{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/136970"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/136970","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Improving Integrated Pest Management in Sweet Corn System","abstract":"Corn earworm (CEW), Helicoverpa zea (Boddie), (Lepidoptera: Noctuidae) is a common insect pest of sweet corn in the United States. The larvae cause chewing damage on corn ears rendering them unmarketable. Traditionally, growers have controlled CEW in sweet corn using multiple applications of insecticides such as pyrethroids during ear development and/or by planting transgenic sweet corn hybrids that produce insecticidal proteins derived from the bacteria Bacillus thuringiensis. However, over the past decade, CEW populations have developed resistance to both the Cry proteins found in many of the Bt sweet corn hybrids and pyrethroid insecticides, which has made management of this pest difficult. In this thesis I investigate strategies that can help improve pest management for this difficult pest in sweet corn. First, I assessed the efficacy of two novel insecticides that could add different modes of action to the insecticide options in sweet corn; these included a product containing a suspension of nucleopolyhedrovirus particles that are specific to CEW and a product that contains insecticidal peptides derived from spider venom. These were tested in conjunction with Bt transgenic corn to enhance their efficacy. Unfortunately, neither of the insecticides provided any effective level of control of CEW. Additionally, I assessed if sweet corn growers could reduce their frequency of insecticide applications by spraying based on a moth capture action threshold compared with standard frequent insecticide applications applied every 2-3 days. I found that a spray program using thresholds as well as more IPM-compatible insecticides provided similar levels of control while reducing the number of sprays needed. In other studies, I assessed the non-target risks of the different insecticides commonly used in sweet corn. I examined the potential for bifenthrin, spinetoram, and chlorantraniliprole to repel bees and other beneficial arthropods after application in sweet corn; repellency could impact their risk of nontarget effects by reducing exposure. I found that there was no significant effect on the number of times honey bees visited the corn tassels or the number of other beneficial arthropods found. Lastly, I examined the residual toxicity of bifenthrin, spinetoram, chlorantraniliprole, and isocycloseram on lady beetles (Coleoptera: Coccinellidae) after 2, 4, and 6 days in the field. I found there was higher mortality in the bifenthrin and isocycloseram treatments across all three application dates than spinetoram, chlorantroniliprole and untreated control.","abstract_html":"Corn earworm (CEW), Helicoverpa zea (Boddie), (Lepidoptera: Noctuidae) is a common insect pest of sweet corn in the United States. The larvae cause chewing damage on corn ears rendering them unmarketable. Traditionally, growers have controlled CEW in sweet corn using multiple applications of insecticides such as pyrethroids during ear development and/or by planting transgenic sweet corn hybrids that produce insecticidal proteins derived from the bacteria Bacillus thuringiensis. However, over the past decade, CEW populations have developed resistance to both the Cry proteins found in many of the Bt sweet corn hybrids and pyrethroid insecticides, which has made management of this pest difficult. In this thesis I investigate strategies that can help improve pest management for this difficult pest in sweet corn. First, I assessed the efficacy of two novel insecticides that could add different modes of action to the insecticide options in sweet corn; these included a product containing a suspension of nucleopolyhedrovirus particles that are specific to CEW and a product that contains insecticidal peptides derived from spider venom. These were tested in conjunction with Bt transgenic corn to enhance their efficacy. Unfortunately, neither of the insecticides provided any effective level of control of CEW. Additionally, I assessed if sweet corn growers could reduce their frequency of insecticide applications by spraying based on a moth capture action threshold compared with standard frequent insecticide applications applied every 2-3 days. I found that a spray program using thresholds as well as more IPM-compatible insecticides provided similar levels of control while reducing the number of sprays needed. In other studies, I assessed the non-target risks of the different insecticides commonly used in sweet corn. I examined the potential for bifenthrin, spinetoram, and chlorantraniliprole to repel bees and other beneficial arthropods after application in sweet corn; repellency could impact their risk of nontarget effects by reducing exposure. I found that there was no significant effect on the number of times honey bees visited the corn tassels or the number of other beneficial arthropods found. Lastly, I examined the residual toxicity of bifenthrin, spinetoram, chlorantraniliprole, and isocycloseram on lady beetles (Coleoptera: Coccinellidae) after 2, 4, and 6 days in the field. I found there was higher mortality in the bifenthrin and isocycloseram treatments across all three application dates than spinetoram, chlorantroniliprole and untreated control.","abstract_has_math":false,"creators":["Currin, Brian Booker"],"institution":"Virginia Tech","degree_name":"Master of Science in Life Sciences","degree_level":"masters","degree_discipline":"Entomology","degree_department":"Entomology","school":null,"contributors":[],"advisors":[],"committee_chairs":["Kuhar, Thomas P."],"committee_members":["Nault, Brian A.","Frank, Daniel L."],"year":2025,"date_issued":"2025-08-05","date_published":"2025-08-05","updated_at":"2026-07-22T22:19:18Z","subjects":["sweet corn","corn earworm","Helicoverpa zea","natural enemies","IPM"],"languages":["en"],"rights":["Creative Commons Attribution-NonCommercial 4.0 International"],"rights_urls":["http://creativecommons.org/licenses/by-nc/4.