Heteroclinic Connection in a Nicholson's delayed model with Harvesting term

In this paper we prove the existence of monotone heteroclinic solutions for the delayed Nicholson's blowflies model with harvesting: $$x'(t) = -\delta x(t) - Hx(t-\sigma) + \rho x(t-r)e^{-x(t-r)}.$$ Under the condition $1 < \dfrac{\rho}{\delta+H} \leq e$, we establish the connection between the equilibria $0$ and $\ln(\rho/(\delta+H))$ using the Wu and Zou monotone iteration method adapted for two delays ($\sigma \neq r$). The proof combines explicit upper and lower solutions construction with characteristic equation analysis, supported by numerical simulations.