Insecticidal activities of secondary metabolites of endophytic Pencillium sp. in Derris elliptica Benth

Abstract:  A strain of endophytic Pencillium sp., which might produce rotenone or its analogues and showed bioactivity against aphids, was isolated from the fresh roots of Derris elliptica Benth. A total of 12 fractions, isolated from the chloroform extract of endophytic Pencillium sp. mycelia by silica gel column, were tested by bioassay and high-performance liquid chromatography (HPLC), and the more bioactive fractions were found to be D, E and J. Against the adult turnip aphid, Lipaphis erysimi , by dipping at a concentration of 1 mg/ml, the corrected mortalities of fraction D, E and J were 57.68, 63.28 and 69.74% after 48 h of treatment respectively. The three fractions also showed strong antifeeding activity against third instar larvae of Plutella xylostella in a laboratory bioassay. One absorption peak was detected in the HPLC picture of fraction D, it had a similar retention time as that of rotenone, and the chemical constituent, related to the absoption peak, had the same ultraviolet absorption picture as that of rotenone. Then it could be further concluded that the bioactive compounds in the fraction D could be rotenone or its analogous compounds.     

菜蚜茧蜂对六种杀虫剂抗药性的季节性变化

采用药膜法研究了福州建新和闽侯上街菜蚜茧蜂Diaeretiella rapae对杀虫剂抗药性的季节性变化。田间菜蚜茧蜂种群在网室内脱离选择压力后对杀虫剂敏感性显著升高。与敏感的F₂₁子代的LC₅₀相比,2002年6月8日至2004年11月18日期间,建新菜区菜蚜茧蜂对甲胺磷、氟虫腈、阿维菌素、氰戊菊酯和吡虫啉的抗性倍数分别为11.8～31.2,9.3～14.7,9.3～35.7,7.0～16.6,和13.3～30.1倍;2003年6月5日至2004年12月17日期间,上街菜区菜蚜茧蜂对甲胺磷、氟虫腈、阿维菌素、氰戊菊酯和吡虫啉的抗性倍数分别为7.5～34.9,4.0～14.3,9.2～38.6,7.8～18.9和12.1～24.2倍。田间菜蚜茧蜂种群在5月份和6月初抗性水平最高,12月份较低,6月末最低,尤其在6月份期间20天内抗性水平急剧下降。研究结果表明,田间菜蚜茧蜂对6种杀虫剂的抗性水平在脱离选择压力后不稳定,且呈显著的季节性变化。表2参25     

EFFECTS OF HOST PLANTS ON POPULATION DYNAMICS OF LIPAPHIS ERYSIMI (KALT.) IN THE FIELD

Abstract The population dynamics of alates and apterous of turnip aphid (TA) Lipaphis erysimi (Kalt.) together with the incidence of parasitism by Diaeretiella rapae (M'Intosh) on five host vegetable varieties in the field were evaluated. The results showed that the average populations of TA apterous on host vegetable varieties turnip, Chinese kale, leaf mustard, flowering cabbage and Chinese cabbage were 63. 425, 10. 041, 24. 928, 23. 323 and 114. 308 aphids/plant, respectively. The 'critical day' was used to estimate the date when TA population density on host vegetable varieties reaches its economic threshold. The relationship between TA apterous population ( x ) and mummy aphids parasitized by parasitoid D. rapae was significant, and the regression formula is y = 0. 1211 + 0. 01431 (r=0. 9739**).     

桃蚜、萝卜蚜的种内密度和种间竞争效应

在温室内不同密度条件下,研究了桃蚜和萝卜蚜在甘蓝上的种内密度效应和种间竞争作用。结果表明：单独饲养时,在5头／株和10头／株密度下,两种蚜虫种内密度效应均较弱;而在15头／株时,桃蚜和萝卜蚜的寿命和产蚜量都随之显降低,说明当两种蚜虫达到一定的拥挤程度时,种内密度对种群均产生一定的负效应。两种蚜虫共存时,单头产蚜量均比单独饲养时显下降,种问竞争作用明显。在10、15头／株密度下,桃蚜的竞争作用大于萝卜蚜,萝卜蚜的寿命和单头产蚜量都极显低于桃蚜。     

植物提取物对萝卜蚜的室内毒力研究

采用浸叶法和Potter喷雾法测定七种植物提取物对萝卜蚜 (Lipaphiserysim)的室内毒力效果。研究结果显示 :巴豆、博落回和醉鱼草提取物对萝卜蚜的致死中浓度LC50 分别为 1 86.94mg/L、2 0 0 .75mg/L和 1 5 7.73mg/L。     

田间不同品种蔬菜对萝卜蚜种群的影响(英文)

