Location: Fruit and Tree Nut Research
2017 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, and improved fundamental knowledge of natural enemies:
Sub-objective 1a: determine the efficacy of biocontrol agents in suppressing the pecan weevil.
Sub-objective1b: investigate the basic biology and ecology of biological control agents.
Sub-objective1c: investigate improved methods of nematode production.
Objective 2: Develop alternative control strategies for pecan aphids using banker plants, optimization of chlorosis-impeding plant bioregulators, and microbial control agents:
Sub-objective 2a: assessment of banker plants for control of pecan aphid spp. in orchards.
Sub-objective 2b: optimize orchard use of plant bioregulators to manage M. caryaefoliae injury.
Sub-objective 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, repellents, barriers, mating disruption, and application of entomopathogenic nematodes.
Sub-objective 3a: control stink bugs with reduced-risk insecticides.
Sub-objective 3b: assess repellants and barriers for management of peach pests.
Sub-objective 3c: mating disruption to manage sesiids borers.
Sub-objective 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 persistence through the use of cover crops and improved delivery. Additionally, pertinent basic studies on entomopathogen infection dynamics and delivery 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) identify and implement efficacious microbial control tactics. Suppression of key peach pests via reduced-risk insecticides, repellents, barriers, mating disruption, and application of entomopathogenic nematodes will be examined. Anticipated products from this research include novel alternative pest management tactics involving biocontrol agents, 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
Novel strategies for controlling a key pecan pest, pecan weevil, using a bacteria-based bio-insecticide, were explored. The bacteria-based bio-insecticide, which was found to provide similar levels of control compared with chemical insecticide standards, has now been found to also contribute to control of pecan aphids. Experiments to optimize the rate of application for this bacterial insecticide were conducted. Additionally, field experiments measured the efficacy of entomopathogenic nematodes in suppressing key peach pests such as peachtree borer. Specifically, curative applications of beneficial nematodes made in the spring to control peachtree borer were highly effective whereas chemical insecticides were not effective. These biocontrol approaches are promising for use against pecan weevil as well as key peach pests; grower adoption of the tactics has been initiated and has potential for expansion. Furthermore, fundamental research on beneficial nematodes was conducted and resulted in new discoveries including synergistic combinations between insect-killing bacteria and commercial fungicides, improvement of in vitro nematode production, and the ability of plant volatiles to induce increased infection in beneficial nematodes. The research on nematode and bacterial pesticides contributes to the goal of developing alternative biological solutions for control of key pecan and peach pests. Research on banker plants interplanted into pecan orchards has shown an increase in natural enemy populations leading to increased biological control of pecan aphid species. Interestingly, if the banker plants host a high number of alternative prey, the banker plants can become a sink for natural enemies that then do not visit pecan trees. Certain plant growth regulators have been shown, in both lab and orchard studies, to negatively affect growth and survival of the black pecan aphid. Demonstration orchards have further shown the utility of this tactic for management of the black pecan aphid. Additionally, growers have begun adopting this strategy and numerous acres of commercial orchards have been treated with plant growth regulators. Ongoing research seeks to identify even more potent plant growth regulators as regards negatively affecting the black pecan aphid.
Regarding stink bugs, especially the brown stink bug, this pest group is difficult to control. Research here has shown that the addition of a neonicotinoid insecticide to most insecticides improves control of stink bugs providing southeastern peach growers with better options for stink bug control well after bloom when honey bees are not in orchards. Research with physical barriers, e.g., fabric fencing, shows that adult stink bugs are unlikely to fly over and are thus prevented from attacking peach. Research also documents that trap crops along field edges can act as a sink decreasing stink bug movement into crops. Research toward mating disruption as a management tactic for the lesser peachtree borer has shown that an areawide approach will be necessary, but feasible. During the course of this project we have also shown that mating disruption against the lesser peachtree borer also disrupts the peachtree borer. This research has led to the development of a pheromone dispenser suitable for southeastern U.S. environmental conditions to provide season-long disruption with one early season application. At present, this pest management strategy is being adopted by a grower who is using it on 1,000 acres of peaches under an experimental use permit. When a full product label is granted by EPA in late 2017 for use in Georgia and South Carolina, it is expected that use by growers in both states will increase.
Accomplishments
1. Tiny worms can cure peaches of a harmful pest. The peachtree borer is a highly destructive insect pest that attacks stone fruit trees such as peaches, plums, nectarines, and cherries. Once the insect is established and bores into the roots of the tree there is no effective method to stop it. ARS researchers in Byron, Georgia, discovered that tiny worms (called beneficial or entomopathogenic nematodes) can kill peachtree borers even in springtime applications when the insects are well established in the roots. Chemical insecticides that were tested were not effective in springtime applications. This research provides a new environmentally-friendly control option for a serious pest of peaches and other crops.
2. Brown marmorated stink bug moves south. The brown marmorated stink bug that has been causing problems throughout the mid-Atlantic has now invaded the South. An ARS researcher in Byron, Georgia, has detected reproducing populations in central Georgia. Trapping in woodlands and pecan orchards has shown a vertical stratification of this pest with more capture in tree canopies than in ground traps. This knowledge is useful for developing sampling methods to detect the pest in pecan orchards with very tall trees.
