1
|
Calvin W, Yang F, Brown SA, Catchot AL, Crow WD, Cook DR, Gore J, Kurtz R, Lorenz GM, Seiter NJ, Stewart SD, Towles T, Kerns DL. Development of Economic Thresholds Toward Bollworm (Lepidoptera: Noctuidae), Management in Bt Cotton, and Assessment of the Benefits From Treating Bt Cotton With Insecticide. JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:2493-2504. [PMID: 34625803 DOI: 10.1093/jee/toab173] [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: 04/30/2021] [Indexed: 06/13/2023]
Abstract
Widespread field-evolved resistance of bollworm [Helicoverpa zea (Boddie)] to Cry1 and Cry2 Bt proteins has threatened the utility of Bt cotton for managing bollworm. Consequently, foliar insecticide applications have been widely adopted to provide necessary additional control. Field experiments were conducted across the Mid-South and in Texas to devise economic thresholds for foliar insecticide applications targeting bollworm in cotton. Bt cotton technologies including TwinLink (TL; Cry1Ab+Cry2Ae), TwinLink Plus (TLP; Cry1Ab+Cry2Ae+Vip3Aa), Bollgard II (BG2; Cry1Ac+Cry2Ab), Bollgard 3 (BG3; Cry1Ac+Cry2Ab+Vip3Aa), WideStrike (WS; Cry1Ac+Cry1F), WideStrike 3 (WS3; Cry1Ac+Cry1F+Vip3Aa), and a non-Bt (NBT) variety were evaluated. Gain threshold, economic injury level, and economic thresholds were determined. A 6% fruiting form injury threshold was selected and compared with preventive treatments utilizing chlorantraniliprole. Additionally, the differences in yield from spraying bollworms was compared among Bt cotton technologies. The 6% fruiting form injury threshold resulted in a 25 and 75% reduction in insecticide applications relative to preventive sprays for WS and BG2, respectively. All Bt technologies tested in the current study exhibited a positive increase in yield from insecticide application. The frequency of yield increase from spraying WS was comparable to that of NBT. Significant yield increases due to insecticide application occurred less frequently in triple-gene Bt cotton. However, their frequencies were close to the dual-gene Bt cotton, except for WS. The results of our study suggest that 6% fruiting form injury is a viable threshold, and incorporating a vetted economic threshold into an Integrated Pest Management program targeting bollworm should improve the sustainability of cotton production.
Collapse
Affiliation(s)
- Wilfrid Calvin
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| | - Fei Yang
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| | - Sebe A Brown
- Dean Lee Research Station, Louisisana State University, 8105 Tom Bowman Drive, Alexandria, LA 71302, USA
| | - Angus L Catchot
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, P.O. Box 9775, Mississippi State, MS 39762, USA
| | - Whitney D Crow
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Donald R Cook
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Jeffrey Gore
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Ryan Kurtz
- Cotton Incorporated, 6399 Weston Pkwy, Cary, NC 27513, USA
| | - Gustav M Lorenz
- Department of Entomology and Plant Pathology, University of Arkansas, 2001 Highway 70 E., Lonoke, AR 72086, USA
| | - Nicholas J Seiter
- Crop Sciences, 380 National Soybean Research Center, University of Illinois, 1101 W. Peabody Drive, Urbana, IL 61801, USA
| | - Scott D Stewart
- West Tennessee REC, University of Tennessee, 605 Airways Boulevard, Jackson, TN 38301, USA
| | - Tyler Towles
- Macon Ridge Research Station, Louisisana State University, 212A Macon Ridge Road, Winnsboro, LA 71295, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| |
Collapse
|
2
|
Reisig DD, Cook D, Greene JK, Caprio M, Gore J, Musser F, Reay-Jones F. Vertical and temporal distribution of Helicoverpa zea (Lepidoptera: Noctuidae) larvae in determinate and indeterminate soybean. BULLETIN OF ENTOMOLOGICAL RESEARCH 2021; 111:282-288. [PMID: 32945252 DOI: 10.1017/s0007485320000619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Most oviposition by Helicoverpa zea (Boddie) occurs near the top of the canopy in soybean, Glycine max (L.) Merr, and larval abundance is influenced by the growth habit of plants. However, the vertical distribution of larvae within the canopy is not as well known. We evaluated the vertical distribution of H. zea larvae in determinate and indeterminate varieties, hypothesizing that larval distribution in the canopy would vary between these two growth habits and over time. We tested this hypothesis in a naturally infested replicated field experiment and two experimentally manipulated cage experiments. In the field experiment, flowering time was synchronized between the varieties by manipulating planting date, while infestation timing was manipulated in the cage experiments. Larvae were recovered using destructive sampling of individual soybean plants, and their vertical distribution by instar was recorded from three sampling points over time in each experiment. While larval population growth and development varied between the determinate and indeterminate varieties within and among experiments, we found little evidence that larvae have preference for different vertical locations in the canopy. This study lends support to the hypothesis that larval movement and location within soybean canopies do not result entirely from oviposition location and nutritional requirements.
