1
|
Menger JP, Ribeiro AV, Potter BD, Valmorbida I, Hodgson EW, Knodel JJ, Koch RL. Lack of Evidence for Fitness Costs in Soybean Aphid (Hemiptera: Aphididae) With Resistance to Pyrethroid Insecticides in the Upper Midwest Region of the United States. JOURNAL OF ECONOMIC ENTOMOLOGY 2022; 115:1191-1202. [PMID: 35766410 DOI: 10.1093/jee/toac096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Indexed: 06/15/2023]
Abstract
Twenty years after the arrival of soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in the United States, it remains the most economically important arthropod pest of soybean in the Upper Midwest Region. After years of repeated and sustained insecticidal pressures placed on the aphid, resistance to the pyrethroid class of insecticides has been documented in multiple years over a large geographic area. In this study, the fitness of aphid isolates displaying resistant and susceptible phenotypes to λ-cyhalothrin were compared within several experiments over three soybean-growing seasons. Rates of population increase were evaluated on whole plants in the greenhouse, intrinsic rates of increase were calculated from leaf discs in the laboratory, and aphid size and asymmetry were compared through tibial measurements. No evidence of a fitness cost associated with the resistant phenotype was seen in any of our experiments. In contrast, individual resistant isolates occasionally supported significantly higher fitness values than some susceptible isolates. Additionally, a pooled analysis comparing resistant and susceptible phenotypes across years and isolates revealed that, on average, the resistant phenotype had significantly higher fitness values than the susceptible phenotype in most experiments. The lack of reproductive fitness costs associated with the pyrethroid-resistant phenotype raises concerns for longevity of pyrethroid use in soybean aphid management.
Collapse
Affiliation(s)
- James P Menger
- Department of Entomology, University of Minnesota, 1980 Folwell Avenue, Saint Paul, MN 55108, USA
| | - Arthur V Ribeiro
- Department of Entomology, University of Minnesota, 1980 Folwell Avenue, Saint Paul, MN 55108, USA
| | - Bruce D Potter
- University of Minnesota Southwest Research and Outreach Center, 23669 130th Street, Lamberton, MN 56152, USA
| | - Ivair Valmorbida
- Department of Entomology, Iowa State University, ATRB, Ames, IA 50011, USA
| | - Erin W Hodgson
- Department of Entomology, Iowa State University, ATRB, Ames, IA 50011, USA
| | - Janet J Knodel
- Department of Plant Pathology, North Dakota State University, 210 Walster Hall, Fargo, ND 58102, USA
| | - Robert L Koch
- Department of Entomology, University of Minnesota, 1980 Folwell Avenue, Saint Paul, MN 55108, USA
| |
Collapse
|
2
|
Banerjee A, Valmorbida I, O’Neal ME, Parshad R. Exploring the Dynamics of Virulent and Avirulent Aphids: A Case for a 'Within Plant' Refuge. JOURNAL OF ECONOMIC ENTOMOLOGY 2022; 115:279-288. [PMID: 35139216 PMCID: PMC8827328 DOI: 10.1093/jee/toab218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Indexed: 06/14/2023]
Abstract
The soybean aphid, Aphis glycines (Hemiptera: Aphididae), is an invasive pest that can cause severe yield loss to soybeans in the North Central United States. A tactic to counter this pest is the use of aphid-resistant soybean varieties. However, the frequency of virulent biotypes that can survive on resistant varieties is expected to increase as more farmers use these varieties. Soybean aphids can alter soybean physiology primarily by two mechanisms, feeding facilitation, and the obviation of resistance, favoring subsequent colonization by additional conspecifics. We developed a nonlocal, differential equation population model to explore the dynamics of these biological mechanisms on soybean plants coinfested with virulent and avirulent aphids. We then use demographic parameters from laboratory experiments to perform numerical simulations via the model. We used this model to determine that initial conditions are an important factor in the season-long cooccurrence of both biotypes. The initial population of both biotypes above the resistance threshold or avirulent aphid close to resistance threshold and high virulent aphid population results in coexistence of the aphids throughout the season. These simulations successfully mimicked aphid dynamics observed in the field- and laboratory-based microcosms. The model showed an increase in colonization of virulent aphids increases the likelihood that aphid resistance is suppressed, subsequently increasing the survival of avirulent aphids. This interaction produced an indirect, positive interaction between the biotypes. These results suggest the potential for a 'within plant' refuge that could contribute to the sustainable use of aphid-resistant soybeans.
Collapse
Affiliation(s)
- Aniket Banerjee
- Department of Mathematics, Iowa State University, Ames, IA, USA
| | | | | | - Rana Parshad
- Department of Mathematics, Iowa State University, Ames, IA, USA
| |
Collapse
|
3
|
Natukunda MI, Hohenstein JD, McCabe CE, Graham MA, Qi Y, Singh AK, MacIntosh GC. Interaction between Rag genes results in a unique synergistic transcriptional response that enhances soybean resistance to soybean aphids. BMC Genomics 2021; 22:887. [PMID: 34895143 PMCID: PMC8665634 DOI: 10.1186/s12864-021-08147-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 11/03/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Pyramiding different resistance genes into one plant genotype confers enhanced resistance at the phenotypic level, but the molecular mechanisms underlying this effect are not well-understood. In soybean, aphid resistance is conferred by Rag genes. We compared the transcriptional response of four soybean genotypes to aphid feeding to assess how the combination of Rag genes enhanced the soybean resistance to aphid infestation. RESULTS A strong synergistic interaction between Rag1 and Rag2, defined as genes differentially expressed only in the pyramid genotype, was identified. This synergistic effect in the Rag1/2 phenotype was very evident early (6 h after infestation) and involved unique biological processes. However, the response of susceptible and resistant genotypes had a large overlap 12 h after aphid infestation. Transcription factor (TF) analyses identified a network of interacting TF that potentially integrates signaling from Rag1 and Rag2 to produce the unique Rag1/2 response. Pyramiding resulted in rapid induction of phytochemicals production and deposition of lignin to strengthen the secondary cell wall, while repressing photosynthesis. We also identified Glyma.07G063700 as a novel, strong candidate for the Rag1 gene. CONCLUSIONS The synergistic interaction between Rag1 and Rag2 in the Rag1/2 genotype can explain its enhanced resistance phenotype. Understanding molecular mechanisms that support enhanced resistance in pyramid genotypes could facilitate more directed approaches for crop improvement.
