Research Project: Novel Approaches for Managing Key Pests of Peach and Pecan

Location: Fruit and Tree Nut Research

2024 Annual Report

Objectives
Objective 1: Develop alternative control strategies for the pecan weevil based on enhanced production, formulation delivery, and efficacy of microbial control agents, as well as improved fundamental knowledge of entomopathogens: Subobjective 1a. Determine the efficacy of biocontrol agents in suppressing the pecan weevil. Subobjective 1b. Investigate the basic biology and ecology of biological control agents. Subobjective 1c. Investigate improved methods of nematode pheromone production. Objective 2: Develop control strategies for pecan aphids using banker plants, optimization of chlorosis-impeding plant bioregulators, and the use of microbial control agents: Subobjective 2a. Assessment of banker plants for control of pecan aphid spp. in orchards. Subobjective 2b. Optimize use of plant bioregulators to manage M. caryaefoliae injury. Subobjective 2c. Implement microbial control agents for pecan aphid management. Objective 3: Develop alternative control strategies for key peach pests (plum curculio, sesiid borers, and stink bugs) via reduced-risk insecticides, barriers, mating disruption and application of entomopathogenic nematodes: Subobjective 3a. Determine efficacy of reduced-risk insecticides against stink bugs. Subobjective 3b. Determine efficacy of physical and insecticidal barriers against peach pests. Subobjective 3c. Use mating disruption to manage sesiid borers. Subobjective 3d. Develop entomopathogenic nematodes for control of key peach pests.

Approach
Pecan and peach are important horticultural crops that can suffer severe losses in yield due to insect damage. The overall goal of this project is to provide economically and environmentally sound pest management strategies for control of key insect pests of pecan and peach. Objectives include alternative control strategies for key pecan pests (pecan weevil and pecan aphids) and key peach pests (plum curculio, sesiid borers, and stink bugs). Suppression of pecan weevil will focus on developing microbial control tactics including integrated entomopathogen applications and enhanced entomopathogen efficacy through improved delivery and formulation. Additionally, pertinent basic studies on entomopathogen foraging dynamics and production technology will be addressed. Management strategies for pecan aphids will 1) optimize usage of chlorosis-impeding plant bioregulators against the black pecan aphid, 2) incorporate banker plants into orchards for pecan aphid management and 3) implement efficacious microbial control tactics. Suppression of key peach pests via reduced-risk insecticides, physical and insecticidal barriers, mating disruption, and application of entomopathogenic nematodes will be examined. Anticipated products from this research include novel alternative pest management tactics involving microbial biocontrol agents, mating disruption, plant bioregulators, or other innovative strategies, improved methods for production, formulation, and delivery of biocontrol agents, and the filling of key knowledge gaps in basic insect pest and natural enemy biology and ecology.

Progress Report
This report serves to document progress of research conducted by ARS researchers at Byron, Georgia under the project, 6042-22000-024-00D. Novel strategies for controlling key pecan pests, such as pecan weevil, pecan aphids, etc. using bio-insecticides were explored. Beneficial entomopathogenic (insect-killing) nematodes were tested against pecan pests including pecan weevil, ambrosia beetles and flatheaded borers. Laboratory tests indicated high levels of virulence of beneficial nematodes to ambrosia beetles (for the first time); however, field tests thus far have not supported the laboratory virulence findings. Methods to enhance ambrosia beetle control in the field using entomopathogenic nematodes are being explored. Low application rates of novel persistent beneficial nematode strains were field tested for efficacy against pecan weevil in comparison to reduced rates of commercial nematode strains. Interestingly, in the second year of the experiment, a single application of nematodes the previous year continued to produce high levels of pecan weevil control in the subsequent year. This finding opens a new potential avenue for low-cost weevil control, i.e., persistent control using beneficial nematodes for multiple seasons at low rates. Additionally, root-feeding weevils (such as fuller rose beetle) were controlled with very low rates of commercial entomopathogenic strains. In demonstration trials, entomopathogenic nematodes were also tested against peachtree borer. High levels of control were observed (>90%). The use of entomopathogenic nematodes for control of peachtree borer is now included in the Georgia Peach Pest Management spray guide. Additionally, new potential formulations to protect the beneficial nematodes from environmental extremes were explored. Fundamental research on entomopathogenic nematode behavior was conducted. Previous research indicated that beneficial nematodes move through soil in packs, like a pack of wolves seeking their prey. New research indicated that nematodes that tend to “lead” the pack are also more infective to insects. The research on nematode and fungal bio-pesticides contributes to the goal of developing alternative biological solutions for control of key pecan and peach pests and has led to adoption by growers and industry. Crape myrtle banker plants interplanted in pecan orchards can be used to increase populations of aphid-feeding insects in the orchards. This research is leading to finding the most efficient means to direct those aphid-feeding insects from crape myrtle plants to pecan.Field trials have shown that physical barriers alter stink bug movement and may have potential reducing dispersal into orchards. Mating disruption for management of the lesser peachtree borer and the peachtree borer attacking peach does disrupt non-target species of Sesiidae but this effect is mostly limited to peach orchards and the nearby surrounding habitat. Collaborative research continues to identify native egg parasites of the invasive brown marmorated stink bug and native stink bugs in pecan orchards with and without orchard floor cover crops.