3. Natural agents produce synergistic levels of fungicidal activity. Due to environmental concerns, and the increasing development of fungicide resistance, alternatives to standard chemical fungicides must be developed. ARS researchers in Byron, Georgia, discovered that certain bacteria produce natural fungicides. These bacteria are symbionts of beneficial nematodes that work together to kill insect pests. Now the nematode-bacteria team might be used for another purpose – controlling fungal diseases in plants. The bacterial by-products were found to work synergistically with existing commercial fungicides – so the mixtures work the best. The synergistic combinations have potential to enhance suppression of a variety of fungal plant diseases in orchards crops such as pecan and peach as well as other crops.
4. Lady beetles repelled by stink bug nymphs. Lady beetles are held in high regard for their ability to eat many plant pest species. But when it comes to eating stink bug pests, most species of lady beetles are not up to the job. ARS researchers in Byron, Georgia and Tifton, Georgia, found that small live stink bug nymphs were not fed on much by considerably larger lady beetles. But when dead stink bug nymphs were offered, the lady beetles ate them. Seems that the live stink bug nymphs live up to their name and are likely actively repelling these predators.
Review Publications
Shapiro Ilan, D.I., Morales Ramos, J.A., Rojas, M.G. 2016. In vivo production of entomopathogenic nematodes. In: Microbial-Based Biopesticides – Methods and Protocols. New York, NY: Humana Press. 1477:137-158.
Hazir, S., Shapiro Ilan, D.I., Bock, C.H., Hazir, C., Leite, L., Hotchkiss, M.W. 2016. Relative potency of culture supernatants of Xenorhabdus and Photorhabdus spp. on growth of some fungal phytopathogens. European Journal of Plant Pathology. 146(2):369-381.
Bai, G., Wang, X., Ma, H., Shen, G., Feng, X., Pan, J., Gu, X., Ruan, W., Shapiro Ilan, D.I. 2106. A comparison of novel entomopathogenic nematode application methods for control of the chive gnat, Bradysia odoriphaga (Diptera: sciaridae). Journal of Economic Entomology. 109(5):2006–2013.
Cottrell, T.E. 2017. Trap height affects capture of lady beetles (Coleoptera: Coccinellidae) in pecan orchards. Environmental Entomology. 46(2):343-352.
Shapiro Ilan, D.I., Arthurs, S., Lacey, L. 2017. Microbial control of arthropod pests of orchards in temperate climates. IN: Lacey, L. A. (Ed.), Microbial Agents for Control of Insect Pests: from discovery to commercial development and use. Academic Press, pp. 253-267.
Shapiro Ilan, D.I., Hazir, S., Glazer, I. 2017. Basic and applied research: Entomopathogenic nematodes. IN: Lacey, L. A. (Ed.), Microbial Agents for Control of Insect Pests: from discovery to commercial development and use. Academic Press, Amsterdam, pp. 91-105.
Leite, L., Shapiro Ilan, D.I., Hazir, S., Jackson, M.A. 2016. The effects of nutrient concentration, addition of thickeners, and agitation speed on liquid fermentation of Steinernema feltiae. Journal of Nematology. 48(2):126-133.
Shapiro Ilan, D.I., Cottrell, T.E., Mizell, R.F., Horton, D.L. 2016. Curative control of the peachtree borer using entomopathogenic nematodes. Journal of Nematology. 48(3):170-176.
Leite, L., Shapiro Ilan, D.I., Hazir, S., Jackson, M.A. 2017. A new medium for liquid fermentation of Steinernema feltiae: selection of lipid and protein sources. Nematropica. 46(2):147-153.
Tillman, P.G., Cottrell, T.E. 2016. Attraction of stink bug (Hemiptera: Pentatomidae) nymphs to Euschistus aggregation pheromone in the field. Florida Entomologist. 99:678-682.
Ni, X., Cottrell, T.E., Toews, M.D., Tillman, P.G., Buntin, G.D. 2016. Diurnal activities of the brown stink bug (Hemiptera: Pentatomidae) in and near tasseling corn fields. Journal of Entomological Science. 51(3):226-337.
Tillman, P.G., Cottrell, T.E. 2016. Stink bugs (Hemiptera: Pentatomidae) in pheromone-baited traps near crop field edges in Georgia, USA. Florida Entomologist. 99:363-370.
Tillman, P.G., Cottrell, T.E. 2017. Use of pheromones for monitoring phytophagous stink bug (Hemiptera: Pentatomidae) populations. In: Cokl, A., Borges, M., editors. Stinkbugs: Biorational Control Based on Communication Processes. Boca Raton, FL:CRC Press. p. 210-225.
Haelwaters, D., Zhao, S.Y., Cottrell, T.E., Kesel, A., Fiedler, L., Herz, A., Hesketh, H., Hui, C., Kleespies, R.G., Losey, J.E., Murray, K.M., Nedved, O., Pfliegler, W.P., Raak-Van Den Berg, C.L., Riddick, E.W., Shapiro Ilan, D.I., Smyth, R.R., Steenberg, T., Van Wielink, P.S., Viglasova, S., Zhao, Z., Ceryngier, P., Roy, H.E. 2016. Parasites of Harmonia axyridis: current research and perspectives. Biocontrol. 62:355-371.
