An increasing number of citizen science water monitoring programs is continuously collecting water quality data on streams throughout the United States. Operating under quality assurance protocols, this type of monitoring data can be extremely valuable for scientists and professional agencies, but in some cases has been of limited use due to concerns about the accuracy of data collected by volunteers. Although a growing body of studies attempts to address accuracy concerns by comparing volunteer data to professional data, rarely has this been conducted with large-scale datasets generated by citizen scientists. This study assesses the relative accuracy of volunteer water quality data collected by the Texas Stream Team (TST) citizen science program from 1992-2016 across the State of Texas by comparing it to professional data from corresponding stations during the same time period. Use of existing data meant that sampling times and protocols were not controlled for, thus professional and volunteer comparisons were refined to samples collected at stations within 60 meters of one another and during the same year. Results from the statewide TST dataset include 82 separate station/year ANOVAs and demonstrate that large-scale, existing volunteer and professional data with unpaired samples can show agreement of ~80% for all analyzed parameters (DO = 77%, pH = 79%, conductivity = 85%). In addition, to assess whether limiting variation within the source datasets increased the level of agreement between volunteers and professionals, data were analyzed at a local scale. Data from a single partner city, with increased controls on sampling times and locations and correction of a systematic bias in DO, confirmed this by showing an even greater agreement of 91% overall from 2009-2017 (DO = 91%, pH = 83%, conductivity = 100%). An experimental sampling dataset was analyzed and yielded similar results, indicating that existing datasets can be as accurate as experimental datasets designed with researcher supervision. Our findings underscore the reliability of large-scale citizen science monitoring datasets already in existence, and their potential value to scientific research and water management programs.

For decades citizen science has been used in environmental monitoring, and perhaps most commonly in water quality monitoring, as a tool to supplement professional data. Hundreds of volunteer monitoring efforts have generated datasets that cover large geographic areas over multiple years, and these large-scale datasets have been shown to be especially valuable for monitoring changes over time. Although volunteer water monitoring programs continue to grow worldwide, research shows that many of the existing datasets are still underutilized due to concerns about the accuracy of volunteer-collected data. An increasing number of “comparison studies” have attempted to address quality concerns by comparing volunteer data to professional data to assess relative accuracy, and the majority have reported that volunteer data are of a quality comparable to professional data. Nearly all of these studies, however, focused on a small subset of volunteer program data or data collected under experimental controls, and as such the results may not be applicable to existing, large-scale datasets with unknown controls and high levels of variation. Through a comprehensive look at water quality comparison studies to date, this review reveals a need for additional studies that specifically address the quality of highly variable, large-scale volunteer datasets and ultimately serve as a framework by which decades of volunteer efforts already in existence across the country can be better utilized.

The bermudagrass stem maggot, Atherigona reversura Villeneuve (Diptera: Muscidae), was first reported damaging bermudagrass Cynodon dactylon (L.) Pers grown for forage in 2010 in the southeastern United States. Injury results from individual larvae feeding internally on the vascular tissue just above the terminal node of the grass stem. Injury slows plant growth and reduces forage accumulation. To address the need for economic guidelines to manage this new pest, the relationship between the percent of stems damaged by bermudagrass stem maggot and forage yield was measured in commercial bermudagrass hay fields in northcentral Texas. Yield loss was estimated to be 9.97 kg/ha (8.90 lbs /acre) for each percentage of stems with bermudagrass stem maggot damage. This relationship was used to calculate economic injury levels for a range of hay market values and control costs. The impact of stem damage on protein content, energy, and digestibility of bermudagrass hay was also investigated. Although there was a significant trend for declining forage quality with increasing stem damage, stem damage explained very little of the model's variability.

