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Automated Trichome Counting In Soybean Using Advanced Image‐Processing Techniques, Seyed Vahid Mirnezami, Therin Young, Teshale Assefa, Shelby Prichard, Koushik Nagasubramanian, Kulbir Sandhu, Soumik Sarkar, Sriram Sundararajan, Matthew E. O'Neal, Baskar Ganapathysubramanian, Arti Singh Jul 2020

Automated Trichome Counting In Soybean Using Advanced Image‐Processing Techniques, Seyed Vahid Mirnezami, Therin Young, Teshale Assefa, Shelby Prichard, Koushik Nagasubramanian, Kulbir Sandhu, Soumik Sarkar, Sriram Sundararajan, Matthew E. O'Neal, Baskar Ganapathysubramanian, Arti Singh

Mechanical Engineering Publications

Premise Trichomes are hair‐like appendages extending from the plant epidermis. They serve many important biotic roles, including interference with herbivore movement. Characterizing the number, density, and distribution of trichomes can provide valuable insights on plant response to insect infestation and define the extent of plant defense capability. Automated trichome counting would speed up this research but poses several challenges, primarily because of the variability in coloration and the high occlusion of the trichomes.

Methods and Results We developed a simplified method for image processing for automated and semi‐automated trichome counting. We illustrate this process using 30 leaves from ...


Targeted Suppression Of Soybean Bag6‐Induced Cell Death In Yeast By Soybean Cyst Nematode Effectors, Jianying Wang, Greg Yeckel, Pramod K. Kandoth, Lakmini Wasala, Richard S. Hussey, Eric L. Davis, Thomas J. Baum, Melissa G. Mitchum Jan 2020

Targeted Suppression Of Soybean Bag6‐Induced Cell Death In Yeast By Soybean Cyst Nematode Effectors, Jianying Wang, Greg Yeckel, Pramod K. Kandoth, Lakmini Wasala, Richard S. Hussey, Eric L. Davis, Thomas J. Baum, Melissa G. Mitchum

Plant Pathology and Microbiology Publications

While numerous effectors that suppress plant immunity have been identified from bacteria, fungi, and oomycete pathogens, relatively little is known for nematode effectors. Several dozen effectors have been reported from the soybean cyst nematode (SCN). Previous studies suggest that a hypersensitive response‐like programmed cell death is triggered at nematode feeding sites in soybean during an incompatible interaction. However, virulent SCN populations overcome this incompatibility using unknown mechanisms. A soybean BAG6 (Bcl‐2 associated anthanogene 6) gene previously reported by us to be highly up‐regulated in degenerating feeding sites induced by SCN in a resistant soybean line was attenuated ...


Screening Soybean Cyst Nematode Effectors For Their Ability To Suppress Plant Immunity, Gennady Pogorelko, Jianying Wang, Parijat S. Juvale, Melissa G. Mitchum, Thomas J. Baum Jan 2020

Screening Soybean Cyst Nematode Effectors For Their Ability To Suppress Plant Immunity, Gennady Pogorelko, Jianying Wang, Parijat S. Juvale, Melissa G. Mitchum, Thomas J. Baum

Plant Pathology and Microbiology Publications

The soybean cyst nematode (SCN), Heterodera glycines , is one of the most destructive pathogens of soybeans. SCN is an obligate and sedentary parasite that transforms host plant root cells into an elaborate permanent feeding site, a syncytium. Formation and maintenance of a viable syncytium is an absolute requirement for nematode growth and reproduction. In turn, sensing pathogen attack, plants activate defence responses and may trigger programmed cell death at the sites of infection. For successful parasitism, H. glycines must suppress these host defence responses to establish and maintain viable syncytia. Similar to other pathogens, H. glycines engages in these molecular ...


What Are The Consequences Of Resistance? Exploring The Impacts Of Insecticide And Host-Plant Resistance For Insect Pest Management, Ashley Nicole Dean Jan 2019

What Are The Consequences Of Resistance? Exploring The Impacts Of Insecticide And Host-Plant Resistance For Insect Pest Management, Ashley Nicole Dean

Graduate Theses and Dissertations

Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), has been a prominent insect pest in the northcentral region since 2000. Insecticides are the primary management tactic for this pest, but some populations of soybean aphid resistant to pyrethroid insecticides have been reported since 2015. This increases the impact of soybean aphid on soybean, Glycine max (L.) Merr (Fabales: Fabaceae), production, which is already challenged by higher input costs, declining market value, and unpredictable weather. Soybean aphid-resistant varieties are available to farmers but limited to genetic backgrounds that exclude herbicide-tolerance. This is a significant barrier to adoption since farmers rely on herbicide-tolerant ...


