APPLICATION OF THE ECONOMIC THRESHOLD FOR INTERSEASONAL PEST CONTROL

We show how an interseasonal pest control problem can be simplified to enable an intraseasonal model to be empirically applied, extending the range of application of the intraseasonal model. Three alternative economic thresholds are compared. The optimal solution requires repeated computations by the farmer to compute the profit maximizing dose, with a corresponding threshold, for each pest infestation. Two alternative decision rules require a single computation by the farmer for the threshold and dosage rate. An empirical illustration shows that, relative to the optimal solution which is computationally burdensome to the farmer, little net revenue is lost by using one of the thresholds based upon a simpler decision rule.Farm Management,

ECONOMIC THRESHOLDS UNDER UNCERTAINTY WITH APPLICATION TO CORN NEMATODE MANAGEMENT

An economic threshold of agricultural pest management is derived. Results provide a method for researchers to use in making improved pest control recommendations to farmers without farm level decision-making. An empirical illustration for lesion nematode management in irrigated corn is given and directions for further research are indicated.Crop Production/Industries, Risk and Uncertainty,

Peramorphosis, an evolutionary developmental mechanism in neotropical bat skull diversity

Background The neotropical leaf‐nosed bats (Chiroptera, Phyllostomidae) are an ecologically diverse group of mammals with distinctive morphological adaptations associated with specialized modes of feeding. The dramatic skull shape changes between related species result from changes in the craniofacial development process, which brings into focus the nature of the underlying evolutionary developmental processes. Results In this study, we use three‐dimensional geometric morphometrics to describe, quantify, and compare morphological modifications unfolding during evolution and development of phyllostomid bats. We examine how changes in development of the cranium may contribute to the evolution of the bat craniofacial skeleton. Comparisons of ontogenetic trajectories to evolutionary trajectories reveal two separate evolutionary developmental growth processes contributing to modifications in skull morphogenesis: acceleration and hypermorphosis. Conclusion These findings are consistent with a role for peramorphosis, a form of heterochrony, in the evolution of bat dietary specialists

The Neutron Electric Dipole Moment and CP-violating Couplings in the Supersymmetric Standard Model without R-parity

We analyze the neutron electric dipole moment (EDM) in the Minimal Supersymmetric Model with explicit R-parity violating terms. The leading contribution to the EDM occurs at the 2-loop level and is dominated by the chromoelectric dipole moments of quarks, assuming there is no tree-level mixings between sleptons and Higgs bosons or between leptons and gauginos. Based on the experimental constraint on the neutron EDM, we set limits on the imaginary parts of complex couplings ${\lambda'}_{ijk}$ and ${\lambda}_{ijk}$ due to the virtual b-loop or tau-loop.Comment: final manuscript to appear in Phys. Rev. D, 15 pages, latex, 4 figures include

On the origin of spaces: morphometric foundations of urban form evolution

The modern discipline of urban morphology gives us a ground for the comparative analysis of cities, which increasingly includes specific quantitative elements. In this paper, we make a further step forward towards the definition of a general method for the classification of urban form. We draw from morphometrics and taxonomy in life sciences to propose such method, which we name ‘urban morphometrics’. We then test it on a unit of the urban landscape named ‘Sanctuary Area’ (SA), explored in 45 cities whose origins span four historic time periods: Historic (medieval), Industrial (19th century), New Towns (post-WWII, high-rise) and Sprawl (post-WWII, low-rise). We describe each SA through 207 physical dimensions and then use these to discover features that discriminate them among the four temporal groups. Nine dimensions emerge as sufficient to correctly classify 90% of the urban settings by their historic origins. These nine attributes largely identify an area's ‘visible identity’ as reflected by three characteristics: (1) block perimeterness, or the way buildings define the street-edge; (2) building coverage, or the way buildings cover the land and (3) regular plot coverage, or the extent to which blocks are made of plots that have main access from a street. Hierarchical cluster analysis utilising only the nine key variables nearly perfectly clusters each SA according to its historic origin; moreover, the resulting dendrogram shows, just after WWII, the first ‘bifurcation’ of urban history, with the emergence of the modern city as a new ‘species’ of urban form. With ‘urban morphometrics’ we hope to extend urban morphological research and contribute to understanding the way cities evolve

