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Codod C, Severns P, Sparks AN, Srinivasan R, Kemerait R, Dutta B. Assessment of prickly sida as a potential inoculum source for sida golden mosaic virus in commercial snap bean farms in Georgia, United States. Plant Dis 2024. [PMID: 38243178 DOI: 10.1094/pdis-09-23-1901-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2024]
Abstract
Sida golden mosaic virus (SiGMV), an obligate pathogen that infects snap beans (Phaseolus vulgaris), is known to infect prickly sida (Sida spinosa L.), which is a common weed in agricultural farms in Georgia. Prickly sida has also been reported as a suitable host of sweetpotato whitefly (Bemisia tabaci), the vector of SiGMV. Despite being a host for both SiGMV and its vector, the role of prickly sida as a reservoir and inoculum source for SiGMV in snap bean farms has not been evaluated. This study was conducted to document the occurrence of SiGMV-infected prickly sida plants and to assess its potential role as a source of SiGMV inoculum in snap bean farms. A survey of 17 commercial snap bean farms conducted in spring 2021 confirmed the presence of SiGMV-infected prickly sida in southern Georgia. In fall 2021 and 2022, on-farm field trials were conducted in four commercial farms where SiGMV-infected prickly sida plants were documented earlier as a part of survey in spring 2021. The spatial distribution and temporal patterns of adult whiteflies and SiGMV on snap bean were compared between macroplots (13.7 m x 30.5 m), 'with prickly sida' or 'without prickly sida', that were at least 232 m apart from each other. We did not observe any consistent differences in counts of adult whiteflies between macroplots with or without prickly sida in the four commercial farms. SiGMV infection was detected earlier and with higher incidences in snap bean macroplots 'with prickly sida' compared with macroplots 'without prickly sida'. An apparent disease gradient was observed in two of the four farms assessed. Higher SiGMV incidences were observed on the edges of macroplots 'with prickly sida'. These findings indicate prickly sida as a potential natural reservoir and a source for SiGMV spread in snap bean farms in southern Georgia.
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Affiliation(s)
- Clarence Codod
- University of Georgia, 1355, Plant Pathology, 2604 Research Way, Horticulture Bldg, UGA, Tifton, GA 31794, Tifton, Georgia, United States, 31794;
| | - Paul Severns
- University of Georgia, 1355, Plant Pathology, 2315 Miller Plant Sciences, Athens, Georgia, United States, 30602-0002;
| | - Alton N Sparks
- University of Georgia, Georgia Cooperative Extension Service, Tifton, Georgia, United States;
| | - Rajagopalbabu Srinivasan
- University of Georgia, Entomology, 1109 Experiment street, Griffin, Georgia, United States, 30223;
| | - Robert Kemerait
- University of Georgia, Plant Pathology, 4604 Research Way, PO Box 748, Tifton, Georgia, United States, 31794;
| | - Bhabesh Dutta
- University of Georgia, Plant Pathology, 2360 Rainwater Road, Tifton, Georgia, United States, 31793
- University of Georgia, Plant Pathology, 2360 Rainwater Road, Tifton, Georgia, United States, 31793;
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Wu S, Toews MD, Behle RW, Barman AK, Sparks AN, Simmons AM, Shapiro-Ilan DI. Post-Application Field Persistence and Efficacy of Cordyceps javanica against Bemisia tabaci. J Fungi (Basel) 2023; 9:827. [PMID: 37623598 PMCID: PMC10455680 DOI: 10.3390/jof9080827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 07/28/2023] [Accepted: 08/01/2023] [Indexed: 08/26/2023] Open
Abstract
Previously, Cordyceps javanica Wf GA17, a causing agent of whitefly epizootics in southern Georgia, demonstrated superior temperature tolerance and higher virulence against the whitefly Bemisia tabaci than commercial strains in the laboratory. The post-application persistence and efficacy of this fungus against B. tabaci were compared with that of the commercially available C. javanica Apopka97 strain over a two-year field study in cotton and vegetable crops. When blastospores of both strains were applied alone, whitefly populations were not effectively suppressed. Thus, JMS stylet oil was added to fungal treatments for enhancing efficacy and persistence. For 0-day samples, all fungal treatments caused similar but significant levels of immature mortality regardless of fungal strain, propagule form (conidia vs. blastospores), and application method (alone or mixed with JMS). In follow-up samplings, Wf GA17 blastospores + JMS achieved higher control levels than other treatments in some trials, but the efficacy did not last long. The JMS oil alone caused significant mortality and suppressed whiteflies. Over 90% of spores lost viability 24 h after treatment in all fungal treatments. Across evaluation times, there was no difference between the two fungal strains (conidia or blastospores, alone or combined with JMS), but conidia persisted better than blastospores for both strains. Overall, the field persistence and efficacy of C. javanica did not last long; therefore, improved delivery methods and formulations are needed for enhancement.
