Infestation Rates and Tiller Morphology Effects by the Switchgrass Moth on Six Cultivars of Switchgrass

Switchgrass (Panicum virgatum L.) is a potential biomass crop for native species-based biofuel systems in North America. A recently identified pest of switchgrass, the switchgrass moth, Blastobasis repartella (Dietz) (Lepidoptera: Coleophoridae), feeds in the basal above-ground internodes and below-ground in the proaxis and rhizomes, causing premature tiller and rhizome loss. Our goal was to determine genetic and temporal variation among six upland cultivars for frequency of tiller infestation by larvae of the switchgrass moth in mature stands in the northern Great Plains and if variation in biomass production was associated with variation in frequency of infestation. Data were collected in 2011 and 2012 for tiller density, biomass, frequency of infestation, number of leaves per healthy and infested tiller, and weights of healthy and infested tillers. Differences were found among cultivars for tiller density, biomass yield, and numbers of leaves per healthy and infested tillers. ‘Summer’, ‘Sunburst’, ‘Pathfinder’, and ‘Cave-In-Rock’ were the highest yielding cultivars. Mean frequency of infestation was different between 2011 (6.7 %) and 2012 (9.6 %). Infested tillers had one less collared leaf than healthy tillers. The weights of healthy tillers were ca. 3× those of infested tillers in both years, suggesting an impact on biomass accumulation and economic value. Levels of infestation were similar for all six cultivars, indicating no feeding preference by the switchgrass moth larva among genetically diverse cultivars of switchgrass. Regression of biomass yield on frequency of infestation showed negative linear relationships for ‘Carthage’ and ‘Kentucky 1625’.     

A New Species of Gall Midge (Diptera: Cecidomyiidae) Infesting Switchgrass in the Northern Great Plains

A new species of gall midge, Chilophaga virgati Gagn?? (Diptera: Cecidomyiidae), collected from tillers of switchgrass at Brookings, South Dakota (44.31134?? N, 96.78374?? W) is described here. Plant morphological symptoms of infestation and frequency of tillers infested are also provided. Full-grown larvae of C. virgati were found inside the sheath of the flag leaf of reproductive tillers of clonally replicated spaced plants of a selected southern upland population of switchgrass during October 2008 and 2009. Infested tillers were shorter and lighter than normal tillers and had panicles that were partially encased in the sheath of the flag leaf due to reduced elongation of the peduncle as a result of the feeding of larvae of C. virgati at the proximal end of the panicle and in the intercalary meristem area of the peduncle. Variation was found among 10 genotypes for percentage of tillers infested by C. virgati, with a range from 7.2% to 21.8%. No difference was found between years for infestation rate (12.7% in 2008 and 14.3% in 2009). The mass of infested tillers was 35% that of normal tillers, and infested tillers produced no appreciable amount of viable seeds. Results of this research revealed that C. virgati had direct negative impacts on biomass and seed production in spaced plant nurseries of switchgrass. C. virgati was also observed in seeded swards of northern upland switchgrass cultivars, but its impact in seeded swards has not yet been determined.     

