Progress 09/01/18 to 08/31/23
Outputs
Target Audience: Target audience of this project includes conventional and organic fruit and vegetable growers, county-, area- and state-wide extension agents and specialists, crop consultants, agricultural crop protection industry personnel, integrated pest management scientists and practitioners, and the general public. Changes/Problems:In the final year (no cost extension) of this project most remaining efforts focused on finishing Extension and outreach activities. In April 2023, PD Dr. JC Chong left Clemson University and the project was transferred to assistant professor Dr. Tom Bilbo (previously a postdoc on this project under Dr. Walgenbach at NCSU). What opportunities for training and professional development has the project provided?Five post-doctoral research associates (Drs. Tom Bilbo, Lorena Lopez, Deepak Shrestha, Gunn Gill, and Hamish McKirdy) participated and received training from their respective mentors at NCSU, CU, and UF on developing and executing field research projects, data management, and presentations at scientific meetings, grower field days and extension meetings. They also have had opportunities to meet experts, fellow scientists, faculty and students, and expand their knowledge and skills in the field. New relationships between research teams and organic growers in each state were initiated and cultivated as part of the natural enemy survey conducted in Obj. 2.1, which will lead to future collaborations and grower involvement. All post-doctoral associates who participated in this project have successfully secured full-time employment in academic, governmental and industry settings. Two graduate students (at UGA and CU) participated in this project, and an agricultural economy graduate student (at CU) worked on assessing the economic benefits of this project part-time (Levinson et al. 2022). These students were trained on proper experimental design, data collection and data management. Numerous undergraduate students and technicians also received training on conducting field trials in the area of applied agricultural entomology as part of this project. How have the results been disseminated to communities of interest?The research and extension teams utilize mainly direct interactions with and presentations to stakeholders at grower meetings and field days, as well as the project website and webinars hosted by eOrganic, as a means of disseminating project results to communities of interest. The project website has delivered biological control information and the project results in the form of webinars, videos, and other online publications such as NCSU's insecticide compatibility table for predatory mites. The experience and training from this project have resulted in many other forms of dissemination, such as postdoc Lopez updating the 'Beneficial Insects' section in the widely used Southeastern US Vegetable Crop Handbook (2024). Peer-reviewed publications have also been submitted or published, and scientific presentations have been provided at scientific meetings for the scientific audience. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
North Carolina State University (NCSU) research team (Walgenbach and Bilbo) successfully developed throughout the duration of this project a management strategy for spider mites in staked tomatoes using the predatory mite Phytoseiulus persimilis. Small-plot and large scale on-farm studies demonstrated that early, inoculative releases of P. persimilis can successfully establish and disperse throughout fields to suppress spider mites (Obj. 1.1). An economical and grower-friendly rearing system for P. persimilis on tomatoes was also developed (Obj. 1.4, 1.7) and these successes have garnered significant interest from growers and stakeholders throughout the eastern US (based on feedback during several regional grower meetings, field days, webinars, and conferences, Obj. 3). Additional replicated on-farm field studies comparing the efficacy of tomato-adapted vs. bean-adapted P. persimilis did demonstrate that tomato-adapted performed better but that both significantly suppressed spider mites (Obj. 1.3). It was also determined that the acaricide bifenazate is compatible with P. persimilis (Bilbo and Walgenbach 2020) and that 'soft' foliar and chemigated insecticide programs resulted in similar net profits to 'hard' foliar programs but with the benefit of conserving biological control (Bilbo et al. 2022). Lab and field studies demonstrated that Amblyseius swirskii could not establish on tomato (Obj.1.3), leaving biocontrol options limited for western flower thrips (WFT) in this crop. WFT field-evolved resistance to spinosyns was documented (Bilbo et al. 2023) and preliminary data on management with OMRI-approved products, including endophytic Beauvaria bassiana (JABB), was collected in the last year. JABB was applied as a soil drench to tomato seedlings at 2 and 5 weeks after seeding and plants were infested with adult western flower thrips. An additional study compared JBB to other OMRI-approved and conventional insecticides. In both studies JABB resulted in numerical but not significant reductions in thrips numbers. At this time OMRI-insecticides appear limited in their ability to manage WFT in tomatoes, and other cultural and biological control tactics should be explored. The Clemson University research team (Chong, Gill, Sikora, Brown) completed a study to evaluate the compatibility of seven common natural enemy species with nine OMRI-listed insecticides and fungicides (Obj 1.5, 2.1, 2.2). Data demonstrated that, although some insecticides had significant negative impacts on natural enemies' survival, other insecticides had mixed results. Recommendations can be made based on data collected in this study to avoid using pyrethrins and spinosad; azadirachtin should be used with cautions depending on natural enemy species, and B. thuringiensis is compatible with all natural enemy species. Residue of non-copper fungicides are generally compatible with the predatory mites P. persimilis and N. californicus, but cuprous fungicides had mixed results among different species. This research and the field studies conducted in NC have highlighted for growers the importance of proper insecticide timing and product selection, even among OMRI-approved products, which are often perceived as being equally innocuous towards beneficial species. The University of Florida (UF) research team (Liburd, Shrestha, Lopez, and Marucci) conducted a series of studies to improve the augmentation and conservation of predatory natural enemies for management of whiteflies. Experiments evaluated release methods and timing of A. swirskii to manage whiteflies in an open-field squash production systems (Obj. 1.2). All release methods resulted in successful establishment of A. swirskii which resulted in significant suppression of whiteflies, and early releases (4 wks or less from planting) may be more effective, as seen with P. persimilis in tomatoes in NC. Whiteflies showed a preference among squash cultivars and 'Eight Ball' was the least preferred. A significantly higher number of virus infected plants were observed on control than other release methods, with 'Eight Ball' having a lower number of infected plants than the other two cultivars. The UF team investigated potential for intraguild predation of A. swirskii eggs, nymphs and adults by Orius insidiosus and Geocoris punctipes in the presence of prey whiteflies and thrips (Obj. 2.3). Results from this study suggest that low prey densities may result in higher intraguild predation on predatory mites but clear patterns of interactions among the three predator species did not emerge. Another study evaluated interactions between A. swirskii and the endemic predator Delphastus catalinae on whitefly behavior and oviposition. It was found that D. catalinae released alone or in combination with A. swirskii reduced whitefly oviposition rate, highlighting the benefit and importance of indirect (e.g. non-consumptive effects) of natural enemies on pest species. To our knowledge, this is the first attempt to evaluate intraguild interactions between species from different arthropod classes (Insecta and Arachnida) and the methodology for experimentation is still in development. Future research should include additional ecological factors when testing the effects of intraguild interactions. The University of Georgia research team (Srinivasan, Dutta and Coolong) conducted a series of whitefly and thrips trials in tomato and squash involving multiple viruses (Obj. 1.6) to determine how to combine host plant resistance with predatory mites. Though in most instances, one would expect synergism between the two tactics adopted, increased vector dispersal due to the presence of predatory mites and subsequent enhanced virus spread is a concern. In tomatoes, predatory mites were rarely recovered and predator treatments did not affect thrips densities, but there was a significant cultivar effect on thrips densities. These results support those found in NC that A. swirskii cannot be relied on to manage thrips in tomatoes, but thrips preferences for cultivars suggests cultural control leveraging preferences may have potential. A tomato cultivar effect was also observed for whitefly adults and nymphs, and the location of predatory mite release on plants had some significant effects on whitefly densities but predatory mite counts were extremely low throughout the trial. There was no significant effect of treatment, variety, or date on predatory mites. Trials in squash showed that predatory mites significantly reduce whitefly adults and, in some weeks, eggs and nymphs. While predatory mites can suppress whiteflies in squash, they did not reduce the high incidence of CuLCrV. To improve stakeholder knowledge of biological control in tomatoes and cucurbits, a diversity of outreach activities have taken place (Obj. 3). Researchers in each state have presented this project and its findings and recommendations at numerous grower field days, grower/commodity meetings, scientific conferences, and webinars. PD Bilbo has personally encountered significant interest from agents and growers throughout the eastern US on using P. persimilis in field and greenhouse tomatoes and he has provided guidance to those stakeholders on trying developed approaches in different regions (e.g. Michigan, New York). The Oregon State team (Formiga) created and hosted a project website (https://eorganic.info/biocontrol), a published webpage of overall project findings (including a discussion of economic considerations--Obj. 1.7), and eight webinars. The webinars garnered interest from stakeholders throughout the US resulting in invitations for team members to speak on this project at grower meetings outside the southeastern US (e.g. Bilbo, Great Lakes Fruit & Veg Expo 2023). The four most recent webinars hosts in April and May 2023 had 156 attendees and 982 online views (as of 11/15/23).
