Avian Use of Harvested Crop Fields in North Dakota During Spring Migration

Broad-spectrum herbicide applications and improved harvesting efficiency of crops have reduced the availability of weed seeds and waste grains for game and nongame wildlife. Over the last decade, corn and soybean plantings have steadily increased in the Prairie Pothole Region (PPR) of North Dakota, while sunflower plantings have declined. The PPR is an important corridor for migratory birds, and changes in food availabilities at stopover habitats may affect how food resources are used. In early spring 2003 and 2004, we compared bird use of harvested fields of sunflower, soybeans, small grains, and corn in the PPR of North Dakota. Across both years and all crop types, we observed 20,400 birds comprising 29 species. Flocks of Lapland Longspurs (Calcarius lapponicus) and Horned Larks (Eremophila alpestris) and flocks of Red-winged Blackbirds (Agelaius phoeniceus) made up 60% and 15%, respectively, of the bird counts. We found that species richness and bird densities were higher in harvested sunflower fields and cornfields than in harvested small-grain and soybean fields, with soybean fields harboring the fewest species and lowest bird density. Blackbird densities tended to be lower in fields tilled after fall harvest than in fields not tilled. These results suggest that some granivorous bird populations in the Northern Great Plains could be positively affected by planting of row crops with postharvest vertical structure (e.g., sunflower, corn) and use of no-till land management practices.

Crop, Native Vegetation, and Biofuels: Response of White- Tailed Deer to Changing Management Priorities

The expansion of the cellulosic biofuels industry throughout the United States has broad-scale implications for wildlife management on public and private lands. Knowledge is limited on the effects of reverting agriculture to native grass, and vice versa, on size of home range and habitat use of white-tailed deer (Odocoileus virginianus). We followed 68 radio-collared female deer from 1991 through 2004 that were residents of DeSoto National Wildlife Refuge (DNWR) in eastern Nebraska, USA. The refuge was undergoing conversion of vegetation out of row-crop agriculture and into native grass, forest, and emergent aquatic vegetation. Habitat in DNWR consisted of 30% crop in 1991 but removing crops to establish native grass and wetland habitat at DNWR resulted in a 44% reduction in crops by 2004. A decrease in the amount of crops on DNWR contributed to a decline in mean size of annual home range from 400 ha in 1991 to 200 ha in 2005 but percentage of crops in home ranges increased from 21% to 29%. Mean overlap for individuals was 77% between consecutive annual home ranges across 8 years, regardless of crop availability. Conversion of crop to native habitat will not likely result in home range abandonment but may impact disease transmission by increasing rates of contact between deer social groups that occupy adjacent areas. Future research on condition indices or changes in population parameters (e.g., recruitment) could be incorporated into the study design to assess impacts of habitat conversion for biofuel production.

RP94-217 No. 18 Use of Crop Futures and Options by the Nontrader

Crop producers make a number of decisions that are market related. They may be categorized as financial decisions, production decisions, or marketing decisions. All three decisions depend on what prices are likely to be at some specific time in the future. The marketing decisions is complex. This research publication discusses the number of alternatives that are available even for the producer who does not directly buy or sell futures or options contracts.

New 2010 Crop Enterprise Budgets

The 2010 Crop Enterprise Budgets will soon be published. They will be available on the web in two places: the University of Nebraska’s “Crop Watch” website (http://cropwatch.unl.edu) in the Economics and Marketing section, and on the Agricultural Economics website at http://www.agecon.unl.edu.

REDUCTION IN RODENT POPULATIONS THROUGH INTERMITTENT CONTROL OPERATIONS IN THE CROPPING ECOSYSTEM OF THE INDIAN DESERT

Control operations at 6-month intervals, continued for four years in crop fields, reduced the rodent population to 5.08 percent losses to agricultural production. After eight crop seasons, a significant reduction in rodent density was observed in treated areas when compared with that of the control areas (P < 0.01). Correlation between pre-treatment population index (y) and number of seasons (log of x) was found to be 0.91 (P < 0.01). A relationship was established between y and x : y = 0.804.0-0.9621 log x. From this equation, it can be inferred that rodent population will reach zero level after treating crop fields continuously for6.85 or say 7.0 (seven) seasons. After control, the numbers of predominant rodents, Tatera indica, Meriones hurrianae and Rattus meltada. were significantly reduced and the residual population was composed of Mus booduga. Gerbillus spp., Rattus gleadowi. Golunda ellioti and Funambulus pennanti.