Morphology and biomass production of prairie cordgrass on marginal lands

Prairie cordgrass (Spartina pectinata Link.) is indigenous throughout most of the continental United States and Canada to 60°N latitude and is well suited to marginal land too wet for maize (Zea mays L.) and switchgrass (Panicum virgatum L.). Evaluations of prairie cordgrass in Europe and North America indicated it has high potential for biomass production, relative to switchgrass, in short‐season areas. Our objective was to describe morphology and biomass production and partitioning in mature stands of ‘Red River’ prairie cordgrass and determine biomass production of natural populations on marginal land. This study was conducted from 2000 to 2008 in eastern South Dakota. Mean biomass production of mature stands of Red River was 12.7 Mg ha^?1. Leaves composed >88% of the biomass, and 60% of the tillers had no internodes. Belowground biomass to a depth of approximately 25 cm, not including roots, was 21 Mg ha^?1. Tiller density ranged from 683 tillers m^?2 for a 10‐year‐old stand to 1140 tillers m^?2 for a 4‐year‐old stand. The proaxis was composed of about eight phytomers, with rhizomes originating at proximal nodes and erect tillers at distal nodes. Vegetative propagation was achieved by both phalanx and guerilla growth. Differences among natural populations for biomass were expressed on gravelly marginal land. However, production, averaged across populations, was low (1.37 Mg ha^?1) and comparable to ‘Cave‐In‐Rock’ switchgrass (1.67 Mg ha^?1) over a 4‐year period. The large carbon storage capacity of prairie cordgrass in proaxes and rhizomes makes it useful for carbon sequestration purposes. Prairie cordgrass should be compared with switchgrass and other C₄ perennial grasses along environmental gradients to determine optimum landscape positions for each and to maximize bioenergy production and minimize inputs.     

Switchgrass Biomass and Nitrogen Yield with Over-Seeded Cool-season Forages in the Southern Great Plains

In dry climates with long, hot summers and freezing winters, such as that of the southern Great Plains of North America, switchgrass (Panicum virgatum L.) has proven potential as a cellulosic bioenergy feedstock. This trial looked at dry matter (DM) and N yield dynamics of switchgrass overseeded with cool-season legumes and rye (Secale cereale L.), compared to switchgrass fertilized with 0, 56 and 112 kg N ha^-1 yr^-1 at an infertile and a fertile location. Optimal N fertilizer rate on switchgrass was 56 kg N ha^-1 at the infertile location. Legume yield was greater in the first season after planting, compared to subsequent years where annual legumes were allowed to reseed and alfalfa (Medicago sativa L.) was allowed to grow. This suggests that the reseeding model for annual legumes will not work in switchgrass swards grown for biomass unless soil seed banks are built up for more than one year, and that overseeding with alfalfa may have to be repeated in subsequent years to build up plant populations. Overseeding rye and legumes generally did not suppress or enhance switchgrass biomass production compared to unfertilized switchgrass. However, cumulative spring and fall biomass yields were generally greater due to winter and spring legume production, which could be beneficial for grazing or soil conservation systems, but not necessarily for once-yearly late autumn harvest biofuel production systems.     

Impact of Harvest Time and Cultivar on Conversion of Switchgrass to Bio-oils Via Fast Pyrolysis

The study of the effects of harvest time on switchgrass (Panicum virgatum L.) biomass and bioenergy production reported herein encompasses a large study evaluating the harvest of six switchgrass cultivars grown at three northern US locations over 3 years, harvested at upland peak crop (anthesis), post-frost, and post-winter. Delaying harvest of switchgrass until after frost and until after winter has resulted in decreased yields of switchgrass and reduced amounts of minerals in the biomass. This report examines how changes in biomass composition as a result of varying harvest time and other factors affect the distribution of products formed via fast pyrolysis. A subset (50) of the population (n = 864) was analyzed for fast pyrolysis and catalytic pyrolysis (zeolite catalyst) product yields using a pyrolysis-GC/MS system. The subset was used to build calibrations that were successful in predicting the pyrolysis product yield using near-infrared reflectance spectroscopy (NIRS), and partial least squares predictive models were applied to the entire sample set. The pyrolysis product yield was significantly affected by the field trial location, year of harvest, cultivar, and harvest time. Delaying harvest time of the switchgrass crop led to greater production of deoxygenated aromatics improving the efficiency of the catalytic fast pyrolysis and bio-oil quality. The changes in the pyrolysis product yield were related to biomass compositional changes, and key relationships between cell wall polymers, potassium concentration in the biomass, and pyrolysis products were identified. The findings show that the loss of minerals in the biomass as harvest time is delayed combined with the greater proportion in cellulose and lignin in the biomass has significant positive influences on conversion through fast pyrolysis.     

