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1.
The first example of pollination by fungus gnats in the eudicots is reported. The genus Mitella (Saxifragales) is characteristically produces minute, inconspicuous, mostly dull-coloured flowers with linear, sometimes pinnately branched, petals. To understand the function of these characteristic flowers, we studied the pollination biology of four Mitella species with different floral traits and different sexual expression: dioecious M. acerina , gynodioecious M. furusei var. subramosa , and hermaphroditic M. stylosa var. makinoi and M. integripetala. Flower-bagging experiments showed that wind pollination did not occur in the dioecious and gynodioecious species. Two years of observations of flower visitors at six study sites in Japan revealed that the principal pollinators of all four Mitella were specific species of fungus gnats (Mycetophilidae), which landed on the flowers with their long spiny legs settling on the petals. Characteristically, numerous pollen grains were attached to the fungus gnats in specific locations on the body. Although, on average, 1.3–2.6 fungus gnats visited each inflorescence per day, the fruit set of both bisexual and female flowers exceeded 63%. These results suggest that fungus gnats are highly efficient pollinators of Mitella spp., and that Mitella flowers are morphologically adapted to pollination by fungus gnats.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 449–460.  相似文献   
2.
We studied the physical and temporal isolation of two arthropod guilds interacting with Drosera anglica Huds., a terrestrial carnivorous plant. Flowers are separated from basal trap leaves by a leafless stalk. Since arthropods are potentially employed both as prey and pollinators, we asked whether separation of traps from flowers reduces the frequency with which flower visitors are captured by the leaves. Plants captured prey throughout the season, with peak trapping activity occurring before flowering began. The diverse prey spectrum included at least 109 species in 94 genera in 26 of 37 identified families representing 11 arthropod orders. The most common prey were adult flies of Nematocera, particularly Ceratopogonidae (50%) and Chironomidae (42%). The following taxa were periodically abundant: Acarina, Diptera–Cecidomyiidae, Chloropidae, Sciaridae, Hemiptera nymphs and Thysanoptera–Thripidae. Flies (Diptera) were chief flower visitors (95%), dominated by Syrphidae (66%), Bombyliidae and Muscidae (10% each), Calliphoridae (7%), Tachinidae and Dolichopodidae (3% each). Additionally, visitors were a bee (Hymenoptera–Halictidae) and thrips (Thysanoptera–Thripidae). Four families were common to both guilds: Diptera–Dolichopodidae, Muscidae, Tachinidae; and Thysanoptera–Thripidae. However, direct comparisons of identified taxa within these families showed that overlap between flower visitors and prey occurred for Thrips sp. larvae alone, which comprised only 3% of all flower visitors and 0.5% of prey. Drosera anglica exploits distinct guilds of insects for pollinators and prey.  相似文献   
3.
Insect emergence was studied with floating box traps in the littoral of Lake Mindelsee from July 1st until September 30th, 1984. The material was collected every 48 h. Out of the total catch of 6897 specimens per m2, 75.1 % belonged to the Chironomidae, 4,9% to the Chaoboridae, 15,4% to the Ephemeroptera and 3,2% to the Trichoptera. Endochironomus sp., Lauterborniella agrayloides, Polypedilum pullum (Chironomidae) and Oocetis testacea (Trichoptera) are reported for the first time from Lake Mindelsee. The seasonal course of the total emergence showed two distinct peaks: one at the end of July, the other at the beginning of September. Diurnal emergence was studied on two occasions, in July and in August. Most of the insects emerged during dusk and dawn. Species composition and degree of water mite infection of the collected nematocerans were studied. Host range and specific attachment sites of the different water mite taxa could only be established on the genus or family-level, with the exception of the most common water mite species Hydrodroma despiciens. In addition to its main host Chaoborus flavicans, this mite species infested 16 chironomid species with Corynoneura sp., Cryptocladopelma viridula, Pseudochironomus prasinatus and Tanytarsus lactescens as new records. The larvae of Hydrodroma despiciens were attached almost exclusively to the thorax of the imagines. Chaoborus flavicans, and within the Chironomidae Procladius sp. of the subfamily Tanypodinae, showed the highest average mite load. Species of the subfamily Chironominae were also heavily infested (e.g. Microtendipes sp., infestation rate 76 % with a maximum mite load of 18). Within the representatives of the subfamily Orthocladiinae however, only low infestation rates occurred with maximum one larva per host. Finally, problems like the synchronization of the life-cycles of hosts and parasites and strategies of coexistence between the different water mite taxa parasitizing one host are discussed.  相似文献   
4.
