Grant Information
| Knowledge Area | Subject of Investigation | Field of Science | Percent |
|---|---|---|---|
| 211 - Insects, Mites, and Other Arthropods Affecting Plants | 999 - Citrus, general/other | 1130 - Entomology and acarology | 100% |
Pest management in Florida citrus has been significantly transformed since 2005 due to the introduction of citrus greening disease (huanglongbing). The insect vector of greening, the Asian citrus psyllid (ACP, Diaphorina citri), was first detected in Florida in 1998, and rapidly established throughout the state. There is no current cure for citrus greening and the impact of the disease on Florida citrus production has been devastating. The disease limits citrus production by reducing yield, decreasing fruit quality, and can eventually kill trees. Since 2012, there has been a $418 million comnined annual loss of revenue to growers due to this disease alone, and orange production in 2018 was at an 80% decrease since pre-infection yields. Citrus canker (Xanthomonas axonopodis pv. citri) is another severe disease currently affecting the Florida citrus industry. Like greening, canker is closely associated with an insect pest, the citrus leafminer (CLM, Phyllocnistis citrella), present in Florida since 1993. While not a true vector of citrus canker, CLM larvae damage young citrus leaves when feeding, making them highly susceptible to canker infection. The threat of these two diseases has required much more intense chemical pest management in Florida citrus than in previous industry history. This project addresses the scientific evaluation and delivery of current and new technologies for management of ACP, CLM, and other citrus pests, as well as development and dissemination of new integrated pest management tactics that are compatible with the current unique needs of the Florida citrus industry. As these technologies are evaluated, I disseminate pest management recommendations to the Florida citrus industry based on the outcomes of my research program and those of my colleagues. The intended impact is to add new technologies and products into Florida citrus pest management that render citriculture more sustainable, productive, and economical.
?Sequence of Activities and RolesDescription of ActivityMeasurable outcome whereby progress can be evaluatedTimeline/Annual MilestonesObjective 1. Devise and validate tactics for improving impact of biological control on ACP.Compare the effectiveness of biological control in commercial orchards in FL and TX determine if abiotic factors or management practices influence effectiveness. Use this knowledge to improve the effect of biological control.Evaluate the level of biological control in urban citrus and abandoned orchards to determine its effectiveness for these situations.Improve understanding of the release of biocontrol agents for ACP.Manipulate abiotic factors (insecticide use) to facilitate effectiveness of biological control.Determine the value of biological control in urban areas and potentially harness the impact for agricultural areas.Render biological control more compatible with use of insecticides to manage ACP.Improve biological control of ACP under various insecticide spray schedules by reducing impact on biological control agents.Optimized use of insecticide sprays during the dormant winter period based on greater understanding of potential alternative hosts for ACP.Years 1-2: Investigate the impact of biological control agents in urban areas and abandoned citrus and what impact this may have on citrus grown in commercial monocultures.Years 1-2: Investigate how levels of ACP biological control may be improved by altering insecticide use and by release of parasitoids.Years 1-2: Initiate monitoring populations of ACP and beneficial insects in conventionally managed, IPM managed, and unmanaged groves.Years 3-4: Complete field investigation on improving biological control by modifying insecticide use.Objective 2. Monitor and manage insecticide resistance at local and regional scales.(Years 1-2)Develop and implement effective rotation schedules based on understanding of the mechanisms governing resistance for ACP.Improve insecticide spray schedules based on a better understanding of need.Develop a protocol for ACP management in areas where neonicotinoid use is failing.Maintain or reduce insecticide resistance levels by developing optimized insecticide rotation schedules for growers that are based on best understanding of resistance mechanisms.Delivery of new insecticide rotation schedules where ACP cannot be controlled with soil applied neonicotinoids.Years 1-3: Initiate field experiment investigating insecticide resistance reversal in plots treated with soil-applied neonicotinoids.Years 3-4: Complete field investigation on reversing insecticide resistanceObjective 3. Develop IPM based management recommendations that incorporate findings regarding (a) behavioral management, (b) insecticide resistance, (c) long-term economic impacts.Implement new insecticide rotation schedules based on fundamental data of ACP resistance mechanisms.Modify insecticide applications schedules based on whether re-inoculation is an important factor and whether transmission can be interrupted by insecticide alternatives.Develop cost budgets and estimate long-term grower returns for ACP control in all three states before and after optimization of the area-wide model for ACP and HLB management.Extend findings from this project to citrus growers in FL and TX with additional knowledge transfer to CA.Update project website with results of pre-and post surveys and results from IPM implementation trials.Conduct annual meeting with Advisory Panel.Reduced use of insecticides benefits the economics of citrus production.Reduced use of insecticides increases activity of biological control agents.Growers receive a plan for optimized ACP management that includes the action of biological control agents and reduces the possibility of insecticide resistance development.Extension documents, online information, and training courses are developed to extend new information to growers.Years 4-5: Implement new insecticide rotation schedules where ACP cannot be controlled with soil applied neonicotinoids.Year 5: Modify insecticide applications schedules based on reduced re-inoculation with tree netting and enhanced biological control (Objective 1) and integrate this program with new insecticide rotations being investigated in Objective 3.Years 4-5: Build economic model and novel method for growing citrus in the face of HLB based on integration of IPM for ACP management.Years 4-5: Implementation of refined IPM for ACP and HLB management causing greater sustainability and profit of citrus production in FL and TX with knowledge transfer to CA.
