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UF/IFAS Citrus Research and Education Center

UF/IFAS Citrus Research and Education Center


Insect transmission of Plant Bacterial Pathogens | PLP 6905
3 Credits

The insect transmission process includes two main steps, both taking place during vector feeding on plants. The first step consists of pathogen acquisition by the vector from the source plant (host); the second step is the inoculation from the vector into a recipient plant.  However, in order to successfully accomplish the pathogen transmission, many interactions between the host, pathogen, and vector at the biochemical and molecular levels are involved. 

The bacterium-insect vector interactions involve propagation, circulation, and persistance with the vector body. The growth of plant-pathogenic bacteria in the vector's hemolympth indicates that the hemolymph contains all the necessary nutrients for bacterial growth. Thus, insect-transmitted plant-pathogenic bacteria may alter their vectors' fitness, survival, behavior, and metabolism.  In addition to nutrients, bacteria can take up energetic nucleotides, such as ATP, from its vector.  Interestingly, some bacteria are not circulative within the vector body, but localize only in the foregut where they multiply and form biofilm.

The interactions between the pathogenic bacteria and their host plant are limiting factor for insect transmission. Vector-plant interactions including attraction, preference, host specificity, and feeding site are also important factors relevent to transmission. The availability of bacterial cells to the vector in the host tissues is essential for the acquisition step.  In addition, in certain cases, the bacteria possess different transcriptomic types in plant and only one type is transmissible.  In brief, tritropic interactions should be well established in order to achieve successful transmission.

The course will discuss all aspects of insect transmission of plant pathogenic bacteria and will include several study cases.  Students will actively participate in lectures by reading and evaluating publications prior to the lectures.  There will be two lectures per week -- a two-hour lecture about a main topic and a one-hour lecture for discussion or guest lecture.  Guest lectures will be given by renowned professors and researchers in vector-borne plant bacterial disease.  Some guest lectures will be in prerecorded video format.  One research paper on a vector-borne bacterial disease (of student's choice) will be required for course completion.

  • Snapshot

    Learning Objectives

    The overall goal of this course is for students to gain knowledge about both the endemic as well as exotic vector-borne plant bacterial diseases and the biochemical and molecular interactions among bacteria, plant host and insect vector.  By the end of this course, student should be able to: 

    - Understand the different transmission modes of plant bacterial pathogens 
    - Understand the biochemical and molecular interactions mediating pathogen transmission
    - Identify the role of insect vector biology and behavioral ecology in the spread of vector-borne disease
    - Identify the role of vector-plant interactions in transmission efficiency.
    - Become familiar with the potential control strategies to disrupt the insect transmission
    - Realize the role of bacterial adhesion proteins and exopolysaccharides in biofilm formation on the insect gut.


    There is no recommended text, however, students will need to have access to the Plant Pathology 5th ed. (2005) by G.N. Agrios, Elsevier Academic Press, Inc.  The book is available at CREC in the library and in the Department of Plant Pathology library

    Learning Modules

    The course content for this class is divided into 4 learning modules including 

    I.   Characterization of insect transmission of plant pathogenic bacteria
    II.  Bacteria-vector interactions at the molecular and biochemical levels
    III. Insects as host for plant bacterial pathogens: specificity (receptors) and energy and nutrition requirements 
    IV. Interfering with insect transmission

    Each module includes few lectures.  Every module has an associated graded quiz right after completion of the module.

  • Course Specifics


    Wednesdays @ 10:55-11:35 a.m. and Fridays @ 1:55-4:00 p.m.


    Building 7103, Room 5, Citrus Research and Education Center

    Phone: 863.956.8833 

    Office Hours: Wednesdays 10:00 am - 12:00 pm, or by appointment.