Collapse
Affiliation(s)
- Martha I. Natukunda
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011 USA
| | - Jessica D. Hohenstein
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011 USA
| | - Chantal E. McCabe
- Corn Insects and Crop Genetics Research, USDA-ARS, Ames, IA 50011 USA
| | - Michelle A. Graham
- Corn Insects and Crop Genetics Research, USDA-ARS, Ames, IA 50011 USA
- Department of Agronomy, Iowa State University, Ames, IA 50011 USA
| | - Yunhui Qi
- Department of Statistics, Iowa State University, Ames, IA 50011 USA
| | - Asheesh K. Singh
- Department of Agronomy, Iowa State University, Ames, IA 50011 USA
| | - Gustavo C. MacIntosh
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011 USA
| |
Collapse
|
4
|
Tilmon KJ, Michel A, O'Neal ME. Aphid resistance is the future for soybean production, and has been since 2004: efforts towards a wider use of host plant resistance in soybean. CURRENT OPINION IN INSECT SCIENCE 2021; 45:53-58. [PMID: 33545434 DOI: 10.1016/j.cois.2021.01.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
The soybean aphid (Aphis glycines) is an important pest of soybeans in the Midwestern US. The first aphid resistance genes were identified in the early 21st century and resistant varieties have been commercially available for 10 years, but have been very underutilized. Major seed companies have avoided commercializing aphid resistant soybean varieties for conventional farmers (i.e., not organic), in part because of the discovery of virulent biotypes in North America. The emergence of soybean aphid populations resistant to insecticides creates a greater incentive for the use of host plant resistance. New research on aphid genetics and markers, plant gene expression and in-plant refuges, suggest important avenues for insect resistance management (IRM) which may encourage more widescale commercialization of this valuable pest management tool.
Collapse
Affiliation(s)
- Kelley J Tilmon
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Ave., Wooster, OH, USA.
| | - Andy Michel
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Ave., Wooster, OH, USA; The Center for Applied Plant Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Ave., Wooster, OH, USA
| | | |
Collapse
|
5
|
Esquivel CJ, Canas LA, Tilmon K, Michel AP. Evaluating the role of insecticidal seed treatment and refuge for managing soybean aphid virulence. PEST MANAGEMENT SCIENCE 2021; 77:2924-2932. [PMID: 33624388 DOI: 10.1002/ps.6328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 01/15/2021] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Managing insect virulence can extend the durability of host-plant resistant crops. Genetically modified resistant crops continue to be successful because of insect-resistant management strategies that delay resistance such as multiple toxins and a susceptible refuge. These strategies may also be useful for host-plant resistant crops, but more research is needed on their applicability. We investigated the interaction between a susceptible refuge and an insecticidal seed treatment to manage virulence in the soybean aphid. We tested four scenarios of an insecticidal seed treatment (plus an untreated control) in a microcosm containing 25% aphid-susceptible (refuge) and 75% aphid-resistant soybeans. Independent cohorts of plants were infested every week with avirulent and virulent aphids at equal frequencies. We used a molecular marker to estimate the change in virulence frequency across different plant maturities (from 7 to 42 days after planting). RESULTS The presence of an insecticidal seed treatment on either the susceptible or resistant soybean decreased the overall population size of the soybean aphid. However, the insecticidal seed treatment impacted both virulent and avirulent aphids similarly, and only altered frequencies in favor of virulence when the sole susceptible plant (i.e., refuge) was treated. CONCLUSION Under our experimental conditions, the frequency of avirulent aphids persisted with the use of a refuge. Although an insecticidal seed treatment decreased the overall aphid population size, it did not appear to benefit virulence management. © 2021 Society of Chemical Industry.
