Team:NYMU-Taipei/Project-Model

Epidemic

B. dorsalis is a major cause of annual agricultural losses due to oviposition in fruits. We hereby introduce our prototype trap and M. anisopliae, our genetically engineered fungi, to address this issue.
Our model aims to demonstrate that combining our prototype with the fungi can reduce the population of B. dorsalis. We selected and revised the SEIR model, which fits the ideal assumption in epidemiology, to make it more practical for our purpose.

Symbol

Description

Susceptible

B. dorsalis is slightly or moderately resistant to M. anisopliae

Exposed

B. dorsalis is exposed to a low amount of M. anisopliae in our trap; disease will be spread further during mating.

Infected

M. anisopliae enters B. dorsalis’ hemolymph and initiates cell division.

Death

B. dorsalis dies from the infection of M. anisopliae.

Based on our assumptions, we developed a set of differential equations that characterizes the nature of the epidemic in our model:

  • dms/dt=daily_move_in-trap-death_rate*ms

  • dfs/dt=daily_move_in-death_rate*fs


    • Parameter


    Type

    Name

    Meaning (Value)

    Reference

    Constant

    Mating　rate

    0.8635

     

    daily_capture

    40

     

    daily_move_in

    0

     

    K

    adult death rate (0.05)

    [1]

    k0

    larval death rate (0.23)

    [2]

    Variable

    ms

    susceptible male

     

    Fs

    susceptible female

    me

    exposed male

    Fe

    exposed female

    mi

    infected male

    Fi

    infected female

    D

    Death

    Result


    The graph above shows the initial increase in population due to the attraction of B. dorsalis from the surrounding environment. However, the population subsequently drops when the M. anisopliae infection begin to spread. The results indicate that the use of prototype combined with the fungi yields a 70% decrease in the B. dorsalis population. Thus, we deduce that our product can be deployed in orchards and farms a few weeks prior to harvest to minimize crop damage.





    Reference

    1. Life History and Demographic Parameters of Three Laboratory-reared Tephritids (Diptera: Tephritidae) R. Vargas - D. Miyashita - T. Nishida - Annals of the Entomological Society of America - 1984

    2. Effect of Temperature on the Development and Survival of Immature Stages of the Carambola Fruit Fly,Bactrocera carambolae, and the Asian Papaya Fruit Fly,Bactrocera papayae, Reared On Guava Diet Solomon Danjuma - Narit Thaochan - Surakrai Permkam - Chutamas Satasook - Journal of Insect Science - 2014