How maths modelling helps efforts to eradicate banana bunchy top virus
QUT develops new model to track probability of banana plant infection


Date:
August 10, 2020
Source:
Queensland University of Technology
Summary:
Modelling the predicted movements of pervasive sap-sucking tiny
insects before they infest banana crops has the potential to
become a key tactic in the fight against a devastating virus,
according to new research.

Banana bunchy top virus (BBTV) is an aphid-transmitted banana
disease that has been in Australia since 1913. Researchers have
designed a model that tracked the probability of a banana plant
being infected by aphids that carried the disease.



FULL STORY ========================================================================== Modelling the predicted movements of pervasive sap-sucking tiny insects
before they infest banana crops has the potential to become a key tactic
in the fight against a devastating virus, according to QUT research.


========================================================================== Banana bunchy top virus (BBTV) is an aphid-transmitted banana disease that
has been in Australia since 1913 and has been contained by biosecurity
agencies to southeast Queensland and northern New South Wales.

Badly affected plants will not produce fruit if left unchecked and entire plantations can become infested.

BBTV cannot be cured and infected plants must be destroyed.

QUT researchers have designed a model that tracked the probability of
a banana plant being infected by aphids that carried the disease, with
the findings published in PLOS Computational Biology.

Keypoints:-
* Aphids can fly long distances to new plantations and quickly infect
nearby plants.

* Current inspection measures by biosecurity agents are costly
and time-
consuming.

* Mathematical and statistical models can help to predict areas of
risk of
infection.

* A stochastic mathematical model describes disease spread,
infectivity and
recovery rates.

* External environmental and seasonal factors influence virus spread.

* The framework can be adapted to study dynamics of other vector-borne
diseases.

A 2012 study estimated the benefits from eliminating the disease would
be worth between $16-27 million to Australia each year.



========================================================================== Distinguished Professor Kerrie Mengersen said despite ongoing traditional methods of monitoring and management of the disease, eradication had
proved elusive.

The latest study, conducted in collaboration with biosecurity agents,
focused on a BBTV-infected banana plantation in northern New South Wales.

The location of every diseased plant in the plantation was recorded
using GPS.

Associate Professor Chris Drovandi said the research expanded existing
disease management strategies by calibrating the model to real field data.

"The new model we've developed quantifies the effects of seasonal changes,
the plantation's configuration and spread of banana bunchy top virus
while predicting high-risk areas," Associate Professor Drovandi said.



========================================================================== "Peak transmission occurs when temperatures reach 25-30 degrees, so
weather is an important factor to consider in the complex dynamics
of BBTV spread." Since 2014, the banana farm has undergone monthly
inspections implementing a "rogue-and-remove" disease management strategy.

QUT researcher Abhishek Varghese joined the study as part of an
undergraduate vacation research scholarship, visiting the farm and
meeting industry officials.

He said it was difficult to see the symptoms of virus on plants from the
air, or by using drones, as the leaves needed to be viewed underneath
for infestations.

"The banana trees grow along a steep slope and insects can be swept up and pushed to different parts of the plantation by seasonal forces," he said.

"Since the 1930s field surveyors have scoured the plantation attempting
to individually identify infections by checking banana leaves showing
a choked or bunched appearance.

"They mark the infected area without interrupting the insects and spray paraffin oil to ensure the aphids can't escape and inject a systemic insecticide and herbicide (glyphosate) slowly killing the banana plant
and all the aphids inside it." Mr Varghese, who is studying a dual
engineering and economics degree at QUT, said stochastic mathematical
modelling also helped pinpoint areas where the disease remained latent
in the soil two or three months after trees had been removed.

"This is an expensive and laborious process for field surveyors so a
precise forecasting tool may assist in pinpointing areas to inspect more carefully, reducing costs and making the job easier," he said.

BBTV was first introduced to Australia in 1913 via infected suckers from
Fiji and spread locally through the banana aphid, Pentalonia nigronervosa.

"This is a fantastic example of talented students using mathematical
and statistical skills to help solve real problems facing farmers and
the agriculture industry," Professor Mengersen said.


========================================================================== Story Source: Materials provided by
Queensland_University_of_Technology. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Abhishek Varghese, Christopher Drovandi, Antonietta Mira, Kerrie
Mengersen. Estimating a novel stochastic model for within-field
disease dynamics of banana bunchy top virus via approximate
Bayesian computation.

PLOS Computational Biology, 2020; 16 (5): e1007878 DOI: 10.1371/
journal.pcbi.1007878 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200810103241.htm

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