Collapse
Affiliation(s)
- Carlos J Esquivel
- Department of Entomology, CFAES Wooster Campus, The Ohio State University, Wooster, OH, USA
| | - Luis A Canas
- Department of Entomology, CFAES Wooster Campus, The Ohio State University, Wooster, OH, USA
| | - Kelley Tilmon
- Department of Entomology, CFAES Wooster Campus, The Ohio State University, Wooster, OH, USA
| | - Andy P Michel
- Department of Entomology, CFAES Wooster Campus, The Ohio State University, Wooster, OH, USA
- Center of Applied Plant Sciences, The Ohio State University, Wooster, OH, USA
| |
Collapse
|
6
|
Dean AN, Niemi JB, Tyndall JC, Hodgson EW, O'Neal ME. Developing a decision-making framework for insect pest management: a case study using Aphis glycines (Hemiptera: Aphididae). PEST MANAGEMENT SCIENCE 2021; 77:886-894. [PMID: 32949094 PMCID: PMC7821323 DOI: 10.1002/ps.6093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/20/2020] [Accepted: 09/19/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The profitability of farming varies based on factors such as a crop's market value, input costs and occurrence of resistant pests, all capable of altering the value of pest management tactics in an integrated pest management program. We provide a framework for calculating expected yield and expected net revenue of pest management scenarios, using the soybean aphid (Aphis glycines) as a case study. Foliar insecticide and host-plant resistance are effective management tactics for preventing yield loss from soybean aphid outbreaks; however, pyrethroid-resistant aphid populations pose a management challenge for farmers. We evaluated eight scenarios relevant to soybean aphid management in Iowa with varying probabilities of aphid outbreaks and insecticide-resistant aphids occurring. RESULTS Our equation suggests that insecticide use is profitable when the probability of an aphid outbreak is ≥29%, and soybean production will become more costly with increasing probability of pyrethroid-resistant aphids. If farmers continue to use pyrethroids, they will not experience financial consequences from pyrethroid-resistant aphids until the chance of insecticide resistance is 48%. Aphid-resistant varieties provided consistent yield and offered the highest net revenue under all conditions. CONCLUSION This framework can be used for other crop-pest systems to evaluate the profitability of management tactics and investigate how resistance impacts revenue for farmers. Including the cost of resistance in crop budgets can help farmers and agronomic consultants comprehend these impacts and enhance decision-making to increase revenue and curb resistance development.
Collapse
Affiliation(s)
- Ashley N Dean
- Department of EntomologyIowa State UniversityAmesIAUSA
| | - Jarad B Niemi
- Department of StatisticsIowa State UniversityAmesIAUSA
| | - John C Tyndall
- Department of Natural Resource Ecology and ManagementIowa State UniversityAmesIAUSA
| | | | | |
Collapse
|
7
|
Yates-Stewart AD, Pekarcik A, Michel A, Blakeslee JJ. Jasmonic Acid-Isoleucine (JA-Ile) Is Involved in the Host-Plant Resistance Mechanism Against the Soybean Aphid (Hemiptera: Aphididae). JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2972-2978. [PMID: 33033836 DOI: 10.1093/jee/toaa221] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Indexed: 06/11/2023]
Abstract
Host-plant resistance (HPR) is an important tool for pest management, affording both economic and environmental benefits. The mechanisms of aphid resistance in soybean are not well understood, but likely involve the induction of the jasmonic acid (JA) pathway, and possibly other phytohormone signals involved in plant defense responses. Despite the efficacy of aphid resistance in soybean, virulent aphids have overcome this resistance through mostly unknown mechanisms. Here, we have used metabolomic tools to define the role of plant phytohormones, especially the JA pathway, in regulating interactions between aphid-resistant soybean and virulent aphids. We hypothesized that virulent aphids avoid or suppress the JA pathway to overcome aphid resistance. Our results suggested that aphid-resistant soybean increased accumulation of JA-isoleucine (JA-Ile) only when infested with avirulent aphids; virulent aphids did not cause induction of JA-Ile. Further, applying JA-Ile to aphid-resistant soybean reduced subsequent virulent aphid populations. The concentrations of other phytohormones remained unchanged due to aphid feeding, highlighting the importance of JA-Ile in this interaction. These results increase our knowledge of soybean resistance mechanisms against soybean aphids and contribute to our understanding of aphid virulence mechanisms, which will in turn promote the durability of HPR.
Collapse
Affiliation(s)
- Ashley D Yates-Stewart
- Center for Applied Plant Sciences, The Ohio State University, CFAES Wooster Campus, Wooster, OH
| | - Adrian Pekarcik
- Department of Entomology, The Ohio State University, CFAES Wooster Campus, Wooster, OH
| | - Andy Michel
- Center for Applied Plant Sciences, The Ohio State University, CFAES Wooster Campus, Wooster, OH
- Department of Entomology, The Ohio State University, CFAES Wooster Campus, Wooster, OH
| | - Joshua J Blakeslee
- Center for Applied Plant Sciences, The Ohio State University, CFAES Wooster Campus, Wooster, OH
- Laboratory for the Analysis of Metabolites from Plants and Department of Horticulture and Crop Sciences, The Ohio State University, Wooster, OH
| |
Collapse
|
8
|
Coates BS, Hohenstein JD, Giordano R, Donthu RK, Michel AP, Hodgson EW, O'Neal ME. Genome scan detection of selective sweeps among biotypes of the soybean aphid, Aphis glycines, with differing virulence to resistance to A. glycines (Rag) traits in soybean, Glycine max. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 124:103364. [PMID: 32360957 DOI: 10.1016/j.ibmb.2020.103364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 11/22/2019] [Accepted: 03/18/2020] [Indexed: 05/12/2023]
Abstract
Multiple biotypes of soybean aphid, Aphis glycines, occur in North America adapted for survival (virulence) on soybean, Glycine max, with one or more different resistance to A. glycines (Rag) traits. The degree of genome-wide variance between biotypes and the basis of virulence remains unknown, but the latter is hypothesized to involve secreted effector proteins. Between 167,249 and 217,750 single nucleotide polymorphisms (SNPs) were predicted from whole genome re-sequencing of A. glycines avirulent biotype 1 (B1) and virulent B2, B3 and B4 colony-derived iso-female lines when compared to the draft B1 genome assembly, Ag_bt1_v6.0. Differences in nucleotide diversity indices (π) estimated within 1000 bp sliding windows demonstrated that 226 of 353 (64.0%) regions most differentiated between B1 and ≥ 2 virulent biotypes, representing < 0.1% of the 308 Mb assembled genome size, are located on 15 unordered scaffolds. Furthermore, these 226 intervals were coincident and show a significant association with 326 of 508 SNPs with significant locus-by-locus FST estimates between biotype populations (r = 0.6271; F1,70 = 45.36, P < 0.001) and genes showing evidence of directions selection (πN/πS > 2.0; r = 0.6233; F1,70 = 50.20, P < 0.001). A putative secreted effector glycoprotein is encoded in proximity to genome intervals of low estimated π (putative selective sweep) within avirulent B1 compared to all three virulent biotypes. Additionally, SNPs are clustered in or in proximity to genes putatively involved in intracellular protein cargo transport and the regulation of secretion. Results of this study indicate that factors on a small number of scaffolds of the A. glycines genome may contribute to variance in virulence towards Rag traits in G. max.
