Effects of temperature on phenological synchrony and altitudinal distribution of jumping plant lice (Hemiptera: Psylloidea) on dwarf willow (Salix lapponum) in Norway

Summary.

• 1 The geographical distributions of three species of jumping plant lice (psyllids) along an altitudinal transect (988–1300 m a.s.l.) in southern Norway were restricted within the range of their host plant Salix lapponum. One species, Cacopsylla propinqua, occurred at all sampling locations between 988 and 1222 m, whereas C.palmeni was confined to higher altitudes (1153–1222 m) and C.brunneipennis was more abundant at lower altitudes (988–1101 m).
• 2 C.brunneipennis and C.palmeni developed only on female catkins. Development times of catkins and psyllids were similar (approximately 50 days) and successful psyllid development depended on close phenological synchrony with catkins.
• 3 Thermal requirements for development of female catkins were greater at low altitude (988 m) compared with higher altitude (1222 m), showing local adaptation of S.lapponum to altitude. In general, thermal requirements of psyllids were less than those of catkins at the same location. C.brunneipennis had higher thermal requirements than C.palmeni.
• 4 Field experiments, using polythene enclosures to elevate temperatures at two sites at different altitudes (by 0.6–1.4 deg. C), showed that insects had an enhanced relative rate of development under elevated temperatures compared with their host plants.
• 5 Indices of phenological synchrony were calculated from thermal requirements of psyllids and catkins. Under elevated temperatures, phenological synchrony decreased at both sites. This resulted in the subsequent development of smaller adult insects at low altitude, although at higher altitude, insects developing under elevated temperatures were larger and had a higher survival rate compared with controls.
• 6 Effects of temperature on phenological synchrony may explain the limits to the geographical range of psyllids. The consequences of climate change on psyllid populations will depend on the effects of decreased phenological synchrony on insect development and this may differ within the insect's geographical range.

     

Heterophylly in Ranunculus flabellaris Raf.: The Effect of Abscisic Acid

Ranunculus flabellaris Raf., the Yellow Water-Crowfoot, is aheterophyllous semi-aquatic dicotyledonous plant, showing strikingmorphological and anatomical differences between terrestrialleaves and those formed underwater. After plants are submergedin a 25 µM solution of abscisic acid, leaves are producedat a normal rate but they exhibit many of the characteristicsof terrestrial leaves. Ranunculus flabellaris Raf., Yellow Water-Crowfoot, heterophylly, abscisic acid     

ACETYLTRIETHYLCHOLINE: A CHOLINERGIC FALSE TRANSMITTER IN CAT SUPERIOR CERVICAL GANGLION AND RAT CEREBRAL CORTEX

The accumulation and metabolism of [¹⁴C]triethylcholine by cat superior cervical ganglia [rested or stimulated (20 Hz)] and by rat cerebral cortex minces was measured. In ganglia, preganglionic nerve stimulation increased the accumulation (2.4 fold) and the acetylation (5.7 fold) of triethylcholine; however the depletion of the ganglion's acetylcholine content was 9.5 times greater than the amount of acetyltriethylcholine synthesized. In the presence of eserine, neither stimulated nor rested ganglia synthesized any extra (surplus) acetyltriethylcholine. It is concluded that the rate-limiting step in acetyltriethylcholine synthesis is the acetylation of triethylcholine by choline acetyltransferase. Subsequent preganglionic nerve stimulation of ganglia, which had been stimulated during the exposure to [¹⁴C]-triethylcholine, caused the increased release of only acetyltriethylcholine; the release was frequency-dependent, required the presence of Ca²⁺, and was blocked by increasing the ratio of Mg²⁺/Ca²⁺ in the perfusion fluid. All of the acetyltriethylcholine which had been accumulated was available for release. Rat cerebral cortex also accumulated triethylcholine and acetylated about 3% of the accumulated choline analogue. Subsequent stimulation by high K⁺ (46 mM)-atropine (3 μM) caused the increased release of acetyltriethylcholine from the cortex and this release required the presence of Ca²⁺. Triethylcholine can therefore form a cholinergic false transmitter in the cat superior cervical ganglion and the rat cerebral cortex.     

The sciarid fauna of the British Isles (Diptera: Sciaridae), including descriptions of six new species

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.     