The Mycorrhizal Fungus, Sebacina vermifera, Enhances Seed Germination and Biomass Production in Switchgrass (Panicum virgatum L)

Seed dormancy and slow seedling establishment are two major concerns in switchgrass (Panicum virgatum L.) production, often resulting in a poor stand with reduced productivity. Studies were conducted to investigate the stability of artificial associations between switchgrass and the ectomycorrhizal fungus, Sebacina vermifera, and to evaluate the potential benefits of this novel association in seed germination and biomass production. All six strains of S. vermifera tested had a high frequency of colonization on switchgrass roots of a synthetic cultivar NF/GA-993. The positive effects of the associations were reflected in plant height, root length, and biomass production. Inoculated plants produced as much as 75%, 113%, and 18% more shoot biomass than un-inoculated control plants in the first, second, and third harvest, respectively, with no consequent reduction in root biomass. Further, culture filtrates from some strains of S. vermifera increased seed germination in the switchgrass cultivar Kanlow by 52% over the control (p?<?0.05). This study illustrates the great potential of microbial associations to increase biomass production and productivity of switchgrass.     

The Switchgrass Gall Midge (Chilophaga virgati Gagné) in the Northern Great Plains

Switchgrass (Panicum virgatum L.) is considered to be a highly promising bioenergy crop. However, little is known about insect pests that impact its utilization for this purpose. The switchgrass gall midge [Chilophaga virgati Gagné (Diptera: Cecidomyiidae)], which was first discovered in 2008 at Brookings, SD, USA, is shown to have a negative impact on biomass and seed yields of switchgrass. Our objectives were to increase knowledge of the biology of the midge by describing its life stages and any parasitoids that have biological control potential. Data collections were made during May to December in 2011 and April to late autumn in 2012. The gall midge adult is active from early June to late July. This insect overwinters as a late instar larva, usually in large aggregations, enclosed in the sheath of the flag leaf of dry tillers. The mean number of larvae was 31, with a range of 6 to 85 per tiller. Infested tillers m^?2 varied among three phenologically distinct cultivars. The late flowering cultivar ‘Cave-In-Rock’ was more heavily infested (>2×) than the early flowering ‘Dacotah’. A newly discovered parasitoid, Platygaster chilophagae Buhl (Hymenoptera: Platygastridae) and a species of Quadrastichus sp. (Hymenoptera: Eulophidae) were reared from gall midge larvae. These results will be valuable to entomologists, switchgrass breeders, and agronomists as a guide to the occurrence and activities of the gall midge.     

Geographic distribution and host plants of Raoiella indica and associated mite species in northern Venezuela

The red palm mite (RPM), Raoiella indica Hirst (Acari: Tenuipalpidae), is an invasive pest in the New World, where it is currently considered a serious threat to coconut and banana crops. It was first reported from northern Venezuela in 2007. To determine its current distribution in this country, surveys were carried out from October 2008 to April 2010 on coconut (Cocos nucifera L.), banana (Musa spp.), ornamental plants and weeds in northern Venezuela. Higher population levels of RPM were registered on commercial coconut farms in Falcón and Sucre states but also on other plant species naturally growing along the coastal line in Anzoategui, Aragua, Carabobo, Monagas and Nueva Esparta states. Out of 34 botanical species evaluated, all RPM stages were observed only on eight arecaceous, one musaceous and one streliziaceous species, indicating that the pest developed and reproduced only on these plants. Mite specimens found on weeds were considered spurious events, as immature stages of the pest were never found on these. Amblyseius largoensis (Muma) (Acari: Phytoseiidae) was the most frequent predatory mite associated with RPM in all sampling sites. The results indicate that RPM has spread to extensive areas of northern Venezuela since its initial detection in Güiria, Sucre state. Considering the report of this pest mite in northern Brazil in the late 2009, additional samplings in southern Venezuela should be carried out, to evaluate the possible presence of RPM also in that region.     