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Affiliation(s)
- Shaohui Wu
- Department of Entomology, University of Georgia, 2360 Rainwater Road, Tifton, GA 31793, USA; (S.W.); (A.K.B.); (A.N.S.)
| | - Michael D. Toews
- Department of Entomology, University of Georgia, 2360 Rainwater Road, Tifton, GA 31793, USA; (S.W.); (A.K.B.); (A.N.S.)
| | - Robert W. Behle
- National Center for Agricultural Utilization Research, USDA-ARS, 1815 N. University St., Peoria, IL 61604, USA;
| | - Apurba K. Barman
- Department of Entomology, University of Georgia, 2360 Rainwater Road, Tifton, GA 31793, USA; (S.W.); (A.K.B.); (A.N.S.)
| | - Alton N. Sparks
- Department of Entomology, University of Georgia, 2360 Rainwater Road, Tifton, GA 31793, USA; (S.W.); (A.K.B.); (A.N.S.)
| | - Alvin M. Simmons
- U.S. Vegetable Laboratory, USDA-ARS, 2700 Savannah Highway, Charleston, SC 29414, USA;
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Kavalappara SR, Milner H, Konakalla NC, Morgan K, Sparks AN, McGregor C, Culbreath AK, Wintermantel WM, Bag S. High Throughput Sequencing-Aided Survey Reveals Widespread Mixed Infections of Whitefly-Transmitted Viruses in Cucurbits in Georgia, USA. Viruses 2021; 13:v13060988. [PMID: 34073397 PMCID: PMC8230054 DOI: 10.3390/v13060988] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/18/2021] [Accepted: 05/24/2021] [Indexed: 01/08/2023] Open
Abstract
Viruses transmitted by the sweet potato whitefly (Bemisia tabaci) have been detrimental to the sustainable production of cucurbits in the southeastern USA. Surveys were conducted in the fall of 2019 and 2020 in Georgia, a major cucurbit-producing state of the USA, to identify the viruses infecting cucurbits and their distribution. Symptomatic samples were collected and small RNA libraries were prepared and sequenced from three cantaloupes, four cucumbers, and two yellow squash samples. An analysis of the sequences revealed the presence of the criniviruses cucurbit chlorotic yellows virus (CCYV), cucurbit yellow stunting disorder virus (CYSDV), and the begomovirus cucurbit leaf crumple virus (CuLCrV). CuLCrV was detected in 76%, CCYV in 60%, and CYSDV in 43% of the total samples (n = 820) tested. The level of mixed infections was high in all the cucurbits, with most plants tested being infected with at least two of these viruses. Near-complete genome sequences of two criniviruses, CCYV and CYSDV, were assembled from the small RNA sequences. An analysis of the coding regions showed low genetic variability among isolates from different hosts. In phylogenetic analysis, the CCYV isolates from Georgia clustered with Asian isolates, while CYSDV isolates clustered with European and USA isolates. This work enhances our understanding of the distribution of viruses on cucurbits in South Georgia and will be useful to develop strategies for managing the complex of whitefly-transmitted viruses in the region.
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Affiliation(s)
- Saritha Raman Kavalappara
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA; (S.R.K.); (H.M.); (N.C.K.); (K.M.); (A.K.C.)
| | - Hayley Milner
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA; (S.R.K.); (H.M.); (N.C.K.); (K.M.); (A.K.C.)
| | - Naga Charan Konakalla
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA; (S.R.K.); (H.M.); (N.C.K.); (K.M.); (A.K.C.)
| | - Kaelyn Morgan
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA; (S.R.K.); (H.M.); (N.C.K.); (K.M.); (A.K.C.)
| | - Alton N. Sparks
- Department of Entomology, University of Georgia, Tifton, GA 31793, USA;
| | - Cecilia McGregor
- Department of Horticulture, University of Georgia, Athens, GA 30602, USA;
| | - Albert K. Culbreath
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA; (S.R.K.); (H.M.); (N.C.K.); (K.M.); (A.K.C.)
| | - William M. Wintermantel
- United States Department of Agriculture-Agricultural Research Service, Salinas, CA 93905, USA
- Correspondence: (W.M.W.); (S.B.)
| | - Sudeep Bag
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA; (S.R.K.); (H.M.); (N.C.K.); (K.M.); (A.K.C.)
- Correspondence: (W.M.W.); (S.B.)
