels, nor were there differences in latency times. These findings suggest that the level of RH may influence habitat choice but have little effect on search efficacy.     

Importance of plant size, distribution of egg masses, and weather conditions on egg parasitism of the European corn borer, Ostrinia nubilalis by Trichogramma ostriniae in sweet corn

Trichogramma ostriniae (Hym: Trichogrammatidae), an egg parasitoid of the European corn borer, Ostrinia nubilalis (Lep: Pyralidae), were released into sweet corn (Zea mays L.) fields to study the effects of weather, plant size and distribution of egg masses on egg parasitism by the wasp. Sentinel European corn borer eggs were stapled onto leaves located in the upper, middle and lower third of sweet corn plants 5 to 35 meters away from the wasp release point in either a radial or grid manner. Weather conditions and plant architecture were monitored during the experiments. Logistic regression was used to analyze the data. The results indicated that percentage of eggs parasitized was negatively related to an increase in leaf area as well as an increase in distance eggs were located from the point of release of wasps. Eggs distributed on plants at different directions from the release point received different levels of parasitism. Eggs that were stapled onto leaves in the upper third of a corn plant received much less parasitism than those on the middle and lower third of the plant. Higher mean temperature adversely affected the level of parasitism during hotter times of the season and conversely, lower temperatures (<17 °C ) reduced the egg parasitism during cooler times of the season. The longer the exposure of eggs to wasps, the higher the level of egg parasitism. However, the levels of egg parasitism for 2 day's exposure were almost the same as that for 3 day's exposure due to the limited longevity and egg-laying behavior of the wasp. These results suggest that inundative releases of T. ostriniae should be made every two to three days, with multiple release points per hectare. In addition, weather conditions and plant architecture, especially temperature, plant height and leaf area must be taken into consideration to optimize levels of parasitism.     

温度对麦蛾卵繁育的玉米螟赤眼蜂发育和生殖的影响

玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen是玉米螟的重要卵寄生性天敌,控制适宜的温度有利于室内大规模繁育。本试验以麦蛾卵为寄主,研究了不同温度(18℃、20℃、23℃、25℃、28℃、30℃、33℃、36℃)对玉米螟赤眼蜂的寿命、生殖力、子代羽化率和发育历期的影响。结果表明,20℃-25℃条件下雌蜂寿命最长,达7.9-9.0 d。在18℃-30℃亲代生殖力和子代羽化率无显著差异,亲代产卵量为40.9-61.7粒;羽化率为74.31%-84.22%。玉米螟赤眼蜂从卵到羽化的发育历期随温度的升高而显著缩短,由18℃时的22.6 d缩短至33℃的7.0 d。36℃时,雌蜂的寿命仅为0.56 d,且不能进行正常的生殖活动。因此,室内用麦蛾卵大规模繁育玉米螟赤眼蜂,适宜的温度为28℃-30℃;仅保存蜂种时,可选用温度18℃-20℃。     

挥发性信息化合物对玉米螟赤眼蜂寄主选择行为的影响

在实验室条件下,利用“Y”型嗅觉仪测定了源于寄主亚洲玉米螟Ostrinia furnacalis (Guenée) 鳞片、卵表以及不同生理阶段的雌蛾附腺的不同浓度的提取物对玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen寄主选择行为的影响,并对其引诱作用大小进行了比较。结果表明： 亚洲玉米螟鳞片的正己烷提取物在0.5 mg/mL和 1 mg/mL浓度时对玉米螟赤眼蜂有明显的引诱作用; 寄主卵的正己烷提取物在5块卵/mL和10块卵/mL浓度时对玉米螟赤眼蜂有显著的引诱作用,而在40块卵/mL浓度时对玉米螟赤眼蜂有极显著的驱避作用; 玉米螟赤眼蜂对亚洲玉米螟交配未产卵和产卵后前期的雌蛾附腺提取液有反应,而对处女蛾和产卵后期的附腺提取液没反应。卵表提取物和附腺提取物比鳞片提取液对赤眼蜂引诱作用强,两者对赤眼蜂的引诱作用没有明显差异。     

四种杀菌剂对玉米螟赤眼蜂酚氧化酶活性的影响

为明确杀菌剂对玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen毒性大小及其成蜂体内酚氧化酶（phenoloxidase, PO）活性影响, 本实验通过测定三唑酮（triadimefon）、 肟菌脂（trifloxystrobin）、 咪鲜胺（prochloraz）、 申嗪霉素（phenazino-1-carboxylic acid）4种杀菌剂对玉米螟赤眼蜂的急性毒性, 并分别测定活体和离体条件下各杀菌剂处理后酚氧化酶的比活性。结果表明, 各药剂对赤眼蜂的急性毒性大小为： 三唑酮＞咪鲜胺＞肟菌酯＞申嗪霉素, 其LC₅₀值分别为3.27, 6.46, 4.06和 9.72 mg/L, 其安全系数依次为0.07, 0.10, 0.20和1.47, 其中申嗪霉素为中等风险性, 其余3种药剂为高风险性, 且杀菌剂明显激活了PO的活性。活体条件下亚致死剂量处理得到的PO比活力高于离体处理, 且三唑酮处理组具有明显的剂量效应。本实验为研究杀菌剂对赤眼蜂的毒性及对PO的影响作了初步的探索, 为进一步研究赤眼蜂对杀菌剂的抗性及免疫能力奠定基础。     

