Detection and validation of EST‐derived SNPs for poplar leaf rust Melampsora medusae f. sp. deltoidae

We report the discovery, characterization and validation of 118 single nucleotide polymorphisms (SNPs) for poplar leaf rust Melampsora medusae f. sp. deltoidae identified using a gene‐targeted approach in an expressed sequence tag (EST) library. We developed a genotyping assay using the iPLEX? primer extension method for two multiplex assays of 28 and 22 SNPs.     

Differential responses of UK upland plants to nitrogen deposition

Native upland species, Nardus stricta , Eriophorum vaginatum , Erica cinerea and Vaccinium vitis-idaea were given 3 or 60 kg N ha⁻¹ yr⁻¹, over 2 yr, applied as a mist (NH₄NO₃). The high N treatment increased above-ground biomass in all four species, but only significantly in E. cinerea , E. vaginatum and N. stricta . Biomass increases in E. vaginatum and N. stricta resulted from enhanced tiller production rather than shoot elongation. Root growth increased in N. stricta , so that root:shoot ratio in this species was unchanged by N. Root growth in E. vaginatum , E. cinerea and V. vitis-idaea did not respond to N and their root:shoot ratios decreased. Tissue N concentrations increased in both shoots and roots of all species in response to N. The accumulated foliar N did not increase the proportion of N allocated to Rubisco and the photosynthetic capacities of N. stricta , E. vaginatum and V. vitis-idaea were unchanged. Thus growth responses to N were due to altered allocation rather than increased rate of photosynthesis per unit leaf area. The high N treatment increased flower production significantly in E. cinerea but not in the other species. Although in this experiment dwarf shrubs were more responsive than graminoids to N, in the field at current N inputs the enhanced tillering of the graminoids may be more competitively advantageous, especially where gaps develop in the canopy. Thus increasing N deposition may lead to increased grassiness of upland heath, and in particular, a spread of N. stricta .     

The Distribution of Na+, K+ and Glycinebetaine in Salicornia bigelovii

Stems of young actively growing Salicornia bigelovii were dissectedinto the three major tissue layers: vascular, spongy mesophylland palisade. Each layer was analysed for chlorophyll, ash (salt),protein and glycinebetaine content. When glycinebetaine contentwas based on protein content, the vascular and spongy mesophylllayers had nearly identical values. Correction for probableRuBP carboxylase content in the palisade layer gave a glycinebetaine/proteinratio similar to that of the other tissues. All three tissuelayers were found to contain significant amounts of salt. Key words: Salicornia bigelovii, Salt distribution     

Wandering behaviour and pupariation in tsetse larvae

Abstract .Following parturition, the third instar larva of Glossina morsitans morsitans West begins a wandering period in which it crawls to the site of pupariation. The duration of wandering can be drastically shortened by pinching or by denying the larva physical contact with the substrate. Contact with water increases the wandering period. Duration of subsequent activities appears to be rigidly fixed. At the end of the wandering period, the larva quickly progresses through a stereotypic sequence of behaviours that include immobilization and excretion of a liquid from the anus, retraction of the anterior segments, cuticular shrinkage, and tanning. Muscular activity and mechanical changes in the cuticle are reflected in changes of haemocoelic pressure. Muscular contractions produce pressure pulses that gradually increase in frequency and intensity, reaching a peak during retraction of the anterior segments. Changes in the mechanical properties of the cuticle cause a more gradual elevation of baseline pressure as the cuticle shrinks and loses its plasticity. As tanning begins, muscular activity ceases and haemocoelic pressure gradually decreases. In spite of its unusual early development within the confines of the female's uterus, the free-living larva shows the full behavioural repertoire observed in other cyclor-rhaphous Diptera at pupariation.     

Predicting the unexpected: using a qualitative model of a New Zealand dryland ecosystem to anticipate pest management outcomes

Pest management is expensive and there is often uncertainty about the benefits for the resources being protected. There can also be unintended consequences for other parts of the ecosystem, especially in complex food webs. In making decisions managers generally have to rely on qualitative information collected in a piecemeal fashion. A method to assist decision making is a qualitative modelling approach using fuzzy cognitive maps, a directed graphical model related to neural networks that can take account of interactions between pests and conservation assets in complex food webs. Using all available information on relationships between native and exotic resources and consumers, we generated hypotheses about potential consequences of single‐species and multi‐species pest control on the long‐term equilibrium abundances of other biotic components of an ecosystem. We applied the model to a dryland ecosystem in New Zealand because we had good information on its trophic structure, but the information on the strength of species interactions was imprecise. Our model suggested that pest control is unlikely to significantly boost native invertebrates and lizards in this ecosystem, suggesting that other forms of management may be required for these groups. Most of the pest control regimes tested resulted in greater abundances of at least one other pest species, which could potentially lead to other management problems. Some of the predictions were unexpected, such as more birds resulting from possum and mouse control. We also modelled the effects of an increase in invasive rabbits, which led to unexpected declines of stoats, weasels, mice and possums. These unexpected outcomes resulted from complex indirect pathways in the food web. Fuzzy cognitive maps allow rapid construction of prototype models of complex food webs using a wide range of data and expert opinion. Their utility lies in providing direction for future monitoring efforts and generating hypotheses that can be tested with field experiments.     

Incorporation of Precursors into Toxoplasma DNA

SYNOPSIS. DNA synthesis of Toxoplasma gondii differs from that of other obligate intracellular parasites in that the parasite can synthesize DNA independently of the host cell and can incorporate preformed pyrimidines as well as pyrimidine precursors. However, pyrimidine precursors such as orotic acid are preferentially utilized over preformed pyrimidines such as thymidine. There is little apparent utilization of purine precursors.     

Oppositional responses to host density in Aphytis holoxanthus (Hymenoptera: Aphefinidae), an efficient gregarious parasite

Abstract. 1. Ovipositional responses of an efficient gregarious ectoparasite ( Aphytis holoxanthus ) to increasing densities of its host (the Florida red scale, Chrysomphalus aonidum , Homoptera: Diaspididae) were studied in a laboratory system.
2. The female parasite may lay one to several eggs at each encounter with a host.
3. As host density increased, the number of eggs laid by the female parasite during the experimental period increased at a decreasing rate. This type of functional response resulted in less parasitism at higher host densities.
4. As host density increased, the number of eggs laid per encounter decreased. This behavioural response partially compensated for the decrease in parasitism.     

The first vespiform tineid moth (Lepidoptera: Tineidae)

Abstract Vespitinea gurkharum gen. et sp.n. is described from specimens reared from a bracket-fungus ( Ganoderma - Polyporaceae) from lowland rain-forest in Brunei. This striking wasp-like moth is suggested to be a Batesian mimic of species of Vespidae and Pompilidae (Hymenoptera) and the first example of this mimicry type recorded from the Tineoidea. Abdominal, eye and wing-coupling modifications suggest that it is diurnal and a behavioural mimic. The systematic position of Vespitinea is discussed with reference to biology and adult and larval morphology.     

Scanning electron microscope study of the palar pegs of three species of Corixidae (Hemiptera)

Scanning electron microscope studies were performed on the palar pegs of male forelegs of Trichocorixa sexcincta, Sigara alternata and Hesperocorixa interrupta. The studies showed the pegs to be basically conical and chevron-ridged, with a wide base that tapered of to a narrow apex. Clear species differences were apparent with respect to the size of the peg, the number of ridges on an individual peg, and the number and arrangement of the pegs on the pala. The possible behavioural and evolutionary significance of the palar pegs is discussed in relation to mating.