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Kavalappara SR, Milner H, Sparks AN, McGregor C, Wintermantel WM, Bag S. First report of cucurbit chlorotic yellows virus in association with other whitefly-transmitted viruses in squash (Cucurbita pepo) in Georgia. Plant Dis 2021; 105:1862. [PMID: 33417496 DOI: 10.1094/pdis-11-20-2429-pdn] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Viruses transmitted by whiteflies (Bemisia tabaci) cause severe damage to cucurbits in the southern United States. In the fall of 2020, samples of squash plants (Cucurbita pepo) exhibiting symptoms of yellow mottle, interveinal yellowing, and leaf crumple were collected from an insecticide trial in Tifton, Georgia. Total nucleic acid was isolated using the MagMAX 96 Viral RNA Isolation Kit (ThermoFisher Scientific) following the manufacturer's instructions but without DNase treatment. Polymerase chain reaction (PCR) and reverse transcription (RT)-PCR were carried out to determine the presence of whitefly-transmitted viruses. We identified infection by cucurbit chlorotic yellows virus (CCYV) using primers targeting a 953 nt segment of CCYV RNA1 encoding the RNA dependent RNA polymerase gene (RdRp) (CCYV-RDRP-1515F-5'CTCCGAGTAGATCATCCCAAATC3' and CCYV-RDRP-1515R-5'TCACCAGAAACTCCACAATCTC 3') along with other whitefly-transmitted viruses previously reported in Georgia. CCYV was detected from 27 of the 28 samples tested, while cucurbit yellow stunting disorder virus (CYSDV; Polston et al., 2008) and cucurbit leaf crumple virus (CuLCrV; Gadhave et al., 2020) were detected from 23 and 28 squash samples, respectively, with all three viruses regularly occurring as mixed infections. The presence of CCYV was further confirmed by amplification of portions of two different genomic segments from RNA2, including a section of the heat-shock protein (HSP) homolog gene (Bananej et al. 2013) as well as a portion of the coat protein (CP) gene which was amplified using primers CCYV_CPF-5'TCCCGGTGCCAACT GAGACA3' and CCYV_CPR- 5' TACGCGCGGCAGAGGAATTT 3'. The respective 462 bp HSP and 375 bp CP amplicons were cloned and sequenced. The partial coat protein gene sequence (MW251342) was 97.86% identical to a CCYV isolate from Shanghai (KY400633). The partial HSP sequence (MW251341) shared 99.73% identity with the recently identified CCYV isolate from California (MH806868). Criniviruses are an emerging group of whitefly-transmitted viruses responsible for worldwide losses of billions of dollars annually (Tzanetakis et al., 2013). CCYV, a member of the genus Crinivirus, was believed to be restricted to Asia, Africa, and the Mediterranean regions of Europe (Bananej et al., 2013; Orfanidou et al., 2014) until it was recently identified in the Imperial Valley of California (Wintermantel et al., 2019). Southern Georgia has been experiencing high whitefly populations, resulting in the emergence of CuLCrV and CYSDV on vegetables in recent years. Because CCYV can produce symptoms virtually identical to those of CYSDV and occurs in mixed infections in cucurbits with other whitefly-transmitted viruses, its epidemiology, role in disease incidence, severity, and impact on economically important crops in the southeastern United States will require further investigation.
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Affiliation(s)
- Saritha Raman Kavalappara
- University of Georgia College of Agricultural and Environmental Sciences, 96665, Department of Plant Pathology, Tifton, Georgia, United States;
| | - Hayley Milner
- University of Georgia College of Agricultural and Environmental Sciences, 96665, Department of Plant Pathology, Tifton, Georgia, United States;
| | - Alton N Sparks
- University of Georgia, Georgia Cooperative Extension Service, Tifton, Georgia, United States;
| | - Cecilia McGregor
- Horticulture, 1111 Miller Plant Sciences, Athens, Georgia, United States, 30602;
| | - William M Wintermantel
- USDA-ARS, Virology, 1636 East Alisal Street, Salinas, California, United States, 93905-3018
- United States;
| | - Sudeep Bag
- The University of Georgia, Department of Plant Pathology, 2360 Rainwater Rd, Tifton, Georgia, United States, 31793;
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Riley DG, Barwick S, Sparks AN, Harty T, Hamadi N. Reproductive Biology and Evidence of Diapause in the Cowpea Curculio (Coleoptera: Curculionidae). J Econ Entomol 2020; 113:882-886. [PMID: 31889179 DOI: 10.1093/jee/toz349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Indexed: 06/10/2023]
Abstract
Chalcodermus aeneus Boheman (Coleoptera: Curculionidae) has been the most destructive insect pest of black-eyed peas or cowpeas, Vigna unguiculata L. (Fabales: Fabaceae), over the last century in the southeastern United States. The historical distribution of this semitropical pest suggests the likelihood that diapause plays a key role in the overwintering success in parts of the United States. However, this report is the first to document biological evidence for diapause in C. aeneus. Our study assessed larval emergence from cowpea pods in the summer to fall growing seasons, egg development in female adults over the first (summer) and second (fall) generations, and adult emergence from infested soil after the first and second generations. There was a clear reduction in larval emergence from summer to fall. Egg and follicle development in female C. aeneus dropped off dramatically by September of each year. There was an extended emergence pattern of weevil adults from the soil in the fall as compared to the summer generation. Any future regional management of cowpea curculio will have to take into account the ability of this insect to diapause, thereby increasing its capacity to overwinter in regions where the cowpea crop, a warm-season, semitropical plant, is terminated with winter freezing temperatures.