A series of small ponds was constructed to determine whether dragonflies would oviposit in them. Four pond sizes - 0.3, 0.6, 0.9, and 1.2 m2 - were replicated and randomized in each of six blocks. Ponds in three of the blocks were planted with cattail (Typha sp.) and three with spike rush (Junca sp.). Sampling revealed that of 273 nymphs collected, 267 were Pantala flavescens (F.) and six were Orthemis ferruginea (F.), although adults of 15 other dragonfly species were seen in the study area. Dragonfly nymphs were not found in any of the smallest size of pond. Significantly more nymphs were found in ponds planted with cattail than rush (215 vs 52), but the nymphs grew larger in ponds with rushes. The mean number of nymphs was larger in the 1.2-m2 ponds (21.8) than in the 0.6-m2 ponds (8.7), while 0.9 m2 was intermediate (15.0). However, when the number of nymphs per unit area was compared, there were no differences between any of the pond sizes within a vegetation class -- cattail or rush. Between classes, more nymphs per unit area were in ponds planted with cattails. Because the one species of dominant dragonfly was not representative of distribution of dragonfly species in normal-sized ponds and probably was the only dragonfly found in any similar experiment, use of small reference ponds of these sizes was not feasible for assessing dragonfly diversity and abundance.

Tomato spotted wilt orthotospovirus (TSWV) is a major disease in peanut, Arachis hypogaea L., across peanut producing regions of the United States and elsewhere. Two thrips, Frankliniella fusca Hinds and Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), are considered important vectors of TSWV in peanut in the Southeast. We compared the efficiency of acquisition (by larvae) and transmission (adults) of both thrips species for TSWV (Texas peanut-strain) to leaf disks of peanut (Florunner), as well as to Impatiens walleriana Hook. f. (Dwarf White Baby) and Petunia hybrida Juss. 'Fire Chief' using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Both species were competent TSWV vectors in peanut and Impatiens, although F. fusca was the more efficient vector overall, i.e., virus acquisition and transmission rates for F. fusca averaged over several bioassays were 51.7 and 26.6%, respectively, compared with 20.0 and 15.3% for F. occidentalis. Neither species effectively transmitted this TSWV strain to Petunia (i.e., ≤3.6% transmission). We found statistically similar virus acquisition and transmission rates between both sexes for each species. We also detected no differences in TSWV-acquisition and transmission frequency between macropterous and brachypterous (short-wing) forms of F. fusca collected from a field population in south Texas. DAS-ELISA failed to detect low levels of TSWV in a few thrips that subsequently proved to be competent vectors.

Studies testing insecticidal compounds against thrips feeding in peanut were conducted at two sites in Texas—Stephenville (Erath County) in the northern region and Pearsall (Frio County) in the southern region. Products tested were aldicarb, acephate and disulfoton in at-plant, sidedress and split applications, and sulfur in split applications. Thrips populations were sampled weekly in terminals and flowers. A weekly census of both the number of terminals and flowers was used to establish absolute population densities of thrips. Control was obtained with all compounds tested except sulfur. However, control in northern Texas was reduced compared to studies conducted in previous years.

Prevalence of exposure to spirochetes, particularly Borrelia burgdorferi , in rodents of North Central Texas was determined using an indirect immunofluorescent assay. The Chi-square test was used to analyze positive sera reaction across season and tick distribution across rodent species. This test did not detect a seasonal significant difference of seropositive specimens (X 2 =2.45, df=3, Pu003e0.05). Percent tick infestation was significantly different across rodent species (X 2 =14.176, df=7, Pu003c0.05). Other data collected included 1) seasonal distribution of seropositive reactions in adult rodents, 2) distribution between trapsites of adult rodent positive serological reactions, 3) tick infestation organized by individual rodent stage and sex, 4) percent of each species seropositive, and 5) percent adult seropositive reactions per month.