Impact of the fungus Balansia henningsiana on Panicum agrostoides: frequency of infection,plant growth and reproduction,and resistance to pests

Summary The impact of the systemic fungus Balansia henningsiana (Clavicipitaceae) on the grass Panicum agrostoides was examined in field and greenhouse studies comparing infected and uninfected plants. Approximately one-half of all plants in three populations located in southern Indiana were infected. In field samples and greenhouse studies infected plants were significantly heavier than uninfected plants and produced significantly more tillers. Infection tended to suppress flowering but occasional asymptomatic tillers on infected plants produced healthy inflorescences. Although infected plants produced fewer inflorescences than uninfected plants as a proportion of total tillers, absolute numbers of inflorescences were similar in the two groups. Because other grasses infected by different species of Balansia and related fungi often are more resistant to insect damage, pest damage was quantified in one population. No differences between infected and uninfected plants were detected in levels of herbivory but infected plants had significantly less damage by the common leaf spot fungus Alternaria triticina. The results suggest that there is no selective disadvantage for plants infected by B. henningsiana.     

Herbivory and climatic warming: a Mediterranean outbreaking caterpillar attacks a relict, boreal pine species

Climate change can harm many species by disrupting existing interactions or by favouring new ones. This study analyses the foreseeable consequences of climatic warming in the distribution and dynamics of a Mediterranean pest that causes severe defoliation, the pine processionary caterpillar Thaumetopoea pityocampa, and the effects upon the relict Andalusian Scots pine Pinus sylvestris nevadensis in the Sierra Nevada mountains (southeastern Spain). We correlated a set of regional data of infestation by T. pityocampa upon Scots pine, from a broad ecological gradient, with climatic data for the period 1991–2001, characterized by alternating warm and cold winters. Defoliation intensity shows a significant association with previous warm winters, implying that climatic warming will intensify the interaction between the pest and the Scots pine. The homogeneous structure of the afforested pine woodlands favours the outbreak capacity of the newcomer, promoting this new interaction between a Mediterranean caterpillar pest and a boreal tree at its southern distribution limit.     

Competitive effects of cultivar and wild switchgrass on other native grasses

There is mounting concern that selection and breeding of native grasses for greater biomass production could promote weediness. Yet little is known about the invasion potential or ecological impacts of such selectively bred native grasses. Here we focus on cultivars of native switchgrass (Panicum virgatum L.) that have undergone selection, breeding, and intraspecific hybridization to improve agronomic traits for biomass production. We evaluated the competitive effects of switchgrass cultivars (EG-2101 and ‘Trailblazer’) and wild switchgrass populations on two native prairie grasses [sideoats grama, Bouteloua curtipendula (Michx.) Torr., and Canada wild rye, Elymus canadensis L.] across a gradient of switchgrass density in a greenhouse. Cultivars produced 48–128% more biomass and reduced sideoats grama biomass by 25–59% more than wild switchgrass. Effects of switchgrass cultivars on Canada wild rye were minimal compared to sideoats grama. Later flowering and larger seed size of cultivars may be contributing to their greater biomass and competitive effects on sideoats grama. These data suggest that breeding switchgrass for enhanced biomass yield may increase competitive effects on some native grasses. Further studies are merited to test the potential for switchgrass biomass cultivars to spread and impact species diversity of restored and remnant native plant communities.     

