Progress 09/15/23 to 09/14/24
Outputs
Target Audience:Target audiences include: Commercial agricultural growers managing pest-affected crops, particularly citrus growers dealing with disease vectors and invasive pests Nursery operators and greenhouse managers seeking sustainable pest control solutions Agricultural researchers and professionals developing integrated pest management strategies Regulatory and pest control organizations (e.g., Alliance of Pest Control Districts, California Department of Food and Agriculture) implementing pest management policies Agricultural technology companies developing pest monitoring and control solutions Extension specialists and educators serving farming communities Small-scale farmers and traditionally underserved agricultural communities seeking cost-effective pest management alternatives The project's outreach efforts through conferences, consultations, and publications have reached stakeholders across multiple agricultural sectors, with emphasis on regions significantly impacted by pest-related crop losses. Knowledge transfer has focused on practical implementation of new technologies for sustainable pest management. Changes/Problems:Several challenges were encountered during the project execution: Major problems Insect behavior study delay A major setback occurred with the unexpected passing of the postdoctoral fellow in Dr. Stelinski's laboratory, David Olabiyi. This delayed laboratory behavioral evaluation work by approximately six months, consequently pushing field testing implementation to late summer 2024, coinciding with the original project completion date. Minor and technical problems Insect behavior field study delay A device operating in the orchard has been damaged by the hurricane Mlton. The device had to be repaired delaying field study by approximately a month. Two consecutive hurricanes that impacted the state of Florida, have caused other significant experiemental challenges leading to a pause of the field testing. Technical challenges in materials development Early attempts to use gravimetry for assessing volatile release proved unreliable due to inadequate balance precision for detecting 1-10 mg mass differences. This limitation was addressed by switching to PDMS absorbers with GC-MS analysis, which provided higher sensitivity and better quantification of low evaporation rates, though at lower throughput. Material durability issues The graphene composites exhibited fragility during handling and integration into prototype devices. Two specific issues emerged: Cracking during manipulation and transfer Structural failure at higher operating voltages/temperatures To address these challenges: Investigation of composite properties revealed critical relationships between synthesis conditions and performance. With high DVB content, top* sections reached 120°C while middle portions achieved 160°C without failure. Bottom* sections reaching 180°C showed occasional cracking, correlating with higher graphene content (2.45% vs 1.92%). Composite cracking at higher operating voltages was addressed through multiple approaches. The addition of 10% n-butyl acrylate reduced brittleness, while optimization of crosslinker content improved stability. Implementation of microemulsion needle techniques achieved more uniform structure. These improvements enabled reliable operation at up to 180°C with 24.4V potential. Background emission control Initial testing revealed unwanted background emissions of polystyrene-related compounds. This issue was resolved through implementation of a 150°C vacuum baking step, effectively removing these interfering compounds. Thermal management High-voltage testing (>30V) revealed critical thermal stability thresholds: Bottom samples showed lower resistance and reached higher temperatures Samples with >2.45% graphene content exhibited increased failure rates Temperature non-uniformity led to localized damage These issues were addressed through multiple complementary approaches. Thermal management protocols were improved by transitioning from DC to pulsed voltage operation at 1-10kHz, while implementing comprehensive temperature monitoring using both thermocouples and thermal imaging. We developed an automated testing scripts for consistent thermal profiling, established section-specific voltage limits based on graphene content, and integrated feedback-controlled heating cycles. Graphene content was optimized through systematic evaluation of different percentages, ranging from 1.92% to 2.45%. Studies identified optimal content below 2% for thermal stability, leading to standardized mixing protocols ensuring uniform distribution. Quality control measures were implemented for batch consistency, with detailed correlation of graphene content to electrical resistance and heating profiles. Composite geometry underwent significant modifications, starting with redesigned electrical contact placement to minimize hot spots. Precision milling was introduced for uniform sample preparation, while the geometry was optimized for enhanced capillary action for better wicking. We implemented standardized cutting protocols to maintain sample uniformity. These comprehensive modifications significantly improved device reliability and operational consistency, enabling sustained operation within the optimal temperature range of 80-160°C, essential for controlled volatile release without material degradation. Technical challenges did not affect the timeline, fundamentally alter the research objectives or compromise the quality of results. However, the passing severely disrupted operation of Stelinski's laboratory and significantly delayed field testing. The extension of the project duration period was required to complete