Integrated pest management of the Mexican rice borer in Louisiana and Texas sugarcane and rice

Interactions between sugarcane, Saccharum spp., and the invasive species Mexican rice borer, Eoreuma loftini (Dyar), were evaluated in field experiments and in the greenhouse with rice, Oryza sativa L., as an additional host. By determining adult emergence holes together with percent bored internodes, a novel method for evaluating sugarcane cultivar resistance was developed. In 2001, LCP 85-384 had the greatest moth production per hectare, significantly higher (P ≤ 0.05) than HoCP 85-845. High levels of sodium and magnesium salt stress in the soil were associated with higher E. loftini injury in all cultivars except HoCP 91-555 and CP 70-321. Irrigation reduced injury in both susceptible (LCP 85-384) and resistant (HoCP 85-845) cultivars by 2.5-fold. The combination of irrigation, plant resistance, and insecticide applications of tebufenozide decreased injury from 70% bored internodes to less than 10%. Several free amino acids essential for insect development increased in sugarcane leaves under drought stressed conditions, which exacerbated E. loftini infestations. Drought stressed sugarcane was 1.8-fold more attractive based on egg masses/plant than non stressed sugarcane. Based on egg masses/plant and eggs/egg mass, cultivar LCP 85-384 was more attractive than the resistant HoCP 85-845. Egg masses were 9.2-fold more abundant on sugarcane than on rice. Oviposition on sugarcane occurred exclusively on dry leaf material, and the number of dry leaves was positively correlated with egg masses per plant. Several free amino acids essential for insect development increased in sugarcane leaves under drought stressed conditions, and were highly correlated with egg masses per plant. Rice leaves, despite being less attractive for oviposition, had higher levels of free amino acids than sugarcane. Based on boundary movement monitoring with pheromone traps, the average rate of spread from 1980 (Weslaco, TX) to 2004 (Chambers County, TX) was 23.2 km/yr. From 2000 to 2004, annual mean centroids of moth trap counts moved 29.3 km, however 95% C.I. overlapped across years. Minimizing sugarcane stress will play a major role in managing this invasive pest when it becomes established in Louisiana

Quantifying extreme behaviour in geomagnetic activity

Understanding the extremes in geomagnetic activity is an important component in understanding just how severe conditions can become in the terrestrial space environment. Extreme activity also has consequences for technological systems. On the ground, extreme geomagnetic behavior has an impact on navigation and position accuracy and the operation of power grids and pipeline networks. We therefore use a number of decades of one-minute mean magnetic data from magnetic observatories in Europe, together with the technique of extreme value statistics, to provide a preliminary exploration of the extremes in magnetic field variations and their one-minute rates of change. These extremes are expressed in terms of the variations that might be observed every 100 and 200 years in the horizontal strength and in the declination of the field. We find that both measured and extrapolated extreme values generally increase with geomagnetic latitude (as might be expected), though there is a marked maximum in estimated extreme levels between about 53 and 62 degrees north. At typical midlatitude European observatories (55–60 degrees geomagnetic latitude), compass variations may reach approximately 3–8 degrees/minute, and horizontal field changes may reach 1000–4000 nT/minute, in one magnetic storm once every 100 years. For storm return periods of 200 years the equivalent figures are 4–11 degrees/minute and 1000–6000 nT/minute

¹⁵N-amino sugar stable isotope probing (¹⁵N-SIP) to trace the assimilation of fertiliser-N by soil bacterial and fungal communities

Although amino sugars represent a major component of soil organic nitrogen (ON), the assimilation of nitrate (NO3−) and ammonium (NH4+) into amino sugars (AS) by soil bacteria and fungi represents a neglected aspect of the global N cycle. A deeper knowledge of AS responses to N fertiliser addition may help enhance N use efficiency (NUE) within agricultural systems. Our aim was to extend a sensitive compound-specific 15N-stable isotope probing (SIP) approach developed for amino acids (AAs) to investigate the immobilization of inorganic N into a range of amino sugars (muramic acid, glucosamine, galactosamine, mannosamine). Laboratory incubations using 15N-ammonium and 15N-nitrate applied at agriculturally relevant rates (190 and 100 kg N ha−1 for 15NH4+ and 15NO3−, respectively) were carried out to obtain quantitative measures of N-assimilation into the AS pool of a grassland soil over a 32-d period. Using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) we found that δ15N values for individual AS reflected differences in routing of the applied ammonium and nitrate. The contrasting N-assimilation dynamics of bacterial and fungal communities were demonstrated through determinations of percentage 15N incorporation into diagnostic AS. N-assimilation dynamics of the bacterial community were altered with the applied substrate whilst fungal N-assimilation dynamics were unaffected. Rates and fluxes of the applied N-substrates into the bacterial AS pool reflected known biosynthetic pathways for AS, with fungal glucosamine appearing to be biosynthetically further from the applied substrates than bacterial glucosamine due to different turnover rates. This sensitive and specific compound specific 15N-SIP approach using AS, building on existing approaches with AAs, enables differentiation of N assimilation dynamics within the microbial community and assessment of microbial NUE with agriculturally relevant fertilisation rates

