茶足柄瘤蚜茧蜂对苜蓿蚜的寄生功能反应

在室内(25±1℃,L:D=16:8光周期,RH=40%～60%)条件下,研究了茶足柄瘤蚜茧蜂Lysiphlebus testaceipes(Cresson)对苜蓿蚜Aphis craccivora(Koch)若蚜的寄生功能反应。结果表明:苜蓿蚜的龄期对茶足柄瘤蚜茧蜂的寄生作用有很大影响,用功能反应HollingⅡ模型模拟,其模拟方程为Na=1.118 N/(1+0.0184 N)。通过该方程可明确单头雌成蜂在24 h内最多寄生60.60头苜蓿蚜,其寄生1头苜蓿蚜所需时间为0.396 h。在5个温度梯度下,茶足柄瘤蚜茧蜂对苜蓿蚜的寄生功能反应均符合HollingⅡ模型,但不同温度下的功能反应参数有明显的差异。此外茶足柄瘤蚜茧蜂自身密度对寄生有一定的干扰作用,其干扰作用通过Hassell-Varley模型拟合,方程为a=0.0621P-0.3062,表明茶足柄瘤蚜茧蜂雌蜂的发现域随着自身密度的增加而逐渐变小,寄生蜂雌蜂个体间的相互干扰效应降低了寄生效能。     

Parasitoids as vectors of facultative bacterial endosymbionts in aphids

Heritable bacterial endosymbionts play an important role in aphid ecology. Sequence-based evidence suggests that facultative symbionts such as Hamiltonella defensa or Regiella insecticola also undergo horizontal transmission. Other than through male-to-female transfer during the sexual generation in autumn, the routes by which this occurs remain largely unknown. Here, we tested if parasitoids or ectoparasitic mites can act as vectors for horizontal transfer of facultative symbionts. Using symbiont-specific primers for diagnostic PCR, we demonstrate for the first time, to our knowledge, that parasitoids can indeed transfer H. defensa and R. insecticola by sequentially stabbing infected and uninfected individuals of their host, Aphis fabae, establishing new, heritable infections. Thus, a natural route of horizontal symbiont transmission is also available during the many clonal generations of the aphid life cycle. No transmissions by ectoparasitic mites were observed, nor did parasitoids that emerged from symbiont-infected aphids transfer any symbionts in our experiments.     

Leaf surface factors of transgenic Bt cotton associated with the feeding behaviors of cotton aphids: A case study on non-target effects

The present paper reports case study results of the risk assessment of transgenic Bt cotton on a non-target pest, cotton aphid, Aphis gossypii. Several types of techniques, i.e., electrical penetration graph (EPG), light and electron microscopy, bioassays and chemical analysis, were applied to investigate physical and chemical leaf factors of 2 transgenic Bt cotton lines (GK12 and GK19) and their pa-rental non-Bt cotton line (Simian3) associated with searching and feeding behaviors of cotton aphids on leaves or leaf extracts of cotton plants. EPG results showed that there were some differences among behaviors of cotton aphids on 2 Bt cotton and 1 non-Bt cotton lines. Cotton aphids performed similarly to leaf surface extracts from 3 cotton lines; and leaf surface chemicals, mainly volatiles and waxes, were almost identical in the components and concentrations among the cotton lines. However, three cotton lines were quite different from each other in the densities of certain kinds of covering trichomes. Therefore, the relationships between the physical characteristics and the searching behaviors of cotton aphids on the three cotton lines were constructed as the regression equations. Glandular trichomes and covering trichomes with 5 branches influenced the cotton aphids' searching behaviors effectively; and other trichomes with other branches affected aphids in varying ways. These results demonstrated that leaf surface physical factors of transgenic Bt cotton lines different from their parental non-Bt line could affect the penetration behaviors of non-target cotton aphids. Cotton aphids penetrate and feed more easily on two Bt cotton lines than on the non-Bt cotton line.     

Parasitoids associated with the common pistachio psylla, Agonoscena pistaciae, in Iran

The parasitoids associated with the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer, were investigated at three pistachio plantations in Rafsanjan, Iran. Of the 6504 wasps emerging from mummified psyllids, 46% were the primary parasitoid Psyllaephagus pistaciae Ferrière, and the remaining 54% represented six species of hymenopterous hyperparasitoids, including Chartocerus kurdjumovi (Nikol’skaja), Marietta picta (André), Pachyneuron aphidis (Bouché), Pachyneuron muscarum (Linnaeus), Psyllaphycus diaphorinae (Hayat), and Syrphophagus aphidivorus (Mayr). Lysiphlebus fabarum Marshall, the parasitoid of Aphis gossypii Glover and Aphis craccivora Koch present on weeds, was found to be an alternative host for three major hyperparasitoids of A. pistaciae. The most abundant hyperparasitoid was S. aphidivorus, appearing during the growing season in all trial locations on psyllids and aphids in pistachio orchards. The weed-infesting aphids, along with their primary parasitoid, can act as a reservoir of A. pistaciae secondary parasitoids. Therefore, parasitized aphids allow populations of secondary parasitoids to increase and consequently to apply higher pressure on P. pistaciae. We detected that two primary parasitoid species, including P. pistaciae and L. fabarum, attacking different species of hosts interact indirectly through shared secondary parasitism. It is suggested that the community structure of A. pistaciae may be influenced by apparent competition, although more work is needed to provide firm evidence.     

Selecting arthropod biological control agents against arthropod pests: Can the science be improved to decrease the risk of releasing ineffective agents?