Extensive intraspecific genetic diversity of a freshwater crayfish in a biodiversity hotspot

1. The freshwater crayfish Cherax dispar (Decapoda: Parastacidae) inhabits coastal regions and islands of South East Queensland, Australia. We hypothesised that populations of C. dispar on different islands would be more genetically divergent from each other than populations from different drainages within the same island or on the mainland. 2. Phylogenetic and phylogeographic analyses were conducted on two mitochondrial genes (cytochrome oxidase subunit I & 16S ribosomal DNA) and one nuclear gene (Internal Transcribed Spacer region 2). Phylogeographic patterns were compared with those for other freshwater organisms in the area. 3. Deep genetic divergences were found within C. dispar, including four highly divergent (up to 20%) clades. The geographic distribution of each of the clades revealed strong latitudinal structuring along the coast rather than structuring among the islands. The high genetic divergence observed among the C. dispar clades was estimated to have pre‐dated island formation and may represent ancient river drainage patterns. 4. A restricted distribution was observed for the most divergent clade, which was discovered only on two of the sand islands (North Stradbroke Island and Moreton Island). Furthermore, strong phylogeographic structuring was observed within this clade on North Stradbroke Island, where no haplotypes were shared between samples from opposite sides of the island. This low connectivity within the island supports the idea that C. dispar rarely disperse terrestrially (i.e. across watersheds).     

Microfossils and evidence of land plant evolution

Resolving the question of (1) land plant and (2) vascular land plant evolution is a complex problem. It requires a continued, multidisciplinary effort. We are all grateful to Dianne Edwards and her colleagues (Edwards et al. 1979) for pursuing one such line of research with careful attention to morphology and stratigraphy. Their efforts, however, are confined to one small part of the globe, and they perforce involve only one type of evidence effective with regard to questions of vascular plant evolution once the land estate has been reached. They do not deal with the basic question of vascular and non-vascular land plant origins. The so-called Přídolí benchmark that remained the sine qua nun for vascular plant evolution when Dianne Edwards began her studies has now been irrevocably breached. What other supposedly sacrosanct benchmarks will also crumble as the result of future discoveries, now that vascular plants have been recovered from lower Ludlovian strata? Nevertheless, pre-Devonian plant megafossils are too rare to yield definitive results with regard to the origin of land plants prior to the vascular estate, even though they could in principle (as emphasized by Edwards et al. 1979) provide the least ambiguous evidence. We must look elsewhere than to megafossils for evidence suggesting links in time between green algal ancestors, major groups of living green land Plants, and the many extinct groups of enigmatic higher land plants in the crucial Early Paleozoic time interval.     

Elevationally biased avian predation as a contributor to the spatial distribution of geometrid moth outbreaks in sub‐arctic mountain birch forest

1. Population dynamics and interactions that vary over a species' range are of particular importance in the context of latitudinal clines in biological diversity. Winter moth (Operophtera brumata) and autumnal moth (Epirrita autumnata) are two species of eruptive geometrids that vary widely in outbreak tendency over their range, which generally increases from south to north and with elevation. 2. The predation pressure on geometrid larvae and pupae over an elevational gradient was tested. The effects of background larval density and bird occupancy of monitoring nest boxes on predation rates were also tested. Predation on larvae was tested through exclusion treatments at 20 replicate stations over four elevations at one site, while pupae were set out to measure predation at two elevations at three sites. 3. Larval densities were reduced by bird predation at three lower elevations, but not at the highest elevation, and predation rates were 1.9 times higher at the lowest elevation than at the highest elevation. The rate of predation on larvae was not related to background larval density or nest box occupancy, although there were more eggs and chicks at the lowest elevation. There were no consistent differences in predation on pupae by elevation. 4. These results suggest that elevational variation in avian predation pressure on larvae may help to drive elevational differences in outbreak tendency, and that birds may play a more important role in geometrid population dynamics than the focus on invertebrate and soil predators of previous work would suggest.     

Uptake, translocation and metabolism of fluazifop-butyl in Setaria viridis

The uptake and translocation of fluazifop-butyl was investigated in Setaria viridis. Young plants (three to four leaves) with a portion of the second, third or fourth leaf covered, were sprayed with a dose equivalent to 0.25 kg a.i. ha-¹. ¹⁴C-fluazifop-butyl was subsequently applied to the unsprayed area and the treatment resulted in plant death within 2 wk. Uptake by leaf 3 was rapid, with less than 5% of the applied dose remaining on the leaf surface after 24 h. The highest proportion of ^14C-activity was retained in the treated portion of the leaf. Only 2% of the applied dose was translocated from leaf 3 and 0. 76% accumulated in the apical meristem. Uptake by the younger leaf 4 was more rapid and the pattern of translocation differed in that more ¹⁴-^-activity accumulated in apical meristematic tissue. 6–30% of the applied dose was undetected and this was greatest when foliar uptake was slow. Artificial leaf surface experiments indicated that this undetected activity may have been due to volatility of fluazifop-butyl or degradation to volatile products. ^14C-activity extracted from treated leaves was identified as fluazifop-butyl, fluazifop acid and polar conjugates. The major ¹⁴C-activity extracted from the apical meristem was fluazifop acid and no fluazifop-butyl was detected in this extract.