Occurrence and impact of Agrilus spp. and associated egg parasitoids in hazel groves of Northwest Italy

In several hazel (Corylus avellana L.) groves in the area of Langhe (Piedmont, Northwest Italy), many hazel branches suddenly withered, and in some cases, the whole tree died, with heavy economic losses for the farmers. Symptoms of jewel beetle attacks were detected on the trees. Eight Agrilus species were caught by traps from 2007 to 2009 in the surveyed hazel groves; among them, only four species have been known to develop on hazel. On the traps, Agrilus olivicolor Kiesenwetter was the most abundant species, while almost only Agrilus viridis (L.) was sampled by plant beating from 2008 to 2010. Moreover, almost all adults emerged from field‐collected hazel wood belonged to this latter species that proved to be the main responsible for the severe attacks on the hazel trees. Agrilus viridis adults emerged from late May to late June, and generally lived until the end of August, while egg masses were observed from late May to late July. The egg parasitoid Oobius zahaikevitshi Trjapitzin was found in all of the investigated groves; adults emerged already from the first egg masses collected on hazel trees in late May‐early June. O. zahaikevitshi was able to largely reduce A. viridis populations, with a parasitism rate of more than 50% in some groves. Recent attacks of A. viridis were related to a long period of drought; however, appropriate agronomic practices to minimize the effects of water stress and to conserve natural enemies, such as O. zahaikevitshi, could be more effective to protect hazel groves against boring beetle attacks.     

花曲柳窄吉丁的空间分布

2004年4月~9月,在天津市大港区官港森林公园对花曲柳窄吉丁Agrilus planipennis的空间分布和垂直分布进行了调查研究,应用扩散系数(C)等6种指数法分析测定,确定了该虫在林地中的空间分布呈聚集分布,分布的基本成分是个体群。扩散蔓延规律为聚集型扩散。花曲柳窄吉丁幼虫在树干的垂直分布主要区间在50~150 cm之间。对幼虫垂直分布与树干高度的关系进行分析,其符合立方曲线,曲线方程为:Y=-5.142 9+17.943 7X+21.662 3X2-14.545X3;相关系数R2=0.915,P=0.013。     

Agrilus mali Matsumara (Coleoptera: Buprestidae), a new invasive pest of wild apple in western China: DNA barcoding and life cycle

Agrilus mali Matsumara (Coleoptera: Buprestidae) is a wood‐boring beetle distributed to eastern China that occasionally injures apple species. However, this wood‐boring beetle is new to the wild apple forests (Malus sieversii) of the Tianshan Mountains (western China) and has caused extensive tree mortality. The development of a biological control program for these wild apple forests is a high priority that requires exploration of the life cycle, DNA barcoding and taxonomic status of A. mali. In this study, to determine the diversity of invasive beetles, a fragment of the mitochondrial cytochrome oxidase gene was analyzed. Based on the results, beetles from Gongliu and Xinyuan counties of Xinjiang were identical but differed from those in the apple nursery of Gongliu by a single‐nucleotide substitution. We summarize the taxonomic status, relationships, and genetic distances of A. mali among other Agrilus species using the Tajima‐Nei model in maximum likelihood phylogeny. Analysis revealed that A. mali was closely related to Agrilus mendax and both belong to the Sinuatiagrulus subgenus. The life cycle of A. mali was investigated based on a monthly regular inspection in the wild apple forests of Tianshan. Similar to congeneric species, hosts are injured by larvae of A. mali feeding on phloem tissue, resulting in serpentine galleries constructed between bark and xylem that prevent nutrient transport and leading to tree mortality. Future studies will focus on plant physiological responses to the invasive beetles and include surveys of natural enemies for a potential classical biological control program.     

Native parasitoids and recovery of Spathius agrili from areas of release against emerald ash borer in eastern Tennessee,USA

The parasitoid Spathius agrili Yang, introduced in the USA to suppress populations of the emerald ash borer (EAB), Agrilus planipennis Fairmaire, has been recovered at a release site for the first time in eastern Tennessee after a single year of releases. Other native parasitoids, including Spathius floridanus Ashmead, undetermined species of Spathius (possibly Spathius elegans Matthews and Spathius parvulus Matthews) and Atanycolus cappaerti Marsh & Strazanac, also known to be associated with EAB, were recovered. These recoveries represent the first documentation of these four species, including the introduced S. agrili, associated with EAB in the southern USA. Implications for biological control efforts against EAB are discussed.     

Submergence of black ash logs to control emerald ash borer and preserve wood for American Indian basketmaking

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Effects of the emerald ash borer invasion on the community composition of arthropods associated with ash tree boles in Maryland,U.S.A.