DNA Barcoding Reveals Cryptic Diversity in Lumbricus terrestris L., 1758 (Clitellata): Resurrection of L. herculeus (Savigny, 1826)

The widely studied and invasive earthworm, Lumbricus terrestris L., 1758 has been the subject of nomenclatural debate for many years. However these disputes were not based on suspicions of heterogeneity, but rather on the descriptions and nomenclatural acts associated with the species name. Large numbers of DNA barcode sequences of the cytochrome oxidase I obtained for nominal L. terrestris and six congeneric species reveal that there are two distinct lineages within nominal L. terrestris. One of those lineages contains the Swedish population from which the name-bearing specimen of L. terrestris was obtained. The other contains the population from which the syntype series of Enterion herculeum Savigny, 1826 was collected. In both cases modern and old representatives yielded barcode sequences allowing us to clearly establish that these are two distinct species, as different from one another as any other pair of congeners in our data set. The two are morphologically indistinguishable, except by overlapping size-related characters. We have designated a new neotype for L. terrestris. The newly designated neotype and a syntype of L. herculeus yielded DNA adequate for sequencing part of the cytochrome oxidase I gene (COI). The sequence data make possible the objective determination of the identities of earthworms morphologically identical to L. terrestris and L. herculeus, regardless of body size and segment number. Past work on nominal L. terrestris could have been on either or both species, although L. herculeus has yet to be found outside of Europe

An Evaluation of Putative Sympatric Speciation within Limnanthes (Limnanthaceae)

Limnanthes floccosa ssp. floccosa and L. floccosa ssp. grandiflora are two of five subspecies within Limnanthes floccosa endemic to vernal pools in southern Oregon and northern California. Three seasons of monitoring natural populations have quantified that L. floccosa ssp. grandiflora is always found growing sympatrically with L. floccosa ssp. floccosa and that their flowering times overlap considerably. Despite their subspecific rank within the same species crossing experiments have confirmed that their F1 hybrids are sterile. An analysis of twelve microsatellite markers, with unique alleles in each taxon, also shows exceedingly low levels of gene flow between populations of the two subspecies. Due to the lack of previous phylogenetic resolution among L. floccosa subspecies, we used Illumina next generation sequencing to identify single nucleotide polymorphisms from genomic DNA libraries of L. floccosa ssp. floccosa and L. floccosa ssp. grandiflora. These data were used to identify single nucleotide polymorphisms in the chloroplast, mitochondrial, and nuclear genomes. From these variable loci, a total of 2772 bp was obtained using Sanger sequencing of ten individuals representing all subspecies of L. floccosa and an outgroup. The resulting phylogenetic reconstruction was fully resolved. Our results indicate that although L. floccosa ssp. floccosa and L. floccosa ssp. grandiflora are closely related, they are not sister taxa and therefore likely did not diverge as a result of a sympatric speciation event

An Inhibitory Sex Pheromone Tastes Bitter for Drosophila Males

Sexual behavior requires animals to distinguish between the sexes and to respond appropriately to each of them. In Drosophila melanogaster, as in many insects, cuticular hydrocarbons are thought to be involved in sex recognition and in mating behavior, but there is no direct neuronal evidence of their pheromonal effect. Using behavioral and electrophysiological measures of responses to natural and synthetic compounds, we show that Z-7-tricosene, a Drosophila male cuticular hydrocarbon, acts as a sex pheromone and inhibits male-male courtship. These data provide the first direct demonstration that an insect cuticular hydrocarbon is detected as a sex pheromone. Intriguingly, we show that a particular type of gustatory neurons of the labial palps respond both to Z-7-tricosene and to bitter stimuli. Cross-adaptation between Z-7-tricosene and bitter stimuli further indicates that these two very different substances are processed by the same neural pathways. Furthermore, the two substances induced similar behavioral responses both in courtship and feeding tests. We conclude that the inhibitory pheromone tastes bitter to the fly