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:44443"],"render_values":[{"text":"vt_gsexam:44443","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/136970","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Kuhar, Thomas P."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Nault, Brian A.","Frank, Daniel L."]},{"key":"dc:contributor.department","label":"Department","values":["Entomology"]},{"key":"dc:creator","label":"Author","values":["Currin, Brian Booker"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-08-06T08:00:46Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-08-06T08:00:46Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-08-05"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Entomology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science in Life Sciences"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["sweet corn","corn earworm","Helicoverpa zea","natural enemies","IPM"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Creative Commons Attribution-NonCommercial 4.0 International"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://creativecommons.org/licenses/by-nc/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:44443"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/136970"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Corn earworm (CEW), Helicoverpa zea (Boddie), (Lepidoptera: Noctuidae) is a common insect pest of sweet corn in the United States. The larvae cause chewing damage on corn ears rendering them unmarketable. Traditionally, growers have controlled CEW in sweet corn using multiple applications of insecticides such as pyrethroids during ear development and/or by planting transgenic sweet corn hybrids that produce insecticidal proteins derived from the bacteria Bacillus thuringiensis. However, over the past decade, CEW populations have developed resistance to both the Cry proteins found in many of the Bt sweet corn hybrids and pyrethroid insecticides, which has made management of this pest difficult. In this thesis I investigate strategies that can help improve pest management for this difficult pest in sweet corn. First, I assessed the efficacy of two novel insecticides that could add different modes of action to the insecticide options in sweet corn; these included a product containing a suspension of nucleopolyhedrovirus particles that are specific to CEW and a product that contains insecticidal peptides derived from spider venom. These were tested in conjunction with Bt transgenic corn to enhance their efficacy. Unfortunately, neither of the insecticides provided any effective level of control of CEW. Additionally, I assessed if sweet corn growers could reduce their frequency of insecticide applications by spraying based on a moth capture action threshold compared with standard frequent insecticide applications applied every 2-3 days. I found that a spray program using thresholds as well as more IPM-compatible insecticides provided similar levels of control while reducing the number of sprays needed. In other studies, I assessed the non-target risks of the different insecticides commonly used in sweet corn. I examined the potential for bifenthrin, spinetoram, and chlorantraniliprole to repel bees and other beneficial arthropods after application in sweet corn; repellency could impact their risk of nontarget effects by reducing exposure. I found that there was no significant effect on the number of times honey bees visited the corn tassels or the number of other beneficial arthropods found. Lastly, I examined the residual toxicity of bifenthrin, spinetoram, chlorantraniliprole, and isocycloseram on lady beetles (Coleoptera: Coccinellidae) after 2, 4, and 6 days in the field. I found there was higher mortality in the bifenthrin and isocycloseram treatments across all three application dates than spinetoram, chlorantroniliprole and untreated control."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Corn earworm (CEW) is a major pest of sweet corn in Virginia. The adult moths lay their eggs on the silks of a corn ear. After hatching, the larvae crawl into the ear where they feed on the kernels within. This causes unsightly damage that renders the ears unmarketable and causes significant economic loss for farmers. CEW is a particularly difficult pest because of their ability to develop resistance to chemical pesticide sprays. They have also developed resistance to the proteins derived from the Bacillus thuringiensis bacterium in transgenic corn crops. This research explored alternative pest control options, including the use of a natural virus (nucleopolyhedrovirus) and spider venom derived peptides combined with Bt corn. These alternatives did not provide strong enough control to be recommended for widespread use. I also tested a more targeted spraying strategy based on the number of moths caught in traps. This method, which used fewer and less harmful insecticides, worked just as well as traditional, routine spraying programs. Another part of the study looked at whether three commonly used insecticides (bifenthrin, spinetoram, and chlorantraniliprole) repelled bees or other helpful insects in sweet corn fields. I found no evidence that these insecticides reduced bee visits or affected other beneficial species immediately after spraying. Finally, I tested how long different insecticides remained harmful to lady beetles, which are important natural predators of pests. Bifenthrin and isocycloseram caused more deaths in lady beetles than the other treatments, even several days after spraying."