Dinotefuran (DNT), imidacloprid (IMD), and thiamethoxam (THM) are commonly used neonicotinoid insecticides in a variety of agriculture operations. Although these insecticides help growers control pest infestation, the residual environmental occurrence of insecticides may cause unintended adverse ecological consequences to non-target species. In this study, the leaching behavior of DNT, IMD, and THM was investigated in soils collected from an active AgriLife Research Extension Center (AREC) vineyard. A series of column experiments were conducted to evaluate the leaching potential of insecticides under two experimental scenarios: a) individual pulse mode, and b) mixed pulse mode. In both scenarios, the breakthrough pattern of the insecticides in the mostly acidic to neutral vineyard soil clearly demonstrates medium to high leachability. Of the three insecticides studied for leaching, DNT has exhibited high leaching potential and exited the column with fewer pore volumes, whereas IMD was retained for longer, indicating lower leachability. Relative differences in leaching behavior of neonicotinoids could be attributed to their solubility with the leaching pattern IMD < THM < DNT showing strong correlation with increasing aqueous solubility 610 mg/L < 4100 mg/L < 39,830 mg/L. Triplicate column study experiments were conducted to evaluate the consistency of the breakthrough pattern of these insecticides. The repeatability of the breakthrough curves shows that both DNT and IMD are reproducible between runs, whereas, THM shows some inconsistency. Leaching behavior of neonicotinoid insecticides based on the leachability indices such as groundwater ubiquity score, relative leaching potential, and partitioning between different environmental matrices through a fugacity-based equilibrium criterion model clearly indicates that DNT may pose a greater threat to aquatic resources compared to IMD and THM.

Water quality impact due to excessive nutrients has been extensively studied. In recent years, however, micro-pollutants such as pharmaceuticals and hormonal products used in animal agriculture have added an additional impact to overall water quality. Pharmaceuticals used in the poultry, swine, beef, and dairy industries have been detected in various environmental matrices such as, soil, groundwater and surface water. In this study, 26 surface water samples were collected throughout the Bosque River Watershed (BRW) with samples representing a range of land use conditions and locations of major dairy operations. Samples were analyzed using commercially available Enzyme-Linked Immunosorbent Assay test. Of the 26 samples, three samples consistently tested positive for monensin antibiotic with concentration ranging from 0.30 to 3.41 μg/L. These three samples were collected from sites that received varying amount of agriculture wastes (11.7% to 31.3%) and located downstream from sites associated with moderate levels of animal agriculture. The preliminary results suggest that there is a potential for monensin occurrence in the BRW, although initial findings indicate only very low levels.

Pierce's disease (PD) is a fatal disease of grapevines which results from an infection by the plant pathogen Xyllela fastidiosa. This bacterium grows in the xylem (water-conducting) vessels of the plant blocking movement of water. PD can kill vines in one year and poses a serious threat to both the California and the expanding Texas wine industries. Bacteria are vectored from one vine to the next by a number of xylem feeding insect species. Of these, the Glassy-winged Sharpshooter (GWSS) is considered to be the primary xylem feeding insect in Texas vineyards. An extensive database of the xylem-feeding population frequencies was collected by USDA-APHIS for Texas vineyards over multiple years. This project focused on a subset of data, GWSS frequencies within 25 vineyards in Edwards Plateau located in central Texas. The proposed model investigates the natural population dynamics and the decline in GWSS, likely the result of pest management campaigns on the insects within the region. The model is a delay Gompertz differential equation with harvesting and immigration terms, and we use the data to estimate the model parameters.

Epidemiological studies of Pierce's disease (PD) can be confounded by a lack of taxonomic detail on the bacterial causative agent, Xylella fastidiosa (Xf). PD in grape is caused by strains of Xylella fastidiosa subsp. fastidiosa, but is not caused by other subspecies of Xf that typically colonize plants other than grape. Detection assays using ELISA and qPCR are effective at detecting and quantifying Xf presence or absence, but offer no information on Xf subspecies or strain identity. Surveying insects or host plants for Xf by current ELISA or qPCR methods provides only presence/absence and quantity information for any and all Xf subspecies, potentially leading to false assessments of disease threat. This study uses a series of adjacent-hybridizing DNA melt analysis probes that are capable of efficiently discriminating Xf subspecies and strain relationships in rapid real-time PCR reactions.