The invasive kudzu bug, Megacopta cribraria (Hemiptera: Plataspidae) as an agricultural and nuisance pest

The invasive “kudzu bug,” Megacopta cribraria (Hemiptera: Plataspidae) is a native of Asia that was found in northeastern Georgia in fall 2009. This insect has since spread rapidly throughout the southeastern U.S., and is abundant in much of South Carolina. Megacopta cribraria feed on the vascular fluid of several legumes, primarily kudzu, Puereria montana var. lobata, and soybeans, Glycine max. These insects enter soybean fields in often alarming numbers, leaving conspicuous lesions on soybean stems and potentially reducing yields. In addition, M. cribraria congregate on homes and other structures in late fall as they seek overwintering sites, potentially becoming a nuisance pest where populations are large. We examined M. cribraria as a yield reducing pest of soybeans and as a nuisance pest of buildings. Large populations of M. cribraria in caged soybean plots resulted in yield losses of up to 59.6%, and yield reductions were similar in both 2011 and 2012. Several professional-use insecticides were effective in controlling M. cribraria on a variety of building material surfaces, and in some insecticide × surface combinations activity was maintained 30 days post-application. These results contribute to our still developing understanding of this insect as an agricultural and nuisance pest

Development of Alditol Acetate Derivatives for the Determination of 15N-Enriched Amino Sugars by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry

Amino sugars can be used as indices to evaluate the role of soil microorganisms in active nitrogen (N) cycling in soil. This paper details the assessment of the suitability of gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS) for the analysis of ¹⁵N-enriched amino sugars as alditol acetate derivatives prior to application of a novel ¹⁵N stable isotope probing (SIP) approach to amino sugars. The efficient derivatization and cleanup of alditol acetate derivatives for GC was achieved using commercially available amino sugars, including glucosamine, mannosamine, galactosamine, and muramic acid, as laboratory standards. A VF-23ms stationary phase was found to produce optimal separations of all four compounds. The structure of the alditol acetate derivatives was confirmed using gas chromatography/mass spectrometry (GC/MS). For GC–C–IRMS determinations, implementation of a two-point normalization confirmed the optimal carrier gas flow rate to be 1.7 mL min^–1. Linearity of δ¹⁵N value determinations up to δ¹⁵N_t of 469 ± 3.1‰ (where δ¹⁵N_t is the independently measured δ¹⁵N value) was confirmed when 30 nmol N was injected on-column, with the direction of deviation from δ¹⁵N_t at low sample amount dependent on the ¹⁵N abundance of the analyte. Observed between- and within-run memory effects were significant (<i>P</i> < 0.007) when a highly enriched standard (469 ± 3.1‰) was run; therefore, analytical run order and variation in ¹⁵N enrichment of analytes within the same sample must be considered. The investigated parameters have confirmed the isotopic robustness of alditol acetate derivatives of amino sugars for the GC–C–IRMS analysis of ¹⁵N-enriched amino sugars in terms of linearity over an enrichment range (natural abundance to 469 ± 3.1‰) with on-column analyte amount over 30 nmol N

Scientists and public: is the information flow direction starting to change?

Over half of the population of the UK own a smartphone, and about the same number of people uses social media such as Twitter. For the British Geological Survey (BGS) this means millions of potential reporters of real-time events and in-the-field data capturers, creating a new source of scientific information that could help to better understand and predict natural processes

Higher education, mature students and employment goals: policies and practices in the UK

This article considers recent policies of Higher Education in the UK, which are aimed at widening participation and meeting the needs of employers. The focus is on the growing population of part-time students, and the implications of policies for this group. The article takes a critical perspective on government policies, using data from a major study of mature part-time students, conducted in two specialist institutions in the UK, a London University college and a distance learning university. Findings from this study throw doubt on the feasibility of determining a priori what kind of study pathway is most conducive for the individual in terms of employment gains and opportunities for upward social mobility. In conclusion, doubts are raised as to whether policies such as those of the present UK government are likely to achieve its aims. Such policies are not unique to the UK, and lessons from this country are relevant to most of the developed world