Integrative taxonomy improves understanding of native beneficial fauna: revision of the Nearctic Peristenus pallipes complex (Hymenoptera: Braconidae) and implications for release of exotic biocontrol agents

The Nearctic Peristenus pallipes complex (Hymenoptera: Braconidae) consists of two species groups that are further divided into nine species, separated largely using ecological rather than morphological differences. The species are re‐examined with an integrative approach using morphometric multivariate ratios, molecular (COI and CytB), and ecological data to test the validity of the nine species. The data support only three valid species [P. dayi Goulet, P. mellipes (Cresson) and P. howardi Shaw] rather than nine. New synonymies include: P. braunae Goulet under P. dayi Goulet 2006 syn.n. ; P. carcamoi Goulet, P. otaniae Goulet and P. pseudopallipes (Loan) under P. mellipes (Cresson) syn.n. , and finally P. broadbenti Goulet 2006 and P. gillespiei Goulet 2006 under P. howardi Shaw 1999 syn.n . In light of these taxonomic revisions, the biology and distributions of the Nearctic P. pallipes complex are updated, resulting in three morphologically variable, widespread, multivoltine species rather than nine largely univoltine species with patchy distributions. The integrative taxonomic approach used here allowed for a more accurate delineation of native fauna and their potential to be competitively displaced by foreign biocontrol agents.     

Regulation of Turgor Pressure by Suspension-Cultured Tobacco Cells

Turgor regulation and effects of high NaCl and water deficiton growth and internal solutes were studied after transferringtobacco cells from control culture medium (osmotic pressure= 0.13–0.15 MPa at time of transfer) to culture mediumcontaining either 82 mol m^–3 NaCl or 150 mol m^–3melibiose (osmotic pressure of media = 0.62 MPa). Followingtransfer to media with higher osmotic pressure, expansion rateand turgor pressure were reduced. Within 24 h of imposing thewater deficit, expansion rate had returned to that of cellsin control culture medium. However, by 24 h, turgor pressurehad only risen from 0.2 MPa to 0.65 MPa in the NaCl treatmentand to 0.53 MPa in the melibiose treatment, while it was 0.73MPa in the control treatment. Furthermore, turgor pressure remainedwithin 0.05 MPa of these respective values for the rest of the(75 h) experiment. These results suggest differences in bothcell wall properties (extensibility and/or threshold turgor)and the level at which turgor is maintained for cells in thevarious treatments. Solutes contributing nearly all (82–97%) of the osmoticpressure in cells were identified. The initial (up to 24 h)increases in turgor pressure were mainly due to increases insolute concentrations caused by relatively slow expansion rates.However, increased Na⁺ and Cl ^– uptake contributed toincreased turgor pressure in the NaCl treatment and caused turgorpressure of cells in this treatment to increase faster thanin the melibiose treatment. Likewise, expansion rate rose morequickly in the NaCl than in the melibiose treatment. After 24h, maximum expansion rate was reached and concentrations ofmost internal solutes began to decrease. Nevertheless, turgorpressure remained relatively constant. The constancy of turgorpressure was due to increased glucose uptake rates relativeto controls, with consequent increases in concentrations ofsucrose, glucose and fructose and, in cells in the melibiosetreatment, of organic acids. Glucose uptake was slower in theNaCl than in the melibiose treatment but higher turgor pressurewas maintained in the NaCl treatment due to high uptake of Na⁺and Cl^–. Glucose uptake appears to respond to a systemof turgor regulation, but further experiments are required toconfirm this and to determine whether Na⁺ and Cl^– uptakealso respond to a system of turgor regulation. Key words: Salinity, water deficit, growth     

Sedimentation of Bovine Rhodopsin—Digitonin Micelles

RHODOPSIN, the photo-sensitive pigment of vertebrate vision receptors, consists of the lipoprotein opsin bound to the 11-cis isomer of retinal. Light isomerizes the 11-cis configuration to the all-trans, which makes the pigment unstable, leading eventually to the dissociation of the retinal from the lipoprotein. The belief that these dark steps involve conformational changes in the lipoprotein moiety stems from spectroscopic measurements which show the disappearance of lipoprotein-chromophore interactions and from kinetic and thermodynamic considerations^1–5, but more direct evidence has come from the changes in circular dichroism and optical rotatory dispersion which occur with bleaching^6–9. There is also an increase of Stokes radius on bleaching¹¹.     