Accomplishments
1. Specialized pheromones enhance the bio-pesticidal efficacy of beneficial nematode worms for control of the pecan weevil. Pecan weevil is a major pest of pecans. Chemical insecticides are used to control pecan weevil, but these pesticides can be harmful to humans and the environment. Therefore, safe alternative approaches are needed. Beneficial nematodes (small round worms) are safe biocontrol agents that are commercially available. However, nematode efficacy in controlling pecan weevil can be variable and expensive. Specialized pheromones were found to “flip a switch” in the nematodes and make them disperse more and infect insects better. In the first ever field tests using these pheromones, ARS scientists at Byron, Georgia documented increased control of pecan weevil when using nematodes with the pheromones compared to nematode application without pheromones. This discovery may lead to greatly improved biological control of pecan weevil, and the nematode-pheromone approach could be applicable to control of many other pests in various cropping systems.

2. Banker plants for pecan aphid management. Three species of foliar-feeding aphids attack pecan. ARS researchers at Byron, Georgia suggest a possible alternative management approach for aphids is an interplanting of crape myrtle in pecan orchards. The crape myrtle aphid (that does not attack pecan) serves as a food source for aphid-attacking insects thus increasing populations of beneficial insects in orchards. Dispersal of the beneficial insects from crape myrtle to pecan aids in aphid management.

