In a world of white,flower colour matters: A white–purple transition signals lack of reward in an alpine Euphrasia

The New Zealand alpine flora displays a range of unusual characteristics compared with other alpine floras, in particular the high frequency of species with small white flowers. The presence of both white and bright purple flowers on the same plant in the New Zealand alpine annual creeping eyebright (Euphrasia dyeri Wettst.) provides an ideal opportunity to investigate the significance of flower colour in an environment where coloured flowers are rare. The relationships among flower age, gender phase, reward availability and petal colour were assessed in natural populations of E. dyeri. The effect of pollination on flower colour was tested using hand pollination of bagged flowers. Direct observations and videos of flowers were used to assess patterns of flower visitation by native and introduced pollinators. Unpollinated white E. dyeri flowers changed from white to purple within 6 days. However, pollination of white flowers triggered a significantly faster colour change, typically within 1–2 days. White flowers had receptive stigmas, large amounts of lipid‐rich pollen and small amounts of nectar, whereas stigmas of purple flowers are not receptive and flowers did not provide pollen or nectar rewards. Flowers were mainly visited by native syrphid flies. Both native syrphids and introduced Bombus bees showed a marked avoidance of purple flowers, tending to preferentially visit white flowers. Our study suggests that flower colour change from white to bright purple in E. dyeri functions to direct pollinators to rewarding, receptive flowers. As many Euphrasia L. species are described as having variably coloured flowers, this mechanism may be more widespread in the genus. Furthermore, our results add to the growing evidence that the dominance of white flowers in the New Zealand alpine is not simply due to a lack of colour discrimination among pollinators.     

中国裸眼蚜蝇属研究(双翅目,蚜蝇科)(英文)

记录中国裸眼蚜蝇属Citrogramma 11种 (包括1新种)。文中给出黄色裸眼蚜蝇C. amarilla、阿里山裸眼蚜蝇C.arisanicum、黑腿裸眼蚜蝇C. citrinoides、柑桔裸眼蚜蝇C.citrinum、卡氏裸眼蚜蝇C. currani、吉德裸眼蚜蝇C. gedehanum及新种西藏裸眼蚜蝇Citrogramma xizangensis sp. nov.等种的异名录、形态描述、特征图及分布,研究标本保存于陕西理工学院动植物标本馆。清丽裸眼蚜蝇C. clarum、褐翅裸眼蚜蝇C. fumipenne、松村裸眼蚜蝇C. matsumurai、素木裸眼蚜蝇C.shirakii等作者未见标本,文中仅列出异名录及分布。西藏裸眼蚜蝇,新种Citrogramma xizangensis sp. nov. (图36～41)体长:♂10mm,♀11mm;翅长:♂8mm,♀9mm。本种近似Citrogramma amarilla Mengual,两者颜黄色,后胸腹板具毛,胸部侧板黄色,翅透明,翅膜具微刺,腹部黄色带伸达背板侧缘,但新种雄性前足腿节后腹侧具1列黑色长毛,后者前、中足腿节主要具黑毛,仅基部具黄毛;新种雌性第2背板具1对狭长黄斑,后者第2背板具横带。正模1♂,西藏林芝,2008-09-26,潘朝晖采。副模:1♀,西藏林芝,2008-09-26,潘朝晖采;1♂,西藏林芝,2008-09-24,潘朝晖采。词源:新种种名源自模式产地。     

中国长白山地区鼻颜蚜蝇属一新种记述(双翅目,食蚜蝇科)

记述采自吉林省长白山地区的鼻颜蚜蝇属1新种,黑盾鼻颜蚜蝇Rhingia nigriscutella sp.nov.,新种近似亮黑鼻颜蚜蝇R.laevigata Loew。但新种第3背板基部具1对近梯形黄色斑,而亮黑鼻颜蚜蝇第3背板整体棕红色,后缘黑色,正中具暗纵条。同时提供其特征图。模式标本保存在东北师范大学生命科学学院标本馆及陕西理工学院动植物标本馆。     

