Location: Fruit and Tree Nut Research
2016 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
This report serves to document progress of research conducted under in the project, 6042-22000-023-00D. Novel strategies for controlling a key pecan pest, pecan weevil, using beneficial nematodes, fungi and a bacteria-based bio-insecticide were explored and new control methods were developed. The bacteria-based bio-insecticide provided similar levels of control compared with chemical insecticide standards. Additionally, field experiments measured the efficacy of entomopathogenic nematodes in suppressing key peach pests (plum curculio and peachtree borer and lesser peachtree borer). Specifically, research on novel beneficial nematode formulation for lesser peachtree borer control was advanced; experiments on peachtree borer focused on developing curative applications in the spring, and experiments on plum curculio measured the potential of using trap trees and thereby substantially reducing the treatment area required and associated costs. 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 antibiotic properties, improvement of in vitro nematode production, and the contribution of bacterial cheaters in causing nematode attenuation. 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. 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. 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 SE 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 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.
Accomplishments
1. Fire-gel protects beneficial nematodes in a single spray. Beneficial nematodes can control a wide variety of soil-dwelling insect pests. However, the nematodes are sensitive to UV radiation and desiccation and therefore have difficulty controlling insects that attack plants aboveground. ARS researchers from Byron, Georgia, used a fire-gel to protect the nematodes from harmful environmental conditions. The gel is usually used to protect houses or other structures from fire. In this new research, the ARS researchers discovered that the nematodes can be used as a single spray in combination with the gel to kill harmful insect pests. The researchers used the gel and nematode combination to control the lesser peachtree borer, a major pest of peaches, plums and other stone fruit trees. The lesser peachtree borer attacks the tree’s trunk and scaffold limbs causing severe reductions in productivity. The nematode-gel combination enhances natural pest control and may be applicable in various other cropping systems.
2. Cheaters reduce virulence in beneficial nematodes. Beneficial nematodes are environmentally friendly bio-insecticides that are used to control a wide variety of economically important insect pests. However, when the nematodes are cultured repeatedly, they can lose their virulence (killing-power); this is called attenuation. ARS researchers from Byron, Georgia, discovered one of the causes for attenuation. Some nematodes let the others do the work of the killing the insect while the lazy nematodes (called cheaters) sit back and take a rest. If a lot of cheaters develop, then the whole nematode population will be less able to kill insect pests. Fortunately, the researchers also discovered that the number of cheaters can be reduced by controlling the number of nematodes that invade the insect. Overcrowding inside the dead insect, where the nematodes reproduce, causes more cheaters to develop. This research contributes significantly to fundamental understanding of host-pathogen relationships, and provides methodology to improve the quality of nematodes as effective biological control agents.
3. Ladybird, ladybird fly away home. Another reason for the successful establishment of the invasive multicolored Asian lady beetle may include the beetle’s exploitation of pests wherever they occur on a plant. An ARS researcher from Byron, Georgia, discovered that in tall pecan orchards, this invasive predator is found feeding on pecan aphids at all heights in the pecan canopy and also on aphids on plants in the orchard understory. Most other lady beetle species either occur low (on plants in the pecan orchard understory) or high (in the pecan tree canopy) but not at all vertical strata of the orchard as does the invasive multicolored Asian lady beetle. Utilizing prey at all vertical strata is not a strategy employed by many other lady beetle species and may give this invasive predator an advantage.
4. Barriers keep stink bugs away from peaches. Stink bugs are notorious, season-long pests of peach that are difficult to control. ARS researchers at Byron and Tifton, Georgia, erected fabric fencing around peach trees to stop stink bugs. The fencing prevented stink bugs from reaching peach trees and damaging fruit. Apparently, the stink bugs were not inclined to fly up and over the barrier. This research proves that barriers, and likely dense plant barriers, can affect stink bug movement and even direct movement around and away from host plants.
More than 33% of commercial pecan acreage is managed on small farms (< $250,000). Pest management research activities, such as biological control studies, that are conducted by ARS scientists at the Southeastern Fruit and Tree Nut Research lab, Byron, Georgia, may be of substantial benefit to growers on small farms with limited resources.