Publications
- Type:
Websites
Status:
Published
Year Published:
2023
Citation:
Project Summary: "Developing and Implementing Biological Control Tactics for Key Insect Pests in the Southeastern United States: Summary of Findings from a NIFA OREI Project." December 2023. https://eorganic.org/node/35765
- Type:
Other
Status:
Published
Year Published:
2023
Citation:
Webinar: How to manage spider mites in tomatoes with predatory mites. May 24, 2023. TR Bilbo (Clemson University) and JF Walgenbach (NC State University). Registered 127, Attended 54, 382 views of recording on Youtube (as of 11/15/23). https://eorganic.org/node/35704
- Type:
Other
Status:
Published
Year Published:
2023
Citation:
Webinar: Compatibility of selected OMRI-listed insecticides and fungicides with biological control. April 13, 2023. JC Chong (Clemson University). Registered 129, Attended 61, 274 views of recording on Youtube (as of 11/15/23). https://eorganic.org/node/35682
- Type:
Other
Status:
Published
Year Published:
2023
Citation:
Webinar: Effects of the predatory mite, Amblyseius swirskii and its biproducts on whitefly Bemisia tabaci populations. May 11, 2023. OE Liburd (University of Florida). Registered 40, Attended 11, 160 views of recording on Youtube (as of 11/15/23). https://eorganic.org/node/35689
- Type:
Other
Status:
Published
Year Published:
2023
Citation:
Webinar: Predatory mite for the management of insect-transmitted viruses in vegetable production. May 2, 2023. R Srinivasan (University of Georgia). Registered 74, Attended 30, 166 views of recording on Youtube (as of 11/15/23). https://eorganic.org/node/35698
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Grower meeting: Biological control of spider mites in tomatoes using predatory mites by TR Bilbo (Clemson University) and JF Walgenbach (NC State University). Great Lakes Fruit and Vegetable Expo. Grand Rapids, Michigan December 6, 2023.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Commodity meeting: "Insect management update in vegetables: brassicas, cucurbits, and tomatoes by TR Bilbo (Clemson University). Pee Dee vegetable pre-plant meeting, Florence, SC, February 28, 2023.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Symposium Poster: Compatibility of OMRI-listed insecticides and fungicides with selected biological control agents by JC Chong and D Sikora (Clemson University). Entomological Society of America annual meeting, National Harbor, MD, November 2023.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Grower meeting (virtual): Bilbo TR. January 2022. How to manage thrips and mites in tomatoes and peppers. Tomato/Pepper Statewide Meeting (virtual)
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Conference Paper: Biological control of spider mites in strawberries and tomatoes using Phytoseiulus persimilis by TR Bilbo (Clemson University) and JF Walgenbach (NC State University). Entomological Society of America annual meeting, National Harbor, MD, November 2023.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Bilbo TR, Owens D, Golec JR, and JF Walgenbach. 2022. Impact of insecticide programs on pests, the predatory mite Phytoseiulus persimilis, and staked tomato profitability. Pest Management Science 78: 2390-2397. *conducted and published as part of Bilbo postdoc at NCSU
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Grower meeting: "Thrips management in tomatoes" by JF Walgenbach. North Carolina Tomato Growers Association winter vegetable conference, February 2023, Asheville, NC.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Bilbo, TR, GG Kennedy and JF Walgenbach. 2023. Western flower thrips resistance to spinetoram in North Carolina. Crop Protect. 165: 106168. doi:10.1016/j.cropro.2022.106168
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Lopez, L. and O. E. Liburd. 2022. Can the introduction of companion plants increase biological control services of key pests in organic squash? Entomologia Experimentalis et Applicata. https://doi.org/10.1111/eea.13147
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Bilbo TR and JF Walgenbach. 2022. Western flower thrips in North Carolina agroecosystems: Changing pest status and resistance to spinetoram. Entomological Society of America Southeastern Branch, San Juan, PR, March 2022
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Grower meeting: Bilbo, TR. January 2023. Cucurbit IPM: Managing pests and enhancing beneficials. Cucurbit pre-plant grower workshop (Clemson EREC, Blackville, SC).
|
Progress 09/01/21 to 08/31/22
Outputs
Target Audience:Target audience of this project includes conventional and organic fruit and vegetable growers, county-, area- and state-wide extension agents and specialists, crop consultants, agricultural crop protection industry personnel, integrated pest management scientists and practitioners, and the general public. Changes/Problems:The main concerns with this year's study on predator's impact on virus incidence were extremely low virus incidence, and poor recovery of the predatory mites while sampling. Virus pressure issues could be addressed by conducting supplementary experiments with microcosms. This project team continues to face difficulties in receiving approval and scheduling biological control and an organic production focused workshop atSoutheast Fruits and Vegetables Conference and other regional events. This team will continue to work with event organizers at scheduling but will not focus our efforts on these events. Instead, efforts will be expanded to provide other educational opportunities, such as webinars through eOrganic or video posting via eOrganic or state extension services. What opportunities for training and professional development has the project provided?Three post-doctoral research associates (Drs. Thomas Bilbo, Gunn Gill and Lorena Lopez) completed their training under this project and havesecured faculty or permanent positions at universities and private companies. These researchers are able to put their skills learnedunder this project, such as developing and executing field research projects, data management, and presentations at scientific meetings, grower field days and extension meetings, to use in their new positions. A new post-doctoral fellow (Hamish McKirdy) has been recruited at NCSU to complete this project.Three graduate students (at UGA and CU) are participating in this project. An agricultural economy graduate student (at CU) has successfully completed his program of assessing the economic benefits of this project. They were trained on proper experimental design, data collection and data management. Undergraduate students and technicians also received training on conducting field trials in the area of applied agricultural entomology. How have the results been disseminated to communities of interest?The research and extension teams utilize mainly direct interactions with and presentations to stakeholders at grower meetings and field days, as well as the projectwebsite and webinars hosted by eOrganic, as means of disseminating project results to communities of interest. The project website has delivered biological control information and the project results in the form of webinars and videos.Peer-reviewed publications have also been submitted or published, and scientific presentations havebeen provided at scientific meetings for the scientific audience. What do you plan to do during the next reporting period to accomplish the goals?Plans have been made for the next reporting period to complete several on-going experiments. The research team at NCSU will continue their experiments to identify factors important to the dispersal of predatory mite populations and develop a grower friendly rearing system for crop-adapted strains of predatory mites, particularlyA. swirskii(Objective 1.3 and 1.4). The UGA team will continue its experiments on determining how predatory mite releases may impact whiteflies and thrips populations, as well as viral incidences associated with these important pests, in tomato production (Objective 1.6). The CU team will complete the identification of natural enemies found in surveys in the organic fields in FL, NC, GA and SC (Objective 2.1).Major effort will focus on developing additional education materials and opportunities for organic vegetable growers. Due to the success of the webinar series developed by team members and delivered via eOrganic in 2021, the team will develop additional webinars for delivery through eOrganic. Also, videos on identifying pests and natural enemies and practicing biological controlwill also be prepared with assistance from state extension services and will be delivered through eOrganic and state extension services.
