Über Wirtspflanzen und Parasitismus einiger mitteleuropäischerRhinanthoideae (Scrophulariaceae)

None of the 27 studiedRhinanthoideae is host-specific. Some host plants are preferred (e.g.Rosaceae, Fabaceae, Lamiaceae, Asteraceae, Cyperaceae, andPoaceae), others are strictly avoided (e.g.Orchidaceae). Self-parasitism and parasitism on rhizomes are wide-spread. This and the number of haustoria developed are closely related to number of host plants available. Most of theRhinanthoideae studied have haustoria also at the main root. No serious injury of host plants byRhinanthoideae under natural conditions can be demonstrated.

     

Zur Evolution des Parasitismus bei denScrophulariaceae undOrobanchaceae

Different growth forms and life forms of parasitic plants inScrophulariaceae andOrobanchaceae were studied from a comparative point of view. The most primitive form of parasitism is found in small, annual root parasites. Small wart-haustoria in the hypocotylar region of larger root parasites point towards a tendency of these plants to form hypocotylar tubercles as primary haustoria. Wart-haustoria also can develop on scale leaves, demonstrating an evolutionary trend towards the most advanced form of parasitism in these two families the formation of large leaf haustoria.

     

Host-specificity of a root borer,Bembecia chrysidiformis [Lep.: Sesiidae], a potential control agent forRumex spp. [Polygonaceae] in Australia

Bembecia chrysidiformis (Esper) [Lep.: Sesiidae] was examined for its natural history and specificity toRumex spp. (Polygonaceae) which are weeds in Australia. Adults of this southern European insect appear in late spring to summer. Eggs are laid on the dried, seed bearing stems of perennialRumex plants. The larvae tunnel inside the root during summer through to the next spring. In nature, the larvae are round inRumex species of the subgeneraRumex andAcetosa. In host-specificity tests with 1st instar larvae, the roots of a number of genera within thePolygonaceae were attacked. Larvae died on a range of plants from other families except inPersea americana Miller(Lauraceae), Helianthemum nummularium (L.) Miller (Cistaceae) andQuercus ilex L. (Fagaceae) where larvae fed on the stems. The insect was judged safe for release in Australia by assessing aspects of its biology, its known host plants, and the lack of reported attack on other plants.      

Das Rhizoid vonUlothrix zonata (Chlorophyceae)

Ulothrix zonata was studied under natural conditions in situ on slides exposed in a river. On them specimens grow in all stages of development. Older filaments are fixed on the substrate not only by the pointed basal cell but mainly by a branched, horizontally expanded rhizoid produced by this cell. The rhizoid grows in correlation with the growth of the filament as a whole. In addition to the basal cell the following cells of the lower portions of the filament are incapable of division and reproduction. Through these cells the upper fully vital cell grows downwards in older stages.

     

Entwicklungsgeschichte und Ultrastruktur des Pollenkitts beiTilia (Tiliaceae)

The pollenkitt ofTilia platyphyllos andT. tomentosa is produced during the tetrade-stage by the tapetum plastides. After tapetum degeneration pollenkitt and accompanying substances are deposited predominantly in the intrabacular spaces of the exine, and only in small quantities on the surface of the exine itself.

     

Sind Farne Kormophyten? Eine Alternative zur Telomtheorie

Modern ideas concerning cormophyte phylogeny are strongly influenced by the telome theory. Erect growth, radial symmetry, dichotomy, protostely and eusporangial structure are considered to be primitive features. Yet, the cormus needs redefinition. TheHypolepidaceae (s. str.) are shown to have rather a two-dimensional thallus than a three-dimensional cormus. Their so-called rhizome develops a continuous areophore margin which is connected with the margin of the fronds. The longitudinally inserted fronds and branches are produced by the terminal rhizome meristem which itself grows in many respects like the apical frond meristem. The rhizomes ofDennstaedtiaceae and theDavallia-type of rhizomes are intermediate between thisHypolepis-type and the true cormus-type. TheHypolepis-type is compared with fern prothalli. Under perhumid tropical conditions higher land plants may have evolved from small, creeping, two-dimensional fern prothallium-like progenitors with isomorphous gameto- and sporophytes.

Vorgetragen auf der Morphologentagung in Zürich 1975.     

