The objective of the project is to evaluate the impact of Asian citrus psyllid (ACP) control programs on non target insects and mites. During this quarter, we monitored populations of ACP and secondary pests such as citrus rust mites, citrus red mite, snow scale, Florida red scale, Chaff scale, citrus leafminer, citrus black and whiteflies, as well as their parasitoids and predators in four large scale experiments designed to test different ACP control programs in commercial citrus in Collier, Lee and Hendry counties. The experiment in Collier county compares (1) Nutritional (2) Insecticides (3) Insecticides + Nutritionals and (4) Untreated. Insecticides currently recommended for ACP control are used when adults exceed 0.2 per tap sample and nutritional products and their application timing follow a program developed by McKinnon Corporation averaging three sprays per year. ACP averaged 0.5, 0.1, 0.05 and 3.6 per tap sample in treatments 1, 2, 3 and 4, respectively. Populations of non targets were generally low except citrus rustmites in June averaging 0.3 and 1 per lens field in untreated and nutritional alone treatments compared to none observed in the samples in insecticidal treatments that used spirotetramat (Movento 16 oz/ac) in May. indicating that insecticides controlled both psyllids and mites. Predatory mites averaged 0.4 per lens field in the insecticide treatment; significantly more than 0.1 or less observed in the other three treatments in June. In a block of ‘Valencia’ in Lee county, ACP averages of 0.07, 0.1 and 0.13 per tap sample were observed in June in plots receiving grower standard sprays, biweekly sprays of 435 oil or untreated check, respectively. Citrus rustmites averaged 0.09 and 4 per lens field in the grower standard and biweekly oil treatments, respectively, significantly less compared to 10 per lens field in the untreated control indicating that both insecticidal and oil sprays reduced ACP and mites. Each of the two experiments in Hendry county, one in a 35 acre block of ‘Early Gold’ and the other in a 16 acre block of ‘Valencia’ include 4 treatments: three spray programs for psyllid, one receiving monthly calendar sprays, two intended to maintain ACP populations below thresholds of 0.2 or 0.7 psyllids per tap sample and an untreated check. The calendar treatment received Diflubenzuron (Micromite) at 6.25 oz per acre in April. In May the entire ‘Early Gold’ block was sprayed with Abamectin (ABBA) at 15 fl oz per acre to control rustmite. At the same time, the calendar treatment in ‘Valencia’ block was sprayed with Spinetoram (Delegate) at 4.5 oz. This product and rate was also used in the calendar treatment of ‘Early Gold’ block in June. Insecticides suppressed ACP and citrus rustmites compared to the untreated control in both blocks. Predatory mite populations were generally low and did not provide significant suppression of citrus rust mites. We found that the predatory mite Amblyseius swirskii provided significant reduction in ACP immatures under controlled conditions. These mites are commercially available and might be useful in reducing psyllids, rust mites, some other mites and additional insecticide sprays in citrus. We also initiated bioassays to evaluate residual effects of some commonly used and new chemistries against predators and parasitoids common in citrus. Two foliar trials involving several treatments of recommended and experimental insecticides to study effects on ACP and non-targets were also initiated. Juan-Blasco, M, J. A. Qureshi, A. Urbaneja and P. A. Stansly. 2012. Predatory mite Amblyseius swirskii (Acari: Phytoseiidae) for biological control of Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae). Florida Entomologist (In press).
