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

Location: Fruit and Tree Nut Research

2023 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, 6042-22000-024-000D. 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) and field tests are underway to determine efficacy. Laboratory and field tests indicate promise for control of flatheaded borers in pecan and walnut systems. 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; no substantial differences noted thus far (the test is being repeated). However, root-feeding weevils (such as fuller rose beetle) were controlled with very low rates of commercial entomopathogenic strains. In a second year of field trials, addition of specialized pheromones to beneficial nematode mixtures caused increased control of pecan weevil. This was the first field test of using nematode pheromones to enhance biocontrol efficacy in the field. Entomopathogenic nematodes were also tested against peachtree borer. High levels of control were observed (>90%), which were equal to chemical insecticide standards. Moreover, other insect pests in peach systems such as root-feeding weevils were also suppressed as a secondary benefit. The use of entomopathogenic nematodes for control of peachtree borer is now included in the Georgia Peach Pest Management spray guide. Novel bacterial metabolites derived from entomopathogenic (insect-killing) nematodes were found to kill soft-bodied insects such as pecan aphids and whiteflies but were deemed relatively safe to beneficial insects such as lady beetles. 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 illustrated joining-behavior, i.e., how nematodes join other groups of nematodes to increase their chances of finding insect hosts. 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. Recent research has shown that treatment of pecan nuts infested with pecan weevil larvae using electronic cold pasteurization can provide a means to kill larvae within nut. This process could alleviate any quarantine concerns regarding movement of pecan nuts potentially infested with pecan weevil larvae. Greenhouse and laboratory studies show that black pecan aphid-damaged areas of pecan leaves may not take up gibberellic acid as readily as non-damaged areas. This highlights the need to treat pecan foliage with gibberellic acid before black pecan aphid populations increase and cause damage. Mating disruption for management of the lesser peachtree borer and the peachtree borer attacking peach can be implemented in small acreage orchards provided that the orchards are away from peach orchards not under mating disruption. Collaborative research continues to identify native egg parasites of the invasive brown marmorated stink bug in orchard and woodland habitats. Understanding the importance of these native parasites may negate the need to pursue release of non-native egg parasites.

Accomplishments
1. Beneficial nematode worms control peachtree borer and provide secondary benefits. The peachtree borer is a major pest of peaches and other stone fruits. Control of the pest is difficult due to the loss of the chemical insecticide chlorpyrifos. Moreover, due to environmental concerns, it is desirable to reduce the amount of chemical pesticides applied into the ecosystem. ARS scientists in Byron, Georgia, discovered that beneficial nematodes (small round worms) control peachtree borer as well or better than any chemical insecticide. The nematodes also provide secondary benefits by killing other pests in the orchards such as root-feeding weevils. The use of beneficial nematodes for control of peachtree borer is now recommended by university extension. The technology offers growers an effective and environmentally safe method of pest control.

2. A new system for farmers to grow their own environmentally-friendly bio-insecticides. Beneficial nematodes (small round worms) are environmentally friendly bio-insecticides. These nematodes are produced commercially and used to control a wide variety of economically important pests. However, the nematodes can be expensive. ARS scientists in Byron, Georgia, and Madison, Wisconsin, developed a novel system that enables farmers to grow their own beneficial nematodes. The process is sustainable and does not require any outside input or scientific equipment. The team published details on the system in a special collection of scientific articles on mass production of beneficial organisms. Some farmers have already started to adapt a modified version of the system.

3. Electronic cold pasteurization for in-shell weevil control. Pecan weevil is typically an in-season pest that is managed by controlling adult pecan weevils in orchards. Nonetheless, control of weevils in the orchard is sometimes less than perfect leading to pecan nuts being infested with pecan larvae. When larvae persist in the nut after harvest, distribution of pecan nuts to shelling facilities and to various marketing venues opens the possibility of distributing pecan weevil to new areas. Recent research by ARS scientists in Byron, Georgia, has shown that treatment of pecan nuts infested with pecan weevil larvae using electronic cold pasteurization can provide a means to kill larvae within nut. This process could alleviate any quarantine concerns regarding movement of pecan nuts potentially infested with pecan weevil larvae.

