A screen of worldwide wheat cultivars for hydroxamic acid levels and aphid antixenosis

In a screen of seedlings of a worldwide range of 47 cultivars of Triticum (mainly T. aestivum) the concentration of the hydroxamic acid DIMBOA ranged between 1 and 8 mmol/kg fresh wt. In a bioassay in which alatae of the aphid Sitobion avenae were released among replicated test seedlings, there were highly significant correlations between aphid ‘preference’ and DIMBOA levels in the seedlings. The value of these results in work leading to the production of aphid-resistant cultivars is discussed.     

Aspects of insect chemical ecology: exploitation of reception and detection as tools for deception of pests and beneficial insects

Empirical exploitation of insect reception and detection at the peripheral neurosensory level has been extremely valuable for identifying pheromones and other semiochemicals, mainly by electroantennogram or single cell preparations coupled with capillary gas chromatography. Differential sensitivity to semiochemicals at the single‐cell level has allowed the identification of some of the most active semiochemicals relating to host location and, more importantly, to the avoidance of nonhosts. However, in terms of molecular recognition, there is still a considerable gap in understanding the detection of particular molecules and their discrimination from closely‐related chemical structures. New approaches will be needed to understand the processes of molecular recognition more precisely. Nevertheless, from electrophysiological studies to the most advanced molecular techniques, it has been possible to identify semiochemicals for the deception of pests in their quest to find plant and animal hosts, as well as mates. Even the deception of insects antagonistic to pests, particularly parasitoids, can now be exploited for managing pests in more sustainable systems. Successes in exploiting insect semiochemicals in the interests of better agriculture and animal husbandry are exemplified, and potential new ways of learning more about reception and detection for deception are discussed. This takes the subject beyond the management of pest and beneficial insects to wider commercial and social opportunities.     

Granulocyte-Macrophage Colony-Stimulating Factor is a Growth-Factor for Promastigotes of Leishmania mexicana amazonensis

ABSTRACT. In this paper we show that murine lung conditioned medium (LCM) displays, in addition to its already described colony-stimulating activity on bone marrow cells, a potent growth-stimulating activity on promastigotes of Leishmania mexicana amazonensis . Immunoprecipitation of LCM with an antibody specific for murine granulocyte-macrophage colony stimulating factor (GM-CSF) abrogates both activities, indicating that the leishmanial growth-promoting activity is due to the presence of GM-CSF on LCM. Furthermore, recombinant GM-CSF (rGM-CSF) added to the culture medium or to the immunoprecipitated LCM is able to respectively induce or to partially recover the growth-promoting activity of the LCM. Sequential in vitro passages of the parasite induces a progressive loss of sensitivity to the growth-factor. Parasite forms recently collected from lesions are significantly more responsive to the growth-factor than forms already adapted to grow in culture. Since it has been shown that several different microorganisms display receptors for vertebrate-like hormones and that GM-CSF is able to enhance a cutaneous leishmanial lesion, our results permit us to raise the hypothesis that a direct interaction between a host-derived hormone and a pathogenic microorganism can be of importance in defining the fate of an infection. The fact that GM-CSF is produced by cells that actively participate in a leishmanial infection (T-lymphocytes and macrophages) reinforces our hypothesis.     

Effects of some surfactant fungicides on Rhizobium trtfolii and its symbiotic relationship with white clover

Effects of the surfactant apple mildew eradicants Manoxol OT, Alk 3, Triton X45, PP 222, Ethylan CP, Hyamine 3500, Aromox DMMCDW and Aromox C12W on growth and respiration of R. trifolii in vitro and on its symbiotic nitrogen fixation in association with white clover were measured. Most treatments reduced growth up to 8 wk; after 12 wk plant weight and nitrogenase activity were significantly reduced (P = 0.01) by Triton X45, Manoxol OT and PP 222 at concentrations of 1000, 2500 and 5000 μg/gram of soil respectively. Electron microscopy showed that bacteroids in root nodules where nitrogen fixation was inhibited had contracted away from the host membrane leaving an intracellular space. Damage to the bacteroid membrane was apparent. Surfactants had no demonstrable effect on adhesion of the bacteria to root hairs. In apple orchards run-off of surfactant fungicides, applied to apple trees at the recommended rates is unlikely to have adverse effects on Rhizobium nodulated white clover.     

Modelling of landscape variables at multiple extents to predict fine sediments and suitable habitat for Tubifex tubifex in a stream system

1. Aggregations of fine sediments are a suitable proxy for the presence and abundance of Tubifex tubifex, one of the obligate hosts in the parasitic life cycle that causes salmonid whirling disease (Myxobolus cerebralis). 2. To determine and evaluate practical approaches to predict fine sediments (<2 mm diameter) that could support Tubifex spp. aggregations, we measured habitat features in a catchment with field measures and metrics derived from digital data sets and geospatial tools at three different spatial extents (m²) within a hierarchical structure. 3. We used linear mixed models to test plausible candidate models that best explained the presence of fine sediments measured in stream surveys with metrics from several spatial extents. 4. The percent slow water habitat measured at the finest extent provided the best model to predict the likely presence of fine sediments. The most influential models to predict fine sediments using landscape metrics measured at broader extents included variables that measure the percentage land cover in conifer or agriculture, specifically, decreases in conifer cover and increases in agriculture. 5. The overall best‐fitting model of the presence of fine sediments in a stream reach combined variables measured and operating at different spatial extents. 6. Landscape features modelled within a hierarchical framework may be useful tools to evaluate and prioritise areas with fine sediments that may be at risk of infection by Myxobolus cerebralis.     