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柑桔爆皮虫卵巢发育动态

本研究利用室内饲养成虫,对柑桔爆皮虫的蛹及正常取食和交配、正常取食但未交配以及正常交配但未取食三种处理的雌成虫的卵巢发育进行了系统观察。结果显示：该虫具有1对卵巢,每侧有5根卵巢管。前两种处理的雌虫卵巢管均能正常发育,成虫寿命在30天左右; 没有取食的雌虫寿命只有7天左右,在其卵巢管的生长区和成熟区均无卵形成。根据卵巢的形状、卵的产生过程、卵巢萼内有无卵粒以及卵黄沉积情况等将卵巢发育程度分为6个级别,即发育初期（0级）、卵黄沉积前期(Ⅰ级)、卵黄沉积期(Ⅱ级)、成熟待产期(Ⅲ级)、产卵盛期(Ⅳ级)和产卵末期(Ⅴ级)。每头雌虫最高怀卵量在140粒左右,根据雌虫怀卵量变化趋势,推测正常取食和交配的柑桔爆皮虫雌虫在出孔后10天左右开始产卵,产卵历期可达22天左右。据此提出该虫卵巢管发育到成熟待产期(Ⅲ级)之前（即羽化出孔后10天之内）为出孔成虫的防治适期。     

Microbial control of Agrilus planipennis (Coleoptera: Buprestidae) with Beauveria bassiana strain GHA: field applications

The effects of Beauveria bassiana strain GHA, applied as BotaniGard ES, on newly colonised and well-established populations of emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae) were evaluated in the field using foliar and trunk sprays in Michigan in 2004–2005. Results from field trials at a newly colonised white ash site showed a 41% reduction in A. planipennis population in fungal-treated trees compared with that of untreated controls. In addition, fungal infection was also found in 20% of the larval population within 14 days of incubation under laboratory conditions. At a site with a well-established Agrilus planipennis population in green ash trees, larval density was reduced by 47% for trees treated with the fungus compared with that of the controls; 21% of larvae from the current generation were found infected after 14 days of laboratory incubation. Fungal-treated green ash trees also produced fewer adults emerging in the next generation, with a 63% reduction in adult density observed in treated trees compared to that of controls. As a result, fungal-treated trees sustained 42% less crown dieback than did controls. A. planipennis larval density was negatively correlated with trunk height above the ground, and positively correlated with log diameter. Results of laboratory leaf bioassays on A. planipennis adults showed that fungal conidia persisted well under field conditions, with mortality of 78–100% at 7 – days post – exposure for leaves collected between 2 and 264 h after application. Potential strategies for using B. bassiana strain GHA for managing A. planipennis are discussed.     

Current status of Agrilus hyperici (Coleoptera: Buprestidae) released in Australia in 1940 for the control of St John's wort: Lessons for insect introductions

The root‐borer Agrilus hyperici was established successfully in Australia in 1940 for the biological control of the weed Hypericum perforatum. It failed to spread widely, however, and surveys in 1980 found that it survived in only one area; near Mudgee in New South Wales. Two isolated populations were found here, both restricted to sheltered creek systems. The distribution of the larger population, at Piambong, was confined to an area of about 10 km². In 1981–82, 76.8% of plants in the core of this area showed damage by larvae to their roots. Although the level of attack was lower than that known from southern Europe, survivorship patterns from larva to adult were similar, confirming A. hyperici to be a ’K‐selected’ insect. The population declined significantly following a severe drought in 1982. Consideration of the early history of their introductions coupled with knowledge of their biologies suggest that strong competition by Chrysolina spp., strongly ‘r‐selected’ insects introduced at the same time, may have restricted the development of A. hyperici. The danger of co‐releasing insects with different life‐history strategies is discussed.     

合欢吉丁Agrilus subrobustus Saunders的学名厘定及危害特性

【目的】本文对危害合欢Albizia julibrissin Durazz的钻蛀性害虫合欢吉丁Agrilus subrobustus Saunders各虫态形态特征及危害特性进行了研究与描述,深入探索其虫道三维结构,以期为合欢吉丁的发生监测及防治提供依据。【方法】查阅相关文献,记述整理了合欢吉丁学名的变化过程,详细地观察并描述了剖腹卵、幼虫、蛹、成虫的形态特征;首次研究总结其坑道系统的各指标特点:虫口密度、坑道长宽、侵入孔特征、蛹室特征、羽化孔特征等,明确了完整虫道的发生发展规律;基于坑道拍照、各向量指标测量,对坑道进行科学手绘,使用Autodesk Maya软件完成合欢吉丁完整虫道的三维重建。【结果】合欢吉丁幼虫细长、乳白色,蛹为裸蛹。成虫铜绿色具金属光泽,观察对比其前胸背板长宽比、盘区和肩前隆脊形态,前胸腹板突形状,鞘翅柔毛分布位置,阳茎形态等特征,结合文献,明确其学名为Agrilus subrobustus Saunders。合欢吉丁主要危害树干韧皮部及木质部,具向阳性;在树皮下钻蛀坑道,侵入孔圆形,不超过1 mm;蛹室米粒状,多位于木质部,少数位于韧皮部;羽化孔"D"型;坑道形状具有规律性,可分为3种:"Z"字型及其变型,密集上下迂回型,椭圆或近半圆型坑道。【结论】基于形态特征的详细描述、学名厘定,有利于合欢吉丁的鉴定及学名的正确使用;完整虫道的复原便于在非成虫期结合寄主种类鉴定害虫种类、评估虫口密度和危害程度,为合欢吉丁的监测提供了具体的判别方法,为化学防治、生物防治等提供参考与技术支持。