Management Of Insecticide-Resistant Soybean Aphids In The Upper Midwest Of The United States, Robert L. Koch, Erin W. Hodgson, Janet J. Knodel, Adam J. Varenhorst, Bruce D. Potter Jan 2018

Management Of Insecticide-Resistant Soybean Aphids In The Upper Midwest Of The United States, Robert L. Koch, Erin W. Hodgson, Janet J. Knodel, Adam J. Varenhorst, Bruce D. Potter

Entomology Publications

Since the first observation of soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in North America in 2000, it has become the most economically damaging insect of soybean in the Upper Midwest of the United States. For the last 17 yr, soybean aphid management has relied almost entirely on the use of foliar-applied broad-spectrum insecticides. However, in 2015 in Minnesota, failures of foliar-applied pyrethroid insecticides were reported and pyrethroid resistance was confirmed with laboratory bioassays using lambda-cyhalothrin and bifenthrin. In 2016 and 2017, further reports of failures of pyrethroid insecticides and/or laboratory confirmation of resistance occurred in Iowa, North Dakota ...


Reduced Fitness Of Virulent Aphis Glycines (Hemiptera: Aphididae) Biotypes May Influence The Longevity Of Resistance Genes In Soybean, Adam J. Varenhorst, Michael T. Mccarville, Matthew E. O'Neal Sep 2015

Reduced Fitness Of Virulent Aphis Glycines (Hemiptera: Aphididae) Biotypes May Influence The Longevity Of Resistance Genes In Soybean, Adam J. Varenhorst, Michael T. Mccarville, Matthew E. O'Neal

Entomology Publications

Sustainable use of insect resistance in crops require insect resistance management plans that may include a refuge to limit the spread of virulence to this resistance. However, without a loss of fitness associated with virulence, a refuge may not prevent virulence from becoming fixed within a population of parthenogenetically reproducing insects like aphids. Aphid-resistance in soybeans (i.e., Rag genes) prevent outbreaks of soybean aphid (Aphis glycines), yet four biotypes defined by their capacity to survive on aphid-resistant soybeans (e.g., biotype-2 survives on Rag1 soybean) are found in North America. Although fitness costs are reported for biotype-3 on aphid ...


Survey Of Soybean Insect Pollinators: Community Identification And Sampling Method Analysis, K. A. Gill, M. E. O'Neal Jun 2015

Survey Of Soybean Insect Pollinators: Community Identification And Sampling Method Analysis, K. A. Gill, M. E. O'Neal

Entomology Publications

Soybean, Glycine max (L.) Merrill, flowers can be a source of nectar and pollen for honey bees, Apis mellifera L. (Hymenoptera: Apidae), wild social and solitary bees (Hymenoptera: Apoidea), and flower-visiting flies (Diptera). Our objectives were to describe the pollinator community in soybean fields, determine which sampling method is most appropriate for characterizing their abundance and diversity, and gain insight into which pollinator taxa may contact soybean pollen. We compared modified pan traps (i.e., bee bowls), yellow sticky traps, and sweep nets for trapping pollinators in Iowa soybean fields when soybeans were blooming (i.e., reproductive stages R1–R6 ...


Aboveground Feeding By Soybean Aphid, Aphis Glycines, Affects Soybean Cyst Nematode, Heterodera Glycines, Reproduction Belowground, Michael T. Mccarville, David H. Soh, Gregory L. Tylka, Matthew E. O'Neal Jan 2014

Aboveground Feeding By Soybean Aphid, Aphis Glycines, Affects Soybean Cyst Nematode, Heterodera Glycines, Reproduction Belowground, Michael T. Mccarville, David H. Soh, Gregory L. Tylka, Matthew E. O'Neal

Entomology Publications

Heterodera glycines is a cyst nematode that causes significant lost soybean yield in the U.S. Recent studies observed the aphid Aphis glycines and H. glycines interacting via their shared host, soybean, Glycine max. A greenhouse experiment was conducted to discern the effect ofA. glycines feeding on H. glycines reproduction. An H. glycines-susceptible cultivar, Kenwood 94, and a resistant cultivar, Dekalb 27–52, were grown in H. glycines-infested soil for 30 and 60 d. Ten days after planting, plants were infested with either zero, five, or ten aphids. At 30 and 60 d, the number of H ...