Intraspecific Variation in Chemical Attraction of Rice to Insect Predators

The olfactory response of predators of the brown planthopper,Nilaparvata lugensStål, to different genotypes of rice (14 cultivars and breeding lines ofOryza sativaL. and 1 wild species,Oryza nivaraSharma et Shastry) was measured in an airflow olfactometer. Odor from rice plants attracted more females of the mirid predatorCyrtorhinus lividipennisReuter than plain air (control) on only 6 of the 15 rice genotypes. Orientation ofC. lividipennistoward volatiles of certain rice genotypes was apparent even when the plants were free of the brown planthopper. However, the predator distinguished between prey-infested and uninfested plants and preferred plants with eggs over plants with nymphs. The predator did not distinguish different stages of plant growth (vegetative, booting, or flowering). Plants artificially injured to simulate brown planthopper oviposition wounds were not as attractive to the predator as plants on which the planthopper had oviposited. The preassay preconditioning on the cultivar TN1 did not produce a predator bias for this genotype. This suggests that rearing effects or chemically mediated associative learning reported for some natural enemies did not influenceC. lividipennis'host response. Results with another predator, the coccinellidMicraspis hirashimaiSasaji, produced less consistent behavior. Planthopper-infested plants attracted more females ofM. hirashimaithan unifested plants in only 1 of the 12 rice genotypes evaluated. Implications for augmenting predators by rice cultivar selection and modification are discussed.     

Considérations sur l'Anatomie dePosidonia oceanica (Zosteraceae)

The rhizome ofPosidonia oceanica shows an arrangement of vascular tissue not yet observed in other plants: a series of vascular cylinders all laid out in a single plane. There is a central cylinder, an atactostele, and six lateral cylinders, three on each side. These lateral cylinders are quite unusual too, each of them being formed by a single perixylematic bundle. For these structures the authors suggest the term haploendoleptostele; the whole arrangement might be called xestomeristele.

     

Vergleichende Mikromorphologie der Narbenoberflächen bei den Angiospermen; Zusammenhänge mit Pollenoberflächen bei heterostylen Sippen

Stigmatic surfaces of about 250 species from more than 100 families were examined by scanning electron microscopy. There are five main groups which differ by the amount of secretion, the morphology of the surface and the distribution of receptive cells. The types of stigmatic surfaces are often remarkably constant on the family level.Ericaceae andLiliaceae are examples for very heterogenous families. Particular interest was paid to heteromorphic (heterostylous and cleistogamous) species. In most heterostylous species there is a close morphological correlation between the stigmatic surface and the sculpture of compatible pollen. Heterostyly was established for the genusGoniolimon. The dimorphism of plants with chasmogamous and cleistogamous flowers is a phenomenon which is not comparable to the polymorphism of heterostylous forms.

     

Zwergstrauchige Arten der FlechtengattungCaloplaca

The frutescent species of the lichen genusCaloplaca are usually united in sect.Thamnoma, but they do not form a natural group. They are derived from different species groups within sect.Gasparrinia from different parts of the world, presumable from species having scleroplectenchymes in cortex and medulla. The algal cells are concentrated between the scleroplectenchymatic strands in large and dense groups, from where medullary plectenchyme extends to the cortex and forms characteristic pseudocyphellae there.—Most of the species seem to be ornithocoprophilous; they grow on rocks along marine coasts where much fog is induced by cold currents.—Caloplaca cribrosa is endemic in Tasmania and New Zealand,C. regalis and the doubtfulC. ambitiosa belong to the antarctic element.C. fragillima from central Chile seems to be propagated by thallus fragments.C. coralloides andC. thamnodes are endemic to California and Baja California respectively.C. cladodes from the Rocky Mountains deviates in many characteristics from the other species i.a. by it different ontogenetic development, reduced spore septum, and cementing amyloid polysaccharides within the scleroplectenchymatic strands. The African species are characterized by their distinctly dorsiventral lobes and usually possess oil cells in some of the paraphyses.Caloplaca bonae-spei, C. fragillima andC. thamnodes are new to science.