Collapse
Affiliation(s)
- Brad S Coates
- USDA-ARS, Corn Insects & Crop Genetics Research Unit, Ames, IA, 50011, USA.
| | | | - Rosanna Giordano
- Puerto Rico Science, Technology and Research Trust, San Juan, PR, 00927, USA; Know Your Bee Inc., San Juan, PR, 00927, USA
| | - Ravi Kiran Donthu
- Puerto Rico Science, Technology and Research Trust, San Juan, PR, 00927, USA; Know Your Bee Inc., San Juan, PR, 00927, USA
| | - Andrew P Michel
- The Ohio State University, Department of Entomology, and Center for Applied Plant Sciences Wooster, OH, 44691, USA
| | - Erin W Hodgson
- Iowa State University, Department of Entomology, Ames, IA, 50011, USA
| | - Matthew E O'Neal
- Iowa State University, Department of Entomology, Ames, IA, 50011, USA
| |
Collapse
|
9
|
Natukunda MI, MacIntosh GC. The Resistant Soybean- Aphis glycines Interaction: Current Knowledge and Prospects. FRONTIERS IN PLANT SCIENCE 2020; 11:1223. [PMID: 32849757 PMCID: PMC7431774 DOI: 10.3389/fpls.2020.01223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
Soybean aphids (Aphis glycines Matsumura) are invasive insect pests of soybean, and they cause significant yield losses. Resistance to soybean aphids is conferred by Resistance to Aphis glycines (Rag) genes. Since the first discovery of aphid-resistant soybean genotypes in 2004, several studies have attempted to characterize Rag genes from aphid-resistant soybean genotypes. To date, 12 Rag genes and four quantitative trait loci for aphid resistance have been reported on soybean chromosomes 07, 08, 13, 16, and 17. Although candidate genes have been proposed for several discovered Rag loci, additional studies are needed to pinpoint, validate, and further explain the potential mechanisms of Rag gene action. A major challenge to utilizing host plant resistance is the discovery of virulent aphid biotypes that can colonize aphid-resistant soybean. This occurrence suggests the need for additional studies to devise strategies to enhance the effectiveness of aphid-resistant soybean. In this mini review, we discuss current knowledge on the resistant soybean-Aphis glycines interaction, potential mechanisms of Rag gene action, opportunities to discover new Rag genes, and prospects for utilization of host plant resistance to manage soybean aphids. A clearer understanding of host plant resistance to soybean aphids will guide researchers on strategies for developing soybean varieties with more durable aphid resistance, reducing the present challenge of virulent aphid biotypes.
Collapse
Affiliation(s)
- Martha I. Natukunda
- MacIntosh Laboratory, Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
- Department of Agronomy, Iowa State University, Ames, IA, United States
| | - Gustavo C. MacIntosh
- MacIntosh Laboratory, Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
| |
Collapse
|
10
|
Yates-Stewart AD, Daron J, Wijeratne S, Shahid S, Edgington HA, Slotkin RK, Michel A. Soybean aphids adapted to host-plant resistance by down regulating putative effectors and up regulating transposable elements. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 121:103363. [PMID: 32201218 DOI: 10.1016/j.ibmb.2020.103363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 03/06/2020] [Accepted: 03/15/2020] [Indexed: 06/10/2023]
Abstract
In agricultural systems, crops equipped with host-plant resistance (HPR) have enhanced protection against pests, and are used as a safe and sustainable tool in pest management. In soybean, HPR can control the soybean aphid (Aphis glycines), but certain aphid populations have overcome this resistance (i.e., virulence). The molecular mechanisms underlying aphid virulence to HPR are unknown, but likely involve effector proteins that are secreted by aphids to modulate plant defenses. Another mechanism to facilitate adaptation is through the activity of transposable elements, which can become activated by stress. In this study, we performed RNA sequencing of virulent and avirulent soybean aphids fed susceptible or resistant (Rag1 + Rag2) soybean. Our goal was to better understand the molecular mechanisms underlying soybean aphid virulence. Our data showed that virulent aphids mostly down regulate putative effector genes relative to avirulent aphids, especially when aphids were fed susceptible soybean. Decreased expression of effectors may help evade HPR plant defenses. Virulent aphids also transcriptionally up regulate a diverse set of transposable elements and nearby genes, which is consistent with stress adaptation. Our work demonstrates two mechanisms of pest adaptation to resistance, and identifies effector gene targets for future functional testing.