The segmentation gene hierarchy of Drosophila melanogaster represents one of the best understood of the gene networks that generate pattern during embryogenesis. Some components of this network are ancient, while other parts of the network have evolved within the higher Diptera. To further understand the evolution of this gene network, we are studying the role of gap genes in a representative of a basally diverging dipteran lineage, the moth midge Clogmia albipunctata. We have isolated orthologues of all of the Drosophila trunk gap genes from Clogmia, and determined their domains of expression during the blastoderm stage of development, in relation to one another, and in relation to the expression of even-skipped (Calb-eve), a component of the pair-rule system that is directly regulated by the gap genes in Drosophila. We find that hunchback (Calb-hb), Krüppel (Calb-Kr), knirps (Calb-knl), giant (Calb-gt) and tailless (Calb-tll) are all expressed in patterns consistent with a gap segmentation role during blastoderm formation, but huckebein (Calb-hkb) is not. In the anterior half of the embryo, the relative positions of the gap gene expression domains in relation to one another, and in relation to the eve stripes, are rather well conserved. In the posterior half of the embryo, there are significant differences. Posteriorly, Calb-gt is expressed only transiently and very weakly, in a domain that overlaps entirely with that of Calb-knl. At late blastoderm stages, none of the candidate genes we have tested is expressed in the region between the posterior Calb-knl domain and Calb-tll. It is likely that the regulation of Calb-eve expression in this posterior region depends on combinations of gap gene factors that differ from those utilised for the same stripes in Drosophila. Both the gap and the pair-rule patterns of gene expression are dynamic in Clogmia, as they are in Drosophila, shifting anteriorly as blastoderm development proceeds.  相似文献   
5.
The ommatidial lens surfaces of the compound eyes in several species of files (Insecta: Diptera) and a related order (Mecoptera) were analyzed using a recently developed Raman-atomic force microscope. We demonstrate in this work that the atomic force microscope (AFM) is a potentially useful instrument for gathering phylogenetic data and that the newly developed Raman-AFM may extend this application by revealing nanometer-scale surface chemistry. This is the first demonstration of apertureless near-field Raman spectroscopy on an intact biological surface. For Chrysopilus testaceipes Bigot (Rhagionidae), this reveals unique cerebral cortex-like surface ridges with periodic variation in height and surface chemistry. Most other Brachyceran flies, and the "Nematoceran" Sylvicola fenestralis (Scopoli) (Anisopodidae), displayed the same morphology, while other taxa displayed various other characteristics, such as a nodule-like (Tipula (Triplicitipula) sp. (Tipulidae)) or coalescing nodule-like (Tabanus punctifer Osten Sacken (Tabanidae)) morphology, a smooth morphology with distinct pits and grooves (Dilophus orbatus (Say) (Bibionidae)), or an entirely smooth surface (Bittacus chlorostigma MacLachlan (Mecoptera: Bittacidae)). The variation in submicrometer structure and surface chemistry provides a new information source of potential phylogenetic importance, suggesting the Raman-atomic force microscope could provide a new tool useful to systematic and evolutionary inquiry.  相似文献   
6.