Impacts
What was accomplished under these goals?
North Carolina State University (NCSU) research team (Walgenbach and Bilbo)has conducted a study on commercial tomato farms to compare two strains ofP. persimilisfor reducing TSSM populations and to characterize predator dispersal (Objective 1.3). The experiment in 2020 indicated that the tomato-adapted strain dispersed quickly throughout the field. In contrast to the 2020 experiment, the 2021 experiment reportedlimited dispersal beyond about 25 meters. The reason for this divergence from previous studies is unknown, but this will be repeated in 2023.Greenhouse experiments are currently underway to develop a grower-friendly rearing system for the predatory miteAmblysieus swirskiifor release on commercial farms (Objective 1.4). While theP. persimilisrearing system has been successfully developed for tomatoes,A. swirskiihas been proven more difficult to establish on tomatoes. The research team at Clemson University (Chong, Sikora and Brown) has completed a study to evaluate the compatibility of seven natural enemy species with nine OMRI-listed insecticides and fungicides (Objective 1.5 and 2.2). Data demonstrated that, although some insecticides had significant negative impacts on natural enemies' survival, other insecticides had mixed results. Recommendations can be made based on data collected in this study to avoid using pyrethrins and spinosad; azadirachtin should be used with cautions depending on natural enemy species, andB. thuringiensisis compatible with all natural enemy species. Residue of non-copper fungicides are generally compatible withP. persimilisandN. californicus,but cuprous fungicides had mixed results among different species.The NCSU team conducted a field experiment to investigate potentialresistance of western flower thrips to the insecticide spinetoram, an insecticide used in vegetables, as part of field evaluation of insecticide compatibility with biological control (Objective 2.2). Dose-response study conducted under this project showed that resistance to spinetoram is not widespread; it is more common in the Piedmont than Mountain regions of North Carolina. Continuing assay for resistance among thrips populations in organic farms will continue in 2023. The research team at the University of Georgia (UGA) (Srinivasan, Dutta and Coolong) conducted two field trials to evaluate the impact of predatory mite release methods on whiteflies and TYLCV incidence in a TYLCV-susceptible(Rosa Sicilian) and a resistant cultivar (Skyway) of tomato, and a single CuLCrV-susceptible cultivar of squash (Objective 1.6). Tomato and squash plants received noA. swirskii, or predatory mites were released at the base of the plant, on the foliage or via sachets.On tomatoes and squashes, whitefly nymph and egg abundances did not vary by cultivar or by mite release. These results indicated that neither the tomato cultivar nor the placement of predatory mites affected whitefly abundance. Incidences of CuLCrV and criniviruses, such as CYSDV and CCYV, were detected in the squash fields, but no significant difference in incidence and severity were detected. As noted in the study in North Carolina, it is likely thatA. swirskiiis not well suited for releases on tomatoes and that the placement of predatory mites did not achieve suppression of whitefly population or virus incidence. Field surveys of thrips and whitefly natural enemies (Objective 2.1) in organic fields have been completed. Samples are being processed and identified by the research team at Clemson University (Chong). Preliminary results suggested that few natural enemies were present in the collected samples. The most common natural enemies were spiders, ground beetles, and predatory mites in the family Phytoseiidae. The UF research team (Liburd and Lopez)conducted an experiment toexamineinteractions between an endemic predator,Delphastus catalinae, and augmentative releases ofA. swirskiito determine its effect on whitefly's behavior and oviposition (Objective 2.3).Approximately six female whiteflies were released into a container harboring two squash leaves andi) 2D. catalinae,ii) 2A.swirskii,iii) 2D. catalinae+ 2A. swirskii,or without predator (control). The number of whitefly eggs, nymphs and adults were counted.Adult whiteflies showed different oviposition capacities due to the presence or absence of one or more predator species. The number of eggs laid in the presence ofD. catalinaeorA. swirskii+D. catalinaewas lower than the control. The numbers of eggs in control andA. swirskiitreatments were more than 2.7X higher compared with the other two treatments. We found thatD. catalinaereleased alone or in combination withA. swirskiiinduces a significant change in the oviposition rate that reflects in the number ofwhiteflyadults. The economic team from Clemson University (Lamie and Levinson) refined and implemented a survey of producers for their perception of IPM and biological control. This survey yielded useful information about how producers respond to and use IPM educational information. Information about the IPM strategies and the estimation of the potential economic benefits and costs involved has also been collected. At this time, it is difficult to determine with precision the actual economic benefits and costs associated with the field trials. However, as more observations on yield impacts of the IPM strategies are made, we expect to have a clearer picture. Preliminarily, it was observed that more labor and increased management finesse seems to be required for IPM strategies to be effectively deployed. Overall insect control costs would be substantially reduced if deployed appropriately. With input costs rising rapidly, finding ways to be effective managers of biological systems is of utmost importance. One of the most interesting insights gained from these interviews is that the location of the field and its proximity to other lands and how they are managed can have likely large impacts on the in-field production economics. For instance, as beneficial insects are introduced into a field and their population grows over time, they become more effective in their duty of reducing the pest species. If these beneficials are allowed to move to compatible environments nearby for further reproduction or overwintering, then the costs of acquiring or growing a sufficient population of beneficials is substantially reduced. Thus, the management practices of adjacent or regional "other" landowners are quite important. Further, if a new producer is intent on using such IPM strategies, and they have not yet acquired land, then one of the factors involved in choosing their land for cultivation ought to be adjacent land uses. For existing (and new) producers, attention ought to be paid to the informal relationships and customs that allow them to potentially influence these adjacent activities along with attention to relevant regulations. Efforts to improve stakeholder knowledge of biological control in tomatoes and cucurbits are also underway (Objective 3). Through the eOrganic webinar series, the project team provided four webinars for stakeholders. The webinars covers topics on biological control options available, spider mite biocontrol in tomato, whitefly biocontrol in squash, and the relationship between biocontrol and virus transmission. 385 persons attended the webinars and the recordings of the webinars (posted on eOrganic website) were viewed 1876 times up to mid-August 2022. Results and related topics (e.g., educational material and field identification techniques) have also been shared at field days (such as the NCSU State Virtual Tomato Field Day, NCTGA Vegetable Field Day, PDREC Field Day) with more than 300 contacts. A Stakeholders Advisory Panel meeting was conducted in November 2021, where stakeholders were updated on the project progress.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Bilbo, T.R., D. Owens, J. R. Golec, and J.F. Walgenbach. Impact of insecticide programs on pests, the predatory mite Phytoseiulus persimilis, and staked tomato profitability. Pest Management Science 78: 2390-2397. https://doi.org/10.1002/ps.6866
- Type:
Journal Articles
Status:
Under Review
Year Published:
2022
Citation:
Bilbo, TR, GG Kennedy, and JF Walgenbach. Western flower thrips field resistance to spinetoram in North Carolina. Crop Protect. Submitted in review.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Bilbo, TR, and JF Walgenbach.Optimizing biological control of Tetranychus urticae with the predatory mite Phytoseiulus persimilis in staked tomato systems. Annual Meeting of the Entomological Society of America, Denver, CO.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Liburd O. E. and L. Lopez 2021. Biological control in vegetables with a focus on squash. Annual Meeting of the Entomological Society of America, Denver, CO.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2022
Citation:
Levinson, Lamie, Vassalos, Eck, Chong, Jones. An Exploration of Learning and Teaching Methods in Agricultural Extension. Journal of Extension. Submitted in review.