the proposed insect behavior testing and validation work. *Note: "Top" and "Bottom" refers to the sections of the graphene composite unit that form at upper and lower portions of the reaction container, correspondingly. What opportunities for training and professional development has the project provided?This project provided extensive training opportunities through its collaborative, multi-laboratory and multi-institutional framework. Graduate students developed expertise across several disciplines including materials synthesis, analytical chemistry, electrical engineering, and behavioral ecology. Working at the intersection of these fields pushed students beyond their core disciplines, preparing them for careers requiring broad technical knowledge. Bi-weekly project meetings became a great opportunity for professional development. Students presented their latest findings to colleagues from different specialties, learning to communicate complex ideas to diverse audiences. These meetings fostered valuable cross-pollination of ideas, with discussions resulting in "out-of-the-box" ideas. The collaborative nature between different laboratories in UConn and between UConn and UF exposed students to different research environments and approaches. Students gained practical experience transitioning laboratory discoveries into field applications - a valuable skill rarely developed in traditional academic settings. Students also engaged in discussions of technology commercialization, learning about intellectual property protection and industry partnerships. The project further supported development of mentorship skills, with senior graduate students guiding newer team members and undergraduate researchers. Leadership experience came through coordinating experiments across laboratories and managing timelines for collaborative deliverables. Throughout the project, students developed proficiency in professional communication through manuscript preparation, technical documentation, and presentations to diverse audiences - from fellow scientists to agricultural stakeholders. How have the results been disseminated to communities of interest?Research findings have been disseminated through multiple channels: Academic Conferences International Research Conference on Huanglongbing VII (March 2024, Riverside, CA) National Conference on Citrus Nurseries (November 2024, Exeter, CA) Industry Workshops and Extension Events Citrus Expo, Tampa FL (August 2023) - Several hundred attendees Southwest Florida Research Center Citrus Workshop (April 2023) - 55 attendees UF/IFAS Citrus Insect Workshop, Lake Alfred FL (January 2023) Regular technical updates through extension networks Stakeholder Engagement Ongoing collaboration with Alliance of Pest Control Districts Technical demonstrations for California Department of Food and Agriculture Discussions with EcoData Technology on implementation Direct grower consultations and field demonstrations Government Agency Collaboration CDFA partnership for expanded field trials Proposed large-scale deployment with Citrus Research Board Development of regulatory guidelines Commercial Development Formation of GreenScent Technologies Inc. Four patent applications filed Industry partnerships in development Economic viability analysis completed Extension Resources NIFA Emergency Citrus Disease Research reports Science for Citrus Health website updates Implementation guides and technical documentation Regular stakeholder bulletins The project maintains active engagement with grower communities through multiple communication channels while developing commercial partnerships for technology deployment. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1: The project established optimized protocols for manufacturing graphene-based desorption units through systematic exploration of synthesis parameters. The core synthesis process combines sovent, styrene monomer, divinyl benzene crosslinker, graphite, and azobisisobutyronitrile initiator, followed by controlled polymerization at 60-70°C and subsequent drying. Different graphite flake sizes (1μm, 10μm, 50μm) were evaluated to optimize porosity, with comprehensive characterization using gravimetric and thermogravimetric analysis. Contact angle studies demonstrated spontaneous spreading and absorption of compounds that are used as attractant VOCs on graphene surfaces. Both styrene and acrylate-based composites were developed to accommodate diverse volatile compounds. The acrylate-based materials showed larger emulsion sphere sizes while maintaining desirable open-cell foam structure. Extensive testing revealed optimal polymer compositions for different target compounds, particularly for hydrophilic materials like formic and acetic acids. An approach of uniformly and precisely shaping the composite units with laser cutter as well as the ways to precisely soldering leads have been developed through trial and error. Objective 2: Two prototype designs were developed. The initial 6-channel unit served as a comprehensive testing platform, while a streamlined 3-channel version was optimized for field deployment, reducing manufacturing complexity by over 50%. As shown in Objective 4, simple mixes exhibited high attraction efficacy, making larger channel numbers previosulsy thought necessary, excessive. Efforts then focused on minimizing prototype manufacturing cost to accelerate adoption. Both designs incorporate individual chamber control, mixing chambers, and directional volatile delivery systems. The units operate autonomously using solar power (20W, 12V panel) with battery backup, controlled via microcontroller and custom-designed boost converter. Testing revealed stable operation across frequencies from 