Insect Pollinators In Corn And Soybean Agricultural Fields, Michael Joseph Wheelock Jan 2014

Insect Pollinators In Corn And Soybean Agricultural Fields, Michael Joseph Wheelock

Graduate Theses and Dissertations

Iowa's landscape is dominated by row crop agriculture with the majority of acres being in corn and soybean production, and as a result is spatially uniform and functionally homogenized. In landscapes dominated by agriculture, such as those found in Iowa, the availability of mass flowering crop species show strong positive effects on the density of generalist, native pollinators. While soybean, a self-pollinated plant, and corn, a wind pollinated plant, do not require physical pollination for fruit production, they can be a source of nectar and/or pollen for insect pollinators. The first objective is to develop methodology to accurately ...


Effects Of Rag1 On The Preference And Performance Of Soybean Defoliators, Robert F. Bruner, Erin W. Hodgson, Aaron J. Gassmann Dec 2013

Effects Of Rag1 On The Preference And Performance Of Soybean Defoliators, Robert F. Bruner, Erin W. Hodgson, Aaron J. Gassmann

Entomology Publications

The Rag1 gene confers antibiotic resistance to soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), and in 2010, varieties expressing Rag1 were released for commercial use in the United States. We do not know how Rag1 varieties will influence the broader community of defoliating insects that inhabit soybean fields. In 2010 and 2011, the preference and performance of pest insects that defoliate soybeans [Glycines max (L.) Merr] were tested using Rag1 and aphidsusceptible varieties. Three coleopterans and four lepidopterans were used: northern corn rootworm, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae); southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae); bean leaf beetle, Ceratoma trifurcata ...


Measuring The Benefit Of Biological Control For Single Gene And Pyramided Host Plant Resistance For Aphis Glycines (Hemiptera: Aphididae) Management, Michael T. Mccarville, Matthew E. O'Neal Oct 2012

Measuring The Benefit Of Biological Control For Single Gene And Pyramided Host Plant Resistance For Aphis Glycines (Hemiptera: Aphididae) Management, Michael T. Mccarville, Matthew E. O'Neal

Entomology Publications

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an economically important pest in the north central United States. In the state of Iowa, economically damaging populations occurred in seven of 11 growing seasons from 2001 to 2011. The high frequency and economic impact of the soybean aphid makes it an ideal candidate for management by using host plant resistance. We compared an aphid-susceptible line to near-isolines that contain Rag1 and Rag2, both alone and pyramided together, to suppress aphid populations and protect yield. Each of four near-isolines, were artificially infested with aphids and grown in small plots in which ...


Soybean Aphid (Hemiptera: Aphididae) Development On Soybean With Rag1 Alone, Rag2 Alone, And Both Genes Combined, Shaylyn Lena Wiarda, Walter R. Fehr, Matthew E. O'Neal Jan 2012

Soybean Aphid (Hemiptera: Aphididae) Development On Soybean With Rag1 Alone, Rag2 Alone, And Both Genes Combined, Shaylyn Lena Wiarda, Walter R. Fehr, Matthew E. O'Neal

Entomology Publications

Aphis glycines Matsumura (Hemiptera: Aphididae) can reduce the yield of aphidsusceptible soybean (Glycine max (L.) Merrill) cultivars. The Rag1 and Rag2 genes confer resistance to some biotypes of A. glycines. These genes individually can limit population growth of A. glycines and prevent yield loss. The impact of these genes when combined is not known. We compared the development of A. glycines on soybean with Rag1 alone (R1/S2), Rag2 alone (S1/R2), both genes combined (R1/R2), or neither gene (S1/S2). In addition, we determined the impact of different levels of aphid infestation on seed yield. The genotypes were ...