Objectives of this project include: 1) scale up production of Tamarixia radiata to levels that will allow better assessment of the potential impact an augmentation program may have on the ACP population and ultimately the spread of HLB, 2) use genetic techniques to identify parasitoids recovered from the field to demonstrate establishment and effectiveness of released strains, and 3) pass on rearing technology to both private and public sectors to encourage production and an adequate supply of these parasitoids into the future. This quarter 46,719, 51,410, 35,203 and 56,706 Tamarixia radiata were produced at DPI, Gainesville by colonies from South China, Pakistan, North Vietnam and the “Florida strain” originally established from Taiwan and South Vietnam. Colony of Florida strain maintained at SWFREC produced an additional 19,000 T. radiata. Wasps from these colonies were used for research, colony maintenance and release in conventional and organic citrus groves in Collier, Lee, Hendry, Lake, Indian River, Hillsborough, St Lucie, Polk, Hardee and Desoto counties. Parasitism averaged 29% (n=246) in April in a release block at SWFREC Collier county compared to 9% (n=196) in control blocks. In May, 17% (n=18) nymphs were parasitized in a sample from the release plot and none (n=89) from the control block. In a commercial block of ‘Valencia’ in Collier county parasitism averaged 17% (n=63) in release plots compared to only 3% (n=36) in control plots. ACP populations in May were low and none were parasitized but in June, 9% of nymphs (n=149) were parasitized in insecticide free plots even without releases but none were parasitized in insecticide treated (n=28) plots. At a location in Lee Co. no parasitoids were recovered from nymphs collected in April from the untreated plots (n=70) or plots treated with biweekly applications of 435 oil (n=202) or grower standard insecticide (n=32) applications in a block of ‘Valencia’ in Lee county. Only 4% nymphs (n=130) were parasitized in samples collected in June from oil-treated plots and none from insecticide treated (n=82) or untreated (n=60) plots. No parasitoids were recovered from 201 nymphs collected in May from plots under calendar sprays or untreated plots in a block of ‘Early Gold’ in Hendry county. Very few nymphs were available at locations in other counties and parasitism rates were low averaging 10% or less. Collaboration continues with OrangeCo where trees in large field cages in Charlotte Co. were trimmed to induce new growth an wasps released at different rates to evaluate effectiveness against ACP. Releases were also made in blocks under soft and hard insecticide programs and results are being evaluated with ACP sentinel plants set out in a regular array. Bioassays at SWFREC of recommended and experimental insecticides against T. radiata were also initiated. A master’s student being paid for by this project has completed a study showing that T. radiata recover quickly from CO2 anaesthesia which can therefore be used to manipulate the wasps and possibly separate them when mixed with ACP in mass rearing colonies. She has written a review of T. radiata biology that will be submitted for publication and begun a study to look at the effect of nymphal densities on parasitization by T. radiata that will help us optimize rearing conditions. A symposium on the role of T. radiata in management of ACP is arranged for upcoming Florida Entomological Society meeting and article was published in Citrus Industry. Qureshi, JA., E. Rohrig and P. Stansly. 2012. Introduction and augmentation of natural enemies for management of Asian citrus psyllid and HLB. Citrus Industry. 93(6): 14-16.
New outbreaks of invasive fruit flies (Diptera: Tephritidae) continue to threaten agriculture world-wide. Establishment of these pests often results in serious economic and environmental consequences associated with quarantine, control, and eradication programs. Early fruit fly detection and eradication in the United States requires deployment of large numbers of traps baited with the highly attractive male specific parapheromone lures trimedlure (TML), cue-lure (C-L), and methyl eugenol (ME) to detect such pests as Mediterranean fruit fly, Ceratitis capitata (Wiedemann), melon fly, Bactrocera cucurbitae (Coquillett), and oriental fruit fly, B. dorsalis (Hendel), respectively. The current study compared the performance of solid single lure cones and plugs in conjunction with DDVP insecticidal strips; liquid lure with naled formulations; and single, double, and triple solid lure wafers impregnated with insecticide. Treatments were placed in AWPM and Jackson traps under Hawaiian climatic conditions in habitats where B. dorsalis, C. capitata, and B. cucurbitae occur together. The overall goal of this study was to develop a more convenient, effective, and safer means to use male lures and insecticides for improved detection and male annihilation of invasive fruit flies. In survey trials near Kona, HI captures of C. capitata, B. cucurbitae, and B. dorsalis with Mallet TMR wafers were equal to those for the standard TML, ME, and C-L traps used in Florida and California. A solid Mallet TMR