Switchgrass, Big Bluestem, and Indiangrass Monocultures and Their Two- and Three-Way Mixtures for Bioenergy in the Northern Great Plains

High yielding, native warm-season grasses could be used as renewable bioenergy feedstocks. The objectives of this study were to determine the effect of warm season grass monocultures and mixtures on yield and chemical characteristics of harvested biomass and to evaluate the effect of initial seeding mixture on botanical composition over time. Switchgrass (Panicum virgatum L.), indiangrass [Sorghastrum nutans (L.) Nash], and big bluestem (Andropogon gerardii Vitman) were planted as monocultures and in all possible two- and three-way mixtures at three USA locations (Brookings and Pierre, SD and Morris, MN) during May 2002. Biomass at each location was harvested after a killing frost once annually from 2003 to 2005. Total biomass yield significantly increased with year at all locations. Switchgrass monocultures or mixtures containing switchgrass generally out-yielded big bluestem or indiangrass in monocultures or the binary mixture. Cellulose and hemicellulose concentrations were higher in 2004 and 2005 compared with 2003. Switchgrass or mixtures containing switchgrass tended to have less cellulose than either big bluestem or indiangrass. Results were more variable for total N, lignin, and ash. Switchgrass was the dominant component of all mixtures in which it was present while big bluestem was dominant when mixed with indiangrass. Indiangrass was maintained only in monocultures and declined over years when grown in mixtures at all locations. Our results indicated if biomass yield in the northern Great Plains is a primary objective, switchgrass should be a component of binary or tertiary mixtures that also contain big bluestem and/or indiangrass.     

Forecasting the potential distribution of Spodoptera exigua and S. littoralis (Lepidoptera,Noctuidae) in Iran

The beet armyworm, Spodoptera exigua (Hübner, 1808) and the Egyptian cotton leafworm, S. littoralis (Boisduval, 1833), are amongst the most notorious agricultural pest species in Iran. Spodoptera exigua is considered a serious pest of different crops, whereas S. littoralis is known as an important pest of cotton.In this paper, the potential distribution areas of these species in Iran and the important climatic factors affecting their distribution were predicted using the MaxEnt model and the ArcGIS. The results indicate that the main environmental variables contributing to S. exigua’s distribution were precipitation of the coldest quarter (bio19), average wind speed in April (wind4), and annual precipitation (bio12). Also, minimum temperature of the coldest month (bio6), mean temperature of coldest quarter (bio11), altitude and average wind speed in May (wind5) were dominant climatic factors that affected the potential distribution of S. littoralis. These species overlapped in most parts of coastal areas in the southern and northern parts of Iran, with an average overlapping range of 33.2%. Considering their preferred host plants in Iran, it is necessary to strengthen biosurveillance programes and management of these two species in their suitable areas to prevent further invasion, which endangers agricultural security.     

Developmental Control of Lignification in Stems of Lowland Switchgrass Variety Alamo and the Effects on Saccharification Efficiency

The switchgrass variety Alamo has been chosen for genome sequencing, genetic breeding, and genetic engineering by the US Department of Energy Joint Genome Institute (JGI) and the US Department of Energy BioEnergy Science Center. Lignin has been considered as a major obstacle for cellulosic biofuel production from switchgrass biomass. The purpose of this study was to provide baseline information on cell wall development in different parts of developing internodes of tillers of switchgrass cultivar Alamo and evaluate the effect of cell wall properties on biomass saccharification. Cell wall structure, soluble and wall-bound phenolics, and lignin content were analyzed from the top, middle, and bottom parts of internodes at different developmental stages using ultraviolet autofluorescence microscopy, histological staining methods, and high-performance liquid chromatography (HPLC). The examination of different parts of the developing internodes revealed differences in the stem structure during development, in the levels of free and well-bound phenolic compounds and lignin content, and in lignin pathway-related gene expression, indicating that the monolignol biosynthetic pathway in switchgrass is under complex spatial and temporal control. Our data clearly show that there was a strong negative correlation between overall lignin content and biomass saccharification efficiency. The ester-linked p-CA/FA ratio showed a positive correlation with lignin content and a negative correlation with sugar release. Our data provide baseline information to facilitate genetic modification of switchgrass recalcitrance traits for biofuel production.     