Distribution Of Two Rotation-Resistant Corn Pests In Eastern Iowa And Effects Of Soybean Varieties On Biology Of Diabrotica Virgifera Virgifera, Michael Wilson Dunbar Jan 2011

Distribution Of Two Rotation-Resistant Corn Pests In Eastern Iowa And Effects Of Soybean Varieties On Biology Of Diabrotica Virgifera Virgifera, Michael Wilson Dunbar

Graduate Theses and Dissertations

The western corn rootworm Diabrotica virgifera virgifera LeConte (WCR) and the northern corn rootworm Diabrotica barberi Smith & Lawrence (NCR) are two significant insect pests of corn in North America. Both species have adapted to crop rotation in the Midwest, NCR through extended diapause and WCR by ovipositing in alternative crops. We conducted surveys during 2008 and 2009 to collect data on the presence of rotation-resistant NCR and WCR. Data were collected by placing Pherocon AM sticky traps in soybean and corn fields and by placing emergence cages in corn fields. Rotation-resistant WCR was most common in the northeastern and east-central ...


What Is The Economic Threshold Of Soybean Aphids (Hemiptera: Aphididae) In Enemy-Free Space?, Michael T. Mccarville, Charles Kanobe, Gustavo C. Macintosh, Matthew E. O'Neal Jan 2011

What Is The Economic Threshold Of Soybean Aphids (Hemiptera: Aphididae) In Enemy-Free Space?, Michael T. Mccarville, Charles Kanobe, Gustavo C. Macintosh, Matthew E. O'Neal

Entomology Publications

Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a serious pest of soybean, Glycine max (L.) Merr., in the North Central United States. Current management recommendations rely on the application of insecticides based on an economic threshold (ET) of 250 aphids per plant. Natural enemies are important in slowing the increase of aphid populations and can prevent them from reaching levels that can cause economic losses. However, biological control of A. glycines is inconsistent and can be affected negatively by the intensity of agricultural activity. We measured the impact of a natural-enemy-free environment on the capacity of the current ET ...


Reduction In Common Milkweed (Asclepias Syriaca) Occurrence In Iowa Cropland From 1999 To 2009, Robert G. Hartzler Dec 2010

Reduction In Common Milkweed (Asclepias Syriaca) Occurrence In Iowa Cropland From 1999 To 2009, Robert G. Hartzler

Agronomy Publications

The role of common milkweed in the lifecycle of the monarch butterfly has increased interest in the presence of this weed in the north central United States. An initial survey conducted in 1999 found that low densities of common milkweed occurred in approximately 50% of Iowa corn and soybean fields. In 2009, common milkweed was present in only 8% of surveyed fields, and the area within infested fields occupied by common milkweed was reduced by approximately 90% compared to 1999. The widespread adoption of glyphosate resistant corn and soybean cultivars and the reliance on post-emergence applications of glyphosate for weed ...


Insect-Mediated Cross-Pollination In Soybean [Glycine Max (L.) Merrill] : I. Agronomic Performance, E. Ortiz-Perez, S. R. Cianzio, H. Wiley, Harry T. Horner, W. H. Davis, R. G. Palmer Jan 2007

Insect-Mediated Cross-Pollination In Soybean [Glycine Max (L.) Merrill] : I. Agronomic Performance, E. Ortiz-Perez, S. R. Cianzio, H. Wiley, Harry T. Horner, W. H. Davis, R. G. Palmer

Genetics, Development and Cell Biology Publications

In soybean, manual cross-pollination to produce large quantities of F1 hybrid seed for yield trials is difficult and time-consuming. Conversely, insect-mediated cross-pollination has been shown to produce large quantities of hybrid seed in soybean and could facilitate the identification of heterotic patterns. The objective of our study was: (1) evaluate F1hybrid soybean plants from single crosses for yield and agronomic traits over several environments and (2) compare hybrid performance of the single crosses to lines developed from three-way crosses and backcrosses. In 2003, F1 seed of single-crosses and their parent lines were evaluated in replicated experiments ...


Insect-Mediated Seed-Set Evaluation Of 21 Soybean Lines Segregating For Male Sterility At 10 Different Loci, E. Ortiz-Perez, Harry T. Horner, S. J. Hanlin, R. G. Palmer Dec 2006

Insect-Mediated Seed-Set Evaluation Of 21 Soybean Lines Segregating For Male Sterility At 10 Different Loci, E. Ortiz-Perez, Harry T. Horner, S. J. Hanlin, R. G. Palmer

Genetics, Development and Cell Biology Publications

The first requirement to establish a successful hybrid soybean program is the availability of a stable male-sterile, female-fertile system. Male sterility has been an important tool in soybean breeding programs to improve traits such as yield, seed-protein and seed-oil content, and seed size. However, improvement of seed-set per se on male-sterile plants has not been an important breeding objective. The evaluation of the out-crossing potential of the available male-sterile, female-fertile soybean lines is crucial to determine the future of hybrid soybean. The objective of this study was to evaluate seed-set among 21 soybean lines segregating for male sterility at 10 ...


