interna’onal*research* conferenceon* huanglongbing
TRANSCRIPT
Interna'onal Research Conference on Huanglongbing
Important Points and Take
Home Messages
Entomology Presenta'ons
Today’s Summaries
• Psyllid biology / ecology / HLB pathogen transmission
• Insec=cide-‐based management of ACP / HLB
• Molecular-‐based approaches to ACP management
Poster 5.11 The stripped mealybug, Ferrisia virgata, a new vector of the Huanglongbin bacterium “Candidatus Liberibacter asia=cus.” Pi=no, M., Hoffman, M.T., Zhou, L., Duan, Y.P. and D. Hall
• Found to readily acquire the HLB pathogen • Not as likely to inoculate a plant with the pathogen compared to psyllids (reduced inocula=on success rate)
• Pest with limited dispersal…minimal spread capabili=es • Possible headache for fresh fruit movement
Poster 2.11 Occurrence of Diaphorina citri in an unexpected ecosystem: the Lake Kissimmee State Park forest. Mar=ni, X., Addison, T., Fleming, B., Jackson, I., Pelz-‐Stelinski, K., and L.L. Stelinski
• Yellow s=cky traps used to survey for psyllids in Kissimmee forest (Jul – Oct 2012).
• Closest citrus grove 2.3 km • Low levels of psyllids trapped, but shows they are present • No psyllids observed on wild plants in the swamp • Laboratory no-‐choice tests with 3 most abundant plant species found in
swamp • Gallberry, Blueberry and Red Bay • All unsuitable for adult psyllid long-‐term survival (dead acer 3 days) • No reproduc=on found on these hosts
• While no wild hosts iden=fied in this study, provides indirect evidence that psyllids could be moving from swamps into adjacent citrus groves
Talk 5.2. Induced release of a plant-defense volatile ‘deceptively’ attracts insect vector to plant infected with a bacterial pathogen. Stelinski, L.L., Mann, R.S., Ali, J.G., Hermann, S.L., Tiwari, S., Pelz-Stelinski, K.S., and H.T. Alborn.
• Citrus trees produce methyl salicylate in response to HLB infec=on as well as psyllid feeding
• Methyl salicylate has been iden=fied as an agractant for both pests and beneficials in a number of crops
• In citrus, it serves to agract psyllids to HLB infected trees (to pick up Las) • Psyllids are preferen=ally agracted to newly HLB-‐infected trees • As trees decline (old infec=on), agrac=on of psyllids to HLB infected trees decreases
• Increased nutri'onal sprays to ‘old infec'on’ trees increases their aErac'veness to psyllids
Talk 7.4. Vector control and foliar nutri=on for management of huanglongbing in Florida citrus. Stansly, P.A., Arevalo, H.A., Qureshi, J.A., Jones, M.M., Hendricks, K., Roberts, P.D., and F.M. Roka.
• Experiment was conducted that included the following treatments: 1) Control, 2) Insec=cide for psyllids, 3) nutri=onal sprays, and 4) Insec=cide for psyllids + nutri=onal sprays.
• No treatments reduced HLB infec=on rate…increased to ~95% • Ct values were higher in insec=cide treated plots sugges=ng reduced disease severity
• Yields higher in vector control plots in yrs 2-‐4 • Increased yields in nutri=on plot in yr 4 only • Combined insec=cide + nutri=on treatment was best in all 4 yrs
Talk 5.7 Low acquisi=on rates of ‘Ca. Liberibacter asia=cus’ by Diaphorina citri Kuwayama from citrus plants exposed to high temperatures Lopes, S.A., Luiz, F., Mar=ns, E.C., Fassini, C.G., Sousa, M.C., Barbosa, J.C., Beape, G.A.C.
• Observa=ons in Brazil suggested that HLB spread was more slow to occur in the warmer areas of the country
• Examined the effects of temperature on the ability of psyllids to acquire the Las bacterium from new leaf growth
• Found when temperatures were higher (up to 100F) the levels of Las dropped in the new leaf =ssues
• Acquisi=on of Las by psyllids also decreased • This effect declined the longer a tree was infected with the HLB pathogen
• The longer HLB infected trees stay in the field, the less likely bacterial popula=ons will fluctuate at different =mes of the year, thus the plants will be more likely to serve as a year-‐round source of inoculum for psyllids to acquire the pathogen.
Poster 5.9 Seasonal shics in Candidatus Liberibacter asia=cus prevalence in the vector Diaphorina citri in Florida. Ebert, T.A., Brlansky, R.H. and M.E. Rogers
• (2008-‐2012) survey of the incidence of psyllids carrying the HLB pathogen (pcr analysis of ~70,000 ACP)
• Are there =mes of the year psyllid control is more important to reduce HLB spread?