Adult activity and oviposition of corn rootworms,Diabrotica spp. (Coleoptera: Chrysomelidae), in Miscanthus,corn and switchgrass

The ability of the biomass crop Miscanthus (Miscanthus × giganteus Greef and Deuter ex Hodkinson and Renvoize) to support larval development for both United States and European populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, suggests an avenue for interactions with corn (Zea mays L.). To provide context to survival of D. v. virgifera on Miscanthus, adult activity and oviposition of Diabrotica spp. were monitored in central Illinois in 2010–2011 in Miscanthus, corn and switchgrass (Panicum virgatum L.). For D. v. virgifera, vial traps within corn plots captured 3–10 times as many adults as in Miscanthus or switchgrass, while soil samples showed females laid approximately 10 times as many eggs in corn as in the perennial grasses. Adult southern corn rootworms, Diabrotica undecimpunctata howardi Barber, were the most abundant species in 2010 and clearly preferred switchgrass as an adult habitat, with vial traps in switchgrass capturing 5–10 times as many D. u. howardi as those in corn or Miscanthus. Based on the small production areas for Miscanthus and switchgrass (and low use of both by D. v. virgifera), it seems likely that there are no current impacts of these perennial grasses on pest status of Diabrotica spp. in corn or other crops. However, adaptations by Diabrotica spp. to pest management practices suggest they could be a source for interactions between biomass and food or feed crops. Early‐season soil samples did not recover eggs of D. u. howardi, but their use of switchgrass as an adult habitat suggests additional research in areas where switchgrass may be grown near peanuts, alfalfa or other hosts may be needed. Also, investigation of other candidate bioenergy crops known to support Diabrotica spp. larval development is needed to better understand the possible effects of a changing agricultural landscape on corn rootworms.     

Water Use Efficiency by Switchgrass Compared to a Native Grass or a Native Grass Alfalfa Mixture

Perennial grass systems are being evaluated as a bioenergy feedstock in the northern Great Plains. Inter-annual and inter-seasonal precipitation variation in this region will require efficient water use to maintain sufficient yield production to support a mature bioenergy industry. Objectives were to evaluate the impact of a May–June (early season) and a July–August (late season) drought on the water use efficiency (WUE), amount of water used, and biomass production in monocultures of switchgrass (Panicum virgatum L.), western wheatgrass (Pascopyrum smithii (Rydb.) Á. Löve), and a western wheatgrass–alfalfa (Medicago sativa L.) mixture using an automated rainout shelter. WUE was strongly driven by biomass accumulation and ranged from 5.6 to 7.4 g biomass mm^?1 water for switchgrass to 1.06 to 2.07 g biomass mm^?1 water used with western wheatgrass. Timing of water stress affected WUE more in western wheatgrass and the western wheatgrass–alfalfa mixture than switchgrass. Water deficit for the western wheatgrass–alfalfa mixture was 23 % lower than western wheatgrass (P?=?0.0045) and 31 % lower than switchgrass (P?<?0.0001) under the May–June stress water treatment, while switchgrass had a 37 and 38 % greater water deficit than did western wheatgrass or western wheatgrass–alfalfa mixture, respectively (P?<?0.001) under the July–August water stress treatment. Water depletion was always greatest in the upper 30 cm. Switchgrass had greater WUE but resulted in greater soil water depletion at the end of the growing season compared to western wheatgrass and a western wheatgrass–alfalfa mixture which may be a concern under multi-year drought conditions.     

Bioenergy Traits of Ten Switchgrass Populations Grown in the Northeastern/Mid-Atlantic USA