Corn Phenology Influences Diabrotica Virgifera Virgifera Emigration And Visitation To Soybean In, Matthew E. O'Neal, D. A. Landis, J. R. Miller Feb 2004

Corn Phenology Influences Diabrotica Virgifera Virgifera Emigration And Visitation To Soybean In, Matthew E. O'Neal, D. A. Landis, J. R. Miller

Matthew E. O'Neal

We used two types of laboratory apparatus to test whether rotation-resistant and wild-type Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) responded differently to corn phenology. Beetles from Nebraska where injury to rotated corn has not been reported were defined as wild type, and beetles from Illinois where injury to rotated corn is common represented “rotation-resistant“ populations. A two-chamber emigration arena assayed propensity of both populations to leave corn during and after anthesis. A side-arm olfactometer tested whether the relative attraction of beetles to soybean versus corn was influenced by corn phenology. Beetle origin did not influence departure from corn of varying ...


An Inexpensive, Accurate Method For Measuring Leaf Area And Defoliation Through Digital Image Analysis, Matthew E. O'Neal, Douglas A. Landis, Rufus Isaacs Dec 2002

An Inexpensive, Accurate Method For Measuring Leaf Area And Defoliation Through Digital Image Analysis, Matthew E. O'Neal, Douglas A. Landis, Rufus Isaacs

Matthew E. O'Neal

We report a protocol using a common desk-top scanner and public domain software for measuring existing leaf area and leaf area removed as a result of herbivory. We compared the accuracy and precision of this method to that of a standard leaf area meter. Both methods were used to measure metal disks of a known area, the area of soybean (Glycine max L.) leaves, and the area removed by simulating leaf feeding with a hole-punch. We varied the amount of injury across a low, medium, and high degree of simulated feeding. The mean area of 10 cm2 and 50 cm2 ...


Influence Of Herbicide Application To Soybeans On Soybean Cyst Nematode Egg Hatching, Brian C. Levene, Michael D. K. Owen, Gregory L. Tylka Sep 1998

Influence Of Herbicide Application To Soybeans On Soybean Cyst Nematode Egg Hatching, Brian C. Levene, Michael D. K. Owen, Gregory L. Tylka

Plant Pathology and Microbiology Publications

The hatching of Heterodera glycines eggs in soybean root exudates collected after postemergence application of three herbicides, and the hatching potential of H. glycines eggs from females feeding on herbicide-treated plants, were measured in vitro. Hatching in all root exudate solutions (RES) was greater than in deionized water but less than in 0.003 M ZnSO[sub4] solution. Filtering RES with a 0.22-[mu]m-filter increased H. glycines hatching in RES. Application of acifluorfen, bentazon, and lactofen to foliage of soybean plants inhibited hatching of H. glycines eggs from the same plants. Hatching in RES from the different herbicide-treated ...


Responses Of Heterodera Glycines Populations To A Postemergence Herbicide Mixture And Simulated Insect Defoliation, J. A. Browde, G. L. Tylka, L. P. Pedigo, M. D. K. Owen Dec 1994

Responses Of Heterodera Glycines Populations To A Postemergence Herbicide Mixture And Simulated Insect Defoliation, J. A. Browde, G. L. Tylka, L. P. Pedigo, M. D. K. Owen

Plant Pathology and Microbiology Publications

Effects of a mixture of the postemergence herbicides acifluorfen and bentazon, and simulated defoliation expected from green cloverworm on population densities of Heterodera glycines were determined in field plots in Iowa. The herbicide mixture and defoliation each suppressed soybean growth. Population densities of H. glycines were generally lower in herbicide-treated than untreated plots. Population densities of the nematode were unaffected by defoliation in 1988 and 1990-91, but were increased by the treatment in 1989. Key words: acifluorfen, bentazon, defoliation, Glycine max, green cloverworm, herbicide, Heterodera glycines, nematode, Plathypena scabra, postemergence herbicides, soybean, soybean cyst nematode.