wafer is more convenient to handle, safer, and may be used in place of several individual lure and trap systems, potentially reducing costs of large survey and detection programs in Florida and California, and male annihilation programs in Hawaii. With confirmatory trials completed in Hawaii, further testing will be conducted in citrus orchards under California weather conditions. Through Dr. Joseph Morse of the University of California, Riverside, we will conduct weathering trials of the novel TMR dispensers in California (Riverside, Lindcove, Bakersfield, Ventura, and Costa Mesa, CA) beginning in July 2012. Climate data will be obtained from Hobo weather recorders maintained at each location. Weathered dispensers will be sent to Hawaii and Washington for bioassays and chemical analyses, respectively. Roger Vargas of US PBARC will oversee bioassays in Hawaii. Peter Cook of Farmatech and John Stark of Washington State University will collaborate on chemical analysis of wafers in North Bend, WA. Currently, approximately 30,000 sets of TML, ME, and C-L traps are maintained throughout the state. From a worker safety, convenience, and economic standpoint, Farma Tech TMR Mallet solid wafers with DDVP may be more cost effective, convenient, and safer to handle than current liquid lure and insecticide formulations (e.g. naled) used for detection programs for TML, ME and C-L responding flies in California. Cost/benefit analyses of Mallet TMR vs. standard trapping systems will be done.
Two 3-year field experiments are being conducted in two commercial orange blocks in Hendry County (southwest Florida). One of the groves is planted with ‘Earlygold’ oranges and the other with ‘Valencia’ oranges. Average HLB incidence estimated in both groves at the beginning of the experiment based on PCR analysis of a random sample of 160 trees was 98% in ‘Earlygold’ and 42% in ‘Valencia’. Experimental design is randomized complete block with 4 replicates and 4 treatments: (1) No insecticide, (2) Calendar applications, in order to drive vector populations close to 0, (3) nominal threshold of 0.2 psyllids per tap, and (4) nominal threshold of 0.7 psyllids per tap. Calendar applications are being applied every month. From March to June only treatment (2) received insecticide sprays because the nominal threshold was not detected in treatments (3) and (4). In March, treatment (2) was sprayed with spirotetramat (Movento MPC) at 16 fl oz/ac, in April Diflubenzuron (Micromite) at 6.25 oz per acre was used for the spray, in May treatment (2) was sprayed with abamectin (ABBA) at 15 fl oz per acre and in June the calendar applications treatment was sprayed with spinetoram (Delegate) at 4.5 oz. Horticultural mineral oil 2% was included with all the sprays. In addition, all treatments received a foliar nutritional spray according to a citrus greening remediation program widely used during the second major flushing period of the season (end of May). We are also evaluating effects of sprays on biological control, considering this to be a potential cost or benefit of the 4 treatment regimes tested. Exclusion techniques used to evaluate the role of predators on reducing ACP immature stages corroborated the importance of these natural enemies during the second flush period. In untreated plots receiving no sprays (Treatment 1) cohorts of ACP immature stages were reduced 74.8 ‘ 4.7% on branches covered by open sleeve cages compared to closed sleeve cages. The difference is assumed to be due to action of predaceous arthropods which have access only to psyllid nymphs in open cages. In contrast, ACP reduction in open cages was only of 19.3 ‘ 19.4% in the plots that received calendar sprays (Treatment 2, F = 10.44; d.f. = 1, 23; P < 0.01). This result would indicate a significant negative effect on naturally occurring biological control of this pest as a result of two years of monthly sprays using a rotation of selective and broad-spectrum insecticides. The influence of each ACP management strategy on the biological control of citrus leafminer immature stages was also evaluated during the same flushing period. Random samples of young expanded shoots were examined under the stereoscopic microscope to determine the proportion of mines in which development was completed. Mortality due to natural enemies was very high; less than 5% of the leafminers larvae reached the adult stage, with no differences among the 4 treatments of the threshold experiment on 'Earlygold'. Additional studies are also being conducted to assess how each ACP insecticide strategy is affecting to the natural occurring community of phytoseid mites, one of the most important groups of predators in agriculture. The results to date in the 'Earlygold' block are also showing how insecticides affect the abundance and diversity of these natural enemies. Treatment (1) showed a significant higher diversity (Shannon Index = 1.26 ' 0.08) than the rest of the treatments (0.67 ' 0.04, 0.79 ' 0.06 and 0.70 ' 0.07 for treatments (2), (3) and (4) respectively (F = 8.12; d.f. = 6, 15; P < 0.01). These results will be linked to differences in pest abundance and ultimately to crop yield and value.