玉米螟赤眼蜂雌蜂繁殖力与年龄的关系

以米蛾卵作为繁育寄主,通过系统解剖不同发育期（0～144 h）玉米螟赤眼蜂的卵巢,探讨了雌蜂抱卵量、繁殖力与其年龄和个体大小之间的关系。结果表明,玉米螟赤眼蜂在羽化初期（0～3 h）,卵巢中只有部分卵处于成熟状态,随着雌蜂年龄的增加,其抱卵量不断增加,至72 h时接近其卵巢容纳量。抱卵量与雌蜂年龄之间的关系可以用以下公式来表示：y =a｛1-exp［-b(x+c)］｝。用后足胫节长度（HTL）来表示雌蜂个体大小时,HTL短于0.150 mm、介于0.150～0.159 mm之间以及长于0.160 mm的个体羽化后24 h的平均抱卵量分别为40.4、50.5和58.2粒,各占其卵巢容纳量的72.8%、79.3%和86.9%,占整个成虫期总产卵量的49.4%、47.9%及51.9%。玉米螟赤眼蜂羽化后24 h内的产卵量接近于羽化后24 h的抱卵量。雌蜂个体大小与抱卵量及总产卵量之间关系密切,抱卵量与总产卵量随着雌蜂个体的增大而不断增加,呈线性正相关。个体大小可以作为评估玉米螟赤眼蜂生殖潜能高低的一个良好的指标。     

玉米螟赤眼蜂种群特异分子标记构建及其应用

赤眼蜂是我国乃至世界范围内应用最广的卵寄生蜂,其中玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen是我国玉米种植区重要的天敌昆虫,但其不同的地理种群在生物防治效果上存在较大差异。为了有效利用玉米螟赤眼蜂的优势种群,有必要对其进行准确的鉴别。然而,采用传统形态学方法对同一种赤眼蜂的不同种群进行鉴别是非常困难的。本研究首先采用随机扩增多态性DNA(RAPD)标记对采自我国北京农科院、山东日照和山西太原的3个玉米螟赤眼蜂种群,进行了遗传差异分析,然后筛选了种群特异性位点,并通过克隆测序和引物设计构建了种群特异性分子标记,即序列特征性扩增区域(SCAR)标记。最后,利用SCAR标记对混合蜂群竞争试验结果进行了分子检测。该研究方法有助于玉米螟赤眼蜂优势种群的筛选,对于赤眼蜂的有效利用具有重要的意义。     

玉米螟赤眼蜂(Trichogramma ostriniae)寄主标记信息素和学习经历对产卵行为的影响

报道了标记信息素和雌蜂经历对玉米螟赤眼蜂Trichogramma ostriniae产卵行为的影响。研究结果表明,玉米螟赤眼蜂的寄主标记信息素是在其产卵过程中的收场阶段由产卵器产生的,并且标记在寄主卵表的化学物质;玉米螟赤眼蜂对标记信息素的识别不具有先天性,其必须先用产卵器插入寄生卵来检测是否被寄生,然后其触角不停地敲击,通过学习获得对标记信息素的识别能力,从而放弃了对寄生卵的选择,学习对初始放弃时间有着重要影响,改善了其对寄主搜索效率,这种学习行为是与寄主联系在一起学习的,它能根据寄主被寄生与否而对标记信息素作出反应与不反应。该研究丰富了生态学理论,为其在生防中更好的应用提供了科学依据。     

卵液成分改变及卵表涂施引诱剂对玉米螟赤眼蜂产卵发育的影响

试验通过部分改变人造卵卵液成分和在人造卵表涂施引诱剂2种途径来试图提高人造卵繁育玉米螟赤眼蜂Trichogramma ostriniae Panget Chen的成功率。结果表明,不同比例的亚洲玉米螟OstriniafurnacalisGuenée幼虫和蛹匀浆替代部分柞蚕蛹匀浆后,对赤眼蜂寄生率有明显提高,但赤眼蜂在人造卵内的化蛹率和羽化率均较低,赤眼蜂发育至老熟幼虫因卵液过剩而被淹死;在原卵液卵表涂施亚洲玉米螟卵和鳞片正己烷提取液后,评价繁蜂成功率的各项参数都有明显提高,赤眼蜂可以完成发育,羽化成蜂,但繁蜂成功率还较低。综合上述试验结果,应用人造卵繁殖玉米螟赤眼蜂研究重点要解决卵液过剩以及其它相关的营养学问题。     