We report an inexpensive, high-throughput method for isolating DNA from insect and plant samples for the purpose of detecting Xylella fastidiosa infection. Existing methods often copurify inhibitors of DNA polymerases, limiting their usefulness for PCR-based detection assays. When compared to commercially available kits, the method provides enhanced pathogen detection at a fraction of the cost.

Xylella fastidiosa is a plant pathogenic bacterium that causes many economically important agricultural diseases and is transmitted by the glassy-winged sharpshooter, Homalodisca vitripennis (Hemiptera: Cicadellidae). Efficient detection of X. fastidiosa in field collected H. vitripennis in an area-wide management program can contribute to risk assessment associated with insect presence in vineyards. Prior to conducting molecular assays for detection of X. fastidiosa in individual insects, H. vitripennis must be removed from yellow sticky traps with a solvent such as orange oil. In this study, we determined the effect of orange oil concentration on extraction of individual H. vitripennis following trap removal on detection of X. fastidiosa by qRT-PCR. In a ten-fold dilution series of orange oil, increasing amounts of orange oil caused decreasing levels of X. fastidiosa detection in standardized positive samples. Additionally, tests on the effects of Stickem® brand trap adhesive on qRT-PCR and development of methods which lowered the concentration of orange oil often present in field samples determined the point where detection of X. fastidiosa was negatively impacted. These results benefit the monitoring and screening for Xylella fastidiosa from leafhoppers collected on sticky cards used in regulatory area-wide management.

The goal of this project was to analyze a large collection of insect trap data accumulated by the Texas Pierce's Disease Research and Education Program. The traps were set in grape, Vitis, vineyards across Texas to monitor the abundance and distribution of xylem fluid-feeding insects that may vector Pierce's disease. This study evaluated the three most abundant xylem fluid-feeding insects in Texas vineyards: the glassy-winged sharpshooter, Homalodisca vitripennis (Germar); a smaller green sharpshooter, Graphocephala versuta (Say); and the sunflower spittlebug, Clastoptera xanthocephala Germar. Canonical Correspondence Analysis was used to analyze insect abundance against environmental gradients of ecoregion, elevation, annual precipitation, and cold hardiness from 2003-2007 in each of 40 vineyards. Canonical Correspondence Analysis showed that distribution of species along environmental gradients differed significantly (p = 0.001) and the environmental gradients explained almost 67% of the variability in insect distribution across the state. The Canonical Correspondence Analysis plot also suggested niche differences among these insect species.

The glassy-winged sharpshooter, Homalodisca vitripeninis Germar (Hemiptera: Cicadellidae), is a xylophagous insect that is an endemic pest of several economically important plants in Texas. H. vitripennis is the main vector of Xylella fastidiosa Wells (Xanthomonadales: Xanthomonadaceae), the bacterium that causes Pierce's disease of grapevine and can travel long distances putting much of Texas grape production at risk. Understanding the movement of H. vitripennis populations capable of transmitting X. fastidiosa into Pierce's-disease-free areas is critical for developing a management program for Pierce's disease. To that end, the USDA-APHIS has developed a program to sample vineyards across Texas to monitor populations of H. vitripennis. From this sampling, H. vitripennis collected during 2005 and 2006 over the months of May, June, and July from eight vineyards in different regions of Texas were recovered from yellow sticky traps and tested for the presence of X. fastidiosa. The foregut contents were vacuum extracted and analyzed using RT-PCR to determine the percentage of H. vitripennis within each population that harbor X. fastidiosa and have the potential to transmit this pathogen. H. vitripennis from vineyards known to have Pierce's disease routinely tested positive for the presence of X. fastidiosa. While almost all H. vitripennis collected from vineyards with no history of Pierce's disease tested negative for the presence of the pathogen, three individual insects tested positive. Furthermore, all three insects were determined, by DNA sequencing, to be carrying a strain of X. fastidiosa homologous to known Pierce's disease strains, signifying them as a risk factor for new X. fastidiosa infections.