Radiation of pollination systems in the Iridaceae of sub-Saharan Africa

BACKGROUND: Seventeen distinct pollination systems are known for genera of sub-Saharan African Iridaceae and recurrent shifts in pollination system have evolved in those with ten or more species. Pollination by long-tongued anthophorine bees foraging for nectar and coincidentally acquiring pollen on some part of their bodies is the inferred ancestral pollination strategy for most genera of the large subfamilies Iridoideae and Crocoideae and may be ancestral for the latter. Derived strategies include pollination by long-proboscid flies, large butterflies, night-flying hovering and settling moths, hopliine beetles and sunbirds. Bee pollination is diverse, with active pollen collection by female bees occurring in several genera, vibratile systems in a few and non-volatile oil as a reward in one species. Long-proboscid fly pollination, which is apparently restricted to southern Africa, includes four separate syndromes using different sets of flies and plant species in different parts of the subcontinent. Small numbers of species use bibionid flies, short-proboscid flies or wasps for their pollination; only about 2 % of species use multiple pollinators and can be described as generalists. SCOPE: Using pollination observations for 375 species and based on repeated patterns of floral attractants and rewards, we infer pollination mechanisms for an additional 610 species. Matching pollination system to phylogeny or what is known about species relationships based on shared derived features, we infer repeated shifts in pollination system in some genera, as frequently as one shift for every five or six species of southern African Babiana or Gladiolus. Specialized systems using pollinators of one pollination group, or even a single pollinator species are the rule in the family. Shifts in pollination system are more frequent in genera of Crocoideae that have bilaterally symmetric flowers and a perianth tube, features that promote adaptive radiation by facilitating precise shifts in pollen placement, in conjunction with changes in flower colour, scent and tube length. CONCLUSIONS: Diversity of pollination systems explains in part the huge species diversity of Iridaceae in sub-Saharan Africa, and permits species packing locally. Pollination shifts are, however, seen as playing a secondary role in speciation by promoting reproductive isolation in peripheral, ecologically distinct populations in areas of diverse topography, climate and soils. Pollination of Iridaceae in Eurasia and the New World, where the family is also well represented, is poorly studied but appears less diverse, although pollination by both pollen- and oil-collecting bees is frequent and bird pollination rare.     

Host feeding in insect parasitoids: why destructively feed upon a host that excretes an alternative?

Host feeding is the consumption of host tissue by the adult female parasitoid. We studied the function of destructive host feeding and its advantage over non‐destructive feeding on host‐derived honeydew in the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae). We allowed parasitoids to oviposit until they attempted to host feed. We either prevented or allowed host feeding. Parasitoids had access to sucrose solution, with or without additional access to honeydew. Parasitoids that were allowed to host feed did not have a higher egg load 20 or 48 h after host feeding than parasitoids prevented from host feeding. Host feeding did not increase the number of eggs matured within these periods, nor did the time spent host feeding positively affect any of these response variables. On the other hand, the presence of honeydew did have a positive effect on egg load 20 and 48 h after host feeding compared with parasitoids deprived of honeydew. Parasitoids with access to honeydew matured more eggs within these periods than honeydew‐deprived parasitoids. Host feeding increased life expectancy, but this effect was nullified when honeydew was supplied after the host‐feeding attempt. In conclusion, feeding on honeydew could be an advantageous alternative to host feeding in terms of egg quantity and longevity. This applies especially to parasitoids exploiting Homoptera, because these parasitoids can obtain honeydew from the host itself. It is possible that destructive host feeding has evolved to enable females to sustain the production of high‐quality anhydropic eggs, which may be important in the parasitoid's natural environment. We argue that future studies should take natural alternative food sources into more consideration.     

The influence of temperature on size as an indicator of host quality for the development of a solitary koinobiont parasitoid

The influence of aphid size on the host quality assessment and progeny performance of aphidiine parasitoids was examined using the mealy plum aphid parasitoid, Aphidius transcaspicus Telenga (Hymenoptera: Braconidae) and the black bean aphid, Aphis fabae Scopoli (Homoptera: Aphididae), as a readily acceptable alternate host. Aphid size in relation to stage of development was manipulated by rearing synchronous aphid cohorts at either 15 or 30 °C. At 15 °C, 2nd instar aphids were approximately the same size as 4th instar aphids reared at 30 °C. Cohorts of 30 aphids from each instar, reared at each temperature, were exposed to parasitism by a single parasitoid female for a period of 5 h. Overall susceptibility to parasitism did not vary between aphid cohorts, but the parasitoid response to aphid size differed significantly between rearing temperatures for both progeny sex ratio (parent female assessment of host quality) and larval growth and development (host suitability for parasitoid development). For aphids reared at 15 °C, the proportion of female progeny and emerging adult size for the parasitoid increased linearly with aphid size at the time of attack, while development time remained constant. In contrast, for aphids reared at 30 °C, the proportion of female progeny, emerging adult size, and the development time of the parasitoid all declined with aphid size at the time of attack. The contrasting responses of the parasitoid to host size for aphids reared at the two temperatures suggest that host quality is only indirectly related to aphid size among aphidiine parasitoids. The possible effects of higher temperatures on nutritional stress, obligate endosymbionts, and future growth potential of the aphids are discussed as explanations for the variation in host quality for parasitoid development.     