Although switchgrass (Panicum virgatum L.) has emerged as a bioenergy crop throughout the midwestern and southern USA, little evaluation has been conducted on the performance of switchgrass as a bioenergy crop in the Northeast/Mid-Atlantic. The objectives of this study were to evaluate biomass characteristics of ten switchgrass populations grown in New Jersey and to determine which populations are best for use in biomass production. Ten populations of switchgrass were planted in a spaced-plant nursery in Freehold, NJ and evaluated for: winter injury, anthracnose disease caused by Colletotrichum navitas, lodging, tiller density, height, heading and anthesis date, and biomass yield as well as cellulose, hemicellulose, lignin, ash, chlorine, calcium, magnesium, phosphorous, and potassium in 2007 and 2008. Eastern upland populations 9064202 (Cape May Plant Materials Center accession #9064202), High Tide, and Carthage showed the least amount of winter injury, while southern lowland populations Alamo and Cimarron showed the most winter injury. Lowland populations were less susceptible to anthracnose than upland ecotypes and were taller and later maturing with higher cellulose contents. Lowland populations NSL, Cimarron, and Timber showed the least amount of lodging, and upland populations had the highest tiller densities. Lowland populations Cimarron and Timber had the highest biomass yields of 906.9 and 803.6 kg dry matter plant^?1, respectively. Lignocellulosic and mineral contents did not differ greatly among cultivars and generally did not show trends with respect to cytotype. Timber, an eastern lowland ecotype, exhibited the best combination of characteristics and is a promising population for biomass production in the Northeast/Mid-Atlantic region of the USA.     

The distribution of Athetis lepigone and prediction of its potential distribution based on GARP and MaxEnt

Athetis lepigone (Möschler) is a new agronomic pest which has caused serious damages to summer maize in China. In order to effectively monitor it, it is necessary to carry‐out a worldwide investigation on its potential geographical distribution. In this study, we give two ecological niche models, Genetic Algorithm for Rule‐set Production and Maximum Entropy (MaxEnt), to predict the potential geographical distribution of A. lepigone. The results indicate that the suitable areas for A. lepigone are mainly in China (Beijing, Tianjin, central and southern Hebei, northern Jiangsu, Shandong, most of Henan, northern Anhui, central and southern Shanxi, central and southern Shaanxi, small parts of north‐west in Hubei, eastern Gansu, parts of Ningxia, western of Xinjiang and Dandong, and Liaoning) and other Asian countries (South Korea, North Korea and Japan). Parts of Europe (south‐western Russia, Ukraine, Moldova, Romania, Hungary, Bulgaria, Slovenia, and Croatia, Bosnia and Herzegovina, Serbia, parts of Austria, western Poland, the Czech Republic, Germany, northern Italy, Denmark, western Lithuania, Latvia, Estonia, southern Finland and Sweden) are also highly suitable for A. lepigone. In addition, in the states of the USA including Michigan, New York, Chicago, Missouri, Ohio, Illinois and Indiana are also favourable for its occurrence although till now no reports about of this species has been recorded. A jackknife test in MaxEnt showed that the mean temperature of the driest quarter was the most important environmental variable affecting the distribution of this pest.     

Diversity of Nitrogen-Fixing Bacteria Associated with Switchgrass in the Native Tallgrass Prairie of Northern Oklahoma

Switchgrass (Panicum virgatum L.) is a perennial C₄ grass native to North America that is being developed as a feedstock for cellulosic ethanol production. Industrial nitrogen fertilizers enhance switchgrass biomass production but add to production and environmental costs. A potential sustainable alternative source of nitrogen is biological nitrogen fixation. As a step in this direction, we studied the diversity of nitrogen-fixing bacteria (NFB) associated with native switchgrass plants from the tallgrass prairie of northern Oklahoma (United States), using a culture-independent approach. DNA sequences from the nitrogenase structural gene, nifH, revealed over 20 putative diazotrophs from the alpha-, beta-, delta-, and gammaproteobacteria and the firmicutes associated with roots and shoots of switchgrass. Alphaproteobacteria, especially rhizobia, predominated. Sequences derived from nifH RNA indicated expression of this gene in several bacteria of the alpha-, beta-, delta-, and gammaproteobacterial groups associated with roots. Prominent among these were Rhizobium and Methylobacterium species of the alphaproteobacteria, Burkholderia and Azoarcus species of the betaproteobacteria, and Desulfuromonas and Geobacter species of the deltaproteobacteria.