    Dr. Nabil Killiny


    Grading is based on the performance on two written exams; one midterm in-class plus one cumulative final exam.  In addition to two quizzes, term paper and participation in the discussion sessions.  Grades will be based on the following assessments:  



    Quiz 1


    Quiz 2


    Quiz 3


    Quiz 4


    Mid-term exam


    Discussion Sessions


    Term paper


    Final Exam (Comprehensive)




    Exams and Quizzes: There will be two lecture exams (mid-term and final).  Mid-term exam is not comprehensive (200 points).  The final exam is comprehensive (300 points) and scheduled for May 3, in Fifield building in Gainesville and the centers' libraries.  Additionally there will be four quizzes (25 points each) covering the four modules.

    Term Paper: Every student will need to write a term paper about a vector-borne disease of his/her choice.  Term paper should discuss the disease description, pathogen life cycle, vector life cycle, transmission mode, and pathogen-vector interactions.  100 points are assigned for the term-paper.

    Discussion Sessions: Discussion sessions are scheduled during the second lecture per week.  100 points will be assigned to the discussion activity.  50 points for peer review and presenting a research paper and 50 points for participation in discussions.

    Grade Scale: Final grades will be designated according to the following grade scale. This course uses the grade book function in Canvas for records-keeping and grade calculation; grades will be calculated on a percentage basis, but total course points associated with each percentage are given here for your convenience. For information on current UF policies for assigning grade points, see:

    Letter Grade




    92.00 - 100



    90.00 - 91.99



    88.00 - 89.99



    82.00 - 87.99



    80.00 - 81.99



    78.00 - 79.99



    72.00 - 77.99



    70.00 - 71.99



    68.00 - 69.99



    62.00 - 67.99



    60.00 - 61.99



    00.00 - 59.99


  • Course Policies

    Attendance and Participation

    Participation is a vital part of both the course experience since the students have the opportunity of hearing and asking questions of the many faculty that participate in this team-taught course.  Students will be expected to arrive at each class on time and prepared to fully participate in the lectures and the field trip.  If a student must miss a class due to illness or orther extenuating circumstances, he/she must listen to the missed lecture(s) that are posted.  Students are expected to come prepared to participate in the class lectures.  Students enrolled in the class should already have a basic understanding of the concepts of plant pathology.  Questions are highly encouraged.


    Students will participate in article discussions, held within the laboratory period, and will submit a brief "3-2-1" paper in advance of each discussion (see below).  Briefs and discussion participation will be graded through a combination of peer review and instructor review.

    Academic Integrity

    Standards will be upheld vigilantly at all times in this class.  Upon registering at the University of Florida, you signed the following statement: "I understand that the University of Florida expects its students to be honest in all their academic work. I agree to adhere to this commitment to academic honesty and understand that my failure to comply with this commitment may result in disciplinary action up to and including explusion from the University." On all work submitted for credit by students at the University of Florida, the following pledge is eithe required or implied: "On my honor, I have neither given nor received unauthorized aid in doing this assignment." You will be expected to keep these commitments in every aspect of your participation in this class.

    For more information regarding the Student Honor Code, please see:

    UF Distance Education Student Complaints

    Should you have any complaints with your experience in this course, which you are unable to resolve directly with the instructor, please visit to submit a complaint.

    UF Counseling Services

    Provides resources on campus for students having difficulties which may interfere with their academic performance.  Programs are available for general therapy, stress management, anger management, math confidence, career counseling, LGBT support, and many other specific needs.  Resources available to you include: 1) University Counseling Center, 301 Peabody Hall, 392-1575; 2) Student Mental Health Center, 392-1171; 3) Sexual Assault Recovery Services (SARS), Student Health Care Center, 392-1161; 4) Career Resource Center, Reitz Union, 392-1601.


    are available for students with disabilities.  Students requesting accommodations must first register with the Dean of Students Office (through Students with Disabilities Office, Peabody 202, 392-1261).  The Dean of Students Office will provide documentation to the student.  This documentation must be presented to the instructor when requesting accomodation.  For further information, see the Disability Resource Center (

    Software Use and Copyright

    All faculty, staff, and students of the University are required and expected to obey the laws and legal agreements governing software use.  Failure to do so can lead to monetary damages and/or criminal penalties for the individual violator.  Because such violations are also against university policies and rules, disciplinary action will be taken as appropriate.