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Affiliation(s)
- David G Riley
- Department of Entomology, University of Georgia Tifton Campus, Tifton, GA
| | - Sydni Barwick
- University of Georgia, Thomas County Extension, Thomasville, GA
| | - Alton N Sparks
- Department of Entomology, University of Georgia Tifton Campus, Tifton, GA
| | - Thomas Harty
- Office of Pesticide Programs, U.S. Environmental Protection Agency, NW. Washington, DC
| | - Negin Hamadi
- CAES Campus, Department of Plant Pathology, Tifton, GA
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Sparks AN, Gadal L, Ni X. Efficacy of Silk Channel Injections with Insecticides for Management of Lepidoptera Pests of Sweet Corn. J Econ Entomol 2015; 108:1869-1874. [PMID: 26470329 DOI: 10.1093/jee/tov113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 04/15/2015] [Indexed: 06/05/2023]
Abstract
The primary Lepidoptera pests of sweet corn (Zea mays L. convar. saccharata) in Georgia are the corn earworm, Helicoverpa zea (Boddie), and the fall armyworm, Spodoptera frugiperda (J. E. Smith). Management of these pests typically requires multiple insecticide applications from first silking until harvest, with commercial growers frequently spraying daily. This level of insecticide use presents problems for small growers, particularly for "pick-your-own" operations. Injection of oil into the corn ear silk channel 5-8 days after silking initiation has been used to suppress damage by these insects. Initial work with this technique in Georgia provided poor results. Subsequently, a series of experiments was conducted to evaluate the efficacy of silk channel injections as an application methodology for insecticides. A single application of synthetic insecticide, at greatly reduced per acre rates compared with common foliar applications, provided excellent control of Lepidoptera insects attacking the ear tip and suppressed damage by sap beetles (Nitidulidae). While this methodology is labor-intensive, it requires a single application of insecticide at reduced rates applied ∼2 wk prior to harvest, compared with potential daily applications at full rates up to the day of harvest with foliar insecticide applications. This methodology is not likely to eliminate the need for foliar applications because of other insect pests which do not enter through the silk channel or are not affected by the specific selective insecticide used in the silk channel injection, but would greatly reduce the number of applications required. This methodology may prove particularly useful for small acreage growers.
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Affiliation(s)
- A N Sparks
- University of Georgia, Tifton Campus, Tifton, 2360 Rainwater Rd., Tifton, GA 31793.
| | - L Gadal
- Institut National de la Recherche Agronomique, Montpellier, France
| | - X Ni
- USDA-ARS, Crop Genetics and Breeding Research Unit, Tifton, GA
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Blount JL, Buntin GD, Sparks AN. Host Preference of Megacopta cribraria (Hemiptera: Plataspidae) on Selected Edible Beans and Soybean. J Econ Entomol 2015; 108:1094-105. [PMID: 26470234 DOI: 10.1093/jee/tov090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 04/05/2015] [Indexed: 06/05/2023]
Abstract
Megacopta cribraria (F.) (Hemiptera: Plataspidae) is an Old World pest of legumes in Asia. Since its 2009 discovery in Georgia, it has become an economic pest of soybeans in the southeastern United States. The objective of this study was to determine the host preference of M. cribraria on edible legumes that might incur economic damage from injury of this pest. From 2012 to 2013 choice, no-choice, and field trials were conducted to evaluate the host suitability of several beans of commercial interest including pinto bean, lima bean, winter pea, and black-eyed pea. Choice and no-choice studies were conducted under greenhouse conditions. Plants in greenhouse trials were infested with adults and egg masses collected from kudzu and soybean and monitored for ∼2 wk. Field trials were allowed to be infested by naturally occurring M. cribraria populations. Sweep and whole plant counts of adults, egg masses, and nymphs were used to quantify field infestations. The legume crops found to be suitable developmental hosts are soybean, edamame, and pigeon pea. Low levels of development were seen on fava bean and none on the remaining entries.