Collapse
Affiliation(s)
- Dominic D Reisig
- Department of Entomology and Plant Pathology, Vernon G. James Research and Extension Center, North Carolina State University, 207 Research Station Rd., Plymouth, NC27962, USA
| | - Don Cook
- Delta Research & Extension Center, Mississippi State University, P.O. Box 197, Stoneville, MS38776, USA
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Edisto Research and Education Center, Clemson University, 64 Research Road, Blackville, SC29817, USA
| | - Michael Caprio
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Box 9775, Mississippi State, MS39762, USA
| | - Jeff Gore
- Delta Research & Extension Center, Mississippi State University, P.O. Box 197, Stoneville, MS38776, USA
| | - Fred Musser
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Box 9775, Mississippi State, MS39762, USA
| | - Francis Reay-Jones
- Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, 2200 Pocket Road, Florence, SC29506-9727, USA
| |
Collapse
|
3
|
Babu A, Reisig DD, Pes MP, Ranger CM, Chamkasem N, Reding ME. Effects of chlorantraniliprole residual on Helicoverpa zea in Bt and non-Bt cotton. PEST MANAGEMENT SCIENCE 2021; 77:2367-2374. [PMID: 33415822 DOI: 10.1002/ps.6263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 12/30/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Helicoverpa zea is managed with foliar applications of chlorantraniliprole in cotton varieties that do not express the Vip3Aa19 toxin in the US Cotton Belt. Foliar insecticides and Bt could interact to influence larval susceptibility. Therefore, it has been suggested that chlorantraniliprole can be used as a tool for Bt resistance management. We designed field and laboratory studies to test the hypothesis that the interaction of Bt toxin and chlorantraniliprole application would result in lower H. zea larval survival when compared to the individual effect of Bt or chlorantraniliprole alone. We also tested for these interactions over time, since chlorantraniliprole residual has not been studied in cotton. RESULTS Results from two field experiments and two laboratory experiments were similar. We found no interactions with Bt and chlorantraniliprole using data not corrected for natural mortality in untreated plots, indicating that these factors did not interact to influence survival. Moreover, we found that Bt and chlorantraniliprole did not interact to influence larval weight and instar. Chlorantraniliprole had lethal and sublethal effects on H. zea larval growth parameters feeding on cotton leaves up to 22 days after application, the final time period that we tested. Finally, concentration of chlorantraniliprole in the leaf was associated with larval survival for the duration of this study, but not larval growth or instar. CONCLUSION Our findings complement the recommendation to use chlorantraniliprole for managing H. zea in cotton, given its long-residual effects. However, the utility of chlorantraniliprole as a Bt-resistance management tool for H. zea remains unclear. © 2021 Society of Chemical Industry.
Collapse
Affiliation(s)
- Arun Babu
- Department of Entomology and Plant Pathology, Vernon G. James Research and Extension Center, North Carolina State University, Plymouth, NC, USA
- Department of Entomology, College of Agricultural and Environmental Sciences, University of Georgia, 413 Biological Sciences, Athens, GA, 30602, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, Vernon G. James Research and Extension Center, North Carolina State University, Plymouth, NC, USA
| | | | - Christopher M Ranger
- Application Technology Research Unit, USDA-Agricultural Research Service, Wooster, OH, USA
| | - Narong Chamkasem
- Southeast Regional Laboratory, U.S. Food and Drug Administration, Atlanta, GA, USA
| | - Michael E Reding
- Application Technology Research Unit, USDA-Agricultural Research Service, Wooster, OH, USA
| |
Collapse
|
4
|
Del Pozo-Valdivia AI, Reisig DD, Braswell L, Greene JK, Roberts P, Taylor SV. Economic Injury Levels for Bt-resistant Helicoverpa zea (Lepidoptera: Noctuidae) in Cotton. JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:747-756. [PMID: 33615386 DOI: 10.1093/jee/toab012] [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: 12/16/2020] [Indexed: 06/12/2023]
Abstract
Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.