Construction of the middle and hind coxae was investigated in 95 species of 30 nematoceran families. As a rule, the middle coxa contains a separate coxite, the mediocoxite, articulated to the sternal process. In most families, this coxite is movably articulated to the eucoxite and to the distocoxite area; the coxa is radially split twice. Some groups are characterized by a single split. The coxa in flies is restricted in its rotation owing to a partial junction either between the meron and the pleurite or between the eucoxite and the meropleurite. Hence the coxa is fastened to the thorax not only by two pivots (to the pleural ridge and the sternal process), but at the junction named above. Rotation is impossible without deformations; the role of hinges between coxites is to absorb deformations. This adaptive principle is confirmed by physical modelling. Middle coxae of limoniid tribes Eriopterini and Molophilini are compact, constructed by the template of hind coxae. On the contrary, hind coxae in all families of Mycetophiloidea and in Psychodidae s.l. are constructed like middle ones, with the separate mediocoxite, centrally suspended at the sternal process. These cases are considered as homeotic mutations, substituting one structure with a no less efficient one.  相似文献   
7.
记述中国双翅目摇蚊科寡脉摇蚊亚科1新记录属--近北摇蚊属Paraboreochlus Thienemann,1939,对新记录种--冲绳近北摇蚊P.okinawanus Kobayshi&Kuranishi进行了重新描述;提供了世界上该属雄虫分种检索表和地理分布图。  相似文献   
8.
The results of a revision of the Sciaridae (Diptera: Nematocera) from the British Isles are presented, carried out as a preliminary to the preparation of a new Handbook for the identification of the British and Irish fauna of this family. A total fauna of 263 species is confirmed, including many species new to the British Isles: 111 new to Great Britain and 32 new to Ireland. Epidapus ( Pseudoaptanogyna ) echinatum Mohrig & Kozánek, 1992 , hitherto known only from North Korea, is newly recorded from Europe. Six species are described as new to science: Bradysia austera Menzel & Heller sp. nov. , Bradysia ismayi Menzel sp. nov. , Bradysia nigrispina Menzel sp. nov. , Corynoptera flavosignata Menzel & Heller sp. nov. , Corynoptera uncata Menzel & Smith sp. nov. and Epidapus subgracilis Menzel & Mohrig sp. nov . The following new synonymies are proposed: Leptosciarella nigrosetosa (Freeman, 1990) =  Leptosciarella truncatula Mohrig & Menzel, 1997 ; Sciara nursei Freeman, 1983 =  Sciara ulrichi Menzel & Mohrig, 1998. Many misidentifications in the previous literature are corrected. Details of the collection data and location of specimens examined are provided under each species. The localities from which Sciaridae were collected in the British Isles are documented by modern county and grid references and the habitat indicated where known, to assist in assessing the ecological requirements of each species.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 1–147.  相似文献   
9.
Summary The mapping of the compound eyes onto the visual neuropils and the cell types in the lamina and the lobula complex of Bibionidae (Diptera) were studied by means of extracellular cobalt injections and Golgi impregnations. Dorsal and ventral eyes in males map into separate dorsal-and ventral neuropils up to the level of the lobula complex. The dorsal-eye lamina is unilayered, while the ventral-eye lamina in males and the lamina in females are multilayered: layers A and C are invaded by en-passant terminals of long visual fibres, layer B by the terminals of short visual fibres. Long visual fibres have a short and a long terminal in the ventral medulla with terminal specialisations in three distinct layers. Only one type of receptor ending exists in the dorsal medulla, the terminal branches of which are restricted to one layer only. Arrays of contralateral neurones are found in the medial part of the dorsal lobula, which receives input from the zone of binocular vision of the ipsilateral dorsal eye, and in the posterior dorsal lobula and lobula plate. The dorsal lobula plate contains large tangential neurones, the dendritic arborisations of which are revealed by cobalt injection into the thoracic ganglia. The divided brain of male bibionids offers the opportunity to investigate separately the nervous systems involved in sex-specific visually guided flight behaviour and in general visually guided flight control.  相似文献   
10.
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