Target Audience
Citrus and avocado growers and industries related to these specialty crops.
Changes / Problems
None.
Training & Professional Development
One of my PhD students, Benita Shrestha, who worked on interactions of Asian citrus psyllid with natural enemies successfully graduated in December of 2021. Also, one of the MS students I co-advised with L. Diepenbrock successfully graduated in September of 2021. Currently, I am co-advising one PhD student (David Olabiyi) and one Masters students (Lourdes Perez) with Lauren Diepenbrock. David is working on aspects of Lebbeck mealybug biology and management. Lourdes is working on repellents for Asian citrus psyllid. I also serve on the PhD committees of Gagandeep Kaur (Entomology- GCREC), Emilie Demard (Entomology-IRREC), Mohamed Ali (Entomology-SWREC), Derrick Conover (Entomology-NFREC), Nicholas Johnston (Entomology-NFREC), and John Ternest (Entomology-Gainesville). In addition, I serve as member on the committee of one entomology Masters student (Rowda Altamimi) at NFREC.
Dissemination Streams
My extension program focuses on development and delivery of statewide educational efforts in citrus pest management with the focus on optimizing the profitability and sustainability of citrus production with the following goals: 1) Changing grower behavior to maintain integrated pest management tactics in citrus under conditions of chronic disease(s) reducing yield and 2) Changing grower behavior to overcome insecticide resistance development. The goals and accomplishments of my extension program are described in depth in the abbreviated T&P packet below. In 2021, I delivered a presentation at the Florida Citrus Show, one presentation at the UF IFAS Florida Citrus Growers' Institute (presented virtually), and one at the Citrus Expo. I also co-organized and presented during a webinar organized by Science for Citrus Health in cooperation with UC Agriculture and Natural Resources. I also presented at the Avocado Laurel Wilt-Ambrosia Beetle Workshop in 2021 and developed a training lecture for the FL Certified Crop Advisor program. By the numbers, in 2021, I developed/presented 6 extension talks to groups of growers, production managers, or industry personnel in Florida and elsewhere. Also, I authored or co-authored one article in Citrus Industry Magazine. I also engaged in several phone call consultations as part of my extension responsibility. I also participated in the revision of three EDIS publications in 2021.
Next Reporting Steps
My 2022 research program will focus on meeting the goals of two existing USDA-SCRI-CDRE projects and one USDA-APHIS-MAC project, which is coming to an end. My intention is to also continue to garner new funding for the lab. Specific areas of current research: Title: Field implementation of an advanced multimodal attract-and-kill device (CAPUT trap) for sustainable management of Asian citrus psyllid. Source: USDA-APHIS-MAC. Purpose: Continue development of attract-&-kill device as a tool for ACP population suppression. Title: Optimal Bt toxins and gene silencing RNAs for management of Asian citrus psyllid to mitigate impact of citrus greening. Source: USDA-NIFA. Purpose: Develop engineered citrus expressing Bt toxin for management of ACP. Combine with RNAi to mitigate resistance development and increase efficacy. Title: Targeting ACP gut to prevent transmission of HLB pathogen. Develop methods and protocols for reducing transmission of the CLas pathogen by the psyllid vector. My role in this project is to develop an extension component. I will be advising 2 graduate students during 2022. I will also serve on committees of 7 other graduate students. I expect that my extension role in the Florida citrus industry will continue at its current pace in both materials produced and impact. I will continue to work with all of the county extension agents focusing on citrus and continue educating growers about my research and the research of my colleagues at CREC, IFAS, and other institutions. I expect that I may be invited to contribute presentations at annual venues, as well as smaller meetings and in-service training. I will continue serving as one of the go-to people regarding psyllid management, psyllid biology/ecology, as well as pyllid control with pesticide alternatives. I will also continue to be one of the go-to entomologists regarding other current insect pests such as the citrus leafminer, Diaprepes root weevil, and Lebbeck mealybug. I have developed a well-known extension role as educator of integrated management strategies, insect ecology, and insecticide resistance. I will continue to distribute new information through publication in appropriate extension outlets such as trade journals or EDIS.
