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

Location: Fruit and Tree Nut Research

2025 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 under the project, 6042-22000-024-00D. Novel strategies for controlling key pecan pests, such as pecan weevil, pecan aphids, fall webworm etc. using bio-insecticides were explored. Beneficial entomopathogenic (insect-killing) nematodes were tested against pecan pests including nut curculio, fall webworm, ambrosia beetles and flatheaded borers. Laboratory tests indicated high levels of virulence of beneficial nematodes to fall webworm and nut curculio, and thus substantial promise is held for field efficacy. Novel formulations for microbial bio-pesticides were investigated. A slow-release capsule formulation for beneficial nematodes was found to show extended persistence in field studies. New nanoparticle formulations provide exceptional UV protection to beneficial nematodes allowing the bio-pesticidal agents to survive longer in the environment and thereby kill more insect pests. Novel gel formulations that protect against UV radiation and desiccation were also tested when applying beneficial nematodes for control of peachtree. 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 tend to join groups of other nematodes. Additionally, the novel nematodes pheromones were found to enhance biocontrol efficacy in a rage of soil types. 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 natural enemies feeding on aphids attacking pecan resulting in decreased insecticide application. This research seeks to find efficient methods to direct those aphid-feeding insects from crape myrtle plants to pecan trees. Additionally, aphid research continues to identify important insect-plant interaction concerning elicitation of leaf chlorosis through black pecan aphid feeding injury and how to limit that injury using gibberellic acid. Implementation of physical barriers exploits stink bug movement patterns thus potentially reducing dispersal into orchards and learning the most efficacious products for their control is helping growers solve stink bug issues. 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. 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.

Accomplishments
1. Long-lasting worms help fight crop pests. Beneficial nematodes are tiny worms that kill insect pests such as pecan weevil, peachtree borer, small hive beetle, whiteflies and many others. These nematodes are commercially available natural biopesticides that do not harm humans, the environment or beneficial insects such as lady beetles. However, beneficial nematodes can be expensive to apply. Therefore, research to decrease costs and increase efficacy are warranted. If the nematodes can be applied at lower rates, and if their effects on pest control could last longer than just one season, then the use of these nematodes will be much more attractive and valuable to farmers. Commercially available nematode strains used to control pecan weevil (a key pest of pecan) were applied to pecan orchards at very low rates. USDA-ARS researchers from Byron, Georgia discovered that the nematodes reduced pecan weevil populations even in the second year-post application. The findings indicate that it may be possible to greatly reduce the number of beneficial nematodes that farmers need to apply, and that the nematodes may last longer than previously thought.

2. Reduced-risk insecticides to suppress stink bugs. Stink bugs can be serious pests of orchard crops including peach. The spatiotemporal abundance of stink bugs at the landscape level is greatly affected by presence of host plant species and the seasonal development of plant parts attacked by the stink bugs. Timing application of pesticide treatments is imperative to successful control but some broad spectrum treatments lead to secondary pests that then require control thus increasing crop damage and costs of control. Research conducted by scientists at the USDA-ARS research station in Byron, Georgia has identified that the active ingredient thiamethoxam, and especially when used with other less broad spectrum chemistries, can provide adequate control of most pest stink bugs. The recent establishment of the brown marmorated stink bug requires further testing because it is less sensitive to many chemistries effective against native stink bug pests.

