Location: Subtropical Insects and Horticulture Research
Project Number: 6034-22320-007-000-D
Project Type: In-House Appropriated
Start Date: Nov 30, 2020
End Date: Nov 29, 2025
Objective:
Objective 1: Investigate biological control and ecological interactions of invasive pests of subtropical orchard crops (especially citrus) with their natural enemies, including signaler compounds that influence pest and natural enemy behaviors, and use this information to develop biologically based pest control strategies.
Sub-objective 1a: Identify plant species that can function as nectar sources or as banker plants (= ‘conservation plants’) to support the natural enemies of ACP in commercial citrus groves and nearby residential areas.
Sub-objective 1b: Determine whether the addition of conservation plants to a target landscape results in increased numbers of natural enemies with a concomitant decrease in ACP and, if so, determine if this effect decreases as a function of distance between conservation plants and citrus trees.
Sub-objective 1c: Perform scale-up of conservation plant arrays for use in citrus groves and evaluate their effectiveness in reducing ACP populations.
Sub-objective 1d: Determine whether plant signaler compounds can be used to: 1) increase recruitment of D. citri natural enemies to citrus; and, 2) influence ACP settling on citrus shoots.
Objective 2: Identify structural, physiological, molecular and chemical aspects of the Asian citrus psyllid and its hosts that can be used in the development of novel interdiction strategies such as feeding disruptors and peptide inhibitors of disease transmission that can be deployed either through biotechnology or exogenous application.
Sub-objective 2a: Screen dsRNAs in silico.
Sub-objective 2b: Identify interdiction molecules that can be expressed in transgenic or PHACT adapted plants for controlling hemipteran insects and their transmitted diseases.
Objective 3: Develop delivery methods to control ACP and HLB using approaches such as biotechnology, optimal chemical formulation, plant infusion, and attract and kill devices.
Sub-objective 3a: Develop direct delivery strategies for RNAi inducing and peptide interdiction molecules.
Sub-objective 3b: Development of transgenic citrus with increased resistance to hemipteran pest insects and/or their vectored diseases.
Sub-objective 3c: Plant-Host Activated-Cell Transplantation (PHACT) as a strategy to induce plant resistance to hemipteran insects and their transmitted diseases.
Sub-objective 3d: Develop Attract and Kill (AK) devices that will effectively suppress ACP populations in citrus groves and residential citrus. The devices will be capable of being charged with soft pesticides, entomopathogens or other killing agents. They will attract and manipulate psyllids using a combination of sensory stimulants and attractants.
Approach:
Orchard crops, a major contributor to the U.S. agriculture industry, are long-lived trees that are threatened by the continuous invasion of exotic pests and the pathogens they transmit. This project’s focus is to increase the sustainability of U.S. orchard crops by reducing economic losses to invasive pests and pathogens. Current pest management practices rely on broad-spectrum pesticides, which are problematic because of their adverse effects on the health of humans, beneficial organisms, and the environment. Reliance on pesticides promotes pesticide resistance in the targeted insects. Thus, there is a need for novel tools and alternative control methods. The biotechnology and biocontrol methods proposed here complement existing IPM strategies and will lead to sustainable solutions for insect vectors of crop pathogens. The project will focus on the citrus/Asian citrus psyllid/Candidatus Liberibacter asiaticus crop/pest/pathosystem. Candidatus Liberibacter asiaticus (CLas) is the presumed causal agent of Huanglongbing (HLB), also known as citrus greening, a fatal disease that threatens citrus production worldwide. CLas is vectored only by the Asian citrus psyllid (ACP) (Diaphorina citri), a phloem feeding hemipteran restricted to Citrus and related genera. The objectives of the project are to develop: 1) Sustainable, biologically-based pest control strategies for area-wide management of HLB-ACP; 2) Interdiction molecules, with a focus on RNAi inducing molecules and bioactive peptides, that block key pathosystem processes; and, 3) Novel delivery methods for improved and effective uptake of interdiction molecules, killing agents, and entomopathogens to control ACP and HLB. The deliverables of this research will be sustainable management strategies that will allow citrus to remain an economically viable commodity in the presence of HLB. These approaches are also broadly applicable to a range of subtropical orchard crops.