Management of the Asian citrus psyllid (ACP) currently relies on the use of insecticides; however, aggressive use of insecticides to manage insect vector and greening disease has led to the development of resistance in ACP to various modes of action. Therefore, there is an urgent need to develop and evaluate alternative management programs for ACP and greening disease. The current project proposes to utilize citrus tristeza virus (CTV) engineered to express insecticidal peptides as a novel tool for ACP control. Previously, we have reported the success of two putative insecticidal peptides (A and B) in imparting deleterious effects on the growth and development of ACP. Plants containing peptides A and B have elicited reduced feeding, host selection, fecundity, and longevity of eggs and nymphs of ACP when compared to control plants. ACP surviving on plants containing peptides A and B also exhibited increased developmental time for egg and nymph when compared to control plants. Currently, we are evaluating effects of plants containing peptide C on the growth and development of ACP. We have started quantitative assays to determine the concentration of peptides expressed in samples from test plants are currently being developed. To evaluate possible antifeedant effects of peptide C, we have recently conducted feeding bioassays that measure honeydew production as a surrogate for ACP ingestion. Our preliminary data shows that feeding was significantly reduced on plants containing peptide C when compared to control plants (F=24.22; df: 1, 29; P<0.0001). Additionally, an experiment was conducted to compare the settling behavior of ACP on plants containing peptide C and control plants. Significantly more ACP adults were found on control plants at 48 h (F=9.54; df: 1, 14; P=0.0080) and 72 h (F=13.74; df: 1, 14; P=0.0023) when compared to plants containing peptide C. Future bioassays will be conducted to determine the effects of plants containing peptide C on the growth and development of ACP and another phloem-feeding citrus pest, the brown citrus aphid. In the upcoming months, we will complete experiments evaluating the efficacy of peptide C against the Asian citrus psyllid. Furthermore, we continue to await systemic infection of plants with another novel CTV-vectored peptide. Plants were tested recently for infection with the CTV construct using an enzyme linked immunosorbant (ELISA) assay; however, only two positive plants were found, likely due to the fact that plants were inoculated only one month prior to testing. In addition to evaluating the effect of CTV vectored peptides against ACP and the brown citrus aphid (reported previously), we have recently begun to evaluate the effect of three peptides against the ACP parasitoid Tamarixia radiata. Individuals from a recently-established colony of these insects are currently being evaluated in choice tests and fitness bioassays to determine the effect of peptides on paraitoid host selection and fecundity. Briefly, the effect of peptide plants on T. radiata host selection is evaluated by releasing insects into a T-tube olfactometer. Insects are able to choose between two odor fields located in the arms of the olfactometer. Each arm is connected to an odor source placed in a volatile collection chamber (psyllid-infested plants with CTV-peptide contructs, psyllid-infested plants without CTV constructs, and the respective non-psyllid control plants).