Collapse
Affiliation(s)
| | - Josquin Daron
- CNRS, Centre National de la Recherche Scientifique, Montpellier, France
| | - Saranga Wijeratne
- The Ohio State University, Molecular and Cellular Imaging Center, OARDC, Wooster, OH, USA
| | - Saima Shahid
- Donald Danforth Plant Science Center, St, Louis, MO, USA
| | - Hilary A Edgington
- The Ohio State University, Department of Entomology, CFAES Wooster Campus, Wooster, OH, USA
| | - R Keith Slotkin
- Donald Danforth Plant Science Center, St, Louis, MO, USA; Division of Biological Sciences, University of Missouri, Columbia, MO, USA
| | - Andy Michel
- The Ohio State University, Center for Applied Plant Sciences, Wooster, OH, USA; The Ohio State University, Department of Entomology, CFAES Wooster Campus, Wooster, OH, USA.
| |
Collapse
|
11
|
Neupane S, Purintun JM, Mathew FM, Varenhorst AJ, Nepal MP. Molecular Basis of Soybean Resistance to Soybean Aphids and Soybean Cyst Nematodes. PLANTS 2019; 8:plants8100374. [PMID: 31561499 PMCID: PMC6843664 DOI: 10.3390/plants8100374] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/05/2019] [Accepted: 09/17/2019] [Indexed: 01/25/2023]
Abstract
Soybean aphid (SBA; Aphis glycines Matsumura) and soybean cyst nematode (SCN; Heterodera glycines Ichninohe) are major pests of the soybean (Glycine max [L.] Merr.). Substantial progress has been made in identifying the genetic basis of limiting these pests in both model and non-model plant systems. Classical linkage mapping and genome-wide association studies (GWAS) have identified major and minor quantitative trait loci (QTLs) in soybean. Studies on interactions of SBA and SCN effectors with host proteins have identified molecular cues in various signaling pathways, including those involved in plant disease resistance and phytohormone regulations. In this paper, we review the molecular basis of soybean resistance to SBA and SCN, and we provide a synthesis of recent studies of soybean QTLs/genes that could mitigate the effects of virulent SBA and SCN populations. We also review relevant studies of aphid–nematode interactions, particularly in the soybean–SBA–SCN system.
Collapse
Affiliation(s)
- Surendra Neupane
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
| | - Jordan M Purintun
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
| | - Febina M Mathew
- Department of Agronomy, Horticulture and Plant Science, South Dakota State University, Brookings, SD 57007, USA.
| | - Adam J Varenhorst
- Department of Agronomy, Horticulture and Plant Science, South Dakota State University, Brookings, SD 57007, USA.
| | - Madhav P Nepal
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
| |
Collapse
|
12
|
Conzemius SR, Hesler LS, Varenhorst AJ, Tilmon KJ. Resistance of Soybean Plant Introductions to Three Colonies of Soybean Aphid (Hemiptera: Aphididae) Biotype 4. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:2407-2417. [PMID: 31081894 DOI: 10.1093/jee/toz116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Indexed: 05/12/2023]
Abstract
Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), infestations of soybean, Glycine max (L.) Merr. (Fabales: Fabaceae), and the associated yield loss have led to a large dependence on insecticidal management in soybean throughout the Midwestern United States. However, several populations of pyrethroid-resistant soybean aphids have recently been found in Iowa, Minnesota, North Dakota and South Dakota, which highlights the importance of alternative management approaches. One such alternative method is host-plant resistance, which uses naturally occurring plant defenses in crop cultivars to reduce the potential for yield loss from a pest population. Current soybean aphid-resistant cultivars do not protect against all soybean aphids due to the presence of virulent biotypes. In particular, soybean aphid biotype 4 is virulent to Rag1 and Rag2 resistance genes both individually and in combination. However, we hypothesized that resistance to biotype 4 may exist in previously identified, but uncharacterized resistant soybean plant introductions (PIs). To test this, we evaluated 51 previously identified but uncharacterized soybean aphid-resistant PIs for their resistance to colonies of soybean aphid biotype 4 collected in separate site-years (Lomira, WI 2013; Volga, SD 2015, 2016). Free-choice tests identified 14 PIs with putative resistance to 'Lomira13', two to 'Volga15', and eight to 'Volga16' soybean aphid colonies. Follow-up, no-choice tests corroborated two to three resistant PIs per colony, and PI 437696, which was resistant to each of the three colonies and could aid in breeding efforts and an integrated approach to soybean aphid management.
