红鳍东方纯越冬试验

１９９６年１１月２１日至１９９７年５月２日和１９９８年１１月至１９９９年４月１２日的两次试验结果表明，红鳍东方Ｔｕｎ越冬水温较低或日水温差变化较大会影响成活率，应控制在１６￣１７℃较好，日水温差变化小于４℃，并在自然水温不低于１１℃时就开始升温。体长１００￣１５０ｍｍ，体重６０￣１４０ｇ的个体越冬期放养密度为１８￣３０尾／ｍ＾３。饵料中添加维生素Ｃ和Ｅ、“多维”及抗生素等，成活率为９６．５％，日增     

福建省露地及设施蔬菜烟粉虱越冬种群密度及耐寒性研究

2017年1月9—12日和2月21—24日,在南平建瓯、三明将乐、三明三元、福州闽侯、龙岩新罗以及漳州龙海等6个地区,调查了大棚和露地烟粉虱越冬寄主及种群密度,以期明确福建省露地及设施蔬菜烟粉虱越冬规律,为烟粉虱的综合治理提供理论依据。共记录烟粉虱越冬寄主6科16种,主要包括栽培蔬菜花椰菜、番茄、茄子以及阔叶类杂草龙葵、小飞蓬、辣子草和胜红蓟。在露地花椰菜上,烟粉虱越冬虫口密度1月份显著高于2月份;花椰菜采后残株上的越冬虫口密度显著高于莲座期和花球形成期。在温室大棚中,休耕大棚中越冬虫口密度显著高于生产大棚。无论是蔬菜还是杂草,温室大棚中的越冬虫口密度显著高于露地。烟粉虱各虫态均可在各地温室大棚和漳州露地越冬,而在南平和三明等温度较低的地区以卵和伪蛹在露地越冬。在蔬菜上发现越冬烟粉虱有MEAM1隐种和MED隐种,温室大棚中两隐种数量分别为57只和111只,温室大棚可能有助于MED隐种定殖。室内耐寒性测定证实卵和高龄若虫比低龄若虫以及成虫更耐寒,烟粉虱在花椰菜、龙葵和辣子草上的世代存活率分别为83.7%、79.3%和81.6%,世代发育历期分别为18.9 d、16.7 d和18.8 d,龙葵和辣子草是烟粉虱适宜的越冬杂草寄主。综上,烟粉虱可在福建省露地越冬,温室大棚加重了烟粉虱的发生为害。     

Evidence for selection pressure from resistant potato genotypes but not from fungicide application within a clonal Phytophthora infestans population

Insight into pathogen population dynamics provides a key input for effective disease management of the potato late blight pathogen Phytophthora infestans. Phytophthora infestans populations vary from genetically complex to more simple with a few clonal lineages. The presence or absence of certain strains of P. infestans may impact the efficacy of fungicides or host resistance. Current evidence indicates that genetically, the Irish populations of P. infestans are relatively simple with a few clonal lineages. In this study, P. infestans populations were genetically characterized based on samples collected at the national centre for potato breeding during the period 2012–16. The dominance of clonal lineages within this P. infestans population was confirmed and the potential selection pressure of fungicide treatment (2013–15) and host resistance (2016) on this clonal P. infestans population was then investigated. It was found that fungicide products did not notably affect the genetic structure of sampled populations relative to samples from untreated control plants. In contrast, samples taken from several resistant potato genotypes were found to be more often of the EU_13_A2 lineage than those taken from control King Edward plants or potato genotypes with low resistance ratings. Resistant potato varieties Sarpo Mira and Bionica, containing characterized R genes, were found to strongly select for EU_13_A2 strains.     

适度饥饿浅黄恩蚜小蜂对烟粉虱和温室白粉虱的寄生和取食选择

为评价释放前经历饥饿对浅黄恩蚜小蜂Encarsia sophia(GiraultDodd)寄生取食粉虱能力的影响,以3龄Q隐种烟粉虱Bemisia tabaci Q和温室白粉虱Trialeurodes vaporariorum若虫为寄主,在2种粉虱单独或同时存在的情况下,比较释放前经适度饥饿、初羽化未饥饿和初羽化喂饲蜂蜜水3种处理的浅黄恩蚜小蜂对2种粉虱寄主的寄生和取食选择情况。结果表明,在2种粉虱单独存在时,经适度饥饿6 h的浅黄恩蚜小蜂寄生的烟粉虱和温室白粉虱显著多于其它处理,而且能取食更多的温室白粉虱,经适度饥饿的寄生蜂在24 h内通过寄生和取食杀死烟粉虱和温室白粉虱的总量分别为12.5头和12.9头。在2种粉虱同时存在时,适度饥饿寄生蜂取食2种粉虱的总量明显高于其它处理,但不同处理间无显著差异,适度饥饿寄生蜂通过寄生和取食杀死2种粉虱的数量最多为11.5头,显著高于未饥饿处理的6.5头。表明释放前经历适度饥饿可以明显提高浅黄恩蚜小蜂寄生和取食粉虱若虫的能力。     