Ultra High Performance Liquid Chromatography – Pesticide Residue Analysis (June 2013 Update) Work continued to compare protocols for analysis of potential insecticide residues in citrus nectar. Early in this quarter, problems arose with the equipment resulting in the inability to obtain a clean baseline. Technical support from the equipment manufacturer was requested and 3 separate visits were made by technicians in attempt to resolve the issues which took nearly 2 months to solve. Multiple issues were identified and resolved one at a time including a bad electronic component that controlled the injector, pump issues requiring replacement, and a clogged rinseate line. Ultimately, issues with the equipment were resolved and method validation for nectar samples continued until low levels of contamination appeared corrupting the baseline. The source of contamination was ultimately identified and resolved. Sample analysis of field collected samples from 2013 began in late June.
Progress has been made on three primary objectives of the project: 1) Develop a generic epidemiological model that can be used to compare control scenarios and to optimize the probability of controlling and managing high-risk pathogens of agricultural significance. 2) Development and testing of efficient methods of statistical inference to estimate epidemiological parameters from maps of emerging epidemics. 3) Develop user friendly model ‘front ends’ that can be used by researchers and regulatory agencies Most work has been focused on this primary objective and in the underpinning statistical methods that are used to estimate parameters for emerging epidemics. The parameters are then used to inform model predictions of the likely further spread of disease and the effectiveness of different management and control strategies. We now have a set of robust and flexible epidemiological models to analyze and predict the spread of emerging pathogens across a range of scales extending from within-plantation to the landscape and regional scales. The models are being tested using extensively and intensively mapped data for citrus HLB and citrus canker provided. These form unique data sources comprising successive maps of diseased and susceptible hosts over time. The data are used to test the statistical methods for parameter estimation as well as the applicability and flexibility of the epidemiological models to particular host-pathogen systems. The data have the added advantage of enabling us to look, in the case of HLB, at how host age affects the transmission of disease and for canker and HLB at variability across different sites in disease transmission patterns and characteristics. The models are designed to be stochastic and biologically realistic but with relatively few epidemiological parameters to be estimated prior to use. The models are also developed as part of a flexible tool-box so that they can be readily adapted to new disease threats. To date we have completed the following in constructing the models: 1) Development of computationally fast epidemiological models to predict future spread of disease at a range of scales; 2) Coupling of the models with GIS to compute spread and model control over extensive areas and realistic agricultural landscapes and under realistic environmental conditions; 3) Adaptation of the models to incorporate a range of control strategies and to compare the effectiveness of different management and control strategies under uncertainty. The models also allow for incorporation of latent and cryptic periods and for dual sources of transmission, for example distinguishing between tree-to-tree spread within a grove and introductions from outside the area of interest. The MCMC methods have successfully been used to discriminate amongst alternative models (for example between models with different characteristics to describe dispersal, transmission, latent and cryptic periods) and to select the optimal model to describe the spread of HLB within plantations and citrus canker within urban environments. Publications: Cunniffe, N.J., R.O.J.H. Stutt, R.E .DeSimone, T. R. Gottwald, and C.A. Gilligan. 2012. Webidemics: Webbased Interactive Demonstration of Epidemiological Modelling Informing Control Strategies. To be submitted to PLoS One. Gilligan, C. A., F. M. Neri, A.R.. Cook, G. J. Gibson, and T. R. Gottwald. 2012. Bayesian analysis of an emerging epidemic: citrus canker in urban Miami. To be submitted to Journal of the Royal Society Interface.
Ultra High Performance Liquid Chromatography – Pesticide Residue Analysis (June 2012 Update) The purpose of this proposal was to purchase a LC-MS-MS in order to facilitate ongoing CRDF funded research requiring the analysis of pesticide residues in citrus leaf tissue. Funding provided by CRDF payed for a portion of this equipment which was cost-shared by UF-IFAS. Following the funding of this project, we placed an order and received the proposed equipment on June 18, 2012. The facility where the equipment will be housed is being prepared (gas, electric, etc…) so that installation can occur. The installers are scheduled to arrive and setup the equipment next month.
We are continuing to solicit sequences that can be used to prepare RNAi molecules that may silence ASP genes resulting in mortality. As these sequences are selected, we are feeding the resulting RNAi molecules to adult ASP using our feeding system. Results comparing mortality of the these RNAi molecules on psyllids will be reported later after the comparisons are complete.