- Type:
Websites
Status:
Published
Year Published:
2022
Citation:
Biocontrol Tactics for Key Vegetable Insect Pests in the Southern U.S. Website. Available at https://eorganic.info/biocontrol
- Type:
Other
Status:
Published
Year Published:
2021
Citation:
Webinar: Biological Control Options in Vegetables, February 3, 2021, by Juang Chong and Gunn Gill, Clemson University. Registered 213, Attended 130, 738 views of recording.
- Type:
Other
Status:
Published
Year Published:
2021
Citation:
Webinar: Insect-vectored Viruses and their Management in Vegetables, February 10, 2021, by Rajagopalbabu Srinivasan, University of Georgia. Registered 166, Attended 94, 331 views of recording.
- Type:
Other
Status:
Published
Year Published:
2021
Citation:
Webinar: Biological Control of Whiteflies in Squash, February 24, 2021 by Oscar Lilburd and Lorena Lopez, University of Florida. Registered 146, Attended 77, 278 views of recording
- Type:
Other
Status:
Published
Year Published:
2021
Citation:
Webinar: Incorporating Biological Control of Spider Mites into Tomato Pest Management Programs, March 1, 2021, by James Walgenbach and Tom Bilbo, North Carolina State University. Registered 145, Attended 84, 529 views of recording.
|
Progress 09/01/20 to 08/31/21
Outputs
Target Audience:Target audience of this project includes conventional and organic fruit and vegetable growers, county-, area- and state-wide extension agents and specialists, crop consultants, agricultural crop protection industry personnel, integrated pest management scientists and practitioners, and the general public. Changes/Problems:Due to COVID-19 restrictions on travel, access and personnel hiring imposed beginning in March 2020, virtually all laboratory-based and some field-based research projects were suspended or reduced in scope. Despite our best efforts, some experiments weredelayed or postponed. The research teams worked hard to make up for lost time since some of the restrictions were lifted. To ensure a successful completion of the project, a no-cost extension had been requested and was granted by NIFA, with a new project completion date of 31 August 2022. However, the teams are anticipating new COVID-19 restrictions being imposed due to the spread of the delta variant, and are planning for potential impacts to laboratory and field research. What opportunities for training and professional development has the project provided?Four post-doctoral research associates (Drs. Thomas Bilbo, Gunn Gill, Lorena Lopez and Deepak Shrestha) participated in this project and received training from their respective mentors at CU, UF and NCSU on developing and executing field research projects, data management, and presentations at scientific meetings, grower field days and extension meetings. They also have had opportunities to meet experts, fellow scientists, faculty and students, and expand their knowledge and skills in the field. All post-doctoral associates who participated in this project have successfully secured full-time employment in academic, governmental and industry settings. Efforts will be expanded to recruit new post-doctoral fellows, students and technicians to complete this project. Two graduate students (at UGA and CU) are participating in this project, and an agricultural economy graduate student (at CU) is working on assessing the economic benefits of this project part-time. They will be trained on proper experimental design, data collection and data management. Undergraduate students and technicians also received training on conducting field trials in the area of applied agricultural entomology. How have the results been disseminated to communities of interest?The research and extension teams utilize mainly direct interactions with and presentations to stakeholders at grower meetings and trade shows, as wellthe projectwebsite and webinars hosted by eOrganics, as a means of disseminating project results to communities of interest. The project website will also deliver project results in the form of publications, factsheets, webinars and videos.Peer-reviewed publications will also be developed at the later stage of this project to disseminate results to the scientific communities. What do you plan to do during the next reporting period to accomplish the goals?Due to the success of the webinar series developed by team members and delivered via eOrganics, the team will continue to seek out opportunity to organize and provide training opportunities to stakeholders, either online or in-person, at various online platforms or trade meetings (such as the Southeast Fruits and Vegetables Conference) in 2021-2022. However, new COVID restrictions will undoubtedly limit our ability to deliver training opportunities to stakeholders in an in-person setting. Therefore, additional efforts will be expended on organizing online training or in-print/digital extension publications to reach our stakeholders. Plans have been made for the next reporting period to complete several on-going experiments, which address all objectives outlined for this project. On-going experiments on developing optimal release timing and methods for predatory mites (Objectives 1.1 and1.2) will be completed in the next reporting period on organic squash and tomato fields in Georgia, Florida and North Carolina. The research team at NCSU will continue their experiments to identify factors important to the establishment, build-up and release of predatory mite populations as steps toward developing a grower friendly rearing systems of crop-adapted strains of predatory mites (Objective 1.3 and 1.4). The UGA team will continue its experiments on determining how predatory mite releases may impact whiteflies and thrips populations, as well as viral incidences associated with these important pests, in tomato production (Objective 1.6). The UF team will finish its experiment on interactions among natural enemies (Objective 2.3). The CU team will complete experiments designed to determine the compatibility of predatory mites and other natural enemies with organic insecticides (Objective 1.5 and 2.2) and to identify natural enemies found in surveys in the organics fields in FL, NC, GA and SC (Objective 2.1).A grower surveys and studies on the economic benefits of biological control in organic vegetable production will also be administered to stakeholders (Objective 1.7). An advisory board meeting will be planned for November 2021. Each research team will update the advisory board on the accomplishments and plan for future research and extension activities. The advisory board members (growers, industry partners and extension personnel) will provide the research teams with valuable suggestions on improving the practicality and reach of the research outcomes, and avenues for expanding the impacts of extension activities.
Impacts
What was accomplished under these goals?