1-10kHz. Custom PCB design incorporated protection circuitry and feedback mechanisms for consistent performance under varying conditions. Objective 3: Laboratory testing validated device performance through GC-MS analysis of volatile mixtures at biologically-relevant concentrations, demonstrating reproducible and controllable release profiles. Headspace analysis revealed relationships between applied voltage, temperature, and release rates, enabling parameter optimization for different compound classes. We found that applying square waveform at the same voltage (e.g. alternating 0 and 20V), as opposed to DC voltage allowed to maintain or even increase release efficiency, while decreasing composite's temperature. Optimizing waveform frequency (optimal value was found to be at and around 1000Hz) lead to several-fold increased release, while reducing operation temperature down to ~60C or lower. We attribute this effect to matching of the timescale of molecular desorbtion event off the graphene surface. Overall, we demonstrated that the system posess exceptional control over mixture composition, with selective component activation and minimal cross-contamination. Background emissions were minimal after conditioning, and release profiles maintained stability over extended periods. The system showed particular effectiveness with terpenes and organic acids, compounds of biological interest, maintaining consistent release ratios. Objective 4: Behavioral response in laboratory setting testing utilized a T-maze olfactometer system enabling simultaneous evaluation of four insects, significantly increasing experimental throughput. The quantitative methodology eliminated positional bias through systematic control arm alternation, generating robust data through testing of at least 150 D. citri adults per treatment combination, with five replications of 30 insects each. Multiple known attractive VOCs and their blends have been systematically evaluated: • Individual compounds (methyl salicylate, gamma-terpinene, organic acids) • Binary and ternary mixtures with optimized ratios • Essential oils and complex natural extracts • Competitive assays against authentic citrus volatiles • Temporal stability of behavioral responses • Dose-response relationships • Synergistic effects between components Testing revealed remarkably high attractiveness for volatile blends generated by the graphene-based device. Most notably, a simple binary mixture of acetic and formic acids is one of formulations that matched the attractiveness of young citrus flush (the most potent known attractant for ACP). This unexpected finding suggests high promise for practical applications of the graphene composite-based release technology, as these devics can utilize dramatically simplified attractant formulations rather than complex multi-component blends previously thought necessary. The achievement of citrus-flush-level attraction using common, inexpensive organic acids is particularly advantageous for field implementation. The device also has been tested for repellent capabilities. When releasing fir oil, primarily comprised of sesquiterpenes like alpha-pinene, the system completely suppressed ACP attraction to citrus flush. This established complete control over ACP behavior, from maximum attraction to total repulsion, enabling potential push-pull deployment strategies in field applications. The superior performance compared to traditional wick-based methods likely stems from several key factors. Compared to passive release, the device achieves more efficient dispersal, creating greater gas-phase concentrations leading to more pronounced behavioral response. On the other hand, compared to release from heated diffusers, graphene-based release allows operating below volatile boiling points, thus preventing degradation and formation of potentially repellent byproducts. Additionally, near-ambient release temperatures may better approximate natural volatile emission patterns that insects have evolved to detect. Statistical analysis using Chi-square tests confirmed multiple synthetic blends achieved attraction rates statistically indistinguishable from natural citrus flush. However, the release device allows to create higher concentration of the attractive blend(s) to competitively attract insect away from the tree. The reproducibility and robustness of these behavioral responses were validated across multiple insect populations and environmental conditions. The demonstrated effectiveness of simple volatile blends, combined with the device's ability to generate precise ratios, suggests potential for developing highly cost-effective, field-practical attractant formulations. Objective 5: Field testing commenced in commercial citrus groves with mixed plantings of 4-year-old bearing (2.5 m³ canopy volume) and 1.5-year-old non-bearing (1 m³ canopy volume) trees. The experimental design includes six replicate deployments with paired controls, monitored weekly for psyllid captures. Devices are arranged with 2.4 m spacing and 18 m between treatments. The field tests are currently ongoing. Initial results demonstrate successful autonomous operation under field conditions with effective psyllid attraction. Cost analysis indicates significant advantages over conventional methods (~0.2 cents per acre per month versus $28-62 per acre per application for pesticides). The patent application has been initiated. A company, GreenScent Technologies Inc. has been formed to commercialize the technology. Given positive outcomes for the ongoing field trial, the technology will furnish practical, cost-effective solutions for ACP control, with potential applications extending to other agricultural pests such as Drosophila suzukii and aphids.
