Accesso libero

An Agent-Based Metapopulation Model Simulating Virus-Based Biocontrol of Heterodera Glycines

Safyre Anderson
Safyre Anderson
, 
Chinmay Soman
Chinmay Soman
, 
Sadia Bekal
Sadia Bekal
, 
Leslie Domier
Leslie Domier
, 
Kris Lambert
Kris Lambert
 e 
Kaustubh Bhalerao
Kaustubh Bhalerao
   | 03 giu 2018
Journal of Nematology's Cover Image
INFORMAZIONI SU QUESTO ARTICOLO
Articolo precedente
Articolo Successivo
Cita
Pubblicato online: 03 giu 2018
Pagine: 79 - 90
DOI: https://doi.org/10.21307/jofnem-2018-002
Parole chiave
© 2018 Safyre Anderson et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1:

The Soybean Cyst Nematode Simulation (SCNSim) framework. Envi-ronment, Nematode, Viral Infection and Soybean boxes represent classes in an object-oriented framework, with their respective properties listed within the boxes, and interactions between each other shown by solid arrows. The Nematode class is a simplified model of the life cycle of the nematode Heterodera glycines. SCNSim stochastically simulates a population of nematode agents governed by a dynamic environment, health of the host soybean crops, and the nature of the viral infec- tion. Nematode transition between life stages. Stages J2-J4 feed on the soybean plant diminishing the plant health. The environment modulates the growth of the soybean plant as well as the hatching and transition to the cyst stage in the nematode. The viral parameters are a property of the nematode objects that reduce their health. Viruses transmit horizontally and vertically. Nematodes are removed from simulation when their Health parameter drops below zero.
The Soybean Cyst Nematode Simulation (SCNSim) framework. Envi-ronment, Nematode, Viral Infection and Soybean boxes represent classes in an object-oriented framework, with their respective properties listed within the boxes, and interactions between each other shown by solid arrows. The Nematode class is a simplified model of the life cycle of the nematode Heterodera glycines. SCNSim stochastically simulates a population of nematode agents governed by a dynamic environment, health of the host soybean crops, and the nature of the viral infec- tion. Nematode transition between life stages. Stages J2-J4 feed on the soybean plant diminishing the plant health. The environment modulates the growth of the soybean plant as well as the hatching and transition to the cyst stage in the nematode. The viral parameters are a property of the nematode objects that reduce their health. Viruses transmit horizontally and vertically. Nematodes are removed from simulation when their Health parameter drops below zero.

Figure 2:

Soybean cyst nematode mortality across viral pathotypes. Each panel describes the mortality in the nematode population as a function of the mutation rate for a given initial virulence V0. Greater prevalence of the infection resulted in higher mortalities than the low release treatments.
Soybean cyst nematode mortality across viral pathotypes. Each panel describes the mortality in the nematode population as a function of the mutation rate for a given initial virulence V0. Greater prevalence of the infection resulted in higher mortalities than the low release treatments.

Figure 3:

SCN suppression over time at mutation rate of 0.4 across initial virulence V 0: (A) virus mortality rate changes over time; (B) virus prevalence changes over time; and (C) virus transmission rate changes over time for different virus initial virulence (V 0) rate.
SCN suppression over time at mutation rate of 0.4 across initial virulence V 0: (A) virus mortality rate changes over time; (B) virus prevalence changes over time; and (C) virus transmission rate changes over time for different virus initial virulence (V 0) rate.

Figure 4:

Replication ratio (R v) with respect to mutation rate of viruses with respect to mutation rate at five different initial virulence rate (V 0) over 4 crop years. Median R v values are accompanied by smoothing (loess) curves with 95% confidence bands.
Replication ratio (R v) with respect to mutation rate of viruses with respect to mutation rate at five different initial virulence rate (V 0) over 4 crop years. Median R v values are accompanied by smoothing (loess) curves with 95% confidence bands.

Figure 5:

Four-dimensional scatter plot showing virus-caused nematode mortali- ties over time across treatments by mutation rates and virulences. Each panel in the grid layout denotes the evolution of transmissibility b and virulence v over time for a specific mutation rate and initial virulence.
Four-dimensional scatter plot showing virus-caused nematode mortali- ties over time across treatments by mutation rates and virulences. Each panel in the grid layout denotes the evolution of transmissibility b and virulence v over time for a specific mutation rate and initial virulence.

Figure 6:

Relationship between transmissibility and virulence across three distinct initial virulence values (V 0 = 1.5, 2.0, and 2), with a single mutation rate, m = 0.4 over 4 years. Mortality rate of soybean cyst nematodes are shown in different colors.
Relationship between transmissibility and virulence across three distinct initial virulence values (V 0 = 1.5, 2.0, and 2), with a single mutation rate, m = 0.4 over 4 years. Mortality rate of soybean cyst nematodes are shown in different colors.

Numerical properties of the viruses in the Soybean Cyst Nematode Simulation Framework SCNSim.

Definition
Property Symbol Range in vivo in silico
Viral Load L 0 1 Amount of viral particles per host Scalar multiplier to nematode health decrement
Virulence V 0, v R > 0 Pathogen damage inflicted on host Multiplier to Viral Load
Transmissibility b 0, b 0 1 Rate of infection of suscep-tible population Proportion of viral load sexu-ally transmitted from infected male to a recipient female or from female to egg
Prevalence i 0, i 0 1 Disease prevalence in a population Fraction of initial population infected
Durability D 0 1 Longevity of virus parti-cles. The complement is an ampli-fying constant on increasing viral load.
Mutation Rate M 0 1 Proportion of progeny gen-eration with significant ge-netic variation Probability of virus proper-ties undergoing mutation

Environmental set points and nematode stages modeled in the Soybean Cyst Nematode Simulation Framework (SCNSim) based on figures in Schmitt et al. (2004).

Model compartment Parameter description Value
SCN life cycle laws SCN eggs per cyst 300-500a
Minimum hatching temperature 16° C
Maximum hatching temperature 36° C
Cyst dormancy initialize temperature < 20° C
Probability of hatching from egg sac 0.2b
Probability of hatching from cyst 0.002b
SCN life stages Egg state 1-5 d
J1 state 1-2 d
Unhatched J2 1-3000 d
Hatched J2 1-4 d
J3 3-4 d
J4 male 5-6 d
J4 female 3-4 d
Adult male 1-21 d
Adult female 2-60 d
Range of mating 1-21 d
Gestation period 3-5 d
Egg Sac 1-3000 d
Cyst 1-3000 d
Soybean growth Minimum germinate temperature 13 ° C
Soybean germinate date 115 days (about April 25)
Soybean harvest date 240 days (about August 28)
Optimal soybean growth temperature 27° C
SCN Parasitism Minimum soybean age for parasitism 20 days post germinationc
Maximum soybean age for parasitism 100 days post germinationc
Feed rate 5%

Simulation parameters used in producing data on the Soybean Cyst Nematode Simulation SCNSim framework.

Simulation configuration Sampling frequency 4 days
Iterations 10
Simulation duration 5 years
Virus properties Mutation rates (m) 0, 0.1, 0.2, 0.4, 0.6, 0.8
Virulence (V 0) 0.1, 0.5, 1, 1.5, 2, 2.5, 4
Transmissibility (b 0) 0.5
Infection rate (i 0) 0.2, 0.8
Durability (D) 0.5
Viral load (L) 0.5
eISSN:
2640-396X
Lingua:
Inglese
Frequenza di pubblicazione:
Volume Open
Argomenti della rivista:
Life Sciences, other
Feed RSS della rivista