Improvement of persistence and yield of Italian ryegrass (Lolium multiflorum) through pesticide use

The present two field experiments, involving plots of Italian ryegrass sown in 1976, 1980 and 1984 confirmed results of earlier work in which the yield and persistence of Italian ryegrass was greatly increased by the application of pesticide. A range of pesticide treatments were used. The responses to application of permethrin applied three times per year average 8% for the three years of the first experiment and 5% for the five years of the second experiment. Such responses appeared cost-effective, but the overall environmental impact of such applications is not known.     

Determination of traits associated with leafhopper (Empoasca fabae and Empoasca kraemeri) resistance and dissection of leafhopper damage symptoms in the common bean (Phaseolus vulgaris)

The typical presentation of potato leafhopper injury in beans includes necrosis at the leaf margins (leaf burn or hopperburn), and downward curling or “cupping” of the leaves. To evaluate potato leafhopper damage a visual score that combines the overall severity of leaf burn, leaf curling and stunting symptoms is usually used. Nonetheless, it may be useful to evaluate these symptoms separately since they may be the result of separate mechanisms of damage, controlled by separate genes. A population of 108 recombinant inbred lines (RILs), derived from a cross between a leafhopper‐susceptible Ontario cultivar (Berna) and a resistant line (EMP 419) were scored for injury after natural infestation with Empoasca fabae in Canada and Empoasca kraemeri in Colombia. Leaf burn and leaf curl were significantly rank‐correlated (0.37–0.74, P<0.001) in all environments. However, several RILs consistently exhibited high scores for leaf curl but low values for leaf burn, which suggests that genetic dissection of these characters may be possible. Indeterminate growth habit was associated with slightly lower damage scores in Colombia and Ontario, Canada (P<0.05) while white‐seeded lines had lower damage scores in Colombia (P<0.05). The resistant parental line had significantly lower nymph counts than did the susceptible parent. A positive relationship between damage scores and nymph counts was also observed in the F₃ families and the F_5:6 RILs.     

Some Properties of an Acid Phosphatase Isolated from the Seed Coats of Developing Pea Seeds

An acid phosphatase (EC 3 1 3 2)isolated from the seed-coatsof developing pea seeds was estimated to have MW 30000 by gelfiltration on Sephadex G-75 It was shown to act on a broad spectrumof physiological substrates, the most preferred being ß-glycerophosphate,3-phosphoglycerate and ADP, wich all showed rates of about halfthe maximum rate shown with p-nitrophenyl phosphate (p-NPP)Another model substrate frequently used in enzyme localizationstudies, -naphthyl acid phosphate, was hydrolysed at about 30% of the rate shown with p-NPP This acid phosphatase was enhancedor stabilized by the chelators EDTA and 1, 10-phenanthrolme,unaffected by Mg²⁺ and N-ethyl maleimide, but strongly inhibitedby Zn²⁺ and F^– Both oxidized and reduced glutathione werewithout effect at low concentration and slightly inhibitoryat high concentration (15 mm) Thiol groups are clearly not involvedin regulating the activity of this acid phosphatase, a featurewhich distinguishes it from acid phosphatases from several otherplant species. Pisum sativum L, pea, acid phosphatase, seed-coats, seed development     

The role of forest maturation in causing the decline of Black Grouse Tetrao tetrix

Black Grouse Tetrao tetrix in Britain have declined through the 20th century, and most birds are now in Scotland. Many causes for this decline have been suggested, notably agricultural intensification, increased grazing levels and moorland afforestation. We examine habitat correlates of Black Grouse distribution and population change from a 700-km² area in the core of the Scottish range, where the numbers of lekking male Black Grouse declined by an estimated 70% to 270 between 1990 and 2002. Habitat data were derived from satellite imagery, in combination with map and field-collected data. Lek occurrence, lek size and changes in lek size were all correlated with forest structure, either positively with the amount of pre-thicket forest cover, or negatively with closed canopy cover. Additional effects of the cover of grass moor and dry heath suggest that Black Grouse are most likely to occur where moorland comprises Heather Calluna vulgaris and grass mosaics. Analysis of the change in Black Grouse abundance within 1.5 km of discrete forest blocks suggests that forest maturation, which has been the dominant habitat change during the course of the study, alone accounts for 58–78% of the decline. Given the close association of Black Grouse and the occurrence of woodland (and particularly conifer plantation) throughout much of their British range, these findings can be used to inform the design of management schemes for the recovery of Black Grouse.     

Validation of a Field Technique and Characterization of Fecal Glucocorticoid Metabolite Analysis in Wild Chimpanzees (Pan troglodytes)

Monitoring adrenocortical activity in wild primate populations is critical, given the well‐documented relationship between stress, health, and reproduction. Although many primate studies have quantified fecal glucocorticoid metabolite (FGM) concentrations, it is imperative that researchers validate their method for each species. Here, we describe and validate a technique for field extraction and storage of FGMs in wild chimpanzees (Pan troglodytes). Our method circumvents many of the logistical challenges associated with field studies while yielding similar results to a commonly used laboratory method. We further validate that our method accurately reflects stress physiology using an adrenocorticotropic hormone challenge in a captive chimpanzee and an FGM peak at parturition in a wild subject. Finally, we quantify circadian patterns for FGMs for the first time in this species. Understanding these patterns may allow researchers to directly link specific events with the stress response. Am. J. Primatol. 75:57‐64, 2013. © 2012 Wiley Periodicals, Inc.     