本试验通过利用５个品种蔬菜（萝卜,芥蓝,芥菜,菜芯和白菜）研究萝卜蚜（Ｌｉｐａｐｈｉｓ ｅｒｙｓｉｍｉ）在不同蔬菜上的种群动态以及对寄生于萝卜蚜的菜蚜茧蜂（Ｄｉａｅｒｅｔｉｅｌｌａ　ｒａｐａｅ）种群的影响。研究结果显示,在３０天研究期间,有翅萝卜蚜的平均虫口（蚜虫数／苗）在萝卜、芥蓝、芥菜、菜芯和白菜苗上分别为３．９１８、０．８３１、１．１４９、１．７４３和５．２３头,表明降落在萝卜苗上的有翅蚜数量显著地比在其它蔬菜苗上的高;而无翅萝卜蚜的中均虫口分别为６３．４２１、１０．０４１、２４．９２８、２３．３２３和１１４．３０８头,说明萝卜蚜无翅蚜在白菜上的种群显著地高于其它品种蔬菜上的。由于萝卜蚜在不同品种蔬菜上的种群不同,导致菜蚜茧峰种群在不同品种蔬菜上也不同,其僵蚜虫口分别为１．０５６、０．２５１、０．２７７、０．６５１和１．４４头,显示了在萝卜和白菜上的僵蚜数量显著地比其它蔬菜上的高。分析结果表明,萝卜蚜的种群（ｘ）与菜蚜茧峰的种群（ｙ）呈显著的相关关系：ｙ＝０．１１８８＋０．０１４３ｘ（ｒ＝０．９７３９）。本研究还利用试验结果提出了萝卜蚜无翅蚜种群从蔬菜在田间种植后达到防治指标（５０头／苗）的临界天数（ｃ     

Contributions of climate,plant phenology and natural enemies to the seasonal variation of aphids on cabbage

Brevicoryne brassicae (L), Lipaphis erysimi (Kalt) and Myzus persicae (Sultzer) (Homoptera: Aphididae) form the aphid complex that causes great losses in Brassicaceae in tropical and subtropical regions. Knowledge of their population dynamics is important for the development of integrated pest management programmes. This study aimed to investigate the effects of cabbage phenology, climatic factors and natural enemies populations on the dynamics of these organisms, and the factors regulating their predators’ occurrence. The densities of aphids and their natural enemies and the climate were monitored for two years in 16 cabbage crops. The highest densities of the aphids occurred during periods of relative humidity (RH) drop, a condition that affects them positively. Regarding the predators, the factors affecting their abundance varied but RH was positively related to most of them. This study provides relevant insights into the factors that regulate the aphids in cabbage and for the decision‐making process of control of these severe pests.     

Positive correlation of methamidophos resistance between Lipaphis erysimi and Diaeretilla rapae and effects of methamidophos ingested by host insect on the parasitoid

Temporal and spatial correlated variations on the methamidophos resistance and biomolecular rate constant of acetylcholinesterase to insecticides were found between the turnip aphid, Lipaphis erysimi and its endoparasitoid, Diaeretilla rapae , collected from field colonies and an insecticide-free field insectarium in Fujian, China. Compared to the related susceptible insectarium population, L. erysimi and D. rapae displayed 7.4–29.2- and 2.6–9.2-fold resistance ratios, respectively. In addition, two populations of L. erysimi with different methamidophos resistance levels, that is, a field (with 5.8-fold resistance ratio) and an insectarium population, were used to study the effects of methamidophos ingested by the host insect on D. rapae development. The percentage of D. rapae cocoon formation decreased significantly when the parasitized L. erysimi were fed on cauliflower leaves treated with methamidophos at lethal concentration dosages 10 (LC₁₀) or LC₅₀. At LC₅₀ dosages the percentage of D. rapae cocoon formation and adult emergence decreased significantly. When the parasitized L. erysimi were fed on methamidophos at LC₉₀ dosage, no D. rapae cocoons were found. When the field or insectarium L. erysimi were treated with methamidophos at LC₁₀, the susceptibility to methamidophos in the adult D. rapae emerged from the treated host insect was similar to the control. However, the susceptibility to methamidophos in the adult D. rapae became lower than the control when the host insects were treated at LC₅₀ dosages. The data thus suggested that the methamidophos ingested by the host insect L. erysimi could be an important factor in the endoparasitoids' insecticide resistance development. The natural selectivity would favor the parasitoids that had developed an insensitivity to the insecticide(s).     

Free amino acid content of phloem sap from Brassica plants in relation to performance of Lipaphis erysimi (Hemiptera: Aphididae)

Cultivars of Brassica juncea, B. napus and B. campestris, differing in host-suitability to the mustard aphid (Lipaphis erysimi pseudobrassicae Kalt.), were analysed for their phloem sap content of free amino acids. Sap was collected from excised mustard aphid stylets and analysed by means of high performance liquid chromatography. Aspartic and glutamic acid were, together with glutamine, the dominating amino acids. All plants had very little glycine, γ-aminobutyric acid (GABA), methionine and tryptophan in their sap. This amino acid pattern closely resembled that of cereals. The total concentration and the individual composition of amino acids were not found to be related to the level of aphid resistance previously found in the investigated Brassica species. However, one B. campestris cultivar, yellow sarson YSB-9, on which the aphids were shown to grow more slowly, had less amino acid content than other B. campestris varieties. The slow population growth of aphids on B. juncea, compared to that on B. campestris, is probably due to other than nutritional factors.     

萝卜蚜和豆蚜染色体C-带带型比较与分析

本研究利用C-带技术,显示出萝卜蚜和豆蚜的染色体C-带带型,并进行了初步分析。萝卜蚜与豆蚜的染色体在组型上只有第4对染色体稍有区别;在带型上两者有很明显的差异。萝卜蚜有2对散漫着丝粒染色体,豆蚜没有该种染色体。豆蚜的第4对染色体在端部缺少-C带带纹。萝卜蚜的第2对染色体与豆蚜的第2对染色体带型相似。根据萝卜蚜和豆蚜的C-带带型,讨论了二者在进化中的亲缘关系。