Publications
- Type:
Peer Reviewed Journal Articles
Status:
Published
Year Published:
2024
Citation:
A. Aksenov, A., Blacutt, A., Ginnan, N. et al. Spatial chemistry of citrus reveals molecules bactericidal to Candidatus Liberibacter asiaticus. Sci Rep 14, 20306 (2024). https://doi.org/10.1038/s41598-024-70499-z
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Progress 09/15/22 to 09/14/23
Outputs
Target Audience:Several meetings were attended where citrus production personnel were informed about current pest management practices, including emerging tools from this project for possible future use. In 2023, 2 extension presentations were given to groups of growers, production managers, or industry personnel in Florida. This includes presentations delivered at the Southwest Research and Education Center Citrus Workshop, and the Citrus Expo, where growers were informed about managing psyllids with alternative approaches, such as attract-&-kill and repellents. In 2023, development of the web site, "Science for Citrus Health" continued. We held monthly meetings to organize information and update the website. During the last quarter we published an information flier about the Science for Citrus health website on the California Research Board E-News mailer and the Florida Citrus Industry magazine newsletter to increase grower traffic to the site. We also published several new snapshots on the website site. Changes/Problems:No major changes were made. Several problems were encountered during the course of the project: At the early stages of the project gravimetry was used to assess volatiles release. However, it was found that the high precision balance used could not reliably distinguish small mass differences of 1-10 mg, and the readings fluctuated substantially during experiments. To circumvent this issue, we decided to switch from gravimetry to measure volatiles release directly by sampling headspace with PDMS absorbers, followed by analysis with GC/MS. Although lower throughput, because GC/MS is a highly sensitive technique, we could accurately measure the small amounts of volatile compounds collected and significantly improve consistency to reliably quantify the low evaporation rates during our experiments. Overall, the gravimetry approach was inadequate for our experiments due to insufficient precision at the necessary scale. While analyzing the VOC compounds releasing from the composites, it was found that polystyrene and other related compounds were also present in the released volatile mix (impurities from the composite manufacturing process). The baking the composites in the vacuum oven at 150°C prior to any experimentation was found to be essential to remove the backgorund. The graphene composites were found to be rather fragile. This made handling and transferring the composites difficult, especially when integrating them into the prototype device we fabricated. Because the composites were prone to cracking and breaking when manipulated, care needed to be taken to prevent damage. As the material is very cheap, we have fabricated multiple replicate composite pieces to provide spares in case there is any damage during device handling and testing. Going forward, we will explore increasing the amount of polymer support to improve make composite sturdier. To characterize the evaporation behavior of volatile compounds from the graphene composites, we initially tested a wide voltage range, from 0V up to 60V. However, we found that at higher voltages and the associated temperature increases, the evaporation rates became highly variable and the composites themselves started to crack and ignite. Going forward, we have limited the voltages used in experiments to 20-24V. Within this lower range, we obtained good evaporation rates with reproducible quantitation. It is expected that the morphology of the composite evolves along the height of the reaction vessel, thus we aim to determine the portion with optimal properties and greatest reproducibility of properties. Thermal tests were conducted on 30 different graphene samples to determine if they can be mass produced with consistent thermal characteristics. The samples of graphene are divided into three categories: top, middle, and bottom, corresponding to the synthesis conditions. These portions were then tested at three different voltage levels (10V, 20V, 30V) to see if they have the same thermal behavior. The resistance results are shown in Fig. 7. Bottom samples tend to have lower resistances than the top and middle. This difference is translated in their thermal characteristics as shown in Figures 1, 2 and 3. Figure 1. Thermal test at 10V Figure 2. Thermal test at 20V Figure 3. Thermal test at 30V The samples with lower resistance have higher steady state temperatures are therefore more prone to breaking. We have further investigated the issue of composite cracking at higher voltages. The samples were tested at four different voltage levels: 10V, 20V, 30V and 40V; when the voltage is applied the samples will heat up until they reach a thermal steady state for that voltage level. From Figure 4, it can be seen that the steady state temperature of Sample 1 for 10V is 45 °C, at 20V is 95 °C, at 30V is 155 °C and at 40V thermal steady state is not reached as the sample cracked. Other samples had similar thermal steady state characteristics. We found that after reaching a certain temperature (180 °C and above) some of the composite pieces would start to smoke and then they would crack. Surprisingly, some of the samples would "heal" themselves after getting cold i.e., the cracks will disappear as seen in Figures 4-8. As expected, it was found that samples with a lower resistance tend to reach higher temperatures for the same voltage level which makes them more prone to cracking than others. This information is essential to correctly select operation regime for the use of composite. Figure 4. Temperature test on 30mm long graphene samples. Figure 5. 