Collapse
Affiliation(s)
- Alejandro I Del Pozo-Valdivia
- Department of Entomology, Hampton Roads Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Virginia Beach, VA, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC, USA
| | - Lewis Braswell
- Product Biology Division, Syngenta Crop Protection Inc., Greensboro, NC, USA
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Edisto Research and Education Center, Clemson University, Blackville, SC, USA
| | - Phillip Roberts
- Department of Entomology, University of Georgia, Tifton Campus, Tifton, GA, USA
| | - Sally V Taylor
- Department of Entomology, Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk, VA, USA
| |
Collapse
|
5
|
Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton. Toxins (Basel) 2020; 12:toxins12090551. [PMID: 32872277 PMCID: PMC7551585 DOI: 10.3390/toxins12090551] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/10/2020] [Accepted: 08/26/2020] [Indexed: 01/02/2023] Open
Abstract
Insecticidal toxins from Bacillus thuringiensis (Bt) are valuable tools for pest management worldwide, contributing to the management of human disease insect vectors and phytophagous insect pests of agriculture and forestry. Here, we report the effects of dual and triple Bt toxins expressed in transgenic cotton cultivars on the fitness and demographic performance of Helicoverpa zea (Boddie)—a noctuid pest, known as cotton bollworm and corn earworm. Life-history traits were determined for individuals of three field populations from a region where H. zea overwintering is likely. Triple-gene Bt cotton cultivars that express Cry and Vip3Aa toxins killed 100% of the larvae in all populations tested. In contrast, dual-gene Bt cotton that express Cry1Ac+Cry1F and Cry1Ac+Cry2Ab allowed population growth with the intrinsic rate of population growth (rm) 38% lower than on non-Bt cotton. The insects feeding on Bt cotton plants that express Cry1Ac+Cry2Ab, Cry1Ac+Cry1F, or Cry1Ab+Cry2Ae exhibited reduced larval weight, survival rate, and increased development time. Additionally, fitness parameters varied significantly among the insect populations, even on non-Bt cotton plants, likely because of their different genetic background and/or previous Bt toxin exposure. This is the first report of the comparative fitness of H. zea field populations on dual-gene Bt cotton after the recent reports of field resistance to certain Bt toxins. These results document the population growth rates of H. zea from an agricultural landscape with 100% Bt cotton cultivars. Our results will contribute to the development and validation of resistance management recommendations.
Collapse
|
6
|
Rabelo MM, Matos JML, Orozco-Restrepo SM, Paula-Moraes SV, Pereira EJG. Like Parents, Like Offspring? Susceptibility to Bt Toxins, Development on Dual-Gene Bt Cotton, and Parental Effect of Cry1Ac on a Nontarget Lepidopteran Pest. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:1234-1242. [PMID: 32221528 DOI: 10.1093/jee/toaa051] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Indexed: 06/10/2023]
Abstract
An important step to devise appropriate pest management strategies for armyworms (Lepidoptera: Noctuidae) in Bacillus thuringiensis Berliner (Bt) crops is to determine the lethal, sublethal, and parental effects of Bt toxins on target and nontarget pest species. Here we documented the susceptibility of black armyworm, Spodoptera cosmioides (Walker), to three Cry toxins and its life-history traits feeding on dual-toxin Bt cotton and an artificial diet containing sublethal concentrations of Cry1Ac. In concentration-response bioassays, black armyworm larvae showed low susceptibility to Cry toxins, with 853 ng/cm2 as the lowest value estimated for the median lethal concentration (LC50). The decreasing rank of toxicity was Cry1F, Cry2Aa, and Cry1Ac. Foliage of dual-toxin Bt cotton varieties (Cry1Ac + Cry1F and Cry1Ab + Cry2Ae) caused higher larval mortality than Cry1Ac-expressing cotton. Black armyworms showed reduced larval weight when growing on the Cry1Ac-treated diet, yet they reached adulthood and produced offspring. Interestingly, these larvae were grown on the control diet and showed reduced weight gain associated with the toxin exposure of the previous generation, indicating a parental effect of the exposure to Cy1Ac. The reduced larval weight was recovered in later instars, and there was no significant change in the population fitness of the parental armyworms or their offspring. To our knowledge, this is the first study documenting the parental effects of Bt toxins in insects. These results advance our understanding of potential responses of nontarget species when exposed to Bt toxins and contribute to design pest management programs for armyworms and other nontarget lepidopteran species exposed to Bt crops.
Collapse
Affiliation(s)
- Marcelo M Rabelo
- Department of Entomology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
- West Florida Research and Education Center, Department of Entomology and Nematology, University of Florida, Jay, FL
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - João Marcus L Matos
- Department of Entomology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Silvana M Orozco-Restrepo
- Department of Entomology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Silvana V Paula-Moraes
- Department of Entomology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
- West Florida Research and Education Center, Department of Entomology and Nematology, University of Florida, Jay, FL
| | - Eliseu José G Pereira
- Department of Entomology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| |
Collapse
|