NCSU research team (Walgenbach and Bilbo) has conducted experiments aimed at improving biocontrol of twospotted spider mites (TSSM) in tomatoes by the predatory mite Phytosieulus persimilis. An ongoing study conducted on commercial tomato farms compared two strains (tomato-adapted and bean-adapted) of P. persimilis for reducing TSSM populations and characterizing predator dispersal (Objective 1.3). In 2020, a small-plot trial failed to yield results despite more than five attempts at artificially infesting plants with TSSM, likely due to the difficulties in conducting TSSM trials under organic management in climates such as western NC. In another experiment, both strains were released the week TSSM were predicted to invade fields, based on historical sampling data. Preliminary results indicate the tomato-adapted strain more effectively suppressed TSSM and more readily dispersed. These results suggest both predator strains can result in excellent and long-lasting TSSM suppression. Results also reveal a limited dispersal of the predatory mites from release points. These results are contrary to most field releases made over the previous several years, and the factors causing poor dispersal are being investigated. Greenhouse experiments are underway to develop a grower-friendly rearing system for A. swirskii for release on commercial farms (Objective 1.4). The P. persimilis rearing system (described in a previous progress report) has been successful. Research team at Clemson University (Chong, Gill and Sikora) is conducting a study to evaluate the compatibility of seven native and mass-produced natural enemy species (such as P. persimilis, N. californicus and Orius insidiosus) with nine OMRI-listed insecticides (such as Bacillus thuringiensis and azadirachtin) and fungicides (such as Bacillus subtilis and cuprous oxide) (Objective 1.5 and 2.2). Preliminary data on P. persimilis and N. californicus suggest that residue of non-copper fungicides generally do not have significant negative impact on the survival and reproduction of the predators, however, some insecticides (such as pyrethrins) could significantly reduce predator survival. In a separate study, research team at NCSU investigated the effectiveness of different pesticide programs for managing key tomato pests and their impact on released P. persimilis. This research demonstrated that the soft foliar (some OMRI listed) and chemigation programs resulted in similar net profits to the hard foliar program but with the benefit of conserving biological control. The research team at the University of Georgia (UGA) (Srinivasan, Dutta and Coolong) conducted two field trials to evaluate the impact of predatory mite release methods on whiteflies and TYLCV incidence in a TYLCV-susceptible (Rosa Sicilian), a resistant cultivar (Skyway) and two TYLCV-resistant breeding lines of tomato, and a single CuLCrV-susceptible cultivar of squash (Objective 1.6). The trial was conducted in a certified-organic field at the Tifton Campus of UGA. Tomato and squash plants received no predatory mite (A. swirskii), or predatory mites were released at the base of the plant, on the foliage or via sachets. Whitefly adults and nymphs and disease symptom expression were monitored. The study on tomato failed because of severe bacterial leaf spot problem originated with seedling production in the greenhouse. After transplanting, weed management and transmission of some viruses from the weeds to the tomato further reduced plant survival in the field. The trial was terminated but will be repeated in the fall of 2021. On squash plants, predatory mite release method did not affect whitefly adults over 4 weeks. CuLCrV incidence was so high in the fall of 2020 that almost all plants, irrespective of treatments, were infected. As a result of high disease incidence, yield data were not taken. A survey of extension agents, specialists and crop consulting professionals have been developed by the economic team at Clemson University (Lamie and Levinson) to collect baseline data on IPM adoption level, IPM information delivery and the economic benefits of biological control in organic vegetable production (Objective 1.7). The survey seeks to establish the baseline by which growers can receive and benefit from extension or industrial education on organic pest management. A separate survey will be conducted for growers to gauge their adoption of IPM and biological control in their operation, benefits of the practices, and hurdles or limitations that prevent them from adopting IPM and biological control. Field surveys of thrips and whitefly natural enemies (Objective 2.1) have been completed in multiple organic fields in Florida, Georgia, North Carolina and South Carolina. For example, in 2020, sampling was conducted at nine organic farms and included seven squash fields and six tomato fields in North Carolina. Samples of natural enemies were collected through leaf collection, vacuuming, soil sampling and pitfall trapping, with weed pictures taken to associate natural enemies with surrounding vegetation. Samples are being processed and identified by the research team at Clemson University (Chong). Preliminary results suggested that a few natural enemies were present in the collected samples. UF research team (Liburd, Shrestha and Lopez) conducted two laboratory experiments addressing Objective 2.3 in September 2020 to April 2021, one with low (100 whiteflies + 100 chilli thrips) and one with high pest abundance (200 whiteflies + 200 chilli thrips). Fourteen treatments, consisted of a unique combination of no predator, native predator species (adult O. insidiosus or Geocoris punctipes) and predatory mite life stages (eggs, nymphs or adult female A. swirskii). Pests and predators were released onto squash leaf disks in plastic containers, after which the numbers of preys, predators and mites of all life stages were counted one and five days after release. Results suggested that < 40% of the adult predatory mites either moved away from the containers or were killed by the native predators, and > 60% eggs were consumed by predators when the pest densities were low. Survival rates of the life stages of predatory mites were higher when predators were not present or when pest densities were higher, suggesting potential negative impact of native predators or prey density on the predatory mites. Orius densities were low in all experiments perhaps due to their tendency for cannibalism, low pest densities or competition with other predators. Georcoris survival was consistently high in the experiments. The experiments did not find a clear pattern of interactions among the three predator species. To our knowledge, this is the first attempt to evaluated intraguild interactions between species from different arthropod classes (Insecta and Arachnida) and the methodology for experimentation is still in development. Other ecological factors need to be included when testing intraguild interactions; thus, experiments should be initiated in small artificial arenas to address these issues. Efforts to improve stakeholder knowledge of biological control in tomatoes and cucurbits are also underway (Objective 3). Through the eOraganic webinar series, the project team provided four webinars for stakeholders. The webinars covers topics on biological control options available, spider mite biocontrol in tomato, whitefly biocontrol in squash, and the relationship between biocontrol and virus transmission. 385 persons attended the webinars and the recordings of the webinars (posted on eOrganic website) were viewed 882 times up to mid-May 2021. Results and related topics (e.g., educational material and field identification techniques) have also been shared at field days (such as the NCSU annual Tomato Field Day), as well as at an extension agent training programs.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2021
Citation:
Bilbo, T.R., D. Owens, J. R. Golec, and J.F. Walgenbach. Impact of insecticide programs on pests, the predatory mite Phytoseiulus persimilis, and staked tomato profitability. J. Econ. Entomol. (submitted)
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Shrestha, D., M. Lopez, and O. Liburd. 2020. Evaluation of the predatory mite, Amblyseius swirskii (Acari: Phytoseiidae), for management of whiteflies in field-grown squash. Entomological Society of America Annual Meeting, November 17-20, 2020, Saint Louis, MO.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Bilbo, T. IPM Training for Diversified Fruit and Vegetable Producers. Planned for September 2021, held virtually and hosted by Yancey County (NC) Cooperative Extension.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Bilbo, T. R. and J. F. Walgenbach. 2021. Compatibility of pesticides with Phytoseiulus persimilis a specialist predator of twospotted spider mite. NC State Tomato Field Day 2021. August 2021, Mills River, NC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Bilbo, T. R., I. Meadows, and J. F. Walgenbach. 2021. Vegetable IPM Field Training for Cooperative Extension Agents. July 2021, Mills River, NC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Bilbo, T. R. and J. F. Walgenbach. 2021. Management options for thrips in tomatoes and peppers. Virtual 53rd Annual Meeting of NC Tomato Growers Association Winter Vegetable Conference. February 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Bilbo, T. R., S. Schoof, and J. F. Walgenbach. 2020. Insect Pest Management in Tomatoes. NC State Virtual Tomato Field Day 2020. August 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Chong, J., and G. Gill. 2021. Biological control options in vegetables. eOrganic webinar, 3 February 2021. Available: https://eorganic.org/node/34465