Review Publications
Mbata, George, Li, Y., Shapiro Ilan, D.I. 2022. Formulation of an IPM package for the management of pangaeus bilineatus (say) (heteroptera: cynidae)from combinations of entomopathogens and insecticides. Journal of Pest Science. 78 : 4719-4727. https://doi.org/10.1002/ps.7092.
Wong, C.R., Shapiro Ilan, D.I., Hofman, C.O., Blaauw, B., Chavez, D., Jagdale, G., Mizell, R. 2022. Using the nematode, Steinernema Carpocapsae to control peachtree borer (Synanthedon Exitiosa): Optimization of application rates and secondary benefits in control of root-feeding weevils. Agronomy Journal. 12:2689. https://doi.org/10.3390/agronomy12112689.
Kotiarevski, L., Cohen, R., Ramakrishnan, J., Wu, S., Ananth, K., Feldbaum, R., Yaakov, N., Zelinger, E., Belausov, E., Shapiro Ilan, D.I., Glazer, I., Ment, D., Mechrez, G. 2022. Individual coating of entomopathogenic nematodes with titania (TiO2) nanoparticles based on oil-in-water Pickering emulsion: A new formulation for biopesticides. Journal of Agricultural and Food Chemistry. 70 : 13518-13527. https://doi.org/10.1021/acs.jafc.2c04424.
Wu, S., Mechrez, G., Ment, D., Toews, M.T., Ananth, K., Feldbaum, R., Shapiro Ilan, D.I. 2022. Tolerance of Steinernema carpocapsae infective juveniles in novel nanoparticle formulations to ultraviolet radiation. Journal of Invertebrate Pathology. 196,107851. https://doi.org/10.1016/j.jip.2022.107851.
Stevens, G., Erdogan, H., Pimentel, E., Dotson, J., Stevens, A., Shapiro Ilan, D.I., Kaplan, F., Schliekelman, P., Lewis, E. 2023. Group joining behaviors in the entomopathogenic nematode Steinernema glaseri. International Journal of Parasitology. 181 : 105220. https://doi.org/10.1016/j.biocontrol.2023.105220.
Wu, S., Toews, M., Cottrell, T.E., Schmidt, J., Shapiro Ilan, D.I. 2022. Toxicity of photorhabdus luminescens and xenorhabdus bovienii bacterial metabolites to pecan alhids (hemiptera: aphididae) and the lady beetle harmonia axyridis (coleoptera: coccinellidae). Journal of Invertebrate Pathology. 194 : 107806. https://doi.org/10.1016/j.jip.2022.107806.
Wakil, W., Tahir, M., Ghazanfar, M., Qayyum, M., Yasin, M., Maqsood, S., Asrar, M., Shapiro Ilan, D.I. 2022. Microbes, dodonaea viscosa and chlorantraniliprole as components of helicoverpa armigera IPM program: A three region open-field study. Agronomy Journal. 12 : 1928. https://doi.org/agronomy12081928.
Williams III, L.H., Cherry, R., Shapiro Ilan, D.I. 2022. Effect of host size on susceptibility of melanotus communis (coleoptera: elateridae) wireworms to entomopathogens. Journal of Nematology. 54(1):3922. https://doi.org/10.2478/jofnem-2022-0033.
Geisert, R.W., Huynh, M.P., Pereira, A.E., Shapiro Ilan, D.I., Hibbard, B.E. 2023. An improved bioassay for the testing of entomopathogenic nematode virulence to the western corn rootworm (Diabrotica virgifera virgifera) (Coleoptera: Chrysomelidae): with focus on neonate insect assessments. Journal of Economic Entomology. 116(3): 726-732. https://doi.org/10.1093/jee/toad052.
Tian, C., Zhu, F., Li, X., Zhang, J., Puza, V., Shapiro Ilan, D.I., Zhao, D., Liu, J., Zhou, J., Ding, Y., Wang, J., Ma, J., Zhu, X., Li, M. 2022. Steinernema populi n. sp. (panagrolaimomorpha, steinernematidae), a new entomopathogenic nematode species from China. Journal of Helminthology. 96 : e57. https://doi.org/10.1017/S0022149X22000426.
Grabarczyk, E.E., Cottrell, T.E., Schmidt, J.M., Tillman, P.G. 2023. Low incidence of avian predation on the brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae) in southeastern orchard systems. Insects. 14:595. https://doi.org/10.3390/insects14070595.
Tillman, P.G., Grabarczyk, E.E., Balusu, R., Kesheimer, K., Blaauw, B., Sial, A., Vinson, E., Cottrell, T.E. 2023. Predation and parasitism of naturally occurring and sentinel stink bug egg masses of halyomorpha halys (Stal) and nezara viridula (L.) (hemiptera: pentatomidae) in various southeastern habitats. Journal of Insect Science. 23(2):1-12. https://doi.org/10.1093/jisesa/iead012.
Cottrell, T.E., Tillman, P.G., Grabarczyk, E.E., Toews, M., Sial, A., Sriyanka, L. 2023. Habitat and vertical stratification affect capture of stink bugs (Hemiptera: Pentatomidae) and biological control of the invasive brown marmorated stink bug. Environmental Entomology. 20:1-3. https://doi.org/10.1093/ee/nvad061.
Gaffke, A.M., Shapiro-Ilan, D., Alborn, H.T. 2022. Deadly scents: Exposure to plant volatiles increases mortality of entomopathogenic nematodes during infection. Frontiers in Physiology. 13:978359. https://doi.org/10.3389/fphys.2022.978359.