Evidence for widespread cryptic sexual generations in apparently purely asexual Andricus gallwasps

Oak gallwasps (Hymenoptera, Cynipidae, Cynipini) are one of seven major animal taxa that commonly reproduce by cyclical parthenogenesis (CP). A major question in research on CP taxa is the frequency with which lineages lose their sexual generations, and diversify as purely asexual radiations. Most oak gallwasp species are only known from an asexual generation, and secondary loss of sex has been conclusively demonstrated in several species, particularly members of the holarctic genus Andricus. This raises the possibility of widespread secondary loss of sex in the Cynipini, and of diversification within purely parthenogenetic lineages. We use two approaches based on analyses of allele frequency data to test for cryptic sexual generations in eight apparently asexual European species distributed through a major western palaearctic lineage of the gallwasp genus Andricus. All species showing adequate levels of polymorphism (7/8) showed signatures of sex compatible with cyclical parthenogenesis. We also use DNA sequence data to test the hypothesis that ignorance of these sexual generations (despite extensive study on this group) results from failure to discriminate among known but morphologically indistinguishable sexual generations. This hypothesis is supported: 35 sequences attributed by leading cynipid taxonomists to a single sexual adult morphospecies, Andricus burgundus, were found to represent the sexual generations of at least six Andricus species. We confirm cryptic sexual generations in a total of 11 Andricus species, suggesting that secondary loss of sex is rare in Andricus.     

基于28S rDNA D2基因序列的几种寄生夜蛾科的多胚跳小蜂的分子系统发育（英文）

本文基于28S rDNA D2部分序列, 用MP和ML方法对几种寄生夜蛾科的多胚跳小蜂Copidosoma spp.进行了系统发育研究,并对其形态和生物学关系进行了讨论。结果表明：寄生金翅夜蛾亚科(Plusiinae)的C. floridanum 和寄生实夜蛾亚科(Heliothinae)的C. primulum关系较近,而以夜蛾亚科(Noctuinae)为寄主的C. truncatellum 和 C. agrotis关系更近。结果提示核基因28S D2区可能对研究多胚跳小蜂种间的系统发育关系很有帮助。     

中国湖南切叶蚁属一新种(膜翅目,蚁科)

描述中国湖南省切叶蚁属Myrmecina Curtis 1新种,即少节切叶蚁M.pauca sp.nov.。新种与食草切叶蚁M.graminicola(Latreille)相似,但触角只有11节,柄节基部圆柱形,并腹胸背面及侧面纵皱纹明显较粗,背面中央有1条宽的纵沟贯穿全长。目前世界切叶蚁属所有已知种类的触角均为12节,但新种的触角只有11节,所以很容易与同属的所有种类相区别。正模工蚁,湖南省桂东县八面山自然保护区,2004-06-14,黄建华采。副模:3工蚁,与正模同巢采集;1工蚁,湖南省江永县源口自然保护区,2003-09-23,黄建华采;1工蚁,湖南省炎陵县桃源洞自然保护区,2003-09-24,黄建华采;1雌蚁,湖南省衡阳市衡山自然保护区,2003-09-08,黄建华采;1雌蚁,湖南省望城县黑麋峰森林公园,2003-09-12,黄建华采;1雌蚁,湖南省通道县木脚乡宏门冲自然保护区,2004-07-25,黄建华采。词源:新种以拉丁词"paucus"(少)命名,以显示其"触角节数比该属其它已知种少"这一重要鉴别特征。     

中国茧蜂亚科一新属一新种(膜翅目,茧蜂科)

记述茧蜂亚科1新属1新种,即阔鞘茧蜂属Platybracon gen.nov.和中华阔鞘茧蜂 Platybracon sinicus sp.nov..文中对新属及新种进行了详细的描述,并附有鉴别形态特征图,新属与其近似属作了比较.模式标本存放于福建农林大学益虫研究室.     

中国三节叶蜂属一新种(膜翅目,三节叶蜂科)

记述采自中国辽宁的三节叶蜂科1新种:Arge reversinervis sp.nov.。新种隶属于三节叶蜂属rustica-metallica种团,并与分布于日本的Arge abelivora Okutani近似,但新种触角亚端部强烈膨大,腹部和后足股节全部黑色,腹部背板具明显的微细刻纹,后足胫节基部4/5黄白色,各足基跗节大部浅褐色,OOL∶POL∶OCL=18∶11∶8 ,前翅C脉背侧大部暗褐色,R M脉几乎等长于Rs脉第1段, 2Rs室上缘显著短于下缘。新种后头强烈膨大,前翅2Rs室上缘显著短于下缘,腹部背板具明显刻纹,颜面具中纵脊,体具铜色光泽,可与同属已知各种鉴别。模式标本保存于中南林业科技大学模式昆虫标本室。     

四突跳小蜂亚科中国新纪录属、种(膜翅目,跳小蜂科)

记述了四突跳小蜂亚科中国1新纪录属,阿纳跳小蜂属Anagyrietta Ferrière,及中国2新纪录种,豹纹阿纳跳小蜂Anagyrietta pantherina Ferrière和宽柄杜丝跳小蜂Dusmetia euripersiae Trjapitzin,并给出了其形态特征图。研究标本研究标本保存在中国科学院动物研究所动物标本馆。