The objective of this project was to investigate three questions: 1) How long does a leaf needs to be infected by Guignardia citricarpa before ascospore production can be initiated; 2) How does infection and colonization of leaves by Guignardia citricarpa occur and potentially showing how pseudothecia, the sexual spore producing structures, are produced; and 3) what is the interaction between the common twig colonizing pathogen Diaporthe citri and the black spot pathogen Guignardia citricarpa and whether they can co-exist to successfully sporulate on dead twigs. The graduate student, Nan-Yi Wang, whose Ph.D. project this is, continues his studies in Gainesville this term and is making good progress in his classes. He is also conducting research while in Gainesville. We have redesigned the mating gene primers several times but have not found any products with homology to known mating genes. We are evaluating new strategies to approach this program. He has finally had success transforming G. citricarpa with GFP. He found that the fungus is very sensitive to hygromycin, a selectable marker, but was eventually able to transform protoplasts with modifications to his protocol. The isolates are being evaluated to make sure that the growth and other characteristics other than the GFP are similar or the same as wild type The trees have been purchased for the greenhouse experiments but the air conditioner broke down so needed to wait for delivery until the air conditioner in the quarantine house had been repaired.
This is a three-year research project that started in June, 2012. The overall goal of this research is to efficiently deliver antimicrobial molecules into citrus phloem against the HLB bacterium. The quarterly (July~Sep) research focused on designing the W/O (water in oil) and O/W (oil in water) nanoemulsions by evaluating the ideal adjuvant mixtures of solvents (ethanol, acetone, methyl acetate, and ethyl acetate), oils (soy oil, cremorohor, carvacrol, p-cymemen, orchex796) and lipophilic (span80, span85) and hydrophilic surfactants (tween20, tween80). The nanoemulsions were first evaluated for transparency, viscosity, and other physical properties that would make them good candidates for moving molecules into citrus phloem . This evaluation indicated that several O/W nanoemulsion formulations and several W/O nanoemulsion formulations had the desired properties. In addition, seven compounds from the Citrus Research and Education Center, IFAS, UF and one compound, epsilon-L-polyline, from China were tested for their effectiveness against HLB bacterium by our grafted-based chemotherapy method (Zhang et al., 2012). Three effective compounds from the Contest were treated by nano-green (one of the commercial nano-products) and applied to HLB-affected citrus by foliar-spray in the greenhouse. The results will be reported in the future.
The overall objective of this one year project was to rapidly screen and evaluate chemical compounds against citrus HLB using a graft-based screening method (Zhang et al., 2012). A total of 59 chemical compounds were tested based on the ranking of an expert panel and the mode of action of the compounds. HLB-affected lemon scions were soaked in the above solutions overnight in a fume hood and grafted into two-year-old healthy grapefruit rootstocks. First samples for DNA extraction were taken 4 months after inoculation; subsequent samplings were taken at 2 month intervals. Four types of data were collected: Las titer in scions and rootstock based on qPCR Ct values, transmission of the bacteria from the scion to the grapefruit rootstock, survival of the infected/grafted scion and growth of new leaves from the scion. The 59 compounds were placed into four groups based on the above data. (1) Highly effective (Group O): Eight out of 59 compounds were clustered in this group, including Ampicillin, Actidione, Carbenicillin, and Nicotine. All the molecules in this group reduced Las titers to undectable levels (Ct values of more than 38.0) in the inoculated plants (grafted scions and rootstocks). All molecules in this group were antibiotics except Nicotine. (2) Effective (Group I): Twenty-five out of 59 compounds were clustered in this group, including Validoxylamine A, Hygromycin B, Poly-l-arginine, Carvacrol and Gossypol. Some of these compounds, such as Carvacrol, Validoxylamine A and Gossypol were not medical-antibiotics. The effectiveness of group I molecules against HLB bacterium was less than those in Group O, but they could greatly suppress the HLB bacterium with average Ct values of 33.8 and detectable Las in less than 40% of the scions . (3) Partly effective (Group II): Sixteen out of 59 compounds were clustered in this group, including Thujone, Hydroxyurea crystalline, Polymixin B and Neomycin. Compared to the water control, they could partly suppress the HLB bacterium with Ct values of 28.6, and 74.7% scion infection. (4) Non-effective (Group III): Ten out of 59 compounds were classified into this group, including Meso-erythritol, Lincomycin, 2-methyl-4-isothiazolin-3-one and Zlineb. Similar to the water control (CK1 and CK2), the compounds in this group were not effective in suppressing the HLB bacterium with average Ct values of 26.8 and 72.6% scion infection. Three of the 59 compounds were found to be highly phytotoxic to citrus, especially Actidione, Oxytetracycline and M-cresol. The other 56 compounds were not phytotoxic due to more than 80% of scion survival and 40% of scion grown. Based on the this research, two manuscripts will be prepared for publication. The compounds in Group I and Group O may be useful for field control of HLB pending field testing, improved application methods and registration.