• Years 1-‐2 : more pronounced seasonal effects, par=cularly in the cooler fall and winter months (Sept-‐Feb) – Also =me when more flush was present for nymphal acquisi=on
• Years 2-‐3: seasonal effects on psyllids carrying the pathogen were less pronounced. – In loca=ons with a high incidence of HLB infected trees, incidence
of psyllids carrying pathogen was high (>60%) year-‐round
Poster 5.9 Seasonal shics in Candidatus Liberibacter asia=cus prevalence in the vector Diaphorina citri in Florida. Ebert, T.A., Brlansky, R.H. and M.E. Rogers
• In loca=ons with lower tree infec=on rates (and beEer psyllid control) incidence of psyllids carrying the HLB pathogen was significantly lower (<5% on average)
• Overall, the results show that as the rate of HLB infected trees increases over 'me, so does the incidence of psyllids carrying the pathogen, thus the need for year-‐round control of ACP.
Poster 1.7 Incidence of Huanglongbing in commercial orchards in northwest Parana, Brazil Mula=, F., Nocchi, P.T.R., Zanugo, C.A., Belasque, J.,Nunes, W.M.C.
• Examined the =ming of insec=cide sprays on different varie=es and the effect on HLB infec=on rate
• (Once infected trees were detected they were removed) • Applica=ons =med to the presence of psyllids (scou=ng)
• 0.1 – 0.4% HLB infected trees • Applica=ons made only when new flush present
• 2-‐10% HLB • Calendar-‐based applica=ons (every 20 days)
• 0.04-‐0.12% HLB • Results showed that HLB infec=on rates remained lowest using the preven=ve calendar-‐based sprays (every 20 days)
Poster 6.16 Thresholds for HLB vector control in infected commercial citrus and compa=bility with biological control Monzo, C. Hendricks, K., Roberts, P. and P.A. Stansly
• Calendar-‐based monthly sprays provided best control of psyllids popula=ons
• No difference in psyllid popula=ons where no insec=cide used compared to using a threshold of 0.2 or 0.7 psyllids
• Conducted a ‘preliminary’ economic analysis which suggested that while yields were higher in the calendar spray treatments, the costs of their insec=cide treatments ($555.82/A) did not jus=fy the yield increase
• They also emphasized the fact that the calendar spray program had hidden costs in terms of killing beneficials
• 1% oil sprays were evaluated for psyllid control • There was an ini=al 70% reduc=on in psyllid coloniza=on of oil
treated plants. • The authors suggest that oil has a repellent effect on Asian citrus
psyllid. • However, psyllids colonize new flush acer treatment (dries), which
reduces effec=veness of mineral oil treatments. • Coverage using mineral oil is paramount for it to be effec=ve. • Immediately following treatment, an 82% reduc=on of egg laying
was observed on oil treated plants • Both rain and development of new flush reduced effec=veness. • 1% mineral oil treatment acts as a psyllid repellent and causes up
to 8% mortality of adults.
Talk 6.8 Effect of mineral oil on host selec=on and control of Diaphorina citri on citrus. Miranda, M.P., Micelli, M/L/, Felippe, M.R., Caldeira, R.E., and Yamamoto, P.T.
Poster 6.20 Frequent low volume sprays of Hor=cultural Mineral oil (HMO) for psyllid and leafminer control Jones, M.M., and P.A. Stansly
• Field trials comparing the efficacy of low volume oil sprays versus conven=onal insec=cide sprays
• Conven=onal insec=cide sprays performed beger in terms of reducing overall psyllid popula=ons throughout most of the year
• Most pronounced when psyllid popula=ons were at their highest levels
• LV oils sprays did provide some suppression of psyllids, par=cularly the nymphal stage
• There was no difference between any of the treatments in terms of juice quality
Poster 6.24 Introducing DuPont Exirel and Verimark new insect control products for pest management and op=mizing yields in Florida citrus Por=llo, H.E., Royal, S.S., Taylor, J.E., Temple, J.H., Truszkowski, A.T., Mares, J.T., Cameron, R.A., Anan, I.B. and J.M. Alvarez.
• Cyazypyr is a new mode of ac=on that provides excellent control of both leafminer and psyllid
• Field trial results show dura=on of control equal to if not beger than most commercial standards
• Presented EPG-‐based feeding data showing phloem feeding reduced but not prevented, psyllids s=ll spent 14% of =me in phloem on cyazypyr treated plants
• Pathogen transmission can happen at any =me during phloem feeding, there is no =me requirement once the phloem is reached
• Two-‐year field trial using primarily soil applica=ons of cyazypyr on young trees reduced HLB infec=on rate from 71% (untreated) to 25-‐31% in cyazypyr treatments.
