IMPACT OF DIFFERENCES IN TASTE TEST RATINGS ON THE CONSUMPTION OF MILK IN BOTH A LABORATORY AND A FOODSERVICE SETTING1

The objective of this study was to observe the impact of a perceptible difference in the liking of milk on consumption of the milk in both laboratory and cafeteria settings. We produced milk with no flavor defects and milk with a light oxidized flavor. The defect-free milk scored about 1 point higher than the off-flavored milk on a 9-point hedonic scale. We placed the same two milk products in the milk dispenser in a dormitory cafeteria for a total of 32 dinner meals and measured the amount of milk consumed. A subset of subjects from the cafeteria population also consumed the milks in a laboratory consumption test. In a second laboratory consumption test a different group of subjects consumed the two milks. The liking difference had no impact on consumption in the dormitory food service setting and either no impact or a small impact on consumption in a laboratory setting.     

A novel indirect defence in Brassicaceae: Structure and function of extrafloral nectaries in Brassica juncea

While nectaries are commonly found in flowers, some plants also form extrafloral nectaries on stems or leaves. For the first time in the family Brassicaceae, here we report extrafloral nectaries in Brassica juncea. The extrafloral nectar (EFN) was secreted from previously amorphic sites on stems, flowering stalks and leaf axils from the onset of flowering until silique formation. Transverse sections at the point of nectar secretion revealed a pocket‐like structure whose opening was surrounded by modified stomatal guard cells. The EFN droplets were viscous and up to 50% of the total weight was sugars, 97% of which was sucrose in the five varieties of B. juncea examined. Threonine, glutamine, arginine and glutamate were the most abundant amino acids. EFN droplets also contained glucosinolates, mainly gluconapin and sinigrin. Nectar secretion was increased when the plants were damaged by chewing above‐ and belowground herbivores and sap‐sucking aphids. Parasitoids of each herbivore species were tested for their preference, of which three parasitoids preferred EFN and sucrose solutions over water. Moreover, the survival and fecundity of parasitoids were positively affected by feeding on EFN. We conclude that EFN production in B. juncea may contribute to the indirect defence of this plant species.     

Nitrous oxide emissions from a cropped soil in a semi-arid climate

Understanding nitrous oxide (N₂O) emissions from agricultural soils in semi‐arid regions is required to better understand global terrestrial N₂O losses. Nitrous oxide emissions were measured from a rain‐fed, cropped soil in a semi‐arid region of south‐western Australia for one year on a sub‐daily basis. The site included N‐fertilized (100 kg N ha^?1 yr^?1) and nonfertilized plots. Emissions were measured using soil chambers connected to a fully automated system that measured N₂O using gas chromatography. Daily N₂O emissions were low (?1.8 to 7.3 g N₂O‐N ha^?1 day^?1) and culminated in an annual loss of 0.11 kg N₂O‐N ha^?1 from N‐fertilized soil and 0.09 kg N₂O‐N ha^?1 from nonfertilized soil. Over half (55%) the annual N₂O emission occurred from both N treatments when the soil was fallow, following a series of summer rainfall events. At this time of the year, conditions were conducive for soil microbial N₂O production: elevated soil water content, available N, soil temperatures generally >25 °C and no active plant growth. The proportion of N fertilizer emitted as N₂O in 1 year, after correction for the ‘background’ emission (no N fertilizer applied), was 0.02%. The emission factor reported in this study was 60 times lower than the IPCC default value for the application of synthetic fertilizers to land (1.25%), suggesting that the default may not be suitable for cropped soils in semi‐arid regions. Applying N fertilizer did not significantly increase the annual N₂O emission, demonstrating that a proportion of N₂O emitted from agricultural soils may not be directly derived from the application of N fertilizer. ‘Background’ emissions, resulting from other agricultural practices, need to be accounted for if we are to fully assess the impact of agriculture in semi‐arid regions on global terrestrial N₂O emissions.     

Novel tetranucleotide microsatellite markers from the Del Norte salamander (Plethodon elongatus) with application to its sister species the Siskiyou Mountain salamander (P. stormi)

Eleven tetranucleotide microsatellite loci were developed for the Del Norte salamander (Plethodon elongatus). The loci were variably polymorphic, ranging from two to 20 alleles per locus, with expected heterozygosities ranging from 0.07 to 0.86. The loci also amplified in a congener, the Siskiyou Mountain salamander (P. stormi). The microsatellite loci will be used to assess the utility of highly polymorphic markers to assay within‐ and between‐species differentiation between these two closely related species.     

