@article{dively_kuhar_taylor_doughty_holmstrom_gilrein_nault_ingerson-mahar_huseth_reisig_et al._2023, title={Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance}, volume={14}, ISSN={2075-4450}, url={http://dx.doi.org/10.3390/insects14070577}, DOI={10.3390/insects14070577}, abstractNote={Simple Summary Corn and cotton that produce insecticidal toxins derived from Bacillus thuringiensis (Bt) are widely adopted in the United States to control corn earworm/cotton bollworm, Helicoverpa zea (Boddie), which has resulted in major benefits to growers and the general public. However, resistance evolution in H. zea populations has become a major threat to the sustainability of these crops. Bt sweet corn producing the same toxins as Bt field corn is more attractive to H. zea than field corn and, thus, can function as a sentinel plant to detect early stages of resistance. As part of an existing sentinel monitoring network, this study evaluated changes in H. zea resistance during 2020–2022 by estimating the phenotypic and resistance allele frequencies for toxins in sentinel Bt corn. Abstract Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020–2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa.}, number={7}, journal={Insects}, publisher={MDPI AG}, author={Dively, Galen P. and Kuhar, Tom P. and Taylor, Sally V. and Doughty, Helene and Holmstrom, Kristian and Gilrein, Daniel O. and Nault, Brian A. and Ingerson-Mahar, Joseph and Huseth, Anders and Reisig, Dominic and et al.}, year={2023}, month={Jun}, pages={577} }
 @article{hudson_alford_bilbo_boyle_doughty_kuhar_lopez_mcintyre_stawara_walgenbach_et al._2023, title={Living mulches reduce natural enemies when combined with frequent pesticide applications}, volume={357}, ISSN={["1873-2305"]}, DOI={10.1016/j.agee.2023.108680}, abstractNote={Agricultural intensification with frequent pesticide applications often diminishes biological control services delivered by beneficial insects. However, re-integrating diverse and structurally complex non-crop habitat may mitigate negative effects by providing refugia to natural enemies, enabling rapid recolonization of pesticide-treated crops. This study examines the compatibility of chemical control with non-crop habitat management by manipulating pesticide treatments and living mulches between rows of zucchini crops in four replicated experiments across the Southeastern United States. The hypothesis was that living mulches and pesticide applications would each negatively impact pests and have interactive effects on predatory insects, with negative pesticide effects being attenuated in plots with untreated living mulches serving as refugia for predators between crop rows. Instead, combining living mulches with pesticide applications reduced natural enemy densities, relative to bare plots. Pesticide applications had no effect on spotted and striped cucumber beetle pests, while living mulches directly reduced them by 25%. Conversely, pesticide applications reduced squash bug pressure by 50%, while living mulches had no effect. Although crops were grown in plastic mulch to protect them from competition, living mulches reduced zucchini yields by 54% at sites where living mulches were less-managed. Alternatively, living mulches had more neutral effects on yields at sites where mulches were mowed monthly, suggesting that living mulches require management to minimize competition with crops. These results suggest that the grass-dominated living mulches tested in this study did little to harmonize chemical and biological control. While non-crop plant diversity has clear benefits for natural pest suppression in many systems, these benefits cannot be generalized across all plant and insect taxa. Future efforts to fine-tune management of non-crop habitat within fields will be strengthened by consideration of traits of key pests and their specific responses to both pesticide applications and plant diversity.}, journal={AGRICULTURE ECOSYSTEMS & ENVIRONMENT}, author={Hudson, T. Blake and Alford, Adam M. and Bilbo, Tom R. and Boyle, Sean C. and Doughty, Helene B. and Kuhar, Thomas P. and Lopez, Lorena and McIntyre, Kelly C. and Stawara, Allison K. and Walgenbach, James F. and et al.}, year={2023}, month={Nov} }