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Srinivasan, B., B. Dutta, and T. Coolong. 2021. Insect vectored viruses and their management in vegetables. eOrganic webinar, 10 February 2021. Available: https://eorganic.org/node/34471
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Liburd O. E. and L. Lopez. 2021. Biological control of whiteflies in squash. eOrganic webinar, 24 February 2021. Available: https://eorganic.org/node/34472
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Walgenbach, J., and T. Bilbo. 2021. Incorporating biological control of spider mites into tomato pest management programs. eOrganic webinar, 1 March 2021. Available: https://eorganic.org/node/34470
|
Progress 09/01/19 to 08/31/20
Outputs
Target Audience:The target audience of this project includes conventional and organic fruit and vegetable growers, county-, area- and state-wide extension agents and specialists, crop consultants, agricultural crop protection industry personnel, integrated pest management scientists,practitioners, and the general public. Changes/Problems:All research teams participating in this project were significantly affected by the COVID-19 pandemic in the spring and summer of 2020. Due to the pandemic-related modifications, the research team at Clemson University has delayed its hiring process for a post-doctoral researcher in completing its assigned portion of the project. eOrganic staff have been required to work from home; however, the staff has been granted permission to run webinars and, therefore, does not expect the administration of the website to be impacted directly. The UF team was not able to conduct the second season of Objective 1.2 in the field, which has to be delayed to spring 2021. The UF team also hasdelayed greenhouse trials associated with Objective 2.3 from spring to summer 2020. The UGA team has had to delay a trial on the efficacy of predatory mites and tomato resistance against thrips and tomato spotted wilt tospovirus incidence (Objective 1.6) from spring 2020 to fall 2020. Delays in research may result in delaysin results being posted on the project website as well as the delivery of webinars. Travel restrictions imposed by each collaborating institution and cancellations of grower meetings and trade shows also limit the ability of this project to directly deliver results and educational contents to growers and other stakeholders. The research and extension teams will develop webinars as a delivery method during the restrictive period, and may resume in-person interaction or education (as planned in the original proposal) at later dates when permitted. What opportunities for training and professional development has the project provided?Three post-doctoral research associates (Drs. Lorena Lopez, Deepak Shrestha and Thomas Bilbo) participate in this project and receive training from their respective mentors at UF and NCSU on developing and executing field research projects, data management, and presentations in the form of papers or posters at scientific meetings. They are given the opportunity to learn how to deliver results of this project effectively at grower field days and extension meetings. They also have had opportunities to meet experts, fellow scientists, faculty, and students and expand their knowledge and skills in the field. Theirinitial findings on this research have been presented atmeetings. Dr. Lorena Lopez has recently joined this project as a post-doctoral researcher, and will receive training under this project. Two graduate students (at UGA and Clemson University) have been recruited recently to participate full or part-time in this project. They will be trained on proper experimental design, data collection and data management. Undergraduate students and technicians also receive training on conducting field trials in the area of applied agricultural entomology. How have the results been disseminated to communities of interest?The research and extension teams utilize mainly direct interactions with and presentations to stakeholders at grower meetings and trade shows, as wellthe projectwebsite hosted by eOrganics, as a means of disseminating project results to communities of interest. Two examples of direct interactions includethe annual Tomato Field Day and an extension agent training program on fruiting vegetable IPM (held by NCSU) in 2019. The project website will also deliver project results in the form of publications, factsheets, webinars and videos.Peer-reviewed publications will also be developed at alater stage of this project to disseminate results to the scientific communities. What do you plan to do during the next reporting period to accomplish the goals?Plans have been made for the next reporting period to complete several on-going experiments, which address all objectives outlined for this project. On-going experiments on developing optimal release timing and methods for predatory mites (Objectives 1.1 and1.2) will be completed in the next reporting period in organic squash and tomato fields in Georgia, Florida and North Carolina. The research team at NCSU will continue their experiments to identify factors important to the establishment, build-up and release of predatory mite populations as steps toward developing a grower friendly rearing system of crop-adapted strains of predatory mites (Objective 1.3 and 1.4). The UGA team will continue its experiments on determining how predatory mite releases may impact the whiteflies and thrips populations, as well as viral incidences associated with these important pests, in tomato and squash production areas in Georgia (Objective 1.6). The UF team will finish its experiment on interactions among natural enemies (Objective 2.3). A post-doctoral research associate has been recruited by the Clemson University team to initiate and complete experiments designed to determine the compatibility of predatory mites and other natural enemies with organic insecticides (Objective 1.5 and 2.2) and to identify natural enemies found in surveys in the organic fields in FL, NC, GA and SC (Objective 2.1).A graduate student has been recruited by the Clemson University team to initiate grower surveys and studies on the economic benefits of biological control in organic vegetable production. A series of webinars and articles will be developed and deliver on the project website hosted by eOrganics in the coming months.
Impacts
What was accomplished under these goals?
In a study addressing Objective 1.2, the University of Florida (UF) research team (Liburd, Shrestha and Lopez) conducted the second season of an experiment in an organic field in Citra, FL, to evaluate the efficacy of release methods (sprinkle on leaves, on stem and sachet) of A. swirskii in controlling whitefly, viral disease, and silverleaf disorder in 'Zephyr', 'Eight ball' and 'Sunburst' squash cultivars. Sunn hemp and sweet alyssum planted in between the plots to reduce the between-plot movement of A. swirskii. Weekly leaf samplings were conducted from Week 4 to 8, and the total numbers of whiteflies (eggs and nymphs) andA. swirskii(eggs and motiles) on the leaves were determined. Adult whiteflies, plants showing silverleaf disorder symptoms and virus-infected plants were also counted on the same dates. Squash fruits were harvested and weighed. Results suggested that all release methods resulted in significantly higher numbers of A. swirskii than the unreleased control, with number increased over the season and fluctuated among the release methods. Higher numbers of whiteflies were present on 'Sunburst' than 'Zephyr' and 'Eight Ball'. All three A. swirskii release methods resulted in a lower number of whiteflies than control, and reduced the whitefly numbers over the season. A significantly higher number of virus-infected plants were observed on control than other release methods, with 'Eight Ball' having a lower number of infected plants than the other two cultivars. Release methods and squash cultivars interacted in influencing the number of infected plants. Control plots had a lower total yield than all other release methods. Only the cultivar had a significant effect on the number of plants showing silvering symptoms. Results suggested that releasing A. swirskii in the field one time and letting the population establish in the field can significantly increase the yield of the plants compared to not releasing A. swirskii. Sprinkling on top of leaves may be a better release method, and 'Eight ball' seems to be the cultivar with fewer whiteflies, silverleaf disorder and virus spread. The North Carolina State University (NCSU) research team (Walgenbach and Bilbo) has conducted a number of on-going field and greenhouse research experiments aimed at improving the biological control of spider mites in tomatoes by Phytosieulus persimilis. These include a replicated field trial testing the release timing and strain (tomato-adapted vs. bean-adapted) of P. persimilis at reducing naturally occurring spider mite populations (Objectives 1.1 and 1.3). P. persimilis from two different source colonies (bean and tomato) were released