30mm graphene samples crack when hot and when cold. Figure 6. Temperature test on 20mm long graphene samples. Figure 7. Hot graphene samples after cracking occurs. Figure 8. Cold graphene samples after cracking occurs. An example of the testing results for the material behaviors is shown in Table 1. Samples 6 and 8 that cracked and "healed" showed very similar resistance before and after the tests. Whereas samples 9 and 12 that did not "heal" had a much higher resistance after the tests. All other samples showed a very similar resistance before and after thermal tests. Table 1. Resistance results for the different graphene sample lengths. What opportunities for training and professional development has the project provided?This project has provided valuable training and professional development for multiple early-career researchers. Six graduate students and one postdoctoral researcher have been involved in the project across the two labs. Their participation has given them hands-on experience in areas including nanocomposite fabrication, experimental design, operating analytical instrumentation, data analysis, and troubleshooting technical challenges. Undergraduate researchers, primarily from the Aksenov lab, have also gained research skills by assisting with experiments like gravimetry testing. The three PIs have held biweekly meetings with all students and postdocs working on the project. These meetings facilitate sharing of findings, discussion of issues, and tracking of progress. They provide an important mentoring opportunity for the trainees to develop skills in scientific communication, presentation, and collaboration. How have the results been disseminated to communities of interest?Several meetings were attended where citrus production personnel were informed about current pest management practices, including emerging tools from this project for possible future use. In 2023, 2 extension presentations were given to groups of growers, production managers, or industry personnel in Florida. This includes presentations delivered at the Southwest Research and Education Center Citrus Workshop, and the Citrus Expo, where growers were informed about managing psyllids with alternative approaches, such as attract-&-kill and repellents. In 2023, development of the web site, "Science for Citrus Health" continued. We held monthly meetings to organize information and update the website. During the last quarter we published an information flier about the Science for Citrus health website on the California Research Board E-News mailer and the Florida Citrus Industry magazine newsletter to increase grower traffic to the site. We also published several new snapshots on the website site. An abstract has been submitted to the IRCHLB VII conference: "Generation of an optimally attractive scent for Asian Citrus Psyllid (ACP) biocontrol" What do you plan to do during the next reporting period to accomplish the goals?The next key areas of focus will be: Continuation of ACP bioassyas with the first generation prototype. Testing of the release of volatiles using pulsing/waveform instead of DC. Assemply of the second generation of the prototype. The next generation of the device will be multiplexed to up to 50 individual compounds. Also, individual control of the release level will be added. Finally, the possibility of the non-DC releases will be included, based on the upcoming testing of compound release by applying waveforms. The next generation of the device is expected to be further improved to reduce power consumption by controlling heating via use of voltage pulsing. Testing, benchmarking and validation of the second generation prototype both to establish the parameters of operation, and assess the volatilome generation including reproducibility, stability, and accuracy. Once the second generation device is validated, commense bioassays using the second generation device. Preliminary testing of the second generation device in orchard setting.
Impacts
What was accomplished under these goals?
Objective 1. Synthesis of the graphene based polystyrene composite An optimized synthesis protocol has been established. The composites are then cut in the required shape and copper wire are attached to supply the voltage. The synthesis protocol has also been modified for generating materials with varying porosity. A first-pass gravimetric testing has been conducted to confirm the release of volatiles from synthetically produced materials. TGA studies have been conducted to determine the volatility of the of the VOC's with graphene composites. This information is used to guide the design of the release module and the operation conditions. In order to enable the wicking action, the material needs to be designed to be wettable by the compound it disperses. The representative terpenes have been explored for the wetting behavior of the composite; the wetting is assessed by measuring contact angle. The contact angle of limolene, geranyl acetone and citral were studied on the films, and it was observed that the VOC's spread and absorbed on the graphene surface spontaneously. In order to optimize release of compounds with different polarity, a set of different composite formulations have been developed. In these cases, the supporting polymer is altered to manipulate the properties of the material. In particular, for the release of hydrophilic materials (in particular formic and acetic acids), a polar acrylate-based polymer has been tested. Sphere size analysis was conducted, it was observed that the emulsion sphere of the acrylate contained composite is bigger than the styrene-based composite. In all the cases it produced