玉米螟赤眼蜂雄性生殖力的研究

根据膜翅目寄生蜂未受精的卵发育为雄性个体,受精卵发育成雌性个体这一性别决定机制,考察了玉米螟赤眼蜂雄蜂生殖力的大小,探讨了雄蜂授精能力与个体大小、年龄及交配次数之间的关系。结果表明,玉米螟赤眼蜂雄蜂在羽化时或羽化后很短的时间内其精巢就已发育成熟,成虫期不再形成新的精子。雄蜂在羽化后立即可与雌蜂进行交配,在雌蜂过量的情况下,24 h内就可能将体内的精子或精液消耗尽,24 h后的雄蜂虽能与雌蜂继续交尾,但雌蜂所繁育的子代中未见有雌性个体。同一雄蜂能与多头雌蜂进行交尾,授精8～23头雌蜂,平均能繁育出346.15头雌性后代。雄蜂的授精能力与交配次数密切相关,授精量随交配次数增加而逐渐下降。首次交配时,雄蜂能给雌蜂提供较多的精子,约能繁育出58.85头雌性后代,但随着交配次数的增加,雄蜂向雌蜂输送的精子越来越少,10次交配之后,雄蜂所能授精、繁育的子代雌性数将不超过10头。以后足胫节长度表示个体大小时,体型较大的雄性个体进行多次交配的能力强,能繁育更多的雌性后代。     

Acute and sublethal effects of neonicotinoids and pymetrozine on an important egg parasitoid,Trichogramma ostriniae (Hymenoptera: Trichogrammatidae)

Both neonicotinoids and pymetrozine are important insecticides and may have the potential to be used in combination with natural enemies in integrated pest management (IPM). However, to determine their compatibility with biological control, it is necessary to examine the side effects of these chemicals on natural enemies. We examined the acute and sublethal effects of four commonly used neonicotinoid insecticides, imidacloprid, dinotefuran, nitenpyram and thiamethoxam, and the pyridine azomethine, pymetrozine, on adults of Trichogramma ostriniae. By analysing acute toxicity and evaluating the safety quotient of these chemicals, we found that thiamethoxam and dinotefuran pose extremely high risks to T. ostriniae, imidacloprid and nitenpyram posed high risks, but pymetrozine was found to have a low risk. In terms of sublethal effects, longevities of female wasps were significantly shortened when they were exposed to residues of dinotefuran. Percentages of ovipositing females decreased significantly after exposure to pymetrozine, thiamethoxam and dinotefuran. Numbers of offspring per female were significantly lower when females were exposed to pymetrozine, dinotefuran or thiamethoxam, compared with control females. Percentages of offspring that emerged as adults were lower when parental females were exposed to either pymetrozine or imidacloprid. Based on the results of the sublethal concentration assay and the acute toxicity bioassay, nitenpyram would be safe for IPM programmes utilising T. ostriniae, and we suggest that T. ostriniae could be released safely after foliar applications of nitenpyram. However, foliar application of imidacloprid, thiamethoxam, dinotefuran or pymetrozine in an agro-ecosystem where T. ostriniae is a predominant biocontrol agent should be carefully evaluated.     

艾叶精油对玉米螟赤眼蜂的影响及两者对米蛾的联合作用

玉米螟赤眼蜂是生物防治中一种重要的天敌昆虫,为探明艾叶精油对玉米螟赤眼蜂的影响及两者对米蛾的联合防治效果,本文研究了艾叶精油熏蒸、触杀、驱避活性对玉米螟赤眼蜂的影响及艾叶精油和玉米螟赤眼蜂对米蛾的联合作用。结果表明,艾叶精油熏蒸和触杀处理对玉米螟赤眼蜂卵具有明显影响,寄生在米蛾卵上的玉米螟赤眼蜂卵经0.1、0.2、0.3、0.4、0.5、0.6μg/cm3艾叶精油熏蒸处理72h后玉米螟赤眼蜂的羽化率分别为56.67%、49.33%、44.00%、33.33%、26.00%和14.67%;寄生在米蛾卵上的玉米螟赤眼蜂卵经100、200、300、400、500、600mg/L艾叶精油触杀处理72h后玉米螟赤眼蜂的羽化率分别为54.00%、45.33%、38.00%、28.67%、18.00%和6.00%,均与对照组表现出显著性差异。艾叶精油驱避活性对玉米螟赤眼蜂成蜂也有明显的影响,300mg/L艾叶精油对玉米螟赤眼蜂的驱避率79.05%,随着时间间隔和距离间隔的增加,这种影响作用降低;联合应用艾叶精油与玉米螟赤眼蜂时先释放玉米螟赤眼蜂,24h后再滴加艾叶精油的防治效果最佳,米蛾的死亡率可高达96%。     

棉田四种常用杀虫剂对玉米螟赤眼蜂不同虫态的杀伤力

棉田四种常用杀虫剂对玉米螟赤眼蜂不同虫态的杀伤力差异显著。溴氰菊酯、氰戊菊酯、久效磷、甲胺磷对玉米螟赤眼蜂成虫的杀伤力均很强;溴氰菊酯和甲胺磷对玉米螟赤眼蜂卵至蛹各个虫态的杀伤力较强;而氰戊菊酯对卵、久效磷对幼虫有较强的杀伤力。久效磷对玉米螟赤眼蜂成虫的残留毒杀力最强。玉米螟赤眼蜂成虫是玉米螟赤眼蜂一生中对农药最敏感的时期,其次是卵和幼虫,而预蛹和蛹耐药性较强。