A NEW FOSSIL HOVERFLY (INSECTA, DIPTERA: SYRPHIDAE) FROM THE RANDECK MAAR (EARLY MIOCENE, SOUTH-WEST GERMANY)

Abstract:  Helophilus nothobombus sp. nov. (Diptera: Syrphidae) is described from Early Miocene lake sediments of the Randeck Maar (Swabian Alb, south-west Germany) and compared to other fossil species of the genus. Helophilus primarius Germar, 1837 and Helophilus villeneuvi Théobald, 1937 do not show diagnostic features that allow assignment to the genus Helophilus or even to the tribe Eristalini. Helophilus miocaenicus (Stackelberg, 1925) and H. nothobombus thus are the only plausible fossil species of the genus. The rat-tailed maggots of Helophilus most probably were part of the biocoenosis of the shores of the Randeck Maar lake. The frequency of larvae of Stratiomyidae shows that there were also suitable habitats for species of Helophilus and related genera.     

The key mimetic features of hoverflies through avian eyes

Batesian mimicry occurs when a palatable species (the mimic) gains protection from predators by resembling an unpalatable or otherwise protected species (the model). While some mimetic species resemble their models closely, other species ('imperfect mimics') are thought to bear only a crude likeness. In an earlier study, pigeons (Columba livia) were trained to recognize wasp images in one experiment and non-mimetic (NM) fly images in another by rewarding the pigeons for pecking on the respective image types. These pigeons were subsequently presented with different images, including seemingly wasp-like hoverfly species, and the recorded peck rates on these images were used as a measure of the pigeons' perception of the hoverflies' mimetic similarity. To identify a candidate set of morphological features that the pigeons used when assessing this mimetic similarity, we first extracted a range of biometrical measurements from images originally presented to the pigeons. We then repeatedly optimized an empirical model in an attempt to match the recorded pigeon peck rates while using as few biometrical features as input as possible. Our models were able to fit the pigeon peck rates with considerable accuracy even while excluding many input features. Antennal length, a feature commonly used to discriminate between flies and wasps, was regularly retained as an input variable, but overall a different set of biometrical features was important for predicting the peck rates of pigeons rewarded for identifying wasps compared to those rewarded for identifying NM flies. In highlighting the importance of specific biometrical features in promoting mimicry and the irrelevance of others, our optimized models provide an explanation as to why certain species that appear to be poor mimics to humans are judged to be good mimics by birds.     

中国蜂蚜蝇属一新种记述(食蚜蝇科,蜂蚜蝇族)

记述采自中国宁夏回族自治区六盘山自然保护区蜂蚜蝇属1新种:六盘山蜂蚜蝇Volucdla livpanshanensis sp. nov..新种近似Volucella thompsoni Choi et al.,2006.新种雄性复眼接缝长,约等于额长,腹部第3背板前缘具狭横斑,第4背板后缘向前凹入,使生殖后节背面可见;雌性复眼被毛极稀疏,腹部第3背板前缘具黄白色狭横带.模式标本保存于陕西理工学院动植物标本馆.黑蜂蚜蝇V.nigricans和黄盾蜂蚜蝇V.pellucens tabanoides为宁夏首次记录.文中给出新种描述、特征图和种团分类检索表.     

Determination of phylogenetic position of Pipizini (Diptera: Syrphidae): based on molecular biological and morphological data

Based on the sequence analysis of 5.8S subunit and internal transcribed spacers (ITS ) of ribosomal RNA gene (rDNA), the molecular phylogenetic tree of representative species of Pipizini and three groups of Syrphidae with different feeding habits (seven species belong to six genera) was constructed. Meanwhile, the phylogenetic tree of tribes (including Pipizini and other 17 tribes of Syrphidae) was constructed using morphological characteristics of adults and larvae and the number of chromosomes. Both the results show that the relationship between Pipizini and predatory groups is closer than that between Pipizini and saprophagous groups. So it is suggested that Pipizini be transferred from Milesiinae to Syrphinae.     