DEVELOPMENTAL STATUS OF N-(3-CHLORO-4-METHYLPHENYL) ACETAMIDE AS A CANDIDATE BLACKBIRD/STARLING ROOST TOXICANT

Large winter roosts of blackbirds (Icteridae) and starlings (Sturnus vulgaris) often cause conflicts, both real and imagined, between the birds and local human popula- tions. These conflicts may range from objections to the noise and odor engendered by thousands or millions of birds, to fear of epidemic human and livestock diseases, and the possibility of economic losses from crop depredations. Many people believe the most direct way to combat these conflicts is to reduce local roosting populations by kill- ing the birds. In response to this perceived need for a roost toxicant, the U.S. Fish and Wildlife Service (FWS) developed PA-14, a surfactant which can be aerially applied to problem roosts for population reduction (Lefebvre and Seubert 1970). Successful use of this material, however, requires concurrent rainfall and low temperatures, conditions which may not occur sufficiently often to permit roost treatment at desired times or places. Because of this difficulty, and continued pressures from management person- nel and the agricultural community, the Service has continued its search for a safe, ef- fective roost toxicant usable without severe weather restrictions. One of the current candidate materials is N-(3-chloro-4-methylphenyl)acetamide (CAT, DRC-2698), a derivative of StarlicideR (DRC-1339). This compound was initially developed by S.A. Peoples of the University of California-Davis (Peoples et al. 1976). California researchers are still investigating the avicidal potential of CAT, mainly on baits and in wick perches, while FWS interest has centered thus far on its possible utility as an aerially applied roost treatment. This report is a summary of our investigations to date.

SEASONAL, HABITAT AND SEX-SPECIFIC PATTERNS OF FOOD UTILIZATION BY RED-WINGED BLACKBIRDS (Agelaius phoeniceous) IN EASTERN ONTARIO AND THEIR ECONOMIC IMPORTANCE

Crop depredation by red-winged blackbirds (Agelaius phoeniceus) causes serious economic losses to agricultural crops each year in both Canada and the United States. The concentration of vulnerable, monocultural crops, particularly corn, during periods when large flocks of blackbirds congregate in roosting areas prior to migration has invariably led to heavy feeding pressure (Stone et al., 1972; Wiens and Dyer, 1975; Tyler et al., 1978). Efforts to reduce damage levels by mechanical and chemical dispersal agents have been largely unsuccessful, at least in terms of a long-term solution to the problem. Recently, the lethal control of blackbird populations using surfactants has been proposed. However, the potential repercussions of the removal of substantial numbers of birds from northern breeding areas are virtually unknown (Robertson et al., 1978). Much of the research dealing with the feeding ecology of red-winged blackbirds has been limited to fall and winter periods when large aggregations of birds are actively involved in crop depredation (Goddad, 1969; Williams, 1976; Dolbeer et al., 1978) or pose a potential health hazard (Monroe and Cronholm, 1976). However, what is not known is the degree to which the removal of deleterious weed seed and insect pests cited in several studies (Bird and Smith, 1964; Mott et al., 1972; Robertson et al., 1978) might be of potential value to agriculture. The issue of whether the benefits derived from redwing foraging compensate for the negative aspects associated with crop depredation and health hazards remains largely unresolved. The present study attempted to evaluate the pest status of this species using diet information derived from food habits analysis conducted during the residency of red- winged blackbirds in a northern breeding area. By determining how the feeding ecology of red-winged blackbirds varies on a seasonal basis, among different breeding habitats and between sexes, we hoped to determine more realistically which segments of the population might be responsible for the greatest benefits or detriments and, thereby, more accurately evaluate the economic impact of the species as a whole. To achieve this aim, the study provides an accurate description of the common insects and weed pests utilized by redwings. By determining the relative proportions of those items known to be detrimental, we hoped to illustrate, at least qualitatively, the degree to which redwing foraging is comprised of both beneficial and harmful components.