     

Chamaesphecia doryliformis [Lep.: Sesiidae], a second root borer for the control ofRumex spp. [Polygonaceae] in Australia

The host-specificity and biology ofChamaesphecia doryliformis (Ochsenheimer) [Lep.: Sesiidae] are described and the insect is assessed for its potential as a biological control agent for weeds of the genusRumex (Polygonaceae) in Australia. The insect is found in the western Mediterranean region, chiefly in north Africa. Adults emerge from pupation in late spring to summer when they lay eggs. The larvae feed inside the roots of post-reproductive plants belonging to the subgeneraRumex andAcetosa. In host-specificity tests 1^st instar larvae attacked only plants of thePolygonaceae. The insect was judged safe to release in Australia after assessing its level of host-specificity, and attributes of its biology which indicate that native AustralianPolygonaceae will not be endangered.      

Wuchsform und Organisation vonMonsonia nivea (Geraniaceae) unter besonderer Berücksichtigung der Blattstieldornen

Monsonia nivea is a hemicryptophyte which shows spiny petioles after the loss of leaf blades. Anthocladial inflorescences and their supporting vegetative parts are spineless. Spines are formed only by vigorous rosettes. Similar spiny petioles can be found in all other genera of the tribeGeranieae.

     

Ornithophilie auf den Canarischen Inseln

(1) On the Canary Islands and Madeira typical bird-flowers occur in at least twelve species of six genera, although true flower-birds are absent. This inconsistency is in part elucidated by field observations on exotic and wild plants of Tenerife. —(2) In the Botanical Garden of Orotava it could be observed that various ornithophilous plants, which were introduced there, were visited by indigenous birds for nectar and in one case (Orthostemon) for food tissue. Of the three bird species involved, an endemic race of Chiffchaff (Phylloscopus collybita) and resident Blackcaps (Sylvia atricapilla) exploit, and pollinate, flowers legitimously, while the Wild Canary (Serinus canaria) is predominantly a destructive nectar robber. —(3) The insular Chiffchaff also proved to be a regular pollinator in the wild, at least ofCanarina canariensis andIsoplexis canariensis, two ornithophilous paleoendemics. Ornithophily, thus, is naturally practised on the island, though by birds basically insectivorous. —(4) A list of Macaronesian plants bearing the more or less complete ornithophilous syndrome is presented, including newly recognizedTeucrium heterophyllum andScrophularia calliantha. —(5) On biogeographical and faunistic grounds it is presumed that the modern visitors of Canarian bird flowers are secondary rather than the original partners of the continental tertiary flora in which these plants originated. Palearctic immigrants, when becoming resident on the islands during and since the Pleistocene, adopted facultative nectar feeding, entering an orphaned food niche. Casual flower visits in Europe suggest a certain predisposition of the Chiffchaff and the Blackcap for the exploitation of flowers. — (6) The ability of unspecialized birds to acquire nectardrinking spontaneously and to pass this habit on to their offspring, is demonstrated by a population of Tree Sparrows (Passer montanus) which have visited ornithophilousKniphofia (Liliaceae) in Berlin for several years.

     

Attraction of a generalist predator towards herbivore-infested plants

The occurrence and strength of interactions among natural enemies and herbivores depend on their foraging decisions, and several of these decisions are based on odours. To investigate interactions among arthropods in a greenhouse cropping system, we studied the behavioural response of the predatory bug Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) towards cucumber plants infested either with thrips (Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)) or with spider mites (Tetranychus urticae Koch (Acari: Tetranychidae)). In greenhouse release-recapture experiments, the predatory bug showed a significant preference for both thrips-infested plants and spider mite-infested plants over clean plants. Predatory bugs preferred plants infested with spider mites to plants with thrips. Experience with spider mites on cucumber leaves prior to their release in the greenhouse had no effect on the preference of the predatory bugs. However, this experience did increase the percentage of predators recaptured. Y-tube olfactometer experiments showed that O. laevigatus was more attracted to odours from plants infested with spider mites than to odours from clean plants. Thus, O. laevigatus is able to perceive odours and may use them to find plants with prey in more natural conditions. The consequences of the searching behaviour for pest control are discussed.     