Aphid saliva

Within the Aphidoidea, most species of Aphididae, as long as they are in small numbers and not carrying plant viruses, do little perceptible damage to their food plants. In species that cause toxicoses, it is usually assumed that some component of the saliva must be responsible. Paradoxically, however, the salivary enzymes of Aphididae are similar to those that already occur in plants – oxidases and enzymes that depolymerize polysaccharides – and the salivary enzymes are injected in very small amounts relative to their counterparts in the plant. Damage to plants triggers defensive, biochemical responses, and it is suggested that the injected enzymes serve mainly to divert or counter responses at the immediate interface of stylets and plant tissues. The saliva of Aphididae contains non-enzymic, reducing compounds which, in the presence of oxidases, can combine with and inactivate defensive phytochemicals – including those released in response to damage and transported in the phloem sieve tube sap on which Aphididae feed. Salivary and gut oxidases deactivate ingested phytochemicals by oxidative polymerization. Aphididae inject saliva into sieve tubes before sustained ingestion of sap, and this saliva has been presumed to condition the sieve tubes, but in what way remains unclear. It is suggested that there is a dynamic biochemical interaction between aphids and plants; that the interaction is usually well balanced for most of the Aphididae; hence, no outcome is readily observable. Where a significant imbalance occurs, however, either the aphid is unable to feed, i.e. the plant is resistant, and/or the aphid does not effectively counter a hypersensitive response. Not all plant responses are disadvantageous to aphids. Gall-forming Aphidoidea trigger and control abnormal growth in the plant to the insects' advantage, possibly by eliciting vigorous oxidation in selective meristematic tissues, thereby limiting supply of molecular oxygen and inhibiting oxygen-dependent growth-controls. Current problems and possible approaches for further research are reviewed.     

Narrow-leafed Lupins with Restricted Branching

Crop phenology is one of the most important characters influencingproductivity in a given environment. Narrow-leafed lupin (Lupinusangustifolius L.) is a major grain legume crop in southern Australiawith general phenological adaptation to this Mediterranean-typeenvironment. However, it is an indeterminate crop with severalassociated limitations to productivity, such as overlappingvegetative and reproductive growth, late grain filling and sometimesexcessive vegetative growth. Here we studied two novel typesof narrow-leafed lupin with restricted branching, which mightbe useful for overcoming these problems. These restricted branchinglupins arose spontaneously within a breeding population, inthe case of ‘Tallerack’, and within a farmer's cropin the case of ‘ Hurst’ and we compared them withthe ‘Merrit’, which is widely grown and has thenormal indeterminate branching habit. The morphology and developmentof the main shoot of these genotypes were similar. However,‘Hurst’ had much larger leaves. There were alsostriking differences in the lateral branches of the restrictedbranching types; they had fewer leaves than ‘Merrit’and flowered earlier. These differences were most marked in‘ Hurst’, where the upper main stem branches werereduced to a single floret in the axil of main stem leaves,and these flowers often exhibited abnormal morphology. Copyright2000 Annals of Botany Company Lupinus angustifolius L., narrow-leafed lupin, adaptation, development, morphology, branching, leaves, mutant, plastochron, phyllochron, floral initiation, flowering.     

Eubrachythoracid arthrodires with tubular rostral plates from Gogo, Western Australia

Two monotypic genera of tubular-snouted eubrachythoracid arthrodires are described from the Upper Devonian Gogo Formation of Western Australia as Rolfosteur gen nov. and Tubonnsus gen. nov. They are most closely related to Camuropiscis Dennis & Miles, also from the Gogo Formation, and all three are therefore placed in the family Camuropiscidae nov. Rolfosteus and Tubonasus are jointly the sister-group of Camuropiscis .     

Prevention of aluminium toxicity with supplemental boron. II. Stimulation of root growth in an acidic, high-aluminium subsoil

Root growth inhibition is an early symptom of Al toxicity and B deficiency. Our hypothesis is that Al toxicity may induce B deficiency, and it was our objective to determine if incorporation of supplemental B would promote root penetration into an acidic, high-Al subsoil. Alfalfa (Medicago sativa L. cv. Hy-Phy) was grown in slanted tubes with a Plexiglas window along their length. The top half of the tub contained silt loam soil and the bottom half contained subsoil from the Bt1 horizon (26% Al saturation) of a Creldon silty clay loam. Both soils originally contained 0–9 kg B ha^?1. When root growth was measured in the bottom half of the high-A1 subsoil, all measurements—depth of rooting, total root growth, final root lengths and root dry weight—demonstrated greater root growth in treatments where additional B was incorporated into the high-Al subsoil. Results from this soil study extend those obtained in our hydroponic study in which supplemental B presented Al inhibition of root growth. Boron concentrations may need to he increased under acidic ‘high-Al’ soil conditions to promote root penetration into these soil zones, and this could be especially important during periods of drought stress.