江苏地区三叶斑潜蝇和美洲斑潜蝇的发生危害及种群动态

【目的】三叶斑潜蝇Liriomyza trifolii和美洲斑潜蝇Liriomyza sativae是一类危害蔬菜、花卉的世界性害虫,也是我国重要的外来入侵害虫。了解其发生危害特征,可为这两种斑潜蝇的防治提供科学依据。【方法】于2015年对江苏地区的两种斑潜蝇的发生分布、危害程度以及在扬州地区的发生动态进行了调查,采集含有潜道的叶片,待蛹羽化为成虫后鉴定斑潜蝇种类,同时统计叶片上的潜道数量划分危害等级。【结果】美洲斑潜蝇主要在苏北地区发生危害,三叶斑潜蝇主要在苏南、苏中地区发生危害;两种斑潜蝇在江苏地区的发生危害程度均未超过3级。在扬州地区的蔬菜上仅调查到三叶斑潜蝇的危害,其危害的寄主植物有6科、12种,主要包括茄科、豆科、葫芦科、十字花科的蔬菜。三叶斑潜蝇的发生危害从3月开始,11月结束,全年有3个发生危害高峰,其中在7月下旬至8月初的发生危害最重。【结论】两种斑潜蝇在江苏地区的种类分布呈现出明显的地理差异,同时扬州地区三叶斑潜蝇的虫口密度随寄主和时间不同呈现的明显,因此生产上需加强对斑潜蝇发生危害进行监测,并指导斑潜蝇防治。     

An association between phlebotomine sandflies and aphids in the Peruvian Andes

Abstract. As the composition of natural sugars in the diet of adult sandflies (Diptera: Psychodidae: Phlebotominae) may affect the development of Leishmania (Kinetoplastida: Trypanosomatidae) in sandfly guts, and so play an important role in the epidemiology of leishmaniasis, there is increasing interest in the sources of sugars for wild sandflies. Advanced chromatography techniques have provided indirect evidence that wild sandflies feed on honeydew, a substance released by aphids (Hemiptera: Aphididae) when feeding. Our objective was to determine whether sandfly density can be influenced directly by the local density of aphids. Aphid density was determined by counting absolute numbers of aphids on alfalfa stems in Purisima Valley, Peru, where sandflies transmit Leishmania peruviana causing Andean cutaneous leishmaniasis (uta). Sandfly relative abundance was measured using sticky trap sampling repeatedly in alfalfa fields. Lutzomyia verrucarum accounted for 92% of the total sandflies collected. As there was a female bias in sandflies collected close to houses, only the numbers of male sandflies were used in analysis. Most of the adult aphids found feeding on alfalfa were either Therioaphis trifolii forma maculata (97%) or Acyrthosiphon pisum (3%). By regression analysis, a significant relationship was found between the density of Lu. verrucarum males and the density of adults of both aphid species. This is the first ecological study to support the hypothesis that aphid honeydew may be a source of sugar for sandflies.     

Transfer of clover cyst nematode resistance from Trifolium nigrescens Viv. to T. repens L. by interspecific hybridisation

 Resistance to clover cyst nematode (Heterodera trifolii) has been successfully transferred from Trifolium nigrescens to T. repens by interspecific hybridisation. A sterile triploid hybrid (H-6909-5, 2n=3x=24) was initially produced with the aid of embryo culture. The hybrid was chromosome-doubled from axillary meristems by an in vitro colchicine method. Three chromosome-doubled plants were obtained, and these showed a marked increase in pollen stainability from 10% in 3x H-6909-5 to an average of 89% (range 88–91%) in 6x H-6909-5. T. nigrescens was a source of clover cyst nematode resistance. A mean of 23 (range 0–150) cysts per plant was recorded for T. nigrescens in comparison to a mean of 150 (range 50–240) cysts per plant for T. repens. The 3x and 6x interspecific hybrids were shown to be as resistant as the most resistant. T. nigrescens genotype and were significantly lower in cyst number per gram of root dry weight than the susceptible T. nigrescens and T. repens genotypes. Received: 11 July 1997 / Accepted: 15 July 1997     

应用EPG技术分析不同品种苜蓿对苜蓿斑蚜的抗性

【目的】明确苜蓿斑蚜Therioaphis trifolii对不同品种苜蓿Medicago sativa的取食行为,探明抗蚜因子和抗虫位点,筛选抗蚜苜蓿品种。【方法】利用刺吸电位技术(electrical penetration graph, EPG)记录苜蓿斑蚜成蚜在10个苜蓿品种上的取食行为,并基于聚类分析方法筛选合适的EPG参数进行抗蚜性评价。【结果】苜蓿斑蚜成蚜在取食苜蓿过程中呈现np波、pd波、A波、B波、C波、E波、F波和G波8种波形,其中E波、F波和G波的总时间在不同品种间表现出显著差异。在5 h测试期间,E波持续时间在敖汉上最长,金皇后和中苜3号上次之,草原2号和阿尔冈金上最短;F波总时间以准格尔、阿尔冈金和金皇后上最长,敖汉、德宝和草原2号上最短,说明前者具有较强的机械抗性而后者机械抗性较弱。以第1次刺探持续时间、总刺探时间、F波总时间、C波总时间、E波总时间作为聚类分析的指标,10个苜蓿品种被聚成3类：阿尔冈金、草原2号、WL168HQ、德宝、中苜2号和新牧2号为第Ⅰ类,金皇后、中苜3号和准格尔为第Ⅱ类,敖汉为第Ⅲ类。【结论】苜蓿斑蚜成蚜在不同苜蓿品种上的取食行为存在差异,草原2号、阿尔冈金和WL168HQ在叶表皮、叶肉和韧皮部层次对苜蓿斑蚜成蚜存在抗性,金皇后在叶表皮和叶肉部位表现出抗性;苜蓿斑蚜成蚜在敖汉上能够长时间刺吸取食,因此敖汉抗性最弱。本研究为深入探讨苜蓿抗虫机理和蚜虫综合治理提供了理论参考。     