This is a three-year research project that started in June 1, 2012. The overall goal of this research is to efficiently deliver antimicrobial molecules into citrus phloem against the HLB bacterium. The objectives focused on will be : 1) Designing nanoemulsions by evaluating the ideal adjuvant mixtures of solvents, oils, lipophilic and hydrophilic surfactants based on the physicochemical characterization of the compounds; 2) Evaluating penetrants to promote uptake, translocation and diffusion of molecules into phloem based on leaf and bark surface characteristics; 3) Developing an efficient transdermal/translaminar delivery process and ideal formulations of compounds for foliar-spray or basal bark applications. Recent studies from Contest (CRDF#400) indicated that some non-medical antibiotics were effective in eliminating or suppressing the HLB bacterium using the graft-based screening method (Zhang et al., 2012). The major limitation to applying these compounds in the field will be to rapidly and efficiently deliver these compounds to the citrus phloem where the HLB bacterium resides. We therefore propose to screen and assess the components of nanoemulsions to improve the efficiency of delivery of the compounds into citrus in the first quarter research of this project. The overall experimental plan has been developed. The physicochemical characteristics of these effective compounds were evaluated and tested, such as solubility. The chemicals were purchased and nanoemulsions were prepared with water in oil (W/O) for lipophilic compounds and oil in water (O/W) for hydrophilic compounds. The HLB affected citrus to be used for this research was identified in the greenhouse and in the field. Some effective compounds combined with one kind of commercial nanoemulsion product (Nano-green) were used to treat HLB-affected citrus by foliar-spray and soil soaking in the greenhouse in June 2012. One OPS student will be hired and will be available in August, 2012.
Having shown that oral uptake of ~300 bp dsRNA fragments matching the coding region to either psyllid Vacuolar ATPase or cathepsin can induce mortality in the Asian citrus psyllid, comparisons were made to determine the optimal dsRNA size. Psyllids were fed either the ~300 bp dsRNAs directly or after processing to siRNAs with the Dicer enzyme. Results showed that the 300 bp dsRNAs induced greater mortality and that observed with processed siRNAs. Furthermore, non-linear dose dependent toxicity of the ~300 bp dsRNAs suggesting complex interactions that have not yet been characterized with respect to dsRNA induced toxicity in insects.
The project was initiated during this quarter. Initiation involved Hiring of personnel and adaptation of facilities to support project operations including increasing plant production to support psyllid colonies and increasing psyllid rearing. Experimental protocols were also optimized for large scale screening to be conducted during this time. Meetings were held with Innocentive review panel to chose the dsRNAs that will be used in the screening process. Initial testing of dsRNAs were performed and are now being replicated with 3 dsRNA targets.
(863) 956-8817
(863) 956-5894
700 Experiment Station Road
Lake Alfred, FL 33850
Email Us
Notifications