Impact of Austropuccinia psidii in New Caledonia,a biodiversity hotspot

Myrtle rust, caused by the fungus Austropuccinia psidii, infects a wide range of host species within the Myrtaceae family worldwide. Since its first report in 2013 from New Caledonia, the extent of the host range, geographical distribution and genetic diversity of A. psidii in this territory have been unknown. This study reports 67 new host species distributed in 13 different Myrtaceae genera, including five new genera. The pathogen was found in various types of plant communities, where Myrtaceae species are the dominant or codominant species, as well as in several nurseries. It is now considered a significant threat to the biodiversity of ecosystems and the Myrtaceae‐related economy. A 3‐year disease monitoring trial with 35 cultivated Myrtaceae species showed variations in disease severity at the species and individual scales. This suggests that some level of genetic resistance to myrtle rust may possibly exist among the endemic Myrtaceae of New Caledonia. A population genetic investigation revealed that only one single genotype of A. psidii occurs across its entire host range in New Caledonia. Therefore, it is essential to carry out population genetic surveillance to identify the appearance of mutations or the introduction of potentially more virulent genotypes of A. psidii. The outcomes from this study will assist with the ongoing management of the disease in New Caledonia.     

非洲猪瘟流行病学研究进展

非洲猪瘟(African swine fever,ASF)主要在非洲大陆流行,它通过偶然机会侵入到欧洲和美洲,之后进一步侵袭到了东欧和高加索地区,且到目前也未完全控制。非洲猪瘟病毒(African swine fever virus,ASFV)可通过软蜱传播,感染野猪和家猪,其在特定生态系统中的生存能力由它所在的野生宿主种群和畜牧生产系统来界定。ASF是可导致家猪和野猪死亡率极高的病毒性疾病,且因缺少有效的疫苗和治疗方法而造成巨大的经济损失。除了预防和扑杀,暂无其他更好的应对方法,所以需要很好地了解ASF流行病学,预防和控制其传播,以便实施更多有针对性的措施。     

Genetic and phenotypic characterization of Botrytis calthae

Botrytis calthae is a necrotrophic plant pathogen, closely related to the ubiquitous broad host range fungus Botrytis cinerea, but highly host specific. Botrytis isolates from lesions of Caltha palustris grown at different locations were classified with genetic markers as either B. calthae or Botrytis pseudocinerea, or less frequently as B. cinerea. A PCR‐based identification of B. calthae was developed. Seven haplotypes of B. calthae could be distinguished. Compared to B. cinerea, mycelium growth of B. calthae was similar, but conidiation less abundant, and sclerotia formation was only partially repressed by light. Conidia of B. calthae germinated more slowly, and showed a highly acidic optimum (pH 2·5) compared to B. cinerea conidia (pH 5·3). All B. calthae isolates were sensitive to common anti‐Botrytis fungicides, but showed partial resistance to the succinate dehydrogenase inhibitors boscalid, fluopyram and carboxin. Infection experiments revealed a weak capability of B. calthae to induce necrotic lesions on plants that are hosts for B. cinerea. On C. palustris leaves, B. calthae induced similar lesions to B. cinerea. These data provide a basis for comparative molecular investigation of the physiology and host specificity of B. calthae and closely related Botrytis species.     

A yellows disease system with differing principal host plants for the obligatory pathogen and its vector

A stolbur‐type phytoplasma is the putative pathogen of grapevine yellows disease that causes economic damage to vineyards in most growing areas around the world. The pathogen is known to be transmitted to vines by two planthoppers, Hyalesthes obsoletus and Reptalus panzer; the latter is found in Europe but has not yet been observed in Israel. The establishment of a vector–pathogen–plant relationship requires that the pathogen and the vector meet on a shared host plant. This does not happen in the ecosystem examined here, where two different principal host plants for the obligate pathogen and its vector exist: the pathogen is established on vines, while its vector, H. obsoletus, develops on Vitex agnus‐castus. The present study verified that: (i) the vector cannot complete its life cycle on vines; (ii) V. agnus‐castus does not grow in the immediate vicinity of vines, and does not harbour the pathogen; and (iii) the pathogen is not vertically transmitted from mother to offspring. Moreover, in a thorough search of plants in vine growing areas, no other plants were found that host both the vector and the pathogen. However, it was found that the planthopper can acquire the phytoplasma from infected vines. Nonetheless, this does not prove the ability of the planthopper to further transmit the pathogen to vines and does not explain the presence of the vector on the non‐preferred vines. Thus, the enigma of the pathogen–vector–host triangle in this system remains unresolved.