The evolution of conspicuous facultative mimicry in octopuses: an example of secondary adaptation?

The ‘Mimic Octopus’Thaumoctopus mimicus Norman & Hochberg, 2005 exhibits a conspicuous primary defence mechanism (high‐contrast colour pattern during ‘flatfish swimming’) that may involve facultative imperfect mimicry of conspicuous and/or inconspicuous models, both toxic and non‐toxic (Soleidae and Bothidae). Here, we examine relationships between behavioural and morphological elements of conspicuous flatfish swimming in extant octopodids (Cephalopoda: Octopodidae), and reconstructed ancestral states, to examine potential influences on the evolution of this rare defence mechanism. We address the order of trait distribution to explore whether conspicuous flatfish swimming may be an exaptation that usurps a previously evolved form of locomotion for a new purpose. Contrary to our predictions, based on the relationships we examined, flatfish swimming appears to have evolved concurrently with extremely long arms, in a clade of sand‐dwelling species. The conspicuous body colour pattern displayed by swimming T. mimicus may represent a secondary adaptation potentially allowing for mimicry of a toxic sole, improved disruptive coloration, and/or aposematic coloration. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 68–77.     

New data on molluscs and their shell microstructures from the Middle Cambrian Gowers Formation, Australia

Abstract: Numerous new cases of preserved shell microstructure were discovered in molluscs from the Middle Cambrian Gowers Formation (Ptychagnostus atavus/Peronopsis opimus Zone, Floran Stage) in the Georgina Basin, Australia. The new data provide further evidence that, by the Middle Cambrian, molluscan shell microstructures were diverse, and many molluscs had a complex shell with multiple types of shell microstructure. In addition, many new occurrences of laminar microstructures are described herein. For many, the nature of these laminar microstructures is not known, but in three species the microstructure is foliated calcite, and in at least two the microstructure is more likely to have been calcitic semi‐nacre, a type of microstructure known in brachiopods and bryozoans but unknown in modern molluscs. This commonality among these three closely related lophotrochozoans underscores a similar mechanism of biomineralization. Moreover, these observations suggest a prevalence of calcite‐shelled lineages among molluscs from the Middle Cambrian, a time of calcite seas. In addition, the broad occurrence of laminar, nacre‐like microstructures in many of these fossils reveals how widespread these strong (fracture‐resistant) microstructures were in Middle Cambrian molluscs. Additionally, a few specimens of Yochelcionella preserve imprints of a bilaterally symmetrical pair of muscle scars. New taxa described here include Corystos thorntoniensis gen. et sp. nov., Yochelcionella snorkorum sp. nov., Yochelcionella saginata sp. nov., and Anhuiconus? agrenon sp. nov.     

Carbon steady-state model of the planktonic food web of Lake Biwa, Japan

1. A steady‐state model of carbon flows was developed to describe the summer planktonic food web in the surface mixed‐layer of the North Basin in Lake Biwa, Japan. This model synthesised results from numerous studies on the plankton of Lake Biwa. 2. An inverse analysis procedure was used to estimate missing flow values in a manner consistent with known information. Network analysis was applied to characterise emergent properties of the resulting food web. 3. The system strongly relied on flows related to detrital particles. Whereas primary production was mainly by phytoplankton >20 μm, microzooplankton were active and mainly ingested detritus and bacteria. 4. The main emergent property of the system was strong recycling, through either direct ingestion of non‐living material by zooplankton, or ingestion of bacteria after degradation of detritus to release dissolved organic carbon.     

A comparison of habitat use, morphology, clinging performance and escape behaviour among two divergent green anole lizard (Anolis carolinensis) populations

We measured available and actual habitat use, morphology, escape behaviour and clinging ability in a large sample ( N  = 242) of green anoles, Anolis carolinensis , in a habitat consisting primarily of segregated dense clumps of broad leaves, Aspidistra elatior (Tulane University campus, LA) to compare against similar data collected previously from a more typical habitat c. 30 km away, consisting of continuous strands of bushes and trees (Good Hope Field, St. Charles Parish, LA). At Tulane the anoles perched primarily on the broad, smooth leaves of broad leaves, whereas in Good Hope Field (GHF) they predominantly perched on branches and tree trunks. The two populations differed significantly in morphology. In Tulane, the anoles tended to have shorter distal hindlimb elements, longer forelimb elements, and were more 'slender' than those at GHF. A comparison of escape behaviour showed population and sex differences. In both populations, females had significantly longer approach distances (i.e. were more 'wary') than males. These distances were, in addition, significantly longer at GHF than at Tulane for both sexes; this may be due to the potentially higher diversity and abundance of predators at GHF, although habituation to humans may also play a role. Anoles at Tulane had significantly larger toepads and higher clinging abilities than those at GHF. The enhanced clinging abilities of anoles at Tulane may have arisen due to their propensity to use smooth leaves as their primary substrate. Overall, our data reveal substantial ecological, behavioural, morphological, and functional differences among populations, some of which may be adaptive.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 223–234.