• While this product is not going to directly prevent pathogen transmission from occurring, this will be a valuable new tool for controlling both psyllid and leafminer and helping to prevent insec=cide resistance.
RNAi approach to psyllid control
• Citrus psyllid genome project provides new approaches to psyllid control
• Once you know what a certain gene does, you can shut off that gene using dsRNA
Poster 6.27 Targe=ng juvenile hormone metabolic genes in the Asian citrus psyllid as a strategy to reduce the spread of citrus greening disease Van Ekert, E., Borovsky, D., Powell, C.A., Cave, R.D., Alessandro, R.T. and R.G. Shagers
• Iden=fica=on of gene regula=ng juvenile hormone • Juvenile hormone regulates nymphal growth and development • Key in the mol=ng process (one nymphal stage to the next)
• Could now target this gene to prevent nymphal development
• Using potato psyllid as a model to look for genes to target in ACP
• Important found genes include Hemolysin A, HLyE, pore forming toxin, biofilm forma=on. These genes may implicated in Las circula=on and propaga=on within ACP
Talk 5.6 Transla=ng Anatomical Structures and Func=onal Genomics of Candidatus Liberibacter asia=cus and solanacearum Into Circula=ve, Propaga=ve Vector-‐Mediated Transmission Processes Tonja Fisher, J. Cicero, M. Vyas, R. He, W. Nelson, M. Willer, C. Soderlund, D. Gang, and J.K. Brown
Talk 4.2 Sequencing and annota=on of the Wolbachia endosymbiont of Diaphorina citri by the CGHLB Genome Resources group reveals candidate sources of interac=on with the insect host Surya Saha, Wayne Hunter, and Magdalen Lindeberg
• Generated and annotated drac genome of the Wolbachia endosymbiont of ACP
• Annoted genes include: – 54 predicted ankyrin proteins (may play a role in host reproduc=ve manipula=on)
– Type IV secre=on system (linked export of ankyrins, which regulate host gene expression)
– bacterioferri=n (linked to host iron homeostasis)
Poster 6.13 Genera=ng Asian citrus psyllids with twis=ng wings to prevent the spread of greening disease El-‐Shesheny, I., Harjeri, S. Gowda, S. and N. Killiny
• Topical applica=on of dsRNA to psyllid nymphs targe=ng wing forming gene
• Using the ctv vector approach, created plants expressing this par=cular dsRNA
• Wing gene may not be suitable for use in transgenic citrus because it may affect other insects (including beneficials)
• Have iden=fied 11 unique psyllid genes ready for screening • Currently not CRDF funded, so unclear how quickly this will move forward
Talk 5.3 Disrupt the bacterial growth in the insect vector to block the transmission of Candidatus Liberibacter Asia=cus to citrus, the causal agent of citrus greening disease Killiny, Nabil, Hajeri, S., Gowda, S., and Davis, M. J.
• Biofilm forma=on required for HLB pathogen transmission
• Acyl-‐Homoserine lactones (AHLs) produced by a psyllid endosymbiont play key role in binding of Las bacteria (biofilm forma=on)
• LuxR protein can bind to AHL preven=ng Las bacteria from agaching and forming biofilm
• Can introduc=on of extra LuxR protein disrupt biofilm forma=on causing psyllids to be unable to transmit bacteria?
• Developed plants which produce LuxR protein • Bind to available AHLs inside insect responsible for biofilm forma=on
• Psyllids which feed on these plants lost the ability to transmit
the HLB pathogen (biofilm detachment and dispersal)
Talk 5.3 Disrupt the bacterial growth in the insect vector to block the transmission of Candidatus Liberibacter Asia=cus to citrus, the causal agent of citrus greening disease Killiny, Nabil, Hajeri, S., Gowda, S., and Davis, M. J.
• Proof of Concept -‐ Targe=ng AHLs with LuxR proteins can prevent pathogen transmission by psyllids
• Posi=ve Agributes: safe for humans, only targets endosymbiont systems within the psyllid
• Transgenic plant lines will be produced, that will also target other systems within the plant preven=ng pathogen acquisi=on from plants as well.
Talk 5.3 Disrupt the bacterial growth in the insect vector to block the transmission of Candidatus Liberibacter Asia=cus to citrus, the causal agent of citrus greening disease Killiny, Nabil, Hajeri, S., Gowda, S., and Davis, M. J.