Target Audience
Citrus growers, productions managers, and agrochemical industry related to citriculture.
Changes / Problems
None.
Training & Professional Development
This project has trained 5 post-docs and 4 students. Two post-docs have recently graduated the prpgram.Justin George obtained a GS-13 Research Entomologist position with ARS in Mississippi and Freddy Ibanez began as an assistant professor of plant vector entomology at Texas A&M.
Dissemination Streams
The results have been disseminated though peer reviewed publications, extension publications in population magazines and university-sponsored extension publications. The results were also disseminated through presentations given at grower meetings and workshops. The results have also been disseminated using the internet via the Science for Citrus Health website.
Next Reporting Steps
My 2021 research program will focus on meeting the goals of existing USDA-APHIS-MAC and CRDF funding obtained prior to 2020, as well as, the newly obtained funding from USDA-SCRI-CDRE. My intention is to also continue to garner new funding for the lab. Specific areas of current research: Title: Why spray if you don't need to? Putting the IPM back into citrus IPM by ground truthing spray thresholds. Source: CRDF. Purpose: Implement injury thresholds to determine for need for insecticide applications for ACP. Title: Evaluation of a novel device for releasing volatile repellents against Asian citrus psyllid: optimizing active ingredient and deployment strategies for field-scale use. Source: USDA-APHIS-MAC. Purpose: Continue development of repellent device as a tool for ACP population suppression. Title: Field implementation of an advanced multimodal attract-and-kill device (CAPUT trap) for sustainable management of Asian citrus psyllid. Source: USDA-APHIS-MAC. Purpose: Continue development of attract-&-kill device as a tool for ACP population suppression. Title: Optimal Bt toxins and gene silencing RNAs for management of Asian citrus psyllid to mitigate impact of citrus greening. Source: USDA-NIFA. Purpose: Develop engineered citrus expressing Bt toxin for management of ACP. Combine with RNAi to mitigate resistance development and increase efficacy. <br><br>
<br>What was accomplished under these goals? My research program in 2020 focused primarily on insect and pathogen interactions and pest management in citrus and avocado. We made progress on several fundamental ecology projects; however, most of my research was geared toward practical application. I provide some in depth examples below. A large multi-grant and multi-state project my lab has been coordinating is development of an attract-&-kill device for ACP. This project is coming to its natural end. During the project, we developed two prototypes of a multimodal attract-and-kill device that is three dimensional in shape and includes elements of color, attractant, phagostimulant, UV reflectant and toxicant. All of these cues were optimized individually and then brought together for this device. Ingredients that were identified during the project were incorporated into a yellow slow-release wax (SPLAT) matrix and applied directly on the surface of a yellow cylinder or applied to corrugated plastic card and inserted inside a perforated cylinder. Psyllids landing on the device attempted to feed from the wax matrix, became intoxicated, died and fell from the device. Our laboratory and field experiments showed that the device attracted and killed significantly more adult ACP than ordinary yellow sticky cards and remained fully active over a period of 12 weeks. We have been in conversations with ISCA Technologies regarding commercialization of a product for field use. In avocado, my lab assessed the repellency of methyl salicylate and verbenone to two putative laurel wilt vectors in avocado,Xyleborus volvulusandXyleborus bispinatus, under laboratory conditions. Then, we tested the two chemicals released from SPLAT® with and without low-dose ethanol dispensers for manipulation of ambrosia beetle populations occurring in commercial avocado. The potential active space of repellents was assessed by quantifying beetle catch on traps placed 'close' (~ 5-10 cm) and 'far' (~ 1-1.5 m) away from repellent dispensers. Scolytidid beetle catch was reduced in the field more when plots were treated with verbenone dispensers co-deployed with low-dose ethanol dispensers than when treated with verbenone alone. Beetle diversity was highest near traps in plots where low-dose ethanol lures were deployed. The repellent treatments and ethanol lures significantly altered the species composition of beetles captured in experiment plots. Our results indicate that verbenone co-deployed with ethanol lures holds potential for manipulating ambrosia