Quantitative trait loci for resistance to herbivores in willow: field experiments with varying soils and climates

As a basis for genetic improvement of willow (Salix spp.) for use in wood biomass production, quantitative trait loci (QTLs) responsible for resistance to herbivores have been identified in a tetraploid hybrid F₂ population originating from a cross between Salix dasyclados (Wimm.) and Salix viminalis (L.) (Salicaceae). Symptoms of herbivory, caused by various insects and game, and, in addition, leaf rust, were assessed in three field locations with varying soils and climates. Eleven damage traits (lost leaf area, leaf discoloration, leaf blisters, leaf‐mite symptoms, leaf‐margin cuts, and various estimates of shoot‐tip damage by a gall midge, game, and lepidopterans) were submitted to QTL analysis. A composite interval mapping approach was used to estimate the number of QTLs, the magnitude of the QTLs, and their position on genetic linkage maps. Most of the identified QTLs were specific for each trait and location, but a few QTLs common across the locations were also detected. Each QTL explained between 8 and 24% of the phenotypic variation, depending on damage trait and field location. Clusters of QTLs for different traits were found at several linkage groups, indicating either a common genetic base or tightly linked QTL. Our results emphasize the need for verification of QTL studies over different environments.     

中国瘿蚊科一新记录属及一新种(双翅目)

本文记述采自中国浙江省为害柿树的瘿蚊１新种：柿伪安瘿蚊ＰｓｅｕｄａｓｐｈｏｎｄｙｌｉａｄｉｏｓｐｙｒｉＭｏｅｔＸｕ,ｓｐ．ｎ．。模式标本存放于山东农业大学昆虫标本室。     

A female sex-pheromone in the pea midge, Contarinia pisi

Experiments designed to demonstrate the existence of a female sex-pheromone in the pea midge, Contarinia pisi Winn. (Diptera: Cecidomyiidae) are described. Recordings from antennal receptors of males showed that extract of virgin females elicited an increase in spike activity. Field trapping experiments showed that traps containing virgin females or crude extract of virgin females caught large numbers of males.

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Résumé L'antenne des mâles de Contarinia pisi répond par électro-antennogramme à un courant d'air contaminé par des femelles vierges. Des pièges contenant des femelles attirent de nombreux mâles.

     

簇瘿蚊属分类学研究及一新种记述(双翅目,瘿蚊科)

对簇瘿蚊属Acinacistyla Fedotova&Sidorenko的属征进行修订,编写该属世界分种检索表(雄性),并记述采自贵州、云南、江西和河南四省的该属1新种,命名为短瓣簇瘿蚊Acinacistyla brevilobata sp.Jiao et Bu,nov.,模式标本保存在南开大学昆虫标本馆.短瓣簇瘿蚊,新种Acinacistyla brevilobata Jiao et Bu,sp.nov.(图1～10)新种与分布于俄罗斯的柔毛簇瘿蚊Adnadstyla papposFedotova&Sidorenko在雄成虫外生殖节的抱器基节中基瓣及肛下板等特征相似,但区别明显:1)新种肛下板近端部两侧各着生1个约为肛下板长度l/3的端瓣,且该瓣不具关节状结构,而A.papposa肛下板近端部两侧各着生1个约与肛下板等长、在近基部1/3处具关节状结构的端瓣;2)新种抱器基节中基瓣的较长亚瓣卷曲并缠绕于阳茎;而A.p嘞posa抱器基节中基瓣的较长亚瓣长棍状直立、且并不卷曲缠绕.正模♂,贵州梵净山护国寺(27.5°N,108.4°E;海拔1 350 m),2002-05-28 ～ 29,王新谱马氏网捕.副模:1 ♂,贵州道真县大沙河仙女洞(29.32°N,107.40°E;海拔600m),2004-05-24,朱卫兵马氏网捕;1♂,云南腾冲整顶(25.01°N,98.30°E;海拔1 800m),2002-09-03 ～ 05,薛怀君马氏网捕;4♂♂,云南泸水姚家坪(25.59°N,98.49°E;海拔2 450 m),2002-09-16 ～18,薛怀君马氏网捕;2♂♂,江西井冈山小溪洞(26.28°N,114.14°E;海拔220m),2002-07-23～27,薛怀君马氏网捕;2♂♂,江西宜丰官山保护区东河站(27.07°N,114.09°E;海拔1 000m),2002-07-29 ～08-01,薛怀君马氏网捕;1♂,河南栾川龙峪湾鸡角尖(33.66°N,111.75°E;海拔1 600 m),1996-07-13,李军网捕.模式标本保存在南开大学生命科学学院昆虫标本馆.词源:种名brevi~bata为一阴性复合拉丁形容词,意为“短瓣的”,指该种肛下板近端部两侧各着生1个相对于柔毛簇瘿蚊A.apposa较短的瓣.     