at two different time points into trial plots at a rate of 20,000 P. persimilis an acre. In addition, tomato-reared P. persimilis have been released at a similar rate into sections of several tomato fields operated by growers to determine efficacy at reducing spider mites under those settings. Data are currently being collected for all trials. The NCSU research team is also conducting several studies with the goal of developing grower friendly rearing systems that can be used to introduce and enhance biocontrol in organic tomato fields (Objective 1.4). In a field experiment, P. persimilis are being released onto spider mite-infested beans (a modified banker plant system) planted in a drive row between tomato treatment plots. P. persimilis populations increased in beans and dispersed into adjacent tomato plots. Greenhouse experiments are underway to determine optimal greenhouse conditions and timing of spider mite and P. persimilis infestations, which are useful information on developing a rearing system. The prototype system had produced more than 100,000 P. persimilis in a small group of approximately 360 tomato plants. This production required minimal greenhouse space and would service approximately five acres of commercial tomato field (rate: 20,000 P. persimilis/acre). In another field experiment, P. persimilis were released alone or in combination with supplement control OMRI-approved insecticides, such as Grandevo, and compared to Grandevo only and a non-treatment control (Objective 1.5). Data are being analyzed. Field surveys of thrips and whitefly natural enemies (Objective 2.1) have been conducted in multiple organic fields in Florida, Georgia, North Carolina and South Carolina. Samples of natural enemies had been collected through leaf collection, vacuuming, soil sampling and pitfall trapping, with weed pictures taken to associate natural enemies with surrounding vegetation. Samples will be processed and identified by the research team at Clemson University (Blubaugh and Chong) at later dates. Research team at UF had investigated potential for intraguild predation of A. swirskii eggs, nymphs and adults by Orius insidiosus and Geocoris punctipes (Objective 2.3). Greenhouse-grown zucchini plants were infested with a mix of sweetpotato whiteflies and chilli thrips, and leaf discs were collected and brought to the laboratory where A. swirskii, O. insidiosus and G. punctipes were released in different combinations. The numbers of prey and predators were counted 1, 3 and 5 days after predator releases. Data from this study are currently been analyzed. A graduate student has been recruited by the research team at Clemson University (Lamie) to initiate study on the economic benefits of biological control in organic vegetable production (Objective 1.7). Efforts to improve stakeholder knowledge of biological control in tomatoes and cucurbits are also underway (Objective 3). A project website has been developed by eOrganic (housed at Oregon State University) for posting results, publications and recorded webinars from the project, as they become available. Initial results and related topics (e.g., educational material and field identification techniques) have been shared at the annual Tomato Field Day (held by NCSU at the Mountain Horticultural Crops Research and Extension Center in Mills River, NC), as well as at an extension agent training program on fruiting vegetable IPM (held by NCSU at the Piedmont Research Station). A stakeholder advisory board meeting was held virtually in November 2019. Each research team updated the advisory board on the accomplishments and plan for future research and extension activities. The advisory board members (growers, industry partners and extension personnel) provided the research teams with valuable suggestions on improving the practicality and reach of the research outcomes, and avenues for expanding the impacts of extension activities.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Shrestha, D., M. Lopez, and O. Liburd. Evaluation of the predatory mite, Amblyseius swirskii (Acari: Phytoseiidae), for management of whiteflies in field-grown squash. Entomological Society of America Annual Meeting, November 17-20, 2020, Saint Louis, MO.
- Type:
Websites
Status:
Published
Year Published:
2019
Citation:
Biocontrol Tactics for Key Vegetable Insect Pests in the Southern U.S. Available at https://eorganic.info/biocontrol
|
Progress 09/01/18 to 08/31/19
Outputs
Target Audience:Target audience of this project includes conventional and organic fruit and vegetable growers, county and area-wide extension agents, state extension specialist, crop consultants, agricultural crop protection industry, integrated pest management scientists and practitioners, and the general public. Changes/Problems:With the originalProject Director moving to a new position, the PD role was changed from Rebecca Schmidt-Jeffris to Juang Horng Chong in 2019.This change in leadership delayed recruitment ofpersonnel associated with Clemson University's project objectives. A Post-doctoral associate will be employed by the PD to assist in conductingexperiment and extension outreach outlined in this project. On-farm sampling activities were initiated by the co-PIs nonethelessand are on-schedule by 2020. The UF research team did not encounter any major change and problems during this period. However, there were a few minor problems, including the team added a new experiment to determine the best release method of predatory mite in field squash. The team also plans to plant sunn hemp 2-3 weeks before planting of squash. The sunn hemp can grow taller than squash, thus providing a method of reducingA. swirskiimovement among treatment plots in the field. The team will also initiate the spring trial 3-5 weeks later in 2019 in order to achieve greater whitefly population density in the field. The team also plans to increaseA. swirskiirelease rate to about 50 per plants to result in a greater effect ofA. swirskiion whitefly population. The UGA research team encountered very low virus incidence and poor recovery of the predatory mites while sampling in 2018-2019. Virus pressure issues could be addressed by conducting the trial the following year or in multiple locations. Additional releases of predatory mites will be undertaken next year. What opportunities for training and professional development has the project provided?Dr. Deepak Shrestha and Dr. Thomas Bilbo are receiving their post-doctoral training at UF and NCSU, respectively. They have attended several conferences and meetings to discuss and share the results from project experiments. They also have opportunities to meet and network with experts, fellow scientists, faculty, and students, and expand their knowledge and skills in the field of sustainable agriculture and biological control with predatory mites. Three technicians received training in conducting this field trial at UGA. Two of them were recently hired, and this project provides a good training experience. A new graduate student has also joined the program at UGA this fall, and would benefit immensely from working on this project. He is currently doing his course work. Three undergraduate students are employed by this project at UF and UGA. They are learning about conducting sustainable agricultural research in the fields. Three undergraduates working as interns under this project at CU have been trained in insect sampling techniques on squash and tomato crops,and one has participated in related outreach programming focused identification of target pests and their natural enemies. Two are completing capstone projects related to this work: one is focused on preparing a display collection for outreach events, and another is analyzing arthropod pest and predator samples collected in on-farm from surveys of tomato and squash crops. How have the results been disseminated to communities of interest?Efforts to improve stakeholder knowledge of biological control in tomatoes and cucurbits, as outlined for Objective 3, are underway. Initial results and related topics (e.g., educational material and field identification techniques) have been shared at the annual Tomato Field Day (held by NCSU at the Mountain Horticultural Crops Research and Extension Center in Mills River, NC), as well as at an extension agent training program on fruiting vegetable IPM (held by NCSU at the Piedmont Research Station). Co-PI Blubaugh gave two workshops on pest/predator identification in 2019. One was attended by 39 vegetable farmers at the Aiken Soil and Water Conservation District, and another was attended by 13 farmers and focused on integrated/organic pest management in high tunnels (with a focus on cucurbit and tomato production). As part of Objective 3, a public project website has been published at https://eorganic.info/biocontrol. The website shows the project objectives and progress, and contains photos and some additional resources on diseases of tomatoes and cucurbits that are transmitted by insects as well as some trial results on yellow squash and zucchini disease resistance. What do you plan to do during the next reporting period to accomplish the goals?This project will proceed as planned and approved in the proposal. Several technical difficulties and shortcomings have been identified during the project, and methods in correcting these deficiencies have been devised (see Changes/Problems).
