Vector feeding period variability in epidemiological models of persistent plant viruses.

GRILLI, M.P., HOLT, J.

ECOLOGICAL MODELLING

Elsevier

Lugar: Amsterdam; Año: 2000 vol. 126 p. 49 - 57

0304-3800

Plant viruses are transmitted from one host plant to another by vectors, frequently phloem feeding insects.Persistent, circulative plant viruses are found in the phloem of the host plant and can be transmitted within a minimum period of minutes or hours by their insect vectors. The probability of virus inoculation increases with the period of exposure of the host to the vector. In mathematical models of plant virus disease epidemics it is frequently assumed that virus transmission is a simple bilinear process, i.e. is proportional to the abundance of hosts, vectors, and a constant ‘contact rate’ parameter. Thus no account is taken of any minimum feeding period required for virus transmission or of how the vector feeding period duration affects the probability of transmission. A theoretical model was developed to evaluate these effects. The results of numerical simulation with two models, conventional and with variable feeding period, were compared. The conventional model was adequate when the mean feeding period by a vector on a plant (T)]the average feeding period required for one inoculation event to occur (a). Particularly in pathosystems where the vectors are relatively inefficient virus transmitters the situation TBa can occur, leading to underestimation or overestimation of the inoculation rate when variability is ignored. Genetic changes in host or vector, e.g. associated with a new host plant variety, which result in an increase in the variability of the vector feeding period could give rise to unexpected changes in disease dynamics.