open cell foam composite Objective 2. We have conducted extensive testing of the release behaviors for various compounds to calibrate the release conditions for manipulation of composition of the released mix. Both liquids and solids were tested. The compounds with potential attractant properties to the Asian Citrus Psyllid (ACP) vector, were added individually (200-400 μL) onto graphene composites, which were then connected to a DC power supply. In order to measure the release efficiency, gas chromatography-mass spectrometry was used (Agilent 7200 QTOF). The polymethyl siloxane material (PDMS) was used to sample the released VOCs and measure gas-phase abundance for each compound (Fig. 1). An example of datac is shown on (Fig. 2). We have determined that a "trigger" voltage, once reached, leads to rapid release of the compound, and the voltage below this value could be changed to fine-tune the gas-phase concentration. Figure 1: Volattiles release sampling using PDMS Figure 2: Volatiles release trends as a function of applied voltage Impedance Characterization of graphene samples We have further began testing the behaviors of the composite material to establish optimal heating regime other than simple DC. To better understand the material properties at higher frequencies, different graphene samples were tested to characterize their impedance with respect to frequency using the Bode100 R1 VNA with B-WIC. Fig. 3 shows setup for impedance characterization of graphene samples. Figure 3. Test setup for impedance characterization of graphene samples It was noted that the impedances change from sample to sample, but the overall shape of the frequency response remains the same. The samples behave like resistors until 100kHz, after that point it behaves more like a capacitor. Fig. 4 shows the impedance plot versus frequency. Figure 4. Impedance magnitude with respect to frequency of a graphene sample Thermal Testing of Graphene Samples Graphene samples of different lengths were tested to obtain their thermal characteristics under different voltage conditions. The setup used to carry out the test is shown in Fig.5. A variable DC supply, a multimeter, a thermocouple measuring device, and a thermal camera were used. Figure 5. Test setup. Objective 3. First Prototype Design and Implementation A prototype was designed and built using a 3D printer. It consists of 6 chambers, in each of these chambers 1 graphene sample is put inside a vial that contains different compounds (such as: limonene, geranyl acetone, acetic acid etc.). The graphene samples are connected to a 0-24V variable DC power supply. The supply to each sample can be turned on separately using a switch. At the very top, a fan and an exhaust are placed to blow air out of the mixing chamber. The individual parts of the prototype that were designed and printed are shown in Fig. 6. Figure 6. Parts of the prototype The circuit diagram that was used to control the switches and therefore when a sample can be turned ON or OFF is shown in Fig. 7. Figure 7. Circuit diagram used to control the switches. The first prototype was constructed, and the final product is shown in Fig. 8. Figure 8. First prototype. The prototype validation. The first prototype device was validated to confirm controlled release of VOCs and the ability to control the mixture composition (Fig. 13). We have tested a variety of compounds including limonene, geranylacetone, Tridecane, Acetic Acid and Formic acid, to represent typical VOCs that are expected to be comprising ACP lure. The device performance is highly reproducible (Fig. 9). Figure 9. GC/MS trace for volatile mixtures produced by the prototype. Top panel: an example of chromatogram showing release of three compounds that are turned on (the minor peak adjacent to the peak of D-limonene is determined to be an impurity of L-limonene). The bottom panel: consistency of the volatile profile release is evident by reproducible profile run-to-run. Turning off all of the release modules (blank) results in no volatiles, indicating absence of the "dark" emission. Objective 4. The first generation prototype device has been shipped to the testing site at the UF CREC facility. Prior to receiving the device, we have completed development and calibration of olfactometer bioassays for high throughput data collection. We developed an innovative olfactometer system where we can simultaneously test 4 individual insects in separate tubes. Once the volatiles are sent to the tubes, the distance moved by each psyllid is recorded. The attractiveness of a volatile treatment is determined by the distance moved by each psyllid due to the tested odor compared to a control (solvent only or clean air). In contrast to conventional olfactometer methods, the data recorded will be quantitative rather than qualitative, which facilitates comparison of volatile attractiveness (potency). We have also established a culture of insects that will be used in bioassays. A susceptible laboratory population of Asian citrus psyllid, Diaphorina citri, is being reared in a greenhouse at the University of Florida, Citrus Research and Education Center, Lake Alfred, FL. Adult D. citri from field populations were collected from commercial citrus groves in Wauchula, Vero Beach, Clermont and Odessa, FL. The cultures are maintained on sweet orange (Citrus sinensis (L) (Osbeck) in a greenhouse at 27 ± 1ºC, with 60-65% relative humidity and a 14:10 h (light: dark) photoperiod. The citrus plants were purchased from a local nursery (Dundee, FL). In our calibration assays, we have confirmed no positional bias in our olfactometer set up and that we can reliably demonstrate behavioral response of adult D. citri to the volatiles emanating from their authentic host plants.
Publications
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