Searching behaviour in relation to starvation of Syrphus ribesii

The searching mechanisms of Syrphus ribesii (L.) larvae were examined in relation to degree of starvation. Satiated larvae remained close to aphids when not feeding probably due to reduced speeds of locomotion and thigmokinesis. The locomotory mechanisms used by 24-h starved larvae resulted in a concentrated searching pattern whereas those of 48-h starved larvae produced a higher level of dispersion. The role of these differences in the searching process of this predator is discussed.

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Comportement de prospection en fonction du jeûne chez Syrphus ribesii (L.) (Diptera, Syrphidae)

Résumé Le comportement de prospection en fonction de l'importance du jeûne a été examiné chez des larves de Syrphus ribesii L. Les larves rassasiées présentaient une faible vitesse de déplacements frontaux et étaient thigmocinétiques, si bien qu'elles restaient, en absence d'alimentation, près de la proie. Après 24 h de jeûne, elles présentaient un taux de projection (séquence précédant la capture de pucerons) et une vitesse plus élevés, et elles n'étaient plus thigmocinétiques. Les projections étaient distribuées au hasard au cours du chemin prospecté, et il y avait un taux de déviations élevé en présence d'obstacles, comme des hordes de femelles, au lieu de passer outre. Ces résponses produisaient un faible niveau de dispersion et une prospection de type concentré. Toutefois après 48 h de jeûne, les larves avaient le taux de projection et la vitesse les plus élevés. Leurs projections étaient groupées le long du chemin parcouru et le taux de déviation était bas. Le résultat en était un niveau élevé de dispersion.

     

Episyrphus balteatus as a predator of the aphidSitobion avenae on winter wheat

Rates of development ofEpisyrphus balteatus (Diptera: Syrphidae) indicate that three generations are possible during the season. Only one develops in the wheat crop. Feeding activity is highest during the night. Functional response curves for newly hatched larvae, 1 and 5 day-old larvae were determined. The high rate of reproduction and the short feeding period makeE. balteatus an excellent exploiter of a temporary habitat: a cereal aphid colony.

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Episyrphus balteatus (Syrphidae), prédateur deSitobion aveane (Aphididae) sur blé d'hiver

Résumé Les durées de développement deE. balteatus dépendent de la température. L'incubation a duré 14.2 jours à 7.5°C et 1.59 jour à 25°C. Le développement larvaire jusqu'à la dernière défécation a demandé 35.8 jours à 7.5°C, et 10.1 jours à 20°C. Seule une génération peut se développer chaque année sur blé d'hiver, car la durée totale de l'ontogenèse, dans les conditions de température des champs, est comprise entre 30 et 45 jours. Les larves s'alimentent surtout la nuit. La prédation maximale à 20°C augmente avec l'âge de la larve, depuis 2.34 pucerons du troisième stade par jour pour une larve de syrphe néonate jusqu'à 5.04 pucerons du troisième stade quand les larves ont un jour. Les consommations les plus élevées, de 38.6 et 42.7 pucerons par nuit de 7 heures, ont été obtenues avec des larves de 4 à 5 jours, élevées à 21/13°C.A 20°C, le temps consacré à l'alimentation par des larves néonates de syrphes augmente avec la taille de la proie; il passe de 63.6 min pour des pucerons du premier stade à 131.2 min pour ceux du second stade. La relation entre le poids de la larve et le nombre de pucerons consommés est linéaire.E. balteatus a besoin, pour son développement, de moins deS. avenae que deA. fabae.

     

中国墨管蚜蝇属种类及新种记述：双翅目：食蚜蝇科

本文描这蚜蝇属Ｍｅｓｅｍｂｒｉｕｓ Ｒｏｎｄａｎｉ２新种：钩叶墨管蚜蝇Ｍｅｓｍｂｒｉｕｓ ａｄｕｎｃａｔｕｓ Ｌｉ和海南墨管蚜蝇Ｍ．ｈａｉｎａｎｅｎｓｉｓ Ｌｉ,１中国新记录和黑墨管蚜蝇Ｍ．ｎｉｇｅｒ Ｓｈｉｒａｋｉ．并给出该属中国已知各类的检索表及其分布．新种模式标本 保存于华南农业大学昆虫标本室。