Project Title:

Human behaviour, the flow of information and crop disease management 

Project Summary:

While the spread of plant disease depends strongly on biological factors controlling transmission, epidemics clearly also have a human dimension. Disease control depends on decisions made by individual growers, which are in turn influenced by a broad range of factors. However, control of many diseases requires co-ordinated management between growers, who must all co-operate to be successful. Despite this, human behaviour has rarely been included in plant epidemic models. 

Considering Cassava Brown Streak Disease (CBSD; a viral disease of cassava) as a case study, we model how access to information, the risk aversion of growers, and the perceived benefit of disease control influence participation in disease management. CBSD can be transmitted within season by a whitefly vector, and between seasons via vertical transmission. The former means that the outcome of one grower depends on the actions of others as whitefly vectors can travel between fields and spread infection, providing an ideal case study for co-ordinated control schemes. 

In sub-Saharan Africa, clean seed systems (CSS) have been proposed as a means of limiting the vertical transmission of CBSD. Though broadly beneficial, CSS are susceptible to freeloaders who benefit from control measures without incurring any costs. This threatens the long-term success of such schemes. We study the system in both a spatial and non-spatial setting, with the behavioural component included as both a game-theoretic assessment of payoffs for each control strategy as well as the spread of information between growers. Importantly, we investigate which factors ensure sustained participation in CSS, since oscillations in participation may lead to periodic disease incursions.