BIRD DEPREDATION ON RICE AND OTHER GRAINS IN ARKANSAS

In Arkansas, blackbirds are responsible for appreciable damage to rice, grain sorghum, oats, wheat, rye, and corn. By far, the greatest damage is to rice. As is shown in the following table, the losses to rice producers amounted to an estimated $3,049,055 in 1968, the last year that a survey was made. Nearly two-thirds (63%) of this loss was to standing rice destroyed and to the cost of bird control measure in standing rice. The remaining losses ($2,140,320 ) are to seeding or to efforts to control bird depredations to new seeding, (see Table 1). Blackbird damage to grain sorghum and corn was mostly to standing grain; that to oats, wheat and rye, to seeding, although there is occasional damage to standing grain. Additional problems are caused by blackbirds in feed lots. The total losses to Arkansas agricultural producers due to blackbirds in 1968 was about $3,500,000. Bird damage in a specific locality and on specific crops seems to vary in intensity from year to year. However, surveys during the past ten years suggest a fairly consistent level of total damage state-wide. The damage in 1968-and I believe in 1969—was somewhat lighter than we have come to expect from past exper¬ience. (See table 2.) On a per acre basis the damage in 1968 showed a considerable decline when compared to previous years. A part of this decline is probably a temporary situation. Some of the decline in losses to rice and grain sorghum, however, are due to changes in varieties, such as development of bird-resistant milo, and to changes in cultural methods. Further appreciable reductions due to changes in these factors seem unlikely, (see table 3.) Since rice producers sustain the greatest losses to birds, they have generated the greatest demand for bird control programs. Three species are responsible for most of the damage to rice. They are the red-winged blackbird, common grackle and brown-headed cowbird. These birds have created problems for rice producers since the first successful rice crop was grown near Lonoke, Arkansas, in 1904.

Morfologia do testículo e espermatogênese em Telchin licus (Drury, 1773) (Lepidoptera: Castiniidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Irreversible color vision losses in patients with chronic mercury vapor intoxication

This longitudinal study addresses the reversibility of color vision losses in subjects who had been occupationally exposed to mercury vapor. Color discrimination was assessed in 20 Hg-exposed patients (mean age = 42.4 +/- 6.5 years; 6 females and 14 males) with exposure to Hg vapor during 10.5 +/- 5.3 years and away from the work place (relative to 2002) for 6.8 +/- 4.2 years. During the Hg exposure or up to one year after ceasing it, mean urinary Hg concentration was 47 +/- 35.4 mu g/g creatinine. There was no information on Hg urinary concentration at the time of the first tests, in 2002 (Ventura et al., 2005), but at the time of the follow-up tests, in 2005, this value was 1.4 +/- 1.4 mu g/g creatinine for patients compared with 0.5 +/- 0.5 mu g/g creatinine for controls (different group from the one in Ventura et al. (2005)). Color vision was monocularly assessed using the Cambridge Colour Test (CCT). Hg-exposed patients had significantly worse color discrimination (p < 0.02) than controls, as evaluated by the size of MacAdam`s color discrimination ellipses and color discrimination thresholds along protan, deutan, and tritan confusion axes. There were no significant differences between the results of the study in Ventura et al. (2005) and in the present follow-up measurements, in 2005, except for worsening of the tritan thresholds in the best eye in 2005. Both chromatic systems, blue-yellow and red-green, were affected in the first evaluation (Ventura et al., 2005) and remained impaired in the follow-up testing, in 2005. These findings indicate that following a long-term occupational exposure to Hg vapor, even several years away from the source of intoxication, color vision impairment remains irreversible.

Visual field losses in workers exposed to mercury vapor

Visual field losses associated with mercury (Hg) exposure have only been assessed in patients exposed to methylmercury. Here we evaluate the automated visual field in 35 ex-workers (30 males; 44.20+/-5.92 years) occupationaly exposed to mercury vapor and 34 controls (21 males; 43.29+/-8.33 years). Visual fields were analyzed with the Humphrey Field Analyzer II (model 750i) using two tests: the standard automated perimetry (SAP, white-on-white) and the short wavelength automated perimetry (SWAP, blue-on-yellow) at 76 locations within a 27 degrees central visual field. Results were analyzed as the mean of the sensitivities measured at the fovea, and at five successive concentric rings, of increasing eccentricity, within the central field. Compared to controls, visual field sensitivities of the experimental group measured using SAP were lower for the fovea as well as for all five eccentricity rings (p<0.05). Sensitivities were significantly lower in the SWAP test (p<0.05) for four of the five extra-foveal eccentricity rings; they were not significant for the fovea (p = 0.584) or for the 15 degrees eccentricity ring (p = 0.965). These results suggest a widespread reduction of sensitivity in both visual field tests. Previous reports in the literature describe moderate to severe concentric constriction of the visual field in subjects with methylmercury intoxication measured manually with the Goldman perimeter. The present results amplify concerns regarding potential medical risks of exposure to environmental mercury sources by demonstrating significant and widespread reductions of visual sensitivity using the more reliable automated perimetry. (C) 2007 Elsevier Inc. All rights reserved.