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Affiliation(s)
- J L Blount
- UGA Entomology, UGA Griffin, 1109 Experiment St., Griffin, GA 30223
| | - G D Buntin
- UGA Entomology, UGA Griffin, 1109 Experiment St., Griffin, GA 30223.
| | - A N Sparks
- UGA Entomology, UGA Tifton, 2360 Rainwater Rd., Horticulture Building, Tifton, GA 31793
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Shelton AM, Olmstead DL, Burkness EC, Hutchison WD, Dively G, Welty C, Sparks AN. Multi-state trials of Bt sweet corn varieties for control of the corn earworm (Lepidoptera: Noctuidae). J Econ Entomol 2013; 106:2151-9. [PMID: 24224259 DOI: 10.1603/ec13146] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Field tests in 2010-2011 were performed in New York, Minnesota, Maryland, Ohio, and Georgia to compare Bt sweet corn lines expressing Cry1A.105 + Cry2Ab2 and Cry1Ab with their non-Bt isolines, with and without the use of foliar insecticides. The primary insect pest in all locations during the trial years was Heliocoverpa zea (Boddie), which is becoming the most serious insect pest of sweet corn in the United States. At harvest, the ears were measured for marketability according to fresh market and processing standards. For fresh market and processing, least squares regression showed significant effects of protein expression, state, and insecticide frequency. There was a significant effect of year for fresh market but not for processing. The model also showed significant effects of H. zea per ear by protein expression. Sweet corn containing two genes (Cry1A.105 + Cry2Ab2) and a single gene (Cry1Ab) provided high marketability, and both Bt varieties significantly outperformed the traditional non-Bt isolines in nearly all cases regardless of insecticide application frequency. For pest suppression of H. zea, plants expressing Bt proteins consistently performed better than non-Bt isoline plants, even those sprayed at conventional insecticide frequencies. Where comparisons in the same state were made between Cry1A.105 + Cry2Ab2 and Cry1Ab plants for fresh market, the product expressing Cry1A.105 + Cry2Ab2 provided better protection and resulted in less variability in control. Overall, these results indicate Cry1A.105 + Cry2Ab2 and Cry1Ab plants are suitable for fresh market and processing corn production across a diversity of growing regions and years. Our results demonstrate that Bt sweet corn has the potential to significantly reduce the use of conventional insecticides against lepidopteran pests and, in turn, reduce occupational and environmental risks that arise from intensive insecticide use.
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Affiliation(s)
- A M Shelton
- Department of Entomology, Cornell University, 630 W. North St., New York State Agricultural Experiment Station, Geneva, NY 14456, USA.
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Ni X, Sparks AN, Riley DG, Li X. Impact of applying edible oils to silk channels on ear pests of sweet corn. J Econ Entomol 2011; 104:956-964. [PMID: 21735916 DOI: 10.1603/ec10356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The impact of applying edible oils to corn silks on ear-feeding insects in sweet corn, Zea mays L., production was evaluated in 2006 and 2007. Six edible oils used in this experiment were canola, corn, olive, peanut, sesame, and soybean. Water and two commercial insecticidal oils (Neemix neem oil and nC21 Sunspray Ultrafine, a horticultural mineral oil) were used as the controls for the experiment. Six parameters evaluated in this experiment were corn earworm [Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)] damage rating, the number of sap beetle [Carpophilus spp. (Coleoptera: Nitidulidae)] adults and larvae, the number of corn silk fly (or picture-winged fly) (Diptera: Ulidiidae) larvae, common smut [Ustilago maydis (D.C.) Corda] infection rate, and corn husk coverage. Among the two control treatments, neem oil reduced corn earworm damage at both pre- and postpollination applications in 2006, but not in 2007, whereas the mineral oil applied at postpollination treatments reduced corn earworm damage in both years. The mineral oil also reduced the number of sap beetle adults, whereas the neem oil applied at postpollination attracted the most sap beetle adults in 2007. Among the six edible oil treatments, the corn and sesame oils applied at postpollination reduced corn earworm damage only in 2007. The application of the peanut oil at postpollination attracted more sap beetle adults in 2006, and more sap beetle larvae in 2007. Olive and neem oils significantly reduced husk coverage compared with the water control in both years. The mineral oil application consistently increased smut infection rate in both 2006 and 2007. Ramifications of using oil treatments in ear pest management also are discussed.
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Affiliation(s)
- Xinzhi Ni
- USDA-ARS, Crop Genetics and Breeding Research Unit, University of Georgia, Tifton, GA 31793-0748, USA.