Life‐history and ecological correlates of decline and extinction in the endemic Australian frog fauna

Abstract Frog populations are rapidly disappearing throughout the world. An important issue for ecologists to resolve is why some frog species are more susceptible to decline than others. Here, we performed a comparative study of the endemic Australian frog fauna to determine whether the life history and ecology of declining species have predisposed them to extinction. Decline was consistently found to be correlated with geographical range size across contemporary species and in analyses based on phylogenetically independent contrasts (PICs). Species with narrow geographical ranges have been disproportionately more susceptible to decline. Across species, decline was also correlated with large body size and a high proportion of the geographical range overlapping with the distribution of cane toads and landscape stress (e.g. land clearing). We show that with the exception of range size, however, correlates of decline across species are underpinned by a small number of evolutionary events. Hence, the suite of traits that correlate with decline in the cross‐species analysis is only relevant to a small number of clades. We also found that clutch size, testes mass, ova size and distributional overlap with feral pigs were not significantly related to decline. In the ongoing search for life‐history and ecological correlates of decline and extinction, our results highlight the importance of performing analyses across contemporary species and using PICs.     

Confirmation of Ancient Polyploidy in Dahlia (Asteraceae) Species using Genomic In Situ Hybridization

The successful production of interspecific hybrids between membersof the dysploid chromosome series inDahlia offers a unique opportunityto investigate chromosome evolution. Analysis of meiotic metaphaseI in these hybrids using genomic in situ hybridization (GISH)has shown that pairing occurs both between and within parentalgenomes. These results have provided clear evidence for theallotetraploid origin of Dahlia species with 2n=32 and suggeststhat species with 2n=34 and 2n=36 have also arisen via allopolyploidy.A bivalent promoting mechanism proposed for species with 2n=32also appears to be present in Dahlia species with 2n=34 and2n=36 .Copyright 1999 Annals of Botany Company Dahlia , GISH, dysploidy, chromosome pairing, karyotype analysis, polyploidy.     

Improvement of the 15N dilution method for estimation of absorption of NOx by plants supplied with 15N-labelled fertilizer

To develop further the methods for estimation of NOx absorption by plants supplied with ¹⁵N-labelled fertilizer, we proposed a new calculation method, total N fixed method (TNF), and compared with the ¹⁵N dilution method and the classical mass balance method (MB).
Hydroponically grown soybean plants were supplied with ¹⁵N-labelled nitrate and exposed to 200–250 nl l⁻¹ NO₂ for 7 d. The proportions of the N derived from NO₂ to total N in exposed plants were estimated by the three methods.
The reported rates of NO₂ absorption by several plant species, estimated by the ¹⁵N dilution method, were recalculated using the TNF method. The results of the two methods were compared and showed that: (1) The ¹⁵N dilution method overestimated the content of NO₂-N in exposed plants compared with the MB method whilst the TNF method produced estimations of NO₂-N closer to those by the MB method when the plants were supplied with 5 m M nitrate. (2) The differences in estimations between the MB method and either the ¹⁵N dilution method or the TNF method increased with decreasing supply of ¹⁵N-labelled nitrate to roots.     

Assessment of Canada Lynx Research and Conservation Needs in the Southern Range: Another Kick at the Cat

Abstract The ecology of Canada lynx (Lynx canadensis) and their main prey, snowshoe hares (Lepus americanus), is poorly understood in southern Canada and the contiguous United States compared to the boreal forest of Canada and Alaska, USA, where both species are well studied. However, given recent listing of lynx under the Endangered Species Act, accurate understanding of lynx and snowshoe hare ecology and conservation requirements in the United States is a high priority. We critically examined unchallenged perceptions and important research needs related to lynx and hare ecology and conservation at the southern extent of their range. Contrary to popular dogma, lynx do not require old-growth forest for denning, but further research on lynx and hare use of fragmented landscapes at lower latitudes is required. The contention that southern lynx are subject to higher interference or exploitative competition compared to their northern counterparts remains without strong empirical support. Lynx rely more on red squirrels (Tamiasciurus hudsonicus) and possibly other alternate prey at lower latitudes, but hares are the predominant food type for lynx across their range. Southern lynx and hare populations do not exhibit periodic cyclicity, but harvest statistics suggest that lynx abundance in the southern range is highly variable, implying that numerical fluctuations likely are fueled by immigration from Canada. Southern lynx population viability in the absence of ingress is suspect and thus maintaining connectivity with northern areas of occupancy should be a priority. Successful conservation of lynx populations in the contiguous United States will require 1) improved understanding of lynx population and habitat ecology at lower latitudes, 2) protection and management of large tracts of lynx and snowshoe hare habitat, and 3) ensured connectivity between lynx populations at the core and periphery of the species' range. However, in light of the numerous challenges facing conservation of populations of many species at their southern distributional limit, the long-term prognosis for lynx in the southern range currently is uncertain.