Chromatic discrimination losses in multiple sclerosis patients with and without optic neuritis using the Cambridge Colour Test

We assessed chromatic discrimination in multiple sclerosis (MS) patients both with (ON) and without (no ON) a history of optic neuritis using the Cambridge color test (CCT). Our goal was to determine the magnitude and chromatic axes of any color vision losses in both patient groups, and to evaluate age-related changes in chromatic discrimination in both patient groups compared to normals. Using the CCT, we measured chromatic discrimination along the protan, deutan and tritan axes in 35 patients with MS (17 ON eyes) and 74 age matched controls. Color thresholds for both patient groups were significantly higher than controls` along the protan and tritan axes (P < 0.001). In addition, the ON and no-ON groups differed significantly along all three-color axes (p < 0.001). MS patients presented a progressive color discrimination impairment with age (along the deutan and tritan axes) that was almost two times faster than controls, even in the absence of ON. These findings suggest that demyelinating diseases reduce sensitivity to color vision in both red-green and blue-yellow axes, implying impairment in both parvocellular and koniocellular visual pathways. The CCT is a useful tool to help characterize vision losses in MS and the relationship between these losses and degree of optic nerve involvement.

Top spoilage losses in maize silage sealed with plastic films with different permeabilities to oxygen

The quality of plastic films used for horizontal silos is important to limit losses in the upper silage layer. The aim of this work was to study the effectiveness of different plastic films in reducing the top losses in maize silage. The following treatments were evaluated: (i) coextruded polyethylene/polyamide oxygen barrier film (OB), (ii) polyethylene film (PE), (iii) polyvinyl chloride film (PVC), and (iv) coextruded PE/polyvinyl alcohol film (PVOH). These treatments differed according to oxygen permeability with values of 75, 722, 982 and 289 cm(3) m(-2) per 24 hour respectively. OB and PVOH films had better temperature and fermentation profiles than the more permeable films. The OB film was effective in reducing the dry-matter (DM) losses during storage (82 g kg(-1)), and the PVOH film had an intermediate value of DM loss (101 g kg(-1)). PE and PVC films had higher losses (138 and 145 g kg(-1) respectively). Oxygen permeability of the films promoted a positive correlation with DM losses (P < 0.05; r2 = 0.945). The results indicate that O2 permeability through the plastic film is a crucial factor for maintaining silage quality in the upper layer of the silo when it is perfectly sealed.

A Novel Stress-Induced Sugarcane Gene Confers Tolerance to Drought, Salt and Oxidative Stress in Transgenic Tobacco Plants

Background: Drought is a major abiotic stress that affects crop productivity worldwide. Sugarcane can withstand periods of water scarcity during the final stage of culm maturation, during which sucrose accumulation occurs. Meanwhile, prolonged periods of drought can cause severe plant losses. Methodology/Principal Findings: In a previous study, we evaluated the transcriptome of drought-stressed plants to better understand sugarcane responses to drought. Among the up-regulated genes was Scdr1 (sugarcane drought-responsive 1). The aim of the research reported here was to characterize this gene. Scdr1 encodes a putative protein containing 248 amino acids with a large number of proline (19%) and cysteine (13%) residues. Phylogenetic analysis showed that ScDR1is in a clade with homologs from other monocotyledonous plants, separate from those of dicotyledonous plants. The expression of Scdr1 in different varieties of sugarcane plants has not shown a clear association with drought tolerance. Conclusions/Significance: The overexpression of Scdr1 in transgenic tobacco plants increased their tolerance to drought, salinity and oxidative stress, as demonstrated by increased photosynthesis, water content, biomass, germination rate, chlorophyll content and reduced accumulation of ROS. Physiological parameters, such as transpiration rate (E), net photosynthesis (A), stomatal conductance (gs) and internal leaf CO2 concentration, were less affected by abiotic stresses in transgenic Scdr1 plants compared with wild-type plants. Overall, our results indicated that Scdr1 conferred tolerance to multiple abiotic stresses, highlighting the potential of this gene for biotechnological applications.

EROSION LOSSES FROM RUNOFF: INTERACTION OF SOIL COVER AND EROSION CONTROL PRACTICE

The flow of sediment from cropped land is the main pollutant of water sources in rural areas. Due to this fact, it is necessary to develop and implement technologies that will reduce water and sediment discharges. Accordingly, an experiment was conducted in the Department of Biosystems Engineering - ESALQ / USP, Piracicaba - SP with the objective to evaluate the effect of different soil cover (bean, grass and bare ground) and erosion control practices (wide base terraces and infiltration furrows in slopes (no practices to control erosion)) while measuring water losses in runoff. The statistical design adopted was randomized blocks in a 3x3 factorial scheme resulting in 9 treatments with 3 replicates (blocks). The period of rainfall data collection was December 6, 2007 to April 11, 2008. A 21.1 cm diameter rain gauge was installed in the experimental area. Terraces were the most efficient practices for reducing erosion losses in the treatments with infiltration furrows being better than the control treatment. Bean was more effective than grass in reducing erosion. Bare ground was the least efficient.