Insect natural enemies of coffee green scales [Hemiptera: Coccidae] in Kenya and their potential for biological control ofCoccus celatus andC. viridis in Papua New Guinea

Coffee green scales,Coccus celatus De Lotto andC. viridis (Green), are major pests of coffee in Papua New Guinea (PNG). Surveys for insect natural enemies of coffee green scales were conducted in Kenya to find species suitable for introduction to PNG. Natural enemy communities in Kenya were found to be diverse, particularly those located in the central highlands where 3 primary parasitoids,Metaphycus stanleyi Compere,M. baruensis Noyes andDiversinervus stramineus Compere (Encyrtidae), were dominant onC. celatus andC. alpinus De Lotto. It is suggested that these 3 parasitoids may be potential biological control agents forC. celatus. Several insect predators were found associated withC. celatus in the central highlands but most were only common in ant-free scale populations. An aphelinid primary parasitoid,Coccophagus rusti Compere, was the only natural enemy ofC. viridis located. This species, however, could be of potential as a biological control agent, especially in view of its previous use in biological control against soft scales.      

Über die Phycobionten der SektionCystophora vonChaenotheca,insbesondereDictyochloropsis splendida undTrebouxia simplex,spec. nova

Chaenotheca brunneola is lichenized withDictyochloropsis splendida. Until now this member of theChlorococcales has been observed only twice and free-living. It reproduces by motionless daughter cells in the lichen thallus, but mainly by zoospores in the free-living state and under favourable conditions. Zoospore development has not been observed before and apparently depends on storage of starch which is repressed in the lichenized state. During zoospore activity this storage material is consumed. Zoospores possess two flagella which are inserted rather far apart from each other, one pulsating vacuole and a cup-shaped, not latticed chloroplast.Chaenotheca phaeocephala var.alpina, Ch. melanophaea andCh. chrysocephala are lichenized withTrebouxia. The phycobiont ofCh. chrysocephala, Trebouxia simplex, sp. n., differs from other sibs of the genus by the relative small size of the cells, the less marked differentiation of the chloroplast and certain details of cell division.

     

Host-specificity and virus-vector potential ofAphis chloris [Hemiptera: Aphididae], a biological control agent for St John's wort in Australia

Under laboratory conditionsAphis chloris Koch has been demonstrated to be specific to plants belonging to the genusHypericum. It can effect severe damage to its principal host,H. perforatum L., and shows good potential for contributing to the control of this noxious weed. Other species ofHypericum are less favoured hosts ofA. chloris and would not be endangered by it. A. chloris shows a high level of host-discrimination and does not transmit persistent viruses between non-host plants. Whereas in the laboratory it is capable of transmitting non-persistent viruses, it would contribute only marginally to the risk of virus transfer posed by the Australian aphid fauna as a whole, and its release would not necessitate changes to existing control practices, where these are required to reduce plant virus transmission. As a consequence,A. chloris is considered safe for release againstH. perforatum in Australia.      

Collections of natural enemies ofLeptinotarsa decemlineata [Coleoptera: Chrysomelidae] in Mexico, 1980–1985

Three trips were taken to central Mexico to search for natural enemies ofLeptinotarsa decemlineata (Say), in 1980, 1983, and 1985. 18 natural enemy species were found associated with 10 species ofLeptinotarsa. Asopine pentatomids dominate the collections, followed by tachnid parasites and hemipteran and coleopteran predators. Natural enemies may play a major role in regulating populations ofLeptinotarsa in Mexico. Their adaptability to northern climates is unclear.      

EineAnabaena-artige Cyanophycee mit auffallendem Zellteilungs- und Fadenzerfallsrhythmus

This paper deals with a filamentousCyanophycea from aSphagnum bog whose position in the current system is dubious. A characteristic feature, among others, is a certain rhythm of cell division and bipartition of the filaments. As a consequence, only 8-, 16- and 32-celled filaments are present in the population. An occasional disturbance of the rhythm is transitory. In the longitudinal direction the filaments exhibit mirror symmetry in regard to their middle.

     

Bemerkungen zur Cytologie einiger Arten der GattungSilene (Caryophyllaceae) aus Zentralgriechenland und Kreta

The chromosome numbers of several Greece species of the genusSilene L. from natural habitats are reported for the first time:S. sieberi, S. niederi, S. radicosa subsp.rechingeri, S. oligantha, S. skorpilii, S. schwarzenbergeri andS. fruticulosa. All species are diploid with 2n = 24 chromosomes, including 0, 2 or 4 SAT-chromosomes;S. niederi has B-chromosomes.