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Klun JA, Plimmer JR, Bierl-Leonhardt BA, Sparks AN, Chapman OL. Trace chemicals: the essence of sexual communication systems in heliothis species. Science 2010; 204:1328-30. [PMID: 17813171 DOI: 10.1126/science.204.4399.1328] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Analysis of heptane-soluble compounds from ovipositors of Heliothis zea and Heliothis virescens shows that both species produce relatively large amounts of (Z)-11-hexadecenal, with traces of (Z)-9-hexadecenal, (Z)-7-hexadecenal, and hexadecanal. Heliothis virescens females differ from Heliothis zea in that they also produce trace amounts of tetradecanal, (Z)-9-tetradecenal, and (Z)-11-hexadecen-1-ol. In both species, trace compounds are essential to pheromonal activity and specificity of chemical signals.
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11
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Nischwitz C, Gitaitis RD, Mullis SW, Csinos AS, Langston DB, Sparks AN. First Report of Iris yellow spot virus in Spiny Sowthistle (Sonchus asper) in the United States. Plant Dis 2007; 91:1518. [PMID: 30780764 DOI: 10.1094/pdis-91-11-1518c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Iris yellow spot virus (IYSV) is a member of the genus Tospovirus in the family Bunyaviridae. Its known host range is very limited, and the currently known hosts include onion, leek, lisianthus, and alstroemeria (2). The virus is vectored by onion thrips (Thrips tabaci). Onion (Allium cepa) is grown as a winter crop in Georgia from September to April and is the only known host commercially grown in the region. However, the virus has been found across the onion-growing region in the state every year since its first occurrence during 2003 (3). Consequently, the virus must oversummer in other host(s) or its insect vector. Accordingly, samples of weeds were collected in the vicinity of onion fields and cull piles in the Vidalia region and tested for the presence of IYSV by a double-antibody sandwich (DAS)-ELISA (Agdia, Inc., Elkhart, IN). One of three nonsymptomatic spiny sowthistle samples tested positive by ELISA for IYSV. Total RNA was extracted from the leaf using the RNeasy Plant Mini Kit (Qiagen, Valencia, CA) following the manufacturer's protocol. Two microliters were used for reverse transcription (RT)-PCR with the forward primer (5'-TCAGAAATCGAGAAACTT-3') and reverse primer (5'-TAATTATATCTATCTTTCTTGG-3') for the IYSV nucleocapsid gene (1). A band of the expected size (approximately 800 bp) was obtained and sequenced. The sequence from the sowthistle (GenBank Accession No. EU078327) matched IYSV sequences from Georgia and Peru in a BLAST search in GenBank (closest matches with Accession Nos. DQ838584, DQ838592, DQ838593, and DQ658242). This is to our knowledge, the first confirmed report of IYSV infecting spiny sowthistle. The distribution of IYSV in sowthistle and its role as an oversummering host for IYSV is currently an on-going study. References: (1) L. du Toit et al. Plant Dis. 88:222, 2004. (2) D. H. Gent et al. Plant Dis. 90:1468, 2006. (3) S. W. Mullis et al. Plant Dis. 88:1285, 2004.
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Affiliation(s)
- C Nischwitz
- University of Georgia, Department of Plant Pathology, Coastal Plain Experiment Station, P.O. Box 748, Tifton 31794
| | - R D Gitaitis
- University of Georgia, Department of Plant Pathology, Coastal Plain Experiment Station, P.O. Box 748, Tifton 31794
| | - S W Mullis
- University of Georgia, Department of Plant Pathology, Coastal Plain Experiment Station, P.O. Box 748, Tifton 31794
| | - A S Csinos
- University of Georgia, Department of Plant Pathology, Coastal Plain Experiment Station, P.O. Box 748, Tifton 31794
| | - D B Langston
- University of Georgia, Department of Plant Pathology, Coastal Plain Experiment Station, P.O. Box 748, Tifton 31794
| | - A N Sparks
- University of Georgia, Department of Entomology, Cooperative Extension Service, Tifton 31793-1209
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Greenberg SM, Sparks AN, Norman JW, Coleman R, Bradford JM, Yang C, Sappington TW, Showler A. Chemical cotton stalk destruction for maintenance of host-free periods for the control of overwintering boll weevil in tropical and subtropical climates. Pest Manag Sci 2007; 63:372-80. [PMID: 17348066 DOI: 10.1002/ps.1348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
In the Lower Rio Grande Valley (LRGV) of Texas, cotton regrows and produces fruit from undestroyed stalks throughout the winter, and in spring weevils from such locations become a serious threat. The success of the boll weevil eradication program, which was reintroduced in the LRGV in 2005, will be dependent on thorough stalk destruction following harvest. However, adverse weather conditions and conservation tillage often impede immediate and complete stalk destruction using typical tool implements, and alternative stalk control methods are needed. This study provides an examination of the efficacy for cotton stalk destruction of different herbicides (thifensulfuron-methyl + tribenuron-methyl, dicamba-diolamine, 2,4-D-dimethylammonium, flumioxazin, 2,4-DB-dimethylammonium and carfentrazone-ethyl) and their rates, spray volumes and application timings on shredded or standing cotton stalks after stripper or picker harvest. None of the tested herbicides, except 2,4-D-dimethylammonium, stopped post-harvest cotton regrowth and fruiting. 2,4-D-dimethylammonium sprayed once (0 or 7 days) after cotton was harvested at 1 lb AE acre(-1) (1.12 kg ha(-1)), in a spray volume of 10 gal water acre(-1) (93.5 L ha(-1)) with 5 mL L(-1) surfactant, was highly effective in stalk destruction (72-90%). The best results were achieved when the herbicide was applied immediately after the cotton was shredded, followed by standing stripper-harvested and standing picker-harvested cotton. 2,4-D-dimethylammonium applied twice, 0 and 14 (or 21) days after cotton harvest, was 100% effective in killing stalks, regardless of whether they were shredded or standing, or whether harvest was by stripper or picker. These findings showed that 2,4-D-dimethylammonium cotton stalk destruction eliminated food and reproductive opportunities for managing overwintering boll weevils [Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae)].