小十三星瓢虫对苜蓿斑蚜的捕食功能反应

对小十三星瓢虫Adonia variegata(Goeze)捕食苜蓿斑蚜Therioaphis trifolii(Monell)的研究表明,其功能反应为Holling-Ⅱ型模型,方程为Na=0.967N/(1+0.0095N),捕食苜蓿斑蚜的数量随斑蚜密度增加而增大,日最大捕食量为102头。在10~25℃下,小十三星瓢虫捕食率y与温度x的关系为y=3.4x-7.9375;在25~35℃间的捕食率y与温度x的关系为y=137.08-2.25x。25℃下小十三星瓢虫捕食率最高,捕食率达79.4%。在种内干扰条件下,其捕食作用率E随天敌密度P的增加而减少,干扰反应数学模型为E=0.6063P-0.6743。随着叶片数的增多,小十三星瓢虫和斑蚜之间的距离相对增大,造成捕食率的下降。     

江苏泰兴市首次发现三叶草斑潜蝇疫情

2008年7月初泰兴市植物检疫站在泰兴市泰兴镇蔬菜基地发现并采集带有斑潜蝇潜道的药芹叶片,通过对其进行形态特征和分子生物学鉴定,确认为江苏地区首次发现检疫性害虫三叶草斑潜蝇Liriomyza trifolii(Burgess)。通过黄板诱集成虫和田间寄主作物调查,对泰兴市2008-2009年发生特征及年度间、寄主间为害情况差异进行分析,并针对今后加强三叶草斑潜蝇监测与防治工作中存在的问题提出设想与建议。     

Biological control of the leafminer,Liriomyza trifolii by introduction,releasing, evaluation of the parasitoids Diglyphus isaea and Dacnusa sibirica on vegetables crops in greenhouses in Egypt

Abstract

The serpentine leafminer, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae), is one of the most serious pests of various floricultural and vegetable crops. The European strains of the parasitoids Diglyphus isaea (Walker) (Hymenoptera: Eulophidae) and Dacnusa sibirica Telenga (Hymenoptera: Braconidae) were imported from The Netherlands. A total of 90,000 of these parasitoids were reared and released on cucumber and tomato in greenhouses. The parasitism rates of D. sibirica reached maximum 11.6% and 7.2% in the 11th week from the releasing date, on cucumber and tomato, respectively. Also the parasitism rates of the European strain of D. isaea increased until it reached a maximum 2.1% and 1.4%, in the tenth week from the releasing date on cucumber and tomato, respectively. It is concluded that the parasitoids D. sibirica and the European strain of D. isaea can be established in Egypt.     

三叶斑潜蝇发生特点研究

2007—2009年在浙江杭州对三叶斑潜蝇的发生情况进行了调查。结果表明,在杭州地区范围内该虫的分布已很广,与其他斑潜蝇混合发生。春夏季以美洲斑潜蝇为害为主,6月是为害盛期。秋冬季为多种斑潜蝇混合为害,9月是混发盛期,期间以三叶斑潜蝇为害占多数。目前查到有13种寄主作物受三叶斑潜蝇为害。     

Cucurbitane Triterpenoid Oviposition Deterrent from Momordica charantia to the Leafminer,Liriomyza trifolii

Females of Liriomyza trifolii, a polyphagous leafminer, are often deterred from ovipositing on Momordica charantia leaves. The methanol extract of M. charantia leaves showed strong oviposition deterrent activity against L. trifolii females on the host plant leaf when it was dipped in the methanol extract at a concentration of 1 g of fresh leaf equivalent/ml. Bioguided fractionation of the methanol extract of the leaves of M. charantia led to the isolation of a new cucurbitane triterpenoid, 7,23-dihydroxy-3-O-malonylcucurbita-5,24-dien-19-al, along with another known compound, momordicine I. Both 7,23-dihydroxy-3-O-malonylcucurbita-5,24-dien-19-al and momordicine I respectively had significant ovipositing deterrent effect towards the adult females of L. trifolii on host plant leaves treated at concentrations of 3.25 and 33.60 μg/cm².     

A Ras protein from a phytopathogenic fungus causes defects in hyphal growth polarity, and induces tumors in mice

Ras is a low-molecular-weight guanine nucleotide (GDP/GTP)-binding protein that transduces signals for growth and differentiation in eukaryotes. In mammals, the importance of Ras in regulating growth is underscored by the observation that activating mutations in ras genes are found in many animal tumors. Colletotrichum trifolii is a filamentous fungal pathogen of alfalfa which causes anthracnose disease. To investigate signaling pathways that regulate growth and development in this fungus, a gene encoding a Ras homolog (CT-Ras) was cloned from C. trifolii. CT-Ras exhibited extensive amino acid similarity to Ras proteins from higher and lower eukaryotes. A single amino acid change resulting in mutationally activated CT-Ras induced cellular transformation of mouse (NIH 3T3) fibroblasts and tumor formation in nu/nu mice. In Colletotrichum, mutationally activated CT-Ras induced abnormal hyphal proliferation and defects in polarized growth, and significantly reduced differentiation in a nutrient-dependent manner. These results show that C. trifolii Ras is a functional growth regulator in both mammals and fungi, and demonstrate that proper regulation of Ras is required for normal fungal growth and development. Received: 20 October 1998 / Accepted: 23 April 1999