Impacts
What was accomplished under these goals?
The University of Florida (UF) research team (Liburd and Shrestha) has conducted two studies to improve release methods and timing of the predatory mite,Amblyseius swirskii,in open-field squash production system. In a study addressing Objective 1a, the team evaluated the effectiveness of different release methods of the predatory mite,A. swirskii,in controlling whiteflies, and their comparative effectiveness in various squash cultivars in an open-field experiment in the fall of 2018. Four different release methods were evaluated: a)approximately 1 ml of bran containing 30-35 A. swirskiisprinkled directly on the top of the leaves; b) approximately 1 ml of bran withA. swirskii placed on the base of the stem; c) Ulti-mite sachets placed on every other plant; and d) no-release control. There were 12 treatment combinations (3 cultivars x 4 release methods) replicated in four complete blocks. The total number of whitefly eggs and nymphs, andA. swirskiieggs and motiles, on the collected leaves were recorded. Yield data were taken, and fruits were harvested and weighed. The study showed that whiteflies preferred to feed on 'Zephyr' and 'Sunburst'. The least preferred cultivar, 'Eight Ball,' seems to be a better cultivar to reduce whitefly population and associated disease problems, such as sliverleaf disorder and virus spread. Placing A. swirskiion squash leaves resulted in larger mite population than sachet and stem release methods. Despite the presence of a higher number of whiteflies, sliverleaf disorder and virus-infected plants on 'Zephyr,' it produced higher yield and harbored a higher number of predatory mites than 'Sunburst' and 'Eight Ball.' In a study addressing Objective 1.1, the UF research team evaluated the effectiveness of different release timing (2, 4 and 6 weeks after planting) of A. swirskiion the effectiveness in controlling whitefly in the fields. The results were compared to no predatory mite release. Each treatment was replicated in 4 plots. Amblyseius swirskiiwas released by sprinkling 0.5 to 1 ml bran (approximately 25-35 mites) on top of the leaves of each plant. The total numbers of whitefly eggs and nymphs, andA. swirskiieggs and motiles were recorded. Yellow sticky traps and pan traps were collected to record other insects, such as aphid, thrips and natural enemies. The team found a significant interactive effect of release and sampling dates on total whiteflies and mites. The result from interaction on May 6thand May 13thshowed a higher number ofA. swirskiion 2-week release than other treatments. On May 20th, there were a higher number ofA. swirskiion 2- and 4-week treatment than 6-week treatment and control. On May 27th, there was a higher number ofA. swirskiion 2-week and 4-week, which was higher than 6-week. On the same date, 4-week treatment and control, and 6-week treatment and control had a similar number ofA. swirskii. On June 3rd, we found a higher number ofA. swirskiion treatments than control. On June 11th, we did not find differences among treatments. ReleasingA. swirskiican significantly and consistently reduce whitefly population and silverleaf disorder plant in the field than not releasingA. swirskii. A field study was conducted by the University of Georgia (UGA) research team (Srinivasan, Dutta and Coolong) to address Objective 1.6 and evaluated the impact of predatory mites on thrips abundance and TSWV incidence in both a TSWV-susceptible (Rosso Sicilian) and a resistant tomato cultivar (SV7631TD). The trial was conducted under certified-organic settings at the Tifton Campus of the University of Georgia. Thrips counts on the foliage and TSWV symptom expression were monitored on all plants. Four release locations evaluated on each cultivar: at the base of the plant, on the foliage, via sachets, and no releases. Disease spread was mapped and the percentage of infection in the presence and absence of thrips and predator was assessed. Other pests present at the time, such as whiteflies, aphids, and twospotted spider mites, were also recorded. The team found that thrips counts on the foliage did not vary among the treatments. Results suggested the addition of predators did not influence thrips densities. TSWV was only recorded in the susceptible cultivar (Rosso Sicillian). TSWV incidence increased with the release of predatory mites. Yields were not affected by predatory mite releases. Aphids populations were not influenced by mite releases, but there were more aphids on SV7631TD than Rosa Sicillian. Similarly, more whiteflies were also found on SV7631TD than Rosa Sicillian. No differences were observed between predatory mites and twospotted spider mite populations regardless of treatment or cultivars. North Carolina State University (NCSU) research team (Walgenbach and Bilbo) is conducting a number of field and greenhouse experiments to improve biological control of spider mites by Phytoseiulus persimilis. These experiments include a replicated field trial addressing Objective 1.1 and 1.3, and testing the release timing and strain (tomato-adapted vs bean-adapted) of P. persimilis at reducing naturally occurring spider mite populations. Phytoseiulus persimilis from two different source colonies (bean and tomato) were released at two different time points into trial plots at a rate of 20,000 P. persimilis per acre. In addition, tomato-reared P. persimilis have been released at a similar rate into sections of several tomato fields operated by growers to determine efficacy at reducing spider mites under those settings. In another field experiment addressing Objective 1.5, P. persimilis will be released alone or in combination with supplement control products, such as Grandevo. These treatments will be compared to Grandevo only and a non-treatment control. In another field experiment addressing Objective 1.4, P. persimilis are being released onto spider mite-infested beans (a modified banker plant system) planted in a drive row between tomato treatment plots. Beans were artificially infested with spider mites 3 weeks prior to natural infestations of spider mites in the adjacent tomatoes. P. persimilis populations increase in beans and disperse into adjacent tomato plots. Field data are currently being collected for all trials. Greenhouse experiments are underway to develop a grower-friendly rearing system to rear P. persimilis for release on small organic farms to address Objective 1.4. Optimal greenhouse conditions and timing of spider mite and P. persimilis infestations have been explored. Early results have produced upwards of 100,000 P. persimilis in a small group of tomato plants (approximately 360 plants). This production required minimal greenhouse and hoophouse space and would service approximately five acres of commercial tomato field. Research teams at NCSU, Clemson University (CU) and UGA have conducted diversity surveys (Objective 2.1) to determine the most common natural enemies of thrips, whiteflies and spider mites present in tomato and squash fields. Working with county and area-wide extension agents, a number of certified organic farms producing tomatoes and/or cucurbits have been contacted and sampling visits scheduled. Although pressure from these pests was relatively low in the 2018-2019 season, several known predators of these pest species were commonly found on our collaborating farms, including big-eyed bugs (Geocoris spp.)and minute pirate bugs (Orius spp.). Samples of endemic predatory mites are still being processed. After completing planned studies, research and extension teams will be able to provide a specific recommendation for the organic grower on how and when to releaseA. swirskiiand P. persimilis in the field to maximize the effect of predatory mites in controlling whitefly, thrips and spider mites, and to increase yield of tomatoes and cucurbits in the southern US.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Shrestha, D., M. Lopez, L. Lopez and O. Liburd. Testing of different release methods of Amblyseius swirskii in squash fields. Southeastern branch Entomological Society of America Annual Meeting, March 3-6, 2019, Mobile, AL.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Shrestha, D., M. Lopez and O. Liburd. Evaluation of different release methods and cultivars with the predatory mite, Amblyseius swirskii Athias-Henriot (Acari: Phytosidedae) to manage the whitefly [Bemisia tabaci (Gennadius) MEAM1] in organic squash. Florida Entomological Society Annual Meeting, July 21-24, 2019, Jupiter, FL.
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