21 4) Transformed Stochastic Model Let N(t) = current population size D(t) = cumulative deaths Clearly D(t)=C(t)-N(t) Compartmental Structure: Assumptions: Given N(t)=n, D(t)=d Prob{unit increase in N in Δt}=λnΔt Prob{unit shift from in N to D in Δt}=μn(n+d)Δt Two forces of mortality: crowding from live aphids (logistic type) = μn 2 cumulative effect of dead aphids = μnd
{}