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Affiliation(s)
- Shoil M Greenberg
- USDA, ARS, Areawide Pest Management Research Unit, Weslaco, TX 78596, USA.
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Mullis SW, Langston DB, Gitaitis RD, Sherwood JL, Csinos AC, Riley DG, Sparks AN, Torrance RL, Cook MJ. First Report of Vidalia Onion (Allium cepa) Naturally Infected with Tomato spotted wilt virus and Iris yellow spot virus (Family Bunyaviridae, Genus Tospovirus) in Georgia. Plant Dis 2004; 88:1285. [PMID: 30795333 DOI: 10.1094/pdis.2004.88.11.1285b] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vidalia onion is an important crop in Georgia's agriculture with worldwide recognition as a specialty vegetable. Vidalia onions are shortday, Granex-type sweet onions grown within a specific area of southeastern Georgia. Tomato spotted wilt virus (TSWV) has been endemic to Georgia crops for the past decade, but has gone undetected in Vidalia onions. Tobacco thrips (Frankliniella fusca) and Western flower thrips (Frankliniella occidentalis) are the primary vectors for TSWV in this region, and a number of plant species serve as reproductive reservoirs for the vector or virus. Iris yellow spot virus (IYSV), an emerging tospovirus that is potentially a devastating pathogen of onion, has been reported in many locations in the western United States (2,4). Thrips tabaci is the known vector for IYSV, but it is unknown if noncrop plants play a role in its epidemiology in Georgia. During October 2003, a small (n = 12) sampling of onions with chlorosis and dieback of unknown etiology from the Vidalia region was screened for a variety of viruses, and TSWV and IYSV infections were serologically detected. Since that time, leaf and bulb tissues from 4,424 onion samples were screened for TSWV and IYSV using double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) with commercial kits (Agdia Inc., Elkhart, IN). Samples were collected from 53 locations in the Vidalia region during the growing season between November 2003 and March 2004. Plants exhibiting stress, such as tip dieback, necrotic lesions, chlorosis or environmental damage were selected. Of these, 306 were positive for TSWV and 396 were positive for IYSV using positive threshold absorbance of three times the average plus two standard deviations of healthy negative onion controls. Positive serological findings of the onion tissues were verified by immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) for TSWV (3) and RT-PCR for IYSV (1). In both instances, a region of the viral nucleocapsid (N) gene was amplified. The PCR products were analyzed with gel electrophoresis with an ethidium bromide stain in 0.8% agarose. Eighty-six percent (n = 263) of the TSWV ELISA-positive samples exhibited the expected 774-bp product and 55 percent (n = 217) of the IYSV ELISA-positive samples exhibited the expected 962-bp product. The reduced success of the IYSV verification could be attributed to the age and deteriorated condition of the samples at the time of amplification. Thrips tabaci were obtained from onion seedbeds and cull piles within the early sampling (n = 84) and screened for TSWV by the use of an indirect-ELISA to the nonstructural (NSs) protein of TSWV. Of the thrips sampled, 25 were positive in ELISA. While the incidence of IYSV and TSWV in the Vidalia onion crop has been documented, more research is needed to illuminate their potential danger to Vidalia onions. References: (1) I. Cortês et al. Phytopathology 88:1276, 1998. (2) L. J. du Toit et al. Plant Dis. 88:222, 2004. (3) R. K. Jain et al. Plant Dis. 82:900, 1998. (4) J. W. Moyer et al. (Abstr.) Phytopathology 93(suppl.):S115, 2003.
