These experiments were designed to study the effects on take-all of different populations of cereal volunteers in set-aside/conservation covers sown with mustard, and to investigate whether there is, perhaps, a threshold population below which effects on take-all in the following crop(s) are so small that they can be ignored.
The Allee effect means that there is a threshold population level below which the population goes to extinction.
Such a phenomenon of the existence of a threshold population level, below which the population goes to extinction, is called an Allee effect [ 12, 16].
Gomulkiewicz and Holt (1995) did not consider density-dependent effects but assumed that extinction risk was elevated below a threshold, critical population size (Nc).
At lower group sizes, at or just below the threshold population density for disease persistence, the parameters of infection itself, such as disease-induced mortality and the rates of transfer between different infectious states, became more important in influencing prevalence.
The simulations indicate that to preclude resistance, antiviral drugs must be strong enough and act fast enough to drive the viral population below a threshold level.
Strategies which suppress insect populations below a threshold level could potentially reduce the damage caused by transmitted plant viruses [8].
It is predicted that a threshold host population size exists, below which parasites will not be able to persist.
Such models make explicit assumptions about initial population size, threshold population size (below which the population is at high extinction risk) population growth, and fitness changes across time as a result of the initial change in environment, mutation rates, and subsequent selection.
As long as we suppress the population and make it smaller, below a threshold, it will have a big impact on the disease burden".
