The Nicholson-Bailey Model
by Mike Martin

This page generates plots for the Nicholson-Bailey Model:

The model helps to descibe the dynamics between the population levels of two different insect species; one of the species, the host, can be paralyzed and used to host the eggs of the other insect species, the parasitoid.   Nt is the density of the host species in generation t and Pt is the density of the parasitoid species in generation t.   The fraction of hosts not parasitized is e-aP where a is the searching efficiency (or the probability that a given parasitoid will encounter a host over the course of their lifetime) and P represents Pt.   r is the number of eggs laid by a host that survive through the larvaae, pupae, and adult stages.   Similarly, g represents the number of eggs laid by a parasitoid on a single host that survive through larvae, pupae, and adult stages.   T is the last generation considered with the simulation.   N1 is the initial host density and P1 is the initial parasitoid density.   The sequence Nt is displayed in the graph in BLUE and the sequence Pt is given in BROWN.

Enter in the values of the non-negative parameters (descibed above), then press the "Evaluate" button.

a =  

g =  

r =  

T =  

N1 =  

P1 =  


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