With greater emphasis being placed on management of the risks attached to natural enemy releases for biocontrol programs and the need to justify research budgets, the efficient selection of effective natural enemies is increasingly important. Historically there has been little agreement regarding how or whether this can be accomplished. Recent studies have demonstrated that there is good correspondence between insect host-finding behavior and attack rates in well-designed laboratory studies and their performance of this behavior in the field. Success in measuring efficacy of candidate agents remains somewhat of an art due to the multitude of factors influencing efficacy, but will be improved by attention to: (1) characterization of natural enemy candidates using morphological taxonomy or genetic markers at the onset of a program, (2) climatic matching candidate agents when possible, and (3) evaluations in semi-field or field cage conditions following quarantine evaluations whenever possible before proceeding with widespread releases. The application of these principles is discussed in regard to US biocontrol programs for Bemisia tabaci (Gennadius), Lygus spp., and Aphis glycines Matsumura. Proper project planning and interdisciplinary cooperation will enhance the chances for a successful project.     

棉花型和黄瓜型棉蚜对寄主植物的适合度

采用寄主转换建立生命表及触角电位 (EAG)方法比较了棉蚜两寄主专化型 (棉花型和黄瓜型 )对不同夏季作物的适合度。结果表明 ,棉花型蚜转到黄瓜上及黄瓜型蚜转接到棉花上均不能正常产仔繁殖和建立种群。两种蚜型均不能在茄子和苋菜上建立种群。黄瓜型蚜能在豇豆上建立种群 ,但棉花型蚜不能 ,表现出两种寄主型棉蚜对夏寄主利用上存在显著差异。受棉蚜为害 12～ 36 h后的黄瓜或棉花植株仍不适合于棉花型或黄瓜型蚜 ,表现出黄瓜型蚜不能在被棉花型蚜为害过的棉株上正常存活和繁殖 ,棉花型蚜也不能在被黄瓜型蚜为害过的黄瓜苗上存活和繁殖。两种寄主型蚜对不同寄主叶片丙酮提取物的触角电位表明 ,黄瓜型蚜对棉花、哈密瓜和马铃薯叶片提取物的反应显著强于棉花型蚜 ,而对黄瓜和甜瓜叶片提取物的反应上两种蚜型差异不显著。文中同时对棉花型和黄瓜型棉蚜产生的生态机制进行了讨论。     

棉蚜体内感染沃尔巴克氏体（Wolbachia）的分子检测

Wolbachia是存在于节肢动物体内的一类呈母系遗传的细胞内共生细菌 ,这类细菌可以通过卵的细胞质传播并参与调控寄主的生殖活动。通过对Wolbachia外膜蛋白质的wsp基因进行特异性扩增 ,证实了寄生于不同植物的棉蚜 (AphisgossypiiGlover)体内均有感染 ,说明Wolbachia可能广泛存在于棉蚜体内 ,扩增出的Wolbachia目的片段为 5 90bp左右。通过对棉蚜体内感染的Wolbachia的wsp基因序列进行分子检测 ,为进一步研究棉蚜的孤雌生殖与Wolbachia的相关关系等奠定基础。     

Functional response of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) to Aphis gossypii Glover (Homoptera: Aphididae) in the Laboratory

Stage specific functional response of Harmonia axyridis (Pallas) to varying densities of Aphis gossypii Glover was examined in a simplified cucumber leaf arena under laboratory conditions. All stages of H. axyridis were isolated individually for 24 h with different prey densities at 25 °C and a photoperiod of 16:8 (L:D) h. The number of prey consumed by the predator was checked at 3, 6, 12, and 24 h. All stages of H. axyridis showed a Type II functional response. Based on the random predator equation, estimated attack rates of H. axyridis at 24 h were 0.0037, 0.0442, 0.3590, 0.3228, and 0.1456, and estimated handling times were 4.1001, 2.4575, 0.7500, 0.2132, and 0.1708 h for the first, second, third, and fourth instars, and female adult, respectively.     

中国蚜属分亚属的研究及一新亚属和一新纪录亚属(同翅目:蚜科)

经研究认为蚜属Aphis Linnaeus应分为8个亚属,即增加一新亚属：点蚜新亚属Aphis(Maculaphis)subgen.nov,模式种：Aphis Icigocola(Shinji,1924),新亚属重要的鉴别特征是腹部背板I－V至少中毛具有明显骨化的毛基斑,体背毛长且粗,给出分亚属检索素,并记述中国1新纪录亚属弓蚜亚属Aphis(Poxopterina)Boerner及中国1新纪录蒿弓蚜Aphis(Toxopterina)vandergooti(Boerner,1939).     

棉蚜2个乙酰胆碱酯酶cDNA片段的基因克隆与序列分析

采用RT－PCR技术,利用简并引物从棉蚜（Aphis gossypii Glover)中克隆出2个乙酰胆碱酯酶基因的cDNA片段,Ag,ace 1l和Ag.ace2.Ag.ace1基因的cDNA片段为282bp,编码94个氨基酸;Ag.ace2基因的cDNA片段为264bp,编码88个氨基酸。扩增获得的2个乙酰胆碱酯酶基因cDNA片段所编码的氨基酸序列均与其他昆虫的乙酰胆碱酯酶基因有很高的同源性。首次从一种昆虫中克隆出2个乙酰胆碱酯酶基因片段,为同一种昆虫中存在多个乙酰胆碱酯酶基因的假设提供了直接的分子生物学证据。