 @article{bilbo_kennedy_walgenbach_2023, title={Western flower thrips (Frankliniella occidentalis) field resistance to spinetoram in North Carolina}, volume={165}, ISSN={["1873-6904"]}, url={https://doi.org/10.1016/j.cropro.2022.106168}, DOI={10.1016/j.cropro.2022.106168}, abstractNote={The western flower thrips (Frankliniella occidentalis (Pergande), “WFT”) is an invasive pest of fruit and vegetable crops throughout the southeastern United States. The spinosyn insecticides spinetoram (Radiant®) and spinosad (SpintTor®) have been used to manage WFT in NC tomatoes for >20 years. Control failures with spinetoram were reported by growers in the Piedmont of NC beginning in the mid-2010s. The goal of this study was to investigate the development of WFT resistance to Radiant in tomato fields in Piedmont and mountain production regions of NC. In 2019 and 2020, WFT populations were collected from staked-tomato fields and subjected to dose-response bioassays to estimate lethal concentration values (LC50) for comparison with a susceptible laboratory colony. In 2021, additional populations were collected from each region and evaluated using diagnostic doses of Radiant (100 and 1000 PPM v/v). Results from dose-response bioassays revealed resistance ratios (RR50) as high as 1487.7 in populations from Rowan County in the Piedmont. Additional diagnostic dose bioassays conducted in 2021 further supported reduced susceptibility to Radiant in all five tested populations. Populations from Henderson County in the mountains were much more susceptible than those in the Piedmont, with resistance rations of only 1.18 and 26.15. Bioassays with a single highly resistant colony over 17 generations found survival to remain mostly constant. These results provide evidence supporting the development of practical, field-evolved resistance to spinetoram in WFT in NC, and the need for improved insecticide resistance management strategies.}, journal={CROP PROTECTION}, author={Bilbo, Tom R. and Kennedy, George G. and Walgenbach, James F.}, year={2023}, month={Mar} }
 @article{bilbo_owens_golec_walgenbach_2022, title={Impact of insecticide programs on pests, the predatory mite Phytoseiulus persimilis, and staked tomato profitability}, ISSN={["1526-4998"]}, DOI={10.1002/ps.6866}, abstractNote={BACKGROUND
Various insecticides are available to manage diverse pest complexes in commercial vegetable production, but knowledge gaps exist regarding their overall performance in pest suppression, profitability, and compatibility with biological control. We conducted trials in staked tomatoes in western North Carolina in 2017-2018 to compare how different insecticide programs managed key pests and their interactions with Phytoseiulus persimilis Athias-Henriot, a predator of the twospotted spider mite (TSSM, Tetranychus urticae Koch). Treatments compared no insecticides to broad-spectrum ('hard') foliar applications, selective ('soft') foliar applications, and to chemigation of selective systemic insecticides. Treatment efficacy was based on pest control, net profitability, and Environmental Impact Quotient (EIQ) ratings comparing environmental and human health risks.


RESULTS
All programs similarly suppressed aphids, while flower thrips and flea beetle populations were low and unaffected by program. Only the 'hard' foliar program suppressed TSSM (including P. persimilis), which quickly rebounded. This program inhibited biological control, and eventual TSSM suppression was likely caused by P. persimilis immigrating from nearby plots. All programs were generally equivalent in reducing fruit damage. Net profits were similar among insecticide programs, which were significantly greater than in untreated plots. Yield and profit trends were similar both years, but impacted by record flooding in 2018.


CONCLUSION
Safer and more selective chemigation and 'soft' foliar programs were as effective and economical as the 'hard' foliar program, while also conserving biological control. These results support existing research demonstrating that improved insecticide use can be integrated with biological control for more profitable and environmentally sustainable vegetable production.}, journal={PEST MANAGEMENT SCIENCE}, author={Bilbo, Tom R. and Owens, David R. and Golec, Julian R. and Walgenbach, James F.}, year={2022}, month={Mar} }
 @article{walgenbach_bilbo_tussey_ogburn_2021, title={Comparison of chemigationversusfoliar insecticide use: management of lepidopteran larvae and stink bugs in North Carolina field tomatoes with environmental and farmworker benefits}, volume={77}, ISSN={["1526-4998"]}, DOI={10.1002/ps.6074}, abstractNote={BACKGROUND
Commercial vegetable production in the United States of America (USA) often relies on foliar insecticide sprays for managing key insect pests. However, foliar applications of insecticides have a number of drawbacks to the health of consumers, farmworkers, and the environment. Drip chemigation is the application of pesticides to the soil through trickle (drip) irrigation systems, and can overcome a number of the drawbacks typical of foliar insecticide applications.


RESULTS
We conducted a two-year study in five commercial fields of staked tomatoes in western North Carolina to compare the efficacy, economics, and environmental impact of drip chemigation versus foliar sprays. Drip chemigation significantly reduced insecticide inputs, utilized more selective and environmentally compatible insecticides, and reduced the time lost to reentry intervals, while maintaining comparable efficacy and economic returns.