beetle vectors via push-pull management in avocado. We continue our work on resistance management of ACP, although this project is also slowly winding down. We demonstrated that ACP populations develop high levels of resistance to several of the main modes of action used for their management under continuous selection by label rate applications in cultivated citrus. For example, a high level of resistance occurs following only 3-4 consecutive neonicotinoid sprays and within five egg to adult generations and was associated with subsequent product failure. We also showed that resistance in ACP to declined significantly in the absence of selection pressure under laboratory conditions and when modes of action rotation was implemented after initially selecting for resistance under field conditions. Recovery to a susceptible state under rotation in the field was more rapid than under no selection in the laboratory population. These results suggest that resistance is likely unstable under the field conditions. We proved resistance to several modes of action caries significant fitness consequences in ACP. In effect, our results indicate that careful rotation solves the problem entirely. In my opinion, it would be useful to continue to monitor for resistance as long as insecticides are being used for ACP, because other mechanisms of resistance that are not apparent yet could evolve. Furthermore, failures of rotation occur for various reasons and it would be good to know if those are causing negative effects on ACP management. Consideration should be given regarding whether funding a monitoring program to maintain an up to date knowledge base of current susceptibility levels of ACP populations to insecticides in FL is worth the investment. We have also continued work on pathogen-plant-insect interactions, focusing on HLB. Citrus trees were exposed to either a 'one-time' 7-day Inoculation Access Period (IAP) or 'continuous' IAP for an entire year. We hypothesizeda priorithat those trees exposed to infected vectors for 7-day IAP (assuming 100% transmission) would continue to live and grow with lowCLas titer. In contrast, we expected those trees receiving constant re-inoculations fromCLas-infected ACP over the course of the experiment would develop highCLas titer and consequently succumb to the symptoms of HLB disease much faster. Astonishingly, we observed no difference inCLas titer between plants exposed to infected vectors for 7-day IAP, as compared with plants exposed continuously to a breeding population ofCLas-infected vectors over the course of an entire year of plant infection. Also, the presence/absence of the genomicCLas DNA in mature leaves was associated with intense periods of vegetative flush growth, suggesting that theCLas bacterium is transported through phloem during annual movement of carbon and nitrogen compounds needed for vegetative growth, including transportation from roots to mature leaves. We recently examined the mechanism(s) of immune response inC. sinensisvia accumulation of SA and its metabolites after prolonged feeding by uninfected ACP and determined that herbivory differentially regulated transcription and SA-metabolite accumulation in citrus leaves, depending on duration of insect feeding (Ibanez and Stelinski, 2020; Ibanez et al., 2019). Our results showed a significant upregulation ofBSMT-likeand concurrent downregulation of a methylesterase,MES1-like,in plants that had been exposed to ACP feeding for 150 d. Expression ofBSMT-likewas associated with an increase in methyl salicylate accumulation in mature leaves. Similarly, this outcome was observed for the expression profile ofDMR6-likeand accumulation of 2,3-DHBA (hydroxylated SA metabolite). Therefore, prolonged and uninterrupted exposure of citrus to ACP feeding modulates SA and accumulation of its metabolites in sweet orange. We hypothesized that a threshold [SA] exists inC. sinensisthat modulates the transcriptional regulation of genes involved in immune defenses and that the abnormal level of gene expression and metabolite accumulation under this scenario does not allow the host plant,C. sinensis, to mount a proper immune response (Ibanez et al., 2019). Based on this work, we submitted a proposal to USDA-SCRI-CDRE to elucidate the biological function of a set of genes associated with synthesis of SA and its metabolites and determine how its accumulation in plant tissues modulates SA-dependent immune responses to the pathogen and vector. The long-term goal of this project is to manipulate response ofCitrusto the vector-pathogen interaction to boost host plant defense response against HLB. Unfortunately, the reviewers did not agree that this apporach was critical to solving the HLB problem. <br><br><b>Publications</b><br>