Avoidance of occupied hosts by the Hessian fly: oviposition behaviour and consequences for larval survival

Abstract 1. Unoccupied wheat plants and wheat plants occupied by conspecific eggs or larvae were presented to ovipositing female Hessian flies in choice tests.
2. The presence of conspecific eggs on the leaf surfaces of wheat plants did not appear to have any effect on the responses of ovipositing Hessian fly females.
3. The presence of conspecific larvae at the base and nodes of wheat plants for 1, 6, or 11 days had significant effects on Hessian fly oviposition. Eggs oviposited on plants were inversely proportional to larval densities and days of larval occupation.
4. Feeding by Hessian fly larvae is associated with several changes in wheat plants. One of these changes, the growth arrestment of the plant, was measured by recording the heights of plants used in oviposition tests. Plant heights were inversely proportional to both larval densities and days of occupation. Plant heights were directly proportional to eggs oviposited on plants.
5. The consequences of adult female avoidance of plants occupied by conspecific larvae were investigated by allowing females to oviposit on unoccupied plants and 1-day, 6-day, and 11-day larval occupied plants, then scoring at the end of the first larval instar the survival of the offspring that resulted from this oviposition.
6. Survival during the first larval instar was 88% for the offspring of females that oviposited on unoccupied plants, decreasing to 82, 31, and 4% on the 1-day, 6-day, and 11-day occupied plant treatments. On these four plant treatments, a positive correlation was found between larval performance (i.e. survival) and the preferences of ovipositing females.
7. On the four plant treatments, relationships between first-instar larval density and first-instar larval survival varied significantly. On unoccupied plants, survival was inversely proportional to density. On plants oviposited on at 6 days of larval occupation, survival was directly proportional to density.     

中国异瘿蚊属分类研究(双翅目:瘿蚊科)

记述了中国瘿蚊科1新纪录属异瘿蚊属及一新种：横瓣异瘿蚊Heterogenella transversa.spn.nov.,模式产地云南中甸虎跳峡;中国3新纪录种;达氏异瘿蚊H.dolini Berest(四川理县米亚罗）,短须异瘿蚊H.hybrida Mamaev(内蒙古额尔古纳旗莫尔道嘎）和纵缝异瘿蚊H.linearis Yukawa(云南丽江玉龙山）。文中给出了异瘿蚊属中国已知种类分种检索表。模式标本保存于南开大学生物系昆虫标本室。     

Patterns of interspecific associations of stem gallers on willows

Abstract.  The pattern of interspecific associations of three stem-galling sawfly species ( Euura atra , E. elaeagnos , E. purpureae ) and three stem-galling gallmidge species ( Rabdophaga sp. 3–5) was investigated on five willow taxa ( Salix alba , S. fragilis , S.  ×  rubens , S. elaeagnos , S. purpurea ) at five natural sites in Central Europe. The willow species harboured specific species associations of two stem gallers, each pair consisting of one Euura and one Rabdophaga species. The stem gallers were patchily distributed and their densities varied significantly among willow host plant species, host plant individuals, and host plant sexes. Four of the six species showed a significant increase in galling rate with shoot length. The other two species were the sawfly and cecidomyiid pair that induce galls on S. purpurea . The preference of stem gallers to longer shoots was generally not related to higher larval performance in terms of survival. Only one species, Rabdophaga sp. 5, was found to be more abundant on male plants. The correlation of densities of the species pairs of stem gallers was independent of willow sexes. Species pairs of stem gallers co-occurring on the same willow species tended to attack different shoots within the same host plant individual. When species pairs co-occurred on shoots they were usually found in similar densities as when occurring alone on shoots. The stem-galling sawflies usually formed galls at the basal part of a shoot, whereas the gallmidge R . sp. 5 ( R . sp. 3 and R . sp. 4 showed no clear tendency) preferred the middle or distal part of a shoot. This is interpreted with differences of their phenology and oviposition period.     

Timing of growth determines fitness and performance of a galling insect on willow

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Determinants of assemblage size for the parasitoids of Cecidomyiidae (Diptera)

Summary The parasitoids known to attack 191 phytophagous species of gall midges (Cecidomyiidae) were used to examine factors influencing parasitoid assemblage size. The number of parasitoid species a midge species supports was tested against nine variables describing geographical, biological and ecological attributes of hosts. The apparency of midge larvae was found to have the greatest influence on parasitoid assemblage size; highly visible species support more parasitoids than less visible ones. Pupation site and midge voltinism also significantly affect associated parasitoids, at least for highly apparent hosts. Biogeographic region, host-plant architecture and the plant parts infested were found to be of secondary importance. The surface texture of infested plant parts, the number of midge larvae occupying galls and the diversity of plant tissues infested have minimal apparent effects on parasitoid richness. Parasitoid assemblage size and total parasitism rates were also found to be positively correlated for 73 galling and nongalling midge species, and gallers typically suffer higher levels of parasitism than non-gallers. Using these data to test the enemy hypothesis, which proposes that the galling habit has evolved to escape attack from parasitoids, we conclude that parasitoid pressure cannot account for the presence of galls in the Cecidomyiidae.