Review Publications
Shapiro Ilan, D.I., Lewis, E.E. 2024. Entomopathogenic Nematodes as Biological Control Agents. CABI Publishing. Wallingford, UK. 554 pp. https://doi.org/10.1079/9781800620322.0000.
Shapiro Ilan, D.I., Lewis, E.E. 2024. Formulation and Application Technology for Entomopathogenic Nematodes. In: Entomopathogenic Nematodes as Biocontrol Agents. CABI Publishing. Wallingford, UK, pp. 201-218 https://doi.org/10.1079/9781800620322.0011.
Shapiro Ilan, D.I., Arthurs, S. 2024. Entomopathogenic Nematodes in Other Orchard Systems. In: Entomopathogenic Nematodes as Biocontrol Agents. CABI Publishing. Wallingford, UK, pp. 297-311. https://doi.org/10.1079/9781800620322.0017.
Han, R., Leite, L.G., Yan, X., Shapiro Ilan, D.I. 2024. Mass Production.In: Entomopathogenic Nematodes as Biocontrol Agents. CABI Publishing. Wallingford, UK, pp. 182-200. https://doi.org/10.1079/9781800620322.0010.
Lewis, E.E., Stevens, G., Shapiro Ilan, D.I. 2024. Behavioral Ecology of Entomopathogenic Nematodes. In: Entomopathogenic Nematodes as Biocontrol Agents. CABI Publishing. Wallingford, UK, pp. 112-125. https://doi.org/10.1079/9781800620322.0006.
Ha, B., Wei, X., Lu, P., Qing, H., Guo, J., Zhang, R., Chen, L., Li, X., Hu, B., Wang, S., Xu, Y., Fu, Z., Shapiro Ilan, D.I., Ruan, W. 2025. Natural UV protectants and humectants to improve the efficiency of Steinernema carpocapsae in controlling foliar pests. Pest Management Science. https://doi.org/10.1002/ps.8544.
Slusher, E.K., Shields, E., Harges, W., Shapiro Ilan, D.I. 2025. Evaluation of persistent versus commercial nematode strains for management of curculio caryae (horn) and other weevils in pecan. Biological Control. 202. https://doi.org/10.1016/j.biocontrol.2025.105705.
Perier, J.D., Wu, S., Arthurs, S.P., Toews, M.D., Shapiro Ilan, D.I. 2024. Persistence of the entomopathogenic nematode Steinernema feltiae in a novel capsule formulation. Biological Control. https://doi.org/10.1016/j.biocontrol.2024.105684.
Perier, J.D., Kaplan, F., Hobbs, S., Simmons, A.M., Lewis, E.E., Toews, M.D., Shapiro Ilan, D.I. 2025. Enhanced efficacy of pheromone treated entomopathogenic nematodes against whiteflies in foliar applications with a gel adjuvant. Journal of Invertebrate Pathology. 205. https://doi.org/10.1016/j.biocontrol.2025.105766.
Stock, P.P., Campos-Herrera, R., Shapiro Ilan, D.I. 2025. The First 100 Years in the History of Entomopathogenic Nematodes . Journal of Invertebrate Pathology. https://doi.org/10.1016/j.jip.2025.108302.
Mbata, G.N., Garland, K., Warsi, S., Li, Y., Ellis, J., Kanga, L.H., Shapiro Ilan, D.I. 2025. Comparative virulence of entomopathogenic nematodes to the small hive beetle (Aethina tumida Murray, Coleoptera: Nitilutidae). Journal of Nematology. https://doi.org/10.2478/jofnem-2025-0011.
Campos-Herrera, R., Georgis, R., Londono, D.K., Malan, A., Molina, C., Shapiro Ilan, D.I., Soler, R., Stock, S., Vandenbossche, B. 2025. Connecting academia and industry: advancing the use of entomopathogenic nematodes to tackle emerging challenges and opportunities in modern agriculture. Journal of Invertebrate Pathology. 211. https://doi.org/10.1016/j.jip.2025.108350.
Bock, C.H., Shapiro Ilan, D.I., Hotchkiss, M.W., Segura De Toledo, P.F., Wells, L., Schmidt, J.M., Pisani, C., Acebes-Doria, A.L. 2024. Scab intensity in pecan trees in relation to hedge-pruning methods. Plant Disease. 108(11):3381-3392. https://doi.org/10.1094/PDIS-10-23-2247-RE.
Yasin, M., Wakil, W., Kavallieratos, N.G., Eleftheriadou, N., Naeem, A., Qayyum, M., Asrar, F., Alhewairini, S., Shapiro Ilan, D.I. 2024. Dual-strategy Approach for Rhynchophorus ferrugineus Control: Endophytic Beauveria bassiana and Bacillus thuringiensis Topical Application. Crop Protection. https://doi.org/10.1016/j.cropro.2024.106954.
Machado, R.A., Muller, A., Hiltmann, A., Bhat, A., Puža, V., Malan, A.P., Castaneda-Alvarez, C., San-Blas, E., Duncan, L.W., Shapiro Ilan, D.I., Karimi, J., Lalramliana, Baimey, H. 2025. Genome-wide analyses provide insights into genetic variation, phylo- and co-phylogenetic relationships, and biogeography of the entomopathogenic nematode genus Heterorhabditis. Molecular Phylogenetics and Evolution. 204. https://doi.org/10.1016/j.ympev.2025.108284.
Gulzar, S., Slusher, E.K., Kaplan, F., Hobbs, S., Lewis, E.E., Shapiro Ilan, D.I. 2025. Effect of different soils on pheromone-enhanced movement of entomopathogenic nematodes. Journal of Nematology. 57(1). https://doi.org/10.2478/jofnem-2025-0009.
Siddique, A., Batchu, P., Shaik, A., Gurrapu, P., Tej Erukulla, T., Brown, D., Mahapatra, A., Panda, S., Morgan, E., Van Wyk, J., Shapiro Ilan, D.I., Kannan, G., Terrill, T. 2025. Evaluating the efficacy of bioelectrical impedance analysis using machine learning models for the classification of goats exposed to haemonchosis. Frontiers in Veterinary Science. 12. https://doi.org/10.3389/fvets.2025.1584828.
Slusher, E.K., Cottrell, T.E., Gariepy, T., Acebes-Doria, A.L., Coma, M.A., Toledo, P.F., Schmidt, J.M. 2024. A molecular approach to unravel trophic interactions between parasitoids and hyperparasitoids associated with pecan aphids. Journal of Insect Science. 24(4). https://doi.org/10.1093/jisesa/ieae071.
Tzu-Chin, L.J., Cottrell, T.E., Blaauw, B.R. 2024. Seasonal activity of plum curculio (Coleoptera: Curculionidae) in small Southeastern peach orchards. Environmental Entomology. 53(5):801-814. https://doi.org/10.1093/ee/nvae072.
Cottrell, T.E. 2024. Trap height affects capture of the pecan nut casebearer (Lepidoptera: Pyralidae). Journal of Entomological Science. 59(4)425-432. https://doi.org/10.18474/JES23-95.
Shapiro Ilan, D.I., Ment, D., Ramakrishnan, J., Rodriguez, M., Duncan, L. 2025. A century of advancement in entomopathogenic nematode formulation and application technology. Journal of Invertebrate Pathology. 212. https://doi.org/10.1016/j.jip.2025.108389.
Givindaraju, R., Hayter, J., Chong, J., Del Pozo-Valdivia, A.I., Cottrell, T.E., Walgenbach, J., Blaauw, B., Reding, M.E., Ranger, C.M., Joseph, S., Scheyer, T. 2025. Influence of trap types and ethanol release rates on captures of ambrosia beetles in apple, peach, pecan and ornamentals. Journal of Applied Entomology. 149:74-87. https://doi.org/10.1111/jen.13361.