A New Pathogen,Microsporidium itiiti n. sp. (Microsporida), from the Argentine Stem Weevil,Listronotus bonariensis (Coleoptera,Curculionidae)1

A new species of microsporidium (phylum Microspora) infecting the Argentine stem weevil, Listronotus bonariensis (Kuschel. 1955), is described on the basis of light and electron microscope observations. It has the following characteristics: nuclei always isolated; meronts spherical and sporonts ribbon-shaped, with variable numbers of nuclei; sporogony within a vacuole which is bounded by a thin membrane that usually breaks down before uninucleate spores mature; occasionally parts of the membrane remain so that clusters of variable numbers of spores may be seen in light microscopic preparations. Spores measure 2.5 × 1.4 μm (fresh) and development occurs mainly in the midgut, but also in the epidermis, fat body, muscle, and ovaries.     

Corals from an Early Jurassic coral reef in British Columbia: refuge on an oceanic island reef

An Early Jurassic (Sinemurian) reef in the Telkawa Range, British Columbia Canada, yields coral species previously known from Morocco, Great Britain, Italy, Peru, and Chile. The principal constructional coral, Phacelostylophyllum rugosum (Laube), known from the Upper Triassic Dolomite Alps in northern Italy, is a holdover species. This coral survived the mass extinctions of the end-Triassic without leaving any other Jurassic records outside Canada. Other corals from the Telkwa reef include Stylophyllopsis victoriae (Duncan) and Actinastraea minima Beauvais known from Jurassic rocks of the Tethys. Closely related corals, Phacelostylophyllum chocolatensis (Wells) and Actinastraea plana (Duncan), are from southern Peru. The paleogeographic Occurrence of the Canadian reef in the volcanic terrane of Stikinia supports the contention that volcanic islands in distant outposts of the ancient Pacific served as refugia. In the aftermath of the end-Triassic reef decimation affecting the Tethys, corals and reef-building activities continued on ancient islands of the ancestral Pacific. The Hispanic Corridor, connecting the western Tethys with the western Pacific, may have played an important role during Sinemurian time. ***Reef; corals, Triassic, Jurassic, extinctions, paleobiogeography.     

A learning-related variation in electroantennogram responses of a parasitic wasp

ABSTRACT Odour responses of parasitic insects, in search of their hosts, can change due to experience. Leptopilina heterotoma (Thomson) (Hymenoptera; Eucoilidae), a parasitic wasp of drosophilid larvae, is known to alter its preference for odours emanating from host food substrates through learning. These kinds of behavioural modifications in insects are assumed to be the result of complex processes in the brain. The results presented in this report, however, suggest that this learning-related behavioural variation is not restricted to brain processes but that it involves changes in sensitivity of olfactory receptor neurones.     

Historical biogeography and ecology of a Continental Antarctic mite genus, Maudheimia (Acari, Oribatida): evidence for a Gondwanan origin and Pliocene-Pleistocene speciation

Of the eight genera (30 species) of extant Acari in Continental (= East) Antarctica, the genus Maudheimia Dalenius & Wilson, 1958 (Oribatida; Maudheimiidae) is uniquely endemic. A Gondwanan origin is proposed for the genus based on antiquity, inferred from endemism, a widespread distribution throughout Continental Antarctica and a limited dispersal capacity. Adaptation for a high montane epilithic existence, a necessity for the origination and long-term persistence in Antarctica, is inferred from the life history, physiology and ecology of Maudheimia. Phylogenetic analysis placed all four Maudheimia species in a single (generic) clade with the following structure (M. pelronia Wallwork, 1962 (M. tanngardenensis Coctzee, 1997 (M. manhalli Coetzee, 1997 (M. wilsoni Dalenius & Wilson, 1958)))). Geographical distributions of the Maudheimia species, in relation to their phylogenetic relationships, support the hypothesis that post-Gondwanan speciation occurred as a consequence of isolation during glaciation of Antarctica.