Collapse
Affiliation(s)
- Sophia R Conzemius
- Agronomy, Horticulture, and Plant Science Department, South Dakota State University, SAG, Brookings, SD
| | - Louis S Hesler
- North Central Agricultural Research Laboratory, Agricultural Research Service, USDA, Brookings, SD
| | - Adam J Varenhorst
- Agronomy, Horticulture, and Plant Science Department, South Dakota State University, SAG, Brookings, SD
| | - Kelley J Tilmon
- Agronomy, Horticulture, and Plant Science Department, South Dakota State University, SAG, Brookings, SD
| |
Collapse
|
13
|
Esquivel CJ, Ranger CM, Phelan PL, Martinez EJ, Hendrix WH, Canas LA, Michel AP. Weekly Survivorship Curves of Soybean Aphid Biotypes 1 and 4 on Insecticidal Seed-Treated Soybean. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:712-719. [PMID: 30715412 DOI: 10.1093/jee/toy410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Indexed: 06/09/2023]
Abstract
Thiamethoxam, an insecticide used in soybean seed treatments, effectively suppresses soybean aphids (Aphis glycines) Matsumura (Hemiptera: Aphididae) for a short time after planting. However, exactly when and how quickly soybean aphid populations could increase is unknown. Likewise, we lack data on virulent soybean aphid biotypes (that can overcome soybean resistance) when fed on seed-treated soybean. Determining the survival of soybean aphids over time on insecticidal seed-treated soybean is critical for improving soybean aphid management and may provide insights to manage aphid virulence to aphid resistant-soybean. In greenhouse and field experiments, aphid-susceptible soybean plants (with and without an insecticidal seed treatment) were infested at 7, 14, 21, 28, 35, and 42 days after planting (DAP). We compared aphid survival among biotypes 1 (avirulent) and 4 (virulent) and insecticide treatment 72 h after infestation. We also measured thiamethoxam concentrations in plant tissue using liquid chromatography-tandem mass spectrometry. As expected, soybean aphid survival was significantly lower on seed-treated soybean up to 35 DAP for both biotypes, which correlates with the decrease of thiamethoxam in the plant over time. Moreover, we found no significant difference between avirulent and virulent biotype survivorship on insecticidal seed-treated soybean plants, although we did find significantly greater survival for the virulent biotype compared with the avirulent biotype on untreated soybean in the field. In conclusion, our study further characterized the relative short duration of seed treatment effectiveness on soybean aphid and showed that survivorship of virulent aphids on seed-treated soybean is similar to avirulent aphids.
Collapse
Affiliation(s)
- Carlos J Esquivel
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH
| | - Christopher M Ranger
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH
- Horticultural Insects Research Lab, USDA-Agricultural Research Service, Wooster, OH
| | - P Larry Phelan
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH
| | - Erick J Martinez
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH
| | | | - Luis A Canas
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH
| | - Andrew P Michel
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH
- Center of Applied Plant Sciences, The Ohio State University, Wooster, OH
| |
Collapse
|
14
|
Marchi-Werle L, Fischer HD, Graef G, Hunt TE, Heng-Moss TM. Characterization and Identification of Methods for Phenotyping Soybean Populations With Tolerance to the Soybean Aphid (Hemiptera: Aphididae). JOURNAL OF ECONOMIC ENTOMOLOGY 2018; 111:2416-2425. [PMID: 29982624 DOI: 10.1093/jee/toy177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Indexed: 06/08/2023]
Abstract
The development of soybeans tolerant to the soybean aphid [Aphis glycines Matsumura (Hemiptera: Aphididae)] remains unexplored. The objectives of this research were to determine the susceptibility of two high-yielding soybean [Glycine max (L.) Merrill (Fabales: Fabaceae)] genotypes involved in a breeding platform to develop aphid-tolerant recombinant inbred lines (RILs); characterize the peroxidase activity and relative expression of peroxidase transcripts in the parents of RILs; and identify an assay to phenotype aphid-tolerant RILs. Enzyme kinetic assays documented the total peroxidase activity for tolerant (KS4202), susceptible (SD76R), and two high-yielding (U09-105007 and U11-611112) soybeans during two vegetative stages (V1 and V3) at three sampling days (D4, D6, and D8 after aphid introduction). Enzyme kinetic assays showed that V3 infested tolerant and U11-611112 plants had significantly higher peroxidase activity than their respective control plants at D4, and infested tolerant plants were also higher than control plants at D6. There were no apparent trends when comparing the expression of peroxidase-specific transcripts in the absence of aphids (basal levels) in both V1 and V3. Relative expression analyses of two peroxidase transcripts (PRX52 and PRX2) performed to compare differences among the soybean genotypes indicated that, despite basal levels being similar for the treatments analyzed, tolerant soybeans had a tendency for a higher expression of PRX52 in the presence of aphids. Based on the different patterns observed and the feasibility of analyses performed in this study, enzyme kinetics using V3 infested plants may be a marker for screening RILs in a breeding program targeting the development of aphid-tolerant soybeans.
Collapse
Affiliation(s)
- L Marchi-Werle
- Department of Entomology, University of Nebraska - Lincoln, Lincoln, NE
| | - H D Fischer
- Department of Entomology, University of Arkansas, Fayetteville, AR
| | - G Graef
- Department of Agronomy and Horticulture, University of Nebraska - Lincoln, Lincoln, NE
| | - T E Hunt
- Department of Entomology, Haskell Agricultural Laboratory, University of Nebraska - Lincoln, Concord, NE
| | - T M Heng-Moss
- Department of Entomology, University of Nebraska - Lincoln, Lincoln, NE
| |
Collapse
|
15
|
Abstract
Insect pests are responsible for substantial crop losses worldwide through direct damage and transmission of plant diseases, and novel approaches that complement or replace broad-spectrum chemical insecticides will facilitate the sustainable intensification of food production in the coming decades. Multiple strategies for improved crop resistance to insect pests, especially strategies relating to plant secondary metabolism and immunity and microbiome science, are becoming available. Recent advances in metabolic engineering of plant secondary chemistry offer the promise of specific toxicity or deterrence to insect pests; improved understanding of plant immunity against insects provides routes to optimize plant defenses against insects; and the microbiomes of insect pests can be exploited, either as a target or as a vehicle for delivery of insecticidal agents. Implementation of these advances will be facilitated by ongoing advances in plant breeding and genetic technologies.