CONCLUSIONS
Drip chemigation was an effective tool for managing key insect pests, provided a broad range of human and environmental health benefits, and will likely become increasingly cost effective in the future as insecticide patents expire and more insecticide options become available. This article is protected by copyright. All rights reserved.}, number={2}, journal={PEST MANAGEMENT SCIENCE}, author={Walgenbach, James F. and Bilbo, Tom R. and Tussey, Dylan A. and Ogburn, Emily C.}, year={2021}, month={Feb}, pages={758–765} }
 @article{bilbo_walgenbach_2020, title={Compatibility of Bifenazate and Phytoseiulus persimilis for Management of Twospotted Spider Mites in North Carolina Staked Tomatoes}, volume={113}, ISSN={["1938-291X"]}, DOI={10.1093/jee/toaa159}, abstractNote={Abstract The twospotted spider mite (TSSM, Tetranychus urticae Koch) is a key pest of tomatoes (Solanum lycopersicon L. [Solanales: Solanaceae]) in North Carolina, and its management has relied principally on synthetic acaricides. Augmentative biological control of TSSM is a commonplace and effective management strategy in greenhouses worldwide, but in field-grown vegetable crops biocontrol of TSSM is poorly developed. We conducted small-plot field experiments in 2016 and 2019 to test the ability of the predatory mite, Phytoseiulus persimilis Athias-Henriot, to establish, disperse, and reduce TSSM in staked tomatoes, as well as test their compatibility with a commonly used reduced-risk acaricide, bifenazate (Acramite). Across both years, the most effective treatment for reducing TSSM was the combination of P. persimilis + Acramite. Phytoseiulus persimilis successfully established both years, but its population growth and dispersal were greater in 2016 than 2019. Acramite alone significantly reduced TSSM pressure in 2019 and P. persimilis alone did not reduce TSSM pressure below the control in either year. However, results in 2016 were influenced by the eventual dispersal of P. persimilis into all experimental plots, despite efforts to hinder their movement with corn barriers. Results in 2019 were influenced by the late-season invasion of TSSM into the trial, which delayed P. persimilis releases and influenced their establishment and growth. This study is the first to demonstrate the utility and limitations of P. persimilis in staked field tomatoes, which is a promising option for growers to manage TSSM in tomatoes in the southeast United States.}, number={5}, journal={JOURNAL OF ECONOMIC ENTOMOLOGY}, author={Bilbo, Tom R. and Walgenbach, James F.}, year={2020}, month={Oct}, pages={2096–2103} }
 @article{reay-jones_bilbo_reisig_2020, title={Decline in Sublethal Effects of Bt Corn on Corn Earworm (Lepidoptera: Noctuidae) Linked to Increasing Levels of Resistance}, volume={113}, ISSN={0022-0493 1938-291X}, url={http://dx.doi.org/10.1093/jee/toaa163}, DOI={10.1093/jee/toaa163}, abstractNote={As part of an ongoing longitudinal study in North and South Carolina, this study reports the recovery of Helicoverpa zea (Boddie) pupae in field trials with genetically engineered corn, Zea mays L., hybrids that produce insecticidal toxins from Bacillus thuringiensis (Bt) in 2017-2019. In total, 10,400 corn ears were collected, which led to 3,927 H. zea pupae (2,215 in South Carolina and 1,712 in North Carolina). Late-planted corn led to a 3.39-fold increase in recovery of pupae compared to early-planted corn. Bt corn expressing Cry1F + Cry1Ab and Cry1A.105 + Cry2Ab2 had 1.67-fold and 2.51-fold fewer pupae than non-Bt near-isolines, respectively. Only six pupae were recovered from the hybrid expressing Cry1F + Cry1Ab + Vip3Aa20. Averaged across trials, Bt corn expressing either Cry1A.105 + Cry2Ab2 or Cry1F + Cry1Ab significantly reduced pupal weight compared to non-Bt near-isolines in North and South Carolina. Combining our data with a previous study at the same locations (Bilbo et al. 2018), reduction in pupal weight between Bt and non-Bt near-isolines significantly declined from 2014 to 2019 for Cry1Ab + Cry1F in North and South Carolina. This decline in levels of a sublethal effect of Bt corn expressing Cry1Ab + Cry1F on H. zea at both locations is likely correlated with resistance development.}, number={5}, journal={Journal of Economic Entomology}, publisher={Oxford University Press (OUP)}, author={Reay-Jones, Francis P F and Bilbo, Thomas R and Reisig, Dominic D}, editor={Gassmann, AaronEditor}, year={2020}, month={Aug}, pages={2241–2249} }
 @article{bilbo_reay-jones_reisig_greene_2019, title={Susceptibility of Corn Earworm (Lepidoptera: Noctuidae) to Cry1A.105 and Cry2Ab2 in North and South Carolina}, volume={112}, ISSN={0022-0493 1938-291X}, url={http://dx.doi.org/10.1093/jee/toz062}, DOI={10.1093/jee/toz062}, abstractNote={Abstract The corn earworm, Helicoverpa zea (Boddie), is managed in corn and cotton in the United States primarily using transgenic cultivars that produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). However, increasing reports of resistance to one or more Bt proteins threaten the continued efficacy of Bt traits. To better understand the development of resistance of H. zea to Bt corn and cotton in the southeastern United States, we monitored for resistance to Cry1A.105 and Cry2Ab2 among 22 field populations of H. zea collected in non-Bt and Bt corn expressing Cry1A.105 + Cry2Ab2 during 2017 and 2018. Colonies were established in the laboratory and progeny were screened in diet-overlay bioassays to purified Cry1A.105 and Cry2Ab2 proteins. Compared with two susceptible laboratory colonies, all 14 field colonies tested with Cry1A.105 were highly resistant, with resistance ratios (RRs) ranging from 13.5 to >4,000. For Cry2Ab2, 19 colonies were tested and RRs ranged from 0.26 to 33.7. Field populations were significantly more susceptible to Cry2Ab2 than Cry1A.105. We documented variability in F0 and F1 pupal weight and developmental rates of natural populations of H. zea, but observed no significant correlation with susceptibility to either Cry1A.105 or Cry2Ab2. Our results expand on the recent reports of H. zea resistance to Cry1A and Cry2A proteins and will aid in the design and deployment of future pyramided crops in the United States.}, number={4}, journal={Journal of Economic Entomology}, publisher={Oxford University Press (OUP)}, author={Bilbo, Tom R and Reay-Jones, Francis P F and Reisig, Dominic D and Greene, Jeremy K}, year={2019}, month={Mar}, pages={1845–1857} }