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Affiliation(s)
- S W Mullis
- Department of Plant Pathology, University of Georgia, P.O. Box 748, Tifton 31793
| | - D B Langston
- Department of Plant Pathology, University of Georgia, P.O. Box 748, Tifton 31793
| | - R D Gitaitis
- Department of Plant Pathology, University of Georgia, P.O. Box 748, Tifton 31793
| | - J L Sherwood
- Department of Plant Pathology, University of Georgia, P.O. Box 748, Tifton 31793
| | - A C Csinos
- Department of Plant Pathology, University of Georgia, P.O. Box 748, Tifton 31793
| | - D G Riley
- Department of Entomology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793
| | - A N Sparks
- Cooperative Extension Service, University of Georgia, Tifton 31793
| | - R L Torrance
- Cooperative Extension Service, University of Georgia, Tifton 31793
| | - M J Cook
- Cooperative Extension Service, University of Georgia, Tifton 31793
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Greenberg SM, Sappington TW, Elzen GW, Norman JW, Sparks AN. Effects of insecticides and defoliants applied alone and in combination for control of overwintering boll weevil (Anthonomus grandis; Coleoptera: Curculionidae)--laboratory and field studies. Pest Manag Sci 2004; 60:849-858. [PMID: 15382499 DOI: 10.1002/ps.878] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In laboratory, greenhouse and field tests, we determined the effects of combining full rates of the defoliants tribufos and thidiazuron and the herbicide thifensulfuron-methyl with half rates of the insecticides lambda-cyhalothrin or azinphos-methyl, and the combination of tribufos and thidiazuron, both in half rates, on mortality of the boll weevil, Anthonomus grandis grandis Boheman and on the quality of defoliation. Tribufos, 0.47 kg ha(-1) and tribufos, 0.235 kg ha(-1) + thidiazuron, 0.125 kg ha(-1) exhibited a slightly toxic effect to boll weevil, while tribufos, 0.47 kg ha(-1) + lambda-cyhalothrin, 0.019 kg ha(-1), tribufos, 0.47 kg ha(-1) + azinphos-methyl, 0.14 kg ha(-1), and tribufos, 0.235 kg ha(-1) + thidiazuron, 0.125 kg ha(-1) + azinphos-methyl, 0.14 kg ha(-l), provided control of boll weevil as good as or better than full-rate azinphos-methyl or lambda-cyhalothrin alone owing to synergistic effects. Thidiazuron or thifensulfuron-methyl alone or in combination with insecticides did not affect boll weevil mortality. Treatment with tribufos + thidiazuron, both at half rate, significantly increased defoliation compared to full rates of tribufos or thidiazuron alone, and provided adequate defoliation for approximately the same cost per hectare.
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Affiliation(s)
- Shoil M Greenberg
- USDA, ARS, Areawide Pest Management Research Unit, Weslaco, Texas 78596, USA.
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Liu TX, Sparks AN, Chen W, Liang GM, Brister C. Toxicity, persistence, and efficacy of indoxacarb on cabbage looper (Lepidoptera: Noctuidae) on cabbage. J Econ Entomol 2002; 95:360-367. [PMID: 12020014 DOI: 10.1603/0022-0493-95.2.360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Toxicity of indoxacarb was bioassayed against eggs and young (first and second instars) and older larvae (third and fourth instars) of cabbage looper, Trichoplusia ni (Hübner), on cabbage (Brassicae oleracea variety capitata L.), and persistence of field-aged leaf residues of indoxacarb was bioassayed with second and third instars of T. ni on cabbage. Efficacies of indoxacarb and several other newer insecticides to T. ni were tested under field conditions for two seasons in south Texas. LC50 and LC90 values for T. ni eggs were relatively high, indicating that indoxacarb has little ovicidal effects on T. ni eggs. Indoxacarb was highly toxic to T. ni larvae, having low LC50 and LC90 values. Bioassays of field-aged leaf residues of indoxacarb tested in the spring of 1998 (0-, 3-, 5-, and 12-d-old residues) and the fall of 2000 (0-, 3-, 5-, 7-, 9-, and 13-d-old residues) indicated that ingesting indoxacarb was highly toxic to the second and third instars of T. ni, giving 100% mortality for the second instars at 2 d after exposure, and 100% mortality for third instars at 5 d after exposure. Two trials conducted under field conditions show that indoxacarb at 0.072 g (AI) /ha rate was effective against T. ni in cabbage, providing marketable cabbage with three applications per season. In addition, indoxacarb was as effective as spinosad and chlorfenapyr and significantly more effective than tebufenozide and emamectin benzoate.
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Affiliation(s)
- Tong-Xian Liu
- Department of Entomology, Texas Agricultural Research and Extension Center, Texas A&M University, Weslaco 78596-8399, USA.
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