Review Publications
Stevens, G., Muhammad, U., Gulzar, S., Stevens, A., Pimentel, E., Erdogan, H., Schliekelman, P., Kaplan, F., Alborn, H.T., Shapiro Ilan, D.I., Lewis, E.E. 2024. Group movement in entomopathogenic nematodes: aggregation levels vary based on context. Journal of Nematology. 203.Article 108070. https://doi.org/10.1016/j.jip.2024.108070.
Slusher, E.K., Lewis, E., Stevens, G., Shapiro Ilan, D.I. 2024. Movers and shakers: do nematodes that move more infect more. Biological Control. 203. Article 108060. https://doi.org/10.1016/j.jip.2024.108060.
Leite, L.G., Chacon-Orozco, J.G., Shapiro Ilan, D.I., Baldo, F.B., Cardoso, J.M. 2023. Effects of temperature for optimizing production and storage of Steinernema rarum in a novel biphasic process, and efficacy of the nematode against Sphenophorus levis. Biological Control. 187. Article 105381. https://doi.org/10.1016/j.biocontrol.2023.105381.
Perier, J.D., Kaplan, F., Lewis, E.E., Alborn, H., Schliekelman, P., Toews, M.D., Shapiro Ilan, D.I. 2024. Enhancing entomopathogenic nematode efficacy with pheromones: a field study targeting the pecan weevil. Journal of Invertebrate Pathology. 56(1). Article e2024. https://doi.org/10.2478/jofnem-2024-0002.
Li, X., Shapiro Ilan, D.I., Tarasco, E., Qizhi, L., Yang, W., Yi, J., Cheng, C., Zhang, H., Fu, H. 2024. Thiourea as a polyphenoloxidase inhibitor enhances host infection by the entomopathogenic nematode, heterorhabditis beicherriana. Biological Control. 191. Article 105474. https://doi.org/10.1016/j.biocontrol.2024.105474.
Alwaneen, W., Wakil, W., Tahir, M., Qayyum, A., Rasool, K., Husain, M., Aldawood, A., Shapiro Ilan, D.I. 2024. Horizontal transmission of entomopathogenic fungi in red palm weevil, rhynchophorus ferrugineus (olivier) in date palm. Agronomy Journal. 14(4): 642. https://doi.org/10.3390/agronomy14040642.
Zhang, M., Spaulding, N.R., Reddy, G.V., Shapiro Ilan, D.I. 2024. The efficacy of entomopathogenic nematodes plus an adjuvant against Helicoverpa zea and Chrysodeixis includens in aboveground applications. Journal of Nematology. 56(1):14. https://doi.org/10.2478/jofnem-2024-0018.
Toledo, P., Phillips, K., Schmidt, J., Bock, C.H., Wong, C.R., Hudson, W., Shapiro Ilan, D.I., Wells, L., Acebes-Doria, A.L. 2023. Canopy hedge pruning in pecan production differentially affects groups of arthropod pests and associated natural enemies. Crop Protection. 176. Article 106521. https://doi.org/10.1016/j.cropro.2023.106521.
Li, J., Wei, X., Pei, Z., Sun, J., Xi, J., Li, X., Shapiro Ilan, D.I., Ruan, W. 2024. Volatile organic compounds released from entomopathogenic nematode-infected insect cadavers for the biocontrol of meloidogyne incognita. Pest Management Science. 155. Article 104527. https://doi.org/10.1016/j.biocontrol.2020.104527.
Li, Y., Mbata, G.N., Simmons, A.M., Shapiro Ilan, D.I., George, S. 2024. Management of Bemisia tabaci on vegetables using entomopathogens. Crop Protection. 180. Article 106638. https://doi.org/10.1016/j.cropro.2024.106638.
Hofman, C.O., Steffan, S.A., Shapiro Ilan, D.I. 2023. A sustainable grower-based method for entomopathogenic nematodes production. Journal of Insect Science. 23(5). https://doi.org/10.1093/jisesa/iead025.
Wakil, W., Gulzar, S., Prager, S., Shapiro Ilan, D.I. 2023. Efficacy of entomopathogenic fungi, nematodes and spinetoram combinations for integrated management of Thrips tabaci: a two-year onion field study. Pest Management Science. 79(9):3227-3238. https://doi.org/10.1002/ps.7503.
Wu, S., Towes, M.D., Behle, R.W., Barman, A.K., Sparks, A.N., Simmons, A.M., Shapiro Ilan, D.I. 2023. Post-application field persistence and efficacy of cordyceps javanica against bemisia tabaci. The Journal of Fungi. 9(8):827. https://doi.org/10.3390/jof9080827.
Wu, S., Li, Y., Towes, M.D., Mbata, G., Shapiro Ilan, D.I. 2023. Novel formulations improve the environmental tolerance of the entomopathogenic nematodes. Biological Control. 186. Article 105239. https://doi.org/10.1016/j.biocontrol.2023.105239.
Broadhead, G.T., Cottrell, T.E., Beck, J.J. 2024. Leaffooted bugs: insect pest species of growing concern for agriculture. Journal of Agriculture and Food Chemistry. 72(5):2467-2472. https://doi.org/10.1021/acs.jafc.3c06763.
Kean, J.M., Manoukis, N., Dominiak, B.C. 2023. Review of surveillance systems for tephritid fruit fly threats in Australia, New Zealand, and the United States. Journal of Economic Entomology. 117(1):8-23. https://doi.org/10.1093/jee/toad228.
Pisani, C., Cottrell, T.E. 2024. Impact of Pecan Leafroll Mite (Acari: Eriophyidae) on Pecan Foliage. Journal of Entomological Science. 59(1):86-89. https://doi.org/10.18474/0749-8004-59.1.86.
Broadhead, G.T., Cottrell, T.E., Beck, J.J. 2024. Leaffooted bugs: insect pest species of growing concern for agriculture. Journal of Agricultural and Food Chemistry. https://doi.org/10.1021/acs.jafc.3c06763.
Tillman, P.G., Grabarczyk, E.E., Kesheimer, K.A., Cottrell, T.E. 2024. Trapping strategy and diel periodicity affect capture rate of Halyomorpha halys (Hemiptera: Pentatomidae) in agroecosystems. Environmental Entomology. 53(2):237-248. https://doi.org/10.1093/ee/nvae010.