Collapse
Affiliation(s)
- Angela E Douglas
- Department of Entomology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA;
| |
Collapse
|
16
|
O'Neal ME, Varenhorst AJ, Kaiser MC. Rapid evolution to host plant resistance by an invasive herbivore: soybean aphid (Aphis glycines) virulence in North America to aphid resistant cultivars. CURRENT OPINION IN INSECT SCIENCE 2018; 26:1-7. [PMID: 29764648 DOI: 10.1016/j.cois.2017.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 12/31/2017] [Indexed: 06/08/2023]
Abstract
Preventing rapid evolution of herbivores to plant traits that confer resistance is an area of active research for applied entomologists. The subfield of insect resistance management (IRM) uses elements of population genetics and ecology to prevent increases in the frequency of virulent (i.e. resistant) sub-populations of an insect pest. Efforts to delay such an increase include using highly lethal toxins (i.e., a high dose), combining multiple resistance traits in one cultivar (i.e., pyramids), and using susceptible plants (i.e. a refuge) within or near plantings of the resistant crop. Even if fully implemented, theoretical models suggest that IRM plans for asexually-reproducing insects (e.g. aphids) cannot limit the frequency of resistance to provide sustainable use of a pest-resistant cultivar. We discuss how feeding by conspecifics aphids induces susceptibility such that a "within plant" refuge is created, allowing both virulent and avirulent (i.e. susceptible) populations to persist. We use the soybean aphid (Aphis glycines Matsumura), and the rapid occurrence of virulence in the US to resistant cultivars of soybean (Glycine max). We describe how feeding by A. glycines on soybeans alters the quality of the plant as a host. These systemic changes to the plants' physiology allow avirulent A. glycines to thrive on resistant cultivars. We explore how the induction of susceptibility by a herbivore can slow an increase in the frequency of virulent populations to resistant host plants. We suggest that a within plant refuge, combined with standard IRM practices, can allow for sustainable use of plant resistance to asexually-reproducing insect pests.
Collapse
Affiliation(s)
| | - Adam J Varenhorst
- Department of Agronomy, Horticulture and Plant Science, South Dakota State University, Brookings, SD, USA
| | | |
Collapse
|
17
|
Varenhorst AJ, Pritchard SR, O'Neal ME, Hodgson EW, Singh AK. Determining the Effectiveness of Three-Gene Pyramids Against Aphis glycines (Hemiptera: Aphididae) Biotypes. JOURNAL OF ECONOMIC ENTOMOLOGY 2017; 110:2428-2435. [PMID: 29220517 DOI: 10.1093/jee/tox230] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Since the discovery of Aphis glycines Matsumura (Hemiptera: Aphididae) in the United States, the primary management tactic has been foliar insecticides. Alternative management options such as host plant resistance to A. glycines have been developed and their effectiveness proved. However, the use of host plant resistance was complicated by the discovery of multiple, virulent biotypes of A. glycines in the United States that are capable of overcoming single Rag genes, Rag1 and Rag2, as well as a two-gene pyramid of Rag1+Rag2. However, current models predict that the virulent allele frequency of A. glycines decreases in response to the use of pyramided Rag genes, suggesting that pyramids represent a more sustainable use of these traits. Previous research has demonstrated that virulent biotypes can be effectively managed using a three-gene pyramid of Rag1+Rag2+Rag3. Additional Rag-genes have been discovered (Rag4 and Rag5), but whether the incorporation of these genes into novel three-gene pyramids will improve efficacy is not known. We tested single-gene (Rag1 and Rag2) and pyramid cultivars (Rag1+Rag2, Rag1+Rag2+Rag3, Rag1+Rag2+Rag4) to multiple biotypes in laboratory assays. Our results confirm that the Rag1+Rag2+Rag3 pyramid effectively manages all known A. glycines biotypes when compared with cultivars that are overcome by the associated biotype. Our results indicate that Rag1+Rag2+Rag4 would be an effective management option for biotype-1, biotype-2, and biotype-3 A. glycines, but had a negligible impact on biotype-4.
Collapse
Affiliation(s)
| | | | - M E O'Neal
- Department of Entomology, Iowa State University
| | - E W Hodgson
- Department of Entomology, Iowa State University
| | - A K Singh
- Agronomy Department, Iowa State University
| |
Collapse
|
18
|
Alves TM, Marston ZP, MacRae IV, Koch RL. Effects of Foliar Insecticides on Leaf-Level Spectral Reflectance of Soybean. JOURNAL OF ECONOMIC ENTOMOLOGY 2017; 110:2436-2442. [PMID: 29029168 DOI: 10.1093/jee/tox250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Indexed: 06/07/2023]
Abstract
Pest-induced changes in plant reflectance are crucial for the development of pest management programs using remote sensing. However, it is unknown if plant reflectance data is also affected by foliar insecticides applied for pest management. Our study assessed the effects of foliar insecticides on leaf reflectance of soybean. A 2-yr field trial and a greenhouse trial were conducted using randomized complete block and completely randomized designs, respectively. Treatments consisted of an untreated check, a new systemic insecticide (sulfoxaflor), and two representatives of the most common insecticide classes used for soybean pest management in the north-central United States (i.e., λ-cyhalothrin and chlorpyrifos). Insecticides were applied at labeled rates recommended for controlling soybean aphid; the primary insect pest in the north-central United States. Leaf-level reflectance was measured using ground-based spectroradiometers. Sulfoxaflor affected leaf reflectance at some red and blue wavelengths but had no effect at near-infrared or green wavelengths. Chlorpyrifos affected leaf reflectance at some green, red, and near-infrared wavelengths but had no effect at blue wavelengths. λ-cyhalothrin had the least effect on spectral reflectance among the insecticides, with changes to only a few near-infrared wavelengths. Our results showing immediate and delayed effects of foliar insecticides on soybean reflectance indicate that application of some insecticides may confound the use of remote sensing for detection of not only insects but also plant diseases, nutritional and water deficiencies, and other crop stressors.