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science in Life Sciences"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Improving Integrated Pest Management in Sweet Corn System"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Kuhar, Thomas P."],"dc:contributor.committeemember":["Nault, Brian A.","Frank, Daniel L."],"dc:contributor.department":["Entomology"],"dc:creator":["Currin, Brian Booker"],"dc:date.accessioned":["2025-08-06T08:00:46Z"],"dc:date.available":["2025-08-06T08:00:46Z"],"dc:date.issued":["2025-08-05"],"dc:description.abstract":["Corn earworm (CEW), Helicoverpa zea (Boddie), (Lepidoptera: Noctuidae) is a common insect pest of sweet corn in the United States. The larvae cause chewing damage on corn ears rendering them unmarketable. Traditionally, growers have controlled CEW in sweet corn using multiple applications of insecticides such as pyrethroids during ear development and/or by planting transgenic sweet corn hybrids that produce insecticidal proteins derived from the bacteria Bacillus thuringiensis. However, over the past decade, CEW populations have developed resistance to both the Cry proteins found in many of the Bt sweet corn hybrids and pyrethroid insecticides, which has made management of this pest difficult. In this thesis I investigate strategies that can help improve pest management for this difficult pest in sweet corn. First, I assessed the efficacy of two novel insecticides that could add different modes of action to the insecticide options in sweet corn; these included a product containing a suspension of nucleopolyhedrovirus particles that are specific to CEW and a product that contains insecticidal peptides derived from spider venom. These were tested in conjunction with Bt transgenic corn to enhance their efficacy. Unfortunately, neither of the insecticides provided any effective level of control of CEW. Additionally, I assessed if sweet corn growers could reduce their frequency of insecticide applications by spraying based on a moth capture action threshold compared with standard frequent insecticide applications applied every 2-3 days. I found that a spray program using thresholds as well as more IPM-compatible insecticides provided similar levels of control while reducing the number of sprays needed. In other studies, I assessed the non-target risks of the different insecticides commonly used in sweet corn. I examined the potential for bifenthrin, spinetoram, and chlorantraniliprole to repel bees and other beneficial arthropods after application in sweet corn; repellency could impact their risk of nontarget effects by reducing exposure. I found that there was no significant effect on the number of times honey bees visited the corn tassels or the number of other beneficial arthropods found. Lastly, I examined the residual toxicity of bifenthrin, spinetoram, chlorantraniliprole, and isocycloseram on lady beetles (Coleoptera: Coccinellidae) after 2, 4, and 6 days in the field. I found there was higher mortality in the bifenthrin and isocycloseram treatments across all three application dates than spinetoram, chlorantroniliprole and untreated control."],"dc:description.abstractgeneral":["Corn earworm (CEW) is a major pest of sweet corn in Virginia. The adult moths lay their eggs on the silks of a corn ear. After hatching, the larvae crawl into the ear where they feed on the kernels within. This causes unsightly damage that renders the ears unmarketable and causes significant economic loss for farmers. CEW is a particularly difficult pest because of their ability to develop resistance to chemical pesticide sprays. They have also developed resistance to the proteins derived from the Bacillus thuringiensis bacterium in transgenic corn crops. This research explored alternative pest control options, including the use of a natural virus (nucleopolyhedrovirus) and spider venom derived peptides combined with Bt corn. These alternatives did not provide strong enough control to be recommended for widespread use. I also tested a more targeted spraying strategy based on the number of moths caught in traps. This method, which used fewer and less harmful insecticides, worked just as well as traditional, routine spraying programs. Another part of the study looked at whether three commonly used insecticides (bifenthrin, spinetoram, and chlorantraniliprole) repelled bees or other helpful insects in sweet corn fields. I found no evidence that these insecticides reduced bee visits or affected other beneficial species immediately after spraying. Finally, I tested how long different insecticides remained harmful to lady beetles, which are important natural predators of pests. Bifenthrin and isocycloseram caused more deaths in lady beetles than the other treatments, even several days after spraying."],"dc:description.degree":["Master of Science in Life Sciences"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:44443"],"dc:identifier.uri":["https://hdl.handle.net/10919/136970"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["Creative Commons Attribution-NonCommercial 4.0 International"],"dc:rights.uri":["http://creativecommons.org/licenses/by-nc/4.0/"],"dc:subject":["sweet corn","corn earworm","Helicoverpa zea","natural enemies","IPM"],"dc:title":["Improving Integrated Pest Management in Sweet Corn System"],"dc:type":["Thesis"],"thesis:degree_discipline":["Entomology"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science in Life Sciences"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:18Z"}