Review Publications
Hazir, S., Shapiro-Ilan, D.I., Hazir, C., Leite, L., Cakmak, I., Olson, D.M. 2016. Multifaceted effects of host plants on entomopathogenic nematodes. Journal of Invertebrate Pathology. 135:53-59.
Shapiro-Ilan, D.I., Raymond, B. 2016. Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes. Evolutionary Applications. 9(3):462-470.
Gumus, A., Karagoz, M., Shapiro-Ilan, D.I., Hazir, S. 2015. A novel approach to biocontrol: release of live insect hosts pre-infected with entomopathogenic nematodes. Journal of Invertebrate Pathology. 130:56-60.
Lacey, L., Grzywacz, D., Shapiro-Ilan, D.I., Frutos, R., Brownbridge, M., Goettel, M. 2015. Insect pathogens as biological control agents: back to the future. Journal of Invertebrate Pathology. 132:1-41.
Shapiro-Ilan, D.I., Hazir, S., Leite, L. 2015. Viability and virulence of entomopathogenic nematodes exposed to ultraviolet radiation. Journal of Nematology. 47(3):184–189.
Blackburn, D., Crawford, B., Shapiro-Ilan, D.I., Adams, B. 2016. Environmental drivers of trait changes in Photorhabdus luminescens. Biological Control. 92:145-152.
Shapiro-Ilan, D.I., Cottrell, T.E., Mizell, R.F., Horton, D.L. 2016. Efficacy of Steinernema carpocapsae plus fire gel applied as a single spray for control of the lesser peachtree borer, Synanthedon pictipes. Biological Control. 94:33-36.
Dito, D.F., Shapiro-Ilan, D.I., Dunlap, C.A., Behle, R.W., Lewis, E.E. 2016. Enhanced biological control potential of the entomopathogenic nematode, Steinernema carpocapsae, applied with a protective gel formulation. Biocontrol Science and Technology. 26(6):835–848.
Blackburn, D., Shapiro-Ilan, D.I., Adams, B. 2106. Biological control and nutrition: food for thought. Biological Control. 97:131-138.
Sun, Y., Bai, G., Wang, Y., Zhang, Y., Pan, J., Cheng, W., Feng, X., Li, H., Ma, C., Ruan, W., Shapiro-Ilan, D.I. 2016. The impact of Cu, Zn and Cr salts on the relationship between insect and plant parasitic nematodes: a reduction in biocontrol efficacy. Environmental Science and Technology. 107(11):108-115.
Shapiro-Ilan, D.I., Dolinski, C. 2015. Entomopathogenic nematode application technology. In: Campos-Herrera, R., editor. Nematode pathogenesis of insects and other pests - ecology and applied technologies for sustainable plant and crop protection. Springer International Publishing. p. 231-534.
Dolinski, C., Shapiro-Ilan, D.I., Lewis, E.E. 2015. Insect cadaver applications: pros and cons. In: Campos-Herrera, R., editor. Nematode pathogenesis of insects and other pests - ecology and applied technologies for sustainable plant and crop protection. Springer International Publishing. p. 207-229.
Tillman, P.G., Khrimian, A., Cottrell, T.E., Mizell, R.F., Johnson, W.C. 2015. Trap cropping systems and a physical barrier for suppression of stink bugs (Heteroptera: Pentatomidae) in Cotton. Journal of Economic Entomology. doi:10.1093/jee/tov217.
Bock, C.H., Hotchkiss, M.W., Cottrell, T.E., Wood, B.W. 2015. The effect of sample height on spray coverage in mature pecan trees. Plant Disease. 99(7):916-925. https://doi.org/10.1094/PDIS-11-14-1154-RE.
Tillman, P.G., Cottrell, T.E. 2015. Spatial distribution of Chinavia hilaris (Hemiptera:Pentatomidae) in peanut-cotton farmscapes. Journal of Insect Science. 15(1):iev081.
Chen, C., Bock, C.H., Hotchkiss, M.W., Garbelotto, M.M., Cottrell, T.E. 2015. Observation and identification of wood decay fungi from the heartwood of peach tree limbs in central Georgia, USA. European Journal of Plant Pathology. 143(1):11-23.
Kemp, E.A., Cottrell, T.E. 2015. Effect of lures and colors on capture of lady beetles (coleoptera: coccinellidae) in tedders pyramidal traps. Environmental Entomology. 44(5):1395-1406.