Collapse
Affiliation(s)
| | | | - Ian V MacRae
- Department of Entomology, University of Minnesota
| | | |
Collapse
|
19
|
Marchi-Werle L, Baldin ELL, Fischer HD, Heng-Moss TM, Hunt TE. Economic Injury Levels for Aphis glycines Matsumura (Hemiptera: Aphididae) on the Soybean Aphid Tolerant KS4202 Soybean. JOURNAL OF ECONOMIC ENTOMOLOGY 2017; 110:2100-2108. [PMID: 28961855 DOI: 10.1093/jee/tox225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Indexed: 06/07/2023]
Abstract
The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an invasive species from Asia that has been the major economic insect pest of soybeans, Glycine max (L.) Merrill, since 2000. While use of soybeans expressing antibiosis and antixenosis is a well-studied strategy to manage this pest, aphid-tolerant soybeans remain underexplored. This study examined the relationship between cumulative aphid-days (CAD) and yield loss in the tolerant soybean KS4202 during two growing seasons to determine the economic injury levels (EILs) for soybean aphids on KS4202. Soybean aphid infestations were initiated during the soybean reproductive stages. A range of CAD treatments (3,000-45,000 CADs) were applied during the growing seasons. Aphid populations reached 45,000 CAD in 2011 and 38,000 CAD in 2013 in plots that were not treated with insecticides. It was estimated that the population doubling time was 9.4 d. In infested plots, soybean yield was reduced by 1.4-13.3%, equivalent to a 3.1% yield loss for every 10,000 CAD. Overall, most CAD treatments did not affect yield parameters, although CAD > 39,000 caused a significant reduction in most yield parameters. The EILs calculated for KS4202 ranged from 526 to 2,050 aphids/plant, which were approximately 2.5-fold higher when compared to EILs previously calculated for susceptible soybean. The adoption of soybean aphid tolerant soybean with higher EILs may help mitigate treatment delay problems by lengthening the treatment lead-time and possibly reduce the number of insecticide applications.
Collapse
Affiliation(s)
- Lia Marchi-Werle
- Department of Entomology, University of Nebraska-Lincoln, 103 Entomology Hall, Lincoln, NE 68583
| | - Edson L L Baldin
- Department of Crop Protection, Sao Paulo State University (UNESP), Botucatu, SP 18610, Brazil
| | - Hillary D Fischer
- Department of Entomology, University of Arkansas, 319 Agriculture Building, Fayetteville, AR 72701
| | - Tiffany M Heng-Moss
- College of Agricultural Sciences & Natural Resources, University of Nebraska-Lincoln, 103 Agricultural Hall, Lincoln, NE 68583
| | - Thomas E Hunt
- Department of Entomology, NEREC Haskell Agricultural Laboratory, University of Nebraska-Lincoln, 57905 866 Road, Concord, NE 68728
| |
Collapse
|
20
|
Varenhorst AJ, O’Neal ME. The Effect of an Interspersed Refuge on Aphis glycines (Hemiptera: Aphididae), Their Natural Enemies, and Biological Control. JOURNAL OF ECONOMIC ENTOMOLOGY 2016; 109:406-15. [PMID: 26476557 PMCID: PMC4765486 DOI: 10.1093/jee/tov302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 09/30/2015] [Indexed: 06/05/2023]
Abstract
Soybean production in the north central United States has relied heavily on the use of foliar and seed applied insecticides to manage Aphis glycines (Hemiptera: Aphididae). An additional management strategy is the use soybean cultivars containing A. glycines resistance genes (Rag). Previous research has demonstrated that Rag cultivars are capable of preventing yield loss equivalent to the use of foliar and seed-applied insecticides.However, the presence of virulent biotypes in North America has raised concern for the durability of Rag genes. A resistance management program that includes a refuge for avirulent biotypes could limit the frequency at which virulent biotypes increase within North America. To what extent such a refuge reduces the effectiveness of aphid-resistant soybean is not clear. We conducted an experiment to determine whether a susceptible refuge mixed into resistant soybean (i.e., interspersed refuge or refuge-in-a-bag) affects the seasonal exposure of aphids, their natural enemies, biological control, and yield protection provided by aphid resistance. We compared three ratios of interspersed refuges (resistant: susceptible; 95:5, 90:10, 75:25) to plots grown with 100%susceptible or resistant soybean. We determined that an interspersed refuge of at least 25% susceptible seed would be necessary to effectively produce avirulent individuals. Interspersed refuges had negligible effects onyield and the natural enemy community. However, there was evidence that they increased the amount of biological control that occurred within a plot. We discuss the compatibility of interspersed refuges for A. glycines management and whether resistance management can prolong the durability of Rag genes.
Collapse
Affiliation(s)
- A. J. Varenhorst
- Department of Entomology, Iowa State University, Ames, IA 50011 () and
| | - M. E. O’Neal
- Department of Entomology, Iowa State University, Ames, IA 50011 () and
| |
Collapse
|